冷藏运输工具渗风特性试验与关键参数分析

Experiment on Air Leakage Characteristics and Key Parameters Analysis of Refrigerated Transport Unit

针对目前国家标准中不同冷藏运输工具渗风量检测指标不统一的问题,运用静态压差法和示踪气体浓度衰减法对不同气密性条件的冷藏车展开试验,分析不同速度、不同压差、不同老化程度条件下渗风量变化规律,寻求之间的匹配关系,为相关标准的制定提供依据。研究给出了静压条件下冷藏运输工具渗风特性曲线的试验确定法和经验公式确定法,认为渗风量受工具本身气密性和速度的双重影响,且工具老化对渗风影响较大。分析表明现行铁路冷藏车、公路冷藏车和冷藏集装箱在标准测定条件下,渗风要求最大存在20倍的差距;50、100、250 Pa的测试压差分别对应30～40 km/h、45～60 km/h、70～100 km/h的运行速度,渗风量约为1∶2∶4的关系;在老化率方面,250 Pa压差条件下车辆行驶10万km和20万km后,车厢渗风量分别上升40%和110%。结合实际情况,建议将250 Pa静压差作为冷藏运输工具渗风量检测的统一测试基准值,并建立热工性能定期校验制度。

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 that250 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.