scholarly journals Towards a Sustainable Greenhouse: Review of Trends and Emerging Practices in Analysing Greenhouse Ventilation Requirements to Sustain Maximum Agricultural Yield

2020 ◽  
Vol 12 (7) ◽  
pp. 2794 ◽  
Author(s):  
Mohammad Akrami ◽  
Alaa H. Salah ◽  
Akbar A. Javadi ◽  
Hassan E.S. Fath ◽  
Matthew J. Hassanein ◽  
...  
Keyword(s):  
Water Scarcity ◽  
Fruits And Vegetables ◽  
Warm Season ◽  
Weather Conditions ◽  
High Solar Radiation ◽  
Solar Radiation Intensity ◽  
Adverse Influence ◽  
Agricultural Yield ◽  
Microclimate Conditions ◽  
Greenhouse Ventilation

Cultivation in open fields mainly depends on the location and time of farming, which itself highly depends on the quality and quantity of water for irrigation, weather conditions and soil characteristics. Water resources are highly dependent on the limited freshwater resources from the groundwater system, or rainwater. Countries in MENA (the Middle East and North Africa) rely mostly on desalination technologies for agriculture, due to water scarcity. Therefore, greenhouse (GH) agriculture can be developed to succeed in dealing with the water scarcity and provide sufficient sources of agricultural products as a sustainable solution. These indoor agriculture facilities, which are enclosed by transparent covers, can produce different sources of fruits and vegetables, using a controlled amount of water. By reducing the exchange rate of air with the outside environment, which is known as the confinement effects, greenhouses generate a suitable environment for the plants to grow under transparent covers to trap the sunlight. This raises the inside temperature above the maximum threshold levels, especially within the warm season, due to the high solar radiation intensity, having an adverse influence on the microclimate conditions and consequently the crop growth. In order to sustain maximum agricultural yield, greenhouse ventilation is an important parameter in which its trends and emerging practices were reviewed in this study.

scholarly journals Spatial variability and its scale dependency of observed and modeled soil moisture under different climate conditions

2012 ◽  
Vol 9 (9) ◽  
pp. 10245-10276 ◽  
Author(s):  
B. Li ◽  
M. Rodell
Keyword(s):  
Soil Moisture ◽  
Spatial Variability ◽  
Warm Season ◽  
Weather Conditions ◽  
Data Sets ◽  
Scale Dependency ◽  
Convex Shape ◽  
Climate Conditions ◽  
Spatial Moments

Abstract. Past studies on soil moisture spatial variability have been mainly conducted in catchment scales where soil moisture is often sampled over a short time period. Because of limited climate and weather conditions, the observed soil moisture often exhibited smaller dynamic ranges which prevented the complete revelation of soil moisture spatial variability as a function of mean soil moisture. In this study, spatial statistics (mean, spatial variability and skewness) of in situ soil moisture measurements (from a continuously monitored network across the US), modeled and satellite retrieved soil moisture obtained in a warm season (198 days) were examined at large extent scales (>100 km) over three different climate regions. The investigation on in situ measurements revealed that their spatial moments strongly depend on climates, with distinct mean, spatial variability and skewness observed in each climate zone. In addition, an upward convex shape, which was revealed in several smaller scale studies, was observed for the relationship between spatial variability of in situ soil moisture and its spatial mean across dry, intermediate, and wet climates. These climate specific features were vaguely or partially observable in modeled and satellite retrieved soil moisture estimates, which is attributed to the fact that these two data sets do not have climate specific and seasonal sensitive mean soil moisture values, in addition to lack of dynamic ranges. From the point measurements to satellite retrievals, soil moisture spatial variability decreased in each climate region. The three data sources all followed the power law in the scale dependency of spatial variability, with coarser resolution data showing stronger scale dependency than finer ones. The main findings from this study are: (1) the statistical distribution of soil moisture depends on spatial mean soil moisture values and thus need to be derived locally within any given area; (2) the boundedness of soil moisture plays a pivoting role in the dependency of soil moisture spatial variability/skewness on its mean (and thus climate conditions); (3) the scale dependency of soil moisture spatial variability changes with climate conditions.

