Research On A Novel System Combined Cooling,Heating And Power Based On Geothermal Energy

As a kind of renewable energy,geothermal energy has the characteristics of green and pollution-free,and can reduce the dependence on non-renewable resources,which is of great significance for achieving sustainable development and building a green and beautiful society.The utilization of geothermal energy is mostly expressed in two forms: direct utilization and geothermal power generation.In the process of geothermal power generation,because geothermal water has high heat before being injected back into the ground,this part of heat is often not fully utilized.In order to make full use of geothermal resources,a novel system combined cooling,heating and power combining flash-binary cycle power generation and absorption refrigeration cycle was proposed,and the two parts of flash-binary cycle and absorption refrigeration cycle were simulated and calculated.In the flash-binary cycle system,three Kalina cycles suitable for low-temperature geothermal power generation were selected as the bottom cycle.The initial parameters of the simulation were selected by calculation and the feasibility of the system was verified.In the absorption refrigeration cycle,the working fluid pair that uses ammonia as the refrigerant was selected.Using Aspen plus software to simulate the process using ammonia-water and methylamine-water working fluid pairs,it is found that the ammonia-water absorption refrigeration cycle has better performance.On this premise,the rectification tower was calculated,the system parameters were determined,and the feasibility verification of the ammonia absorption refrigeration cycle was carried out.Combining the three designed flash-Kalina cycles with the absorption refrigeration cycle,a system combined cooling,heating and power with three different Kalina cycles as the bottom cycle,KCS-11,KCS-34 and KSG-1,was designed(F-KCS11-ARC,F-KCS34-ARC,F-KSG1-ARC).The performance of the three systems is analyzed from the perspective of thermodynamics and thermoeconomics.The thermodynamic analysis results show that: F-KCS11-ARC system has the lowest total exergy loss,F-KCS34-ARC system has the highest thermal efficiency.However,when the temperature of the geothermal source is 155-220 ?,the heat recovery efficiency of the F-KCS11-ARC system is the largest.The analysis of thermoeconomics shows that the investment cost of F-KCS11-ARC system is the lowest among the three different cold and heat power supply systems.According to the above research results,the overall performance of the F-KCS11-ARC system is better.According to the above research results,the overall performance of the F-KCS11-ARC system is better.On this basis,the F-KCS11-ARC system was further analyzed and calculated.The effects of key parameters such as flash pressure,working fluid concentration,and split ratio at the outlet of the condenser on the thermodynamic performance of the system were analyzed in detail.The optimal state has achieved the purpose of more efficient use of geothermal energy,and realized the cascade utilization of energy.The conclusion from the calculation is that the system has an optimal flash pressure of 0.3 MPa to maximize the net power generation and exergy efficiency of the system.The ammonia concentration range required for the safe operation of the system is 0.89?0.68.The coefficient of performance(COP)of the absorption refrigeration system is directly proportional to the inlet temperature of the rectification tower.With the increase of the split ratio at the condenser outlet,the total exergy efficiency of the system shows the rule of decreasing first and then increasing.Through thermal economic analysis,it is known that a higher split ratio can reduce the system investment payback period.