Numerical study of thermal environment of a greenhouse dedicated to amaranth seed cultivation

In this study we examined thermal behavior inside a polycarbonate plastic greenhouse located in Amazcala, Querétaro, Mexico, in which amaranth is grown. The size of the greenhouse is 9.0 m long and 3.0 m high. The height of the entry opening and the exit opening is 0.5 m and 1.0 m, respectively. We conducted the study with real dimensions in a turbulent flow regime. Thermal radiation exchange between internal surfaces is also considered. Two case studies were undertaken: one with an outside temperature characteristic of a typical day and the other with a temperature corresponding to an extremely hot day. We modified the location of the hot wall, which was westward, northward and eastward. In both case studies we analyzed the Reynolds number in a range of 0 ⩽ Re ⩽ 4 × 104. We found that low airflow velocity numbers through the entry point did not benefit the thermal environment. On the contrary, the increase in Re at numbers above 2 × 104 was reflected in unnecessary electricity consumption. In the case of extremely hot days in the region, with temperatures of 35 °C, greenhouse ventilation with air from outside was insufficient to obtain temperatures suitable for the crop. Therefore, under these conditions, we recommend lowering the temperature of the airflow before it is introduced into the greenhouse.