Research Papers

Heat Exchanger Design of Direct Evaporative Cooler Based on Outdoor and Indoor Environmental Conditions

[+] Author and Article Information
Neda Gilani

Fouman Faculty of Engineering,
College of Engineering,
University of Tehran,
P.O. Box 43515-1155,
Fouman 43516-66456, Iran
e-mail: gilani@ut.ac.ir

Amin Haghighi Poshtiri

Department of Mechanical Engineering,
University of Guilan,
P.O. Box 3756,
Rasht, Iran

1Corresponding author.

Contributed by the Heat Transfer Division of ASME for publication in the JOURNAL OF THERMAL SCIENCE AND ENGINEERING APPLICATIONS. Manuscript received May 3, 2014; final manuscript received July 21, 2014; published online August 26, 2014. Assoc. Editor: Zahid Ayub.

J. Thermal Sci. Eng. Appl 6(4), 041016 (Aug 26, 2014) (9 pages) Paper No: TSEA-14-1113; doi: 10.1115/1.4028179 History: Received May 03, 2014; Revised July 21, 2014

Performance of a direct evaporative cooler (DEC) was numerically studied at various outdoor and indoor air conditions, with geometric and physical characteristics of it being extracted based on thermal comfort criteria. For this purpose, a mathematical model was utilized based on the equations of mass, momentum, and energy conservation to determine heat and mass transfer characteristics of the system. It is found that the DEC can provide thermal comfort conditions when the outdoor air temperature and relative humidity (RH) are in the range of 27–41 °C and 10–60%, respectively. The findings also revealed that by raising the RH of ambient air, the system will reach the maximum allowed RH faster and hence a smaller heat exchanger can be used when the ambient air has higher RH. Finally, performance of the DEC in a central province of Iran was investigated, and a design guideline was proposed to determine size of the required plate heat exchangers at various operating conditions.

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Fig. 1

Schematic diagram of DEC

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Fig. 2

Diagram of comfort zone in ISO7730

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Fig. 3

(a) Schematic diagram of a heat exchanger of a DEC and (b) schematic diagram of an air channel in heat exchanger

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Fig. 4

(a) Water film temperature (results of Ref. [3]) and (b) water film temperature (modeling in this paper)

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Fig. 5

(a) Air temperature distribution in the symmetry plane of a channel (result of present study) and (b) air RH distribution in the symmetry plane of a channel (result of present study)

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Fig. 6

Reduction of air temperature in DEC when RH at the outlet reaches to 70%

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Fig. 7

Required channel width of DEC for providing outlet air with the RH of 70%



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