Constant-temperature and constant-resistance control system for defrosting of marine air cooler and control method of constant-temperature and constant-resistance control system

Abstract

The invention is suitable for the technical field of marine air coolers, and provides a constant-temperature and constant-resistance control system for defrosting of a marine air cooler and a control method thereof.The constant-temperature and constant-resistance control system comprises an air cooler body, an electric heating module, a sensing module and an intelligent controller, an evaporator fin area is arranged in the air cooler body, and the electric heating module comprises a plurality of independent PTC heating modules; each PTC heating module is transversely inserted into a fin gap of the evaporator fin area to form an independent heating subarea; the intelligent controller is electrically connected with the electric heating module and the sensing module. The intelligent controller receives data of the posture sensing unit, the subarea temperature sensing unit and the electrical safety monitoring unit, differentiated target defrosting temperatures are set for different heating subareas of an evaporator fin area through a dynamic thermal field regulation and control algorithm, and the problem of long-time electric heating defrosting is solved. The insulation resistance value of electric heating is lower than the marine standard; and defrosting dead angles are caused by non-uniform distribution of frost layers when the ship inclines.

Description

Technical Field

[0001] This invention relates to the field of marine air cooler technology, and more specifically, to a constant temperature and constant resistance control system and control method for defrosting marine air coolers. Background Technology

[0002] When marine air coolers are sailing in high-temperature and high-humidity sea areas, the surface of their evaporator fins is prone to rapid frost formation, which seriously affects the heat exchange efficiency. Therefore, defrosting operations must be performed regularly.

[0003] Currently, common defrosting methods mainly include electric defrosting and hot gas defrosting. Among them, electric defrosting is more widely used in practice due to its advantages such as simple system structure and convenient control.

[0004] However, during prolonged defrosting with electric heating, the insulation resistance of the electric heating element is prone to significant attenuation under prolonged high temperature and high humidity defrosting conditions, falling below the minimum limit specified in marine electrical standards and failing to meet the insulation safety requirements of marine equipment.

[0005] Meanwhile, existing electric heating defrosting methods mostly adopt static layout designs, which do not fully consider special working conditions such as continuous heeling, trimming, and rolling of ships during navigation.

[0006] When a ship tilts, the condensate will redistribute due to the change in the direction of gravity, resulting in significant differences in the thickness of the frost layer in different parts of the evaporator. If a uniform heating strategy is adopted, it will inevitably cause the problem of overheating in the thin frost area and incomplete melting in the thick frost area, thus forming a defrosting dead zone. A constant temperature and constant resistance control system and its control method for defrosting marine air coolers are proposed to improve the existing problems. Summary of the Invention

[0007] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a constant temperature and constant resistance control system and control method for defrosting marine air coolers.

[0008] To achieve the above objectives, the present invention provides the following technical solution: a constant temperature and resistance control system for defrosting marine air coolers, comprising: The main body of the air cooler has an evaporator fin area inside.

[0009] An electric heating module, comprising multiple independent PTC heating modules, each of which is laterally inserted into the fin gaps of the evaporator fin area to form its own independent heating zone.

[0010] The sensing module includes: An attitude sensing unit is used to detect the ship's roll and pitch angles in real time.

[0011] A zone temperature sensing unit is provided for each heating zone, and the zone temperature sensing unit is used to detect the actual temperature of the evaporator fins in each zone.

[0012] An electrical safety monitoring unit is used to monitor the insulation resistance of each PTC heating module online.

[0013] An intelligent controller is electrically connected to both the electric heating module and the sensing module. The intelligent controller is configured to receive data from the attitude sensing unit, the zone temperature sensing unit, and the electrical safety monitoring unit.

[0014] Based on real-time attitude data and temperature feedback from each zone, a differentiated target temperature is calculated and set for each heating zone according to a preset dynamic thermal field control algorithm.

[0015] The present invention is further configured such that: the sensing module further includes an auxiliary sensing unit, which is used to measure the absolute humidity difference between the air inlet and the air outlet of the evaporator of the main body of the air cooler.

[0016] The present invention is further configured such that the plurality of PTC heating modules are arranged in a matrix array in the evaporator fin area.

[0017] The main body of the air cooler has several mounting holes on its side plate, and the PTC heating module is fixedly connected to the mounting holes by bolts.

[0018] The PTC heating module includes a heating element, with a set of conductive strips on each side of the heating element, and an insulating film on the side of each set of conductive strips away from the heating element. A sleeve is fitted over the outer side of each set of insulating films.

[0019] The present invention is further configured such that the dynamic thermal field control algorithm is configured to adjust the target temperature of the heating zones at different spatial positions of the evaporator fin area according to the lateral tilt angle and the longitudinal tilt angle.

