Modelling and performance analysis of a cross-flow type plate heat exchanger for dehumidification/cooling

This paper describes the performance analysis of a cross-flow type plate heat exchanger for use as a liquid desiccant absorber (dehumidifier) and indirect evaporative cooler. The proposed absorber can be described as a direct contact, cross-flow, heat and mass exchanger, with the flow passages separated from each other by thin plastic plates. One air stream (primary air) is sprayed by liquid desiccant solution, while the other stream (secondary air) is evaporatively cooled by a water spray. Each thin plate, besides separating the water/air passage from the solution/air passage, also provides the contact area for heat and mass transfer between the fluids Rowing in each passage. A parametric study for the primary air stream at 33 degreesC 0.0171 kg/kg, humidity ratio and secondary air stream at 27 degreesC and 0.010 kg/kg humidity ratio using calcium chloride solution was performed in this study. The results showed a strong dependence on the heat and mass transfer area, solution concentration and ratio of secondary to primary air mass Row rates. However, negligible differences were found between the performance of a counter flow and a parallel flow arrangement. The results demonstrate that the proposed absorber will not offset both the latent and sensible load of the primary air and, therefore. an auxiliary cooler or more dehumidification/indirect evaporative cooling stages will generally be required to meet the sensible and latent load in a typical comfort application. (C) 2001 Elsevier Science Ltd. All rights reserved.