Low-temperature waste heat power generation method and device based on organic Rankine cycle

Abstract

According to the low-temperature waste heat power generation method and device based on the organic Rankine cycle, a waste heat source temperature signal and a ship posture angle are collected, and heat grade levels are recognized through graded heat capacity analysis to establish heat source graded configuration; identifying a liquid deviation area, adjusting a working medium distribution proportion to form an anti-bias parameter, monitoring a degradation product, collecting a purity deviation amount, and mapping a working medium circulation state; evaporation grading analysis is executed to recognize a pressure demarcation point, available enthalpy drop is extracted, low-temperature evaporation working condition parameters are determined, and a grading evaporation control sequence is constructed; turbine operation parameters are adjusted to obtain exhaust steam flow, and the exhaust steam flow is liquefied, cooled, pressurized and reinjected to form circulating working medium flow, and circulating pressure is detected to generate circulating stable parameters; turbine rotor gravity offset is generated to adjust magnetic suspension electromagnetic force to form an inclination compensation state, thermal efficiency analysis is carried out to identify an efficiency loss area, recoverable waste heat optimization cycle parameters are extracted to generate a power generation control instruction, and waste heat recycling is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of ship energy recovery technology, in particular to a low-temperature waste heat power generation method and device based on organic Rankine cycle. BACKGROUND

[0002] The waste heat discharged by the main and auxiliary machines of a ship during operation includes high-temperature exhaust gas, medium-temperature cooling water, and low-temperature lubricating oil in various forms, and has significant energy recovery value. The organic Rankine cycle technology has become the main technical solution for ship waste heat power generation due to its good adaptability to medium and low temperature heat sources.

[0003] However, the existing ship waste heat recovery system has many technical bottlenecks when operating in low-temperature environments. The physical properties of the working medium change significantly under low-temperature conditions, and the large reduction in condensing temperature causes the system pressure to fluctuate dramatically, while the traditional control strategy uses fixed set values and cannot adapt to the dynamic changes in environmental temperature. Changes in the attitude of the ship during navigation, such as roll and pitch, cause unbalanced distribution of the working medium in the system and equipment vibration, and the existing system lacks targeted dynamic compensation means. The existing technology usually uses a single evaporation condition, which cannot fully utilize each level of heat source, and lacks an online monitoring mechanism for working medium performance degradation and a self-adaptive adjustment mechanism for cycle parameters. In addition, the eccentricity of the turbine rotor caused by the inclination of the ship body increases bearing loss and leakage loss, while traditional mechanical bearings cannot provide dynamic compensation, and magnetic suspension bearings can provide controllable support force, but lack an active adjustment strategy based on attitude changes. SUMMARY

[0004] The present application discloses a low-temperature waste heat power generation method and device based on organic Rankine cycle, which realizes the adaptive utilization of different grade waste heat under low-temperature environments by establishing a temperature compensation mechanism and a heat source grading configuration system; responds to system disturbances caused by changes in the attitude of the ship body by constructing anti-deviation flow parameters and working medium performance monitoring mechanisms; adapts to dynamically changing heat source conditions by establishing a graded evaporation control and sliding pressure operation strategy; ensures stable operation of the turbine and optimizes cycle performance by implementing magnetic suspension inclination compensation and efficiency loss identification technology, and finally forms a complete adaptive waste heat recovery power generation control scheme.

[0005] The first aspect of the present application proposes a low-temperature waste heat power generation method based on organic Rankine cycle, comprising the following steps: Collecting temperature signals of the waste heat sources of the main and auxiliary machines of a ship and the attitude angle of the ship body, identifying the heat grade by graded heat capacity analysis of the temperature signals, and establishing a heat source grading configuration through the heat grade; identify a liquid deviation region based on the heat source hierarchical configuration and the ship body attitude angle, adjust a work medium distribution ratio of each section based on the liquid deviation region to form an anti-deviation flow parameter, perform work medium performance monitoring and locate degradation products according to the anti-deviation flow parameter, and collect purity deviation amounts of the degradation products to map a work medium circulation state; perform evaporation hierarchical analysis and identification of a pressure demarcation point for the work medium circulation state, extract an available enthalpy drop of the pressure demarcation point, determine a low-temperature evaporation working condition parameter through the available enthalpy drop and the heat grade, and construct a hierarchical evaporation control sequence according to the low-temperature evaporation working condition parameter; adjust turbine operating parameters to obtain turbine exhaust steam flow according to the hierarchical evaporation control sequence, perform liquefaction cooling on the turbine exhaust steam flow to obtain a condensed work medium flow, perform pressure boosting and reinjection on the condensed work medium flow to form a circulation work medium flow, detect circulation pressure based on the circulation work medium flow to generate a circulation stability parameter; generate a turbine rotor gravity deviation amount according to the circulation stability parameter and the ship body attitude angle, adjust magnetic suspension axial electromagnetic force to form a tilt compensation state using the gravity deviation amount, perform thermal efficiency analysis on the circulation work medium flow to identify an efficiency loss region based on the tilt compensation state, extract recoverable waste heat in the efficiency loss region to optimize a circulation parameter, and generate a power generation control instruction.

[0006] The second aspect of the present application proposes a low-temperature waste heat power generation device based on an organic Rankine cycle, comprising: a signal acquisition module configured to acquire a temperature signal of a ship main engine waste heat source and a ship body attitude angle, perform hierarchical heat capacity analysis on the temperature signal to identify a heat grade, and establish a heat source hierarchical configuration through the heat grade; an anti-deviation flow control module configured to identify a liquid deviation region based on the heat source hierarchical configuration and the ship body attitude angle, adjust a work medium distribution ratio of each section based on the liquid deviation region to form an anti-deviation flow parameter, perform work medium performance monitoring and locate degradation products according to the anti-deviation flow parameter, and collect purity deviation amounts of the degradation products to map a work medium circulation state; an evaporation optimization module configured to perform evaporation hierarchical analysis and identification of a pressure demarcation point for the work medium circulation state, extract an available enthalpy drop of the pressure demarcation point, determine a low-temperature evaporation working condition parameter through the available enthalpy drop and the heat grade, and construct a hierarchical evaporation control sequence according to the low-temperature evaporation working condition parameter; a circulation driving module configured to adjust turbine operating parameters to obtain turbine exhaust steam flow according to the hierarchical evaporation control sequence, perform liquefaction cooling on the turbine exhaust steam flow to obtain a condensed work medium flow, perform pressure boosting and reinjection on the condensed work medium flow to form a circulation work medium flow, detect circulation pressure based on the circulation work medium flow to generate a circulation stability parameter; The tilt compensation module is used for generating a turbine rotor gravity offset according to the circulation stability parameter in combination with the ship body attitude angle, adjusting the magnetic suspension axial electromagnetic force to form a tilt compensation state, performing heat efficiency analysis on the circulation working medium flow based on the tilt compensation state to identify an efficiency loss area, and extracting recoverable waste heat in the efficiency loss area to optimize the circulation parameter and generate power generation control instructions.

[0007] The beneficial effects of the present application are embodied in the following points: first, by performing hierarchical heat capacity analysis and heat grade classification on the waste heat source, different heat exchange equipment and recovery strategies are configured for heat sources of different temperature grades, and cascade utilization of waste heat is realized. By performing evaporation hierarchical analysis, the evaporation process is divided into a preheating section, a boiling section and a superheating section, and differential control is set, combined with sliding pressure operation adaptability analysis to extract a pressure sliding range, so that the system can automatically adjust the operating parameters according to the fluctuations of the heat source and the changes in the condensation conditions under low temperature environment, and the energy conversion efficiency is maintained. Second, the anti-deviation flow parameters are established based on the liquid deviation area identification, and the resonance risk assessment and damping adjustment are performed through liquid surface oscillation frequency analysis, so that the imbalance of working medium distribution and system oscillation caused by ship body rolling are suppressed. By analyzing the gravity offset, the rotor eccentricity compensation strategy is established, the main shaft and the auxiliary shaft are determined, and the layered current distribution is performed, so that the magnetic suspension system can adjust the axial electromagnetic force in real time to compensate the rotor eccentricity caused by the ship body tilt, reduce the bearing loss and leakage loss, and improve the operating stability of the turbine under dynamic working conditions of the ship. Finally, by positioning the degradation products and using molecular vibration spectrum feature extraction and online spectrum comparison to identify the degradation type, the working medium circulation state is mapped combined with the purity deviation, and the real-time evaluation of the working medium aging degree is realized. By tracking the enthalpy change of the circulation working medium flow to generate energy conversion characteristics and performing segmented evaluation, an efficiency distribution map is formed, and the efficiency loss areas of the turbine, the evaporator, the condenser and the circulating pump are identified. Recoverable waste heat is extracted in the loss area, and the circulation parameters are optimized to form a complete optimization loop from state monitoring to parameter adjustment, and the performance of the system is continuously improved.

[0008] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present application. BRIEF DESCRIPTION OF DRAWINGS

[0009] The drawings herein show specific examples of the technical solutions described in the present application, and constitute part of the specification together with the specific embodiments, for explaining the technical solutions, principles and effects of the present application.

[0010] Unless specifically stated, the same reference signs in different drawings represent the same or similar technical features, and different reference signs may also be used to represent the same or similar technical features.

[0011] Figure 1is a flow chart of a low-temperature waste heat power generation method based on an organic Rankine cycle according to the present application.

[0012] Figure 2 is a structural block diagram of a low-temperature waste heat power generation device based on an organic Rankine cycle according to the present application. DETAILED DESCRIPTION

[0013] In the following description, for purposes of explanation and not limitation, specific details are set forth such as particular architectures, techniques, etc. in order to provide a thorough understanding of the embodiments of the present application. However, it will be apparent to those skilled in the art that the present application can be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known methods, devices, circuits, and

[0014] It is to be understood that the terminology "including", "comprising", "consisting" and "consisting essentially of" used in the specification and the appended claims, indicates the presence of the stated features, integers, steps, operations, elements, and / or components but does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0015] Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the application. Thus, the appearances of the phrases "in one embodiment" or "in an embodiment" or "in other embodiments" or "in still other embodiments" in various places throughout this specification are not necessarily referring to the same embodiment, unless otherwise specified. The terms "including", "comprising", "consisting essentially of" and "consisting of" are used interchangeably, unless otherwise specified.

[0016] The technical solutions of the embodiments of the present application are introduced as follows.

[0017] As shown in Figure 1 The embodiments of the present application provide a low-temperature waste heat power generation method based on an organic Rankine cycle, including the following steps S110-S150: Step S110, collecting temperature signals of a ship main engine waste heat source and a ship body attitude angle, performing hierarchical thermal capacity analysis on the temperature signals to identify a thermal grade level, and establishing a hierarchical configuration of the heat source through the thermal grade level.

