22 results about "Logarithmic mean temperature difference" patented technology

The invention provides a control method and system for high-temperature protection of a hydraulic cylinder, and relates to the field of hydraulic cylinders, and the control method specifically comprises the steps that data are collected through temperature sensors arranged in a cylinder body, a piston rod, oil and the environment, and a three-dimensional temperature field model is constructed based on the Fourier heat conduction law; an oil temperature threshold value is set, a graded cooling mechanism is started when the threshold value is exceeded, and cooling heat is calculated according to a Newton cooling formula and a logarithmic average temperature difference method. Fuzzy PI D control is combined with a neural network prediction model, the cooling intensity is dynamically adjusted according to the temperature rising rate and the load state, and the high-temperature risk is pre-judged. The failure of the sensor is processed by a Kalman filtering algorithm, and the cooling system is automatically switched to a standby loop and alarms if the cooling system fails. The system comprises a temperature acquisition module, a control module, a cooling execution module, an alarm module and a remote communication module, and can solve the problems that an existing protection method is poor in passive cooling effect and unreasonable in timing cooling.

The invention discloses a control method for steam condensate waste heat recovery and waste water heating, a control device for steam condensate waste heat recovery and waste water heating, control equipment and a computer readable storage medium. The thermal load and the logarithmic average temperature difference are calculated based on the energy conservation principle, and the needed heat exchange area is calculated through a logarithmic average temperature difference method. A flow combination scheme of the plate heat exchanger is determined according to the heat exchange area and the flow parameters, a steam condensate side adopts a single flow, and a waste water side adopts asymmetric configuration of double flows or multiple flows so as to adapt to the flow difference of the two sides. In addition, a real-time monitoring mechanism is further established, when the total heat transfer coefficient is decreased by more than 10%, a cleaning program is automatically triggered, continuous and stable operation of the system is guaranteed, and efficient utilization of waste heat resources is achieved.

The invention discloses an in-service plate heat exchanger dirt cleaning judgment method and device based on operation data, and the method comprises the steps: obtaining the operation data, collected in a cleaning period and a current operation season, of a plate heat exchanger, and removing abnormal data to form a cleaning period effective data set and a current operation season effective data set; calculating the heat exchange amount and the logarithmic average temperature difference based on the effective data set, and executing steady-state working condition set screening to obtain steady-state working condition sets of the cleaning period and the current operation season; heat exchange thermal resistance is calculated based on the steady-state working condition set, linear fitting is carried out on the heat exchange thermal resistance and the sum of minus 0.8 power of flow of the two sides of the heat exchanger to obtain heat conduction thermal resistance, and the heat conduction thermal resistance in the cleaning period and the heat conduction thermal resistance in the current operation period are compared to calculate dirt thermal resistance in the current operation period; if the ratio of the dirt heat resistance in the current operation season to the heat conduction heat resistance in the cleaning period exceeds a preset threshold value, it is judged that dirt cleaning needs to be conducted on the plate heat exchanger. A method is provided for improving the efficiency of the plate heat exchanger and reducing carbon emission for heat exchange systems in the fields of heat supply, petrochemical engineering and the like.

The present application provides a method, apparatus, electronic device and storage medium for monitoring the performance of an indirect cooling tower. The method includes: obtaining the inlet and outlet air temperatures and the inlet and outlet water temperatures of each fan section in the indirect cooling tower to be measured; determining the heat dissipation of each fan section according to the inlet and outlet water temperatures and the circulating water flow rate; determining the logarithmic mean temperature difference of each fan section according to the inlet and outlet air temperatures and the inlet and outlet water temperatures; determining the heat transfer coefficient of each fan section according to the heat dissipation, logarithmic mean temperature difference and heat transfer area of each fan section; and determining the performance monitoring result of the indirect cooling tower to be measured according to the heat transfer coefficients of each fan section. The method provided by the above solution determines the heat transfer coefficient of each fan section by obtaining the inlet and outlet air temperatures and the inlet and outlet water temperatures of each fan section in the indirect cooling tower to be measured in real time, and further determines the performance monitoring result of the indirect cooling tower to be measured, ensuring that the obtained performance monitoring result conforms to the actual heat dissipation situation of the indirect cooling tower and improving the accuracy of the performance monitoring result of the indirect cooling tower.

