oa Thermal performance prediction of a single effect air-cooled absorption air conditioner with direct expansion evaporator

According to the World Resources Institute, in the building sector, commercial buildings contributed 9.9% of greenhouse gases (GHG) and 5.6% of GHG emissions are from residential buildings. In the Gulf, the building sector is the biggest electricity consumer. During the summer months, the local dry bulb temperature can go beyond 50°C therefore it is essential to depend on mechanical ventilation systems to reduce indoor temperature. In Qatar, the majority of residential buildings still rely on conventional vapour compression cycle systems for space cooling. The major drawback of this system is the high global warming potential (GWP) refrigerant and CO2 produced to power the compressor. Absorption cooling is a technology that has been disregarded in the past due to its low coefficient of performance (COP) compared to vapour compression cycle and lack of strong policies on GHG and CO2 emission. Recently, researchers and engineers started to focus on utilising absorption chillers for space cooling due to the advantage of its low carbon emission. Research in the past has shown that absorption chillers can cut down 16.7% of CO2 emission compared to vapour compression chillers. An absorption chiller is a machine that uses heat to drive the cooling system instead of electricity as commonly known in vapour compression refrigeration systems. The major difference between the two systems is that absorption refrigeration uses a heat source to increase the pressure at the condenser instead of a mechanical compressor. This makes the absorption refrigeration system very attractive when low grade heat is available. The objective of this study is to use a numerical method to predict the rate of heat transfer and thermal performance of a small capacity (3kW) air-cooled absorption system with a direct expansion evaporator. The parameters of the study focuses on the ambient temperature ranges from 28-35°C. The concept of air-cooled absorption refrigeration systems have become more acceptable due to the exclusion of cooling towers. Although cooling towers are a key component in absorption refrigeration systems, they often consume large volumes of water due to evaporation. Another disadvantage of cooling towers is that legionella contamination often occurs when the cycle is not properly maintained.