CN113446077B - Temperature optimization method for organic Rankine cycle system with heat conduction oil circulation - Google Patents

Temperature optimization method for organic Rankine cycle system with heat conduction oil circulation Download PDF

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CN113446077B
CN113446077B CN202110668609.6A CN202110668609A CN113446077B CN 113446077 B CN113446077 B CN 113446077B CN 202110668609 A CN202110668609 A CN 202110668609A CN 113446077 B CN113446077 B CN 113446077B
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纪捷
朱跃伍
王夫诚
张佳钰
秦泾鑫
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Huaiyin Institute of Technology
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Abstract

The invention relates to the technical field of low-temperature waste heat recovery, and discloses a temperature optimization method of an organic Rankine cycle system with heat conduction oil circulation. The improved grey wolf algorithm is combined to optimize the evaporation temperature and the condensation temperature, so that the effect of optimizing the overall performance of the organic Rankine cycle system is achieved.

Description

Temperature optimization method for organic Rankine cycle system with heat conduction oil circulation
Technical Field
The invention relates to the technical field of low-temperature waste heat recovery, in particular to a temperature optimization method of an organic Rankine cycle system with heat conduction oil circulation.
Background
With the acceleration of industrialization process, the problem of energy shortage has become a global problem. Along with the combustion of fossil fuels, the problem of environmental pollution is becoming serious, and energy crisis has become an urgent problem threatening our lives. Humans cannot depart from energy sources, but not all energy sources are sustainable. Accordingly, attention is now being turned away from fossil energy sources to clean, renewable and industrial waste energy sources to reduce pollution and utilize energy in a more efficient manner. Renewable energy sources, such as wind, solar and geothermal energy, are gaining increasing attention. In the industrial production process, a large amount of high-temperature waste gas is discharged by an internal combustion engine or a gas turbine, the temperature of the waste gas is usually over 200 ℃, and a large amount of medium-low temperature heat is contained in the industrial waste water, but the heat is low in recycling rate, and most of the heat is discharged as waste heat, so that the energy is wasted. Therefore, an effective energy recycling means is needed to improve the energy utilization rate and reduce the environmental pollution, thereby achieving the goal of sustainable development. An Organic Rankine Cycle (ORC) system uses waste heat or renewable energy as a heat source to convert heat energy into electric energy, which is an effective way to improve energy utilization.
Although the traditional organic Rankine cycle system improves the energy utilization rate, the heat efficiency and the net output power of the system are influenced by a plurality of factors, such as heat source temperature, working media, turbine efficiency and the like, so that the performance of the system is not stable and excellent enough, and certain limitation exists.
The evaporator and the condenser are key components of the organic Rankine cycle system, and the change of the temperature of the evaporator and the condenser has great influence on the systematicness. The evaporation temperature is an important parameter in an organic rankine cycle system. In an organic Rankine cycle system, the evaporation temperature directly influences thermodynamic state parameters of a cycle working medium in an evaporator and an expander, further influences the flow rate of the cycle working medium, the power consumption of a cycle pump, enthalpy drop of a unit working medium in the expander and the like, and further influences the thermal efficiency and the net output power of the system. In subcritical organic rankine cycle systems, the evaporation temperature is limited by the working medium critical temperature and the heat source fluid inlet temperature. When the organic Rankine cycle system operates, if the evaporation temperature is infinitely close to the critical temperature of the working medium, the enthalpy of the two-phase region tends to zero, so that the working medium flow is possibly overlarge, the working medium has a wet state in the expansion machine, and the stability of the working medium is also influenced. Therefore, the evaporation temperature is a key factor affecting the performance and stability of the system.
The condenser is also a key device in the organic Rankine cycle system, the condensation temperature is a key factor influencing the pump work consumption in the cooling water circulation, the condensation temperature is reduced, the turbine output work is increased, the cooling water flow is also increased, and the work of the circulating water pump is increased. The net work output of the system is also affected by changes in the condensing temperature, which drops sharply with decreasing condensing temperature if it is less than the optimum condensing temperature.
In order to improve the utilization efficiency of waste heat and the stability of the organic Rankine cycle power generation system, the key operation parameters of the organic Rankine cycle system need to be optimized, so that the system operates at the optimal evaporation temperature and the optimal condensation temperature, the optimal operation state is kept, and the comprehensive performance of the system is further improved.
