Study Of Microchannel Heat-exchanger In Domestic Refrigerator And Air Side Dust Fouling

In 2017,only new domestic refrigerators have a 40% efficiency increase,they can meet the 1st class energy comsunption standard based on the requirement of nation standard Power consumption limit and energy efficiency of household refrigerators(GB 12021.2-2015).According to this situation China are carring out research about performance improvement in domestic refrigerator.Tube and wire condenser are wide applied in domestic refrigerator in China now,because of the increasing energy consumption requirement,traditional heat exchanger can not meet the new demand,however developing next generation heat exchanger are facing with several challenges,such as:1.most of existing studies focused on modifying of traditional heat exchanger,there are not many research about innovation in heat exchanger.2.the domestic appliance industry is very sensitive to the cost,the manufacturing cost of new type heat exchanger should be controlled in an appropriately method.3.how to improve the efficiency of refrigeration cycle after the replacing of heat exchanger.4.how to solve the dust clogging problem on the condenser surface due to Chinese air pollution.Aiming to solve problem above mentioned,the main tasks and results of this article are:1.This thesis established a methmatical model of microchannel condenser firstly,several heat exchanger samples were designed and manufactured based on this model,then traditional heat exchanger and microchannel heat exchangers were compared in heat exchanger test,according to the test results,optimal designed microchannel heat exchanger(MCHX)can have a 13% increase in heat transfer performance,air side pressure drop of MCHX is only 28% of traditional one,refrigerant side pressure drop is only 54% of original design.According to the performance test results,MCHX can be good replacement to traditional heat exchanger in domestic refrigerator,it’s volume is only 20% of the original,it’s weight is only 35% and manufacturing cost is only 50%.2.Based on the model analysis and heat exchanger test results,a MCHX was applied into the refrigerator,refrigeration system performance and unit perfaomance were studied.This thesis studied system performance under different refrigerant charge amount,superheat degree of evaporator and compressor speed.After the application of MCHX,under the optimal charge amount,the refrigeration capacity was increased by 16.7%,the compressor energy consumption remained unchanged and COP was increased by 15.4% compared with the original system.Refrigerator unit enegy consumption was tested according to the requirement of new Chinese standard GB/T8059,using MCHX,the unit enegy consumption was decreased by 2.6% and it can reach to 1st class energy consumption standard.3.This thesis detailed studied air side dust pollution of MCHX in domestic refrigerator,dust pollution problem was analysised through family application test firstly,then different MCHX were tested under the same polluted condition,heat exchanger performance damping degree of plain fin and louver fin MCHX with different fin pitches were compared.Finally,dust fouling process and fouling mechanism were studied,this thesis gave a detailed description of three stages in fouling process,fouling phenomena and damping degree of different fouling stage.