[0018] Specifically, the temperature signals of the main and auxiliary engine waste heat sources and the ship body attitude angle are collected. A network of temperature sensors is deployed at key exhaust discharge positions of the main and auxiliary engines to monitor the temperature data of each waste heat source in real time. Thermocouple temperature sensors are installed at the outlet of the main engine exhaust pipe, the cylinder sleeve cooling water circulation loop, the oil cooling system outlet, and the rear end of the supercharger to measure the temperature in the range of 50-600°C with a measurement accuracy of within ±1°C. Temperature collection points are set at the exhaust pipe, cooling water loop, and lubricating oil system outlet of the auxiliary diesel generator set to collect the waste heat temperature signals during the operation of the auxiliary engine. The temperature values and time stamp information of each measurement point are recorded by a distributed data collection system at a sampling frequency of once per second. Attitude sensors are deployed at key positions on the ship body to monitor attitude parameters such as the roll angle, pitch angle, and yaw angle of the ship. The attitude sensors use a combination of three-axis gyroscopes and accelerometers for measurement, with an angle measurement accuracy of 0.1 degrees and a sampling frequency of 10 times per second. The temperature variation characteristics of the main engine under different load conditions are collected, including typical operating states such as idle speed, economic speed, and full load. The temperature fluctuation data during the start-stop process of the auxiliary engine and the temperature stable data during the stable operation stage are recorded. During actual ship navigation, the main engine exhaust temperature usually fluctuates in the range of 300-450°C, the cylinder sleeve water temperature is maintained in the range of 70-90°C, and the oil temperature is maintained at the level of 60-80°C.

[0019] The temperature signals are analyzed by hierarchical heat capacity analysis to identify the heat grade. The collected waste heat source temperature signals are preliminarily classified according to the temperature value range. Through statistical analysis of the temperature data, the temperature distribution characteristics and fluctuation rules of each waste heat source are identified. The numerical distribution of the main engine exhaust temperature is analyzed, and the exhaust waste heat with a temperature higher than 400°C is marked as a high-temperature heat source candidate. The temperature distribution of the cylinder sleeve cooling water and oil cooling system is analyzed, and the waste heat with a temperature in the range of 60-100°C is marked as a medium-temperature heat source candidate. The waste heat with a temperature lower than 60°C from other auxiliary systems is identified as a low-temperature heat source candidate. Hierarchical heat capacity analysis is performed, the mass flow is determined according to the engine design parameters and operating conditions, and the heat capacity characteristics of each heat source are calculated based on the temperature values. The mass flow of the main engine exhaust waste heat is large and the temperature is high, so the heat capacity value is significantly higher than that of other waste heat sources. Although the cylinder sleeve water and oil system have a medium temperature, the circulation flow is stable, and the heat capacity value is at a medium level. According to the heat capacity analysis results and temperature distribution characteristics, the heat grade of each waste heat source is identified. The waste heat source with a heat capacity value greater than twice the average value and a temperature higher than 400°C is determined as the first heat grade, which has the highest energy recovery value. The waste heat source with a heat capacity value between the average value and twice the average value and a temperature in the range of 60-400°C is determined as the second heat grade, which is suitable for medium-temperature utilization. The waste heat source with a heat capacity value less than the average value and a temperature lower than 60°C is determined as the third heat grade, which has relatively limited recovery value.

[0020] A graded configuration of heat sources is established based on heat grade. For high-temperature waste heat sources of grade 1, high-efficiency heat exchange devices and priority recovery channels are configured. The exhaust heat from the main engine is configured as the primary energy source of the heat source system, with an independent high-temperature heat exchange loop. For medium-temperature waste heat sources of grade 2, standard heat exchange equipment and conventional recovery channels are configured. Waste heat from cylinder liner water and lubricating oil systems is configured as an auxiliary energy source of the heat source system, with series or parallel medium-temperature heat exchange loops. For low-temperature waste heat sources of grade 3, simple heat exchange devices and supplementary recovery channels are configured. Low-temperature waste heat is configured as a backup energy source for the system, activated when the primary heat source is insufficient. The corresponding heat exchanger type and heat exchange area are determined based on the temperature range and heat capacity characteristics of each heat grade. Grade 1 heat sources are configured with high-temperature resistant plate-fin heat exchangers with a larger heat exchange area to fully recover heat. Grade 2 heat sources are configured with plate or shell-and-tube heat exchangers, with the heat exchange area set according to actual heat capacity requirements. Grade 3 heat sources are configured with simple tubular heat exchangers with a relatively smaller heat exchange area. Establish a graded configuration scheme for heat sources, including information such as the grade of each heat source, configured equipment, recovery channels, and activation priority.

[0021] Step S120: Identify liquid deviation areas based on heat source classification configuration and ship attitude angle; adjust the working fluid distribution ratio of each section based on the liquid deviation areas to form anti-deviation parameters; perform working fluid performance monitoring and locate degradation products according to the anti-deviation parameters; and collect purity deviation data of degradation products to map working fluid circulation status.

[0022] Specifically, liquid displacement regions are identified based on the hierarchical configuration of heat sources and the ship's attitude angle. The high-temperature heat exchanger in the primary heat source configuration has a larger working fluid flow rate and higher temperature. The motion characteristics of the liquid working fluid under the combined effects of gravity and inertia differ from those in the medium- and low-temperature systems. The lateral displacement trend of the liquid working fluid is determined by the ship's roll angle; when the roll angle exceeds 5 degrees, the liquid begins to exhibit significant lateral displacement. The longitudinal displacement trend of the liquid working fluid is determined by the pitch angle; when the pitch angle exceeds 3 degrees, the liquid exhibits longitudinal flow displacement in the pipeline. The influence of the bow angle on the liquid distribution within the pipeline system is analyzed; the centrifugal force caused by the bow motion leads to liquid displacement and accumulation at bends. Combining the spatial location of the heat exchangers and the pipeline routing, the direction and magnitude of liquid displacement within each heat source system are determined. During actual ship navigation, when the ship experiences significant roll, the liquid working fluid in one side of the heat exchanger will concentrate on the other side, resulting in a localized increase in liquid level and a decrease in liquid level on the other side, creating an uneven liquid distribution. Spatial mapping analysis was performed between attitude angle values ​​and heat exchanger position coordinates to identify key and minor areas of liquid displacement. Severe displacement areas with roll angles greater than 8 degrees or pitch angles greater than 5 degrees were marked. The identified liquid displacement areas were categorized and recorded according to displacement direction, displacement magnitude, and the corresponding heat source level, forming liquid displacement area distribution data.

[0023] In some embodiments, the step of adjusting the working fluid distribution ratio of each segment based on the liquid offset region to form anti-flow deviation parameters includes: analyzing the liquid surface oscillation frequency based on the liquid offset region to identify the resonance risk frequency band; designing damping adjustment for the resonance risk frequency band to generate a flow compensation distribution scheme; constructing dynamic compensation rules based on the flow compensation distribution scheme and the liquid offset region; and establishing anti-flow deviation parameters based on the dynamic compensation rules.

[0024] Based on liquid displacement regions, frequency analysis of surface oscillations was conducted to identify resonance risk frequency bands. For each identified liquid displacement region, the displacement amplitude and spatial distribution characteristics were extracted. Based on the spatial spacing and amplitude distribution of the liquid displacement regions, the wavelength characteristics of the surface oscillations were calculated; the distance between the displacement regions reflects the spatial scale of the oscillation wavelength. Combining the period of change in the ship's attitude angle, the corresponding oscillation frequency was calculated: 0.125Hz for a roll period of 8 seconds and 0.167Hz for a pitch period of 6 seconds. Based on the liquid depth h and gravitational acceleration g within the heat exchanger, the natural oscillation frequency of the working fluid was calculated as f = √(g / h) / (2π). The frequency difference between the ship's motion frequency and the natural oscillation frequency of the working fluid was calculated. When the frequency difference is small, resonance is easily generated between the ship's motion and the surface oscillation, leading to a sharp increase in oscillation amplitude. Analysis of the characteristic differences of liquid displacement regions in different heat source systems revealed that the high-temperature working fluid density in the first-level heat source system is lower, resulting in a relatively higher natural oscillation frequency, while the natural oscillation frequency of the medium-temperature working fluid in the second-level heat source system is at a moderate level. By analyzing the correlation between frequency difference and offset amplitude, frequency ranges with resonance risk are identified, forming resonance risk frequency bands.

[0025] A damping adjustment flow compensation allocation scheme is designed for the resonance risk frequency band. For the identified resonance risk frequency band, corresponding damping adjustment strategies are designed to suppress resonance. The damping characteristics of the liquid system are altered by adjusting the distribution rhythm of the working fluid flow. The damping coefficient of the flow adjustment is increased when approaching the resonance frequency band to reduce the system's response amplitude to external stimuli. The adjustment amplitude and frequency of flow compensation are set, with the adjustment amplitude determined according to the resonance risk level. The flow compensation amplitude is set to 20%-40% of the baseline flow for high-risk frequency bands and 10%-20% for medium-risk frequency bands. An artificial damping effect is created through rapid fine-tuning of the flow; the frequency of rapid fine-tuning should avoid the resonance frequency band and be higher than the ship's motion frequency. A flow compensation allocation scheme is established, quantifying the compensation flow, timing, and duration for each pipe section. Differentiated compensation strategies are set for different deviation areas; the compensation intensity is increased in areas with severe deviation, while standard compensation is used in areas with slight deviation. The impact of flow compensation on the heat exchange efficiency of each heat source system is analyzed to ensure that compensation adjustment does not significantly reduce heat exchange performance.

[0026] Dynamic compensation rules are constructed based on the flow compensation allocation scheme and liquid offset region. A correspondence between offset amplitude and compensation intensity is established; the larger the offset amplitude, the higher the corresponding compensation intensity. A compensation trigger threshold is set; when the liquid offset amplitude exceeds the set threshold, the compensation mechanism is automatically activated. Different compensation rules are set for different offset directions: lateral offset is mainly compensated through the flow difference between the left and right pipes, while longitudinal offset is compensated through flow adjustment of the upstream and downstream pipe sections. A dynamic adjustment mechanism for the compensation rules is established, dynamically correcting the compensation parameters based on real-time monitoring of the offset status and the trend of hull attitude changes. When the rate of change of the hull attitude angle is large, the compensation intensity is increased in advance for preventative adjustment. When the attitude tends to stabilize, the compensation intensity is gradually reduced to restore normal operation. A priority sequence of compensation rules is set, with compensation rules for high-risk resonance frequency bands having the highest priority, followed by conventional offset compensation rules.