scholarly journals Impacts of Microclimate Conditions on the Energy Performance of Buildings in Urban Areas

Buildings ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 189 ◽  
Author(s):  
Javanroodi ◽  
M.Nik
Keyword(s):  
Urban Areas ◽  
Energy Demand ◽  
Weather Conditions ◽  
Energy Performance ◽  
Urban Morphology ◽  
Weather Data ◽  
Architectural Form ◽  
Energy Performance Of Buildings ◽  
Microclimate Conditions ◽  
The Impact

Urbanization trends have changed the morphology of cities in the past decades. Complex urban areas with wide variations in built density, layout typology, and architectural form have resulted in more complicated microclimate conditions. Microclimate conditions affect the energy performance of buildings and bioclimatic design strategies as well as a high number of engineering applications. However, commercial energy simulation engines that utilize widely-available mesoscale weather data tend to underestimate these impacts. These weather files, which represent typical weather conditions at a location, are mostly based on long-term metrological observations and fail to consider extreme conditions in their calculation. This paper aims to evaluate the impacts of hourly microclimate data in typical and extreme climate conditions on the energy performance of an office building in two different urban areas. Results showed that the urban morphology can reduce the wind speed by 27% and amplify air temperature by more than 14%. Using microclimate data, the calculated outside surface temperature, operating temperature and total energy demand of buildings were notably different to those obtained using typical regional climate model (RCM)–climate data or available weather files (Typical Meteorological Year or TMY), i.e., by 61%, 7%, and 21%, respectively. The difference in the hourly peak demand during extreme weather conditions was around 13%. The impact of urban density and the final height of buildings on the results are discussed at the end of the paper.

scholarly journals A Zero-Liquid Discharge Model for a Transient Solar-Powered Desalination System for Greenhouse

Water ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1440 ◽  
Author(s):  
Mohammad Akrami ◽  
Alaa Salah ◽  
Mahdieh Dibaj ◽  
Maxime Porcheron ◽  
Akbar Javadi ◽  
...  
Keyword(s):  
Rainwater Harvesting ◽  
Weather Conditions ◽  
Maximum Amount ◽  
Distilled Water ◽  
Solar Still ◽  
Discharge System ◽  
Sustainable Technologies ◽  
Solar Radiation Intensity ◽  
Liquid Discharge ◽  
The Uk

The need for sustainable desalination arises from fast-occurring global warming and intensifying droughts due to increasing temperatures, particularly in the Middle East and North African (MENA) regions. Lack of water resources has meant that the countries in these regions have had to desalinate seawater through different sustainable technologies for food supplies and agricultural products. Greenhouses (GH) are used to protect crops from harsh climates, creating a controlled environment requiring less water. In order to have a sustainable resilient GH, a zero-liquid-discharge system (ZLD) was developed by using solar still (SS) desalination techniques, humidification-dehumidification (HDH), and rainwater harvesting. An experiment was designed and carried out by designing and manufacturing a wick type solar still, together with an HDH system, implemented into a GH. Using a pyrometer, the solar intensity was recorded, while the microclimate conditions (temperature and relative humidity) of the GH were also monitored. The GH model was tested in the UK and was shown to be a successful standalone model, providing its water requirements. In the UK, for one solar still with a surface area of 0.72 m2, maximum amount of 58 mL of distilled water was achieved per day. In Egypt, a maximum amount of 1090 mL water was collected per day, from each solar still. This difference is mainly due to the differences in the solar radiation intensity and duration in addition to the temperature variance. While dehumidification generated 7 L of distilled water, rainwater harvesting was added as another solution to the greenhouse in the UK, harvested a maximum of 7 L per day from one side (half the area of the greenhouse roof). This helped to compensate for the less distilled water from the solar stills. The results for the developed greenhouses showed how GHs in countries with different weather conditions could be standalone systems for their agricultural water requirement.

