Novel combined cooling heating and power system and optimization method, equipment, medium and product thereof

Abstract

The invention discloses a novel combined cooling heating and power system and an optimization method, device, medium and product thereof, and relates to the field of low-temperature waste heat recovery. The optimization method comprises the steps that the temperature of waste heat to be recovered is obtained, the working medium critical temperature and working medium heat capacity of a preselected working medium are combined, and a preselected working medium is obtained through a working medium screening model; determining an optimal working medium of an organic Rankine cycle subsystem of the novel combined cooling heating and power system; according to the temperature of the waste heat to be recycled, an optimization model with maximum efficiency, maximum return on investment and maximum carbon dioxide emission reduction as objective functions and with a decision variable preset range as a constraint condition is established; and solving the optimization model by using a non-dominated sorting genetic algorithm to obtain an optimal decision variable, so that the novel combined cooling heating and power system recovers the waste heat to be recovered based on the optimal working medium and the optimal decision variable. The waste heat recovery efficiency of the novel CCHP system is improved.

Description

TECHNICAL FIELD

[0001] The application relates to the field of low-temperature waste heat recovery, in particular to a novel combined cooling, heat and power system and an optimization method, device, medium and product thereof. BACKGROUND

[0002] With the intensification of global climate change, the transformation of the energy field has become a global problem that needs to be solved urgently. 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 field of low-temperature waste heat recovery, combined cooling, heat and power (CCHP) systems have attracted widespread attention due to their advantages in comprehensive utilization of electricity, heat and refrigeration. However, in practical applications, the design of low-temperature waste heat recovery systems still faces a series of challenges, especially in the selection of working fluids, which is one of the key factors affecting the overall thermal efficiency and economy of the system.

[0003] Low-temperature waste heat, as a renewable energy source, has a low temperature and limited energy density, and has not been effectively utilized for a long time. However, with the continuous development of energy recovery technology, the utilization of low-temperature waste heat has gradually been valued. Traditional heat recovery systems usually rely on direct heat transfer and heat exchange methods, but these methods often have low efficiency in the recovery of low-temperature waste heat. In this context, combined heat and power (CHP) systems have emerged, which can provide both heat and electricity, improving energy recovery efficiency while reducing greenhouse gas emissions. CCHP systems have been developed on this basis, further improving the overall benefits of the system by adding a refrigeration module.

[0004] Organic Rankine Cycle (ORC) as a relatively mature low-temperature heat recovery technology has significant advantages in the utilization of low-temperature waste heat. ORC system uses organic working fluid as working fluid, which can realize the conversion and recovery of heat energy at a lower temperature, with higher energy conversion efficiency. Compared with traditional steam Rankine cycle systems, ORC systems have a lower working temperature range, suitable for low-temperature heat sources including industrial waste heat, geothermal heat, solar energy, etc. In recent years, research on ORC systems has increasingly focused on working fluid selection, thermal performance optimization, system design and economic analysis. The selection of different working fluids directly affects the efficiency and economy of the system, so the selection of working fluids has become an important direction of research.

[0005] In ORC systems, the selection of working fluid has a crucial impact on system performance. An ideal working fluid should have a low boiling point, a large expansion ratio, a high thermal conductivity, and a low environmental impact. Traditional ORC systems commonly use working fluids such as Freon, ammonia, and R245fa, but these fluids have certain limitations in terms of environmental impact, particularly 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 working fluids, such as critical temperature, critical pressure, and thermal conductivity, also directly affect the thermal efficiency and reliability of the system.

[0006] To solve 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 double-layer multi-objective optimization framework considers working fluid selection 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 is analyzed, and it is concluded that R1234ze(E) fluid has the best thermodynamic performance. In these studies, working fluid selection focuses more on optimizing the thermal efficiency and economy of the system, but in practical applications, factors such as environmental protection and sustainability of the working fluid cannot be ignored.

[0007] The optimization design of CCHP systems not only needs to consider thermodynamic performance, but also needs to comprehensively evaluate its environmental impact and economic benefits. Multi-objective optimization methods have emerged as an important means to improve the overall performance of CCHP systems. By using multi-objective optimization methods such as Genetic Algorithm (GA), Particle Swarm Optimization (PSO), and Simulated Annealing Algorithm, researchers can find an optimal compromise solution among multiple conflicting objectives.

