Characteristics of Heat Transfer and Pressure Drop of R-22 Inside an Evaporating Tube with Small Diameter Helical Coil

Title & Authors
Characteristics of Heat Transfer and Pressure Drop of R-22 Inside an Evaporating Tube with Small Diameter Helical Coil
Kim, Ju-Won; Kim, Jeong-Hun; Seo, Seok-Ki; Kim, Jeung-Hoon; Kim, Jong-Soo;

Abstract
To make compact evaporator, experiments that show characteristics of evaporating heat transfer and pressure drop in the helically coiled small diameter tube were taken in this research. The experiments were performed with HCFC-22 in the helically coiled small diameter tube; inner diameter=1.0(mm), tube length=2.0(m), and curvature diameter=31, 34, 46.2(mm). The experiments were also carried out with the following test conditions; saturation pressure=0.588(MPa), mass velocity=$\small{150{\sim}500(kg/m^2s)}$, and heat flux=$\small{1{\sim}5(kW/m^2)}$. The experiment results are that the empirical correlation to predict heat transfer coefficient for single phase flow in helically coiled small diameter tube was obtained. It was found that dry-out is occurred at low-quality region for evaporation heat transfer because of breaking of annular liquid film. The friction factor of single phase flow of helically coiled tube was agreed with Prandtl's correlation. Finally, It was proposed for correlation that can precisely predict the friction factor of two phase flow of helically coiled tube
Keywords
Heat Transfer Coefficient;Pressure Drop;Helically Coiled Tube;Compact Heat Exchanger;Dean Number;Small Diameter Tube;Secondary Flow;
Language
Korean
Cited by
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