[0027] Anti-flow deviation parameters are established based on dynamic compensation rules. The system's anti-flow deviation parameter configuration is generated by setting various parameters according to the dynamic compensation rules. The correspondence between offset amplitude and compensation intensity is transformed into the core values ​​of the anti-flow deviation parameters; the larger the offset amplitude, the stronger the corresponding anti-flow deviation parameter. The compensation trigger threshold is transformed into the activation condition of the anti-flow deviation parameters; different thresholds correspond to different levels of anti-flow deviation response. According to the compensation rules for different offset directions, a directional adaptation mechanism for the anti-flow deviation parameters is set: lateral offset parameters control the flow difference between the left and right pipes, and longitudinal offset parameters control the flow adjustment between the upstream and downstream pipe sections. The dynamic adjustment mechanism is transformed into the adaptive characteristics of the anti-flow deviation parameters, with parameters dynamically corrected based on real-time offset status and ship attitude change trends. The preventative adjustment strategy is transformed into the predictive function of the anti-flow deviation parameters; when the ship attitude angle change rate is large, the anti-flow deviation parameters are automatically enhanced in advance. The recovery mechanism is transformed into the regression logic of the anti-flow deviation parameters; when the attitude tends to stabilize, the parameters gradually decrease to return to normal mode. Based on the priority sequence of the compensation rules, a hierarchical system for the anti-flow deviation parameters is established: high-risk resonance corresponds to level one anti-flow deviation parameters, and normal offset corresponds to level two anti-flow deviation parameters; different levels of parameters have different response priorities. The anti-deviation parameters at each level are converted into specific working fluid flow rate setpoints. The first-level anti-deviation parameters correspond to the emergency adjustment flow rate range for each pipe section, while the second-level parameters correspond to the standard adjustment flow rate range. An anti-deviation parameter configuration database is established to record the flow rate setpoints, temperature reference values, and pressure reference values ​​for each pipe section under different deviation states, serving as the benchmark for subsequent performance monitoring and anomaly judgment.

[0028] Based on the anti-deviation flow parameters, the performance of the working fluid is monitored to locate degradation products. The working fluid circulation system is monitored according to the parameters in the anti-deviation flow parameter configuration database. During the working fluid distribution adjustment process, the temperature, pressure, and flow rate changes of the working fluid in each pipe section are monitored. Abnormal fluctuations in working fluid temperature identify potential locations of degradation reactions; areas of sudden temperature increases or decreases may indicate changes in the working fluid's chemical properties. Abnormal changes in working fluid pressure identify leaks or blockages within the system; abnormal pressure drops typically correspond to leaks, while abnormal pressure increases correspond to blockages. The degree of deviation in working fluid flow rate is analyzed; locations with significant differences between the actual flow rate and the anti-deviation flow parameter settings are marked as abnormal monitoring points. Working fluid samples are collected at abnormal monitoring points for component analysis to identify the types and contents of degradation products in the working fluid. Changes in the chemical composition of the working fluid samples are detected using gas chromatography or liquid chromatography. The main types of working fluid degradation products are identified, including different categories such as oxidative degradation products, thermal decomposition products, and polymerization reaction products.

[0029] In some embodiments, the step of collecting purity deviation data of the degradation products to map the working fluid circulation status includes: extracting molecular vibrational spectral features from the degradation products; identifying the degradation type based on online spectral comparison of the molecular vibrational spectral features; performing concentration quantification on the degradation type to generate a purity deviation; and mapping the working fluid circulation status based on the purity deviation.

[0030] Molecular vibrational spectral features are extracted from degradation products. Samples of the working fluid containing degradation products are collected at the identified locations where they are generated for spectral analysis. Infrared or Raman spectroscopy is used to analyze the molecular vibrations of the collected working fluid samples. The working fluid sample is placed in the spectrometer's measurement window, and molecular vibrational signals are acquired by irradiating the sample with infrared light or laser. The spectral absorption or scattering intensity of the sample is recorded within different wavenumber ranges to form a complete spectral curve. Characteristic absorption and scattering peaks in the spectral curve are identified; these peaks correspond to specific chemical bond vibrations in the working fluid and degradation product molecules. Key parameters such as the position, intensity, and peak width of the characteristic peaks are extracted to form molecular vibrational spectral feature data. Newly appearing absorption peaks in the spectral curve are analyzed; these new peaks typically correspond to new chemical bonds formed during the degradation reaction. The differences between the sample spectrum and the standard spectrum of fresh working fluid are compared to identify significant regions of spectral change. In marine organic Rankine cycles, carbonyl characteristic peaks appear in the spectrum during oxidative degradation of the working fluid, and characteristic peaks of unsaturated hydrocarbons are produced during thermal decomposition. The appearance and intensity changes of these new peaks directly reflect the degree of degradation.

[0031] Degradation types are identified through online spectral comparison based on molecular vibrational spectral characteristics. The extracted molecular vibrational spectral feature data is compared and matched with a standard degradation product spectral database. This database contains spectral feature information for various typical degradation products, including oxidation products, thermal decomposition products, and polymerization products. Possible degradation product types are initially screened based on the matching degree of spectral characteristic peak positions. The similarity between the sample spectrum and the standard spectrum is calculated, quantified using spectral correlation coefficients or spectral matching degrees. The degradation type corresponding to the standard spectrum with the highest similarity is selected as the primary identification result. When multiple standard spectra with close similarity exist, a comprehensive judgment is made by combining peak intensity ratios and peak width characteristics. The primary and secondary categories of degradation products are identified; the primary category corresponds to the degradation type with the highest spectral matching degree, and the secondary category corresponds to the type with the second highest matching degree.

[0032] The purity deviation is calculated by performing concentration quantification on the degradation type. Based on the identified degradation type, the corresponding concentration quantification method is selected. Concentration is calculated using the intensity values ​​of spectral characteristic peaks; peak intensity and degradation product concentration typically show a linear or logarithmic relationship. A quantitative relationship curve between degradation product concentration and peak intensity is established, obtained through concentration gradient experiments on standard samples. The corresponding concentration value is found on the quantitative relationship curve based on the characteristic peak intensity values ​​of the sample spectrum. The total concentration of all degradation products is calculated to obtain the total concentration of degradation products in the working fluid sample. The actual purity of the working fluid is calculated by relating the total concentration of degradation products to the purity of the working fluid. The working fluid purity equals 100% minus the percentage of degradation product concentration. The actual purity is compared with the standard purity of the fresh working fluid to calculate the purity deviation. The purity deviation calculation formula is established: P_deviation = (P_standard - P_actual) / P_standard × 100%, where P_standard is the standard purity and P_actual is the actual purity. The magnitude of the purity deviation at each monitoring point is analyzed to identify locations with severe purity deviation and locations with good purity.

[0033] The purity deviation is used to map the working fluid circulation status. The spatial distribution characteristics of the purity deviation are analyzed to identify the distribution patterns of high- and low-value deviation regions. The location distribution of high-value regions determines the main areas of working fluid degradation and degradation diffusion paths. The numerical statistical characteristics of the purity deviation are analyzed to calculate the average deviation, maximum deviation, and standard deviation of the entire system. Based on the magnitude of the average deviation, the overall aging degree and remaining performance level of the working fluid are determined. An average deviation of less than 5% is mapped to an excellent working fluid circulation state, 5%-10% to a normal state, 10%-20% to a state of concern, and greater than 20% to a state of alert. The temporal trend of the purity deviation is analyzed, and the rate of performance degradation of the working fluid is predicted by the rate of deviation growth over time. A rapid rate of deviation growth indicates accelerated working fluid degradation, requiring timely maintenance measures. The working fluid circulation status is systematically represented according to status level, main problems, and recommended measures, providing a basis for decision-making regarding system maintenance and working fluid replacement.

[0034] Step S130: Perform evaporation classification analysis to identify pressure boundary points for the working fluid circulation state, extract the available enthalpy drop of the pressure boundary points, determine the low-temperature evaporation operating parameters through the available enthalpy drop and heat grade, and construct a graded evaporation control sequence based on the low-temperature evaporation operating parameters.

[0035] Specifically, pressure thresholds are identified through evaporation classification analysis based on the working fluid circulation state. The evaporator's operating strategy is determined according to the working fluid circulation state level: standard evaporation conditions are used under excellent conditions, optimized evaporation conditions under normal conditions, protective evaporation conditions under caution conditions, and restricted evaporation conditions under warning conditions. The phase change process characteristics of the working fluid within the evaporator are analyzed, and key nodes in the liquid-to-gas transition are identified using temperature and pressure monitoring data. The liquid phase temperature and pressure of the working fluid at the evaporator inlet are monitored, and temperature and pressure change curves during the evaporation process are recorded. The initial pressure point at which the working fluid begins to boil and the termination pressure point for complete evaporation are identified; the area between these two pressure points is defined as the evaporation pressure range. In a marine organic Rankine cycle system, when the main engine exhaust heats the R245fa working fluid as a heat source, the working fluid enters the evaporator in a liquid state. As the heat absorption temperature and pressure gradually rise, the working fluid begins to boil and generate bubbles when the pressure reaches saturation. Subsequently, the gas and liquid phases coexist and continue to evaporate, eventually becoming completely gaseous and continuing to absorb heat to become superheated steam. The pressure gradient distribution within the evaporation pressure range is analyzed to identify regions of drastic pressure changes and relatively stable pressure areas. The boundary locations of evaporation stages are identified by abrupt changes in the pressure gradient, dividing the evaporation process into three stages: preheating, boiling, and superheating. The pressure boundary points for each evaporation stage are determined: the boundary between the preheating and boiling stages corresponds to the pressure at which the working fluid reaches its saturation temperature, and the boundary between the boiling and superheating stages corresponds to the pressure at which the working fluid is completely vaporized. The specific values ​​of each pressure boundary point and its corresponding temperature information are recorded to form a pressure boundary point dataset.

[0036] Extract the available enthalpy drop at pressure thresholds. Using pressure and temperature data at each pressure threshold, query the corresponding specific enthalpy value from the working fluid thermodynamic property database. Obtain the specific enthalpy values ​​at the start and end of the preheating section; the difference between the two is the available enthalpy drop for the preheating section. Obtain the specific enthalpy values ​​at the start and end of the boiling section; the difference between the two is the available enthalpy drop for the boiling section. Obtain the specific enthalpy values ​​at the start and end of the superheating section; the difference between the two is the available enthalpy drop for the superheating section. Analyze the magnitude and proportion of the available enthalpy drop for each section. The available enthalpy drop in the boiling section typically accounts for 60%-80% of the total enthalpy drop, the preheating section for 15%-25%, and the superheating section for 5%-15%. Adjust the extraction strategy for the available enthalpy drop in each section according to the different levels of the working fluid's circulation state. Under optimal conditions, the enthalpy drop of each section is fully extracted to achieve maximum power output. Under caution conditions, the enthalpy drop of the superheated section is appropriately reduced to decrease thermal stress on the working fluid. Under warning conditions, the enthalpy drop of the boiling section is limited to protect the performance of the working fluid. The heat transfer performance of the evaporator and the phase change efficiency of the working fluid are evaluated by the distribution characteristics of the available enthalpy drop. A larger available enthalpy drop indicates a better heat transfer effect and higher energy utilization efficiency in that section. In actual ship operation, when the main engine load increases from 50% to 100%, the exhaust temperature rises, leading to a larger heat transfer temperature difference. The available enthalpy drop in the boiling section increases accordingly, and the system output power increases accordingly.

