scholarly journals Enhanced Climate Control of Semi-arid and Arid Greenhouses Equipped with Fogging Systems

2012 ◽  
Author(s):  
Raphael Linker ◽  
Murat Kacira ◽  
Avraham Arbel ◽  
Gene Giacomelli ◽  
Chieri Kubota
Keyword(s):  
Relative Humidity ◽  
Air Temperature ◽  
Natural Ventilation ◽  
Agricultural Research ◽  
Tracking Error ◽  
Climate Control ◽  
Cooling Strategy ◽  
Temperature And Humidity ◽  
New Strategy ◽  
Semi Arid

The main objectives were (1) to develop, implement and validate control procedures that would make it possible to maintain year-round air temperature and humidity at levels suitable for crop cultivation in greenhouses operating in arid and semi-arid regions and (2) to investigate the influence of the operational flexibility of the fogging system on the performance of the system. With respect to the development of climate controllers, we developed a new control approach according to which ventilation is used to maintain the enthalpy of the greenhouse air and fogging is used to adjust the humidity ratio inside the greenhouse. This approach is suitable mostly for greenhouses equipped with mechanized ventilation, and in which the air exchange rate can be controlled with enough confidence. The development and initial validation of the controllers were performed in a small experimental greenhouses located at the Agricultural Research Organization and very good tracking were obtained for both air temperature and relative humidity (maximum mean deviations over a 10-min period with constant setpoints lower than 2.5oC and 5% relative humidity). The robust design approach used to develop the controllers made it possible to transfer successfully these controllers to a much larger semi-commercial greenhouse located in the much drier Arava region. After only minimal adjustments, which did not require lengthy dedicated experiments, satisfactory tracking of the temperature and humidity was achieved, with standard deviation of the tracking error lower than 1oC and 5% for temperature and relative humidity, respectively. These results should help promote the acceptance of modern techniques for designing greenhouse climate controllers, especially since given the large variety of greenhouse structures (shape, size, crop system), developing high performance site-specific controllers for each greenhouse is not feasible. In parallel to this work, a new cooling control strategy, which considers the contribution of humidification and cooling from the crop, was developed for greenhouses equipped with natural ventilation. Prior to the development of the cooling strategy itself, three evapotranspiration models were compared in terms of accuracy and reliability. The cooling strategy that has been developed controls the amount of fog introduced into the greenhouse as well as the percentage of vent openings based on the desired vapor pressure deficit (VPD) and enthalpy, respectively. Numerical simulations were used to compare the performance of the new strategy with a constant fogging rate strategy based on VPD, and on average, the new strategy saved 36% water and consumed 30% less electric energy. In addition, smaller air temperature and relative humidity fluctuations were achieved when using the new strategy. Finally, it was demonstrated that dynamically varying the fog rate and properly selecting the number of nozzles, yields additional water and electricity savings.

scholarly journals Thermal Performance of Single-Story Air-Welled Terraced House in Malaysia: A Field Measurement Approach

2020 ◽  
Vol 13 (1) ◽  
pp. 201
Author(s):  
Pau Chung Leng ◽  
Gabriel Hoh Teck Ling ◽  
Mohd Hamdan Ahmad ◽  
Dilshan Remaz Ossen ◽  
Eeydzah Aminudin ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Air Temperature ◽  
Thermal Performance ◽  
Field Measurement ◽  
Natural Ventilation ◽  
Residential Buildings ◽  
Wet Bulb Globe Temperature ◽  
Natural Lighting ◽  
Ventilation Performance ◽  
Globe Temperature

The provision requirement of 10% openings of the total floor area stated in the Uniform Building By-Law 1984 Malaysia is essential for natural lighting and ventilation purposes. However, focusing on natural ventilation, the effectiveness of thermal performance in landed residential buildings has never been empirically measured and proven, as most of the research emphasized simulation modeling lacking sufficient empirical validation. Therefore, this paper drawing on field measurement investigates natural ventilation performance in terraced housing with an air-well system. The key concern as to what extent the current air-well system serving as a ventilator is effective to provide better thermal performance is to be addressed. By adopting an existing single-story air-welled terrace house, indoor environmental conditions and thermal performance were monitored and measured using HOBO U12 air temperature and humidity, the HOBO U12 anemometer, and the Delta Ohm HD32.3 Wet Bulb Globe Temperature meter for a six-month duration. The results show that the air temperature of the air well ranged from 27.48 °C to 30.92 °C, with a mean relative humidity of 72.67% to 79.25%. The mean air temperature for a test room (single-sided ventilation room) ranged from 28.04 °C to 30.92 °C, with a relative humidity of 70.16% to 76.00%. These empirical findings are of importance, offering novel policy insights and suggestions. Since the minimum provision of 10% openings has been revealed to be less effective to provide desirable thermal performance and comfort, mandatory compliance with and the necessity of the bylaw requirement should be revisited.