[0020] In this section, the target temperature is increased for the section located on the side where frost has formed due to the ship's tilt, and decreased for the section located on the opposite side.

[0021] The present invention is further configured such that: the intelligent controller is also configured to perform intelligent defrosting start judgment, the intelligent defrosting start judgment specifically includes: estimating the frost layer thickness and distribution imbalance of each heating zone based on the attitude sensing unit data, zone temperature data, humidity data and wind pressure data.

[0022] The defrost program will be started when any of the following preset defrost start conditions are met: a. The estimated average frost thickness reaches the first thickness threshold.

[0023] b. The distribution imbalance exceeds the imbalance threshold, and the maximum local frost thickness reaches the second thickness threshold.

[0024] Wherein, the second thickness threshold is greater than the first thickness threshold.

[0025] The present invention is further configured such that: the intelligent controller is also configured to perform health management, the health management including: calculating a health index based on the insulation resistance change data of each PTC heating module; when the health of a certain group of PTC heating modules is lower than the warning threshold, automatically adjusting the power of its adjacent PTC heating modules for thermal compensation, and issuing a maintenance warning.

[0026] The intelligent controller is also configured to execute a tiered security policy: When the insulation resistance of any PTC heating module is detected to be lower than the first safety threshold but higher than the second safety threshold, the first-level strategy is executed: reduce the heating power of the PTC heating module and issue an early warning.

[0027] When the power supply falls below the second safety threshold, the second-level strategy is executed: power to the module is cut off.

[0028] The present invention is further configured such that the intelligent controller determines the defrosting is complete under any of the following conditions: a. The actual temperature of all heating zones has reached and stabilized within the preset error band of their respective target temperatures, and has remained stable for a preset period of time.

[0029] b. The total defrosting time reaches the preset maximum safe time.

[0030] The control method for a constant temperature and resistance control system for defrosting marine air coolers, using the aforementioned constant temperature and resistance control system for defrosting marine air coolers, includes the following steps: S0. Based on the attitude sensing unit data, zone temperature data, humidity data and wind pressure data, estimate the frost thickness and distribution imbalance of each heating zone.

[0031] When any of the following preset conditions for defrosting are met, it is determined that defrosting needs to be initiated, and the process proceeds to step S1: a. The estimated average frost thickness reaches the first thickness threshold.

[0032] b. The distribution imbalance exceeds the imbalance threshold, and the maximum local frost thickness reaches the second thickness threshold.

[0033] S1. The intelligent control system performs intelligent defrosting start judgment. When the start conditions are met, it enters the defrosting program and performs system self-check.

[0034] S2. The intelligent controller collects the ship's heel angle, pitch angle, and the actual temperature of each heating zone in real time.

[0035] S3: The intelligent controller calculates the target temperature required for each heating zone based on the dynamic thermal field control algorithm.

[0036] S4. The intelligent controller adjusts the power of each PTC heating module through an independent control loop so that the actual temperature of each zone reaches its target temperature.

[0037] S5. During the defrosting process, the insulation resistance of the electric heating is continuously monitored. If the insulation resistance of any heating zone is lower than the first safety threshold, an alarm safety strategy is triggered.

[0038] S6. When any of the following defrosting completion conditions are met, heating will be stopped and defrosting will end: The intelligent controller determines that defrosting is complete based on any of the following conditions: a. The actual temperature of all heating zones has reached and stabilized within the preset error band of their respective target temperatures, and has remained stable for a preset period of time.

[0039] b. The total defrosting time reaches the preset maximum safe time.

[0040] The present invention is further configured such that the hierarchical security strategy in step S5 includes: When the insulation resistance of any PTC heating module is detected to be lower than the first safety threshold but higher than the second safety threshold, the first-level strategy is executed: reduce the heating power of the PTC heating module and issue an early warning. When it is lower than the second safety threshold, the second-level strategy is executed: cut off the power supply to the module.

[0041] The present invention is further configured to include step S7: recording and analyzing the performance data of each PTC heating module during each defrosting process, updating its health model, and optimizing the power allocation and defrosting start-up strategy for subsequent defrosting cycles based on the health model.

[0042] In summary, this application includes at least one of the following beneficial technical effects: (1) The PTC heating module is easy to install and can be disassembled and replaced at any time; the PTC heating module has constant temperature heating characteristics to achieve the purpose of defrosting. In addition, the intelligent control system monitors the insulation resistance value in the heating zone through a graded safety strategy, so that the insulation resistance value of electric heating is stably maintained above the minimum limit specified by the marine electrical standard, which meets the insulation safety certification requirements of the classification society; the PTC heating module is protected by an external stainless steel sleeve, which increases the service life and allows it to be immersed in water for heating.

