A combined cooling and power system and an optimization method, device, medium and product thereof

Abstract

The application discloses a combined cooling heating and power system and an optimization method, equipment, medium and product thereof, relates to the field of low-temperature waste heat recovery, and the optimization method comprises the following steps: acquiring a waste heat temperature to be recovered, combining a working medium critical temperature and a working medium heat capacity of a preselected working medium, determining an optimal working medium of an organic Rankine cycle subsystem of the combined cooling heating and power system by using a working medium screening model; according to the waste heat temperature to be recovered, establishing an optimization model with a maximum exergy efficiency, a maximum return on investment and a maximum carbon dioxide emission reduction as objective functions and with a preset range of decision variables as constraint conditions; and solving the optimization model by using a non-dominated sorting genetic algorithm to obtain optimal decision variables, so that the combined cooling heating and power system recovers the waste heat to be recovered based on the optimal working medium and the optimal decision variables. The application improves the waste heat recovery efficiency of the CCHP system.

Description

Technical Field

[0001] This application relates to the field of low-temperature waste heat recovery, and in particular to a combined cooling, heating and power system and its optimization methods, equipment, media and products. Background Technology

[0002] With the intensification of global climate change, energy transformation has become a pressing global issue. How to effectively utilize renewable energy and improve energy efficiency, especially in the field of waste heat recovery, has become an important research direction in recent years. In the area of ​​low-temperature waste heat recovery, combined cooling, heating, and power (CCHP) systems have received widespread attention due to their advantages in integrating electricity, heating, and cooling. However, in practical applications, the design of low-temperature waste heat recovery systems still faces a series of challenges, particularly in the selection of the working fluid, which is one of the key factors affecting the overall thermal efficiency and economic viability of the system.

[0003] Low-temperature waste heat, as a renewable energy source, has long been underutilized due to its low temperature and limited energy density. However, with the continuous development of energy recovery technologies, the utilization of low-temperature waste heat is gradually gaining attention. Traditional heat recovery systems typically rely on direct heat transfer and heat exchange methods, which are often inefficient in recovering low-temperature waste heat. Against this backdrop, combined heat and power (CHP) systems have emerged, capable of simultaneously providing heat and electricity, improving energy recovery efficiency while reducing greenhouse gas emissions. CCHP systems are developed based on this, further enhancing the overall efficiency of the system by adding refrigeration modules.

[0004] The Organic Rankine Cycle (ORC), as a relatively mature low-temperature heat recovery technology, has significant advantages in utilizing low-temperature waste heat. ORC systems use organic working fluids, achieving heat conversion and recovery at relatively low temperatures, resulting in high energy conversion efficiency. Compared to traditional steam Rankine cycle systems, ORC systems have a lower operating temperature range, making them suitable for low-temperature heat sources including industrial waste heat, geothermal energy, and solar energy. In recent years, research on ORC systems has increasingly focused on working fluid selection, thermodynamic performance optimization, system design, and economic analysis. The choice of different working fluids directly affects the system's efficiency and economy; therefore, working fluid selection has become an important research direction.

[0005] In ORC systems, the choice of working fluid has a crucial impact on system performance. An ideal working fluid should possess characteristics such as a low boiling point, a large expansion ratio, high thermal conductivity, and low environmental impact. Traditional ORC systems commonly use working fluids including Freon-based compounds, ammonia, and R245fa, but these fluids have limitations in terms of environmental impact, particularly their high GWP (Global Warming Potential) and ODP (Ozone Depletion Potential), which no longer meet modern environmental protection requirements. Therefore, in recent years, many scholars have begun to explore the use of green working fluids with low GWP and low ODP. In addition, the thermophysical properties of the working fluid, such as critical temperature, critical pressure, and thermal conductivity, also directly affect the system's thermal efficiency and reliability.

[0006] To address the working fluid selection problem, researchers have proposed various methods, including optimization models based on thermodynamic analysis and fluid selection methods based on multi-objective optimization. For example, a two-layer multi-objective optimization framework considers working fluid screening and system design at different temperatures, ultimately selecting R152a as the optimal fluid. For ORC systems at specific temperatures, the performance of different working fluids under different objectives was analyzed, concluding that R1234ze(E) fluid possesses the best thermodynamic properties. In these studies, working fluid screening focuses more on optimizing the system's thermal efficiency and economy; however, in practical applications, factors such as the environmental friendliness and sustainability of the working fluid are equally important.

[0007] The optimal design of CCHP systems requires consideration not only of thermodynamic performance but also a comprehensive assessment of their environmental impact and economic benefits. Multi-objective optimization methods have emerged as an important means to improve the overall performance of CCHP systems. By employing multi-objective optimization methods such as Genetic Algorithm (GA), Particle Swarm Optimization (PSO), and simulated annealing, researchers can find an optimal compromise solution among multiple conflicting objectives.

