Evaporating Heat Transfer Characteristics of R-l34a in a Horizontal Smooth Channel

  • Pamitran, A.S. (Graduate School, Department of Refrigeration Engineering, Chonnam National University) ;
  • Choi, Kwang-Il (Graduate School, Department of Refrigeration Engineering, Chonnam National University) ;
  • Oh, Jong-Taek (Department of Refrigeration Engineering, Chonnam National University) ;
  • Oh, Hoo-Kyu (Department of Refrigeration and A/C Engineering, Pukyong National University)
  • Published : 2006.12.10


Convective boiling heat transfer coefficients were measured in a horizontal minichannel with R-l34a. The test section was made of stainless steel tube with an inner diameter of 3.0 mm and a length of 2m. It was uniformly heated by applying electric current directly to the tube. Local heat transfer coefficients were obtained for heat fluxes from 10 to $40kW/m^2$, mass fluxes from 200 to $600kgT/m^2s$, qualities up to 1.0, and the inlet saturation temperature of $10^{\circ}C$. The experimental results were mapped on Wojtan et $al.'s^(7)$ and Wang et $al.'s^(8)$ flow pattern maps. The nucleate boiling was predominant at low vapor quality whereas the convective boiling was predominant at high vapor quality. Laminar flow appeared in the flow with minichannel. The experimental results were compared with six existing two-phase heat transfer coefficient correlations. A new boiling heat transfer coefficient correlation based on the superposition model for refrigerants was developed with mean and average deviations of 10.39% and -3.66%, respectively.



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