The effect of bench arrangements on the indoor climate of naturally ventilated greenhouses

Abstract

Paper presented at the 8th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Mauritius, 11-13 July, 2011.

Greenhouses are used worldwide to effectively produce crops and flowers out of season by protecting them from adverse environmental factors [2]. High inputs (water, nutrients, plant protection chemicals, handling material and fossil energy) are required for this method of production, which may unfortunately lead to environmental problems [3]. Due to an increased interest in reducing energy consumption, natural ventilation has become a popular alternative method to control the indoor climate of greenhouses. Effective control of the indoor climate of greenhouses is of vital importance, as this directly influences the quality and quantity of the crop production. The purpose of this paper is to investigate the effect

of bench arrangements on the internal environment in naturally ventilated Venlo-type greenhouses. The study will be conducted numerically, using computational fluid dynamics (CFD). Two-dimensional models will be created and a mesh sensitivity study will be conducted to determine a suitable mesh size. The effect of various bench arrangements used commonly in industry on the temperature and velocity distributions inside the greenhouses will be assessed. The case of a heated floor will be examined, with single, double and triple solid bench arrangements. A three-dimensional double span greenhouse will also be created containing four longitudinally arranged benches, and compared to a corresponding two-dimensional model. It was found that overall the wind direction and bench arrangements do have a significant effect on the microclimate at plant level, creating large velocity and temperature differences between the various bench arrangements.