NaCl溶液循环闪蒸的闪蒸速率实验研究
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摘要
闪蒸是许多工业过程的关键技术,对闪蒸强度的研究具有重要意义。本文定义循环闪蒸速率为停留时间内不平衡分数的平均变化率,代表了单位停留时间内消耗的过热能量,反映了循环闪蒸过程中闪蒸进行的真实强度。并设计搭建了循环闪蒸实验台,对NaCl溶液循环闪蒸的闪蒸速率进行了实验研究。研究发现,循环闪蒸的闪蒸速率随循环流量和平衡压力的增大而增大;随初始液膜厚度和浓度的增大而减小;随过热度增大,闪蒸速率先迅速减小,然后逐渐增大最终趋于平缓。
Flash vaporization is the key technology of lots of industrial processes.The research on the intensity of flash vaporization has great significance.In present paper,circulatory flash speed was defined as the average decreasing rate of non-equilibrium fraction during residence time inside flash chamber,which described the superheating energy consumed in unit time and represented the true intensity of circulatory flash vaporization.And an experimental rig for circulatory flash vaporization was designed and set up to carry out study on circulatory flash speed of NaCl solution circulatory flash.Results suggested that circulatory flash speed increased with the increasing of circulating flow rate and equilibrium pressure.Thicker water film and higher concentration of working fluids yielded smaller circulatory flash speed.Moreover,circulatory flash speed decreased rapidly at the initial stage,then increased with the increases of superheat degree and became flat eventually.
Flash vaporization is the key technology of lots of industrial processes.The research on the intensity of flash vaporization has great significance.In present paper,circulatory flash speed was defined as the average decreasing rate of non-equilibrium fraction during residence time inside flash chamber,which described the superheating energy consumed in unit time and represented the true intensity of circulatory flash vaporization.And an experimental rig for circulatory flash vaporization was designed and set up to carry out study on circulatory flash speed of NaCl solution circulatory flash.Results suggested that circulatory flash speed increased with the increasing of circulating flow rate and equilibrium pressure.Thicker water film and higher concentration of working fluids yielded smaller circulatory flash speed.Moreover,circulatory flash speed decreased rapidly at the initial stage,then increased with the increases of superheat degree and became flat eventually.
引文
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[12]Zhang D,Chong D T,Yan J J,et al.Study on SteamCarrying Effect in Static Flash Evaporation[J].International Journal of Heat and Mass Transfer,2012,55(17/18):4487-4497
[13]Zhang Y S,Wang J S,Liu J P,et al.Experimental Study on Heat Transfer Characteristics of Circulatory Flash Evaporation[J].International Journal of Heat and Mass Transfer,2013,67:836-842
[14]Tong L S,Tang Y S.Boiling Heat Transfer and Two-Phase Flow[M].Washington:Taylor&Francis,1997:7-9
[2]Venkatesan G,Iniyan S,Jalihal P.A Theoretical and Experimental Study of a Small-Scale Barometric Sealed Flash Evaporative Desalination System Using Low Grade Thermal Energy[J].Applied Thermal Engineering,2014,73(1):629-640
[3]Zotarelli M F,Porciuncula B D A,Laurindo J B.A Convective Multi-Flash Drying Process for Producing Dehydrated Crispy Fruits[J].Journal of Food Engineering,2012,108(4):523-531
[4]Li Y Z,Yan M,Zhang L Q,et al.Method of Flash Evaporation and Condensation-Heat Pump for Deep Cooling of Coal-Fired Power Plant Flue Gas:Latent Heat And Water Recovery[J].Applied Energy,2016,172:107-117
[5]Osamu M,Murakami K,Kawata Y,et al.Fundamental Experiments with Flash Evaporation[J].Heat TransferJapanese Research,1973,2(4):89-100
[6]Osamu M,Tetsu G,Toshiaki T,et al.Flash Evaporation Phenomena of Pool Water[J].Hear Transfer-Japanese Research,1977,6(2):13-24
[7]Gopalakrishna S,Purushothaman V M,Lior N.An Experimental Study of Flash Evaporation from Liquid Pools[J].Desalination,1987,65(1-3):139-451
[8]Saury D,Harmand S,Siroux M.Experimental Study of Flash Evaporation of a Water Film[J].International Journal of Heat and Mass Transfer,2002,45(16):3447-3457
[9]Fath H.The Non-Equilibrium Factor and the Flashing Evaporation Rate Inside the Flash Chamber of a Multistage Flash Desalination Plant[J].Desalination,1997,114(3):277-287
[10]Cipollina A,Micale G,Rizzuti L.Investigation of Flashing Phenomena in MSF Chambers[J].Desalination,2007,216(1-3):183-195
[11]Yan J J,Zhang D,Chong D T,et al.Experimental Study on Static/Circulatory Flash Evaporation[J].International Journal of Heat and Mass Transfer,2010,53(23):5528-5535
[12]Zhang D,Chong D T,Yan J J,et al.Study on SteamCarrying Effect in Static Flash Evaporation[J].International Journal of Heat and Mass Transfer,2012,55(17/18):4487-4497
[13]Zhang Y S,Wang J S,Liu J P,et al.Experimental Study on Heat Transfer Characteristics of Circulatory Flash Evaporation[J].International Journal of Heat and Mass Transfer,2013,67:836-842
[14]Tong L S,Tang Y S.Boiling Heat Transfer and Two-Phase Flow[M].Washington:Taylor&Francis,1997:7-9