[0008] For example, by taking the annual cost saving rate and primary energy saving rate as objective functions, and using the Non-dominated Sorting Genetic Algorithm-II (NSGA-II) to optimize the CCHP system, the results show that the system energy efficiency and energy saving effect have been significantly improved. By using the Particle Swarm Optimization (PSO) algorithm to optimize the energy efficiency, power, and cooling cost of the CCHP system, good economic benefits and energy efficiency ratio have been achieved. These studies show that multi-objective optimization methods have good prospects in improving the performance and reducing the operating cost of CCHP systems.

[0009] However, existing multi-objective optimization methods still have certain limitations. When facing high-dimensional problems, existing optimization algorithms are prone to local optimization, which leads to the inability to achieve global optimization, thereby affecting the flexibility and adaptability of the system. Therefore, in the multi-objective optimization of CCHP systems, how to improve the global search ability of the algorithm and the computational efficiency of the algorithm is still a difficult problem to be solved.

[0010] Despite the significant progress made in low-temperature waste heat recovery and CCHP system optimization, there are still some shortcomings. First, although the research on working fluid selection has made certain achievements, the thermodynamic performance of different fluids under different working conditions still lacks systematic research, especially the fluid selection problem under low-temperature waste heat recovery and special application environment has not been fully solved. Second, the complexity of CCHP system in practical application is high, involving multiple equipment and multiple target optimization, therefore, the existing optimization algorithm and model still have limitations, and cannot fully consider the mutual influence of each link in the system. In addition, existing researches mostly focus on the thermodynamic performance and economic analysis of the system, ignoring the safety, environmental impact and other problems that may occur in actual operation. Therefore, future research should pay more attention to the overall design of low-temperature waste heat recovery system, especially in the aspects of working fluid selection, equipment configuration, operation safety, etc., to further improve the adaptability and flexibility of the system.

[0011] Low-temperature waste heat recovery systems, especially combined with ORC technology, have become an important way to improve energy efficiency and reduce carbon emissions. However, the performance of the system is limited by many factors, especially the working fluid selection and system optimization problem is still a hot and difficult point of research. Future research should further explore the design of low-temperature waste heat recovery system, explore more efficient and environmentally friendly working fluids, and use more comprehensive and accurate optimization methods to improve the overall performance and economic benefits of CCHP system. SUMMARY

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

[0013] To achieve the above-mentioned purpose, the present application provides the following solutions:

[0014] In a first aspect, the present application provides a new combined cooling heating and power system, comprising: an organic Rankine cycle subsystem, an absorption refrigeration cycle subsystem and a heat pump cycle subsystem;

[0015] The organic Rankine cycle subsystem comprises a first evaporator, a 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 a first inlet of the first evaporator; a first outlet of the first evaporator is connected with the turbine; the turbine is connected with a first inlet of the first intermediate heat exchanger; a first outlet of the first intermediate heat exchanger is connected with a first inlet of the first condenser; a first outlet of the first condenser is connected with an inlet of the first pump; an outlet of the first pump is connected with a second inlet of the first intermediate heat exchanger; a second outlet of the first intermediate heat exchanger is connected with a first inlet of the second intermediate heat exchanger; a first outlet of the second intermediate heat exchanger is connected with a second inlet of the first evaporator;

[0016] The absorption refrigeration cycle subsystem comprises a steam generator, a gas-liquid separator, a second condenser, a first pressure reducing valve, a second evaporator, an absorber and a second pump; a first inlet of the steam generator is connected with a second outlet of the first evaporator; a first outlet of the steam generator is connected with an inlet of the gas-liquid separator; a first outlet of the gas-liquid separator is connected with a second inlet of the second intermediate heat exchanger; a second outlet of the second intermediate heat exchanger is connected with a first inlet of the second condenser; a first outlet of the second condenser is connected with one end of the first pressure reducing valve; the other end of the first pressure reducing valve is connected with a first inlet of the second evaporator; a first outlet of the second evaporator is connected with a first inlet of the absorber; a first outlet of the absorber is connected with an inlet of the second pump; an outlet of the second pump is connected with a second inlet of the steam generator;

[0017] The heat pump cycle subsystem comprises a third intermediate heat exchanger, a compressor, a third condenser, a second pressure reducing valve and a third pressure reducing valve; a first inlet of the third intermediate heat exchanger is connected with a second outlet of the gas-liquid separator; a first outlet of the third intermediate heat exchanger is connected with one end of the compressor; the other end of the compressor is connected with a first inlet of the third condenser; a first outlet of the third condenser is connected with one end of the third pressure reducing valve; the other end of the third pressure reducing valve is connected with a second inlet of the third intermediate heat exchanger; a second outlet of the third intermediate heat exchanger is connected with one end of the second pressure reducing valve; the other end of the second pressure reducing valve is connected with a second inlet of the absorber.