Honey Mesquite Canopy Responses to Single Winter Fires: Relation to Herbaceous Fuel, Weather and Fire Temperature

1998 ◽  
Vol 8 (4) ◽  
pp. 241 ◽  
Author(s):  
RJ Ansley ◽  
DL Jones ◽  
TR Tunnell ◽  
BA Kramp ◽  
PW Jacoby
Keyword(s):  
Moisture Content ◽  
Warm Season ◽  
Ground Level ◽  
Weather Conditions ◽  
Fuel Moisture ◽  
Fire Temperature ◽  
A Site ◽  
Fuel Moisture Content ◽  
Honey Mesquite ◽  
Warm Season Grasses

Honey mesquite (Prosopis glandulosa Torr.) canopy responses to fire were measured following 20 single winter fires conducted in north Texas. Weather conditions during the fires, understory herbaceous fine fuel (fine fuel) amount and moisture content, fire temperature at 0 cm, 10-30 cm and 1-3 m above ground, and canopy responses were compared. Ten fires occurred on a site where fine fuel was a mixture of cool and warm season grasses (mixed site). The other 10 fires occurred on a site dominated by warm season grasses (warm site). When both sites were included in regressions, peak fire temperature at all heights was positively related to fine fuel amount. Fine fuel amount, fine fuel moisture content, air temperature (AT) and relative humidity (RH) affected fire temperature duration in seconds over 100°C (FTD100) at 1-3 m height, but not at ground level. Mesquite percent above-ground mortality (topkill) increased with increasing fine fuel amount, decreasing fuel moisture content, increasing AT, and decreasing RH. Percent foliage remaining on non-topkilled (NTK) trees was inversely related to fine fuel amount and AT, and positively related to fine fuel moisture content. Effect of fire on mesquite topkill and foliage remaining of NTK trees was strongly affected by RH at the warm site (r2 = 0.92 and 0.82, respectively), but not at the mixed site. This difference was due to RH affecting fuel moisture content (and subsequently fire behavior) to a greater degree at the warm than at the mixed site, because of the lower green tissue content in warm site grasses at the time of burning. Under adequate fine fuel amounts to carry a fire, mesquite canopy responses to fire (i.e., topkill vs, partial canopy defoliation) were largely determined by AT and RH conditions during the fire. This has implications if the management goal is to preserve the mesquite overstory for a savanna result instead of topkilling all trees. Two substudies were conducted during 3 of the fires. Substudy 1 determined mesquite response to fire in 2 plots with different understory herbaceous fuel loads (5,759 vs. 2,547 kg/ha) that were burned under under similar weather conditions. Mesquite topkill was 81% and 11% in the high and low fuel fires, respectively. Under similar weather conditions, fine fuel was an important factor in affecting mesquite responses to fire. However, as demonstrated in the main study, under a variety of weather conditions, AT and RH influenced mesquite response to fire as much or more than did fine fuel. Substudy 2 compared response of mesquite plants with abundant and dry subcanopy fine fuel (3252 kg/ha; fuel moisture 10.4%), or sparse and green subcanopy fuel (1155 kg/ha; fuel moisture 25.9%) to a high intensity fire. All trees were topkilled, including those with low subcanopy fuel, probably from convection heat generated from herbaceous fuel in interspaces between trees. In support of this conclusion, thermocouple data from all 20 fires indicated that canopy responses were more related to fire temperature at 1-3 m than at lower heights. This suggests that the topkill mechanism was due to convective heat within the canopy rather than a girdling effect of fire at stem bases.

scholarly journals Seasonal and Diurnal Variations in Aerosol Concentration on Whistler Mountain: Boundary Layer Influence and Synoptic-Scale Controls

