Theoretical performance study of a liquid desiccant regenerator supported with scavenging air heat exchanger

Abstract

This paper proposed a simplified theoretical model of the air and liquid desiccant parameters inside any packed bed liquid desiccant regenerator supported with scavenging air to air heat exchanger to reduce regeneration heat. The presented model depends mainly on the value of regenerator effectiveness regardless the packed bed structure type or the direction of flows inside the regenerator. Calcium chloride is used as desiccant material in this investigation. Both regenerator humidity and temperature effectiveness are applied for derivation of the numerical solution. The numerical solutions have showed good accuracy with a maximum deviation of 3.64% when compared with reliable experimental data available in the literature. The method developed here can be used in the quick prediction of the regenerator performance. The effects of variables such as air temperature and humidity, desiccant regeneration temperature, concentration, solution to air flow rate, and others on the regenerator performance have been investigated. The results reveal that operating variables such as desiccant concentration, desiccant regeneration temperature, and solution to air flow rate have the greatest impact on the performance of the regenerator. As a result of using scavenging air to air heat exchanger, the exit desiccant concentration increases by about 21.5% while the heat rate required for regeneration can be decreased by about 18% for the same exit concentration.