This application relates to the field of selection data correction technology, and discloses a method for correcting air conditioner selection data. The method includes obtaining the inlet water temperature, outlet water temperature, and logarithmic mean temperature difference of an air conditioner heat exchanger; determining the corrected evaporation temperature and corrected condensation temperature based on the inlet water temperature, outlet water temperature, and logarithmic mean temperature difference; and determining the corrected air conditioner selection data based on the corrected evaporation temperature and corrected condensation temperature. This method allows for the correction of air conditioner selection data according to the corrected evaporation temperature and corrected condensation temperature, resulting in more accurate air conditioner selection data. Users can refer to the corrected air conditioner selection data for air conditioner selection, effectively improving the accuracy of the air conditioner selection results and reasonably reducing the workload of selection preparation while increasing the efficiency of air conditioner selection. This application also discloses an apparatus and storage medium for correcting air conditioner selection data.

The invention discloses an air conditioner and a calculation method for the heat exchange capacity of the air conditioner. The method comprises the steps that environment parameters of the environment where the air conditioner is located are obtained; when the air conditioner is started to run, heat exchange characteristic parameters of an indoor heat exchanger are obtained; according to the environment parameters and the heat exchange characteristic parameters, the surface heat exchange coefficient, the surface heat exchange area and the heat exchange logarithmic average temperature difference of the indoor heat exchanger are calculated; and on the basis of the convective heat exchange principle, the heat exchange capacity of the indoor heat exchanger is calculated according to the surface heat exchange coefficient, the surface heat exchange area and the heat exchange logarithmic average temperature difference. By the adoption of the means, the air conditioner and the calculation method for the heat exchange capacity of the air conditioner can effectively calculate the heat exchange capacity of the air conditioner through the heat convection principle by means of the original structure of the air conditioner, no sensor needs to be additionally arranged, and the accuracy of the calculation result of the heat exchange capacity can be guaranteed.

The invention relates to the field of refrigerating system design, in particular to a multi-split refrigerating system design method, electronic equipment and a readable storage medium, and the multi-split refrigerating system design method comprises the following steps: S1, building a refrigerating system, and simultaneously driving n refrigerating equipment to operate through a single compressor; s2, supposing that the outlet air temperature of an evaporator of the refrigeration equipment is as follows; s3, calculating the thermal load Q of the refrigeration equipment; s4, calculating the heat exchange coefficient of the evaporator and the logarithmic average temperature difference of the evaporator according to the heat exchange coefficient and the logarithmic average temperature difference assumed in the step S2; s5, the heat exchange area U of the evaporator is determined according to the heat load Q of the refrigeration equipment, the logarithmic average temperature difference of the evaporator and the heat exchange coefficient of the evaporator; and S6, the heat exchange amount Q of the refrigeration equipment is calculated. According to the method, the running number range of the freezing and refrigerating equipment in the multi-split refrigerating system can be determined, and the optimal running number of the freezing and refrigerating equipment under the corresponding demand condition can be determined.

The invention discloses a full-flow-channel zero-bypass concentric sleeve reverse flow type heat exchanger, and belongs to the technical field of heat exchange equipment. According to the heat exchanger, the fluid bypass problem existing in a tubular heat exchanger is fundamentally eliminated, fluid participating in heat exchange completely flows in the closed pipeline in the pure axial direction, two-strand or multi-strand pure countercurrent flow heat exchange can be achieved through reasonable process arrangement, the logarithmic average temperature difference correction coefficient approaches to 1, design is easy and convenient, and calculation is accurate and reliable. The heat exchanger integrates the advantages of a traditional tubular heat exchanger, a plate-fin heat exchanger, a lamella heat exchanger, a plate-type heat exchanger and a double-pipe heat exchanger, overcomes the defects of the traditional tubular heat exchanger, the plate-fin heat exchanger, the lamella heat exchanger, the plate-type heat exchanger and the double-pipe heat exchanger, is suitable for heat exchange of various media and complex working conditions, and can realize micro-channel and large-scale.

