Simulation And Experimental Study On Performance Of Combined Air Conditioner And Freezer System

The energy consumption of refrigeration systems in the convenience stores and small supermarkets accounts for more than 50%,which has great potential for energy conservation.Therefore,the study of energy saving measures for its refrigeration systems is of great significance.An experimental system of combined air-conditioner and freezer(CACF)system was presented in this paper.The part of the refrigerant in the air conditioner system with the refrigerant R410 A is throttled into the intermediate subcooler,in which the refrigerant R404 A of the freezer system is subcooled.At the same time,the condenser of freezer and the outdoor heat exchanger of air conditioner is designed as an integrated heat exchanger to prevent frosting of the air conditioner evaporator under winter conditions.Compared with the traditional mechanical subcooling system,the existing air conditioning system is used as an auxiliary cycle in the CACF,which saves initial investment.The effects of mass flow ratio on the cooling capacity,power consumption,supercooling degree,and COP of the air conditioner and freezer under different environmental conditions where simulates and analyzes.The mass flow ratio refers to the ratio of the mass flow rate of the air-conditioning system into the intercooler to the total air conditioner mass flow rate.The performance of the CACF system was measured under different environmental conditions.And cooling capacity,power consumption,supercooling degree,and COP of air conditioner and freezer were analyzed.The main conclusions are as follows:(1)The results of theoretical simulation show that the use of partial refrigerant throttling of the air conditioner system to subcool the freezer system can effectively increase the supercooling degree of the freezer system.The mass flow ratio increases by 4%,the supercooling degree increases by approximately 5°C,and the cooling capacity and COP of the freezer increases;The cooling capacity and COP of the air conditioner system have a small decrease with the mass flow ratio,and the reduced rate decreases with the increase of the mass flow ratio.(2)The experimental results under winter conditions show that the increase of the mass flow ratio can improve the cooling capacity and COP of the freezer system,andthe increase is the most in the range of 0.08~0.12 of mass flow ratio;The heating capacity of the air conditioner system is unchanged with the increase of the mass flow ratio,at the same time,the compressor power consumption is reduced and the COP is increased.(3)The experimental results under winter conditions show that the increase in freezer temperature can increase the cooling capacity and COP of the freezer,and the change of freezer temperature have little an effect on heat capacity of air conditioner.Compared with the single operation condition,the heat capacity and COP of air conditioner stay the same,and the cooling capacity of freezer is higher under the combined operation of freezer and air conditioner.At the freezer temperature of-6°C,the cooling capacity of freezer increase by a maximum of 859 W.(4)The experiments in winter conditions found that the increase in the outdoor temperature reduces the COP of the freezer.When the mass flow ratio is less than 0.12,the increase in outdoor temperature lead to the reduce of cooling capacity of the freezer system.While in the range of mass flow ratio 0.12~0.2,the increased outdoor temperature raises the cooling capacity of freezer.The higher the outdoor temperature is,the greater the heat capacity and COP of air conditioner is.(5)The experimental results in winter conditions show that in the range of indoor temperature from 20°C to 24°C,the performance of the freezer system is nearly not affected by the indoor temperature.The heating capacity and the COP of the air conditioner system decrease,and the power consumption increase with the increase of indoor temperature.(6)The experimental results in summer conditions show that the cooling capacity and COP of the freezer system increase with the increase of the mass flow ratio,and the power consumption of the freezer is nearly unchanged.The power consumption and cooling capacity of the air conditioner system gradually decrease with the increase of the mass flow ratio.While the mass flow ratio has a little effect on the COP of the air conditioner system.(7)The experimental results in summer conditions show that the increase in freezer temperature can increase the cooling capacity and COP of the freezer,and it has the greatest impact at the freezer temperature of-6°C.The cooling capacity and power consumption of the air-conditioning system increase with the increase of freezer temperature.Compared with single operation,the cooling capacity of the freezer system is increased by approximately 300 W,and the COP is increased by approximately 0.3 under the combined operation of freezer and air conditioner.While the cooling capacity and the COP of the air-conditioning system are reduced.The maximum reduction of the cooling capacity is about 632 W under the freezer temperature of-12°C.(8)Experiments in summer conditions found that the increase in the outdoor temperature reduce the cooling capacity and COP of the air-conditioning system and the freezer system.When the mass flow ratio is 0.16,the outdoor temperature has the greatest impact on the refrigeration capacity and COP of the freezer.(9)Experiments in summer conditions found that the increase in the indoor temperature increase the refrigeration capacity and COP of the freezer system,and it is most obvious when the flow ratio is in the range of 0.04~0.08.The both of the cooling capacity and COP of air conditioner system increases with the increase of the indoor temperature,and the power consumption reduce with the increase of the indoor temperature.