Formulation and validation of a mathematical model for a naturally ventilated greenhouse with shading nets in warm and humid climate of India

Abstract

A thermal model is developed to investigate the suitability of a simple, inexpensive and naturally ventilated greenhouse with shading nets in warm and humid climatic condition for off-season cultivation of vegetables like okra, cucumber, etc. during winter. These vegetables are generally grown during summer and the rainy season. The study was conducted from November 2011 to February 2012 in OUAT, Bhubaneswar, and Odisha where warm and humid climate usually prevails. Air temperatures inside the greenhouse with shading net were only 1-2 • C higher during peak sunny hours and considerably 3-5 • C more during night hours compared with ambient air temperatures. Lowering of air temperature during peak sunny hours and increasing during the night due to use of shading nets would become favourable for growing off-season vegetables in naturally ventilated greenhouse. Predicted values of air and plant temperatures were found to be in close agreement with experimental values.

Thermal Analysis and Experimental Validation of Environmental Condition Inside Greenhouse in Tropical Wet and Dry Climate

“…As can be seen from Figure 2, the predicted temperatures of greenhouse air and plants were relatively near to the experimental temperatures. Similar observations were reported by Ghosal and Mishra [4]. The statistical analysis of the root mean square percent deviation (e), a coefficient of correlation (r), mean bias error (MBE), and the root mean square error between the predicted and experimental values verified these.…”

“…Assuming that the heat transfer coefficients, temperature, and total solar radiation are constant for ∆t time interval (∆t = 1 h), this is the general solution [4,13]:…”

“…The parameters associated with the model development and experiments are considered based on the local climate condition and available greenhouse (A c , A g , A p , A d , M p , T 0 , and τ). Some parameters are considered based on the published research by Ghosal and Mishra [4] (h pr , h a , h r , N, v, and C p ) and Mobtekar et al [2] (α g , α p , ρ c , U tc , and h d ). This study was to explore the energy utilization of greenhouse for maintaining desirable plant temperature (approximately 29 • C) inside greenhouse.…”

“…The combination of the design features for an energy efficient greenhouse suitable for cold weather conditions reduced the greenhouse heating requirements by 80%. Ghosal and Mishra [4] developed a quasi-steady-state thermal model to investigate the suitability of a naturally ventilated, inexpensive, and simple greenhouse with shading nets in the humid and warm climate of Bhubaneshwar, Odisha (India) during winter. It was reported that for the greenhouse with a net shading, the temperature variations were lower as compared to greenhouse without the shading net.…”

Navigating Challenges and Prospects in Off-Season Vegetable Production

“…Ramasamy et al (2021) noted the yield of white and red amaranths was consistently better (7.68-19.70 t/ha) under pink poly-net house in all the seasons, but the yield of water spinach was consistently better under white polynet house (16.25-20.88 t/ha). Capsicum cultivation under shade nets during the off-season results in higher yields compared to open-field conditions (Ghosal and Das, 2012). The production of bitter gourd in the late kharif season, considered off-season cultivation, has been successful (Asati et al, 2018).…”