1 Department of Mechanical Engineering, Punjab Agricultural University, Ludhiana-141004 (E-mail: vpsethi68@yahoo.co.in)
2 Energy Research Centre, Panjab Universiry, Chandigarh.
Experimental studies were conducted for thermal heating of an east-west, even span greenhouse using thermal energy of underground water. The system utilizes almost constant temperature of the underground water at around 24°C (year round) available on the surface in every agricultural field through deep tube well for sensible heating in winter conditions. Cool air from greenhouse and hot underground water are passed through a counter flow heat exchanger system designed around the perimeter of the greenhouse for providing the thermal comfort to the greenhouse. Experimental performance of the system is tested during the winter months of year 2004. Results show that the greenhouse air temperature is maintained about 7–9°C above ambient in winter conditions besides decreasing the temperature fluctuations inside the greenhouse and lowering the relative humidity. As a result, the vegetative growth of capsicum was almost doubled and yield obtained was almost 2.6 times as compared to open field conditions.