[0043] (2) By introducing attitude sensing and dynamic thermal field control, the technical problems of uneven frost layer in various parts of the evaporator caused by ship tilting, low efficiency of traditional uniform heating and easy formation of defrosting dead corners have been solved, thus improving defrosting uniformity and efficiency.

[0044] (3) By designing online insulation resistance monitoring and graded safety strategies, it is possible to provide real-time early warning and handle electrical safety hazards such as leakage of PTC heating modules. Through thermal compensation and thermal field reconstruction functions, it can maintain the basic defrosting capability of the system when some modules fail or are downgraded, thereby improving the safety and reliability of the system.

[0045] (4) It has intelligent defrosting start judgment and health management functions, and can trigger defrosting based on multi-source data. Through long-term tracking and learning of the performance of PTC heating module, it optimizes subsequent control strategies, realizing preventive maintenance and energy efficiency optimization. Attached Figure Description

[0046] Figure 1 This is a schematic diagram of the constant temperature and resistance control system for defrosting marine air coolers in this invention.

[0047] Figure 2 This is a schematic diagram of the PTC heating module in this invention.

[0048] Figure 3 This is a diagram showing the distribution of heating zones in this invention.

[0049] Figure 4 This is a coordinate distribution diagram of the heating zone after normalization in this invention.

[0050] Figure 5 This is a flowchart illustrating the control method of the constant temperature and constant resistance control system for defrosting marine air coolers in this invention.

[0051] Explanation of reference numerals in the attached diagram: 1. Main body of the air cooler; 2. Evaporator fin area; 3. PTC heating module; 31. Sleeve; 32. Insulating film; 33. Heating element; 34. Conductive strip. Detailed Implementation

[0052] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0053] It should be noted that, unless otherwise specified, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0054] Please see Figures 1-5 The present invention provides the following technical solutions: Example 1, see Figure 1 The constant temperature and resistance control system for defrosting marine air coolers includes: air cooler body 1, electric heating module, sensing module and intelligent controller.

[0055] The main body 1 of the air cooler has an evaporator fin area 2 inside. In this embodiment, the main body 1 of the air cooler is a marine corrosion-resistant air cooler, and has a copper-aluminum composite evaporator fin area 2 inside.

[0056] The electric heating module includes multiple independent PTC heating modules 3, each PTC heating module 3 being transversely inserted into the fin gaps of the evaporator fin area 2 to form its own independent heating zone.

[0057] See Figure 2 Multiple PTC heating modules 3 are arranged in a matrix array in the evaporator fin area 2.

[0058] Several mounting holes are provided on the side plate of the main body 1 of the air cooler, and the PTC heating module 3 is fixedly connected to the mounting holes by bolts.

[0059] See Figure 2 The PTC heating module 3 includes a heating element 33, a set of conductive strips 34 are respectively arranged on both sides of the heating element 33, and a set of insulating film 32 is respectively arranged on the side of the two sets of conductive strips 34 away from the heating element 33. A sleeve 31 is sleeved on the outside of the two sets of insulating film 32.

[0060] See Figure 3 In this embodiment, the electric heating module may include multiple PTC heating modules 3. This embodiment takes nine independent PTC heating modules 3 as an example, in which these nine PTC heating modules 3 are arranged in a matrix of three rows by three columns.

[0061] The sleeve 31 can be made of corrosion-resistant materials such as aluminum alloy or stainless steel to increase its service life and allow it to be immersed in water for heating.

[0062] Existing defrosting devices for air coolers use electric heating for extended periods. Under prolonged high temperature and humidity defrosting conditions, the insulation resistance of the electric heating element is prone to significant attenuation, falling below the minimum limit specified in marine electrical standards, thus failing to meet the insulation safety requirements of marine equipment.

[0063] In this embodiment, the PTC heating module 3 maintains a stable insulation resistance value above the minimum limit specified in marine electrical standards under long-term high temperature and high humidity defrosting conditions, meeting the insulation safety certification requirements of classification societies; moreover, the PTC heating module 3 is easy to install and can be disassembled and replaced at any time.

[0064] The main body 1 of the air cooler is provided with a left side plate and a right side plate. The left side plate and the right side plate are respectively provided with nine sets of mounting holes corresponding to the nine heating zones. The PTC heating module 3 is fixed to the mounting holes by bolts.

[0065] The sensing module includes an attitude sensing unit, a zone temperature sensing unit, an electrical safety monitoring unit, and an auxiliary sensing unit.

[0066] The attitude sensing unit is used to detect the ship's roll and pitch angles in real time.

[0067] Each zone temperature sensing unit is set up for each heating zone and is used to detect the actual temperature of the evaporator fins in each zone.

