Heat and mass transfer effectiveness of absorbers of absorption cooling systems

Abstract

A simplified heat and mass transfer model is used to obtain expressions for the mass transfer effectiveness and a heat transfer effectiveness for counter-flow absorbers. The effectiveness is a function of several dimensionless variables similar to those used in traditional heat exchanger design. The effectiveness is relatively insensitive to variations in the operating conditions of the absorber and depends mainly on the number of transfer units (NTU) and the capacity ratio. A log-mean-difference approach is used to extract the heat and mass transfer coefficients from experimental data on tubular absorbers.

Keywords:

• Vapour absorption cooling
• falling-film absorbers
• simplified modeling
• mass transfer effectiveness
• heat transfer effectiveness

Additional information

Notes on contributors

N E Wijeysundera

Nihal E Wijeysundera received his B.Sc.Eng. degree in Mechanical Engineering from the University of Ceylon, Srilanka and obtained his Ph. D. in Nuclear Reactor Physics from the University of Birmingham. Before joining the National University of Singapore (NUS) he was a senior lecture at the University of Peradeniya, Srilanka and an assistant professor at Drexel University, Philadelphia. He became a professor at NUS in 1997.

M D Raisul Islam

Md Raisul Islam obtained his PhD degree in Mechanical Engineering from the National University of Singapore (NUS) in 2003. Before joining Curtin University of Technology (Sarawak Campus) in 2006, he was involved in teaching and research in the same department of NUS mainly in the areas of Fluid Dynamics, Heat and Mass Transfer. His current research interests are in the areas of absorption cooling, drying processes and bio-thermal applications.

J C Ho

JC Ho received his B.Sc from London University and his M.S. and Ph.D. degrees from the University of Wisconsin. He joined the National University of Singapore in 1973. His research contributions are in the areas of: absorption processes, drying and heat pump drying applications, micro-turbines and biomass cogeneration applications He is the chief country coordinator for the EC-ASEAN Cogeneration Programme Phase 3 and the Singapore focal point for ASEAN Subcommittee on Non-Conventional Energy Research.