Dae-Young Lee

Energy Mechanics Research Center, Korea Institute of Science and Technology, Seoul 136-791, KOREA

*E-mail : ldv@,kist. re. kr

Abstract

The cooling capacity and the energy efficiency of the desiccant cooling system can be improved by incorporating a regenerative evaporative cooler instead of a direct evaporative cooler. The regenerative evaporative cooler is to cool a stream of air using the evaporative cooling effect without an increase in the humidity ratio. In this study, a prototype of the desiccant cooling system incorporating a regenerative evaporative cooler was designed, fabricated and tested for the performance evaluation. To this purpose, two important components, i. e., the regenerative evaporative cooler and the desiccant rotor were developed and assembled into the system. The regenerative evaporative cooler was built by compiling multiple pairs of aluminium plates and fins and the desiccant rotor was fabricated using polymeric desiccant. The exterior dimension of the completed prototype is 700(W) x 800(D) x 1,900 mm(H). The prototype was tested at the ARI condition (indoor: 27oC, 50%RH, outdoor: 35oC, 40%RH) for performance evaluation. With the regeneration air temperature of 60oC and the ventilation ratio of 0.3, the cooling capacity was measured as 4.4 kW and COP as 0.76.

Keyword: desiccant cooling system, regenerative evaporative cooler, prototype

1. Introduction

The desiccant cooling system has been investigated for years as an alternative option to conventional vapor compression cooling systems[1-4]. In a desiccant cooling system, air is dehumidified passing through a desiccant rotor and then is cooled in a series of a sensible heat exchanger and an evaporative cooler to achieve the desired air condition. This system works without CFC’s or other similar ozone-depleting chemicals but only uses water as the working fluid. It provides cooling by the use of thermal energy instead of electricity contributing to peak demand reduction of the electricity. The solar energy, the waste heat from plants, etc. can be applied as the source of the thermal energy. In such cases, the desiccant cooling technology can greatly contribute to energy saving and CO2 reduction by using the energy unutilized otherwise and thus reducing the consumption of fossil fuels.

In this study, a prototype of the desiccant cooling system incorporating a regenerative evaporative cooler was designed, fabricated and tested for the performance evaluation. The prototype was designed to show 4 kW cooling capacity at the ARI condition (indoor: 27oC, 50%RH, outdoor: 35oC, 40%RH) with the hot water supply of 70oC as the heat source. To this purpose, two important components, i. e., the regenerative evaporative cooler and the desiccant rotor were developed and assembled into the system. The regenerative evaporative cooler was built by

compiling multiple pairs of aluminium plates and fins and the desiccant rotor was fabricated using the polymeric desiccant, SDP.