The effect of circuiting arrangement on the thermal performance of refrigerant mixtures in tube-and-fin condensing heat exchangers
For the pure or azeotropic refrigerants typically used in present air conditioning and refrigeration applications, the refrigerant changes phase at a constant temperature. Thus, the refrigerant circuiting arrangement such as crossflow, counterflow, or cross-counterflow, has no effect on the thermal performance. For zeotropic refrigerant mixtures, however, the phase-change occurs over a temperature range, or glide, and the refrigerant circuiting arrangement, or flow path through the heat exchanger, can affect the thermal performance of both the heat exchangers as well as the overall efficiency of the vapor compression cooling cycle. The effects of two different circuiting arrangements on the thermal performance of a zeotropic refrigerant mixture and an almost azeotropic refrigerant mixture and an almost azeotropic refrigerant mixture in a four-row cross-counterflow heat exchanger arrangement are reported here. The two condensers differ only in the manner of circuiting the refrigerant tubes, where one has refrigerant always flowing downward in the active heat transfer region (identical order) and the other has refrigerant alternating flow direction in the active heat transfer region (inverted order). All other geometric parameters, such as face area, fin louver geometry, refrigerant tube size and enhancement, etc., are the same for both heat exchangers. One refrigerant mixture (R-410A) undergoes a small temperature change (low glide) during phase change, and the other refrigerant mixture (a multi-component proprietary mixture) has a substantial temperature change (high glide) of approximately 10 C during the phase change process. The overall thermal conductance, two-phase conductance, and pressure drop are presented. For the flow conditions of these tests, which are representative of residential cooling conditions, inverted order circuiting is more desirable than identical order. The potential thermal advantages of the identical order arrangement for high-glide zeotropic refrigerant mixtures are negated by the increased parasitic refrigerant-side pressure drop unfortunately resulting from fabrication requirements of the identical order circuiting.
- Research Organization:
- Oak Ridge National Lab., TN (US)
- OSTI ID:
- 20030447
- 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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