Retrofit of a liquid desiccant and evaporative cooling-assisted 100% outdoor air system for enhancing energy saving potential

The objective of this research is to retrofit a liquid desiccant (LD) and indirect/direct evaporative cooling assisted 100% outdoor air system (LD-IDECOAS) to enhance its operating energy saving potential. Two retrofit cases of existing LD-IDECOAS have been considered. The first case involves replacing the indirect and direct evaporative coolers with an M-cycle or a dew-point indirect evaporative cooler (i.e., Case 1), and the other one involves adding an enthalpy exchanger before the LD unit of the system in case 1 (i.e., Case 2). By conducting detailed energy simulations for each retrofit case, the improvements in operating energy saving and the coefficient of performance (COP) over the existing LD-IDECOAS were quantitatively evaluated. The results showed that case 1 might provide enhancement in cooling capacity and thermal COP; however, the heating energy consumption for regenerating the desiccant solution increased with the higher process airflow rate when compared to the existing LD-IDECOAS. It was also found that the cooling capacity, thermal COP, and primary COP could be improved by adding a membrane enthalpy exchanger, as done in case 2, without any significant increase in the heating energy consumption for regenerating the desiccant solution. (C) 2016 Elsevier Ltd. All rights reserved.This work was supported by a National Research Foundation (NRF) grant funded by the Korean government (No. 2015R1A2A1A05001726)