In the existing optimization scheme, the difficulty of manually adjusting parameters is high, the optimization effect is difficult to achieve an ideal effect, the system performance cannot be comprehensively reflected, although the optimization speed is improved by the application of the algorithm such as a genetic algorithm, the algorithm has defects in the long-term generation, and the optimization precision is not superior enough.
Therefore, a novel algorithm with high optimizing speed and high accuracy is urgently needed for parameter optimization of the organic Rankine cycle system, the thermal efficiency and the net output power of the power generation system are improved to the maximum extent, and meanwhile the requirements of environmental protection and running cost saving can be met.
Disclosure of Invention
The purpose of the invention is as follows: aiming at the problems in the prior art, the invention provides the temperature optimization method of the organic Rankine cycle system with heat conduction oil circulation, which can realize deep utilization of a heat source, improve the waste heat utilization rate and the net output power of the system to the maximum extent and comprehensively improve the comprehensive performance of the system.
The technical scheme is as follows: the invention provides a temperature optimization method of an organic Rankine cycle system with heat conduction oil circulation, which comprises the following steps:
step 1: acquiring the evaporation temperature and the condensation temperature of a current evaporator and a current condenser of the organic Rankine cycle system, and establishing a dynamic mathematical model of the evaporator and the condenser according to a mass energy conservation law; initializing model parameters, wherein the parameters comprise population size, maximum iteration times and dimensionality;
step 2: initializing the population using latin hypercube sampling, determining a convergence factor a and a coefficient vector A, C, said convergence factor a being determined by the following equation:
Figure BDA0003117925840000021
wherein, t max Is the maximum iteration number;
and 3, step 3: calculating the fitness value of the wolf individual, and storing the first 3 wolfs with the best fitness as alpha, beta and delta;
and 4, step 4: updating the current grey wolf position based on an improved position updating strategy, wherein the improved position updating strategy is to perform nonlinear improvement on a position updating formula;
and 5: updating a, A and C, calculating the fitness values of all wolfs, and selecting n intelligent individuals with the front fitness;
step 6: performing chaotic search on n intelligent individual populations with the former fitness, and updating an optimal solution alpha, an optimal solution beta and a suboptimal solution delta;
and 7: and (4) judging whether the maximum iteration times is reached, if so, outputting an optimal result, and ending the optimization process, otherwise, returning to the step (4).
Further, the establishment of the dynamic mathematical models of the evaporator and the condenser in step 1 is premised on the following conditions: assuming that the organic working medium and the cooling water flow in one dimension in the evaporator and the condenser, neglecting the influence of external conditions such as pressure drop, energy loss and the like, a moving boundary method is adopted to divide the evaporator into an supercooling zone, a two-phase zone and a superheating zone, and divide the refrigerant into the superheating zone, a condensation zone and the supercooling zone in the condenser.
Further, the specific steps of the latin hypercube sampling in step 2 are as follows:
step 2.1: determining the space of dimension as N, and dividing each dimension into m intervals which are not overlapped with each other, so that each interval has the same probability;
step 2.2: randomly extracting a point in each interval in each dimension;
step 2.3: and randomly extracting points selected in the step 2.2 from each dimension, and forming vectors by using the points.
Further, the chaotic search performed in step 6 specifically includes: local search optimization is carried out by using Tent mapping, and the formula is as follows:
Figure BDA0003117925840000031
in the formula, x n Has a value range of [0,1]。
Further, in the step 4, the nonlinear improvement is performed on the position updating formula, specifically:
Figure BDA0003117925840000032
wherein, t max Is the maximum number of iterations, X 1 、X 2 、X 3 Is the direction in which the wolf individual advances toward alpha, beta and delta, and is three vectors.
Further, the organic Rankine cycle system with the heat conduction oil cycle comprises an organic Rankine cycle system, a preheating cycle system and a heat conduction oil cycle system, wherein the preheating cycle system is connected with the organic Rankine cycle system and is used for preheating working media in the organic Rankine cycle system; the heat conduction oil circulation system is connected with the organic Rankine circulation system, heat conduction oil in the heat conduction oil circulation system is heated and then sent into the organic Rankine circulation system to exchange heat with working media flowing through the organic Rankine circulation system, and therefore evaporation of the working media is achieved.
