Sonic anemometry to evaluate airflow characteristics and temperature distribution in empty Mediterranean greenhouses equipped with pad–fan and fog systems

López, Alejandro López; Valera, D.L.; Molina-Aiz, F.D.; Peña, Araceli

doi:10.1016/j.biosystemseng.2012.09.006

Cited by 51 publications

(29 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Our results are consistent with findings of past studies by Kittas et al (2001Kittas et al ( , 2003; Bartzanas & Kittas (2005); Al-Helal et al (2006); Teitel et al (2010); Lopez et al (2012) related to the temperature and humidity distributions. For example, in a study performed by (26 Ağustos 2009);Sensör konumları: 1, dış;2, pad;3, pade yakın;4, orta;5, fana yakın (26 Ağustos 2009);Sensör konumları: 1, dış;2, pad;3, pade yakın;4, orta;5, fana yakın Bartzanas & Kittas (2005), the difference between the air temperature entering to greenhouse and outside air temperature was about 10 °C.…”

Section: Internal Conditionssupporting

confidence: 94%

“…It was observed that the cooled air temperature levels passing the wet pad with air velocity of 0.8-0.9 m s -1 were approximately 12-13 °C lower than the outside air temperature. The maximum air velocity measured in front of Pads inside of the greenhouse was 0.9 m s -1 , but as moving away from Pads, it was observed that the air velocities reduced up to 0.2 -0.3 m s -1 in crop rows, which were also consistent with results obtained by Li & Willits (2008); Lopez et al (2012). ASABE (2008) has recommended the mean air velocity of 1.27 m s -1 entering to the greenhouse through the pad.…”

Section: Internal Conditionssupporting

confidence: 91%

“…For example, in a study performed by (26 Ağustos 2009);Sensör konumları: 1, dış;2, pad;3, pade yakın;4, orta;5, fana yakın (26 Ağustos 2009);Sensör konumları: 1, dış;2, pad;3, pade yakın;4, orta;5, fana yakın Bartzanas & Kittas (2005), the difference between the air temperature entering to greenhouse and outside air temperature was about 10 °C. In a research study carried out in a greenhouse equipped with Fan-Pad system by Lopez et al (2012), the inside air temperature was cooler up to 11.6 °C than that of a natural ventilated greenhouse. However, it is emphasized that the main drawback of the Fan-Pad system was the horizontal temperature gradients to be with a maximum difference of 11.4 °C between the pads and fans.…”

Section: Internal Conditionsmentioning

confidence: 99%

See 2 more Smart Citations

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

Dayioğlu

Silleli²

2014

Tar. Bil. Der.

View full text Add to dashboard Cite

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.

show abstract

Section: Internal Conditionssupporting

confidence: 94%

Section: Internal Conditionssupporting

confidence: 91%

Section: Internal Conditionsmentioning

confidence: 99%

See 1 more Smart Citation

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

Dayioğlu

Silleli²

2014

Tar. Bil. Der.

View full text Add to dashboard Cite

show abstract

“…High-temperature gradients of this type can markedly affect plant growth, and growers often combine cooling pads with shading, (Kittas, et al, 2003). The air saturation efficiency of the pad-fan system is greater than that of the fog system (Katsoulas et al, 2009); it is also cheaper (Sethi and Sharma, 2007a) and it consumes less water and energy (López et al, 2012). However, it requires extremely airtight greenhouse structures to ensure that all incoming air passes through the evaporative pads along part or the whole of the side wall, with powerful extractor fans being placed along the opposite wall to provide the required suction.…”

Section: Introductionmentioning

confidence: 99%

“…Experiments in a greenhouse integrated with the ground heat storing system were conducted to evaluate the effectiveness of the control system. According to López et al, (2012) in a greenhouse equipped with evaporative pads a difference in temperature of up to 11.6 °C was recorded with respect to a naturally ventilated greenhouse, whereas using the fog system this difference was 10.4 °C. The main drawback of the pad-fan system was the horizontal temperature gradients, with a maximum difference of 11.4 °C between the pads and the fans.…”

Section: Introductionmentioning

confidence: 99%

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

View full text Add to dashboard Cite

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.

show abstract

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

Tejero‐González

Franco-Salas

2021

WIREs Energy & Environment

View full text Add to dashboard Cite

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

show abstract

Sonic anemometry to evaluate airflow characteristics and temperature distribution in empty Mediterranean greenhouses equipped with pad–fan and fog systems

Cited by 51 publications

References 35 publications

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

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

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

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

Contact Info

Product

Resources

About