[0068] The electrical safety monitoring unit is used to monitor the insulation resistance of each PTC heating module 3 online.

[0069] The intelligent controller is electrically connected to the electric heating module and the sensing module respectively. The intelligent controller is configured to receive data from the attitude sensing unit, the zone temperature sensing unit and the electrical safety monitoring unit.

[0070] Based on real-time attitude data and temperature feedback from each zone, a differentiated target temperature is calculated and set for each heating zone according to a preset dynamic thermal field control algorithm.

[0071] Furthermore, the electronic and electrical structures of the attitude sensing unit, the zone temperature sensing unit, and the electrical safety monitoring unit are as follows: The attitude sensing unit uses a dual-axis tilt sensor, which is mounted on the air cooler mounting frame via a vibration-damping bracket. Its X-axis is aligned with the ship's roll axis, and its Y-axis is aligned with the ship's pitch axis. The measurement range is ±30°, and the accuracy is ±0.1°.

[0072] The zoned temperature sensing unit includes nine temperature sensors, which are embedded in the fin roots corresponding to the nine heating zones.

[0073] The electrical safety monitoring unit is integrated into the intelligent controller. It measures insulation resistance using the DC bias method, with a measurement range of 1-100MΩ and an accuracy of ±5%.

[0074] The auxiliary sensing unit includes a humidity sensor and a current sensor. The humidity sensor is installed at the air inlet and air outlet of the evaporator to measure the absolute humidity difference; the current sensor is installed in the fan motor circuit to estimate the air volume change.

[0075] The intelligent controller is a hardware integrated setup. It adopts a multi-channel embedded control system, which specifically includes: a main control unit, a power drive board, an analog input board, and a digital interface board.

[0076] All control loops are completely independent in hardware, and in software, independent tasks are created for each partition through a real-time operating system.

[0077] Based on the above hardware setup, this embodiment further details the control method and operation process of the constant temperature and resistance control system.

[0078] See Figure 4 Step 1: Intelligent defrosting activation judgment.

[0079] The intelligent controller is also configured to perform intelligent defrosting start judgment, which specifically includes estimating the frost thickness and distribution imbalance of each heating zone based on attitude sensor data, zone temperature data, humidity data and wind pressure data.

[0080] The defrost program will be started when any of the following preset defrost start conditions are met: a. The estimated average frost thickness reaches the first thickness threshold.

[0081] b. The distribution imbalance exceeds the imbalance threshold, and the maximum local frost thickness reaches the second thickness threshold.

[0082] The second thickness threshold is greater than the first thickness threshold.

[0083] The intelligent control system performs frost thickness estimation and activation judgment every five minutes.

[0084] First, data acquisition is performed, which involves reading the current attitude data, temperature of each zone, absolute humidity of the incoming and outgoing air, and fan current.

[0085] Secondly, based on the above data, the frost layer thickness is estimated, and a recursive model is used to calculate the frost layer thickness of each zone.

[0086] The formula for calculating the absolute humidity difference is as follows: in, The absolute humidity difference between the inlet and outlet air of the main body 1 of the evaporative cooler. in represents the humidity at the air inlet. "out" refers to the humidity at the air outlet.

[0087] During operation, the deviation of the fan current from the reference current value of the evaporator fins, which is monitored in real time, is used to characterize the change in airflow resistance caused by the thickening of the frost layer. This resistance change information is converted into an airflow influence function and used to correct the calculation results of the frost layer estimation recursive model, so that the frost layer thickness estimate is closer to the actual operating conditions.

[0088] The formula for the air volume influence function is: Where F(Q) is the airflow influence function, Q is the current actual airflow, Qm is the rated airflow, I is the real-time operating current of the evaporative cooler, and Im is the rated current of the evaporative cooler. This is the air volume attenuation coefficient.

[0089] It should be noted that F(Q) is used to directly correct the frost growth model. The smaller F(Q), the worse the ventilation, and the easier it is for condensed water vapor to frost on the fins in the same amount of time. Therefore, the frost growth estimate should be adjusted upward. I is the fan motor operating current measured in real time by a current sensor. When frost on the evaporator causes an increase in duct resistance, the fan load increases, and this current value will rise. Im is the normal operating current of the evaporator motor, which is a pre-calibrated or constant reference value obtained from the nameplate.

[0090] This indicates the squared percentage decrease in airflow caused by a certain increase in current. During the debugging of the intelligent control system, different degrees of frost are simulated, and the actual airflow and current are measured simultaneously. Multiple points are calculated in reverse, and then the average value is taken. The range is usually between 0.1 and 0.3.

[0091] The method for calculating the attitude influence factor is as follows: The attitude influence factor is denoted as Ci. Ci is used to quantify the difference in frost rate in each zone caused by ship tilting. Its calculation requires combining the zone location and ship attitude.