Further, the organic Rankine cycle system comprises an evaporator, an expander, a generator, a condenser, a working medium pump and a preheater, wherein the evaporator is connected with the expander, the expander is connected with the generator, the output end of the expander is connected with the condenser, the condenser is connected with the preheater through the working medium pump, the output end of the preheater is connected with the evaporator, the preheating cycle system is connected with the preheater, and the heat conduction oil cycle system is connected with the evaporator.
Further, the preheating circulation system consists of a diesel engine and the preheater, the preheater is provided with a preheater organic working medium inlet, a preheater organic working medium outlet, a preheater jacket water inlet and a preheater jacket water outlet, the diesel engine is provided with a diesel engine jacket water inlet and a diesel engine jacket water outlet, the diesel engine jacket water outlet is connected with the preheater jacket water inlet, and the preheater jacket water outlet is connected with the diesel engine jacket water inlet; the organic working medium inlet of the preheater is connected with the condenser through the working medium pump; the organic working medium outlet of the preheater is connected with the evaporator.
Furthermore, the heat conduction oil circulating system consists of a heat exchanger, the evaporator and an oil pump, wherein the heat exchanger is provided with a heat conduction oil inlet of the heat exchanger and a heat conduction oil outlet of the heat exchanger, and the evaporator is provided with an organic working medium inlet of the evaporator, an organic working medium outlet of the preheater, a heat conduction oil inlet of the evaporator and a heat conduction oil outlet of the evaporator; the heat conducting oil inlet of the heat exchanger is connected with the heat conducting oil inlet of the evaporator, and the heat conducting oil outlet of the evaporator is connected with the heat conducting oil inlet of the heat exchanger through an oil pump; the organic working medium inlet of the evaporator is connected with the organic working medium outlet of the preheater, and the organic working medium outlet of the preheater is connected with the input end of the expansion machine.
Further, still be provided with diesel engine waste heat exhanst gas outlet on the diesel engine, still be equipped with heat exchanger waste heat exhanst gas inlet and heat exchanger waste heat exhanst gas outlet on the heat exchanger, diesel engine waste heat exhanst gas outlet with heat exchanger waste heat exhanst gas inlet connection, heat exchanger waste heat exhanst gas outlet directly passes through the pipeline and discharges.
Has the beneficial effects that:
1. the invention combines the improved grey wolf algorithm to optimize aiming at the evaporation temperature and the condensation temperature, so that the system obtains the optimal operation parameters, the thermal efficiency and the net output power of the system are improved, the stability of the system operation is improved, and the comprehensive performance of the system is improved.
2. The method uses Latin hypercube sampling to initialize the wolf population, and the Latin hypercube sampling is more efficient than the common sampling method. The Laval Ding Chao cube sampling has the characteristic of uniform layering, and can obtain a sample value at the tail under the condition of less sampling, so that the Latin hypercube sampling is more efficient than a common sampling method.
3. According to the problems that the traditional wolf algorithm is low in convergence speed, unstable, prone to falling into local optimum and the like, the method and the device utilize Tent mapping to conduct local search optimization, improve algorithm accuracy and prevent falling into local optimum. The present invention non-linearises the location update formula, which balances the global search and local search processes. A nonlinear convergence factor adjusting strategy is designed, and a complex pursuit process is accurately reflected.
4. Compared with the traditional organic Rankine cycle system, the organic Rankine cycle system has the advantages that the preheating cycle system and the heat conduction oil cycle system are added, the preheating cycle system is used for carrying out waste heat on the working medium in the organic Rankine cycle system and then entering the evaporator, the working medium is convenient to evaporate, in addition, the heat conduction oil cycle system is added, the heated heat conduction oil is used for carrying out heating evaporation treatment on the working medium in the organic Rankine cycle system, the organic Rankine cycle system is enabled to continuously circulate, and the stability of the power generation system can be improved.
5. The jacket water of the diesel engine is used for preheating the working medium, so that the evaporation effect of the working medium in the subsequent link is improved, the working medium is completely evaporated into high-temperature and high-pressure gas and then enters the expander, the power generation capacity is improved, and the utilization rate of low-temperature waste heat is improved.