INFLUENCE OF TEMPERATURE AND HUMIDITY ON THE EMERGENCE BEHAVIOUR OF ANAX JUNIUS (ODONATA: AESHNIDAE)

1973 ◽  
Vol 105 (7) ◽  
pp. 975-984 ◽  
Author(s):  
Robert Trottier
Keyword(s):  
Relative Humidity ◽  
Water Temperature ◽  
Air Temperature ◽  
Water Surface ◽  
Average Speed ◽  
Anax Junius ◽  
Air Temperatures ◽  
Stage 4 ◽  
Temperature And Humidity ◽  
Three Stages

AbstractEmergence from the water of Anax junius Drury normally occurred after sunset. The onset was affected independently by water temperature and air temperature; low water temperature and high air temperature delayed the onset of emergence. In the field, the net vrtical distance travelled above the water, before ecdysis, was positively correlated with air temperature. In the laboratory, the vertical distance travelled above the water was greatest when air and water temperatures were approximately the same. The average speed of climbing to the first resting position above the water surface was faster at high than low water temperature, but the average speed of climbing from there to the final position, where ecdysis occurred, was reduced due to the effects of air temperature and humidity. Air temperatures below 12.6 °C were found to retard ecdysis and larvae returned to the water and emerged early the following day making the final process of emergence and ecdysis diurnal instead of nocturnal. The duration of ecdysis was shorter at high than low air temperatures and only the first three stages, as arbitrarily defined, were longer at low than high relative humidity; stage 4, shortened with low relative humidity. This study shows that A. Junius, emerging from the water is affected at first by the temperature experienced when submerged, but it becomes gradually and cumulatively affected by air temperature and humidity while climbing to the ecdysial position and moulting.

scholarly journals ANALYSIS OF AIR TEMPERATURE AND HUMIDITY IN THE CAATINGA (SEMI-ARID) AREA OF BRAZIL: CONTRIBUTIONS TO THE RECOVERY, CONSERVATION, AND PRESERVATION OF THE BIOME

2019 ◽  
Vol 4 (4) ◽  
pp. 691-695
Author(s):  
Rebecca Luna Lucena ◽  
Cristiano Saulo de Morais ◽  
Aline Soares da Silva ◽  
Sara Fernandes de Souza ◽  
Magda Maria Guilhermino
Keyword(s):  
Air Temperature ◽  
Arid Area ◽  
Temperature And Humidity ◽  
Semi Arid

scholarly journals Quantifying the impact of heat on human physical work capacity; part II: the observed interaction of air velocity with temperature, humidity, sweat rate, and clothing is not captured by most heat stress indices

2021 ◽  
Author(s):  
Josh Foster ◽  
James W. Smallcombe ◽  
Simon Hodder ◽  
Ollie Jay ◽  
Andreas D. Flouris ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Empirical Study ◽  
Air Temperature ◽  
Physical Work ◽  
Climate Index ◽  
Physical Work Capacity ◽  
Air Movement ◽  
Wide Range ◽  
Temperature And Humidity ◽  
The Impact

Abstract Increasing air movement can alleviate or exacerbate occupational heat strain, but the impact is not well defined across a wide range of hot environments, with different clothing levels. Therefore, we combined a large empirical study with a physical model of human heat transfer to determine the climates where increased air movement (with electric fans) provides effective body cooling. The model allowed us to generate practical advice using a high-resolution matrix of temperature and humidity. The empirical study involved a total of 300 1-h work trials in a variety of environments (35, 40, 45, and 50 °C, with 20 up to 80% relative humidity) with and without simulated wind (3.5 vs 0.2 m∙s−1), and wearing either minimal clothing or a full body work coverall. Our data provides compelling evidence that the impact of fans is strongly determined by air temperature and humidity. When air temperature is ≥ 35 °C, fans are ineffective and potentially harmful when relative humidity is below 50%. Our simulated data also show the climates where high wind/fans are beneficial or harmful, considering heat acclimation, age, and wind speed. Using unified weather indices, the impact of air movement is well captured by the universal thermal climate index, but not by wet-bulb globe temperature and aspirated wet-bulb temperature. Overall, the data from this study can inform new guidance for major public and occupational health agencies, potentially maintaining health and productivity in a warming climate.