[0008] For example, using the annual cost saving rate and primary energy saving rate as objective functions, the non-dominated sorting genetic algorithm-II was employed to optimize the CCHP system. The results showed a significant improvement in system energy efficiency and energy saving. Particle swarm optimization was used to optimize the energy efficiency, power, and cooling cost of the CCHP system, achieving good economic benefits and energy efficiency ratios. These studies demonstrate that multi-objective optimization methods show promise in improving the performance of CCHP systems and reducing operating costs.

[0009] However, existing multi-objective optimization methods still have certain limitations. When facing high-dimensional problems, existing optimization algorithms are prone to getting trapped in local optima, preventing the optimization results from reaching the global optimum and thus affecting the flexibility and adaptability of the system. Therefore, in the multi-objective optimization of the CCHP system, how to improve the global search capability and computational efficiency of the algorithm remains an urgent problem to be solved.

[0010] Despite significant progress in cryogenic waste heat recovery and CCHP system optimization, some shortcomings remain. First, while working fluid selection has yielded some results, a systematic study of the thermodynamic properties of different fluids under various operating conditions is still lacking, particularly in cryogenic waste heat recovery and fluid selection for special applications. Second, CCHP systems are highly complex in practical applications, involving the optimization of multiple devices and objectives. Therefore, existing optimization algorithms and models still have limitations, failing to fully consider the interactions between various components within the system. Furthermore, existing research largely focuses on the thermodynamic performance and economic analysis of the system, neglecting potential safety and environmental impacts during actual operation. Therefore, future research should emphasize the comprehensive design of cryogenic waste heat recovery systems, especially in working fluid selection, equipment configuration, and operational safety, to further improve the system's adaptability and flexibility.

[0011] Low-temperature waste heat recovery systems, especially combined cooling, heating, and power (CCHP) systems incorporating ORC technology, have become an important way to improve energy efficiency and reduce carbon emissions. However, the performance of these systems is limited by many factors, and the selection of the working fluid and system optimization remain research hotspots and challenges. Future research should further delve into the design of low-temperature waste heat recovery systems, explore more efficient and environmentally friendly working fluids, and adopt more comprehensive and precise optimization methods to improve the overall performance and economic benefits of CCHP systems. Summary of the Invention

[0012] The purpose of this application is to provide a combined cooling, heating and power system and its optimization method, equipment, medium and product to improve the efficiency of low-temperature waste heat recovery.

[0013] To achieve the above objectives, this application provides the following solution: In a first aspect, this application provides a combined cooling, heating and power system, including: an organic Rankine cycle subsystem, an absorption refrigeration cycle subsystem and a heat pump cycle subsystem; The organic Rankine cycle subsystem includes a first evaporator, a steam turbine, a first intermediate heat exchanger, a second intermediate heat exchanger, a first condenser, and a first pump. The waste heat to be recovered enters from the first inlet of the first evaporator; the first outlet of the first evaporator is connected to the steam turbine; the steam turbine is connected to the first inlet of the first intermediate heat exchanger; the first outlet of the first intermediate heat exchanger is connected to the first inlet of the first condenser; the first outlet of the first condenser is connected to the inlet of the first pump; the outlet of the first pump is connected to the second inlet of the first intermediate heat exchanger; the second outlet of the first intermediate heat exchanger is connected to the first inlet of the second intermediate heat exchanger; and the first outlet of the second intermediate heat exchanger is connected to the second inlet of the first evaporator. The absorption refrigeration cycle subsystem includes a steam generator, a gas-liquid separator, a second condenser, a first pressure reducing valve, a second evaporator, an absorber, and a second pump. The first inlet of the steam generator is connected to the second outlet of the first evaporator; the first outlet of the steam generator is connected to the inlet of the gas-liquid separator; the first outlet of the gas-liquid separator is connected to the second inlet of the second intermediate heat exchanger; the second outlet of the second intermediate heat exchanger is connected to the first inlet of the second condenser; the first outlet of the second condenser is connected to one end of the first pressure reducing valve; the other end of the first pressure reducing valve is connected to the first inlet of the second evaporator; the first outlet of the second evaporator is connected to the first inlet of the absorber; the first outlet of the absorber is connected to the inlet of the second pump; and the outlet of the second pump is connected to the second inlet of the steam generator. The heat pump cycle subsystem includes a third intermediate heat exchanger, a compressor, a third condenser, a second pressure reducing valve, and a third pressure reducing valve. The first inlet of the third intermediate heat exchanger is connected to the second outlet of the gas-liquid separator. The first outlet of the third intermediate heat exchanger is connected to one end of the compressor. The other end of the compressor is connected to the first inlet of the third condenser. The first outlet of the third condenser is connected to one end of the third pressure reducing valve. The other end of the third pressure reducing valve is connected to the second inlet of the third intermediate heat exchanger. The second outlet of the third intermediate heat exchanger is connected to one end of the second pressure reducing valve. The other end of the second pressure reducing valve is connected to the second inlet of the absorber.