6. The heat conduction oil circulation of the invention also fully utilizes the heat of the waste heat smoke of the diesel engine, and the circulation of the heat conduction oil in the loop continuously heats the working medium to ensure that the working medium is completely evaporated. The heat conduction oil continuously absorbs the heat of the waste heat flue gas, so that the stability of the evaporation state of the working medium in the organic Rankine cycle is improved, the continuous utilization capacity of the system to waste heat energy is improved, the energy waste is reduced, and the deep utilization of the energy is realized by combining with the preheating link.
Drawings
FIG. 1 is a schematic diagram of an organic Rankine system with heat transfer oil circulation according to the present invention;
FIG. 2 is a flow chart of the algorithm of the present invention;
FIG. 3 is a graph comparing the primary energy savings of the present invention;
FIG. 4 is a graph showing the comparison of the heat efficiency of the R245fa cycle with the temperature of the heat source;
FIG. 5 shows a cycle with R245fa as working medium
Figure BDA0003117925840000051
Efficiency versus heat source temperature.
The system comprises an evaporator 1, an expander 2, a generator 3, a condenser 4, a working medium pump 5, a preheater 6, an oil pump 7, a heat exchanger 8, a diesel engine 9, an evaporator organic working medium inlet 11, an evaporator organic working medium outlet 12, an expander organic working medium inlet 13, an expander organic working medium outlet 14, a condenser organic working medium inlet 15, a condenser organic working medium outlet 16, a preheater organic working medium inlet 17, a preheater organic working medium outlet 18, an evaporator heat-conducting oil inlet 19, an evaporator heat-conducting oil outlet 20, a heat-conducting oil inlet 21, a heat-conducting oil outlet 22, a heat-exchanger waste heat flue gas inlet 23, a heat-exchanger waste heat flue gas outlet 24, a preheater jacket water inlet 25, a preheater jacket water outlet 26, a diesel engine jacket water inlet 27, a diesel engine jacket water outlet 28 and a diesel engine waste heat flue gas outlet 29. .
Detailed Description
The invention is further described below with reference to the accompanying drawings. The following examples are only for illustrating the technical solutions of the present invention more clearly, and the protection scope of the present invention is not limited thereby.
The invention provides a temperature optimization method of an organic Rankine cycle system with heat conduction oil circulation, which is realized based on the organic Rankine cycle system with heat conduction oil circulation, the specific structure of the system is shown in figure 1, the system comprises the organic Rankine cycle system, a preheating circulation system and the heat conduction oil circulation system, and the preheating circulation system is connected with the organic Rankine cycle system and is used for preheating working media in the organic Rankine cycle system; the heat conduction oil circulation system is connected with the organic Rankine circulation system, and heat conduction oil in the heat conduction oil circulation system is heated and then sent into the organic Rankine circulation system to exchange heat with working media flowing through the organic Rankine circulation system so as to evaporate the working media. The preheating circulating system is also connected with the heat conduction oil circulating system, and the preheating circulating system provides waste heat for the connection of the heat conduction oil circulating system to heat the heat conduction oil in the heat conduction oil circulating system.
The system specifically comprises an evaporator 1, an expander 2, a generator 3, a condenser 4, a working medium pump 5, a preheater 6, an oil pump 7, a heat exchanger 8 and a diesel engine 9. The heat conducting oil circulating system consists of a heat exchanger 8, an evaporator 1 and an oil pump 7, and the preheating circulating system consists of a diesel engine 9 and a preheater 6.
The evaporator 1 is provided with an evaporator organic working medium inlet 11, an evaporator organic working medium outlet 12, an evaporator heat-conducting oil inlet 19 and an evaporator heat-conducting oil outlet 20.
The expander 2 is provided with an expander organic working medium inlet 13 and an expander organic working medium outlet 14.
The condenser 4 is provided with a condenser organic working medium inlet 15 and a condenser organic working medium outlet 16.
The preheater 6 is provided with a preheater organic working medium inlet 17, a preheater organic working medium outlet 18, a preheater jacket water inlet 25 and a preheater jacket water outlet 26.