[0018] In a second aspect, the application provides an optimization method of a novel combined cooling, heating and power system, comprising:

[0019] Obtaining the temperature of the waste heat to be recovered;

[0020] According to the temperature of the waste heat to be recovered, the critical temperature of the preselected working medium, and the heat capacity of the working medium, an optimal working medium of the organic Rankine cycle subsystem of the new combined cooling, heating and power system is determined by using a working medium screening model;

[0021] According to the temperature of the waste heat to be recovered, an optimization model of the new 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 takes a preset range of decision variables as constraint conditions; the decision variables include an outlet pressure of the second pump, a heat exchange temperature difference of the steam generator, and an outlet pressure of the compressor;

[0022] The optimization model is solved by using a non-dominated sorting genetic algorithm to obtain optimal decision variables, so that the new combined cooling, heating and power system recovers the waste heat to be recovered based on the optimal working medium and the optimal decision variables.

[0023] Optionally, the preselected working medium includes R1234ze (Z), R1233zd (E), 2-methylpentane, benzene, propyne, dimethyl ether, 1-chloro-3, 3, 3-trifluoro-1-propene, pentafluoropropane, cyclohexane, toluene, perfluoro, 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.

[0024] Optionally, according to the temperature of the waste heat to be recovered, the critical temperature of the preselected working medium, and the heat capacity of the working medium, an optimal working medium is determined by using a working medium screening model, and specifically includes:

[0025] According to the temperature of the waste heat to be recovered, the critical temperature of the preselected working medium, and the heat capacity of the working medium, an optimal working medium is determined by using a working medium screening model, and specifically includes:

[0026] The preselected working medium with the highest comprehensive score is taken as the optimal working medium.

[0027] Optionally, the working medium screening model is:

[0028]

[0029] wherein y is the comprehensive score of the preselected working medium; T C is the critical temperature of the working medium; T W is the temperature of the waste heat to be recovered; and C P is the heat capacity of the working medium.

[0030] Optionally, the objective function is:

[0031]

[0032] wherein ηE For efficiency; For the flow rate of the unit module outlet stream; For the flow rate of the unit module inlet stream; For the loss due to heat exchange; W out For the total output work; W in For the total consumed work; ROI is the return on investment; C e For the equipment investment cost; C op For the operating cost; C P For the economic benefit generated; CER is the carbon dioxide emission reduction; For the carbon dioxide conversion coefficient; t OP For the annual operating time; W tot For the equivalent output power.

[0033] Optionally, the working medium of the absorption refrigeration cycle subsystem in the new combined cooling, heating and power system is LiBr·H2O; and the working medium of the heat pump cycle subsystem in the new combined cooling, heating and power system is R1233zd(E).

[0034] In a third aspect, the present application provides a computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, and the processor executes the computer program to implement the optimization method of the new combined cooling, heating and power system according to any one of the above.

[0035] In a fourth aspect, the present application provides a computer readable storage medium, which stores a computer program executable by a processor to implement the optimization method of the new combined cooling, heating and power system according to any one of the above.

[0036] In a fifth aspect, the present application provides a computer program product comprising a computer program executable by a processor to implement the optimization method of the new combined cooling, heating and power system according to any one of the above.

[0037] According to the specific embodiments provided by the present application, the present application has the following technical effects:

[0038] The present application provides a new combined cooling, heating and power system and an optimization method, device, medium and product thereof. The new combined cooling, heating and power system comprises an organic Rankine cycle subsystem, an absorption refrigeration cycle subsystem and a heat pump cycle subsystem. The temperature of the waste heat to be recovered is obtained; the optimal working medium of the organic Rankine cycle subsystem is determined by using a working medium screening model according to the temperature of the waste heat to be recovered, the critical temperature of the preselected working medium and the heat capacity of the working medium; the optimization model of the new combined cooling, heating and power system is established according to the temperature of the waste heat to be recovered; the optimization model is used to maximize Efficiency, maximizing the rate of return on investment and maximizing carbon dioxide emissions reduction as the objective function, with the decision variable preset range as the constraint condition; the non-dominated sorting genetic algorithm is used to solve the optimization model, and the optimal decision variable is obtained, so that the new combined cooling heating and power system recovers the waste heat based on the optimal working medium and the optimal decision variable. The working medium screening model suitable for the ORC system is established from the working medium critical temperature, heat capacity and waste heat temperature, the optimal working medium is determined, and the new CCHP system is comprehensively analyzed from the aspects of economy and environment. 、economic and environmental analysis, from 、economic, environmental and environmental point of view, multi-objective optimization is carried out, and the optimal decision variable is obtained, so as to improve the efficiency of waste heat recovery of the new CCHP system. BRIEF DESCRIPTION OF DRAWINGS