[0014] Secondly, this application provides an optimization method for a combined cooling, heating and power (CCHP) system, including: Obtain the temperature of the waste heat to be recovered; Based on the temperature of the waste heat to be recovered, the critical temperature of the pre-selected working fluid, and the heat capacity of the working fluid, the optimal working fluid for the organic Rankine cycle subsystem of the above-mentioned cogeneration system is determined using a working fluid screening model. Based on the temperature of the waste heat to be recovered, an optimization model for the combined cooling, heating and power system is established. The optimization model takes maximizing efficiency, maximizing return on investment, and maximizing carbon dioxide emission reduction as objective functions, and uses the preset range of decision variables as constraints. The decision variables include the outlet pressure of the second pump, the heat exchange temperature difference of the steam generator, and the outlet pressure of the compressor. The optimization model is solved using a non-dominated sorting genetic algorithm to obtain the optimal decision variables, so that the combined cooling, heating and power system can recover the waste heat to be recovered based on the optimal working fluid and the optimal decision variables.

[0015] Optionally, the preselected working fluid includes R1234ze(Z), R1233zd(E), 2-methylpentane, benzene, propyne, dimethyl ether, 1-chloro-3,3,3-trifluoro-1-propene, pentafluoropropane, cyclohexane, toluene, perfluorinated, 1-chloro-3,3,3-trifluoro-1-propene, dimethyl carbonate, 1,1,1,3,3-pentafluorobutane, neopentane, isobutane, isobutene, propane, butene, heptane, hexane, and 1-octane.

[0016] Optionally, based on the temperature of the waste heat to be recovered, the critical temperature of the pre-selected working fluid, and the working fluid's heat capacity, an optimal working fluid is determined using a working fluid screening model, specifically including: Based on the temperature of the waste heat to be recovered, the critical temperature of the pre-selected working fluid, and the heat capacity of the working fluid, the comprehensive score of each pre-selected working fluid is determined using a working fluid screening model. The pre-selected working fluid with the highest comprehensive score is selected as the optimal working fluid.

[0017] Optionally, the working fluid screening model is: ; Where y is the overall score of the pre-selected working fluid; The critical temperature of the working fluid; The temperature of the waste heat to be recovered; The heat capacity of the working fluid.

[0018] Optionally, the objective function is: ; ; ; in, For efficiency; The flow rate of the export logistics of the unit module; The flow rate of imported logistics for unit modules; This refers to the heat loss caused by heat exchange; Total output power; Total energy consumption; ROI is the return on investment. For equipment investment costs; Operating costs; The economic benefits generated; CER represents carbon dioxide emission reduction; The carbon dioxide conversion coefficient; Annual operation time; This is the equivalent output power.

[0019] Optionally, the working fluid of the absorption refrigeration cycle subsystem in the cogeneration system is LiBr·H2O; the working fluid of the heat pump cycle subsystem in the cogeneration system is R1233zd(E).

[0020] Thirdly, this application provides a computer device, including: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the optimization method for a combined cooling, heating and power system as described above.

[0021] Fourthly, this application provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the optimization method for the combined cooling, heating and power system described in any one of the above descriptions.

[0022] Fifthly, this application provides a computer program product, including a computer program that, when executed by a processor, implements the optimization method for the combined cooling, heating and power system described in any one of the above descriptions.

[0023] According to the specific embodiments provided in this application, this application has the following technical effects: This application provides a combined cooling, heating, and power (CCHP) system and its optimization method, equipment, medium, and product. The CCHP system includes an organic Rankine cycle subsystem, an absorption refrigeration cycle subsystem, and a heat pump cycle subsystem. The process involves: obtaining the temperature of the waste heat to be recovered; determining the optimal working fluid for the organic Rankine cycle subsystem using a working fluid screening model based on the waste heat temperature, the critical temperature of the pre-selected working fluid, and the working fluid's heat capacity; establishing an optimization model for the CCHP system based on the waste heat temperature; using the objective functions of maximizing efficiency, maximizing return on investment, and maximizing carbon dioxide emission reduction, with predetermined ranges for decision variables as constraints; and solving the optimization model using a non-dominated sorting genetic algorithm to obtain the optimal decision variables, enabling the CCHP system to recover the waste heat based on the optimal working fluid and optimal decision variables. This application starts with the critical temperature, heat capacity, and waste heat temperature of the working fluid, regresses and establishes a working fluid selection model applicable to the ORC system, determines the optimal working fluid, conducts a comprehensive safety, economic and environmental analysis of the constructed CCHP system, performs multi-objective optimization from the perspectives of safety, economy and environment, obtains the optimal decision variables, thereby improving the efficiency of waste heat recovery in the CCHP system. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 A schematic diagram of a combined cooling, heating and power system provided in an embodiment of this application; Figure 2 Flowchart of optimization method for combined cooling, heating and power system; Figure 3 A schematic diagram illustrating the Pareto front results for multi-objective optimization; Figure 4 This is a schematic diagram of the structure of a computer device provided in an embodiment of this application. Detailed Implementation

[0026] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0027] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0028] In one exemplary embodiment, such as Figure 1 As shown, a combined cooling, heating, and power (CCHP) system is provided, comprising: an organic Rankine cycle subsystem, an absorption refrigeration cycle subsystem, and a heat pump cycle subsystem. Wherein CW represents cooling water, and CWR represents cooling water return water.