The heat exchanger 8 is provided with a heat exchanger heat conduction oil inlet 21, a heat exchanger heat conduction oil outlet 22, a heat exchanger waste heat flue gas inlet 23 and a heat exchanger waste heat flue gas outlet 24.
The diesel engine 9 is provided with a diesel engine jacket water inlet 27, a diesel engine jacket water outlet 28 and a diesel engine waste heat smoke outlet 29.
In an organic Rankine link, an evaporator organic working medium outlet 12 of an evaporator 1 is connected with an expander organic working medium inlet 13 of an expander 2, an expander organic working medium outlet 14 is connected with a condenser organic working medium inlet 15, a condenser organic working medium outlet 16 is connected with an input end of a working medium pump 5, an output end of the working medium pump 5 is connected with a preheater organic working medium inlet 17, and a preheater organic working medium outlet 18 is connected with an evaporator organic working medium inlet 11.
The working medium is evaporated into high-temperature high-pressure gas in the evaporator 1, the high-temperature high-pressure gas flows out of the organic working medium outlet 12 of the evaporator and enters the expansion machine 2 to do work, and the generator 3 generates electricity. The working medium flows out from an expander organic working medium outlet 14 of the expander 2, enters the condenser 4 through a condenser organic working medium inlet 15, and the gaseous working medium is condensed into a liquid working medium and flows out through a condenser working medium outlet 16. The organic working medium outlet 16 of the condenser is connected with the organic working medium inlet 17 of the preheater, and a working medium pump 5 is connected between the organic working medium outlet and the organic working medium inlet 17 of the preheater, so that the working medium is pressurized and then is sent into the preheater 6, and power is provided for the circulation of the working medium. The working medium enters the preheater 6 from the preheater organic working medium inlet 17, is preheated by a heat source, then flows out from the preheater organic working medium outlet 18, is sent to the evaporator organic working medium inlet 11 of the evaporator 1, is evaporated into high-temperature high-pressure gas by the heat source in the evaporator 1, and enters the expander 2 through the evaporator organic working medium outlet 12, so that the organic Rankine cycle is completed.
In the preheating circulation link, the preheating circulation is composed of a diesel engine 9 and a preheater 6, a diesel engine jacket water outlet 28 is connected with a preheater jacket water inlet 25, jacket water flows out from the diesel engine jacket water outlet 28 and then flows into the preheater 6 through the preheater jacket water inlet 25, and the working medium flowing through the preheater is preheated. After preheating, the jacket water flows out through the preheater jacket water outlet 26 and then enters the diesel engine through the diesel engine jacket water inlet 27 to cool the diesel engine, thereby completing the preheating cycle.
In the heat conducting oil circulation link, the heat conducting oil circulation comprises a heat exchanger 8, an evaporator 1 and an oil pump 7, a diesel engine waste heat flue gas outlet 29 of a diesel engine 9 is connected with a heat exchanger waste heat flue gas inlet 23, a heat conducting oil outlet of the heat exchanger is connected with a heat conducting oil inlet of the evaporator, a heat conducting oil outlet 20 of the evaporator is connected with a heat conducting oil inlet of the heat exchanger, and the oil pump 7 is connected between the heat conducting oil outlet and the heat conducting oil inlet of the heat exchanger.
The middle-low temperature waste heat flue gas discharged by the diesel engine 9 is discharged from a diesel engine waste heat flue gas outlet 29, is sent to the heat exchanger 8 through a heat exchanger waste heat flue gas inlet 23, heats the heat conducting oil flowing through, and is discharged from a heat exchanger waste heat flue gas outlet 24 of the heat exchanger 8. The heat conducting oil is heated in the heat exchanger 8 and flows out through the heat conducting oil outlet 22 of the heat exchanger, enters the evaporator 1 through the heat conducting oil inlet 19 of the evaporator, and exchanges heat with the working medium flowing through the heat conducting oil inlet, so that the evaporation of the working medium is realized. Heat conduction oil flows out of the evaporator 1 through the heat conduction oil outlet 20 of the evaporator, is pressurized by the oil pump 7 and then returns to the heat exchanger 8 through the heat conduction oil inlet 21 of the heat exchanger, heat exchange with waste heat flue gas is continued, the heated heat conduction oil flows out of the heat conduction oil outlet 22 of the heat exchanger and enters the evaporator 1 through the heat conduction oil inlet 19 of the evaporator, and therefore heat conduction oil circulation is achieved.
