In this paper, numerical analyses of the thermal performance of an indirect evaporative air cooler incorporating a M-cycle cross-flow heat exchanger has been carried out. The numerical model was established from solving the coupled governing equations for heat and mass transfer between the product and working air, using the finite-element method. The model was developed using the EES (Engineering Equation Solver) environment and validated by published experimental data. Correlation between the cooling (wet-bulb) effectiveness, system COP and a number of air flow/exchanger parameters was developed. It is found that lower channel air velocity, lower inlet air relative humidity, and higher working-to-product air ratio yielded higher cooling effectiveness. The recommended average air velocities in dry and wet channels should not be greater than 1.77 m/s and 0.7 m/s, respectively. The optimum flow ratio of working-to-product air for this cooler is 50%. The channel geometric sizes, i.e. channel length and height, also impose significant impact to system performance. Longer channel length and smaller channel height contribute to increase of the system cooling effectiveness but lead to reduced system COP. The recommend channel height is 4 mm and the dimensionless channel length, i.e., ratio of the channel length to height, should be in the range 100 to 300. Numerical study results indicated that this new type of M-cycle heat and mass exchanger can achieve 16.7% higher cooling effectiveness compared with the conventional cross-flow heat and mass exchanger for the indirect evaporative cooler. The model of this kind is new and not yet reported in literatures. The results of the study help with design and performance analyses of such a new type of indirect evaporative air cooler, and in further, help increasing market rating of the technology within building air conditioning sector, which is currently dominated by the conventional compression refrigeration technology.
[1]
Donal Finn,et al.
Indirect evaporative cooling potential in air-water systems in temperate climates
,
2003
.
[2]
Saffa Riffat,et al.
Dynamic performance of a novel dew point air conditioning for the UK buildings
,
2009
.
[3]
V. Sethi,et al.
Survey of cooling technologies for worldwide agricultural greenhouse applications
,
2007
.
[4]
P. J. Erens,et al.
Modelling of indirect evaporative air coolers
,
1993
.
[5]
Yang Hongxing,et al.
An analytical model for the heat and mass transfer processes in indirect evaporative cooling with parallel/counter flow configurations
,
2006
.
[6]
Robert Tozer,et al.
Cooling tower—an energy conservation resource
,
1999
.
[7]
J. Lienhard.
A heat transfer textbook
,
1981
.
[8]
Robert E. Wilson,et al.
Fundamentals of momentum, heat, and mass transfer
,
1969
.
[9]
N. J. Stoitchkov,et al.
Effectiveness of crossflow plate heat exchanger for indirect evaporative cooling
,
1998
.
[10]
Yunus Cerci,et al.
A new ideal evaporative freezing cycle
,
2003
.
[11]
P. J. Banks,et al.
A General Theory of Wet Surface Heat Exchangers and its Application to Regenerative Evaporative Cooling
,
1981
.
[12]
G. P. Maheshwari,et al.
Energy-saving potential of an indirect evaporative cooler
,
2001
.
[13]
William M. Worek,et al.
THE EFFECT OF LONGITUDINAL HEAT CONDUCTION IN CROSS FLOW INDIRECT EVAPORATIVE AIR COOLERS
,
2007
.
[14]
Saffa Riffat,et al.
Comparative study of heat and mass exchanging materials for indirect evaporative cooling systems
,
2008
.