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A study on the friction head loss in flat aluminum micro multi tubes with nonazeotropic refrigerant mixtures R-410A  

Lee, Jeong-Kun (Korea Energy Engineers Association)
Min, Kyung-Ho (Department of Mechanical System, Incheon Campus of Korea Polytechnic)
Publication Information
Design & Manufacturing / v.13, no.2, 2019 , pp. 37-43 More about this Journal
Abstract
This study conducted a research as to condensation heat transfer friction loss headby using three types of flat micro multi-channel tubes with different processing of micro-fin and number of channels inside the pipes and different sizes of appearances. In addition, identical studies were conducted by using smoothing circular tubes with 5mm external diameter to study heat enhancement factor and pressure drop penalty factor. 1) The friction head loss showed an increase as the vapor quality and mass flux increased. In case of saturation temperature, it shows an increase as it gets lower. These factors are the reason occurring as the lower the saturation temperature is, the higher the density of refrigerant vapor gets. The influence of heat flux is similar as the dryness is low, but as it gets higher, it lowers in heat flux, and as the high temperature of high heat flux, it is a factor that occurs as the density gets lower. 2) RMS error of the in case of friction head loss, it showed to be predicted as 0.45~0.67 by Chisholm, Friedel, Lockhart and Martinelli. 3) As forfriction head loss penalty factor, the smaller the aspect ratio is, the larger the penalty factor gets, and as for the effect of micro-fin, the penalty factor increased because it decreases to the gas fluid the way groove for the refrigerant's flow.
Keywords
Condenser; Head Loss; Micro Multi Tube; Pressure Drop; R-410A;
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