Abstract:
Agriculture has been a vital part of every civilization and era since it has been practiced. In general,
it serves two major purposes; meeting the food demands and supporting the economic
infrastructure of a country. Similarly, agriculture sector of Pakistan is the backbone of food and
economic sector. However, the conventional agricultural norms greatly rely on natural climate
consequently making the crop productivity vulnerable to catastrophic climate changes, unwanted
atmosphere and natural disasters. The modern era, under the great pressure of increasing
population and demand of food, is committed to investigate and design smart agricultural systems
that need lesser cultivation land with maximized yield by improvising optimum crop growth
requirements. This research is intended to contribute in this domain by designing a temperature
control system for a greenhouse. At first, greenhouse has been mathematically modeled using eight
different types of subsystems, among which six mimic the heat losses during the whole day cycle
while two heat gain subsystems, solar (natural) and designed heat gain system have been modeled
to compensate for the heat losses thus maintaining the optimum set temperature. The set
temperature has been maintained throughout the day using geothermal energy wherever the solar
energy failed to do so. Geo thermal bare tube heating system is proposed due to being cost effective
and renewable where the optimum set point is met in real-time through hot water flow rate control.
The modeled greenhouse system with proposed controller has been simulated in Matlab®
Simulink. It is observed that the proposed greenhouse temperature control system robustly
maintains set point temperature by actuating water flow valve. The proposed system is designed
as per Pakistan’s climate and highly cultivated crops temperature needs.