The invention discloses a heat transfer performance monitoring method and device, electronic equipment and a storage medium, and relates to the technical field of performance detection.The logarithmic average temperature difference and inlet and outlet air temperature difference are calculated by obtaining the temperature of an air outlet, and a comprehensive heat dissipation coefficient is obtained through a preset calculation formula and serves as a quantitative index of the heat transfer performance of a cooling tower; and real-time online analysis and output are carried out through the industrial personal computer, so that real-time and multi-dimensional quantitative evaluation on the heat transfer performance is realized, and manual regular inspection or single parameter evaluation is not adopted. The technical problems that in the prior art, due to the fact that manual regular inspection or single parameter evaluation is adopted, performance change trend recognition lags behind, the superimposed effect of external pollution and internal scaling cannot be distinguished, and then operation optimization and maintenance decisions of a cooling system are affected can be solved. The technical effects that the performance change trend is accurately recognized in real time, the superimposed effect of external pollution and internal scaling is effectively distinguished, and operation and maintenance decisions of the cooling system are optimized are achieved.

This invention discloses an optimization method for mixed refrigerants in the cryogenic separation of coke oven gas, belonging to the field of chemical process engineering technology. A five-element mixed refrigerant refrigeration simulation model is established for the process of producing LNG and co-producing hydrogen from cryogenic separation of coke oven gas. The molar flow rates of each refrigerant component are used as optimization variables, and minimizing the cyclic compression work is the objective function. Constraints include the minimum temperature difference of the heat exchanger, the logarithmic mean temperature difference, and the refrigerant outlet temperature in the cold box. A genetic algorithm is used to perform a global search on the refrigerant flow composition to obtain an approximate optimal solution. Then, using this solution as the center, a composite method is used to achieve local fine-tuning optimization, ultimately outputting the optimal refrigerant ratio that satisfies the constraints. This invention overcomes the low efficiency problem of traditional empirical manual optimization methods, combining the advantages of global search and local convergence, effectively reducing process energy consumption, and has significant energy-saving and engineering application value.

The utility model discloses an automatic online backwashing system of a plate heat exchanger, and belongs to the technical field of heat supply. The system comprises a first-level network water supply main pipe, a first-level network water return main pipe, a second-level network water supply main pipe, a second-level network water return main pipe, a plate heat exchanger first-level network water supply pipeline, a plate heat exchanger first-level network water return pipeline, a plate heat exchanger second-level network water supply pipeline, a plate heat exchanger second-level network water return pipeline, a plate heat exchanger and a logic control system. The utility model aims to solve the problems that a water flow pulse effect can be realized by utilizing the quick-opening and quick-closing functions of the pulse backwashing device by inputting a large amount of manpower, and the dirt washing effect can be greatly improved by continuously vibrating and impacting high and low pressure. An inlet door and a blow-down door of the plate heat exchanger are changed into electric valves, and pressure difference or logarithmic average temperature difference monitoring is set, so that the dynamic online backwashing function can be realized, the manufacturing cost is low, and the transformation is convenient.

The invention belongs to the technical field of valve control, and particularly relates to a device with a heat exchanger flow resistance diagnosis function and a control method thereof. The valve comprises an actuator, a V-shaped ball valve, a first pressure sensor, a second pressure sensor and a first temperature sensor. The method comprises the steps that input data of an actuator are obtained in real time, the instantaneous flow rate and the Reynolds coefficient are calculated, the real-time flow state is obtained according to the Reynolds coefficient, an attenuation model is established through the resistance coefficient and the logarithmic average temperature difference, an alarm threshold value is set, and early warning is conducted on the scaling critical point of the primary side of the heat exchanger in advance. By means of the actuator with the functions of operation data collection, data analysis and scaling early warning, deep fusion of state monitoring of the valve and the heat exchanger is achieved; different from single pressure difference alarm, the influence of flow fluctuation on the pressure difference is eliminated through a resistance coefficient, the accuracy of scaling judgment is improved in combination with the logarithmic temperature difference LMTD, and'flow resistance + heat transfer 'two-dimensional verification is formed.

The application discloses a kind of in-service plate heat exchanger dirt cleaning judgment method and device based on operating data, comprising: obtaining the operating data of plate heat exchanger collected in cleaning period and current operating season, form cleaning period effective data set and current operating season effective data set after removing abnormal data;Based on effective data set, calculate heat transfer and logarithmic mean temperature difference, execute steady state condition set screening, obtain the steady state condition set of cleaning period and current operating season;Based on steady state condition set, calculate heat transfer resistance, and the sum of the negative 0.8 power of heat transfer resistance and the flow of both sides of heat exchanger is linearly fitted to obtain thermal resistance, compare the thermal resistance of current operating season dirt resistance calculated from cleaning period and current operating season;If the ratio of current operating season dirt resistance and cleaning period thermal resistance exceeds preset threshold, it is judged that plate heat exchanger needs to be cleaned for dirt.The method is provided for improving the efficiency of plate heat exchanger and reducing carbon emission of heat exchange system in heating, petrochemical and other fields.

