Spray evaporation heat transfer of R-134A on plain tubes
- Iowa State Univ., Ames, IA (United States). Dept. of Mechanical Engineering
A test facility for performing spray evaporation tests was constructed and results are reported for refrigerant R-134a with horizontal, plain-surface, copper alloy tubes. In addition, the effects of nozzle type, liquid feed rate, and tube diameter on heat transfer coefficients are demonstrated. Pool boiling experiments were also performed and a comparison was made with spray evaporation results under similar conditions. The test tubes used in this study were 12.7 mm (1/2 in.) and 19.1 mm (3/4 in.) diameter copper tubes that were electrically heated by using inserted cartridge heaters. Average heat transfer coefficients were calculated by measuring the average surface temperature with wall-mounted thermocouples and the vapor space temperature with thermocouple probes. The 12.7 mm (1/2 in.) diameter tubes performed better than the 19.1 mm (3/4 in.) tubes, and the heat transfer performance was significant in, affected by the liquid feed rate once dry-out effects became dominant. For the range of liquid feed rates evaluated, the heat transfer performance for spray evaporation was greater than the pool boiling performance at low heat fluxes and less at the higher heat fluxes.
- OSTI ID:
- 33244
- Report Number(s):
- CONF-9406105--
- Country of Publication:
- United States
- Language:
- English
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