Experimental Study On Performance Of The Air Cooler In Refrigeration Device

Air cooler is commonly used in refrigeration unit as refrigeration equipment, which is acombination of copper aluminum fin evaporator and axial fans. Over the years, Air coolerrelevant performance parameters used in the selection reference air cooler test data ofsimilar foreign products and play a discount. Since the reform and opening up, especially inrecent years, air cooler production enterprises in our country have gained rapiddevelopment, design and production and processing level have been greatly improved.However, the engineering application enterprise and the production and processingenterprises know little about the actual performance of the domestic air cooler, whichlargely affect the air cooler heat transfer performance and technical innovation, different aircoolers have different technical performance parameters and heat transfer effects, and thestand or fall of air cooler heat transfer performance directly affect the cooling effect of thewhole refrigeration system. Therefore, the study of the actual performance of the domesticair cooler and its influencing factors, quantitative grasp the actual refrigerating capacity andheat transfer coefficient, which is of great significance for the production, processing andpractical application of air coolers.Now, the domestic consumption of copper and aluminum made into air coolers is quitelarge, which is a large proportion in the metal consumption and the cost of the cold storagesystem. Propelling air cooler’s heat transfer performance research as soon as possible andsetting up perfect air cooler performance database, not only can improve the performanceand efficiency of air cooler, but also can reduce the energy consumption of the air cooler toachieve the purpose of energy conservation and emissions reduction. Therefore, theperformance study of air cooer is an important research topic in the refrigeration technologyapplication field.In summary, we built the air cooler performance testing laboratory in line with nationalstandards GB/T25129-2010and SB/T10795-2012, and established the mathematicalmodel of air coolers. Ten different air coolers are studied in this paper. The refrigeratingcapacity of these air coolers are tested out using heat balance method andenthalpy-difference method at the calibrating tank temperature4℃,0℃,-4℃,-8℃,-12℃,-16℃and-20℃.The cooling capacity, heat transfer coefficient, supply andreturn air temperature difference and other thermotechnical parameters of air cooler changecurves are drawn with experimental data in different conditions, and the primary factorsaffecting the heat-transfer performance of air cooler are analyzed; theoretical andexperimental values of air cooler heat transfer coefficient are comparatively studied, and we analyze the reasons for differences between the theoretical and experimental values; westudy the effect of fan and compressor frequency conversion on the performance of aircoolers, and the reasons of differences in heat transfer coefficient are summed up from aircooler power consumption, unit heat transfer area with air flow, the level of productiontechnology and the structure of air coolers, etc, which provides basis to further improve thelevel of air cooler design, production and processing.The results show that the laboratory has a high testing precision, the error of therefrigerating capacity testing results using the two methods are less than5%; the error ofthe heat transfer coefficient of theoretical calculations and experiment is70%, numericalcalculation can study the tendency of the heat transfer coefficient of air cooler, but if wewant to get the accurate value of heat transfer coefficient we have to make experimentalstudy; the error rates of air cooler NO.1-4nominal refrigerating capacity compared toactual refrigerating capacity are:23.8%,22.9%,28.5%and30%,the actual refrigeratingcapacity have not reached the nominal refrigerating capacity; the heat transfer coefficient ofevaporation tube staggered arrangement air cooler is29.4%larger than cis-rowarrangement air coolers, refrigerating capacity6.2%larger; the heat transfer coefficient ofinner grooved copper tube air cooler is18.65%larger than the smooth tube air cooler,refrigerating capacity12.4%larger; different air cooler has different heat transferperformance, NO.7air cooler has the largest average heat transfer coefficient of34.0w/(m2k), NO.3minimum10.6w/(m2k); the air volume of internal thread tube air coolerper unit heat exchanger area is about205m3/h, the air volume of smooth tube air cooler perunit heat transfer area is about186m3/h, and the supply and return air temperaturedifference in the range of2.55℃and4.11℃changing,the air cooler has better heattransfer performance. Fan frequency from30Hz to60Hz, the heat transfer coefficientincreased by31.5%, the supply and return air temperature difference dropped from5.15℃to3.1℃, air cooler has a maximum cooling capacity of6.031kw, air cooler fan power andair volume exist a configured best point.