Condensing Heat Transfer Characteristics of HFC-134a and CFC-12 Inside a Smooth Tube in Low Mass Velocity Range
Abstract
Condensing heat transfer coefficients of HFC-134a and CFC-12 were measured inside a horizontal and a vertical smooth tub with an inner diameter of 4.35mm. The mass velocity of refrigerant ranged from 60 to 170 kg/(m2s) and the saturation temperature was about 450°C.
The results obtained are as follows ; (1) According to the difference in flow directions, condensing heat transfer coefficients in low mass velocity range (below 100 kg / (m2s)) were ranked as follows ; horizontal›vertical upward›vertical downward. (2) Condensing heat transfer coefficient of HFC-134a was 15-20% higher than that of CFC-12 with both horizontal and vertical tubes.- Publication:
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Transactions of the Japan Society of Refrigerating and Air Conditioning Engineers
- Pub Date:
- 2011
- Bibcode:
- 2011TRACE..11..329I
- Keywords:
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- Condensation;
- Heat transfer;
- HFC-134a;
- CFC-12;
- Experiment;
- Vertical tube;
- Upward flow;
- Downward flow;
- Horizontal tube