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0040] Figure 1 A schematic structural diagram of a new combined cooling heating and power system is provided for an embodiment of the present application.

[0041] Figure 2 A flow chart of the optimization method of the new combined cooling heating and power system is provided.

[0042] Figure 3 A schematic diagram of the Pareto front result of multi-objective optimization is provided.

[0043] Figure 4 A schematic structural diagram of a computer device is provided for an embodiment of the present application. DETAILED DESCRIPTION

[0044] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0045] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the present application will be further described in detail below with reference to the drawings and specific embodiments.

[0046] In an exemplary embodiment, as shown in Figure 1As shown, a new combined cooling heating and power system is provided, comprising: an organic Rankine cycle subsystem, an absorption refrigeration cycle subsystem and a heat pump cycle subsystem. Wherein CW is cooling water, CWR is cooling water return.

[0047] The organic Rankine cycle subsystem comprises a first evaporator EVA1, a 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 enters from the first inlet of the first evaporator EVA1 (i.e. Figure 1 Heat sourec in, heat source input); the first outlet of the first evaporator EVA1 is connected with the turbine TUR; the turbine TUR is connected with the first inlet of the first intermediate heat exchanger HEATX1; the first outlet of the first intermediate heat exchanger HEATX1 is connected with the first inlet of the first condenser CON1; the first outlet of the first condenser CON1 is connected with the inlet of the first pump PUMP1; the outlet of the first pump PUMP1 is connected with the second inlet of the first intermediate heat exchanger; the second outlet of the first intermediate heat exchanger HEATX1 is connected with the first inlet of the second intermediate heat exchanger HEATX2; the first outlet of the second intermediate heat exchanger HEATX2 is connected with the second inlet of the first evaporator EVA1.

[0048] The absorption refrigeration cycle subsystem comprises 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 with the second outlet of the first evaporator EVA1; the first outlet of the steam generator GEN is connected with the inlet of the gas-liquid separator SEP; the first outlet of the gas-liquid separator SEP is connected with the second inlet of the second intermediate heat exchanger HEATX2; the second outlet of the second intermediate heat exchanger HEATX2 is connected with the first inlet of the second condenser CON2; the first outlet of the second condenser CON2 is connected with one end of the first pressure reducing valve VALUE1; the other end of the first pressure reducing valve VALUE1 is connected with the first inlet of the second evaporator EVA2; the first outlet of the second evaporator EVA2 is connected with the first inlet of the absorber ABS; the first outlet of the absorber ABS is connected with the inlet of the second pump PUMP2; the outlet of the second pump PUMP2 is connected with the second inlet of the steam generator GEN.

[0049] The heat pump circulation 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.

[0050] This application develops a new CCHP system, such as Figure 1 As shown in the figure, this system consists of three subsystems: the ORC, the ARC (Absorption Refrigeration Cycle), and the HPC (Heat Pump Cycle), achieving cascaded energy utilization. Waste heat first enters the first evaporator EVA1, heating the working fluid in the ORC system. Once heated to a gaseous state, the working fluid drives the steam turbine TUR to generate electricity. Because the working fluid at the outlet of the steam turbine TUR needs to be condensed by cooling water and enters the first evaporator EVA1, the working fluid needs to be heated. Therefore, a first intermediate heat exchanger, HEATX1, is added for heat exchange, saving utility cooling water and improving waste heat utilization efficiency. The heat-exchanged working fluid then 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 to remove the waste heat before entering the evaporator for complete vaporization.

