Wind tunnel modeling the system performance of alternative evaporative cooling pads in Taiwan region
Resource
Building and Environment 37 (2): 177-187
Journal
Building and Environment
Journal Volume
37
Journal Issue
2
Pages
177-187
Date Issued
2002
Date
2002
Author(s)
Chiu, Kun-Hung
Abstract
A compact wind tunnel was developed to simulate evaporative cooling pad-fan systems and to provide direct measurement of system performance. Two alternative materials including one made of coarse fabric PVC sponge mesh 2.5 mm diameter in pinhole and one made of fine fabric PVC sponge mesh in 7.5 mm diameter pinhole were tested as pads in wind tunnel experiment. We have experimentally examined the effects of air velocity, water flow rate, static pressure drop across pad, and pad thickness on evaporative cooling efficiency. Pad face velocities and associated static pressure drops that allow a pad-fan system works were measured. The dimensionsless working equations of heat and mass transfer coefficients through various thickness of alternative pad media could be obtained through curve fitting technique based on the measurements. For coarse PVC sponge mesh, h H/h M = 1.33 ρaC PaLe 2/3(Le s/Le) 1/4; whereas for fine fabric PVC sponge mesh, h H/h M = 2.76ρaC PaLe 2/3(Le s/Le) 1/4 were h H is heat transfer coefficient, h M is mass transfer coefficient, ρa is air density, C Pa is specific heat of air, Le is Lewis number, and Le s is Lewis number at water temperature. Under a system setting of 15 1 min -1 m -2 water flow rate, pad thickness of 150 mm, and air velocities ranged from 0.75 to 1.5 m s -1, the cooling efficiencies for coarse fabric PVC sponge varied from 81.75 to 84.48%, whereas 76.68 to 91.64% for fine fabric PVC sponge. Results of this study will be used to determine operating protocols for future tests investigating criteria. © 2001 Elsevier Science Ltd. All Rights Reserved.
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