2011 ◽  
Vol 50 (11) ◽  
pp. 2210-2222 ◽  
Author(s):  
John P. Gallagher ◽  
Ian G. McKendry ◽  
Anne Marie Macdonald ◽  
W. Richard Leaitch
Keyword(s):  
Boundary Layer ◽  
Meteorological Data ◽  
Warm Season ◽  
Weather Conditions ◽  
Careful Analysis ◽  
Median Number ◽  
Synoptic Scale ◽  
Mixing Processes ◽  
Air Masses ◽  
Seasonal And Diurnal Variations

AbstractA mountain air chemistry observatory has been operational on the summit of Whistler Mountain in British Columbia, Canada, since 2002. A 1-yr dataset of condensation nuclei (CN) concentration from this site has been analyzed along with corresponding meteorological data to assess the frequency and patterns of influence from the planetary boundary layer (PBL). Characterization of air masses sampled from the site as either PBL influenced or representative of the free troposphere (FT) is important to subsequent analysis of the chemistry data. Median CN concentrations and seasonal trends were found to be comparable to other midlatitude mountain sites. Monthly median number concentrations ranged from 120 cm−3 in January to 1601 cm−3 in July. Using well-defined diurnal cycles in CN concentration as an indicator of air arriving from nearby valleys, PBL influence was found to occur on a majority of days during spring and summer and less frequently in late autumn and winter. Days with PBL influence were usually associated with synoptic-scale weather patterns that were conducive to convective mixing processes. Although more common in the warm season, vertical mixing capable of transporting valley air to the mountaintop also occurred in February during a period of high pressure aloft. In contrast, an August case study indicated that the more stable character of marine air masses can at times keep the PBL below the summit on summer days. Considerable variability in the synoptic-scale weather conditions at Whistler means that careful analysis of available datasets must be made to discriminate FT from PBL periods at the observatory.

scholarly journals Optimization of building form and its fenestration in response to microclimate conditions of an urban area

2020 ◽  
Vol 172 ◽  
pp. 19002
Author(s):  
Kavan Javanroodi ◽  
Vahid M. Nik ◽  
Yuchen Yang
Keyword(s):  
Thermal Comfort ◽  
Urban Area ◽  
Urban Areas ◽  
Energy Demand ◽  
High Performance ◽  
Weather Conditions ◽  
Climate Data ◽  
Heating And Cooling ◽  
Building Form ◽  
Microclimate Conditions

Designing building form in urban areas is a complicated process that demands considering a high number of influencing parameters. On the other hand, there has been an increasing trend to design highly fenestrated building envelopes for office buildings to induce higher levels of natural lighting into the workspace. This paper presents a novel optimization framework to design high-performance building form and fenestration configuration considering the impacts of urban microclimate in typical and extreme weather conditions during a thirty-year period of climate data (2010-2039). In this regard, based on the introduced technique and algorithm, the annual energy demand and thermal comfort of over 8008 eligible form combinations with eight different fenestration configurations and seven different building orientation angels were analysed in a detailed urban area to find optimal design solutions in response to microclimate conditions. Results showed that adopting the framework, annual heating, and cooling demand can be reduced by 21% and 38% while maintaining thermal comfort by taking design-based decisions at the early stages of design.

scholarly journals Photocatalytic degradation of commercial acetaminophen: evaluation, modeling, and scaling-up of photoreactors

2021 ◽  
Author(s):  
Déyler Castilla-Caballero ◽  
Fiderman Machuca-Martínez ◽  
Ciro Bustillo-Lecompte ◽  
José Colina-Márquez
Keyword(s):  
Weather Conditions ◽  
Scaling Up ◽  
Pilot Scale ◽  
Plant Performance ◽  
Photon Absorption ◽  
Turbulent Regime ◽  
Emission Model ◽  
Solar Radiation Intensity ◽  
Initial Ph ◽  
Catalyst Load

