In the present study, the characteristics of heat transfer and flow patterns are experimentally investigated on the falling film evaporation of pure refrigerant HCFC123 in a vertical rectangular minichannel consisting of offset strop fins. The refrigerant liquid is supplied to the channel through 37 holes of a distributor. The liquid flowing down vertically is heated electrically from the rear wall of the channel and evaporated. To observe the flow patterns during the evaporation process directly, a transparent vinyl chloride resin plate is placed as the front wall. The experimental parameters are as follows: the mass velocity G = 28∼70 kg/(m2s), the heat flux q = 20∼50 kW/m2 and the pressure P≈ 100 kPa. It is clarified that the heat transfer coefficient α depends on G and q in the region of vapor quality x ≥ 0.3 while there is little influence of G and q in the region x ≤ 0.3. From the direct observation using a high speed video camera and a digital still camera, flow patterns are classified into five typical ones: plane liquid film, wavy liquid film, liquid film accompanied with dry patch, liquid film accompanied with dripping and liquid film accompanied with mist. Then the relation between heat transfer and flow pattern is clarified. The results of heat transfer characteristics are also compared with some previous correlation equations.
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ASME 3rd International Conference on Microchannels and Minichannels
June 13–15, 2005
Toronto, Ontario, Canada
Conference Sponsors:
- Nanotechnology Institute
ISBN:
0-7918-4185-5
PROCEEDINGS PAPER
Falling Film Evaporation of Pure Refrigerant HCFC123 in a Vertical Rectangular Minichannel Consisting of Offset Strip Fins Available to Purchase
Junichi Ohara,
Junichi Ohara
Numazu College of Technology, Numazu, Shizuoka, Japan
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Shigeru Koyama,
Shigeru Koyama
Kyushu University, Kasuga, Fukuoka, Japan
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Ken Kuwahara
Ken Kuwahara
Kyushu University, Kasuga, Fukuoka, Japan
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Junichi Ohara
Numazu College of Technology, Numazu, Shizuoka, Japan
Shigeru Koyama
Kyushu University, Kasuga, Fukuoka, Japan
Ken Kuwahara
Kyushu University, Kasuga, Fukuoka, Japan
Paper No:
ICMM2005-75128, pp. 49-56; 8 pages
Published Online:
November 11, 2008
Citation
Ohara, J, Koyama, S, & Kuwahara, K. "Falling Film Evaporation of Pure Refrigerant HCFC123 in a Vertical Rectangular Minichannel Consisting of Offset Strip Fins." Proceedings of the ASME 3rd International Conference on Microchannels and Minichannels. ASME 3rd International Conference on Microchannels and Minichannels, Part B cont’d. Toronto, Ontario, Canada. June 13–15, 2005. pp. 49-56. ASME. https://doi.org/10.1115/ICMM2005-75128
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