[0029] The organic Rankine cycle subsystem includes a first evaporator EVA1, a steam turbine TUR, a first intermediate heat exchanger HEATX1, a second intermediate heat exchanger HEATX2, a first condenser CON1, and a first pump PUMP1; the waste heat to be recovered originates from the first inlet of the first evaporator EVA1 (i.e., Figure 1 The heat source input is connected to the first outlet of the first evaporator EVA1; the first outlet of the steam turbine TUR is connected to the first inlet of the first intermediate heat exchanger HEATX1; the first outlet of the first intermediate heat exchanger HEATX1 is connected to the first inlet of the first condenser CON1; the first outlet of the first condenser CON1 is connected to the inlet of the first pump PUMP1; the outlet of the first pump PUMP1 is connected to the second inlet of the first intermediate heat exchanger; the second outlet of the first intermediate heat exchanger HEATX1 is connected to the first inlet of the second intermediate heat exchanger HEATX2; and the first outlet of the second intermediate heat exchanger HEATX2 is connected to the second inlet of the first evaporator EVA1.

[0030] The absorption refrigeration cycle subsystem includes a steam generator (GEN), a gas-liquid separator (SEP), a second condenser (CON2), a first pressure reducing valve (VALUE1), a second evaporator (EVA2), an absorber (ABS), and a second pump (PUMP2). The first inlet of the steam generator (GEN) is connected to the second outlet of the first evaporator (EVA1). The first outlet of the steam generator (GEN) is connected to the inlet of the gas-liquid separator (SEP). The first outlet of the gas-liquid separator (SEP) is connected to the second inlet of the second intermediate heat exchanger (HEATX2). The second outlet of the second intermediate heat exchanger (HEATX2) is connected to the first inlet of the second condenser (CON2). The first outlet of the second condenser (CON2) is connected to one end of the first pressure reducing valve (VALUE1). The other end of the first pressure reducing valve (VALUE1) is connected to the first inlet of the second evaporator (EVA2). The first outlet of the second evaporator (EVA2) is connected to the first inlet of the absorber (ABS). The first outlet of the absorber (ABS) is connected to the inlet of the second pump (PUMP2). The outlet of the second pump (PUMP2) is connected to the second inlet of the steam generator (GEN).

[0031] The heat pump cycle subsystem includes a third intermediate heat exchanger HEATX3, a compressor COM, a third condenser CON3, a second pressure reducing valve VALUE2, and a third pressure reducing valve VALUE3. The first inlet of the third intermediate heat exchanger HEATX3 is connected to the second outlet of the gas-liquid separator SEP. The first outlet of the third intermediate heat exchanger HEATX3 is connected to one end of the compressor COM. The other end of the compressor COM is connected to the first inlet of the third condenser CON3. The first outlet of the third condenser CON3 is connected to one end of the third pressure reducing valve VALUE3. The other end of the third pressure reducing valve VALUE3 is connected to the second inlet of the third intermediate heat exchanger HEATX3. The second outlet of the third intermediate heat exchanger HEATX3 is connected to one end of the second pressure reducing valve VALUE2. The other end of the second pressure reducing valve VALUE2 is connected to the second inlet of the absorber ABS.

[0032] This application develops a CCHP system, such as Figure 1As shown, the system consists of three subsystems: ORC (Absorption Refrigeration Cycle), ARC (Absorption Refrigeration Cycle), and HPC (Heat Pump Cycle), achieving cascaded energy utilization. Waste heat first enters the first evaporator EVA1 to heat the working fluid of the ORC system. After being heated to a gaseous state, the working fluid drives the turbine TUR to generate electricity. Since the working fluid at the turbine TUR outlet needs to be condensed by cooling water, and the working fluid entering the first evaporator EVA1 needs to be heated, a first intermediate heat exchanger HEATX1 is added for heat exchange, saving on utility cooling water consumption and improving waste heat utilization efficiency. Then, the heat-exchanged working fluid enters the first condenser CON1 for complete condensation. After being pressurized by the first pump PUMP1, it passes through the first intermediate heat exchanger HRATX1 and the second intermediate heat exchanger HEATX2 for waste heat before entering the evaporator for complete vaporization.