In this work, the performance of a pilot-scale solar CPC reactor was evaluated for the degradation of commercial acetaminophen, using TiO2 P25 as a catalyst. The statistical Taguchi’s method was used to estimate the combination of initial pH and catalyst load while tackling the variability of the solar radiation intensity under tropical weather conditions through the estimation of the signal-to-noise ratios (S/N) of the controllable variables. Moreover, a kinetic law that included the explicit dependence on the local volumetric rate of photon absorption (LVRPA) was used. The radiant field was estimated by joining the Six Flux Model (SFM) with a solar emission model based on clarity index (KC), whereas the mass balance was coupled to the hydrodynamic equations, corresponding to the turbulent regime. For scaling-up purposes, the ratio of the total area-to-total-pollutant volume (AT/VT) was varied for observing the effect of this parameter on the overall plant performance. The Taguchi’s experimental design results showed that the best combination of initial pH and catalyst load was 9 and 0.6 g L−1, respectively. Also, full-scale plants would require far fewer ratios of AT/VT than for pilot or intermediate-scale ones. This information may be beneficial for reducing assembling costs of photocatalytic reactors scaling-up.

A three year study on the soil water availability at roadside trees in Hamburg, Germany

2020 ◽  
Author(s):  
Alexander Schütt ◽  
Alexander Gröngroeft ◽  
Selina Schaaf-Titel ◽  
Annette Eschenbach
Keyword(s):  
Ecosystem Services ◽  
Soil Water ◽  
Water Availability ◽  
Water Scarcity ◽  
Weather Conditions ◽  
Vegetation Period ◽  
Critical Value ◽  
Tree Planting ◽  
Soil Water Availability ◽  
Soil Sealing

<p>The benefit of urban roadside trees to provide ecosystem services and wellbeing of human in expanding and compacted cities gets more and more attention. For northern Germany it is predicted that climate change rises summer temperatures and that precipitation patterns shift to drier vegetation periods. In cities, those impacts will intensify water (soil sealing) and heat problems (urban heat island) even more. Furthermore, roadside trees have to deal with several specific site limitations like extreme soil compaction and soil sealing, low water infiltration rates, sandy and anthropogenic deposited substrates, and soil volume restrictions. The consequences for the trees are drought stress combined with reduced vitality and life expectancy.</p><p>Our research is based on soil water monitoring at 17 roadside plantation sites across the city of Hamburg.  We focus on the water availability of prepared planting soils and the development of the trees root systems. Sensors for soil water tension and soil temperature were installed in different soil areas of each site: topsoil, root ball, tree pit substrate, lateral space, and subsoil. The general goal of this study was to characterize the soil water availability at roadside planting pits during the first years after plantation (here: 2017, 2018 and 2019). Based on these results the long-term objective is to elaborate recommendations for the soil-related technology of future urban tree planting sites. The Creation of more suitable conditions in the planting site enhances roadside tree vitality and provides ecosystem services by the trees on a higher level.</p><p>The data analysis focused on two main aspects. First, the effect of weather conditions, especially  the extreme wet and dry vegetation periods, on the soil water availability in the tree pit. Second, the three-year temporal development of soil water distribution in the different soil areas within the planting pitafter plantation.</p><p>We found that soil water availability in the vegetation period (VP; April-October) at the investigated roadside plantation sites are highly correlated to weather conditions (air temperature (aT) and precipitation (P)). During a cold and wet VP (aT: 14,0 °C, P: 631 mm), soil tensions reached a critical value on average at 24 ± 18 days (11 ± 9 % of VP). In a hot and dry VP (aT: 16,0 °C, P: 222 mm), soil tensions reached a critical value on average at 115 ± 22 days (54 ± 10 % of VP).</p><p>Furthermore, the results showed that soil water scarcity in the first VP occurred mainly in the root ball, whereas during the second VP water scarcity developed in all soil areas within the planting site, except for the subsoil. Although the amount of precipitation during the last vegetation period was more than doubled compared to the second, the subsoil reached higher water tensions. This finding leads to the conclusion that root development after plantation took place from the root ball over the prepared planting soil into the surrounding soil within depths of up to 1 m.  </p>

Sign in / Sign up

Export Citation Format

Share Document