15 results about "Logarithmic mean temperature difference" patented technology

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.

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 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 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 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.