| Solar thermal power plants are generally built in the northern,northeast,and northwest regions and the composite cycle air cooling technology can solve the problem of water shortage,and have an advantage than the direct air cooling technology.Based on the structure composition and heat transfer process of indirect air cooled system with compound refrigeration cycle(CRC-IAC)system,The effects of pipe wall temperature,inlet flow rate of liquid ammonia and inlet temperature on the heat transfer of the condenser were analyzed qualitatively.The influencing factors of the heat transfer between the condensers for CRC-IAC system were determined,the calculation model of phase change heat exchanger(condenser)under off-designed operation of CRC-IAC system was established,and the optimal heat transfer area of the cooling system was determined as the optimization objective.A calculation method of optimal heat transfer area of CRC-IAC system under operation conditions was formed.Based on the parameters of the 50 MW solar thermal power generation and refrigeration system in Zhangbei area,the optimum heat transfer rules of condensers for the CRC-IAC system were revealed by analysis and calculation.The results can be designed and optimized for the CRC-IAC system to Provide a reliable theoretical basis.(1)The numerical simulation of the evaporation of the vapor-liquid two-phase flow in the air-cooled condenser of the air-cooled condenser of the power station is carried out.The heat exchanger is simplified to study a single horizontal heat transfer tube,the effects of pipe wall temperature,inlet flow rate of liquid ammonia and inlet temperature on boiling heat transfer performance were analyzed.The results show when the increase of the tube wall temperature,the heat transfer coefficient becomes smaller.With the increase of the inlet flow rate of the liquid ammonia,the heat transfer performance of the tube increases,and the pressure inside the tube decreases.With the increase of the liquid ammonia inlet temperature in tube heat transfer performance is declining,and the pressure is almost no change.(2)To determine the combination of the optimal wall temperature,inlet flow rate,inlet temperature.The results show that the heat transfer effect of the heat exchanger is the best when the wall temperature is 302.96 K,the inlet flow rate is 0.1m/s and the inlet temperature is 278.15 K.The optimal heat transfer area of the heat exchanger can be determined by combining the optimal wall temperature of the condenser,the inlet flow rate of the liquid ammonia and the inlet temperature with the actual operating environment of the power station.(3)In this paper,the model of the anti-cycle air-cooling system is established,and the model of the anti-cycle air-cooling system is simulated by EES(Engineering Equation Solver)software.through performance analysis and thermal optimization research.In this paper,the enthalpy efficiency of evaporator temperature,condensing temperature,superheat degree,condensing temperature,ambient temperature and expander as key performance parameters as a performance evaluation index for Rankine system were selected from the perspectives of irreversible loss,expansion power output,system thermal efficiency and exergy efficiency.The entropy efficiency of the evaporator temperature,the ambient temperature and the expander are the beneficial factors of the improvement of the system performance.The increase of the condensing temperature is the unfavorable factor for the improvement of the system performance.The superheat degree has little effect on the system performance,The system is beneficial,but the benefit is small.(4)The model of positive cooling cycle air cooling system is established.The EES is used to calculate the evaporation temperature and the ambient temperature is favorable to the system.The condensation temperature and superheat degree are unfavorable to the system,subcooling temperature has no effect on the system. |
PDF Full Text Request