[0037] In some embodiments, determining the low-temperature evaporation operating parameters using the available enthalpy drop and the heat grade includes: performing a sliding pressure operation adaptability analysis on the available enthalpy drop to extract the pressure sliding range; performing evaporation temperature tracking processing from the pressure sliding range to generate a dynamic operating trajectory; synchronously matching the dynamic operating trajectory with the heat grade to obtain an adaptive temperature band; and extracting the low-temperature evaporation operating parameters based on the adaptive temperature band.

[0038] For example, the step of performing sliding pressure operation adaptability analysis on the available enthalpy drop to extract the pressure sliding range includes: coupling the available enthalpy drop with a heat source to obtain thermodynamic boundary conditions; performing pressure-temperature co-optimization on the thermodynamic boundary conditions to identify the optimal operating curve; constructing upper and lower pressure limits based on the optimal operating curve; and using the upper and lower pressure limits to evaluate the sliding pressure tolerance and generate the pressure sliding range.

[0039] Thermodynamic boundary conditions are obtained by coupling the available enthalpy drop with the heat source and working fluid. The available enthalpy drop data for each evaporation stage are coupled with the corresponding heat source temperature data for analysis. An energy balance relationship is established between the heat source and the working fluid, where the heat released by the heat source equals the heat absorbed by the working fluid plus heat loss. The heat transfer temperature difference and heat transfer coefficient of the preheating process are obtained using the available enthalpy drop and heat source temperature in the preheating stage. The heat transfer characteristics and heat exchange efficiency of the boiling process are obtained using the available enthalpy drop and heat source temperature in the boiling stage. The temperature matching degree and thermal efficiency of the superheating process are obtained using the available enthalpy drop and heat source temperature in the superheating stage. The constraints of the heat source-working fluid coupling are analyzed, including minimum heat transfer temperature difference constraints, maximum heat transfer area constraints, and flow pressure drop constraints. A minimum heat transfer temperature difference boundary is set; an excessively small heat transfer temperature difference will lead to an excessively large heat transfer area and increased equipment investment. In marine organic Rankine cycle systems, the main engine exhaust temperature is typically in the range of 350-450℃, while the working fluid evaporation temperature is generally controlled between 60-90℃. Maintaining a sufficient heat transfer temperature difference between the two ensures the compactness of the heat exchanger while preventing excessively low exhaust temperatures that could lead to acid dew point corrosion. A maximum heat transfer area boundary is set, with the area limited by ship space and equipment layout requirements. A flow pressure drop boundary is also set; excessive pressure drop increases pump power consumption and reduces the system's net output power. Based on these coupled constraints, the effective utilization range of the available enthalpy drop and the corresponding range of working fluid state parameters are determined, forming a mathematical description of the thermodynamic boundary conditions.

[0040] The optimal operating curve is identified through pressure-temperature co-optimization under thermodynamic boundary conditions. The optimization objective is set as maximizing the system's net output power or maximizing the cycle thermal efficiency. Evaporation pressure and evaporation temperature are used as optimization variables, and co-optimization is performed under thermodynamic boundary conditions. System performance index data are obtained through different pressure-temperature combinations. The distribution of performance indexes with pressure and temperature changes is plotted, and the operating point corresponding to the performance peak is identified. The pressure-temperature combination corresponding to the peak position is the optimal operating point. The performance change gradient near the optimal operating point is analyzed; regions with smaller gradients correspond to lower sensitivity of performance to deviations from the operating condition. The optimal operating points under different heat source conditions are connected to form the optimal operating curve. In actual ship operation, when the main engine load is 50%, the optimal evaporation pressure may be 0.5 MPa corresponding to an evaporation temperature of 65°C; when the load increases to 75%, the optimal evaporation pressure rises to 0.6 MPa corresponding to an evaporation temperature of 72°C; and when the load reaches 100%, the optimal evaporation pressure further increases to 0.7 MPa corresponding to an evaporation temperature of 80°C. The curve connecting these optimal operating points reflects how pressure and temperature should be adjusted in a coordinated manner. The optimal operating curve reflects the best pressure-temperature matching relationship that the system should select under different operating conditions.

[0041] Pressure upper and lower limit constraints are constructed based on the optimal operating curve. Pressure values ​​at each operating point on the optimal operating curve are extracted to identify the pressure variation range and distribution characteristics. The highest and lowest pressure values ​​on the curve are analyzed; these two extreme values ​​initially define the feasible pressure domain. Considering equipment safety margins and control stability requirements, the pressure extreme values ​​are corrected and adjusted. A certain margin is reduced from the highest pressure to serve as the upper limit of actual operating pressure, ensuring the equipment operates within the safety margin. A certain margin is increased from the lowest pressure to serve as the lower limit of actual operating pressure, preventing excessive degradation of system performance. The operating characteristics corresponding to the upper pressure limit are analyzed, including the corresponding temperature, enthalpy, and expected system performance. The operating characteristics corresponding to the lower pressure limit are also analyzed to ensure that the lower limit operating conditions still meet the minimum performance requirements. Mathematical expressions for the pressure upper and lower limit constraints are established in the form P_min ≤ P ≤ P_max, where P_min is the lower pressure limit and P_max is the upper pressure limit. The rationality of the pressure constraints is verified to ensure that the constraint range covers the main operating conditions.

[0042] The pressure slip range is generated by evaluating the sliding pressure tolerance using upper and lower pressure limits. The difference between the upper and lower pressure limits is obtained, reflecting the maximum allowable pressure variation of the system. The relationship between the pressure variation range and the system's dynamic performance is analyzed; a larger variation range indicates stronger system load adaptability. The impact of pressure slip on key components, including the performance of pumps, expanders, and heat exchangers, is assessed. The pressure variation range that each component can adapt to is determined through component characteristic curve analysis. Bottleneck components limiting the sliding pressure tolerance are identified; typically, the expander is most sensitive to pressure changes. The system's sliding pressure tolerance is adjusted based on the allowable pressure range of the bottleneck component. In marine organic Rankine cycle systems, if the inlet pressure of the screw expander fluctuates by more than 20% of the rated pressure, it may cause changes in the rotor-casing clearance, affecting sealing performance. Therefore, even if a larger pressure slip range is allowed on the heat source side, it needs to be limited according to the expander's tolerance. The adjusted sliding pressure tolerance is converted into a specific pressure slip range. The rated operating pressure is set as the midpoint between the upper and lower pressure limits, and slip margins are set both upwards and downwards based on this rated pressure. The final determined pressure sliding range satisfies both performance optimization requirements and equipment safety and stability requirements.

[0043] Dynamic operating condition trajectories are generated by tracking evaporation temperature within the pressure sliding range. Based on the upper and lower limits of the pressure sliding range, the corresponding temperature ranges are queried using the working fluid saturation properties. The saturation temperature corresponding to the upper pressure limit is obtained as the upper boundary of the temperature tracking, and the saturation temperature corresponding to the lower pressure limit is obtained as the lower boundary. The dynamic changes in pressure and temperature during actual operation are analyzed, and the time series of pressure-temperature data points is recorded. The dynamic operating condition trajectory is plotted using the measured pressure and temperature data points. The operating modes of the dynamic trajectory are identified, including steady-state operation, ramp-up operation, and load reduction operation. During steady-state operation, the trajectory fluctuates slightly around the set operating point; during ramp-up operation, the trajectory moves along the direction of increasing pressure and temperature; and during load reduction operation, the trajectory moves along the direction of decreasing pressure and temperature. In actual ship operation, when the main engine switches from low-speed to high-speed navigation, the exhaust temperature and flow rate increase rapidly. The increased heat absorption by the evaporator causes the evaporation pressure and temperature to rapidly climb along the dynamic trajectory. The slope of the trajectory reflects the system's response speed to load changes.

[0044] The dynamic operating condition trajectory is synchronously matched with the heat grade to obtain an adaptive temperature band. Temperature data sequences and corresponding time labels are extracted from the dynamic operating condition trajectory. Temperature change characteristics of heat sources at each heat grade are obtained, including average temperature, temperature fluctuation amplitude, and temperature change frequency. The high-temperature characteristics of the first-grade heat source are analyzed; its temperature typically remains at a high level with relatively small fluctuations. The mid-temperature characteristics of the second-grade heat source are analyzed; the temperature level is moderate but may have significant fluctuations. The low-temperature characteristics of the third-grade heat source are analyzed; the temperature is low and easily affected by the environment. The temperature range of the dynamic operating condition trajectory is matched and compared with the temperature range of each heat grade. The temperature range where the trajectory temperature best matches the heat source temperature is identified, within which the heat source can stably and efficiently transfer heat to the working fluid. For the first-grade heat source, the main engine exhaust heat source, its temperature is stable in the high-temperature range; the corresponding high-temperature range in the dynamic trajectory is selected as the matching temperature band. For the second-grade heat source, the cylinder liner water heat source, its temperature fluctuates in the mid-temperature range; the corresponding mid-temperature range in the dynamic trajectory is selected as the matching temperature band. For lubricating oil heat sources with a third-grade heat quality, the temperature is relatively low. The corresponding low-temperature range in the dynamic trajectory is selected as the matching temperature band. The upper and lower boundaries of the adaptive temperature band are established, with the upper boundary being the highest temperature in the matching temperature band and the lower boundary being the lowest temperature in the matching temperature band.

[0045] Low-temperature evaporation parameters are extracted based on the adaptive temperature band. The maximum operating temperature of the evaporator is determined based on the upper boundary value of the temperature band. The minimum operating temperature of the evaporator is determined based on the lower boundary value of the temperature band. The recommended operating temperature of the evaporator is determined using the center temperature value of the temperature band. The temperature parameters are converted to corresponding pressure parameters using the temperature-pressure saturation relationship. The rated evaporation pressure is retrieved based on the recommended operating temperature, the upper pressure limit is retrieved based on the maximum operating temperature, and the lower pressure limit is retrieved based on the minimum operating temperature. The enthalpy variation range within the adaptive temperature band is analyzed to obtain the corresponding available enthalpy drop and theoretical cycle efficiency. The superheat setpoint is determined based on the position and width of the temperature band. A larger superheat is used in the high-temperature band to improve work capacity, while a smaller superheat is used in the low-temperature band to reduce heat loss. In low-temperature marine operation, when the ambient temperature is low, the adaptive temperature band shifts towards the high-temperature side to compensate for heat loss from the environment, and the superheat setpoint is correspondingly reduced to prevent the working fluid from being overheated and degrading. The extracted low-temperature evaporation parameters, including key operating parameters such as evaporation temperature, evaporation pressure, superheat, and heat load, are summarized to form a complete set of operating parameters.