Thermocouple Psychrometer for Field Measurements

1951 ◽  
Vol 32 (6) ◽  
pp. 217-220 ◽  
Author(s):  
F. R. Bellaire ◽  
L. J. Anderson
Keyword(s):  
Air Temperature ◽  
Natural Ventilation ◽  
Field Measurements ◽  
Remote Locations ◽  
Thermocouple Psychrometer ◽  
Temperature And Humidity ◽  
Temperature Errors

A new thermocouple psychrometer, designed to indicate true air temperature and humidity in remote locations, is described. In order to minimize maintenance, it utilizes natural ventilation, but provides adequate shielding of sensing elements against radiation. Wet and dry bulb temperature errors of less than + 0.1C° are obtained in winds above 1 mph.

Temporal and Spatial Patterns of Temperature and Humidity in Taxodium distichum Shelterbelts of Jiangmen, South China

2012 ◽  
Vol 610-613 ◽  
pp. 1150-1154 ◽  
Author(s):  
Lu Zhang ◽  
Zhi Yao Su ◽  
Xiang Lin Wang
Keyword(s):  
Relative Humidity ◽  
Spatial Patterns ◽  
Air Temperature ◽  
Seasonal Pattern ◽  
Taxodium Distichum ◽  
Blank Field ◽  
Sugarcane Field ◽  
Temporal And Spatial Patterns ◽  
Temperature And Humidity ◽  
Temporal And Spatial

Temporal and spatial patterns of temperature and humidity in shelterbelts of Taxodium distichum were investigated using routine observation and gradient observation methods in sampling plots placed in Taxodium distichum shelterbelts, sugarcane, and open (blank) fields, respectively. The results showed that: 1) Taxodium distichum shelterbelts mitigated air temperature in July. Air temperature of Taxodium distichum shelterbelts was 0.7 °C and 1.7 °C lower than that of sugarcane field and blank field in July, respectively, while less change of air temperature in January was recorded. Air temperature at 20 cm from the ground in the Taxodium distichum shelterbelts was the highest in April, October and January, but the lowest in July; 2) Relative humidity in the Taxodium distichum shelterbelts was higher than in blank field through the four seasons, but lower than in sugarcane field in July, October and January. Relative humidity in sugarcane field and Taxodium distichum shelterbelts was higher near the ground, and relative humidity in sugarcane field increased significantly; 3) One-way ANOVA followed by Tukey’s HSD indicated that both air temperature and relative humidity were significantly different with a seasonal pattern among shelterbelts of Taxodium distichum, sugarcane field and open field (P＜0.001).

scholarly journals Effect of Lockdown,Temperature,and Humidity on the Pattern of COVID-19 in Erbil Province,Kurdistan Region, Iraq

2021 ◽  
Vol 20 (2) ◽  
pp. 56-67
Author(s):  
Rundk Hwaiz ◽  
◽  
Katan Ali ◽  
Namir Al-Tawil
Keyword(s):  
Relative Humidity ◽  
Air Temperature ◽  
Death Rate ◽  
Weather Conditions ◽  
World Health ◽  
The Novel ◽  
Number Of Patients ◽  
Temperature And Humidity ◽  
Novel Coronavirus ◽  
Health Organization

Background: COVID-19 was first reported in Erbil province in Iraq on March 19, 2020. The effect of lockdown on reducing the spread of the novel coronavirus and the effect of weather conditions (air temperature and humidity) on the daily reported number of cases and death rate of COVID-19 were investigated during April to July, 2020. Objective: To investigate the effect of lock down on reducing the spread of the novel coronavirus pandemic and the effect of weather conditions (air temperature and humidity) on the daily reported number of cases and death rate of COVID-19. Patients and Methods: The data collected during three different periods, the first (total lockdown), followed by the second period of lockdown relaxation, which was followed by the third period (interrupted relaxation of lockdown) that reported hundreds of new cases daily. The real-time PCR .assay was performed on suspected COVID-19 patients according to the protocol established by the World Health Organization. Results: Temperature and relative humidity were recorded in Erbil city in Iraq. Patients’ age ranged (2-70) years old. Out of (1469) patients confirmed positive with COVID-19, 57.7% of them were males, 31.3% were females, and the rest (11%) were children. The mean number of patients per day was 32.77 during the period of interrupted relaxation lockdown which was significantly higher than in the total-lock down period (3.88 patient), and the relaxation lockdown period (1.93 patient). The mortality rate per day was 0.77 during the period of interrupted relaxation lockdown was significantly higher than the rates (0.0%) of the other periods. Moreover, increasing the temperature increased the number of confirmed cases in July while, low relative humidity significantly increased the rate of reported cases. Conclusion: The increase in the number of reported cases of COVID-19, might be related to the interruption of lockdown. Moreover, the daily reported cases and mortality rates increased by increasing the temperature from April to June.

