Research On The Thermodynamic Cycle Characteristics Of The Combined Cooling Heating And Power System Based On Renewable Energy

Nowadays, the combined cooling,heating and Power(CCHP)system usually using fuel, gas, coal and other fossil fuels as drivers is widely used in the world. The total energy utilization of the system can generally reach more than 80%. However, since fossil energy is reducing day by day and the use of fossil energy results in a series of environmental problems, which make this system fly in the ointment. Those problems can be solved by renewable energy for its renewable capability and characteristics of environmental benefits. If the renewable energy is used as the main driven energy, the system can be maintained at a relatively high efficiency and the energy can be perfectly used, so the goals of energy recycling and'Zero Emissions'can be achieved. For this purpose, a kind of CCHP which uses the solar energy and Low temperature geothermal energy as the main driven energy is established so as to be analyzed.Based on the study of kinds of CCHP system forms, finally Rankine cycle power generation system using Chloroethane as working fluid was determined after appropriate analysis and choice of the various system function modules, which refrigerated by ammonia absorption chiller and heated by solar absorption compression heat pump. On the basis of the above system, unified mathematical model of the identical characteristics of the equipments was established and a thermodynamic evaluation model of the system was proposed according to the Logistics balance equation, energy balance equation and equipment binding equation. The mathematical model of the whole system flow was formed.The practical operation is the most accurate method to test the advantages and disadvantages of the system flow, but this method is costly. Using Hysys software to simulate and analyze the system flow was a relatively better choice. In the software environment, the temperature of the solar heat collection was 74℃~ 120℃, and the temperature of the geothermal water is 90℃, the average temperature of the cold source was under 20℃, system output power 150MW, cold energy 23.6MW(-3℃), heat 2000MW(62℃).Based on the working condition, calculation analysis and various evaluation indexes of the system were carried out.Five operating conditions of the small capacity energy generation system were specially analyzed and fluctuations of various thermodynamic parameters in a day were calculated and compared. The results show that, various thermodynamic indicators are change with the fluctuation of the solar energy under the conditions of setting, and the heat of the system isn't converted into electrical energy and cold energy to the maximum extent, which requires further study to the performance of the solar heat pump. Based on the above analysis, the result that relative size ofλe,λc,λh reflects the weight distribution of the output of the electricity, cooling, heat has great guiding significance for studying the system with variable load characteristics.