| Currently, perishable food accounted for fifty percent in the food structure of urban residential in China, while its comprehensive cold chain transportation rate was merely twenty percent, which could hardly meet the demand of the market. Thus, the increaserate on the performance of refrigerated truck’s refrigeration system became the vital problem for cold chain transportation industry to resolve. By the importation of ejector in refrigerated truck’s compression refrigeration cycle(CRC), coefficient of performance(COP) would be improved prominently. Meanwhile, fossil fuel consumption would also be relieved. Based on dual-evaporator compression-ejection compression cycle(CERC), results achieved in this thesis were follows:1. Thermodynamic analysis was performed on the throttling losses in two types of conventional CRC, the results showed(1) throttling loss versus power consumption of the compressor in serial CRC was 0.9 to 3.9 percent higher than that of the parallel CRC and COP increaserate was 6.5 to 17 percent higher when throttling losses were recovered.(2) When the high evaporating temperature or load ratio of the two evaporators were higher, COP increaserate in both CRCs went higher; while the increase of low evaporating temperature or condensing temperature would led to the opposite effect.2. Three commonly adopted throttling loss recovery scheme were studied in this paper, and the scheme of replacing the expansion valve with ejector was calculated by Matlab. Simulation results showed(1) the ejector replacement scheme got a 7.7 to 51.5 percent COP increaserate;(2) when load ratio of the two evaporators was higher than 1, the ejector replacement scheme showed a higher COP increaserate than the throttling loss totally recovery scheme.3. Performance of six types of CERCs was compared and studied under various operating parameters. The results showed(1) COP of serial single–phase CER was 0.11 to 0.15 higher than that of the parallel single-phase CERC, while the ejector coefficient is 0.151 to 1.157 lower;(2) COP of parallel double–phase CER was 0.52 to 0.78 higher than that of the serial single-phase CERC, and the high evaporating temperature was 3.29 to 4.42 degree Celsius higher, while the ejector coefficient was 0.017 to 1.4 lower;(3) COP of the parallel single-double–phase CER was 0.78 to 2.12 higher than that of the serial single-double-phase CERC; When the load ratio of two evaporators was equal, ejector coefficient of the double-phase ejector was higher than that of the single-phase ejector.4. A new type of dual-evaporator CERC was presented and studied. Together with other three CERCs, the new CERC was compared with CRC under various testing parameters, the results showd that the sequence of COP increaserate of testing CERCs was serial single-double CERC(97.6 percent), parallel double-phase CERC(49.3 percent), serial single-phase CERC(30.9 percent) and the new CERC(2.46 percent).5. Based on the research of ejector design methods, both the single-phase ejector and the double-phase ejector was designed with actual operating parameters of dual-evaporator refrigerated truck. Moreover, the calculation program of ejector was composited by Visual Basic. At last, the reliability of numerical simulation was vertified. Experimental scheme of two types of CERCs was designed and relevent analysis was given. |
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