BENCHMARK STUDY OF THE DISTANCE BETWEEN GREENHOUSES AND ITS EFFECT ON WIND DRIVEN VENTILATION

Abstract

The increasing demand for environmentally friendly quality products and the actual various standards that define the agricultural sector call for a restructuring of the greenhouse horticulture production sector. Nowadays, imported from industrial ecology, the concept of clustering has begun to be considered in agriculture. Therefore, Food-Parks and AgroParks are now familiar names in agriculture. This approach is certainly applicable and of great interest to Spain, where protected cultivation infrastructures are in the process of improvement and transformation. In this context it is of key importance the improvement of overall Agropark greenhouse natural ventilation. So, the aim of this preliminary study is to highlight the effect of the separation distances between greenhouses in an Agropark on wind driven ventilation efficacy. The basic multispan greenhouse was 96×6 m2 (12 spans of 8×6 m2 - length×height). Wind induced ventilation was operated by means of double ridge vents, so double ridge, windward and leeward ventilation configurations were studied. The basic Agropark configuration was 4 greenhouses in a row. Various separation distances referred to greenhouse height (H) - 1/2H, H, 2H, 5H and 10H - were simulated with a general purpose computational fluid analysis software (ANSYS Fluent). A RANS approach was considered because, for design purposes, just the mean physics involved in the ventilation process, and not their dynamics, are needed. Wind driven ventilation efficacy was defined as mean air velocity inside each greenhouse. Finally, the results showed consistency and illustrated that double ridge vent is the best configuration closely followed by windward ventilation one. First greenhouse always ventilates the best and the ventilation efficacy of subsequent greenhouses tends to this best value with increasing distance between greenhouses. Leeward ventilation generally had a worse behavior except for the closest separation distance of 1/2H.