[0051] After passing through the ORC system, the waste heat 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 reduced in pressure by the first pressure reducing valve VALUE1, it enters the second evaporator EVA2 to produce chilled water. The liquid phase stream passing through the gas-liquid separator SEP is used to heat the working fluid of the HPC system. After being reduced in pressure by the second pressure reducing valve VALUE2, it enters the absorber ABS together with the working fluid at 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 through the second outlet (heat source out) of the steam generator GEN. The working fluid in the HPC system is vaporized in the third intermediate heat exchanger HEATX3 and enters the compressor COM for quality improvement before entering the third condenser CON3 to output high-quality heat. It then enters the third pressure reducing valve VALUE3 for pressure reduction before returning to the third intermediate heat exchanger HEATX3. At this point, the CCHP system completes the process of producing high-quality cold energy, heat energy, and electrical energy from low-temperature waste heat.

[0052] In one embodiment, Figure 2 As shown, the present application provides a novel optimization method for a combined cooling, heating and power system, comprising:

[0053] S1: Obtain the temperature of waste heat to be recovered.

[0054] S2: Determine the optimal working fluid for the organic Rankine cycle subsystem of the novel combined cooling, heating and power system using a working fluid screening model based on the waste heat temperature to be recovered, the critical temperature of the preselected working fluid, and the working fluid heat capacity.

[0055] As an optional embodiment, 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), isobutylene, propane (R601a, R600), butene, heptane, hexane, and 1-octane.

[0056] As an optional implementation, S2 specifically includes:

[0057] S21: Determine a comprehensive score of each preselected working fluid using a working fluid screening model according to the temperature of the waste heat to be recovered, the critical temperature of the preselected working fluid, and the working fluid heat capacity.

[0058] The working medium screening model is:

[0059]

[0060] Wherein, y is the comprehensive score of the preselected working medium; T C is the critical temperature of the working medium; T W is the temperature of the waste heat to be recovered; C P is the heat capacity of the working medium.

[0061] S22: taking the preselected working medium with the highest comprehensive score as the optimal working medium.

[0062] In actual application, a working medium screening model is constructed to screen the optimal working medium.

[0063] The ORC system working medium screening method provided in the application comprises the following steps: using Aspen Plus to construct an ORC process flow model; selecting 24 preselected working media covering environmental protection type and conventional type; obtaining working medium thermophysical property data from NIST REFPROP 10.0; developing a working medium screening program by using Python, automatically calling Aspen Plus for calculation and searching for optimal parameters; calculating the ORC power generation efficiency of the working medium under different heat source temperatures, analyzing the influence of physical properties and considering environmental protection safety; screening the optimal working medium; and the properties of the preselected working media are shown in Table 1.

[0064] Table 1: Basic property table of the working media to be selected

[0065]

[0066] In this embodiment, 7 different waste heat temperatures of 150℃, 140℃, 130℃, 120℃, 110℃, 100℃ and 90℃ are selected in the low temperature range for research. The cycle thermal efficiency is selected as the objective function, as shown in formula (1), and the pressures of the pump and the expander (turbine) are the manipulated variables to find the optimal operating parameters.

[0067]

[0068] Wherein, η is the cycle thermal efficiency; W TUR is the turbine output power; W PUMP is the pump consumption power; Q EVA is the evaporator heat load.

[0069] In order to ensure the stable operation of the ORC system, the following limiting conditions are added:

[0070] In order to ensure that the working medium can be condensed by the cooling water, the outlet temperature of the expander is set to be greater than the outlet temperature of the cooling water, that is:

[0071] T TUR,out ≥ 40℃ (2)

[0072] wherein T TUR,out is the expander outlet temperature.

[0073] Subcritical ORC system is discussed, so the pressure of the working fluid pump is set to be less than the subcritical pressure, i.e.

[0074] P PUMP ≤ 0.9P c (3)

[0075] wherein P PUMP is the pressure of the working fluid pump; P c is the critical pressure of the working fluid.

[0076] To ensure that the expander is not damaged and prolong its service life, the outlet flow is set to contain no liquid phase, and the inlet pressure is set to be lower than the saturated vapor pressure of the working fluid at the evaporation temperature, i.e.

[0077]

[0078] wherein a TUR,out is the gas phase fraction at the turbine outlet; P Eva,in is the inlet pressure of the evaporator; is the saturated vapor pressure of the working fluid at the evaporation temperature.

[0079] To ensure that the expander outlet steam is not superheated and can be successfully condensed, the outlet pressure is set to be greater than the saturated vapor pressure of the working fluid at 40℃, i.e.

[0080]

[0081] wherein P TUR,out is the outlet pressure of the expander; is the saturated vapor pressure of the working fluid at 40℃.

