Evaluation of the cooling, heating and water demands for tomato production in a solar greenhouse by integrating the solar energy, evapotranspiration and TOMGRO models

Abstract

The design, operation and maintenance of solar greenhouses in optimum condition can improve the water and energy consumption and agricultural production. This study has been integrated the energy, humidity and growth models to determine the cooling, heating and water requirements for producing tomato in the even span, uneven span and arc roof type greenhouse structures with north–south and east–west orientations. In the proposed integrated framework, firstly, the incident and transmitted diffuse, direct and ground solar radiations for any side of solar greenhouse, along with different evapotranspiration models and TOMGRO model for tomato growth and production have been assessed comprehensively. Then, by using the set point day and night temperatures and relative humidity the phenomena of the energy and water transfer such as convection, longwave radiation, infiltration, and cover condensation as well as TOMGRO state variables have been calculated. By considering the temperature, humidity, structure and orientation as decision variables, the east–west uneven span structure with day/night temperatures of 20/16 °C and relative humidity of 80 % is recommended as the best case in Pakdasht city of Iran. This solar greenhouse requires 0.92 MW/m2 and 3.83 MW/m2 heating and cooling energy, respectively, to produce 46.68 kg/m2 mature tomatoes during the whole cultivation period. This research has provided a tool to select the most appropriate structure and orientation of a solar greenhouse in any location based on the trade-off between energy and water consumption and tomato production.