The effect of heating direction on flow boiling heat transfer of R134a in micro-channels

2017 ◽  
Vol 26 (2) ◽  
pp. 166-174 ◽  
Author(s):  
Mingchen Xu ◽  
Li Jia ◽  
Chao Dang ◽  
Qi Peng
Keyword(s):  
Heat Transfer ◽  
Boiling Heat Transfer ◽  
Flow Boiling ◽  
Flow Boiling Heat Transfer ◽  
Micro Channels ◽  
Heating Direction

Proposed Correlation for Forced Convection Boiling Heat Transfer in Mini and Micro Channels With CO2 as a Fluid

2014 ◽  
Author(s):  
Mayank I. Vyas ◽  
Salim A. Channiwala ◽  
Mitesh N. Prajapati
Keyword(s):  
Heat Transfer ◽  
Boiling Heat Transfer ◽  
Two Phase Flow ◽  
Flow Boiling ◽  
Nucleate Boiling ◽  
Working Fluid ◽  
Phase Flow ◽  
Two Phase ◽  
Flow Boiling Heat Transfer ◽  
Micro Channels

After reviewing the available literature on flow boiling heat transfer in mini/micro tubes and channels, it is felt that there is need for predictive correlations which is applicable over wide range of parameters. In present work a new correlation for two-phase flow boiling heat transfer coefficient is developed, which has considered nucleate boiling and convective boiling heat transfer effect. To develop this correlation we have considered total 651 data points, which have been collected from the open available literature covering different operational conditions and different dimensions of channels. We have selected CO2 as a working fluid because it does not contain chlorine, hence an efficient and environmentally safe refrigerant and would be potential replacement for R-22. CO2 has unusual heat transfer and two-phase flow characteristics, and is very different from those of conventional refrigerant. Also a comparison of present correlation with the best published correlation for CO2 is done. The results of this comparison indicate that the new developed correlation is superior to published best correlation for CO2. Present correlation is also compared with best published correlation for all fluids and with the correlation developed by using CO2 data. The results of these both case, indicate that the present correlation is superior.

Flow Boiling Heat Transfer of R123/R134a Mixture in a Micro-Channel

2010 ◽  
Author(s):  
Sehwan In ◽  
Sangkwon Jeong
Keyword(s):  
Heat Transfer ◽  
Boiling Heat Transfer ◽  
Flow Boiling ◽  
Micro Channel ◽  
Heat Transfer Characteristics ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Transfer Characteristics ◽  
Flow Boiling Heat Transfer ◽  
Micro Channels

This paper describes the flow boiling heat transfer of R123/R134a mixture in a single round micro-channel with 0.19 mm ID. The flow boiling heat transfer coefficients were measured with the variation of mixture composition (R123 mole fraction: 0.502, 0.746) at various experimental conditions: mass velocities (314, 392, 470 kg/m2-s), heat fluxes (10, 15, 20 kW/m2) and vapor qualities (0.2–0.85). The heat transfer characteristics of R123/R134a mixture are similar to those of pure R123 observed in the previous flow boiling experiment. The similarity of heat transfer characteristics denotes that the heat transfer is governed by evaporation of thin liquid film around the elongated bubbles like the case of pure R123. The heat transfer coefficients of R123/R134a mixture are compared with those of equivalent pure refrigerant by the correlation developed from pure R123 experimental results. The large reduction of heat transfer coefficients compared with pure refrigerant is found in micro-channels flow boiling by the mass transfer effect of mixed refrigerant. In addition, macro-channel correlations for mixed refrigerant do not make accurate prediction about the reduction of heat transfer coefficients.

Two-phase flow boiling heat transfer of FC-72 in parallel micro-channels

2017 ◽  
Vol 30 (4) ◽  
pp. 284-301 ◽  
Author(s):  
Yong-Seok Choi ◽  
Tae-Woo Lim ◽  
Sam-Sang You ◽  
Hwan-Seong Kim
Keyword(s):  
Heat Transfer ◽  
Boiling Heat Transfer ◽  
Two Phase Flow ◽  
Flow Boiling ◽  
Phase Flow ◽  
Two Phase ◽  
Flow Boiling Heat Transfer ◽  
Micro Channels
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