[0082] This embodiment considers key factors such as greenhouse gas potential GWP, ozone depletion potential ODP, and safety of the working fluid. To take into account the thermal efficiency, environmental impact, and safety, the TOPSIS (Technique for Order Preference by Similarity to Ideal Solution, multi-attribute decision-making) method is used to quantitatively analyze different working fluids, so as to screen out the optimal working fluid. The ORC system working fluid with the highest comprehensive score is 1-chloro-3,3,3-trifluoropropene (R1233zd(E)), so R1233zd(E) is used as the working fluid of the ORC system. In this embodiment, the ARC system working fluid uses LiBr·H2O, and the HPC system working fluid uses R1233zd(E).

[0083] In addition, in order to further explore the relationship between the working medium thermal efficiency and its key thermodynamic properties, the embodiment combines the working medium critical temperature, the working medium heat capacity and the heat source temperature (waste heat temperature) and other variables to perform regression analysis. The working medium screening model is shown in formula (6):

[0084]

[0085] Wherein, T C is the working medium critical temperature (K), T W is the waste heat temperature (K), C P is the working medium heat capacity (cal / (mol·K)).

[0086] The determination coefficient of the regression model (working medium screening model) is 0.9604, indicating that the model can more accurately reflect the relationship between these variables and the cycle thermal efficiency, thereby providing a more accurate theoretical basis for the selection of working medium.

[0087] S3: According to the to-be-recovered waste heat temperature, an optimization model of the new combined cooling, heating and power system is established; the optimization model takes the maximum efficiency, the maximum return on investment and the maximum carbon dioxide emission reduction as objective functions, and takes the preset range of decision variables as constraint conditions; 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.

[0088] As an optional implementation, the objective function is:

[0089]

[0090] Wherein, η E is the efficiency; is the flow rate of the outlet stream of the unit module; is the flow rate of the inlet stream of the unit module; is the loss due to heat exchange; W out is the total output power; W in is the total consumed power; ROI is the return on investment; C e is the equipment investment cost; C op is the operating cost; C P is the economic benefit generated; CER is the carbon dioxide emission reduction; is the carbon dioxide conversion coefficient; t OP is the annual operating time; W tot is the equivalent output power.

[0091] In practical applications, based on the results obtained from the above working fluid screening mechanism model, a new CCHP system was developed, such as Figure 1 shown.

[0092] S4: Solve the optimization model using a non-dominated sorting genetic algorithm to obtain optimal decision variables, so that the novel combined cooling, heating and power system recovers 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 novel combined cooling, heating and power system is LiBr·H2O; the working fluid of the heat pump cycle subsystem in the novel combined cooling, heating and power system is R1233zd(E).

[0093] In practical applications, this embodiment uses 145°C waste heat as the system heat source. The above system can also recover low-temperature waste heat at other temperatures, but the system operating parameters (decision variables) need to be adjusted. To ensure that the new CCHP system operates under the optimal operating parameters to maximize With the goals of efficiency, maximizing return on investment, and maximizing carbon dioxide emission reduction, a comprehensive evaluation of system performance was conducted. The results of the working fluid screening model, R1233ZD(E), were selected as the working fluid for the ORC and HPC subsystems. The PUMP2 outlet pressure, GEN heat exchange temperature difference, and COM outlet pressure were selected as decision variables for a multi-objective optimization of the new CCHP system. The objective function calculation method is as follows:

[0094] CCHP system The efficiency can be expressed as:

[0095]

[0096] Different modules The calculation method is shown in Table 2.

[0097] Table 2 Modules Analysis method statistics table

[0098]

[0099]

[0100] Return on Investment (ROI) is used to evaluate whether an investment is worthwhile. A higher value indicates a more efficient investment. It can be expressed as:

[0101]

[0102] Among them, C gen is the economic benefit generated ($), C op is the annual operating cost ($), C eThe investment cost of the equipment (USD).

[0103] CO2 has been the main contributor to greenhouse gas emissions, and the recovery of low-temperature waste heat to generate high-grade energy to minimize CO2 emissions is one of the key indicators for evaluating new CCHP systems. This embodiment uses annual CO2 reduction to evaluate, which can be expressed as

[0104]

[0105] where CER is the annual CO2 emission reduction (t),

[0106] To ensure technical and economic feasibility, a set of constraints (i.e., the corresponding set range of each decision variable) is imposed on the decision variables during optimization. The optimization uses a non-dominated sorting genetic algorithm, and the specific parameters of the algorithm are shown in Table 3: the population size is 500, and the iteration number is 500 generations. Through this optimization method, the Pareto front composed of Pareto optimal solutions can be obtained, and the Pareto optimal solution refers to the solution that cannot be improved by simultaneously improving all objectives between multiple objective functions, and the results are shown in Figure 3 .

