| The intermittency, volatility and non-periodicity of renewable energy cause the volatility of power grid when connecting with electricity generated by renewable energy and result in wind energy curtailment of wind power grid-connecting. In order to enhance the utility of renewable energy such as wind power generation, energy storage technique is more and more used in this field and the Compressed Air Energy Storage (CAES) is a dominant way in this technique. There have already been test power stations in Germany and America using conventional CAES technique studied from last century 50s and with the development of energy storage technique, the adiabatic CAES and the advanced adiabatic CAES appeared successively, while these two techniques are still not very mature, and there are a lot of blank in the study of the advanced adiabatic CAES system and its equipment. Therefore, the studies of the advanced adiabatic CAES system’s various components and the effect of various components on thermodynamic properties become a necessary issue.In order to analyze the system performance better, the paper uses the method of combining theoretical analysis and simulation and the method of experiment is used to verify the theoretical results, the main contents are as follows:Firstly, in order to study the effect of the performance of the heat exchanger on the system, the thermodynamic properties of various components of the system are analyzed and the thermodynamic model is built. Recording to the thermodynamic model, the paper operates a simulated analysis on the system and builds the simulation model of the AA-CAES system by MATLAB/simulink software. From the perspective of thermodynamics and energy conversion, taking whether there is a pressure loss and the variation of the heat exchanger effectiveness as study objects, changes of system uptime, system energy conversion characteristics and system efficiency caused by the change of the heat exchanger core parameters under four cases are analyzed. The results show that the thermal capacity flow rate z directly influences the exergy efficiency of the system; without considering the pressure loss of the heat exchanger, the overall efficiency of the system can be improved by either increasing heat exchanger effectiveness of charge process with a constant heat exchanger effectiveness of discharge process or increasing heat exchanger effectiveness of discharge process with a constant heat exchanger effectiveness of charge process; from the perspective of energy conversion, under the two cases, there is slight difference in the storage and conversion of air internal energy and heat energy in TES, and the variation of either value or position of the heat exchanger effectiveness results in a different energy utilization ratio of air internal energy and heat energy in TES; when considering the pressure loss in the heat exchanger, the system efficiency can be affected by the variation of heat exchanger effectiveness of charge or discharge process too; within a certain range, the system overall efficiency can be raised by increasing heat exchanger effectiveness, but a too high effectiveness leads a reduction of the system overall efficiency.Secondly, according to the cavern models of different thermodynamic properties, the system model is built and the thermodynamics theoretical analysis of the system is done, and the paper studies the relationship between turbine stages and the conversion and utilization of the system, and the effect of turbine stages on different cavern models, the results show that:the effect of turbine stages on the conversion and utilization of system heat energy of different cavern models is different, there is almost no effect of compressor and turbine stages on the utilization ratio of air pressure potential energy of G model and VT model systems. The utilization ratio of air pressure potential energy of P model and VA model systems decreases with the increase of compressor stages while the turbine stages have no effect on it. When adopting different turbine stages, the overall system efficiency of P model is the highest, when the compressor stages are no less than two, the overall efficiency of VA model is higher than G model and VT model, when the compressor stages are more than three, the situation is on the contrary.Thirdly, the simulation method is used to establish four types of compressed air energy storage system models, in order to obtain the energy variation principles of the system during the circulating process and how the pressure and temperature changes effecting the efficiency. The results show that, thermodynamic parameters of all the four types of cavern systems tend to be stable with the increase of cycle number. Among four models, cavern of VA model has the minimum quality and highest temperature. Heat storage temperature of four models would increase with the increase of cycle number, and gradually reach the stable maximum value, among which heat storage temperature of VA model shows the greatest temperature gap with the variation of cycle number, the highest temperature after heat release and the lowest thermal utilization rate. The system of P model has the highest overall efficiency and stability, while the overall efficiency of VA model has the greatest variety. The operation of one stage compression-expansion system with or without heat reservoir was simulated to study how the thermodynamic parameters and efficiency of the system vary from cycle number. The results show that highest efficiency is achieved without heat reservoir.Fourthly, experiment research was carried out to analyze the thermodynamic models of the cavern in the compressed air energy storage system. The temperature and pressure changing patterns with time inside the caverns during the adiabatic, isothermal and polytropic process were investigated. The experimental devices, the control system, the experimental procedure,the data acquisition systems and testing methods were introduced. The experimental results show that, the tightness and thermal insulation property of the cavern is well. The heat transfer coefficient of the cavern increases as the pressure ratio increases, but it has little effect on storage efficiency. During the charge and discharge process, the upper and lower temperature limits change with different circulation numbers, and they are also related to the upper and lower pressure limits inside the cavern. In the cycle, the charge and discharge efficiencies of the cavern are related to the upper and lower pressure limits. |
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