Thermodynamic And Economic Performance Analysis And Operation Optimization Research Of Combined Cooling,Heating And Power System Based On AA-CAES

In the past few decades,the worldwide consumption of non-renewable energy has increased rapidly with the rapid growth of electricity load.Therefore,problems such as high energy prices,global warming and environmental pollution continue to arise.Increasing countries around the world tend to develop renewable energy sources such as solar and wind energy to replace traditional non-renewable for power generation.However,it is difficult for renewable energy to meet the power demand due to its low power density,high site requirements and intermittent.Electric energy storage technology can effectively manage the electricity generated by renewable energy technology,becoming one of the best solutions to maintain the stability and reliability of the power system.Among these energy storage technologies,pumped hydro energy storage and compressed air energy storage(CAES)have significant advantages such as large-scale energy storage,long discharge time,and long service life,which are more suitable for consuming large-scale renewable energy.However,pumped storage power plants are restricted by topography and water sources,and their distribution is geographically dislocated from the distribution of wind and solar resources in our country.In addition,the traditional supplementary-fired CAES power plants have low energy storage efficiency,consume large amounts of fossil fuels and generate greenhouse gases.To address these deficits,advanced adiabatic compressed air energy storage(AA-CAES)was proposed,which not only has the original advantages of the traditional CAES system,but also gets rid of the dependence on fossil fuels.To meet the diversified load requirements of the clients,a combined cooling,heating and power(CCHP)system based on AA-CAES is proposed in this paper.From the perspective of thermodynamics and economics,mathematical models are established for each main component of the system.Three evaluation indicators of energy storage efficiency,energy storage density and annual profit margin are defined.On this basis,the thermodynamic and economic performance of the system are studied by simulation calculation.The main research contents are as follows:(1)To study the influence of the physical properties of different working media and heating storage media on the system performance,four combination strategies are proposed.Under the basic parameters,the performances of the systems with different strategies are compared.The influences of three key parameters on the system are analyzed,including the ambient temperature,the temperature of the low-temperature heat storage medium and the convective heat transfer coefficient.The results show that when the system adopts air as the working medium and heat transfer oil as the heat storage medium,its energy storage efficiency,energy storage density and annual profit margin are the highest.As the ambient temperature rises,the system energy storage efficiencies decrease,and the energy storage densities and annual profit margins increase.The change trend of the system performance indicators with the temperature of the low-temperature heat storage medium is opposite to that with the ambient temperature.As the convective heat transfer coefficient increases,the performance indicators of the system first decrease and then increase.(2)To study the influence of different energy storage operation modes and types of gas storage chamber(GSC)on system performance,four operation schemes are proposed.The thermodynamic performances of the systems under four different strategies are compared and analyzed,and a sensitivity analysis of the system performance is carried out.When the system adopts scheme 2(constant temperature gas storage chamber and sliding pressure operation),its energy storage efficiency and annual profit rate are the highest.When the system adopts scheme 1(constant temperature gas storage chamber and constant pressure operation),its energy storage density is the highest.When the maximum pressure ratio of the GSC increases,the energy storage efficiency of the system decreases,while the energy storage density and annual profit margin increase.When a constant-temperature GSC is adopted,the system energy storage efficiencies and densities are not affected by the compression/expansion power,and the increase in the compression/expansion power reduces the annual profit margins.When a constant-wall-temperature GSC is adopted,the increase in compression power can increase the energy storage efficiencies and energy storage densities and reduce the annual profit margins.As the expansion power increases,the system energy storage efficiencies increase,and the energy storage densities and annual profit margins decrease.(3)To balance the thermodynamic and economic performances of the systems,the non-dominant sorting genetic algorithm-II(NSGA-II)is used to carry out multi-objective optimization of the system under different operating schemes.For the systems using constant temperature gas storage chambers,when the maximum pressure ratio of the gas storage chamber is low,and the compression and expansion power are large,their optimal energy storage efficiencies are 46.64% and 48.45%,respectively.And their optimal annual profit margins are 19.53% and 26.40%,respectively.For the systems with constant-walltemperature gas storage chamber,when the maximum pressure ratio and compression power of the gas storage chamber are low,and the expansion power is large,their optimal energy storage efficiencies are 42.66% and 43.83%,respectively.And their optimal annual profit margins are 10.61% and 15.79%,respectively.