[0092] Among them, the ship's heel angle is θ, with right heel being positive and left heel being negative; the ship's trim angle is φ, with bow heel being positive when pitching and bow heel being negative when sinking.

[0093] See Figure 4 The natural coordinates of each heating zone in the evaporator matrix are (xi, yi), where i represents the heating zone. In this embodiment, for a three-by-three matrix, the range of xi and yi can be from -1 to 1, and i = 1, 2, 3, ... 9.

[0094] The formula for calculating the attitude influence factor Ci is: Where Ci is the attitude influence factor, α is the attitude sensitivity coefficient, and sinθ and sinφ are the sine values ​​of the roll angle and pitch angle, respectively.

[0095] It should be noted that α, calibrated experimentally, is usually greater than 0, and it determines the degree of influence of tilt on the unevenness of frosting. The sine functions of the horizontal tilt angle θ and the vertical tilt angle φ are used because the frosting rate is related to the normal component or residence time of condensate on the fin surface, and is approximately proportional to the sine of the tilt angle.

[0096] In practical applications, when a ship tilts to the right (θ>0), the zone Ci on the right side (xi is positive) increases, indicating that frost forms faster; on the left side (xi is negative), Ci decreases. The same principle applies to trim and heel.

[0097] In the horizontal direction, θ=φ=0 and Ci=1.

[0098] Based on the acquisition or calculation of the above parameters, the formula for calculating the frost layer thickness can be obtained. The formula for calculating the frost layer thickness is as follows: Where, di(k) is the frost thickness of the i-th partition in the current (k-th) estimation cycle, and di(k-1) is the frost thickness of the i-th partition in the previous (k-1) estimation cycle. This is the frosting coefficient. The absolute humidity difference between the inlet and outlet air. To estimate the time interval, Ci is the attitude influence factor of the i-th partition, F(Q) is the air volume influence function, i=1,2,3,…9.

[0099] In this embodiment It lasts for five minutes.

[0100] It is an experimental constant related to the evaporator material, surface properties, and airflow velocity.

[0101] F(Q) reflects the effect of the fan air volume Q on the growth of frost layer; the larger the air volume, the slower the frost layer grows.

[0102] The process for calculating key performance indicators is as follows: Key metrics include average frost thickness, maximum frost thickness, and unevenness.

[0103] The formula for calculating average frost thickness is: in, Let be the average frost thickness of the nine heating zones, and di be the frost thickness of each heating zone. The nine heating zones are sorted from 1 to 9, i = 1, 2, 3, ... 9.

[0104] The formula for calculating the maximum frost thickness is: Among them, dmax is the thickest frost layer in the nine heating zones.

[0105] The formula for calculating the degree of imbalance is: Where U represents the frost unevenness within the nine heating zones, dmax represents the thickest frost layer within the nine heating zones, and dmin represents the thinnest frost layer within the nine heating zones. The average frost thickness across the nine heating zones.

[0106] The threshold determination process is as follows: Preset thresholds: First thickness threshold D1 = 3.0 mm, imbalance threshold U = 0.5, second thickness threshold D2 = 4.0 mm.

[0107] like If condition a is met, then the frost melt is triggered.

[0108] like If condition b is met, the frost melt will be triggered.

[0109] See Figure 5 Step 2: After the defrosting conditions are triggered, prepare for defrosting and perform a safety self-check.

[0110] The intelligent control system starts with a 2-minute delay to avoid frequent start-stop cycles, during which the defrosting conditions are reconfirmed.

[0111] Upon startup, a safety self-test is first performed, and a 250VDC test voltage is applied to all PTC heating modules 3 to measure the insulation resistance.

[0112] If all Ri ≥ 5MΩ, proceed with the normal defrosting procedure; otherwise, implement a graded safety strategy.

[0113] Where Ri is the insulation resistance of each heating zone, i=1,2,3,…9.

[0114] See Figure 4 Step 3: Perform dynamic thermal field control.

[0115] The dynamic thermal field control algorithm is configured to adjust the target temperature of the heating zones at different spatial locations of the evaporator fin area 2 according to the lateral and longitudinal tilt angles.

[0116] In this section, the target temperature is increased for the section located on the side where frost has formed due to the ship's tilt, and decreased for the section located on the opposite side.

[0117] The formula for calculating the target temperature for each zone is as follows:

[0118] Where Tpi is the target defrost temperature set for the i-th heating zone, and Tb is the base defrost temperature. The frost thickness difference compensation coefficient is the estimated frost thickness for the i-th partition. The average frost thickness This is the attitude compensation coefficient.

