Experimentation on Air Leakage Characteristics and Key Paremeters Analysis of Refrigerated Transport Unit

At present,the test index of air leakage is not uniform in different standards in China.Constant pressure difference method and tracer gas concentration decay method were used to test air tightness characteristic of refrigerated transport unit. The variations of air leakage were tested under conditions of different pressures( 50 Pa,100 Pa,150 Pa,200 Pa and 250 Pa),different velocities( 20 km/h,40 km/h,60 km/h,80 km/h and 100 km/h) and different agings( 0,71 000 km,126 000 km and 175 000 km). The matching relationship between different parameters was analyzed. The research gave determined method of air leakage characteristic curve with experimentation and empirical formula.The test method was recommended in practical application. It showed that the leakage rate was influenced by air tightness and velocity,and the influence of aging was great. There was a maximum of 20 times difference of air leakage index in GB 29753,GB/T 5600 and GB/T 7392. Test pressures of 50 Pa,100 Pa and 250 Pa were corresponded to velocities of 30 ~ 40 km/h,45 ~ 60 km/h and 70 ~ 100 km/h.And the air leakage was about 1 ∶ 2 ∶ 4 under the conditions of above constant pressure difference. After driving 100 000 km and 200 000 km,the air leakage of refrigerated transport unit was increased by 40%and 110% under 250 Pa pressure difference. Combined with the actual situation,it was suggested that 250 Pa as the uniform constant pressure difference condition for air leakage test standard,and a system should be established to regularly check the thermal performance of refrigerated transport unit. In addition,the air leakage of refrigerated transport unit was influenced by internal partition form,goods stacking form, temperature, etc. A comprehensive and thorough analysis was needed in the later research.

This article is in Chinese.