Waste Heat Recovery from Domestic Gas Geyser for Space Heating Application

Abstract

Most of the people in Pakistan use Gas Geysers in their homes to heat water for domestic usage. Flue gases at 250 Degree centigrade are being wasted from the top vent of Geyser whenever we turn it on. These gases are being wasted in the environment and are of no use. In winter season, people in Pakistan rely on Gas and Electric Heaters for Space Heating applications which are quite uneconomical sources. Our project is related to recovering this waste heat for space heating purposes. We have designed a heat exchanger which has Aluminum cylinders containing Phase Change Material. Phase Change Materials are an excellent source of storing and radiating heat, the PCM we have selected for this purpose is MgCl2.6H2o, this hydrated salt melts at 117 Degree centigrade. The operation takes two steps, first we charge our heat exchanger by placing it on the top of the geyser vent, Flue gases at 250 degrees Celsius enter our heat exchanger and escape the outlet vent of our heat exchanger at around 60 degrees Celsius thereby losing most of its energy to the Aluminum cylinders which ultimately melts the PCM in 35 Minutes. Once the heat exchanger is charged, it can be placed inside a room and a DC Fan can be attached to it’s outlet, the Fan convects hot air of temperature around 75 to 80 degrees Celsius for around one hour which increases the temperature of the room substantially.