[0046] A graded evaporation control sequence was constructed based on the parameters of low-temperature evaporation. A segmented control strategy was established based on the differences in operating parameters between the preheating, boiling, and superheating sections. For the preheating section, a first-level control sequence was set, with the control objective being to heat the working fluid from the inlet temperature to the saturation temperature. The control variables were the heat source flow rate of the preheater and the working fluid flow rate. For the boiling section, a second-level control sequence was set, with the control objective being to maintain stable evaporation pressure and temperature. The control variables were the heat source temperature of the evaporator and the working fluid circulation pump speed. For the superheating section, a third-level control sequence was set, with the control objective being to achieve the set superheat. The control variables were the heat source flow rate of the superheater and the steam flow rate. The start-up sequence and switching conditions for each level of the control sequence were established. The system automatically switches to the boiling section after the preheating section is completed, and the superheating section control is activated after the boiling section stabilizes. The response time for each level of control was set: 1-2 minutes for the preheating section, 30-60 seconds for the boiling section, and 20-40 seconds for the superheating section. The system outputs the target parameters corresponding to each control sequence level. The preheating section outputs the saturation temperature and pressure of the working fluid, the boiling section outputs the evaporation pressure and temperature, and the superheating section outputs the set temperature, pressure, and expected flow rate of the superheated steam. These parameters serve as the input basis for turbine operation adjustment.

[0047] Step S140: Adjust turbine operating parameters according to the staged evaporation control sequence to obtain turbine exhaust steam flow, liquefy and cool the turbine exhaust steam flow to obtain condensate working fluid flow, pressurize and reinject the condensate working fluid flow to form circulating working fluid flow, and generate circulating stability parameters based on circulating working fluid flow detection and circulating pressure.

[0048] Specifically, turbine exhaust flow is obtained by adjusting turbine operating parameters according to the staged evaporation control sequence. Output parameters for the superheated section control are extracted from the staged evaporation control sequence, including the temperature, pressure, and expected flow rate of the superheated steam. The turbine inlet pressure parameter is set based on the superheated steam pressure value; higher pressure corresponds to a larger turbine expansion ratio. The turbine inlet temperature parameter is set based on the superheated steam temperature value; higher temperature corresponds to a greater heat load on the turbine blades. The turbine load parameters are adjusted using the superheated steam flow rate information; increasing the flow rate requires increasing the turbine speed to maintain stable operation. The response time requirements in the staged evaporation control sequence are analyzed to determine the speed of turbine parameter adjustment. Control sequences with shorter response times require rapid turbine response to load changes, while sequences with longer response times allow for smooth turbine transitions. The turbine operating mode is selected based on the type of regulation strategy, including constant pressure operation mode, constant speed operation mode, and sliding pressure operation mode. In a marine organic Rankine cycle system, when the main engine transitions from low load to high load, the pressure and flow rate of superheated steam generated by the evaporator rise rapidly. Upon receiving control sequence signals, the turbine control system gradually opens the steam inlet valves and simultaneously adjusts the generator load to ensure a smooth increase in turbine speed to match the increased steam flow. Turbine exhaust is low-pressure superheated steam or saturated steam, typically at a temperature between 40-60°C, and at a pressure below atmospheric pressure, creating a vacuum.

[0049] The turbine exhaust steam is liquefied and cooled to obtain the condensate working fluid. The turbine exhaust steam then enters the condenser for liquefaction and cooling. The condenser uses seawater or fresh water as the cooling medium, transferring the heat of the exhaust steam to the cooling water through heat exchange via the tube walls. The phase change process of the exhaust steam within the condenser is monitored. The exhaust steam first passes through a superheating section to cool to saturation temperature, then enters the condensation section where it changes from a gaseous state to a liquid state. Finally, it passes through a subcooling section for further cooling, becoming a subcooled liquid, completing the transformation from turbine exhaust steam to the condensate working fluid. Temperature and pressure change curves are recorded during the condensation process. The condensation temperature is affected by the cooling water temperature; the lower the cooling water temperature, the lower the condensation temperature. The condensation pressure corresponds to the condensation temperature; a decrease in temperature leads to a decrease in pressure. In actual ship operation, during summer navigation, the seawater temperature may reach 30°C, at which point the condensation temperature is maintained at 35-40°C. During winter navigation, the seawater temperature may drop to 5°C, and the condensation temperature correspondingly decreases to 10-15°C, with a significant drop in condensation pressure. The adequacy of the condensation effect is analyzed, and the state of the outlet working fluid is used to determine whether liquefaction is complete. Measure the temperature and pressure of the working fluid at the condenser outlet to confirm that the working fluid has completely turned into a liquid. The subcooling at the condenser outlet reflects the degree of liquefaction; subcooling is the difference between the outlet liquid temperature and the saturation temperature. A larger subcooling indicates sufficient liquefaction, while a smaller or zero subcooling indicates the possible presence of uncondensed gas. Record the obtained state parameters of the condensate flow, including temperature, pressure, subcooling, and flow rate.

[0050] In some embodiments, the step of pressurizing and reinjecting the condensate flow to form a circulating working fluid flow includes: real-time monitoring of the subcooling of the condensate flow to generate a cavitation risk assessment value; implementing pre-pump pressurization control based on the cavitation risk assessment value to obtain a safe start-up pressure; performing soft-start curve planning on the safe start-up pressure to generate a speed gradient sequence; and using the speed gradient sequence for working fluid delivery to generate a circulating working fluid flow.

[0051] Real-time monitoring of the subcooling of the condensing fluid flow generates a cavitation risk assessment value. Temperature and pressure data of the condensing fluid flow are measured at the condenser outlet. The saturation temperature of the fluid is retrieved from the measured pressure value; this saturation temperature corresponds to the temperature at which the fluid begins to boil under the current pressure. The subcooling value Δt_subcool = t_sat - t_actual is obtained, where t_sat is the saturation temperature and t_actual is the actual measured temperature. The magnitude and temporal variation characteristics of the subcooling are analyzed. A larger subcooling indicates that the liquid is far from saturation, with a lower cavitation risk. A smaller subcooling indicates that the liquid is close to saturation, with a higher cavitation risk. Zero or negative subcooling indicates the presence of bubbles, with an extremely high cavitation risk. The amplitude and frequency of subcooling fluctuations are monitored. Drastic subcooling fluctuations indicate an unstable condensation process, increasing the likelihood of cavitation. In marine organic Rankine cycle systems, insufficient condenser cooling water supply or a sudden increase in cooling water temperature deteriorates the condensation effect, leading to a rise in the outlet working fluid temperature and a rapid decrease in subcooling, sometimes approaching zero. If the circulating pump continues to operate under these conditions, cavitation will occur due to excessively low inlet pressure, resulting in pump vibration, noise, and performance degradation. A cavitation risk assessment model is established, mapping subcooling values ​​to risk levels. Subcooling greater than 10°C is assessed as low risk, 5-10°C as medium risk, and less than 5°C as high risk. Cavitation risk assessment values ​​are generated, ranging from 0 to 1, with higher values ​​indicating higher risk.

[0052] Pre-pump pressurization control is implemented based on cavitation risk assessment values ​​to obtain a safe start-up pressure. The necessity and magnitude of pre-pump pressurization are determined according to the magnitude of the cavitation risk assessment value. When the risk assessment value is in the low-risk range, the pump can be started directly without additional pressurization. When the risk assessment value is in the medium-risk range, moderate pressurization is required to increase the pump inlet pressure. When the risk assessment value is in the high-risk range, significant pressurization or delayed start-up is required to wait for subcooling to recover. Pre-pump pressurization control is implemented by installing a pressurization device in the pump inlet pipeline or adjusting the system pressure to improve the pump inlet conditions. The pressurization device can take the form of an auxiliary pump or a pressure booster tank. By adjusting the output pressure of the pressurization device, the pump inlet pressure meets the net positive suction head (NPSH) requirement. NPSH is the difference between the pump inlet pressure and the saturation pressure; the larger the difference, the more sufficient the NPSH. The required NPSH_required value for the circulating pump is queried; this value is provided by the pump manufacturer. Ensure that the actual net positive suction head (NPSH_available) is greater than the required NPSH, typically requiring a safety margin of NPSH_available > NPSH_required + 0.5 meters of water column. In marine organic Rankine cycle systems, when starting the system from a stopped state, the working fluid temperature may be close to ambient temperature, leading to insufficient subcooling. In this case, first start the auxiliary booster pump to pressurize the working fluid in the storage tank and send it to the inlet of the main circulation pump, increasing the inlet pressure before starting the main circulation pump to avoid the risk of cavitation during startup. Obtain a safe startup pressure value that meets the NPSH requirements.

[0053] A soft-start curve is planned to generate a gradual speed change sequence based on the safe start pressure. The minimum inlet pressure requirement for starting the circulating pump is determined based on the safe start pressure. The safe start pressure is set as the trigger condition for the pump start-up procedure; the start-up operation is only allowed when the pump inlet pressure reaches or exceeds the safe start pressure value. The starting speed curve of the circulating pump is planned according to the working fluid state corresponding to the safe start pressure. The soft-start strategy avoids pressure shocks and flow fluctuations caused by sudden pump start-up. The start-up process duration is set, typically 30-120 seconds, determined based on system scale and stability requirements. The start-up time is divided into multiple time periods, each corresponding to a target speed. A sequence of speed increases from zero to rated speed is planned. The initial speed increase is slow to ensure a stable establishment of system pressure. The speed increase rate accelerates in the middle stage, driving a rapid increase in flow. The speed increase slows down in the final stage, smoothly transitioning to steady-state operation. A gradual speed change sequence is generated, containing the target speed values ​​at each time point. The speed sequence can adopt different forms such as linear growth, exponential growth, or S-curve.