[0119] It should be noted that β>0 and γ>0, where β signifies a zone with a thicker frost layer, and the zone with a thicker frost layer is di> For each zone, the target temperature is set higher. γ means a zone that frosts faster due to tilt. Zones with Ci>1 frost faster also have their target temperature set higher to accelerate defrosting.

[0120] β represents the number of degrees Celsius that the target defrosting temperature should be increased for every 1 mm that the frost layer thickness exceeds the average value. If β is too small, the compensation effect on the uneven frost layer is weak, which may lead to uneven defrosting. If β is too large, it may cause local overheating, increase energy consumption and potentially reduce the equipment life. During commissioning, it is usually started from the middle value and fine-tuned according to the defrosting uniformity effect. In this embodiment, the value of β is 2.0℃ / mm.

[0121] γ represents the base degree Celsius increase in the target defrosting temperature when the frost rate of the zone increases due to the ship's tilt, i.e., when Ci>1. The range of variation of the attitude influence factor Ci is usually small, so γ needs to be large enough to make the adjustment significant. The value of γ needs to match the maximum tilt angle to ensure that the compensation temperature increment is within a reasonable range when tilted to the maximum. Therefore, in this embodiment, the value of γ is 4.0℃.

[0122] See Figure 5 Step four involves conducting safety monitoring and health management of the intelligent control system during the defrosting process.

[0123] The intelligent controller is also configured to perform health management, which includes: calculating the health index based on the insulation resistance change data of each PTC heating module 3; when the health of a certain group of PTC heating modules 3 is lower than the warning threshold, automatically adjusting the power of its adjacent PTC heating modules 3 for thermal compensation and issuing a maintenance warning.

[0124] The formula for calculating the health index is as follows: Where Ei is the health index of the i-th PTC heating module 3, Ric is the currently measured insulation resistance value of the electric heating, and Rii is the initial insulation resistance reference value of the PTC heating module 3. The rate of change of resistance, The maximum allowable resistance drop rate threshold, , is the weighting coefficient, and log10 is the logarithmic function to the base 10.

[0125] It should be noted that the value of Ei ranges from 0 to 100, and the higher the value, the healthier the person.

[0126] For example =0.7, =0.3 indicates that more emphasis is placed on the absolute value of the current resistance.

[0127] The intelligent controller is configured to enforce a tiered security policy: When the insulation resistance of any PTC heating module 3 is detected to be lower than the first safety threshold but higher than the second safety threshold, the first-level strategy is executed: the heating power of the PTC heating module 3 is reduced and an early warning is issued.

[0128] When the power supply falls below the second safety threshold, the second-level strategy is executed: power to the module is cut off.

[0129] First, the insulation resistance of each PTC heating module 3 in each heating zone is monitored in real time, and the insulation resistance value of each PTC heating module 3 is measured every ten seconds.

[0130] Secondly, a tiered security strategy is activated during the monitoring process.

[0131] Level 1 warning: If 5MΩ>Ri≥2MΩ, limit the power of the PTC heating module 3 to 70%, record the fault code, and trigger a yellow alarm.

[0132] Secondary protection: If Ri < 2MΩ, immediately cut off the power supply to the module, trigger a red alarm, and initiate thermal field reconfiguration.

[0133] Finally, when a PTC heating module 3 fails, the compensation temperature of its adjacent modules is calculated, and the temperature increase of the adjacent PTC heating module 3 is calculated to achieve thermal field reconstruction.

[0134] The formula for calculating the compensation temperature is: in, The compensation temperature for the nth adjacent PTC heating module 3 is given by ∆Tcmax, where ∆Tcmax is the maximum compensation temperature increment, and |∆roml| and |∆col| are the absolute values ​​of the difference in row number and column number between the adjacent module and the failed module.

[0135] It should be noted that, This means that the closer to the failed module, the greater the temperature increase it bears in compensation.

[0136] In practical applications, such as modules that are adjacent vertically or horizontally, The diagonally adjacent ones are 2.

[0137] Step 5: Determine if defrosting is complete.

[0138] The intelligent controller determines that defrosting is complete based on any of the following conditions: a. The actual temperature of all heating zones has reached and stabilized within the preset error band of their respective target temperatures, and has remained stable for a preset period of time.

[0139] b. The total defrosting time reaches the preset maximum safe time.

[0140] The intelligent control system monitors three completion conditions simultaneously, as follows: Main condition (Condition 1): All zone temperatures satisfy |Tmi-Tpi|≤1.0℃ and last for 3 minutes.

[0141] Safety condition (condition 2): Total defrosting time reaches 30 minutes (maximum safe time).

[0142] Inclined optimization condition (condition 3): When θ>10° and lasts for 5 minutes, if the left zone (upwind side) has reached the standard and stabilized for 3 minutes, and the temperature Tmi of the right zone is>2℃, then the defrosting will end early.

