Heat transfer of liquid refrigerant R-134a cooled in small circular tubes
Owing to the micro-fabrication technology development of integrated circuits, smaller tubes can be made and used for increasing the compactness of heat exchangers. However, the traditional heat transfer correlations are derived from tubes diameter much larger than those used in micro-channels. They have not been verified to work well for predicting the heat transfer coefficient inside small hydraulic diameter tubes. Several researches dealing with the single-phase heat transfer inside small tubes have been published in the past few years. Most of their test results show that the friction factors are in relatively good agreement with the Moody chart. However, the existing literatures show a considerable disagreement as to the effect of small channel size on heat transfer coefficients. This manuscript provides an experimental study of heat transfer for liquid refrigerant R-134a cooled in three small circular tubes with diameters 0.8, 1.1 and 1.4 mm. Data are presented at temperature 50 C and Reynolds number from 3,000 to 20,000. The experimental results show that the tested data are approximately 18% higher than those predicted by Petukhov equation. If the authors replace the friction factor terms in the Petukhov equation by the measured values, the predicted heat transfer coefficients agree well with the experimental values for those three tubes.
- Research Organization:
- National Central Univ., Chung-Li (TW)
- OSTI ID:
- 20030491
- Resource Relation:
- Conference: 5th ASME/JSME Thermal Engineering Joint Conference, San Diego, CA (US), 03/14/1999--03/19/1999; Other Information: 1 CD-ROM. Operating system required: Windows i386(tm), i486(tm), Pentium (R) or Pentium Pro, MS Windows 3.1, 95, or NT 3.51, 8 MB RAM, MacIntosh and Power MacIntosh with a 68020 or greater processor, System software version 7.1, 3.5 MB RAM (5 MB for PowerMac) 6 MB available hard-disk space, Unix; PBD: 1999; Related Information: In: Proceedings of the 5th ASME/JSME thermal engineering joint conference, [3600] pages.
- Country of Publication:
- United States
- Language:
- English
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