When the device is used, firstly, the jacket water discharged by the diesel engine preheats the working medium in the organic Rankine cycle, the discharged waste heat smoke realizes the evaporation of the working medium flowing out of the preheater through heat conduction oil circulation, the evaporated working medium enters the expander to do work and generate power, the working medium is condensed by the condenser, is pressurized by the working medium pump and finally returns to the preheater to preheat, and the cycle is performed.
For the organic rankine cycle system with the conduction oil cycle, during the operation process, the changes of the evaporation temperature and the condensation temperature of the evaporator 1 and the condenser 4 have a great influence on the systematicness. The evaporation temperature directly affects thermodynamic state parameters of the circulating working medium in the evaporator and the expansion machine, further affects the flow of the circulating working medium, the power consumption of the circulating pump, the enthalpy drop of unit working medium in the expansion machine and the like, and further affects the thermal efficiency and the net output power of the system. The condensing temperature is a key factor influencing the pump work consumption in the cooling water circulation, the condensing temperature is reduced, the turbine output work is increased, the cooling water flow is also increased, and the work of the circulating water pump is increased. Changes in condensing temperature also affect the net work output of the system, which decreases dramatically with decreasing condensing temperature if the condensing temperature is less than the optimum condensing temperature. In order to improve the utilization efficiency of waste heat and the stability of the organic Rankine cycle power generation system, the key operation parameters of the organic Rankine cycle system need to be optimized, so that the system operates at the optimal evaporation temperature and the optimal condensation temperature, the optimal operation state is kept, and the comprehensive performance of the system is further improved.
The invention discloses a temperature optimization method of an organic Rankine cycle system with heat conduction oil circulation, which mainly comprises the following steps:
step 1: acquiring the evaporation temperature and the condensation temperature of the evaporator 1 and the condenser 4 of the organic Rankine cycle system, and establishing a dynamic mathematical model of the evaporator 1 and the condenser 4 according to a mass energy conservation law; and initializing model parameters, wherein the parameters comprise population size, maximum iteration times and dimensionality. The establishment of the dynamic mathematical model of the evaporator and the condenser is based on the following conditions: assuming that the organic working medium and the cooling water flow in one dimension in the evaporator 1 and the condenser 4, neglecting the influence of external conditions such as pressure drop, energy loss and the like, a moving boundary method is adopted to divide the evaporator 1 into an over-cooling area, a two-phase area and an over-heating area, and the refrigerant is divided into the over-heating area, a condensation area and the over-cooling area in the condenser 4.
And 2, step: the population is initialized using latin hypercube sampling and the convergence factor a and coefficient vector A, C are determined.
When | A | >1, the wolf group will expand the enclosure to find a better prey, which corresponds to a global search at this time; when | a | <1, the grayish wolf colony will contract the enclosure to complete the final attack on the game, which corresponds to a local search. The value of A has a great relationship with the global search and local search capability of the GWO algorithm, A continuously changes along with the change of the convergence factor a, and the convergence factor a is linearly decreased from 2 to 0 along with the increase of the iteration number. However, in the actual search process, the linear reduction of a cannot accurately reflect the complex pursuit process at all. Therefore, the invention designs a nonlinear convergence factor adjustment strategy,
the convergence factor a is determined by the following formula:
Figure BDA0003117925840000081
wherein, t max Is the maximum number of iterations.
The specific steps of Latin hypercube sampling are as follows:
step 2.1: determining the space of dimension as N, and dividing each dimension into m intervals which are not overlapped with each other, so that each interval has the same probability;
step 2.2: randomly extracting a point in each interval in each dimension;
step 2.3: the points selected in step 2.2 are then randomly extracted from each dimension and grouped into vectors.
And step 3: calculating the fitness value of the wolf individual, and storing the first 3 wolfs with the best fitness as alpha, beta and delta.
And 4, step 4: updating the current gray wolf location based on an improved location update strategy, wherein the improved location update strategy is to perform nonlinear improvement on a location update formula.