[0143] Priority order: Condition 3 > Condition 1 > Condition 2. Heating will stop once any condition is met.

[0144] See Figure 5 Step 6: After each defrost cycle, first record key data, then update the health model, and finally optimize subsequent strategies.

[0145] Key data include defrosting time, final temperature, insulation resistance changes, and energy consumption for each zone.

[0146] The health model is updated based on the recorded data, and the subsequent strategy is optimized by appropriately reducing the maximum power of PTC heating module 3 with poor health during the next defrost and prompting preventive maintenance.

[0147] Example 2, see Figure 4 A control method for a constant temperature and constant resistance control system for defrosting marine air coolers, using the constant temperature and constant resistance control system for defrosting marine air coolers as described above, includes the following steps: S0. Based on the attitude sensing unit data, zone temperature data, humidity data and wind pressure data, estimate the frost thickness and distribution imbalance of each heating zone. When any of the following preset conditions for defrosting are met, it is determined that defrosting needs to be initiated, and the process proceeds to step S1: a. The estimated average frost thickness reaches the first thickness threshold; b. The distribution imbalance exceeds the imbalance threshold, and the maximum local frost thickness reaches the second thickness threshold; S1. The intelligent control system performs intelligent defrosting start judgment. When the start conditions are met, it enters the defrosting program and performs system self-check. S2. The intelligent controller collects the ship's roll angle, pitch angle, and the actual temperature of each heating zone in real time. S3: The intelligent controller calculates the target temperature required for each heating zone based on the dynamic thermal field control algorithm. S4. The intelligent controller adjusts the power of each PTC heating module 3 through an independent control loop so that the actual temperature of each zone reaches its target temperature. S5. During the defrosting process, the insulation resistance is continuously monitored. If the insulation resistance of any heating zone is lower than the first safety threshold, an alarm is triggered as a safety strategy. S6. When any of the following defrosting completion conditions are met, heating will be stopped and defrosting will end: The intelligent controller determines that defrosting is complete based on any of the following conditions: a. The actual temperature of all heating zones has reached and stabilized within the preset error band of their respective target temperatures, and has remained stable for a preset period of time. b. The total defrosting time reaches the preset maximum safe time.

[0148] The tiered security strategy in step S5 includes: When the insulation resistance of any PTC heating module 3 is detected to be lower than the first safety threshold but higher than the second safety threshold, the first-level strategy is executed: reduce the heating power of the PTC heating module 3 and issue an early warning; when it is lower than the second safety threshold, the second-level strategy is executed: cut off the power supply to the module.

[0149] It also includes step S7: recording and analyzing the performance data of each PTC heating module 3 during each defrosting process, updating its health model, and optimizing the power allocation and defrosting start-up strategy for subsequent defrosting cycles based on the health model.

[0150] Obviously, the embodiments described above are merely some, not all, embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

Claims

1. A constant temperature and constant resistance control system for defrosting marine air coolers, characterized in that: include: The main body of the air cooler (1) has an evaporator fin area (2) inside. The electric heating module includes multiple independent PTC heating modules (3), each of which is transversely inserted into the fin gap of the evaporator fin area (2) to form its own independent heating zone; The sensing module includes: An attitude sensing unit is used to detect the ship's roll and pitch angles in real time. A zone temperature sensing unit is provided for each heating zone. The zone temperature sensing unit is used to detect the actual temperature of the evaporator fin area (2) of each zone. An electrical safety monitoring unit is used to monitor the insulation resistance of each PTC heating module (3) online; An intelligent controller is electrically connected to an electric heating module and a sensing module, respectively. The intelligent controller is configured to receive data from an attitude sensing unit, a zone temperature sensing unit, and an electrical safety monitoring unit. Based on real-time attitude data and temperature feedback from each zone, a differentiated target temperature is calculated and set for each heating zone according to a preset dynamic thermal field control algorithm.

2. The constant temperature and resistance control system for defrosting marine air coolers according to claim 1, characterized in that: The sensing module also includes an auxiliary sensing unit, which is used to measure the absolute humidity difference between the air inlet and outlet of the evaporator of the main body of the air cooler (1).

3. The constant temperature and resistance control system for defrosting marine air coolers according to claim 1, characterized in that: Multiple PTC heating modules (3) are arranged in a matrix array in the evaporator fin area (2); The main body (1) of the air cooler has several mounting holes on its side plate, and the PTC heating module (3) is fixedly connected to the mounting holes by bolts. The PTC heating module (3) includes a heating element (33), and a set of conductive strips (34) are respectively provided on both sides of the heating element (33). An insulating film (32) is respectively provided on the side of the two sets of conductive strips (34) away from the heating element (33). A sleeve (31) is provided on the outside of the two sets of insulating films (32).

