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现行 RP-392
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Heat Transfer and Fluid Flow in a Finned Tube Flooded Evaporator 翅片管淹没式蒸发器内的传热和流体流动
本报告提供了根据ASHRAE RP-392完成的信息。该项目的目标是:1)使用几种不同的制冷剂和管道几何形状测量管束中的沸腾数据,以及2)开发用于预测数据的相关性。建立了一套实验装置,对热通量、蒸汽质量和质量速度进行独立控制,以模拟浸没式制冷剂蒸发器。报告了饱和温度为4.4 C和26.7 C时R-ll、R-123和R-134a的管束数据。管束呈交错排列,节径比为1.25。测试的管道包括格瓦- SE、Turbo-B和整体翅片管(26翅片/英寸)。数据涵盖的热通量为15至47 kW/m2,蒸汽质量为0.05至0.9,质量速度为8至26 kg/m2-s。数据包括对流蒸发和池沸腾。Turbo-B管未显示强制对流的影响。仅在低热通量下,对于R-ll和R-123数据,GEWA-SE管表现出强制对流效应。整体翅片管的R-ll数据显示了强制对流的强烈影响。这种效应在低热通量和4.4 C饱和温度下更为明显。提出了增强管的单位抑制因子。 Turbo-B管组上的R-ll和R-123数据,以及GEWA-SE管组上的R-134a数据支持该提案。使用“渐近”对流蒸发模型对数据进行关联。该模型考虑了核沸腾和对流蒸发的影响。渐近模型被提出为管和管组情况下的广义模型。对于整体翅片管,假设单位抑制因子。该模型将84%的数据关联在±20%范围内。
This report provides information done under ASHRAE RP-392. The project objectives were: 1) To measure data for boiling in tube bundles using several different refrigerants and tube geometries, and 2) To develop a correlation for prediction of the data. An experimental apparatus was built to provide independent control of heat flux, vapor quality and mass velocity in order to simulate flooded refrigerant evaporators. Tube bank data are reported for R-ll, R-123, and R-134a at saturation temperatures of 4.4 C and 26.7 C. The tube banks have staggered bundle layout and a pitch-to-diameter ratio of 1.25.The tubes tested include GEWA-SE, Turbo-B and integral finned tubes (26 fins/inch). The data span heat fluxes of 15 to 47 kW/m2, vapor qualities of 0.05 to 0.9, and mass velocities of 8 to 26 kg/m2-s. The data include both convective vaporization and pool boiling.The Turbo-B tubes show no effect of forced convection. The GEWA-SE tubes exhibit effect of forced convection only for the R-ll and R-123 data at low heat fluxes. The R-ll data on integral finned tubes show strong effects of forced convection. This effect is more pronounced at low heat fluxes and at 4.4 C saturation temperature. A suppression factor of unity is proposed for enhanced tubes. The R-ll and R-123 data on the Turbo-B tube bank, and the R-134a data on the GEWA-SE tube bank support this proposal.The data were correlated using an "asymptotic" convection vaporization model. This model accounts for the effect of nucleate boiling and convective evaporation. The asymptotic model is proposed as a generalized model for both, in-tube and tube bank situations. A suppression factor of unity is assumed for integral finned tubes. The model correlates 84% of the data within ±20%.
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