Analytical and numerical study of a controlled-environment agricultural system for hot and dry climatic conditions

SUMMARYIn this communication, thermal model of a greenhouse has been developed by incorporating the effect of water wall in the north side. Various temperatures, namely plant, water wall and room temperatures as a function of climatic and design parameters have been obtained by solving coupled single-order differential equation using Runge-Kutta method. Numerical methods have been carried out for a typical day of winter for Delhi condition. It has been observed that there is significant effect in the plant, room air and water temperatures due to change in fraction of solar radiation incident on north wall (F n ) and heat capacity of water wall.Experimental validation of the proposed model for a greenhouse with brick north wall has also been carried out. It has been observed that there is a fair agreement between experimental and theoretical values.

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“…The T LL should be minimum for cooling mode and vice versa for heating mode, (Sutar and Tiwari, 1995;Singh and Tiwari, 2000).…”

Section: Energy Balancementioning

confidence: 99%

“…For the given temperature difference (numerator), the denominator should be as large as possible for the growth of plants. The T LL should be minimum for cooling mode and vice versa for heating mode, (Sutar and Tiwari, 1995;Singh and Tiwari, 2000).…”

Section: Energy Balancementioning

confidence: 99%

Effect of thermal storage on the performance of greenhouse

Din

Tiwari

Ghosal

et al. 2002

Int. J. Energy Res.

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“…The internal temperature was reduced by 41% in the wetted greenhouse compared with 18% for the control. In another study, Sutar and Tiwari [120] experimentally evaluated the effectiveness of roof evaporative cooling with and without shading cloth. Temperatures were reduced by 10 • C in the shaded greenhouse and by 4-5 • C in the unshaded greenhouse.…”

Section: Roof Evaporative Coolingmentioning

confidence: 99%

Protected Cropping in Warm Climates: A Review of Humidity Control and Cooling Methods

2019

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The projected increase of the world’s population, coupled with the shrinking area of arable land required to meet future food demands, is building pressure on Earth’s finite agricultural resources. As an alternative to conventional farming methods, crops can be grown in protected environments, such as traditional greenhouses or the more modern plant factories. These are usually more productive and use resources more efficiently than conventional farming and are now receiving much attention—especially in urban and peri-urban areas. Traditionally, protected cropping has been predominantly practised in temperate climates, but interest is rapidly rising in hot, arid areas and humid, tropical regions. However, maintaining suitable climatic conditions inside protected cropping structures in warm climates—where warm is defined as equivalent to climatic conditions that require cooling—is challenging and requires different approaches from those used in temperate conditions. In this paper, we review the benefits of protected cropping in warm climates, as well as the technologies available for maintaining a controlled growing environment in these regions. In addition to providing a summary of active cooling methods, this study summarises photovoltaic (PV)-based shading methods used for passive cooling of greenhouses. Additionally, we also summarise the current humidity-control techniques used in the protected cropping industry and identify future research opportunities in this area. The review includes a list of optimum growing conditions for a range of crop species suited to protected cropping in warm climates.

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“…In Oman, utilization of two evaporative cooling pads, instead of the conventional single pad cooling system, resulted in lowering the water temperature up to 3 C and in increasing the relative humidity to 100% (Davies and Paton 2005). In Dubai, integrating the evaporative pad cooling system with an array of pipes produced shade and mitigated the buoyancy effects (Sutar and Tiwari 1995).…”

Section: Greenhouse Evaporative Cooling Systemmentioning

confidence: 99%

Experimental and numerical investigation of the thermal performance of evaporative cooled greenhouses in hot and arid climates

Ghаni

El-Bialy

Bakochristou

et al. 2019

Science and Technology for the Built Environment

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The controlled microclimate of greenhouses is vital for producing quality yield. This paper investigates the thermal performance of an evaporative cooled greenhouse operating in Qatar. Three design factors affecting the greenhouse thermal performance were assessed, namely the greenhouse geometry, operational parameters, and its geographical location. Geometrical parameters include induction fan elevation, roof shape, and aspect ratio. Operational parameters refer to the air flowrate. The greenhouse location dictates the incident solar intensity that was studied. Computational Fluid Dynamics (CFD) was used to model a typical ASHRAE compliant greenhouse. The simulation results were validated using measured data of a greenhouse inner air temperature, relative humidity, and the global incident solar radiation, showing good agreement. Simulation results showed that induction fans located at or below the crop height resulted in lowering the average temperature of the greenhouse. Doubling of the greenhouse ventilation rate from 20 ACH to 40 ACH further decreased the greenhouse air temperature. Temperature rise due to high incident solar radiation is reduced by increasing the ventilation rates. The uneven span greenhouse roof shape resulted in the lowest average inner temperature. For the same greenhouse floor area and volume, the effect of the aspect ratio showed negligible differences.

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Analytical and numerical study of a controlled-environment agricultural system for hot and dry climatic conditions

Cited by 32 publications

References 9 publications

Effect of thermal storage on the performance of greenhouse

Effect of thermal storage on the performance of greenhouse

Protected Cropping in Warm Climates: A Review of Humidity Control and Cooling Methods

Experimental and numerical investigation of the thermal performance of evaporative cooled greenhouses in hot and arid climates

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