[0107] Table 3 Genetic algorithm parameter setting table

[0108]

[0109]

[0110] To further select the optimal operating point of the system, the entropy weight method is used to calculate the weight of each objective function. The advantage of the entropy weight method is that it can objectively determine the weight according to the data itself, avoiding the subjective bias that may be brought by manually setting the weight. Subsequently, the Pareto front is comprehensively evaluated by the TOPSIS method, and the optimal solution is selected, as shown in Figure 3 , where point A has the maximum ROI and CER, but its η ex is the lowest. Point B has the maximum η ex , but its ROI and CER are the lowest. Point D is the ideal point, which simultaneously satisfies the optimal solution of the three objective functions. Point C is the optimal operating point selected by TOPSIS, which maximizes the emission reduction benefit and investment return while ensuring that the system meets the high performance demand; Pareto front is the Pareto front; Optimal operating point is the best working point. This method effectively takes into account the relative importance of each optimization objective, providing a more scientific decision basis for the design and operation of the system. When the decision variables P PUMP1 , P TUR , TGEN The optimal operating state of the new CCHP system is obtained at 14.37 kPa, 9.0 bar and 5.2 K, respectively, with η E , CER and ROI being 0.80, 1958 t / year and 0.5377, respectively. Compared with the original CCHP system, the efficiency of the new CCHP system is increased from 0.78 to 0.80, the ROI is increased from 0.4990 to 0.5377, and the CER is increased to 1958 t / year, which indicates that the optimization design effectively reduces the initial investment cost through equipment selection and process improvement, and brings higher returns to investors. The efficiency is increased from 0.78 to 0.80, the ROI is increased from 0.4990 to 0.5377, and the CER is increased to 1958 t / year, which indicates that the optimization design effectively reduces the initial investment cost through equipment selection and process improvement, and brings higher returns to investors.

[0111] The present application establishes a working medium screening model suitable for ORC systems based on the critical temperature, heat capacity and waste heat temperature of the working medium, with a determination coefficient of 0.9604, which provides scientific guidance for system design and optimization under similar heat source conditions. In addition, a comprehensive , economic and environmental analysis is conducted on the new CCHP system, quantifying the operating characteristics and optimization potential of the system. From the perspectives of , economy and environment, the proposed system is subjected to multi-objective optimization. The system optimization reduces the initial investment and operating costs, shortens the investment recovery period, and reduces energy procurement costs through energy saving. The system reduces greenhouse gas emissions, promotes sustainable development and environmental protection. It is suitable for various scenarios such as industry, commerce and residence, and has good system stability and flexibility.

[0112] In an exemplary embodiment, a computer device is provided, comprising a memory and a processor, the memory storing a computer program, and the processor implementing the optimization method of the new combined cooling heating and power system when executing the computer program.

[0113] In an exemplary embodiment, a computer readable storage medium is provided, storing a computer program, which, when executed by a processor, implements the optimization method of the new combined cooling heating and power system.

[0114] In an exemplary embodiment, a computer program product is provided, comprising a computer program, which, when executed by a processor, implements the optimization method of the new combined cooling heating and power system.

[0115] In an exemplary embodiment, a computer device is provided, which can be a server or a terminal, and its internal structure diagram can be as shown in Figure 4As shown in the figure. The computer device includes a processor, a memory, an input / output interface (Input / Output, referred to as I / O) and a communication interface. Among them, the processor, the memory and the input / output interface are connected through the system bus, and the communication interface is connected to the system bus through the input / output interface. Among them, the processor of the computer device is used to provide computing and control capability. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The input / output interface of the computer device is used to exchange information between the processor and the external device. The communication interface of the computer device is used to communicate with the terminal outside through the network connection. The computer program is executed by the processor to realize a new type of combined cooling, heating and power generation system optimization method.

[0116] Those skilled in the art can understand that, Figure 4 The skilled in the art can understand that,

[0117] It should be noted that the user information (including but not limited to user equipment information, user personal information, etc.) and data (including but not limited to data for analysis, stored data, displayed data, etc.) involved in the present application are all information and data authorized by the user or authorized by all parties, and the collection, use and processing of related data need to comply with relevant regulations.

