Comparison between two LiBr–H2O absorption-compression chillers and a simple absorption chiller driven by various solar collectors: Exergy-economic performance and optimization

Abstract

Although some studies have been conducted on various types of compressor-based absorption chillers (ACH), a comprehensive comparison of the performances of these configurations has not been made. In addition, selecting a proper solar collector in combination with the best compressor-based ACH is worthwhile as solar energy is widely available during the summer season. For this purpose, the exergy-economic performances of 12 LiBr–H2O chiller configurations are compared in the present study to produce 100 kW of cooling. The configurations are a single-effect ACH and two absorption-compression chillers (ACCH) driven by 4 collector types, namely, a flat plate collector (FPC), an evacuated tube collector (ETC), a parabolic trough collector (PTC), and a compound parabolic collector (CPC). In ACCH 1, a compressor is embedded between the evaporator and the absorber of the ACH. In ACCH 2, a compressor is employed between the generator and the condenser of the ACH. The outcomes of the research indicate the superiority of the PTC and ETC over the two other collector types in terms of exergy efficiency and economic performance, respectively. The highest exergy efficiency and lowest total cost rate are calculated as 4.8% and 23.58 $h−1, which are obtained by the PTC-driven ACCH 1 and ETC-driven ACCH 1, respectively. Nevertheless, the unit cost of cooling produced by these two layouts is too high compared to the other configurations. Hence, they cannot be selected as the best configuration. Instead, the ETC-driven ACCH 2 is selected as the best configuration since it brings about the lowest unit cost of cooling (20.45 $GJ−1), and it has acceptable values of exergy efficiency (4.11%) and total cost rate (29.3 $h−1).