[0033] Waste heat, after passing through the ORC system, enters the steam generator GEN of the ARC system to heat the lithium bromide aqueous solution. The gas phase, separated by the gas-liquid separator SEP, first passes through the second intermediate heat exchanger HEATX2 to heat the working fluid of the ORC system, then enters the second condenser CON2 for condensation. After being depressurized by the first pressure reducing valve VALUE1, it enters the second evaporator EVA2 to produce chilled water. The liquid phase stream from the gas-liquid separator SEP is used to heat the working fluid of the HPC system. After being depressurized by the second pressure reducing valve VALUE2, it enters the absorber ABS together with the working fluid from the outlet of the second condenser EVA2 for condensation. After being pressurized by the second pump PUMP2, it returns to the steam generator GEN and is output from the second outlet (Heat source out) of the steam generator GEN. In the HPC system, the working fluid is vaporized in the third intermediate heat exchanger HEATX3 and then enters the compressor COM for upgrading before entering the third condenser CON3, where it outputs high-grade heat. After being depressurized by the third pressure reducing valve VALUE3, it returns to the third intermediate heat exchanger HEATX3. Thus, the CCHP system completes the process of producing high-grade cold energy, heat energy, and electrical energy from low-temperature waste heat.

[0034] In one embodiment, such as Figure 2 As shown, this application provides an optimization method for a combined cooling, heating and power (CCHP) system, comprising: S1: Obtain the temperature of the waste heat to be recovered.

[0035] S2: Based on the temperature of the waste heat to be recovered, the critical temperature of the pre-selected working fluid, and the working fluid heat capacity, the optimal working fluid for the organic Rankine cycle subsystem of the cogeneration system is determined using a working fluid screening model.

[0036] As an optional implementation, the preselected working fluid includes R1234ze(Z), R1233zd(E), 2-methylpentane, benzene, propyne, dimethyl ether, 1-chloro-3,3,3-trifluoro-1-propene (R1132(E)), pentafluoropropane (R270), cyclohexane, toluene, perfluoro(methylcyclohexane) (Novec649), 1-chloro-3,3,3-trifluoro-1-propene (R1132(Z)), dimethyl carbonate (DMC), 1,1,1,3,3-pentafluorobutane (R245FA), neopentane, isobutane (R600a), isobutene, propane (R601a, R600), butene, heptane, hexane, and 1-octane.

[0037] As an optional implementation, S2 specifically includes: S21: Based on the temperature of the waste heat to be recovered, the critical temperature of the pre-selected working fluid, and the heat capacity of the working fluid, the comprehensive score of each pre-selected working fluid is determined using the working fluid screening model.

[0038] The working fluid screening model is as follows: .

[0039] Where y is the overall score of the pre-selected working fluid; The critical temperature of the working fluid; The temperature of the waste heat to be recovered; The heat capacity of the working fluid.

[0040] S22: The pre-selected working fluid with the highest comprehensive score is selected as the optimal working fluid.

[0041] In practical applications, a working fluid screening model is constructed to select the optimal working fluid.

[0042] The ORC system working fluid selection method provided in this application includes: constructing an ORC process flow model using Aspen Plus; selecting 24 pre-selected working fluids covering both environmentally friendly and conventional types; obtaining working fluid thermophysical property data from NIST REFPROP 10.0; developing a working fluid selection program using Python to automatically call Aspen Plus to calculate and search for optimal parameters; calculating the ORC power generation efficiency of the working fluid at different heat source temperatures, analyzing the influence of physical properties and considering environmental safety; and selecting the optimal working fluid. The properties of the pre-selected working fluids are shown in Table 1.

[0043] Table 1 Basic physical properties of the working fluids to be selected

[0044] In this embodiment, seven different waste heat temperatures of 150℃, 140℃, 130℃, 120℃, 110℃, 100℃, and 90℃ were selected within the low-temperature range for study. The cycle thermal efficiency was selected as the objective function, as shown in formula (1), and the pressure of the pump and expander (turbine) were used as manipulated variables to find the optimal operating parameters.

[0045] (1) in, For cycle thermal efficiency; To provide power output for the steam turbine; The pump consumes power; This refers to the heat load of the evaporator.

[0046] To ensure the stable operation of the ORC system, the following restrictions are now added: To ensure that the working fluid can be condensed by the cooling water, the expander outlet temperature is set higher than the cooling water outlet temperature, i.e.: (2) in, This refers to the expander outlet temperature.

[0047] Since we are discussing a subcritical ORC system, we set the working fluid pump pressure to be less than the subcritical pressure, i.e.: (3) in, The pressure of the working fluid pump; This is the critical pressure of the working fluid.

[0048] To prevent damage to the expander and extend its service life, the outlet stream is designed to be free of liquid phase, and the inlet pressure is lower than the saturated vapor pressure of the working fluid at the evaporation temperature, i.e.: (4) in, This represents the gas phase fraction at the turbine outlet. This refers to the inlet pressure of the evaporator. The saturated vapor pressure of the working fluid at the evaporation temperature.

[0049] To ensure that the steam at the expander outlet does not overheat and can be successfully condensed, the outlet pressure is set to be greater than the saturated vapor pressure of the working fluid at 40°C, i.e.: (5) in, This refers to the expander outlet pressure. It is the saturated vapor pressure of the working fluid at 40℃.