[0054] A gradual speed change sequence is used to process the working fluid and generate the circulating working fluid flow rate. This sequence is sent to the variable frequency drive (VFD) controller of the circulating pump. The VFD adjusts the motor's power supply frequency according to the speed command, achieving precise pump speed control. The actual pump speed is monitored, and closed-loop control ensures the actual speed follows the target speed. As the pump speed gradually increases, the working fluid flow rate increases accordingly. The working fluid flow rate at the pump outlet is measured; the flow rate and speed show an approximately linear relationship. The pressure response characteristics during the working fluid transport process are analyzed. The pump outlet pressure increases with the flow rate, eventually stabilizing at the design pressure level. Pressure oscillations or flow pulsations in the piping system are checked; excessive oscillations require adjustment of the speed increase rate. A stable circulating flow of the working fluid is confirmed, with the inlet and outlet flow rates of each device reaching equilibrium. Circulating working fluid flow rate parameters are generated. The circulating working fluid flow rate is the stable flow rate of the working fluid in the entire closed-loop circuit, reflecting the continuous circulation capability formed by the working fluid passing through the evaporator, turbine, condenser, and circulating pump sequentially. The circulating working fluid flow rate values ​​during stable operation are recorded, including mass flow rate and corresponding volumetric flow rate. Once the circulating pump completes its soft start and reaches its rated speed, the working fluid continues to circulate at a stable flow rate, forming a closed-loop process where the fluid is pressurized by the pump, enters the evaporator for heating and vaporization, and then returns to the condenser after being expanded by the turbine.

[0055] Circulation stability parameters are generated based on circulating working fluid flow rate and circulating pressure. Pressure detection requirements at key locations are determined according to the circulating working fluid flow rate. When the circulating working fluid flow rate is high, the pressure level at various points in the system is high, and the pressure detection range is adjusted upwards accordingly. When the circulating working fluid flow rate is low, the pressure level at various points in the system is low, and the pressure detection range is adjusted downwards accordingly. Based on the fluctuation characteristics of the circulating working fluid flow rate, the pressure monitoring sampling frequency is set; when flow rate fluctuations are frequent, the pressure sampling frequency is increased to capture dynamic changes. The turbine inlet pressure, turbine outlet pressure, evaporator pressure, condenser pressure, and pump outlet pressure in the circulation loop are monitored. The correlation between the pressure at each measuring point and the circulating working fluid flow rate is analyzed; pressure increases with increasing flow rate and decreases with decreasing flow rate. Key factors affecting circulation stability are identified, including heat source temperature fluctuations, cooling water temperature changes, sudden load changes, and working fluid flow rate fluctuations. When encountering wind and waves during ship navigation, the hull rolling causes uneven distribution of the working fluid in the pipeline, resulting in periodic fluctuations in circulating flow rate and pressure. In this case, frequency conversion control of the circulating pump and turbine regulating valve control are used to suppress the fluctuation amplitude. Generate a cyclic stability parameter dataset, extract the turbine inlet pressure as a key parameter for turbine operation, and record its target value, real-time measured value, and fluctuation range. Extract turbine speed as a core parameter for power output, and record its rated value, actual operating value, and fluctuation amplitude. Extract turbine load as an important parameter for power output, and record its setpoint, current load value, and rate of change.

[0056] Step S150: Generate the turbine rotor gravity offset based on the cycle stability parameters and the ship attitude angle. Use the gravity offset to adjust the electromagnetic forces in each axis of the magnetic levitation to form a tilt compensation state. Based on the tilt compensation state, perform thermal efficiency analysis on the flow rate of the circulating working fluid to identify the efficiency loss area. Extract recoverable waste heat in the efficiency loss area to optimize the cycle parameters and generate power generation control commands.

[0057] Specifically, the turbine rotor gravity offset is generated based on cyclic stability parameters combined with the ship's attitude angles. Key operational data such as turbine inlet pressure, turbine speed, and turbine load are extracted from the cyclic stability parameters. Real-time measurements of roll, pitch, and bow angles are extracted from the ship's attitude angle data. The changes in the turbine rotor's gravity distribution under different attitude angles are analyzed. When the ship remains level, the rotor gravity is uniformly distributed along the axial direction, and the radial gravity load on the magnetic levitation system is symmetrical. When the ship rolls, the rotor gravity produces an offset component in the horizontal plane, and the originally symmetrical gravity distribution becomes an asymmetrical distribution. When the ship pitches, the rotor gravity shifts forward and backward along the axial direction, and the load on the front and rear ends of the magnetic levitation bearings differs. In actual ship navigation, when encountering cross waves that cause the ship to tilt 15 degrees to the port side, the turbine rotor's gravity will shift to the left. The electromagnet on the left side of the magnetic levitation system needs to increase its attraction to balance the increased gravity component, while the attraction requirement of the electromagnet on the right side decreases accordingly. A method for calculating gravity offset is established. The gravity offset in the horizontal plane is determined based on the roll angle, and the gravity offset in the axial direction is determined based on the pitch angle. The formula for calculating gravity offset is ΔF = m × g × sin(θ), where ΔF is the gravity offset, m is the rotor mass, g is the gravitational acceleration, and θ is the attitude angle.

[0058] In some embodiments, adjusting the electromagnetic forces along each axis of the magnetic levitation using the gravity offset to form a tilt compensation state includes: using the gravity offset to analyze unbalanced torque identification and establish a rotor eccentricity compensation strategy; using the rotor eccentricity compensation strategy to determine the dominant shaft and auxiliary shaft; performing layered current distribution on the dominant shaft and auxiliary shaft to generate graded compensation current; and using the graded compensation current to construct a tilt compensation state.

[0059] A rotor eccentricity compensation strategy is established by analyzing the unbalanced torque using gravity offset analysis. The unbalanced torque acting on the rotor is analyzed based on gravity offset data. Gravity offset causes the rotor's center of mass to deviate from the center of rotation, generating an eccentric torque acting on the rotor. The magnitude of the eccentric torque is equal to the product of the gravity offset and the eccentric distance, and its direction is perpendicular to the offset direction. The impact of the eccentric torque on rotor operation is analyzed. The eccentric torque causes the rotor to tilt, and the magnetic levitation bearing needs to provide a restoring torque to balance the eccentric torque. The magnitude and direction of the eccentric torque differ in different axes, requiring differentiated compensation strategies. The main planes of action of the eccentric torque are identified. When the roll angle is large, the eccentric torque in the horizontal plane dominates. When the pitch angle is large, the eccentric torque in the longitudinal plane dominates. In actual ship navigation, roll is usually more severe than pitch, especially under cross-wave conditions, where the hull may experience large-amplitude periodic roll. In this case, the eccentric torque in the X-axis direction is the largest and requires focused compensation. A rotor eccentricity compensation strategy is established, the core of which is to distribute the compensation force along each axis according to the magnitude and direction of the eccentric torque. Axis axes with larger eccentric torques receive more compensation force, while those with smaller eccentric torques receive less. The compensation force is achieved by adjusting the electromagnetic force distribution of the electromagnetic bearings.

[0060] For example, determining the dominant axis and auxiliary axis using the rotor eccentricity compensation strategy includes: evaluating the control contribution of each axis based on the rotor eccentricity compensation strategy to determine the axial weight, wherein the control contribution includes torque contribution rate, response time and energy consumption ratio; setting a priority division threshold according to the axial weight; and performing axial priority allocation processing using the priority division threshold to generate the dominant axis and auxiliary axis.

[0061] The axial weights are determined by evaluating the control contribution of each axis based on the rotor eccentricity compensation strategy. Torque compensation requirement data for each axis is extracted from the rotor eccentricity compensation strategy. The required compensation torque values ​​for the X, Y, and Z axes are obtained. The torque contribution rate is obtained by comparing the compensation torque of each axis with the total compensation torque. The X-axis torque contribution rate equals the X-axis compensation torque divided by the sum of the compensation torques of the three axes. The torque contribution rate reflects the magnitude of each axis's role in balancing the rotor eccentricity; a higher contribution rate indicates a more important role. The response time characteristics of the control system for each axis are analyzed. Response time is the time delay from issuing the control command to the electromagnetic force reaching the set value. The actual response time of the magnetic levitation controller for each axis is measured. Axis axes with shorter response times can quickly adjust the compensation force, suitable for handling rapidly changing eccentric disturbances. Axis axes with longer response times adjust more slowly, suitable for handling gradually changing eccentric disturbances. In a marine organic Rankine cycle turbine, the X-axis controller uses a high-speed DSP chip with a response time of approximately 5 milliseconds, the Y-axis controller has a response time of approximately 8 milliseconds, and the Z-axis controller has a response time of approximately 10 milliseconds, with response speeds ordered from fastest to slowest as XYZ. The energy consumption ratio of each axis is analyzed. The energy consumption ratio is the ratio of the electrical power consumed by the electromagnets in each axis to the total electrical power of the system. Axis axes with high torque compensation requirements typically have higher energy consumption. The energy consumption ratio reflects the impact of each axis on the system's energy consumption. The control contribution of each axis is determined by considering the torque contribution rate, response time, and energy consumption ratio. A control contribution evaluation formula is established: C = α × M_ratio + β / T_response - γ × E_ratio, where M_ratio is the torque contribution rate, T_response is the response time, E_ratio is the energy consumption ratio, and α, β, and γ are weighting coefficients. The axis weights are determined based on the magnitude of the control contribution of each axis. Axis axes with high control contributions are assigned larger weights, and axes with low control contributions are assigned smaller weights.

[0062] Set the priority division threshold according to the axial weights. Obtain the maximum, minimum, and average values of the axial weights. Determine the benchmark for priority division based on the statistical characteristics of the weight values. Analyze the distribution range and dispersion degree of the weight values. The greater the weight difference, the more obvious the difference in the control importance of each axis. Set the priority division threshold, which is calculated by the weighted average of the weight average and the maximum value. The threshold calculation formula is W_threshold = 0.6×W_avg + 0.4×W_max, where W_threshold is the priority division threshold, W_avg is the axial weight average, and W_max is the axial weight maximum. The coefficients 0.6 and 0.4 in the formula reflect the degree of the threshold bias towards the average value, making the threshold in a moderate position. The axes with weights exceeding the threshold are classified as high-priority, and the axes with weights lower than the threshold are classified as low-priority. Analyze the rationality of the threshold setting, and verify whether the threshold position is appropriate by estimating the division results. Too high a threshold will result in all axes being classified as low-priority, losing the meaning of priority distinction. Too low a threshold will result in multiple axes being classified as high-priority simultaneously, unable to highlight the control focus. Adjust the threshold position so that the number of high-priority axes is reasonable, usually controlled at one or two axes.

[0063] Implement axial priority allocation processing using the priority division threshold to generate the main axis and the auxiliary axis. Compare the axial weights with the priority division threshold. Extract the X-axis weight W_X and compare it with the threshold W_threshold. When W_X > W_threshold, the X-axis is allocated as the high-priority main axis. Extract the Y-axis weight W_Y and compare it with the threshold. When W_Y > W_threshold, the Y-axis is allocated as the high-priority main axis or the secondary main axis. Extract the Z-axis weight W_Z and compare it with the threshold. When W_Z < W_threshold, the Z-axis is allocated as the low-priority auxiliary axis. Establish the priority index P_index = W_axis / W_threshold. The axes with a priority index greater than 1 are the main axes, and those less than 1 are the auxiliary axes. When the ship rolls and pitches simultaneously, the weights of the X-axis and the Y-axis may both exceed the threshold to become double main axes, jointly coping with the compound eccentricity, while the Z-axis, as the auxiliary axis, provides vertical support. Establish the configuration relationship between the main axis and the auxiliary axis. The main axis is responsible for the main eccentricity compensation task, and the control resources are preferentially allocated. The auxiliary axis is responsible for the auxiliary balance task, and the control resources are allocated as needed.

