An Assessment of Different Boundary Conditions in a Naturally Ventilated Venlo-Type Greenhouse

Abstract

This paper presents a parametric study of the indoor climate of a four span greenhouse subjected to natural ventilation. The effect of different heat fluxes through the greenhouse covering on the airflow patterns as well as temperature and velocity distributions were determined. Appropriate effective heat flux boundary conditions were introduced in the CFD model to investigate temperature and velocity distributions at plant level. Initially, three different simulations were done to represent zero wind speed conditions. Secondly, a velocity of 1m/s was specified at the domain inlet boundary. Results indicated that for all cases, the velocity distribution was heterogeneous and quite high for wind still days around midday. Temperature distributions were more homogeneous, decreased with the presence of a wind. Results indicated that a parametric value of 20% of the maximum daily solar radiation approximates previously simulated wall temperatures. It was also concluded that design changes such as additional openings including side and/or more roof ventilators be utilized to enhance ventilation on wind still days, as well as the warmer parts of the day.

Research on the Microclimate of Protected Agriculture Structures Using Numerical Simulation Tools: A Technical and Bibliometric Analysis as a Contribution to the Sustainability of Under-Cover Cropping in Tropical and Subtropical Countries

“…For the case of Indonesia, Romdhonah et al [170,171] defined that the suitable greenhouse structure is the peak type, while for Korea, Rasheed et al [116], recommended the use of the Gothic greenhouse with conical roof, since these are the types of greenhouses that generate the best natural ventilation performance under the climatic conditions of each country. In China [15] and Thailand [151], the ventilation areas for a Chinese solar greenhouse and an arc-type greenhouse were redesigned to reduce the thermal gradients inside the structures. In Colombia, based on the limitations of the traditional greenhouse, two greenhouse models have been proposed: the DMG (curved multi-span design) and the GMG (Gothic multi-span design), greenhouses that have 19% more ventilation area, which allows higher ventilation rates and lower thermal gradients [29].…”

“…Simplified method 62 [19,32,[37][38][39]46,49,76,78,83,91,95,99,100,106,[108][109][110][111][113][114][115][116][120][121][122][123]126,129,131,133,136,[141][142][143][144][145][146][147][148][149]151,[153][154][155][156][159][160][161][163][164]…”