[0050] This embodiment considers key factors such as greenhouse gas potential (GWP), ozone depletion potential (ODP), and working fluid safety. To balance thermal efficiency, environmental impact, and safety, the TOPSIS (Technique for Order Preference by Similarity to Ideal Solution) method was used to quantitatively analyze different working fluids, thereby selecting the optimal working fluid. The working fluid with the highest overall score in the ORC system is 1-chloro-3,3,3-trifluoropropene (R1233zd(E)), therefore R1233zd(E) is selected as the working fluid for the ORC system. In this embodiment, LiBr·H2O is used as the working fluid in the ARC system, and R1233zd(E) is used as the working fluid in the HPC system.

[0051] Furthermore, to explore the relationship between the working fluid's thermal efficiency and its key thermodynamic properties in depth, this embodiment incorporates variables such as the working fluid's critical temperature, working fluid heat capacity, and heat source temperature (residual heat temperature) for regression analysis. The working fluid selection model is shown in formula (6): (6) in, The critical temperature (K) of the working fluid. The waste heat temperature (K) The heat capacity of the working fluid is cal / (mol·K)

[0052] The coefficient of determination of the regression model (working fluid selection model) is 0.9604, indicating that the model can accurately reflect the relationship between these variables and cycle thermal efficiency, thus providing a more accurate theoretical basis for the selection of working fluid.

[0053] S3: Based on the temperature of the waste heat to be recovered, establish an optimization model for the combined cooling, heating and power system; the optimization model takes maximizing efficiency, maximizing return on investment and maximizing carbon dioxide emission reduction as objective functions, and uses the preset range of decision variables as constraints; the decision variables include the outlet pressure of the second pump, the heat exchange temperature difference of the steam generator and the outlet pressure of the compressor.

[0054] As an optional implementation, the objective function is: (7) (8) (9) in, For efficiency; The flow rate of the export logistics of the unit module; The flow rate of imported logistics for unit modules; This refers to the heat loss caused by heat exchange; Total output power; Total energy consumption; ROI is the return on investment. For equipment investment costs; Operating costs; The economic benefits generated; CER represents carbon dioxide emission reduction; The carbon dioxide conversion coefficient; Annual operation time; This is the equivalent output power.

[0055] In practical applications, based on the results obtained from the above working fluid screening mechanism model, a CCHP system was developed, such as... Figure 1 As shown.

[0056] S4: The optimization model is solved using a non-dominated sorting genetic algorithm to obtain the optimal decision variables, so that the cogeneration system can recover the waste heat to be recovered based on the optimal working fluid and the optimal decision variables. The working fluid of the absorption refrigeration cycle subsystem in the cogeneration system is LiBr·H2O; the working fluid of the heat pump cycle subsystem in the cogeneration system is R1233zd(E).

[0057] In practical applications, this embodiment uses waste heat at 145℃ as the system heat source. The system can also recover low-temperature waste heat at other temperatures, but adjustments to the system operating parameters (decision variables) are required. To ensure the CCHP system operates under optimal operating parameters, a comprehensive evaluation of system performance is conducted with the objectives of maximizing efficiency, maximizing return on investment, and maximizing carbon dioxide emission reduction. The result R1233ZD(E) from the above working fluid screening model is selected as the working fluid for both the ORC and HPC subsystems. The PUMP2 outlet pressure, GEN heat exchange temperature difference, and COM outlet pressure are selected as decision variables for multi-objective optimization of the CCHP system. The objective function calculation method is shown below: The efficiency of a CCHP system can be expressed as: (10) The calculation methods for different modules are shown in Table 2.

[0058] Table 2 Statistical Table of Analysis Methods for Each Module

[0059] Return on Investment (ROI) is used to assess whether an investment is worthwhile. A higher ROI indicates a more efficient investment, and can be expressed as: (11) in, For the resulting economic benefits ($), Annual operating costs ($), Equipment investment costs ($).

[0060] CO2 production has always been a major contributor to greenhouse gas emissions. Minimizing CO2 emissions by recovering low-temperature waste heat to generate high-grade energy is one of the key indicators for evaluating CCHP (Clean-Consumer Heat Recovery) systems. This embodiment uses annual CO2 reduction for evaluation, which can be expressed as... (12) in, The annual carbon dioxide emission reduction (t) =0.000849t / kWh.

[0061] To ensure technical and economic feasibility, a set of constraints (i.e., the corresponding set ranges for each decision variable) were imposed on the decision variables during the optimization process. The optimization employed a non-dominated sorting genetic algorithm, with specific parameter settings shown in Table 3: a population size of 500 and 500 generations. This optimization method yields the Pareto front, a combination of Pareto optimal solutions. A Pareto optimal solution is a solution among multiple objective functions that cannot be found by simultaneously improving all objectives. The results are as follows... Figure 3 As shown.