[0064] A tiered current distribution system is implemented for the dominant and auxiliary axes to generate graded compensation currents. A current distribution strategy is designed based on the compensation force requirements of the dominant and auxiliary axes. The compensation force is provided by the electromagnetic force of an electromagnet, the magnitude of which is determined by the current intensity. A correspondence between current and electromagnetic force is established, with the electromagnetic force proportional to the square of the current. Two layers are set up for the dominant axis: a basic compensation current layer and a dynamically adjustable current layer. The basic compensation current layer provides a constant compensation force to handle the average eccentric torque. The dynamically adjustable current layer provides rapidly changing compensation force to handle fluctuations in the eccentric torque. A single compensation current layer is set up for the auxiliary axis to provide stable auxiliary compensation force. The value of the basic compensation current for the dominant axis is obtained, corresponding to the compensation force required for the average eccentric torque of the dominant axis. The range of the dynamic adjustable current for the dominant axis is obtained, covering the amplitude of eccentric torque fluctuations. The value of the compensation current for the auxiliary axis is obtained, corresponding to the compensation force required for the eccentric torque of the auxiliary axis.

[0065] A graded compensation current is used to construct a tilt compensation state. This graded compensation current configuration is applied to the magnetic levitation control system. The control system adjusts the power supply current of each electromagnet according to the current setpoint. The electromagnet on the main shaft first applies a basic compensation current to establish a basic compensation force field. Based on this basic compensation force field, a dynamic adjustment current is superimposed to cope with the real-time changing eccentric torque. The electromagnets on the auxiliary shafts apply corresponding compensation currents to provide auxiliary balancing forces. The position response of the rotor along each axis is monitored. Under the action of the graded compensation current, the rotor gradually adjusts its position towards the geometric center of the magnetic levitation bearing. The position deviation of each axis is checked to see if it converges to the allowable range. The position deviation of the main shaft should be less than 10% of the bearing clearance, and the position deviation of the auxiliary shaft should be less than 15% of the bearing clearance. The stability of the compensation effect is verified. The fluctuation of the position deviation is observed over a continuous period; fluctuations remaining within a small range indicate a stable compensation effect. When the position deviations of each axis meet the requirements and remain stable, the system is confirmed to have successfully constructed a tilt compensation state. In the tilt compensation state, the rotor runs smoothly with low vibration levels, and the load distribution of the magnetic levitation bearing is reasonable.

[0066] In some embodiments, the step of performing thermal efficiency analysis on the circulating working fluid flow rate based on the tilt compensation state to identify efficiency loss regions includes: determining a rotor operating stability benchmark through the tilt compensation state; performing enthalpy change tracking on the circulating working fluid flow rate based on the rotor operating stability benchmark to generate energy conversion characteristics; evaluating the energy conversion characteristics in segments to form an efficiency distribution map; and determining the efficiency loss region based on the efficiency distribution map.

[0067] The rotor's operational stability benchmark is determined through tilt compensation. Rotor operating parameters, including axial position deviations, vibration amplitude, and speed stability, are extracted from the tilt compensation state. The rotor position deviations are analyzed to ensure they remain within allowable ranges. Axial position deviations less than set thresholds indicate stable rotor positioning. The rotor vibration level is analyzed to ensure it is within normal ranges. Vibration amplitudes below limits indicate smooth and normal rotor operation. Speed ​​stability is analyzed to ensure it meets requirements. Speed ​​fluctuations less than 1% of the rated speed indicate stable speed. In marine organic Rankine cycle turbines, when the tilt compensation system is effectively operating, even when the hull is in a rolling state, the turbine rotor's radial displacement can be controlled within 0.1 mm, vibration acceleration below 5 m / s², and speed fluctuations within ±30 rpm. These indicators collectively constitute the rotor's operational stability benchmark. Criteria for establishing the rotor's operational stability benchmark are established, including position deviation limits, vibration limits, and speed fluctuation limits. Meeting all criteria confirms rotor operational stability, allowing for reliable thermal efficiency analysis.

[0068] Energy conversion characteristics are generated by tracking the enthalpy change of the circulating working fluid flow rate based on the rotor's stable operation benchmark. Under the premise of stable rotor operation, the energy conversion process of the circulating working fluid is tracked in detail. Circulating working fluid flow data and state parameters of each stage are used as the tracking basis. A general method for enthalpy change tracking is established. By measuring the temperature and pressure at the inlet and outlet of each stage, the corresponding specific enthalpy value is obtained by consulting the thermodynamic property table of the working fluid, and thus the enthalpy change is obtained. The enthalpy change process of the working fluid in the evaporator is tracked, and the evaporator enthalpy rise Δh_evap = h_out - h_in is obtained. The enthalpy change process of the working fluid in the turbine is tracked, and the turbine enthalpy drop Δh_turb = h_in - h_out is obtained. The enthalpy change process of the working fluid in the condenser is tracked, and the condenser enthalpy drop Δh_cond = h_in - h_out is obtained. The enthalpy change process of the working fluid in the circulating pump is tracked, and the pump enthalpy rise Δh_pump = h_out - h_in is obtained. In the above formula, h_in and h_out represent the specific enthalpy values ​​at the equipment inlet and outlet, respectively. Enthalpy rise indicates energy absorption by the working fluid, and enthalpy drop indicates energy release. In actual ship operation, by comprehensively measuring the state changes of the working fluid at each stage, a complete enthalpy-entropy diagram can be plotted. The lines connecting the points on the diagram reflect the thermodynamic process of the cycle, the length of each line segment reflects the magnitude of energy conversion, and the area of ​​the diagram's envelope reflects the net work output. Energy conversion characteristic data is generated, including the enthalpy change values ​​and directions at each stage.

[0069] The energy conversion characteristics are evaluated in segments to form an efficiency distribution map. Based on the enthalpy change direction in the energy conversion characteristics, the cycle process is divided into four basic segments: heat absorption, power generation, heat release, and power consumption. The heat absorption segment corresponds to the evaporator operation process, and the heat absorption efficiency is evaluated. The evaporator enthalpy change value Δh_evap is extracted, and the heat absorption efficiency is obtained by the ratio of the actual enthalpy change to the theoretically achievable enthalpy change. The power generation segment corresponds to the turbine operation process, and the power generation efficiency is evaluated. The turbine enthalpy change value Δh_turb is extracted, and the power generation efficiency is obtained by the ratio of the actual enthalpy drop to the theoretical isentropic enthalpy drop. The heat release segment corresponds to the condenser operation process, and the heat release efficiency is evaluated. The condenser enthalpy change value Δh_cond is extracted to evaluate the completeness of the condensation process. The power consumption segment corresponds to the circulating pump operation process, and the pump efficiency is evaluated. The pump enthalpy change value Δh_pump is extracted, and the pump efficiency is obtained by the ratio of the theoretical power consumption to the actual power consumption. The efficiency values ​​for each segment are obtained, and the spatial distribution characteristics of the efficiency are analyzed. Arrange the efficiencies of each segment in cyclic order to form an efficiency distribution sequence. Plot an efficiency distribution graph, with the horizontal axis representing each segment of the cyclic process and the vertical axis representing the efficiency value. The graph visually illustrates the differences and trends in efficiency across each segment. In a marine organic Rankine cycle, a typical efficiency distribution graph shows evaporator efficiency at 85%-90%, turbine efficiency at 75%-82%, condenser efficiency at 90%-95%, and circulating pump efficiency at 65%-75%, indicating that the turbine and pump are relatively inefficient components.

[0070] Based on the efficiency distribution map, determine the efficiency loss areas. Analyze the segments and locations with low efficiency in the efficiency distribution map. Extract the efficiency values ​​of each segment and compare them with the corresponding design efficiency values. Obtain the efficiency deviation of each segment and establish the deviation calculation formula η_deviation=(η_design-η_actual) / η_design×100%, where η_design is the design efficiency value and η_actual is the actual measured efficiency value. Set the judgment criteria for efficiency loss; segments with an efficiency deviation greater than 5% are marked as efficiency loss areas. Identify the areas in the map that meet the judgment criteria. Turbine efficiency below 77% is marked as a turbine efficiency loss area. Evaporator efficiency below 80% is marked as an evaporator efficiency loss area. Circulating pump efficiency below 60% is marked as a pump efficiency loss area. In actual ship operation, when the turbine operates under low load conditions, the reduced steam flow leads to a decrease in efficiency, and obvious dips will appear on the efficiency distribution map. The severity of the loss can be quantified by calculating the deviation. Analyze the causes and effects of the efficiency loss areas. Turbine efficiency losses may be caused by incomplete expansion, mechanical friction, or steam leakage. Evaporator efficiency losses may be caused by excessive heat exchange temperature differences, reduced heat transfer coefficients, or fouling. Pump efficiency losses may be caused by operating conditions deviating from the design point, cavitation, or mechanical wear.

[0071] In the efficiency loss region, recoverable waste heat is extracted to optimize cycle parameters and generate power generation control commands. Waste heat recovery potential analysis is performed for the identified efficiency loss regions. In the evaporator efficiency loss region, the presence of underutilized heat sources is analyzed. If the exhaust temperature of the heat source remains high, it indicates that the waste heat is not fully absorbed; utilization can be improved by increasing the heat exchange area or extending the heat exchange time. In the turbine efficiency loss region, it is analyzed whether the turbine exhaust still carries considerable heat. If the turbine exhaust temperature is significantly higher than the condensing temperature, it indicates the presence of recoverable waste heat, which can be recovered and utilized by adding a regenerator. In the condenser region, it is analyzed whether the heat released during condensation can be recovered and utilized. When the condensing temperature is high, the condensing heat can be used for low-temperature heating applications such as heating or seawater desalination. Recoverable waste heat is extracted from each efficiency loss region, obtained through temperature, flow rate, and specific heat capacity. In a marine organic Rankine cycle system, when a low evaporator outlet steam temperature leads to a decrease in turbine efficiency, the heat source flow rate can be increased or the evaporation pressure increased to raise the steam temperature and improve work capacity. Based on the distribution and quantity of recoverable waste heat, the cycle operation parameters are optimized. Evaporation temperature and pressure are increased to enhance cycle efficiency, working fluid flow rate is adjusted to match heat source supply, and condensation temperature is adjusted to balance system performance and waste heat utilization. Finally, power generation control commands are generated, including setpoints for control variables such as turbine inlet valve opening, circulating pump speed, generator load, and heat source flow rate, completing the multi-source coordinated recovery of waste heat.

