Effect of Radiative Heat Transfer and Boundary Conditions on the Airflow and Temperature Distribution Inside a Heated Tunnel Greenhouse

Zeroual, S.; Bougoul, S.; Benmoussa, H.

doi:10.1134/s0021894418060068

Cited by 11 publications

(7 citation statements)

References 11 publications

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“…The results of the simulations (Table 7) show that when there was a change in the intensity of NIR, the highest thermal gradient (0.23 • C) occurred at the inlet and outlet areas of span 2 of the greenhouse, where the wind speeds were below 0.01 m s −1 and air movement was generated by the convective effect caused by temperature differences. This was also demonstrated by Sun et al, and Zeroual et al [3,7], where outside wind speeds close to 1 m s −1 were insufficient to renew the air inside the greenhouse, affecting the exchange of heat and mass between the outside and the inside. Derived from the change in the concentration of the mass fraction of water vapor and the NIR intensity in the simulated scenarios, the highest thermal gradient occurred in the inlet area (0.29 • C), where the RH of the greenhouse was higher due to the air exchange between outside and inside.…”

Section: Analysis Of the Results Of Simulated Scenariossupporting

confidence: 62%

“…In 2017, Cemek et al [4] concluded that ventilation efficiency should be further analyzed with the aim of establishing the best environmental conditions favoring plant growth parameters. Wind speed and direction are factors impacting the environmental comfort of the internal climate of a greenhouse, specifically in terms of the exchange of heat and mass between the inside and outside [5][6][7]. The ventilation system of a greenhouse may eliminate excess heat and maintain acceptable CO 2 and water vapor levels for crops [8,9].…”

Section: Introductionmentioning

confidence: 99%

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Simulation of Water Vapor and Near Infrared Radiation to Predict Vapor Pressure Deficit in a Greenhouse Using CFD

et al. 2021

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Vapor pressure deficit (VPD) can be used as an indicator to schedule greenhouse irrigation. VPD can be estimated as a function of relative humidity (RH) and temperature (T). The objective of this work was to analyze spatial variation in VPD as an indicator of water stress influenced by concentration of water vapor and intensity of near infrared (NIR). The study was carried out in an empty three-span sawtooth greenhouse with natural ventilation under the local climate in Montecillo, Mexico; these findings established a base value to analyze greenhouse field conditions prior to the influence from a crop. The experimental phase consisted of recording data (3 February 2019–24 February 2019) on temperature, humidity, solar radiation, and wind speed, which were used for developing a model in computational fluid dynamics (CFD). Then, this model was used to estimate VPD, considering changes in mass fraction of water vapor and the intensity of NIR. Scenarios with 50, 70, and 90% external RH were evaluated. It was found that without a crop, temperature was not affected by the variation in the mass fraction of water vapor and the intensity of NIR in the simulated scenarios, each of which generated a thermal gradient within the range of 4 °C. When considering the scenario of 90% external RH, we found the best VPD range along the greenhouse (2–3 kPa) that would be a favorable field condition for crops. Differences between VPD with and without a crop can be used to estimate the water quantity needs for crop growth based on the climate variables examined in this study, where higher VPD values require more water for irrigation.

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Section: Analysis Of the Results Of Simulated Scenariossupporting

confidence: 62%

Section: Introductionmentioning

confidence: 99%

Simulation of Water Vapor and Near Infrared Radiation to Predict Vapor Pressure Deficit in a Greenhouse Using CFD

et al. 2021

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“…This model has been used widely by several authors to simulate the airflow inside greenhouses and was validated in several greenhouse CFD studies [9,10]. To avoid the limitations of the k-ε model in predicting the flows close to the walls, we use the wall function depending on wall-normal distance y + , which has a value slightly greater than y + =30.…”

Section: Mathematical Formulationmentioning

confidence: 99%

Simulation of Natural Ventilation Inside Tunnel Greenhouse

Lebbal¹,

Bougoul²,

Zeroual³

2020

IJHT

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A study of the variation of the temperature and the speed under an open greenhouse with and without plant was developed and the effect of the wind speed on the internal climate under the greenhouse was analyzed by the use of the software Fluent-CFD based on the finite volume method. The airflow through the crop was introduced by using the porous medium approach. Three dimensional simulations which described turbulent flows in steady state were carried out and the turbulence was modeled by using the standard k-ε model. The air temperature variation shows a gradient from the sidewalls towards the center of the greenhouse due to the movement of the hot air rising towards the roof and another vertical gradient due to the air circulation above the surface of the heated floor. At the openings, the maximum air velocity was reached and the lowest values are observed in the middle of the greenhouse, at the crop level and at the corners. The variation of the climatic parameters affects greatly the growth of the plant. The results of the simulation given as airflows and temperature patterns are satisfactory while comparing them to those of the literature. These results can help to know the distribution of the internal climate inside the greenhouse, so they facilitate the openings design.

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“…The technologies used are mainly renewable and sustainable solutions such as solar thermal complexes (T), photovoltaic (PV) modules, phase change materials (PCM), underground systems, photoelectric sensors and hybrid systems, heat storage technologies, Energy-saving and heat-saving pumps. Zeroual et al [15] studied numerically the airflow and temperature distribution in a heated tunnel greenhouse in the presence of a row of tomato plants owing to heat dissipation from heating pipes. The radiation heat transfer is taken into account by using the model of discrete ordinates.…”

Section: Introductionmentioning

confidence: 99%

Heat and Fluid Flow in an Agricultural Greenhouse

Ghernaout¹,

Attia²,

Bouabdallah³

et al. 2020

IJHT

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In this work, we interested to the numerical simulation of natural convection in a closed model greenhouse heated by tubes. A greenhouse box subjected to different boundary conditions on the roof like the imposed temperature, convective flux and mixed flux was studied. The considered mathematical model is a system of partial differential equations formed by the continuity, the momentum and the energy equations. The commercial Computational Fluid Dynamics (CFD) code Fluent was used for numerical simulations based on a finite volume method. In each case, we have studied the thermal and dynamic flow parameters in the greenhouse, such as the average velocity and the average temperature. The obtained results present a good agreement with the experimental data and show a strong dependence of the air climate in the greenhouse. These results help the farmers to set up a greenhouse with materials and dimensions suitable for external conditions.

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Effect of Radiative Heat Transfer and Boundary Conditions on the Airflow and Temperature Distribution Inside a Heated Tunnel Greenhouse

Cited by 11 publications

References 11 publications

Simulation of Water Vapor and Near Infrared Radiation to Predict Vapor Pressure Deficit in a Greenhouse Using CFD

Simulation of Water Vapor and Near Infrared Radiation to Predict Vapor Pressure Deficit in a Greenhouse Using CFD

Simulation of Natural Ventilation Inside Tunnel Greenhouse

Heat and Fluid Flow in an Agricultural Greenhouse

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