scholarly journals Lightning Behaviour during the COVID-19 Pandemic

F1000Research ◽  
2021 ◽  
Vol 10 ◽  
pp. 906
Author(s):  
Fazandra Yusfiandika ◽  
Chun Lim Siow ◽  
Chandima Gomes ◽  
Aravind Chockalingam ◽  
Lee Cheng Pay
Keyword(s):  
Statistical Analysis ◽  
Relative Humidity ◽  
Air Temperature ◽  
Human Activities ◽  
Correlation Study ◽  
T Test ◽  
Lightning Strikes ◽  
Variation Trend ◽  
Temperature And Humidity ◽  
Atmospheric Changes

Background COVID-19 has drastically dampened human activities since early 2020. Studies have shown that this has resulted in changes in air temperature and humidity. Since lightning activities are dependent on air temperature and humidity, this study is conducted to evaluate the correlation between the intensity of lightning activities with the atmospheric changes, and investigates the changes, in lightning activities due to atmospheric changes during the COVID-19 pandemic. Methods The hypothesis was tested through a t-test and Pearson’s correlation study. The variation trend of lightning strikes count (LSC) in Europe and Oceania during the five months COVID-19 lockdown period (March – July) compared to the same period in the previous five years from 2015 to 2019 is investigated. Results Statistical analysis shows the LSC in Europe and Oceania during the lockdown period dropped significantly by more than 50% and 44% respectively compared to the same period in previous five years. Furthermore, LSC was found to be positively correlated with air temperature and relative humidity in Europe. However, in Oceania, LSC seems to be only positively correlated with air temperature but negatively correlated with relative humidity. Conclusions This study seems to suggest that lightning activities have significantly changed during this pandemic due to reduction in human activities.

Dehumidification Through Indirect Nighttime Ventilation

2001 ◽  
Author(s):  
Hussein Abaza ◽  
Yvan Beliveau ◽  
Jim Jones
Keyword(s):  
Relative Humidity ◽  
Natural Ventilation ◽  
Energy Savings ◽  
Passive Cooling ◽  
Cooling Load ◽  
Building Structure ◽  
Ventilation Strategy ◽  
Cooling Strategy ◽  
Simulation Results ◽  
Cool Night

Abstract Natural ventilation is an important passive cooling strategy. Using cool night air can cool the building structure and lower air conditions energy consumption. However, there are obstacles in using this cooling strategy, including high relative humidity, pollution, limitations in the thermal storage of the building, and low nighttime air temperature. This paper investigates energy savings by indirect ventilation to pre-cool buildings and reduces humidity. The nighttime ventilation strategy is based on optimizing the use of direct and indirect natural ventilation through an air-to-air heat exchanger. This strategy has been tested at the Beliveau House in Blacksburg, Virginia. Simulation results suggest that the indirect ventilation strategy at the Beliveau House reduces inside relative humidity on hot humid summer days by 20%, and the total summer cooling load by 38% when compared to the existing condition.

scholarly journals Influence of Courtyard Ventilation on Thermal Performance of Office Building in Hot-Humid Climate: A Case Study

2018 ◽  
Vol 34 ◽  
pp. 02053
Author(s):  
Esra’a Sh. Abbaas ◽  
Ala’eddin A. Saif ◽  
MAC Munaaim ◽  
Md. Azree Othuman Mydin
Keyword(s):  
Relative Humidity ◽  
Air Temperature ◽  
Thermal Performance ◽  
Natural Ventilation ◽  
Office Building ◽  
Humid Climate ◽  
Airborne Pollutants ◽  
Indoor Sources ◽  
Hot Humid Climate

The influence of courtyard on the thermal performance of Development Department office building in University Malaysia Perlis (UniMAP, Pauh Putra campus) is investigated through simulation study for the effect of ventilation on indoor air temperature and relative humidity of the building. The study is carried out using EnergyPlus simulator interface within OpenStudio and SketchUp plug in software to measure both of air temperature and relative humidity hourly on 21 April 2017 as a design day. The results show that the ventilation through the windows facing the courtyard has sufficient effect on reducing the air temperature compared to the ventilation through external windows since natural ventilation is highly effective on driving the indoor warm air out to courtyard. In addition, the relative humidity is reduced due to ventilation since the courtyard has high ability to remove or dilute indoor airborne pollutants coming from indoor sources. This indicates that the presence of courtyard is highly influential on thermal performance of the building.

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