Experimental performance of evaporative cooling pad systems in greenhouses in humid subtropical climates

Xu, Jiaxing; Li, Y.; Wang, Ruzhu; Liu, W.; Zhou, Pin

doi:10.1016/j.apenergy.2014.10.061

Cited by 93 publications

(41 citation statements)

References 24 publications

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“…A greenhouse is a plastic or glass structure that can provide a suitable micro-climate for growing various crops and plants, protecting them from severe and variable outdoor weather conditions (Xu, Li, Wang, Liu, & Zhou, 2015). Controlling greenhouse micro-climate not only influences the growth of plants, but is also has a critical role in the spread of diseases inside the greenhouse.…”

Section: Introductionmentioning

confidence: 99%

Thermal performance of single span greenhouses with removable back walls

Wei

Guo

Wang

et al. 2016

Biosystems Engineering

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Section: Introductionmentioning

confidence: 99%

Thermal performance of single span greenhouses with removable back walls

Wei

Guo

Wang

et al. 2016

Biosystems Engineering

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“…The following formulas were used to calculate the elevation angle of the sun's rays: where δ = declination of the sun ( • ). From (1) and 2, we find the cosine of the zenithal angle:…”

Section: Methodsmentioning

confidence: 99%

“…All this requires the cultivation of a substantial number of crops in a protected environment. The use of greenhouses is one way to maintain crops and increase plant production despite a difficult and unstable external climate [1].…”

Section: Introductionmentioning

confidence: 99%

A Photovoltaic Greenhouse with Passive Variation in Shading by Fixed Horizontal PV Panels

Moretti

Marucci

2019

Energies

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The traditional shading systems that greenhouses use cause some of the solar radiation that is reflected or absorbed to be lost and, therefore, not used by the plants under cultivation. An interesting solution to these problems is to position photovoltaic (PV) panels on the roofs of greenhouses. All of the photovoltaic greenhouses that have been realized in Mediterranean areas are characterized by a fixed position of the PV panels and excessive shading, especially in autumn and winter. The purpose of this study is to describe a prototype of a photovoltaic greenhouse with both fixed and horizontal PV panels that exploit the natural variation in the elevation angle of the sun’s rays during the year to allow for “passive” variation in shading. The considerable variation in the elevation angle of the sun’s rays (from 24.4° to 71.1°) results in a high variation in shading (from 39.4% to 72.6%), with the highest values in the summer months and the lowest values in the winter months. This trend is favorable for meeting the photosynthetically active radiation (PAR) needs of greenhouse plants. If the plants under cultivation require more solar energy, it is necessary to increase the distance between the panels. We implement a specific mathematical relationship to define the precise distance to be assigned to the photovoltaic panels on the roof pitch.

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“…Other researchers combined indirect evaporative cooling heat exchanger with cooling pads in one experimental setup while using groundwater as a cooling agent, and the results showed an enhanced cooling efficiency compared with the mere direct evaporative cooling system [7]. For greenhouse applications, an experimental study showed a reasonable performance of evaporative cooling pads operating under humid subtropical climate [8].…”

Section: Introductionmentioning

confidence: 99%

QGreen Low-Carbon Technology: Cooling Greenhouses and Barns Using Geothermal Energy and Seawater Bittern Desiccant

Elsarrag¹,

Alhorr²

2018

Low Carbon Transition - Technical, Economic and Policy Assessment

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In hot-humid climates, cooling greenhouses and barns are needed to protect crops from extremely high temperature and to ensure high-yielding dairy cows. In Qatar, outside air temperature exceeds 46 C during summer, and the wet-bulb temperature can exceed 30 C which makes greenhouses and barns unworkable during this season. This study provides theoretical and experimental data for cooling greenhouses and barns using highly efficient and low-carbon technology (QGreen). QGreen uses groundwater (geothermal) for indirectdirect evaporative cooling coupled with desiccant dehumidification. The desiccant used is seawater bittern which is a by-product of the desalination process. A desiccant indirectdirect evaporative cooling panel system is designed and analyzed. The results show that the use of groundwater will enhance the efficiency and reduce the wet-bulb temperature dramatically. As a result, the efficiency of the overall cooling system is enhanced by more than 50% compared to the direct evaporative cooling efficiency that was recorded.

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Experimental performance of evaporative cooling pad systems in greenhouses in humid subtropical climates

Cited by 93 publications

References 24 publications

Thermal performance of single span greenhouses with removable back walls

Thermal performance of single span greenhouses with removable back walls

A Photovoltaic Greenhouse with Passive Variation in Shading by Fixed Horizontal PV Panels

QGreen Low-Carbon Technology: Cooling Greenhouses and Barns Using Geothermal Energy and Seawater Bittern Desiccant

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