Analytical investigation for the solar heat driven cooling and heating system for the climatic condition of Dhaka

Abstract

Solar powered adsorption cooling system had been investigated with different adsorbate/adsorbent pair. For the climatic condition of Tokyo, utilizing silica gelwater pair, at least 15 collectors with cycle time 1500s have been found to be necessary to get required bed temperature of 85°C. Thus maximum cyclic average cooling capacity has been reported as 10kW at noon. Following this investigation a similar scheme has been taken in to consideration to utilize the climatic data of Dhaka for solar heat driven room cooling purpose. As Dhaka (Latitude 23°46'N, Longitude 90'23'E) isa tropical region and shortage in energy sector is a burning issue for this mega city, if solar insolation can be properly utilized for space cooling or cold storage purposes, country could gain a reasonable backup in energy sector. Based on these possibilities, an analytical investigation of solar heat driven adsorption cooling system has been done based on the climatic condition of Dhaka, where a two 'bed basic adsorption chiller with silica gel-water pair as adsorbent and adsorbate have been considered. The climatic data of a typical hot day of summer has been chosen in order to investigate for the optimum projection area, performances based on different collector number and cycle time. For the climatic condition of Dhaka, 22 solar thermal collectors consisting of a gross 0(53.13m2 projection area with 800s cycle time is needed for ,maximum cool.ing capacity of 11.9 kW.' For enhancement of chiller working hours a storage tank has been added with the adsorption cooling system in two different ways. It is observed that storage tank not only supports the chiller to remain active for a longer time; till 22.0h at night, but also prevents loss of heat energy. Furthermore, installed solar thermal collectors along with the hot water storage tank could be utilized for hot water supply for house hol~ use during the winter season which could again save notable amount of energy from primary energy sources like natural gas and electricity which are used for cooking and for water heating purposes.