Energy Efficiency in Greenhouse Evaporative Cooling Techniques: Cooling Boxes versus Cellulose Pads

Franco, Antônio; Valera, D.L.; Peña, Araceli

doi:10.3390/en7031427

Cited by 74 publications

(44 citation statements)

References 17 publications

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“…Hence the needs for the cooling unit as our greenhouses not well tight as mentioned by Franco et al, (2014). The CU system could be doubled or the face area of the media could be increased to achieve the desired cooling capacity.…”

Section: Resultsmentioning

confidence: 99%

“…These materials are placed in such a way as to ensure that they present the maximum possible transfer surface and the minimum resistance to the passage of the airflow. Franco et al, (2014) stated that an alternative to the use of the fog system in greenhouses would be the use of evaporative cooling boxes. This direct evaporative cooling technology is still evolving and incorporating a dehumidification system by means liquid desiccant to reduce the humidity of the ambient air and therefore achieve greater reduction in air temperature.…”

Section: Introductionmentioning

confidence: 99%

“…One of the most efficient approaches to reduce the difference between the inside and outside air temperatures is to improve ventilation system. Franco et al, (2014) stated that forced greenhouse crops are an ever more common means of cultivation worldwide. Current estimates put the surface area dedicated to such crops at 700,000 ha, 150,000 of which are located in the Mediterranean basin.…”

Section: Introductionmentioning

confidence: 99%

“…This is essential in hot and humid climatic areas where the efficiency of these direct systems is low, (Farmahini et al, 2012). Franco et al, (2014) stated that evaporative cooling systems using a combination of evaporative pads and extractor fans require greenhouses to be airtight. They compared the performance of evaporative cooling boxes with four pads of different geometry and thickness manufactured by two different companies.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Improving Performance of the Evaporative Cooling System inside the Greenhouses and Its Effect on Tomato Productivity

G.D.M.

T.R.

Mostafa

2015

Alexandria Science Exchange Journal: An International Quarterly

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An experimental study was conducted to determine the performance of two evaporative cooling systems, as well as the gradients of temperature and humidity along a greenhouse. The first system was the cooling unit, (CU) compared with the traditional fan-pad one, (F-P). The cooling unit was connected with two perforated ducts inside the greenhouse. The air temperatures and relative humidities on the longitudinal axis were measured outside and just after leaving the media and at each one meter from the pad media. They were also, measured in the traverse axis parallel to the pad media at distances 0.5, 1.5, 2.5 and 3.5 m from the edge of the greenhouse. A steady state mathematical model was modified to predict the greenhouse air temperature according to the state of the air just leaving the cooling media.According to the experimental results, the non-uniform temperature changes were observed along the greenhouses for the two systems. The average temperatures of the CU greenhouse were 27.9, 30.4, 33.2, 29.1 and 27.9 o C for outside ambient temperatures of 28.7, 32.4, 35.4, 32.1 and 29.4 o C, respectively. The ranges of temperature gradient inside the CU greenhouse were 2.1, 2.1, 2.2, 2.2, and 2.1 o C. While in the F-P greenhouse, they were 5.9, 7.4, 8.2, 5.9 and 6.1 o C for the same ambient temperatures. The average air temperature entering to greenhouse was approximately 6.82 and 7.09 ºC lower than the outside air temperature for CU and F-P systems. The greenhouse of CU system was higher in the relative humidity than F-P one. The average relative humidities were 69.0 and 61.8% for the CU and F-P greenhouses, respectively, with increase percent 12.38%. The averages CU efficiencies were 77.55% and 74.79% in the first and second days, respectively, while they were 72.97% and 70.19% for the same days for F-P system. Consequently, the CU system was averagely more efficient than the F-P system by 6.29% and 6.58%. The water flow rate of the two systems to permit optimum wetness and air saturation were 5.6 and 6.5 L/min for the CU and F-P evaporative cooling systems, respectively. The saving percentage in water circulation was 16.1% for the CU system. The total yield per plant was 6.24 and 5.48 kg/plant for the CU and F-P systems, respectively. The CU system increased the yield per plant with 13.82% over the F-P system.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Improving Performance of the Evaporative Cooling System inside the Greenhouses and Its Effect on Tomato Productivity

G.D.M.

T.R.

