LNG汽车冷能回收系统相似模化分析

在相似理论的指导下，通过对比分析氮气和天然气的物性，对液氮模拟液化天然气汽车冷能回收系统进行了相似模化分析。结果表明，在LNG冷能回收系统各换热器中，表征氮气与天然气流动与换热的主要准则--雷诺数准则和普朗特数准则非常接近，二者偏差均在保持在5％以内。在此基础上建立的试验系统测试结果表明，液氮模拟LNG冷量回收汽车空调系统具有较好的冷量利用性能。氮气流量在5.5～8.5 m³/h范围内，系统回收冷量满足汽车空调送风温度要求。因而，作为研究的一个重要步骤，可以采用安全、便宜的液氮替代液化天然气，进行系统冷能回收实验研究。

SIMILAR MODELING ANALYSIS OF COLD ENERGY RECOVERY SYSTEM OF LNG VEHICLES

Natural gas is a flammable and explosive material. It needs better experimental conditions and safe environment to carry out the lab test on the LNG cold energy recovery. The property of nitrogen and natural gas are compared and analyzed. Based on the theory of similarity, similar modeling analysis of the liquid nitrogen simulative cold energy recovery system of LNG is conducted. The results show that the rule of Re and Pr, the main rules to express flowing and heat exchanging, are approximately equal to each other, with the relative deviation of within 5%. An experimental system simulating cold energy recovery of LNG with liquid nitrogen is established based on the anterior analysis. The measurement result indicates that the system has perfect performance with the nitrogen flow about 5.5-8.5 . The cold energy recovered satisfies the cold air temperature requirement of the vehicle air conditions. As the important step of study, nitrogen can be used to replace LNG as the safe and cheap experimental material in cold energy recovery study.