The present application relates to the technical field of energy saving optimization of industrial circulating water system, and particularly relates to a circulating water system temperature and flow optimization design method, which comprises the following steps: obtaining the reference circulating water total flow, the cooling tower inlet and outlet water temperature and the heat exchanger group hot side inlet and outlet temperature; determining the heat load according to the energy conservation, and establishing the temperature boundary of the cooling tower outlet corresponding to the heat exchanger group cold side inlet, the cooling tower inlet corresponding to the heat exchanger group cold side outlet, and calculating the reference logarithmic mean temperature difference; obtaining the allowable water spray density after the transformation, the design wet bulb temperature and the preset threshold value; taking the reference circulating water total flow as the initial value for iteration, using the approximation degree model to calculate the cooling tower outlet water temperature, combining the heat load to calculate the cooling tower inlet water temperature and calculating the target logarithmic mean temperature difference, updating the flow according to the relative deviation until the threshold value is met, and outputting the target circulating water total flow. The present application can obtain a verifiable matching flow under the constraint condition, reduce the trial operation adjustment cost and inhibit the risk of over-limit.

The invention discloses a fuel cell system heat dissipation capability reduction online diagnosis method, which comprises the following steps: entering a diagnosis window when judging that a fuel cell stack enters a steady state; calculating stack heat production based on the thermal neutral voltage, and calculating heat dissipation values, wherein the heat dissipation values comprise a shell heat dissipation value and a tail gas heat carrying value; subtracting the heat dissipation value from the stack heat production to obtain the heat load of the radiator; calculating a logarithmic average temperature difference, and dividing the heat load of the radiator by the logarithmic average temperature difference to obtain the actual heat transfer capacity of the radiator; calculating the benchmark heat transfer capacity, dividing the actual heat transfer capacity of the radiator by the benchmark heat transfer capacity to obtain a pollution blockage factor, subtracting the pollution blockage factor from 1 to obtain capacity loss, and judging that the heat dissipation capacity is reduced when the pollution blockage factor is smaller than a first value or the capacity loss is larger than a second value, the duration is larger than a third value and the reference residual error of the fan is larger than a fourth value. According to the invention, the problems of poor environmental adaptability, many false alarms and lack of physical modeling of radiator blocking of the fuel cell system are solved.

The invention discloses a soot blowing method, device and equipment for a boiler heating surface and a storage medium, and relates to the technical field of boiler combustion. The method comprises the following steps: calculating the energy loss degree of each boiler heating surface according to a working medium entropy flow parameter, a heat transfer amount, a logarithmic average temperature difference and a flue gas flow characteristic parameter of each boiler heating surface; normalizing the energy loss degree of each boiler heating surface to obtain an energy loss factor of each boiler heating surface; the pollution degree of the corresponding boiler heating surface is calculated based on the energy loss factor of each boiler heating surface and a preset energy loss reference value, and the pollution degree of each boiler heating surface is obtained; and determining a soot blowing strategy of each boiler heating surface based on the pollution degree of each boiler heating surface. According to the technical scheme, the soot blowing accuracy of the heating surface of the boiler is improved.

A method for assessing the condition of air coolers in hydropower units based on relative heat transfer coefficients involves collecting operational data such as the inlet and outlet temperatures of hot and cold fluids and the mass flow rate of the cooling medium. After steady-state screening, outlier filtering, and cold fluid temperature correction, the logarithmic mean temperature difference and cooling capacity Q are calculated to obtain the relative heat transfer coefficient. k ri Sorted by unit model k ri The values ​​are calculated, the top 5 minimum values ​​are extracted, and combined with a preset threshold to determine the air cooler degradation risk. The output includes the unit model number, etc. k ri The method provides an evaluation table of values ​​and corresponding equipment, along with graded maintenance recommendations. It can detect the performance of air coolers even when the heat exchange area is unknown, and compare the performance of different air coolers. This method eliminates area errors by using conventional data, saves costs, and achieves accurate performance evaluation, early warning, and cross-equipment performance comparison.

