| With the rapid development of human society, human demand for energy is growing faster and faster, which has resulting in a substantial increase in the load of the traditional centralized power supply network. However, due to the temporality of human activities, large load centralized power supply network has a serious "peak and valley" problem, which has a significant adverse impact on the development of the power supply network. In addition to the "peak and valley" problems in power supply, world energy crisis which is caused by the accelerated consumption of traditional fossil fuels is also becoming more and more serious, and the extensive use of traditional fossil fuels also has brought serious environmental pollution problems, all these problems are encouraging people to search for renewable and clean energy. Just under such social background, in recent years, renewable energy such as wind energy, solar energy and tidal energy has had a large-scale growth. However, with the continuous growth of the scale of renewable energy, their own characteristics such as intermittent, dispersion and instability have become the obstacles to their own development, they also have a bad effect on the stability and reliability of the energy supply.Under the background of such a serious social energy problem, both energy storage technology and distributed generation technology have become the focus of the whole human society. Energy storage technology has the characteristics of energy storage and release at different time, it can convert and store the excess energy in the valley of energy demand, and release and supply stored energy when energy is in peak demand. The distributed generation technology can overcome the disadvantages of the traditional centralized power supply network such as redundant and complexity. Besides, it also can help to achieve energy cascade utilization, and by this way it can improve the energy utilization efficiency of the whole system. The characteristics of the two technologies make them have the potential and ability to solve the two problems, one is the traditional "peak valley power" problem, and the other is the instability of renewable energy. In this paper, based on these two technologies, a thermodynamic analysis and an experimental verification of an integrated system which combines the two technologies have been conducted.Firstly, based on literature research and statistical data, this paper shows reader the "peak and valley" problem in centralized power supply network and the development problem of renewable energy. After that, two methods to solve the two problems are put forward, which are energy storage technology and distributed energy system. Through system parameters and characteristics comparison of various energy storage technologies, we find that the compressed air energy storage technology has its own unique advantages, and it also has the potential for large-scale development. Therefore, the development history and research status of compressed air energy storage technology are studied in this paper. It is found that compressed air energy storage technology is in a period of vigorous development, and it can be classified according to its own characteristic. Adiabatic compressed air energy storage technology is one of them, which can improve energy efficiency of the whole system through the collection of heat generated in air compression process. Because of the advantages of adiabatic compressed air energy storage technology, the research status of adiabatic compressed air energy storage technology is also studied in this paper. In addition, the related literature research of distributed generation system is also carried out in this paper, and through the literature research the development status of the technology is studied. These literature research help us to know that, there is no related research for the integration of the two technologies. Therefore, one system will have both advantages of the two technologies if it can realize the integration of these two technologies. And this system is worth studying.Secondly, a distributed combined cooling heating and power system which is based on adiabatic compressed air energy storage technology is proposed in this paper. The system combines compressed air energy storage technology and distributed generation technology, which not only can realize the basic function of energy storage system, but also can realize energy cascade utilization. Low-cost "valley electricity" and renewable energy can be converted to high pressure air and thermal energy by this system, and they are stored for future use after energy conversion. In this way, this system can solve the problem that "valley electricity" and renewable energy are wasted. During the peak power time, this system can supply both mechanical power and low temperature air by the expansion of stored high pressure air. Mechanical power can drive the generator to generate electricity, so as to solve the electricity shortage problem during the peak power period. During the whole process of the system, renewable energy sources can ensure their output stability through energy storage and release process. In addition, the system is on a small scale, and air storage equipment in the system is an artificial gas tank, these characteristic ensure it be installed and operated in various geographical conditions. Therefore, this system can be integrated with micro grid, and it can become an important member of distributed energy system.Thirdly, in order to understand the system performance and the related characteristics of the system, a thermodynamic modeling study of the whole system operation process is made in the paper. Based on the thermodynamic theory, the gas parameters of each important node in the system are simplified and calculated, and the calculation is verified by the relevant test data. Based on the validated thermodynamic model, this paper also has analyzed the influence of several system parameters on the system performance. The effects of ambient temperature, the expansion ratio and the polytrophic exponent of pneumatic motor on the exhaust temperature of pneumatic motor, the specific mechanical power output and the specific cooling capacity of system are studied. Besides, the effects of initial pressure and final pressure of air storage tank on the system performance is also analyzed, and the method to decide the operating pressure of air storage tank is also discussed. Thermodynamic model calculation of the system also shows that; the use of low temperature exhaust of pneumatic motor has great significance for improving the energy efficiency of the whole system.Finally, in order to prove that the proposed system can improve energy efficiency, a comparison between the proposed system and the traditional adiabatic compressed air energy storage system is made in the paper. Based on the first and second law of thermodynamics, energy balance and exergy balance of the two systems are conducted. Thermodynamic parameters of the working medium in the two systems are calculated at each node, and exergy loss of each component in the two systems is also calculated. Several system performance parameters such as air storage time, discharge time, air mass flow rate, energy efficiency ratio of heating and cooling, mechanical power output efficiency and total exergy efficiency are compared between the two systems. In addition to the comparison of the related system parameters, the effects of ambient temperature, inlet temperature of the high pressure expansion turbine and inlet pressure of the pneumatic motor on the relevant system parameters of the two systems are also analyzed in this paper. The final results of thermodynamic contrast analysis also show us that; compared with the traditional adiabatic compressed air energy storage system, the combined cooling, heating and power system which is proposed in this paper can improve the system total exergy efficiency, and which can help to achieve the goal of more efficient use of energy. |
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