供液方式对蒸发平板温度场的影响
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摘要
研究相同工况下平板速冻机不同供液方式的温度场分布,分析造成平板冻结速率不均的原因。分别进行冷凝温度为35℃时射流泵和膨胀阀供液的速冻试验。结果表明:冻结结束时,使用膨胀阀供液冻品最低温度达到-35.9℃,冻品最大温差17.55℃,各层平板温差都较大,平板温度分布较为混乱;射流泵供液时,冻品的温度各层分布均匀,冻结结束时所有冻品最大温差5.54℃,同时各层冻品的温差由上至下逐渐减小,平板冻结速率逐渐增加,其中最底层平板冻结时间比最上层约短9.1%。证明蒸发平板的温度分布对系统冻结时间和能耗有影响。
This paper studied the temperature distribution of different mode of liquid supply in plate freezer under the same working condition,and analyzed the reasons for the inequality freezing rate of the flat plate.The freezing experiment of the fluid supply with ejector and the expansion valve at the same condense temperature in 35 ℃was carried out respectively.The results showed that:at the end of freezing,the minimum temperature reached to-35.9 ℃ by using expansion valve,and the maximum temperature difference of frozen products was 17.55 ℃.The temperature difference of each layer was large,and the temperature distribution of plate was chaotic.In mode of ejector supplying liquid,frozen temperature distribution was uniform,the maximum temperature difference was 5.54℃at the end of experiment.Meanwhile,each layer plate of temperature decreases gradually from top to bottom,freezing rate increases gradually,and the bottom plate freezing time was shorter than the top about 9.1%.To a certain extent,this study can prove the effect of the temperature difference distribution of the evaporated plate on the freezing time and energy consumption.
This paper studied the temperature distribution of different mode of liquid supply in plate freezer under the same working condition,and analyzed the reasons for the inequality freezing rate of the flat plate.The freezing experiment of the fluid supply with ejector and the expansion valve at the same condense temperature in 35 ℃was carried out respectively.The results showed that:at the end of freezing,the minimum temperature reached to-35.9 ℃ by using expansion valve,and the maximum temperature difference of frozen products was 17.55 ℃.The temperature difference of each layer was large,and the temperature distribution of plate was chaotic.In mode of ejector supplying liquid,frozen temperature distribution was uniform,the maximum temperature difference was 5.54℃at the end of experiment.Meanwhile,each layer plate of temperature decreases gradually from top to bottom,freezing rate increases gradually,and the bottom plate freezing time was shorter than the top about 9.1%.To a certain extent,this study can prove the effect of the temperature difference distribution of the evaporated plate on the freezing time and energy consumption.
引文
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[2]杜子峥,谢晶.冷库节能减排研究进展[J].食品与机械,2014,30(1):4-11.
[3]陈依水.引射泵在平板速冻机制冷系统中的应用[J].渔业现代化,1990(4):19-21.
[4]李丽芬.热力膨胀阀选型方法研究及对系统可靠性的影响[D].上海:上海交通大学,2008:2-4.
[5]张剑萍.制冷的基本装置——“膨胀阀”(上)[J].商场现代化,1981(4):18-22.
[6]LORENTZEN G.Throttling,the internal haemorrhage of the refrigeration process[C]//The Plenary Session of the 16th IIR Congress.Paris:Proceedings of the Institute of Refrigeration,1983:39-47.
[7]张棣,董祥伟,李增亮,等.射流泵内流场数值计算的结构化网格划分方法[J].石油矿场机械,2016,42(11):1-7.
[8]DOPAZO J A,FERNNDEZ-SEARA J,SIERES J,et al.Theoretical analysis of a CO2-NH3,cascade refrigeration system for cooling applications at low temperatures[J].Applied Thermal Engineering,2009,29(8):1 577-1 583.
[9]LAWRENCE N,ELBEL S.Experimental investigation of a twophase ejector cycle suitable for use with low-pressure refrigerants R134aand R1234yf[J].International Journal of Refrigeration,2014,38(1):310-322.
[10]JEON Y,KIM S,KIM D,et al.Performance characteristics of an R600ahousehold refrigeration cycle with a modified twophase ejector for various ejector geometries and operating conditions[J].Applied Energy,2017,205:1 059-1 067.
[11]肖颀,林原胜,魏志国,等.射流泵内压力分布研究[J].舰船科学技术,2017,39(1):85-89.
[12]田晓雨,万金庆,曹晓程,等.冷凝温度变化对两相射流泵供液平板速冻机的影响[J].食品与机械,2016,32(11):71-73.
[13]ARUN K M,TIWARI S,MANI A.Three-dimensional numerical investigations on rectangular cross-section ejector[J].International Journal of Thermal Sciences,2017,122:257-265.
[14]万金庆,宋立尧,曹晓程,等.一种射流泵节流供液制冷系统:中国,102878715B[P].2013-01-16.