Air-side heat transfer and pressure drop in accelerated flow evaporators.

Author(s) : WALTRICH P. J., BARBOSA J. R. Jr, MELO C., et al.


The performance of an alternative evaporator design for household applications, the so-called accelerated flow evaporator (AFE), is investigated in this paper. In this novel concept, the air-side cross sectional area decreases with the distance from the air flow inlet, accelerating the air as it flows across the tubes and, therefore, improving the airside local heat transfer coefficient. In principle, some geometrical configurations of the AFE are expected in which the heat transfer coefficient enhancement compensates the reduction of the heat exchanger surface for a given refrigeration capacity, thus reducing the material cost of the evaporator. Experiments have been conducted in an open-loop wind tunnel facility to determine the air-side heat transfer and pressure drop in nine AFE prototypes as a function of the air flow rate, the ratio of the outlet and inlet cross-section area and the number of fins. A calculation methodology has been proposed to correlate the air-side heat transfer and pressure drop in the AFE. The procedure relies on j and f factor correlations for plain fin-and-tube heat exchanger surfaces and on mass and momentum balances to determine the by-pass air stream through the clearance between the tube bank and the outer edge of the fins. The agreement between the model and the experiments is within plus or minus 10% for all heat transfer data and plus or minus 15% for the majority of the pressure drop data.

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  • Original title: Air-side heat transfer and pressure drop in accelerated flow evaporators.
  • Record ID : 2009-1679
  • Languages: English
  • Source: 2008 Purdue Conferences. 19th International Compressor Engineering Conference at Purdue & 12th International Refrigeration and Air-Conditioning Conference at Purdue [CD-ROM].
  • Publication date: 2008/07/14


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