[0118] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a non-volatile computer readable storage medium, and when the computer program is executed, the processes of the above-mentioned embodiments of the methods can be included. Any reference to memory, databases or other media used in the embodiments provided in the present 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 storage, high-density embedded non-volatile memory, resistive memory (ReRAM), magnetoresistive random access memory (MRAM), ferroelectric memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. As an illustration but not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM), etc.

[0119] The database involved in the embodiments provided in the present application can include at least one of a relational database and a non-relational database. The non-relational database can include a distributed database based on a blockchain, etc., without being limited thereto. The processor involved in the embodiments provided in the present application can be a general-purpose processor, a central processing unit, a graphics processing unit, a digital signal processor, a programmable logic device, a data processing logic device based on quantum computing, etc., without being limited thereto.

[0120] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, all possible combinations of the technical features in the above embodiments are not described, but as long as the combinations of the technical features do not exist contradictory, they should be considered as the scope of the present application.

[0121] The principles and implementation modes of the present application are described by applying specific examples herein. The above description of the embodiments is only used to help understand the method and its core idea of the present application; meanwhile, for those skilled in the art, according to the idea of the present application, the specific implementation mode and application range can be changed. In conclusion, the content of the present application should not be understood as a limitation.

Claims

1. A new type of combined cooling, heating and power system, characterized in that: include: 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; 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 circulation 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; and the other end of the second pressure reducing valve is connected to the second inlet of the absorber.

2. A novel optimization method for a combined cooling, heating and power system, characterized in that: include: Obtain the temperature of waste heat to be recovered; According to the temperature of the waste heat to be recovered, the critical temperature of the preselected working fluid, and the working fluid heat capacity, a working fluid screening model is used to determine the optimal working fluid for the organic Rankine cycle subsystem of the novel combined cooling, heating and power system of claim 1; According to the temperature of the waste heat to be recovered, an optimization model of a new type of combined cooling, heating and power system is established; the optimization model is used to maximize The objective function is to maximize efficiency, return on investment, and carbon dioxide emission reduction, with 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 optimal decision variables, so that the novel combined cooling, heating and power system can recover the waste heat to be recovered based on the optimal working medium and the optimal decision variables.

3. The optimization method of the novel combined cooling, heating and power system according to claim 2, 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, perfluoro, 1-chloro-3,3,3-trifluoro-1-propene, dimethyl carbonate, 1,1,1,3,3-pentafluorobutane, neopentane, isobutane, isobutylene, propane, butene, heptane, hexane, and 1-octane.

4. The optimization method of the novel combined cooling, heating and power system according to claim 2, characterized in that: According to 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 is determined using a working fluid screening model, specifically including: Determining a comprehensive score of each preselected working fluid using a working fluid screening model based on the waste heat temperature to be recovered, the critical temperature of the preselected working fluid, and the working fluid heat capacity; The preselected working fluid with the highest comprehensive score is used as the optimal working fluid.

5. The optimization method of the novel combined cooling, heating and power system according to claim 2, characterized in that: The working fluid screening model is: Where y is the comprehensive score of the pre-selected working fluid; T C is the critical temperature of the working fluid; T W is the temperature of waste heat to be recovered; C P is the heat capacity of the working fluid.

6. The optimization method of the novel combined cooling, heating and power system according to claim 2, characterized in that: The objective function is: Among them, η E for efficiency; For unit module export logistics flow rate; For unit module import logistics flow rate; The heat generated by Loss; W out is the total output power; W in is the total power consumption; ROI is the return on investment; C e C is the equipment investment cost; op C is the operating cost; P is the economic benefit generated; CER is the carbon dioxide emission reduction; is the carbon dioxide conversion coefficient; t OP is the annual operating time; W tot is the equivalent output power.

7. The optimization method of the novel combined cooling, heating and power system according to claim 2, characterized in that: The working fluid of the absorption refrigeration circulation subsystem in the novel combined cooling, heating and power system is LiBr·H2O; the working fluid of the heat pump circulation subsystem in the novel combined cooling, heating and power system is R1233zd(E).

8. A computer device comprising: 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 the novel combined cooling, heating, and power system according to any one of claims 2 to 7.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the optimization method of the novel combined cooling, heating and power system according to any one of claims 2 to 7 is implemented.

10. A computer program product comprising a computer program, characterized in that When the computer program is executed by a processor, the optimization method of the novel combined cooling, heating and power system according to any one of claims 2 to 7 is implemented.

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