[0072] To implement the low-temperature waste heat power generation method based on the organic Rankine cycle corresponding to the above method embodiments, and to achieve the corresponding functions and technical effects. See also Figure 2 , Figure 2 A structural block diagram of a cryogenic waste heat power generation device 200 based on an organic Rankine cycle according to an embodiment of this application is shown. For ease of explanation, only the parts relevant to this embodiment are shown. The cryogenic waste heat power generation device 200 based on an organic Rankine cycle according to an embodiment of this application includes: Signal acquisition module 201 is used to acquire temperature signals and hull attitude angles of waste heat sources from main and auxiliary engines of ships, perform graded heat capacity analysis on the temperature signals to identify heat grade levels, and establish graded configuration of heat sources based on the heat grade levels. Anti-deviation control module 202 is used to identify liquid deviation areas based on the heat source classification configuration and the ship attitude angle, adjust the working fluid distribution ratio of each section based on the liquid deviation area to form anti-deviation parameters, perform working fluid performance monitoring and locate degradation products according to the anti-deviation parameters, and collect the purity deviation of the degradation products to map the working fluid circulation status. Evaporation optimization module 203 is used to perform evaporation classification analysis to identify pressure boundary points for the working fluid circulation state, extract the available enthalpy drop of the pressure boundary points, determine low-temperature evaporation operating parameters through the available enthalpy drop and the heat grade, and construct a graded evaporation control sequence based on the low-temperature evaporation operating parameters; The circulation drive module 204 is used to adjust the turbine operating parameters according to the staged evaporation control sequence to obtain the turbine exhaust steam flow, liquefy and cool the turbine exhaust steam flow to obtain the condensate working fluid flow, pressurize and reinject the condensate working fluid flow to form the circulating working fluid flow rate, and detect the circulating pressure based on the circulating working fluid flow rate to generate the circulating stability parameters. The tilt compensation module 205 is used to generate a turbine rotor gravity offset based on the cycle stability parameters and the ship attitude angle, adjust the electromagnetic forces of each axis of magnetic levitation using the gravity offset to form a tilt compensation state, perform thermal efficiency analysis on the flow rate of the circulating working fluid based on the tilt compensation state to identify efficiency loss areas, extract recoverable waste heat in the efficiency loss areas to optimize cycle parameters and generate power generation control commands.

[0073] The aforementioned low-temperature waste heat power generation device 200 based on the organic Rankine cycle can implement the low-temperature waste heat power generation method based on the organic Rankine cycle described in the above method embodiments. The options in the above method embodiments are also applicable to this embodiment and will not be detailed here. The remaining content of this application's embodiments can be referred to the content of the above method embodiments, and will not be repeated in this embodiment.

[0074] The purpose of the above embodiments is to reproduce and derive the technical solution of the present invention by way of example, and to fully describe the technical solution, purpose and effect of the present invention. The purpose is to enable the public to have a more thorough and comprehensive understanding of the disclosure of the present invention, and not to limit the scope of protection of the present invention.

[0075] The above embodiments are not an exhaustive list based on the present invention, and there may be many other embodiments not listed. Any substitutions and improvements made without departing from the concept of the present invention are within the protection scope of the present invention.

Claims

1. A low-temperature waste heat power generation method based on the organic Rankine cycle, characterized in that, include: The temperature signals of the waste heat sources of the ship's main and auxiliary engines and the ship's attitude angle are collected. The temperature signals are then subjected to graded heat capacity analysis to identify the heat grade level. The heat source graded configuration is then established based on the heat grade level. Based on the heat source classification configuration and the ship attitude angle, the liquid deviation area is identified. Based on the liquid deviation area, the working fluid distribution ratio of each section is adjusted to form anti-deviation parameters. According to the anti-deviation parameters, the working fluid performance is monitored to locate the degradation products. The purity deviation of the degradation products is collected to map the working fluid circulation status. For the working fluid circulation state, perform evaporation classification analysis to identify the pressure boundary point, extract the available enthalpy drop of the pressure boundary point, determine the low temperature evaporation condition parameters through the available enthalpy drop and the heat grade, and construct a graded evaporation control sequence based on the low temperature evaporation condition parameters; The turbine operating parameters are adjusted according to the staged evaporation control sequence to obtain turbine exhaust flow. The turbine exhaust flow is liquefied and cooled to obtain condensate flow. The condensate flow is pressurized and reinjected to form circulating working fluid flow. The circulating pressure is detected based on the circulating working fluid flow to generate circulating stability parameters. Based on the cycle stability parameters and the ship attitude angle, a turbine rotor gravity offset is generated. The gravity offset is used to adjust the electromagnetic forces in each axis of magnetic levitation to form a tilt compensation state. Based on the tilt compensation state, the thermal efficiency of the circulating working fluid flow rate is analyzed to identify the efficiency loss region. The recoverable waste heat is extracted from the efficiency loss region to optimize the cycle parameters and generate power generation control commands.

2. The method according to claim 1, characterized in that, The step of adjusting the working fluid distribution ratio of each segment based on the liquid offset region to form anti-flow parameters includes: Based on the liquid offset region, liquid surface oscillation frequency analysis is performed to identify resonance risk frequency bands; A damping adjustment scheme for generating flow compensation and allocation is designed for the resonant risk frequency band; Dynamic compensation rules are constructed based on the flow compensation allocation scheme and the liquid offset region; Anti-deviation parameters are established based on the aforementioned dynamic compensation rules.

3. The method according to claim 1, characterized in that, The step of collecting purity deviation data of the degradation products to map the working fluid circulation status includes: Molecular vibrational spectral features were extracted from the degradation products. Degradation type is identified by online spectral comparison based on the aforementioned molecular vibrational spectral characteristics; The degradation type was subjected to concentration quantification to generate purity deviation. The working fluid circulation state is mapped based on the purity deviation.

4. The method according to claim 1, characterized in that, The determination of low-temperature evaporation operating parameters using the available enthalpy drop and the heat grade includes: The available enthalpy drop is used to perform a sliding pressure operation adaptability analysis to extract the pressure sliding range; Dynamic operating condition trajectory is generated by tracking the evaporation temperature within the pressure sliding range. The dynamic operating condition trajectory is synchronously matched with the thermal grade to obtain an adaptive temperature band; Parameters for low-temperature evaporation are extracted based on the adaptive temperature band.

5. The method according to claim 1, characterized in that, The step of pressurizing and reinjecting the condensate flow to form a circulating working fluid flow includes: The subcooling of the condensate flow is monitored in real time to generate a cavitation risk assessment value; Based on the cavitation risk assessment value, implement pre-pump pressurization control to obtain a safe start-up pressure; A soft-start curve planning process is performed on the aforementioned safe start pressure to generate a speed gradient sequence; The working fluid is transported using the aforementioned speed gradient sequence to generate a circulating working fluid flow rate.

6. The method according to claim 1, characterized in that, The method of adjusting the electromagnetic forces along each axis of the magnetic levitation system using the gravity offset to form a tilt compensation state includes: The unbalanced torque is identified and a rotor eccentricity compensation strategy is established using the gravity offset analysis. The rotor eccentricity compensation strategy is used to determine the main shaft and the auxiliary shaft; A hierarchical current distribution is performed between the main axis and the auxiliary axis to generate a graded compensation current. The tilt compensation state is constructed using the graded compensation current.

7. The method according to claim 1, characterized in that, The step of analyzing the thermal efficiency of the circulating working fluid flow rate based on the tilt compensation state to identify efficiency loss regions includes: The rotor's operational stability benchmark is determined by the tilt compensation state. Energy conversion characteristics are generated by tracking the enthalpy change of the circulating working fluid flow rate based on the rotor operation stability benchmark. The energy conversion characteristics are evaluated in segments to form an efficiency distribution map; The efficiency loss region is determined based on the efficiency distribution map.

8. The method according to claim 4, characterized in that, The step of performing sliding pressure operation adaptability analysis on the available enthalpy drop to extract the pressure sliding range includes: The available enthalpy drop is used to couple the heat source and working fluid to obtain the thermodynamic boundary conditions; The optimal operating curve is identified by pressure-temperature co-optimization of the aforementioned thermodynamic boundary conditions; Based on the optimal operating curve, construct upper and lower pressure limits; The pressure sliding range is generated by evaluating the sliding pressure tolerance using the aforementioned upper and lower pressure limits.

9. The method according to claim 6, characterized in that, The determination of the main shaft and auxiliary shaft using the rotor eccentricity compensation strategy includes: The axial weights are determined by evaluating the control contribution of each axis based on the rotor eccentricity compensation strategy. The control contribution includes torque contribution rate, response time and energy consumption ratio. The priority division threshold is set according to the axial weight; The axial priority allocation process is performed using the aforementioned priority division threshold to generate the dominant axis and the auxiliary axis.

10. A low-temperature waste heat power generation device based on the organic Rankine cycle, characterized in that, include: The signal acquisition module is used to acquire temperature signals from the waste heat sources of the ship's main and auxiliary engines and the ship's attitude angle, perform graded heat capacity analysis on the temperature signals to identify heat grade levels, and establish graded configurations of heat sources based on the heat grade levels. The anti-deviation control module is used to identify liquid deviation areas based on the heat source classification configuration and the ship attitude angle, adjust the working fluid distribution ratio of each section based on the liquid deviation area to form anti-deviation parameters, perform working fluid performance monitoring and locate degradation products according to the anti-deviation parameters, and collect the purity deviation of the degradation products to map the working fluid circulation status. The evaporation optimization module is used to perform evaporation classification analysis to identify pressure boundary points for the working fluid circulation state, extract the available enthalpy drop of the pressure boundary points, determine low-temperature evaporation operating parameters through the available enthalpy drop and the heat grade, and construct a graded evaporation control sequence based on the low-temperature evaporation operating parameters. The circulation drive module is used to adjust the turbine operating parameters according to the staged evaporation control sequence to obtain the turbine exhaust steam flow, liquefy and cool the turbine exhaust steam flow to obtain the condensate working fluid flow, pressurize and reinject the condensate working fluid flow to form the circulating working fluid flow rate, and detect the circulating pressure based on the circulating working fluid flow rate to generate circulating stability parameters. The tilt compensation module is used to generate a turbine rotor gravity offset based on the cycle stability parameters and the ship attitude angle, adjust the electromagnetic forces of each axis of magnetic levitation using the gravity offset to form a tilt compensation state, perform thermal efficiency analysis on the flow rate of the circulating working fluid based on the tilt compensation state to identify efficiency loss areas, extract recoverable waste heat in the efficiency loss areas to optimize cycle parameters and generate power generation control commands.

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