The application discloses a PCM heat exchanger flow channel type selection optimization method and device, and is implemented according to the following steps: S1, obtaining the logarithmic mean temperature difference of the whole PCM heat exchanger according to the preset plate heat exchanger shape size, import and export air temperature and phase change point temperature of the PCM phase change material, and establishing an energy equation based on the logarithmic mean temperature difference; S2, solving the energy equation by using a numerical iteration method, and obtaining the flow channel design parameters most meeting the conditions by using a difference matrix; S3, obtaining a thermal performance factor according to the flow channel design parameters, repeating the above step S2 for different air flow channel spacings, obtaining multiple groups of air spacing and corresponding PCM heat exchange plate thickness combinations, and obtaining the optimal flow channel design parameters according to a thermal performance factor matrix, in combination with the range limitation of the air spacing and the corresponding PCM heat exchange plate thickness. The application solves the problems of low utilization efficiency of the phase change material and low energy conversion efficiency of the PCM heat exchanger designed by the current design type selection optimization method.

The invention relates to the technical field of model selection data correction, and discloses a method for correcting air conditioner model selection data. The method comprises the steps that the water inlet temperature, the water outlet temperature and the logarithmic average temperature difference of the air conditioner heat exchanger are obtained; according to the water inlet temperature of the air conditioner heat exchanger, the water outlet temperature of the air conditioner heat exchanger and the logarithmic average temperature difference, the corrected evaporation temperature and the corrected condensation temperature are determined; and according to the corrected evaporation temperature and the corrected condensation temperature, corrected air conditioner type selection data are determined. According to the scheme, the air conditioner type selection data can be corrected according to the corrected evaporation temperature and the corrected condensation temperature, so that more accurate air conditioner type selection data can be obtained, a user can refer to the corrected air conditioner type selection data to perform air conditioner type selection, the accuracy of an air conditioner type selection result is effectively improved, and the user experience is improved. The air conditioner model selection efficiency is improved, and meanwhile the model selection preparation workload is reasonably reduced. The invention further discloses a device for correcting the air conditioner type selection data and a storage medium.

The application discloses a kind of fuel cell system heat dissipation capacity decline online diagnosis method, comprising: when judging fuel cell stack enters steady state, enter diagnostic window;Based on heat neutral voltage, calculate the heat production of electric pile, calculate heat dissipation value, the heat dissipation value includes: shell heat dissipation value and exhaust gas heat carrying value;The heat dissipation value is obtained by subtracting the heat production of electric pile from heat dissipation value and obtains radiator heat load;Logarithmic mean temperature difference is calculated, and the actual heat transfer capacity of radiator is obtained by dividing radiator heat load by logarithmic mean temperature difference;Calculate reference heat transfer capacity, and the fouling factor is obtained by dividing the actual heat transfer capacity of radiator by reference heat transfer capacity, and the capacity loss is obtained by subtracting the fouling factor from 1, when the fouling factor is less than the first value or the capacity loss is greater than the second value and the duration is greater than the third value, simultaneously judge fan reference residual is greater than the fourth value, judge heat dissipation capacity decline.The application solves the problems of poor environmental adaptability of fuel cell system, false alarm, lack of physical modeling of radiator obstruction.

The utility model discloses a cross countercurrent heat exchange device suitable for a heat pump unit, and relates to the technical field of enhanced heat transfer. The heat exchange device comprises a flow divider, a flow collector, a heat exchange part, a fan and a shell. The heat exchange part comprises a heat exchange coil and fins; one end of the heat exchange coil pipe is communicated with the flow divider, and the other end of the heat exchange coil pipe is connected with the flow collector; the fins are arranged on the heat exchange coil pipe in a sleeving mode in the direction perpendicular to the heat exchange coil pipe. The shell covers the outer side of the flow divider, the outer side of the flow collector, the outer side of the heat exchange coil pipe, the outer side of the fin and the outer side of the draught fan, ventilation holes are further formed in the shell, and the ventilation holes and the draught fan are oppositely arranged. According to the utility model, the logarithmic average temperature difference between air and a refrigerant can be increased, so that the heat exchange efficiency of a unit is improved.