[0062] Table 3 Genetic Algorithm Parameter Settings

[0063] To further select the optimal operating point of the system, the entropy weight method is used to calculate the weights of each objective function. The advantage of the entropy weight method is that it can objectively determine the weights based on the data itself, avoiding the subjective bias that may arise from manually setting weights. Subsequently, the TOPSIS method is used to comprehensively evaluate the Pareto front, from which the optimal solution is selected, such as... Figure 3 As shown at point C, point A maximizes both ROI and CER, but its η ex The lowest. Point B has the maximum η. ex However, its ROI and CER are the lowest. Point D is the ideal point, simultaneously satisfying the optimal solution of the three objective functions. Point C is the optimal operating point selected by TOPSIS, maximizing emission reduction benefits and return on investment while ensuring the system meets high performance requirements; Pareto front; Optimal operating point. This method effectively takes into account the relative importance of each optimization objective, providing a more scientific decision-making basis for system design and operation. When the decision variable P... PUMP1 P TUR TGEN The optimal operating state of CCHP was obtained at 14.37 kPa, 9.0 bar, and 5.2 K, respectively, with η E The CER and ROI were 0.80, 1958 t / year, and 0.5377, respectively. Compared with the original design, the CCHP system efficiency increased from 0.78 to 0.80, and the ROI increased from 0.4990 to 0.5377, an increase of approximately 7.8%. The CER increased to 1958 t / year, an increase of approximately 6.4%, indicating that the optimized design effectively reduced the initial investment cost through equipment selection and process improvement, bringing higher returns to investors.

[0064] This application, starting from the critical temperature, heat capacity, and waste heat temperature of the working fluid, regresses and establishes a working fluid selection model applicable to ORC systems, with a determination coefficient of 0.9604, providing scientific guidance for system design and optimization under similar heat source conditions. Furthermore, a comprehensive safety, economic, and environmental analysis was conducted on the constructed CCHP system, quantifying its operating characteristics and optimization potential. Multi-objective optimization was performed on the proposed system from safety, economic, and environmental perspectives. The system offers a rapid return on investment, reducing initial investment and operating costs, shortening the payback period, and lowering energy procurement costs through energy conservation. It also reduces greenhouse gas emissions, promoting sustainable development and environmental protection. The system is suitable for various scenarios, including industrial, commercial, and residential applications, and possesses good system stability and flexibility.

[0065] In one exemplary embodiment, a computer device is provided, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the above-described optimization method for a combined cooling, heating and power system.

[0066] In one exemplary embodiment, a computer-readable storage medium is provided storing a computer program that, when executed by a processor, implements the above-described optimization method for a combined cooling, heating, and power system.

[0067] In one exemplary embodiment, a computer program product is provided, including a computer program that, when executed by a processor, implements the above-described optimization method for a combined cooling, heating, and power system.

[0068] In one exemplary embodiment, a computer device is provided, which may be a server or a terminal, and its internal structure diagram may be as follows. Figure 4As shown, this computer device includes a processor, memory, input / output (I / O) interfaces, and a communication interface. The processor, memory, and I / O interfaces are connected via a system bus, and the communication interface is also connected to the system bus via the I / O interfaces. The processor provides computational and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system, computer programs, and databases. The internal memory provides the environment for the operating system and computer programs stored in the non-volatile storage media to run. The I / O interfaces are used for exchanging information between the processor and external devices. The communication interface is used for communicating with external terminals via a network connection. When the computer program is executed by the processor, it implements an optimization method for a combined cooling, heating, and power (CCHP) system.

[0069] Those skilled in the art will understand that Figure 4 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0070] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, data stored, data displayed, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of the relevant data must comply with relevant regulations.

[0071] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the embodiments described above. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM).

[0072] The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, distributed databases based on blockchain. The processors involved in the embodiments provided in this application may be, but are not limited to, general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, etc.

