Modeling of earth tube heat exchanger and blower operated by solar photovoltaic modules for room air conditioning

Abstract

The work of the present paper deals with the use of a blower powered by solar photovoltaic modules where ambient air is pumped through a series of pipes passing through the earth’s crust at a particular depth. The ambient air passing through pipes exchanges thermal energy within the earth’s crust and the air temperature obtained is supplied to a room of 25 m3. The analysis is made for January and May of Guwahati city, Assam, India because if the system works well in minimum temperature and minimum solar radiation (January), and maximum temperature and maximum solar radiation(May) it will work well throughout the year. In January ambient air is pumped by the blower through a series of pipes to a depth of 3.04m having a temperature of 24°C[23] After passing through a particular length at 3.04m depth ambient air in January attains 24°C and is sent to room maintaining at 24°C. In May after passing through a particular length at 3.04m depth ambient air attains 24°C. This 24°C air is again sent through well water situated at a depth of 10m[11] from the earth’s surface and temperature of 18 °C[12]. This 24°C air attains 18 °C after passing through a particular length and is pumped to a room that is maintained at 18 °C. For powering the blower, 2 modules in parallel and series of model SW280 solar photovoltaic modules are sufficient and extra current after meeting the blower requirement is stored in a rechargeable battery. The amount of charge stored and discharged in January and May is 20.294Ah, 1.472 Ah, and 21.979 Ah, 5.463 Ah respectively with a battery capacity of 28.352 Ah.