The nonlinear improvement is carried out on the position updating formula, and the nonlinear improvement specifically comprises the following steps:
Figure BDA0003117925840000082
wherein, t max Is the maximum number of iterations, X 1 、X 2 、X 3 Is the direction in which the wolf individual advances toward alpha, beta and delta, and is three vectors.
And 5: and updating a, A and C, calculating the fitness values of all the wolfs, and selecting n intelligent individuals with the former fitness.
Step 6: and performing chaotic search on n intelligent individual populations with the former fitness to update the optimal solution alpha, the optimal solution beta and the suboptimal solution delta.
Local search optimization is carried out by using Tent mapping, and the formula is as follows:
Figure BDA0003117925840000083
in the formula, x n Has a value range of [0,1]。
And 7: and (4) judging whether the maximum iteration times is reached, if so, outputting an optimal result, and ending the optimization process, otherwise, returning to the step (4).
The simulation effect of fig. 3 to 5 is explained as follows:
as can be seen from fig. 3: compared with the traditional organic Rankine system, the operating time is 12 hours, and the energy saving rate of the improved organic Rankine cycle system can be improved by about 5%.
As can be seen from fig. 4 and 5: compared with an unmodified system, the organic Rankine cycle system using R245fa as a working medium has the advantages that the heat efficiency of the modified system is improved
Figure BDA0003117925840000091
The efficiency is improved, and the efficiency is increased along with the increase of the temperature of the heat source, and the performance is optimal when the temperature of the heat source is 450K.
The above embodiments are merely illustrative of the technical concepts and features of the present invention, and the purpose of the embodiments is to enable those skilled in the art to understand the contents of the present invention and implement the present invention, and not to limit the protection scope of the present invention. All equivalent changes and modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.

Claims (10)

1. The temperature optimization method of the organic Rankine cycle system with the heat conduction oil cycle is characterized by comprising the following steps of:
step 1: acquiring the evaporation temperature and the condensation temperature of a current evaporator and a current condenser of the organic Rankine cycle system, and establishing a dynamic mathematical model of the evaporator and the condenser according to a mass energy conservation law; initializing model parameters, wherein the parameters comprise population size, maximum iteration times and dimensionality;
step 2: initializing the population using latin hypercube sampling, determining a convergence factor a and a coefficient vector A, C, said convergence factor a being determined by the following equation:
Figure FDA0003117925830000011
wherein, t max Is the maximum iteration number;
and 3, step 3: calculating the fitness value of the wolf individual, and storing the first 3 wolfs with the best fitness as alpha, beta and delta;
and 4, step 4: updating the current grey wolf position based on an improved position updating strategy, wherein the improved position updating strategy is to perform nonlinear improvement on a position updating formula;
and 5: updating a, A and C, calculating the fitness values of all wolfs, and selecting n intelligent individuals with the front fitness;
step 6: performing chaotic search on n intelligent individual populations with the former fitness, and updating an optimal solution alpha, an optimal solution beta and a suboptimal solution delta;
and 7: and (4) judging whether the maximum iteration times is reached, if so, outputting an optimal result, and ending the optimization process, otherwise, returning to the step (4).
2. The method for optimizing the temperature of the organic Rankine cycle system with the conduction oil cycle according to claim 1, wherein the step 1 of establishing the dynamic mathematical model of the evaporator and the condenser is based on the following conditions: assuming that the organic working medium and the cooling water flow in one dimension in the evaporator and the condenser, neglecting the influence of external conditions such as pressure drop, energy loss and the like, a moving boundary method is adopted to divide the evaporator into an supercooling zone, a two-phase zone and a superheating zone, and divide the refrigerant into the superheating zone, a condensation zone and the supercooling zone in the condenser.
3. The temperature optimization method for the organic Rankine cycle system with the conduction oil cycle as claimed in claim 1, wherein the specific steps of Latin hypercube sampling in the step 2 are as follows:
step 2.1: determining the space of dimension as N, and dividing each dimension into m intervals which are not overlapped with each other, so that each interval has the same probability;
step 2.2: randomly extracting a point in each interval in each dimension;
step 2.3: the points selected in step 2.2 are then randomly extracted from each dimension and grouped into vectors.