[0073] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0074] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. An optimization method for a combined cooling, heating and power (CCHP) system, characterized in that, The optimization method for the combined cooling, heating, and power (CCHP) system is applied to the CCHP system; the CCHP system includes: Organic Rankine cycle subsystem, absorption refrigeration cycle subsystem, and heat pump cycle subsystem; The organic Rankine cycle subsystem includes a first evaporator, a steam turbine, a first intermediate heat exchanger, a second intermediate heat exchanger, a first condenser, and a first pump. The waste heat to be recovered enters from the first inlet of the first evaporator; the first outlet of the first evaporator is connected to the steam turbine; the steam turbine is connected to the first inlet of the first intermediate heat exchanger; the first outlet of the first intermediate heat exchanger is connected to the first inlet of the first condenser; the first outlet of the first condenser is connected to the inlet of the first pump; the outlet of the first pump is connected to the second inlet of the first intermediate heat exchanger; the second outlet of the first intermediate heat exchanger is connected to the first inlet of the second intermediate heat exchanger; and the first outlet of the second intermediate heat exchanger is connected to the second inlet of the first evaporator. The absorption refrigeration cycle subsystem includes a steam generator, a gas-liquid separator, a second condenser, a first pressure reducing valve, a second evaporator, an absorber, and a second pump. The first inlet of the steam generator is connected to the second outlet of the first evaporator; the first outlet of the steam generator is connected to the inlet of the gas-liquid separator; the first outlet of the gas-liquid separator is connected to the second inlet of the second intermediate heat exchanger; the second outlet of the second intermediate heat exchanger is connected to the first inlet of the second condenser; the first outlet of the second condenser is connected to one end of the first pressure reducing valve; the other end of the first pressure reducing valve is connected to the first inlet of the second evaporator; the first outlet of the second evaporator is connected to the first inlet of the absorber; the first outlet of the absorber is connected to the inlet of the second pump; and the outlet of the second pump is connected to the second inlet of the steam generator. The heat pump cycle subsystem includes a third intermediate heat exchanger, a compressor, a third condenser, a second pressure reducing valve, and a third pressure reducing valve. The first inlet of the third intermediate heat exchanger is connected to the second outlet of the gas-liquid separator. The first outlet of the third intermediate heat exchanger is connected to one end of the compressor. The other end of the compressor is connected to the first inlet of the third condenser. The first outlet of the third condenser is connected to one end of the third pressure reducing valve. The other end of the third pressure reducing valve is connected to the second inlet of the third intermediate heat exchanger. The second outlet of the third intermediate heat exchanger is connected to one end of the second pressure reducing valve. The other end of the second pressure reducing valve is connected to the second inlet of the absorber. The optimization method for the combined cooling, heating and power system includes: Obtain the temperature of the waste heat to be recovered; Based on the temperature of the waste heat to be recovered, the critical temperature of the pre-selected working fluid, and the heat capacity of the working fluid, the optimal working fluid for the organic Rankine cycle subsystem of the cogeneration system is determined using a working fluid screening model. Based on the temperature of the waste heat to be recovered, an optimization model for the combined cooling, heating and power system is established. The optimization model takes maximizing efficiency, maximizing return on investment, and maximizing carbon dioxide emission reduction as objective functions, and uses the preset range of decision variables as constraints. The decision variables include the outlet pressure of the second pump, the heat exchange temperature difference of the steam generator, and the outlet pressure of the compressor. The optimization model is solved using a non-dominated sorting genetic algorithm to obtain the optimal decision variables, so that the combined cooling, heating and power system can recover the waste heat to be recovered based on the optimal working fluid and the optimal decision variables.

2. The optimization method for a combined cooling, heating and power system according to claim 1, characterized in that, The preselected working fluids include R1234ze(Z), R1233zd(E), 2-methylpentane, benzene, propyne, dimethyl ether, 1-chloro-3,3,3-trifluoro-1-propene, pentafluoropropane, cyclohexane, toluene, perfluorinated, 1-chloro-3,3,3-trifluoro-1-propene, dimethyl carbonate, 1,1,1,3,3-pentafluorobutane, neopentane, isobutane, isobutene, propane, butene, heptane, hexane, and 1-octane.

3. The optimization method for a combined cooling, heating and power system according to claim 1, characterized in that, Based on the temperature of the waste heat to be recovered, the critical temperature of the pre-selected working fluid, and the working fluid's heat capacity, the optimal working fluid is determined using a working fluid screening model, specifically including: Based on the temperature of the waste heat to be recovered, the critical temperature of the pre-selected working fluid, and the heat capacity of the working fluid, the comprehensive score of each pre-selected working fluid is determined using a working fluid screening model. The pre-selected working fluid with the highest comprehensive score is selected as the optimal working fluid.

4. The optimization method for a combined cooling, heating and power system according to claim 1, characterized in that, The working fluid screening model is as follows: ； Where y is the overall score of the pre-selected working fluid; The critical temperature of the working fluid; The temperature of the waste heat to be recovered; The heat capacity of the working fluid.

5. The optimization method for a combined cooling, heating and power system according to claim 1, characterized in that, The objective function is: ； ； in, For efficiency; The flow rate of the export logistics of the unit module; The flow rate of imported logistics for unit modules; This refers to the heat loss caused by heat exchange; Total output power; Total energy consumption; ROI is the return on investment. For equipment investment costs; Operating costs; The resulting economic benefits.

6. The optimization method for a combined cooling, heating and power system according to claim 1, characterized in that, The working fluid of the absorption refrigeration cycle subsystem in the cogeneration system is LiBr·H2O; the working fluid of the heat pump cycle subsystem in the cogeneration system is R1233zd(E).

7. A computer device, comprising: A memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that the processor executes the computer program to implement the optimization method for the combined cooling, heating, and power system according to any one of claims 1-6.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by a processor, the computer program implements the optimization method for the combined cooling, heating and power system as described in any one of claims 1-6.

9. A computer program product, comprising a computer program, characterized in that, When executed by a processor, the computer program implements the optimization method for the combined cooling, heating and power system as described in any one of claims 1-6.

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