4. The constant temperature and resistance control system for defrosting marine air coolers according to claim 1, characterized in that: The dynamic thermal field control algorithm is configured to: adjust the target temperature of the heating zones at different spatial positions of the evaporator fin area (2) according to the lateral tilt angle and the longitudinal tilt angle; In this section, the target temperature is increased for the section located on the side where frost has formed due to the ship's tilt, and decreased for the section located on the opposite side.

5. The constant temperature and resistance control system for defrosting marine air coolers according to claim 1, characterized in that: The intelligent controller is also configured to perform intelligent defrosting start judgment, which specifically includes: estimating the frost thickness and distribution imbalance of each heating zone based on the attitude sensing unit data, zone temperature data, humidity data and wind pressure data; The defrost program will be started when any of the following preset defrost start conditions are met: a. The estimated average frost thickness reaches the first thickness threshold; b. The distribution imbalance exceeds the imbalance threshold, and the maximum local frost thickness reaches the second thickness threshold; Wherein, the second thickness threshold is greater than the first thickness threshold.

6. The constant temperature and resistance control system for defrosting marine air coolers according to claim 1, characterized in that: The intelligent controller is also configured to perform health management, which includes: The health index is calculated based on the insulation resistance change data of each PTC heating module (3). When the health of a certain group of PTC heating modules (3) is lower than the warning threshold, the power of its adjacent PTC heating modules (3) is automatically adjusted for thermal compensation, and a maintenance warning is issued. The intelligent controller is also configured to execute a tiered security policy: When the insulation resistance of any PTC heating module (3) is detected to be lower than the first safety threshold but higher than the second safety threshold, the first-level strategy is executed: the heating power of the PTC heating module (3) is reduced and an early warning is issued; When the power supply falls below the second safety threshold, the second-level strategy is executed: power to the module is cut off.

7. The constant temperature and resistance control system for defrosting marine air coolers according to claim 1, characterized in that: The intelligent controller determines that defrosting is complete based on any of the following conditions: a. The actual temperature of all heating zones has reached and stabilized within the preset error band of their respective target temperatures, and has remained stable for a preset period of time. b. The total defrosting time reaches the preset maximum safe time.

8. A control method for a constant temperature and resistance control system for defrosting marine air coolers, using the constant temperature and resistance control system for defrosting marine air coolers as described in any one of claims 1-7, characterized in that: Includes the following steps: S0. Based on the attitude sensing unit data, zone temperature data, humidity data and wind pressure data, estimate the frost thickness and distribution imbalance of each heating zone. When any of the following preset conditions for defrosting are met, it is determined that defrosting needs to be initiated, and the process proceeds to step S1: a. The estimated average frost thickness reaches the first thickness threshold; b. The distribution imbalance exceeds the imbalance threshold, and the maximum local frost thickness reaches the second thickness threshold; S1. The intelligent control system performs intelligent defrosting start judgment. When the start conditions are met, it enters the defrosting program and performs system self-check. S2. The intelligent controller collects the ship's roll angle, pitch angle, and the actual temperature of each heating zone in real time. S3: The intelligent controller calculates the target temperature required for each heating zone based on the dynamic thermal field control algorithm. S4. The intelligent controller adjusts the power of each PTC heating module (3) through an independent control loop so that the actual temperature of each zone reaches its target temperature. S5. During the defrosting process, the insulation resistance of the electric heating is continuously monitored. If the insulation resistance of any heating zone is lower than the first safety threshold, an alarm safety strategy is triggered. S6. When any of the following defrosting completion conditions are met, heating will be stopped and defrosting will end: The intelligent controller determines that defrosting is complete based on any of the following conditions: a. The actual temperature of all heating zones has reached and stabilized within the preset error band of their respective target temperatures, and has remained stable for a preset period of time. b. The total defrosting time reaches the preset maximum safe time.

9. The control method for the constant temperature and constant resistance control system for defrosting marine air coolers according to claim 8, characterized in that: The tiered security strategy in step S5 includes: During the defrosting process, the insulation resistance is continuously monitored. When the insulation resistance of any PTC heating module (3) is lower than the first safety threshold but higher than the second safety threshold, the first-level strategy is executed: the heating power of the PTC heating module (3) is reduced and an early warning is issued; when it is lower than the second safety threshold, the second-level strategy is executed: the power supply of the module is cut off.

10. The control method for the constant temperature and constant resistance control system for defrosting marine air coolers according to claim 8, characterized in that: It also includes step S7: record and analyze the performance data of each PTC heating module (3) during each defrosting process, update its health model, and optimize the power allocation and defrosting start-up strategy for subsequent defrosting cycles based on the health model.

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