Thermal Design and Parametric Study of a Greenhouse in Microgravity Conditions

The recent progress in commercial space flights and prospects for interplanetary space missions has attracted more attention towards developing sustainable built environments in microgravity conditions. An important factor in establishing a sustainable living condition for outer space applications is the ability to produce food. The thermal design considerations in a greenhouse have a major impact on the survival, water efficiency, quantity, and quality of plants produced. The extremely low environmental temperatures necessitate the use of heaters which do consume energy. Given the scarcity of energy access, it is important to achieve proper thermal conditions with the lowest possible energy requirements. This paper discusses the thermal design and considerations of a greenhouse in a microgravity environment (i.e. Martian environment) with extremely low ambient temperature conditions (nearly −200 K) and limited availability of solar radiation (maximum of 590 W/m 2). A parametric study is performed using COMSOL Multiphysics. The effects of varying several design parameters including heater capacity, and placement of heaters are investigated on the indoor thermal condition of the greenhouse. The temperature distribution inside the greenhouse is assessed for several design conditions and the desirable distributions for plant growth are further analyzed. The impact of microgravity conditions is also assessed through a comparison of results between microgravity and normal gravity conditions. The results from this study could be used towards the proper thermal design of greenhouses for the extreme conditions of outer space applications.