4. The method for optimizing the temperature of the organic Rankine cycle system with the conduction oil cycle according to claim 1, wherein the chaotic search in the step 6 specifically comprises the following steps: local search optimization is carried out by using Tent mapping, and the formula is as follows:
Figure FDA0003117925830000021
in the formula, x n Has a value range of [0,1]。
5. The temperature optimization method for the organic Rankine cycle system with the conduction oil cycle as claimed in claim 4, wherein the step 4 is to perform nonlinear improvement on a position updating formula, and specifically comprises the following steps:
Figure FDA0003117925830000022
wherein, t max Is the maximum number of iterations, X 1 、X 2 、X 3 Is the direction in which the wolf individual advances toward alpha, beta and delta, and is three vectors.
6. The method for optimizing the temperature of the organic Rankine cycle system with the conduction oil cycle according to any one of claims 1 to 5, wherein the organic Rankine cycle system with the conduction oil cycle comprises an organic Rankine cycle system, a preheating cycle system and a conduction oil cycle system, and the preheating cycle system is connected with the organic Rankine cycle system and used for preheating working media in the organic Rankine cycle system; the heat conduction oil circulation system is connected with the organic Rankine circulation system, heat conduction oil in the heat conduction oil circulation system is heated and then sent into the organic Rankine circulation system to exchange heat with working media flowing through the organic Rankine circulation system, and therefore evaporation of the working media is achieved.
7. The temperature optimization method of the organic Rankine cycle system with the conduction oil cycle is characterized in that the organic Rankine cycle system comprises an evaporator (1), an expander (2), a generator (3), a condenser (4), a working medium pump (5) and a preheater (6), wherein the evaporator (1) is connected with the expander (2), the expander (2) is connected with the generator (3), the output end of the expander (2) is connected with the condenser (4), the condenser (4) is connected with the preheater (6) through the working medium pump (5), the output end of the preheater (6) is connected with the evaporator (1), the preheating cycle system is connected with the preheater (6), and the conduction oil cycle system is connected with the evaporator (1).
8. The temperature optimization method of the organic Rankine cycle system with the conduction oil cycle according to claim 7, wherein the preheating cycle system consists of a diesel engine (9) and the preheater (6), the preheater (6) is provided with a preheater organic working medium inlet (17), a preheater organic working medium outlet (18), a preheater jacket water inlet (25) and a preheater jacket water outlet (26), the diesel engine (9) is provided with a diesel jacket water inlet (27) and a diesel jacket water outlet (28), the diesel jacket water outlet (28) is connected with the preheater jacket water inlet (25), and the preheater jacket water outlet (26) is connected with the diesel jacket water inlet (27); the organic working medium inlet (17) of the preheater is connected with the condenser (4) through the working medium pump (5); the organic working medium outlet (18) of the preheater is connected with the evaporator (1).
9. The temperature optimization method for the organic Rankine cycle system with a thermal oil cycle according to claim 8, wherein the thermal oil cycle system is composed of a heat exchanger (8), the evaporator (1) and an oil pump (7), the heat exchanger (8) is provided with a heat exchanger thermal oil inlet (21) and a heat exchanger thermal oil outlet (22), the evaporator (1) is provided with an evaporator organic working medium inlet (11), a preheater organic working medium outlet (18), an evaporator thermal oil inlet (19) and an evaporator thermal oil outlet (20); the heat conducting oil inlet (21) of the heat exchanger is connected with the heat conducting oil inlet (19) of the evaporator, and the heat conducting oil outlet (20) of the evaporator is connected with the heat conducting oil inlet (21) of the heat exchanger through an oil pump (7); the organic working medium inlet (11) of the evaporator is connected with the organic working medium outlet (18) of the preheater, and the organic working medium outlet (18) of the preheater is connected with the input end of the expansion machine (2).
10. The temperature optimization method of the organic Rankine cycle system with the conduction oil cycle as claimed in claim 9, wherein the diesel engine (9) is further provided with a diesel engine waste heat flue gas outlet (29), the heat exchanger (8) is further provided with a heat exchanger waste heat flue gas inlet (23) and a heat exchanger waste heat flue gas outlet (24), the diesel engine waste heat flue gas outlet (29) is connected with the heat exchanger waste heat flue gas inlet (23), and the heat exchanger waste heat flue gas outlet (24) is directly discharged through a pipeline.
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