Study On Effect Of Refrigerant Circuitry On Flow And Heat Transfer Performance For Air-Cooled Condenser

Circuit arrangement has great influence on flow and heat transfer performance of air-cooled condenser.The study on circuit arrangement of air-cooled condenser is helpful to optimize the existing flow and heat transfer theory and engineering design.In this paper,an experimental and simulation study was carried out to investigate the number of confluence of refrigerant on the performance of wavy finned condensers.In this paper,four six-rows-tube air-cooled condenser was carried out to investigate by experimental and simulation study,the main research object to possess the air-cooled condenser of conflux arrangement.This paper discussed the refrigerant flow rate,air face velocity and air face temperature effect on the performance of different number of refrigerant confluence refrigerant circuitry,and used the entropy generation number as the performance evaluation index of the heat exchanger is reviewed.The simulation model is validated against experimental data on one existing condenser,the results show that the air-cooled condenser three dimensional distributed parameter model of heat transfer prediction error within±10%,the refrigerant pressure drop prediction error within±15%,and used the simulation tools at a greater operation condition scope for the research object is simulated.According to the simulation results,in the range of refrigerant mass flow rate conditions,the condensers in different refrigerant circuitry have the optimal mass refrigerant flow rate range.With the increase of the number of refrigerant confluence points,the entropy generation number is gradually reduced in the appropriate mass flow rate range,and the suitable mass flow rate range will also gradually narrow.The refrigerant confluence points will increase the convective heat transfer coefficient of refrigerant side in the downstream,but almost no impact on the upstream.The optimum refrigerant mass flow rate for circuit arrangement a,c,and d are 511kg/h to 540kg/h,472kg/h to 511kg/h,and 432kg/h to 472kg/h,respectively.According to the entropy analysis,it is found that the entropy generation number of the circuit arrangement b is higher than that of the other circuit arrangement.Therefore,the circuit arrangement of the first-level confluence arrangement is not recommended in the refrigerant mass flow rate range.In the range of air face velocity conditions,the entropy generation number of all circuit arrangement decreases with the increase of air face velocity,and the decrease rate increases with the increase of the number of merge points.When u_a<2.4m/s,it is recommended to use the circuit arrangement a and b;when the range is 2.4m/s<u_a<2.7m/s,the entropy generation number of circuit arrangement b and c is relatively close;when u_a>2.7m/s,it is recommended to use the circuit arrangement d as the air-cooled condenser circuit arrangement.In the range of air face temperature conditions,with the increase of air face temperature,the entropy generation number of all circuit arrangement shows an increasing trend,and the increase rate of entropy generation number increases with the increase of the refrigerant confluence point number.When T_ai<27°C,the entropy generation number of circuit arrangement d is the smallest,and the loss of the system available-work is the smallest.When T_ai is in the range of 27°C²8.5°C,the entropy generation number of circuit arrangement b,c and d with confluence arrangement is close,the loss of available-work of the system is small,and the entropy generation number of the circuit arrangement a is large.When the T_aii is in the range of 28.5°C²9.5°C,the entropy generation number of all the circuit arrangements is close,and the difference between the system available-work of all circuit arrangements is small.When T_ai>29.5°C,the entropy generation number of circuit arrangement b,c,and d gradually increases,and the entropy generation number of circuit arrangement a becomes the smallest.