Project Advisor: Prof. R.A. Attalage
G.P.T.K. Abeysekara, K.H.H.G. Ketanwila, K.A.P. Vithana
Department of Mechanical Engineering, University of Moratuwa, Moratuwa, Sri Lanka
The purpose of this paper is to demonstrate the adaptability of evaporative cooling technology to Sri Lankan environment. Desiccant cooling technology is initiated to control the relative humidity level of the environment. A generic model of the evaporative cooler is constructed using direct evaporative cooling method and solid desiccant dehumidification method. The model was installed in the testing environment. The results show that the evaporative cooler is provided the sufficient level of thermal comfort to the people changing relative humidity slightly.
This paper based on the research and development project conducted by the undergraduates as requirement of fulfilling the degree to develop a cooler unit to suit industrial environment. Evaporative cooling is ancient and common technique within the middle-east countries. This paper discusses the applicability of evaporative cooling technique to the hot humid environment in Sri Lanka. On behalf of the industrial engineering context, human thermal comfort is key parameter of the efficiency and ergonomic aspects of man power. To maintain the optimum efficiency and industrial standards, maintaining a thermal comfort is essential requirement. Because of high relative humidity level in Sri Lanka, direct evaporative cooling can’t be used to reach required thermal comfort level. Solid dehumidification with heat exchanger was added to the design to overcome the problem. This paper analyses the results of the new method and attempts to provide acceptable, cost-effective solution. Dealing with small air capacities for evaporative cooling was difficult than large air volume. So another goal of this project is to check the adaptability to the industrial environment. Almost all industries produce waste heat, this project targets to utilize that heat as a source. 2. Methodology
Analysis for temperature and relative humidity readings of Sri Lanka was done and project objective were clearly identified. Existing evaporative cooling and desiccant cooling technologies were studied. Optimum design methodology was selected and cooler was fabricated to install in controlled environment. After the test runs of the machine, environmental data were collected and checked for the adaptability of concept. 2.1 Construction
Design is constructed by two major parts. Primary air preparation unit and evaporative chamber are those two key elements of the design. Atmospheric air is taken as the primary air. Dehumidification of primary air is done by Silica gel in the desiccant wheel and water evaporation is done by electronically controlled nozzles. In the desiccant wheel construction, flat iron was used to make the frame. No. 6 steel mesh is used to trap the Silica Gel in the wheel. Nuts and bolts were used to fix the desiccant particles to mesh. Wheel was rotated by a flat belt in the outer perimeter so that it causes minimum disturbance to the air flow. Special concern is taken to desiccant packing system to reduce pressure drop as well as to archive maximum efficiency of the wheel. 10mm Carbon steel mesh was used to fabricate the heat exchanging body of heat recovery wheel with the guidance of circular shaped flat iron frame supported by traverse iron bars. By increasing the number of layers, the total heat capacity of the wheel can be improved to meet the design requirements. Flow separation duct was constructed by 0.8mm a thick plate which is developed from semi circular shape to cross section with 2400 degree. 1200 duct resolute into a circular duct and also 1800 side. This duct was made with high precision to...