Experimental characterization of an ammonia – water – hydrogen diffusion absorption refrigeration system

Abstract

A diffusion absorption refrigerator (DAR) is a heat powered refrigeration system. It uses the ammonia-water mixture as a working fluid in addition to an auxiliary inert gas. In the present work, experimental investigation and dynamic analysis of the H2O-NH3-H2 diffusion absorption refrigeration system have been carried out using different values of thermal power input to the generator and evaporator load. Experimental results show that the temperature evolution of system components, transient response, amount of cooling below ambient, and coefficient of performance are significantly sensitive to the values of generator power input and evaporator load. Analysis of DAR system behavior for different start up conditions is used to estimate the time and energy required for the initiation of cooling effect. Steady-state experimental results obtained over a wide range of generator input power and evaporator load are used to characterize the unit performance. Performance maps useful for the design and integration of DAR systems with low-temperature energy sources are developed. These maps can be used to estimate the generator input power required for a given cooling load at a specified value of cooling temperature below ambient.