Study On Transition Season Performance Of Evaporative/Air Cooled Refrigeration System

In data centers,industrial plants and refrigeration and refrigeration and other fields that need perennial refrigeration,air-conditioning energy consumption accounts for a huge proportion,and the operation cost of refrigeration and air-conditioning system is high.The air-cooled refrigeration system and evaporative cooling refrigeration system are widely used because of their compact structure and convenient installation.In summer operating conditions,evaporative cooling refrigeration system takes away a large amount of condensing heat through the latent heat of water vaporization,so that the condensing pressure is maintained in a reasonable range,and the system operation energy efficiency is high.In winter,the air-cooled refrigeration system has simple structure and good refrigeration effect.However,in the transition season,the range of environmental temperature and humidity is wide,so there is no relevant research on whether the air-cooling mode or evaporative cooling mode is better for the refrigeration system.Therefore,theoretical and experimental research on the performance of evaporative cooling/air cooling hybrid refrigeration system in transition season was carried out in this paper,in order to provide a basis for the efficient operation of the refrigeration system in transition season.The evaporative cooling/air cooling combined refrigeration system studied in this paper is equipped with air cooled condenser and plate and tube evaporative cooling condenser respectively.The system can be operated in both air cooled mode and evaporative cooling mode.Based on the analysis of the heat and mass transfer process of the plate and tube evaporative condenser,the thermal performance of the air-cooled and evaporative cooling refrigeration systems in the transition season was analyzed.Then,the performance of R134 A evaporative cooling/air cooling hybrid refrigeration system in the transition season was experimentally studied,including the variation of system performance parameters under different ambient temperature,humidity,water tank temperature and exhaust temperature,air cooling mode and evaporative cooling mode.The research results show that as the operating time of the unit increases,the temperature of the water tank gradually decreases;the change of the temperature of the water tank has a greater impact on the compressor suction port parameters in the evaporative cooling mode,but has a relatively small impact on the compressor discharge port parameters;In addition,the change in water tank temperature has a greater impact on the system condenser heat exchange,evaporator heat exchange,and system COP in the evaporative cooling mode,but has a relatively small impact on the input power of the system compressor.From the perspective of system refrigeration capacity and system COP,when the throttle valve opening is 11 and the exhaust temperature is 47℃,the COP of the refrigeration system in evaporative cooling mode can reach 7.6;the larger the throttle opening,the lower the exhaust temperature The greater the amplitude,the greater the system cooling capacity and COP,and the more obvious the improvement effect of system cooling performance.In the transition season,as the ambient temperature rises,the cooling capacity and COP of the system in the air-cooling mode decrease,and the cooling capacity and COP of the system in the evaporative cooling mode decrease slowly;as the relative humidity increases,the cooling capacity and COP of the system decrease slowly;The cooling performance of the system is reduced,and the impact on the performance of the system in the air cooling mode is small.When the ambient temperature is less than 22°C and the relative humidity is greater than 64%,the cooling performance of the system in air-cooling mode is higher than that in the evaporative cooling mode;when the ambient temperature is greater than 22°C and the relative humidity is less than 64%,the cooling performance of the system in evaporative cooling mode The refrigeration performance of the system is higher than the refrigeration performance of the system in the air-cooling mode.