Mostafa

2015

Alexandria Science Exchange Journal: An International Quarterly

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“…The closer temperature measured in front of pad inside greenhouse is to wetbulb temperature, higher cooling efficiency of pad. However, it is emphasized that the highest efficiency values can be produced at low air velocities (Franco et al 2014). As the air velocity decreases, the length of time that the air comes into contact with the water increases, also increasing the saturation of the air, consequently the saturation efficiency is higher (Franco et al 2010).…”

Section: Internal Conditionsmentioning

confidence: 99%

Performance Analysis of a Greenhouse Fan-Pad Cooling System: Gradients of Horizontal Temperature and Relative Humidity

Dayioğlu

Silleli²

2014

Tar. Bil. Der.

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An experimental study is conducted to determine the performance parameters of system, as well as gradients of temperature and humidity along greenhouse when opening Fan-Pad cooling system. Measurements in the study were carried out by using seven sensors for different locations, as well as portable instruments. For this purpose, the five digital temperature and humidity sensors and two pyranometers were used during experiments. Among them, two were located outside greenhouse for external measurements. The rest one pyranometer above the crop canopy, four temperature and humidity sensors were mounted within the crop canopy along the greenhouse. Four sensors were placed according to positions defined between pad and fan. According to the experiment results, the non-uniform temperature changes, but approximately uniform humidity changes due to the crop transpiration were observed along greenhouse from pad panels to exhaust fans. When the cooling system closed, hourly mean temperature and relative humidity from Pad to Fan inside greenhouse changed between 30-33 °C and 30-47%, respectively, at outside climate conditions of 32 °C and 25%. After providing stabile cooling by opening Fan-Pad system, hourly mean temperature and relative humidity along greenhouse from pad to fan ranged between 20 -27 °C, and 50 -68%, respectively. The air temperature entering to greenhouse with air velocity of 0.8-0.9 ms -1 through pad was approximately 12-13 ºC lower than the outside air temperature. The air temperature from Pad to Fan increased approximately by 7 ºC. The method of psychrometric calculations was employed to determine the cooling efficiency of Fan-Pad system. According to the calculation result, the average of air temperatures inside greenhouse was 24.5 ºC after achieving stable cooling for outside air temperature of 31.4 ºC. The hourly mean cooling effect and cooling efficiency calculated for Fan-Pad system were determined to be 6.96 ºC and 76.8%, respectively.

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Direct evaporative cooling from wetted surfaces: Challenges for a clean air conditioning solution

Tejero‐González

Franco-Salas

2021

WIREs Energy & Environment

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Evaporative cooling has a major role to play in fighting climate change and in achieving a low‐carbon economy. As it helps to reduce energy demand for air conditioning, it is gaining attention in terms of improving energy efficiency in buildings. Evaporative cooling from wetted media can enhance water–air contact, thereby improving heat and mass transfer further and avoiding aerosols. Wetted media are commonly called evaporative cooling pads and are widely used in greenhouses, intensive livestock farming, and industrial facilities. However, a deep understanding of evaporative cooling pad performance can enhance their application to indoor occupied spaces such as residential or commercial cooling, or in hybrid air conditioning systems. Most studies analyze pad performance mainly in terms of pressure drop and saturation effectiveness. However, some studies propose alternative cooling efficiency parameters and others provide insights into key aspects such as power requirements and the coefficient of performance, water consumption, risk of water entrainment, material decay, and air quality, as well as the effect of water temperature and salinity, solar radiation, or wind speed. Existing results on these less studied performance issues are reviewed, and we identify the gaps in the literature in addition to highlighting the main challenges encountered, in an effort to guide future researchers in the field and enhance the application of direct evaporative cooling. This article is categorized under: Energy Efficiency > Systems and Infrastructure Energy Systems Analysis > Systems and Infrastructure

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Energy Efficiency in Greenhouse Evaporative Cooling Techniques: Cooling Boxes versus Cellulose Pads

Cited by 74 publications

References 17 publications

Improving Performance of the Evaporative Cooling System inside the Greenhouses and Its Effect on Tomato Productivity

Improving Performance of the Evaporative Cooling System inside the Greenhouses and Its Effect on Tomato Productivity

Performance Analysis of a Greenhouse Fan-Pad Cooling System: Gradients of Horizontal Temperature and Relative Humidity

Direct evaporative cooling from wetted surfaces: Challenges for a clean air conditioning solution

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