Air Humidity Conditions Research Articles

NO2 sensing mechanism of ZnO–Eu2O3 binary oxide under humid air conditions

In order to understand the role of ambient humidity on NO2 detection, electrical resistance and work function changes were recorded simultaneously on ZnO–Eu2O3 material. Thus, surface band bending and electron affinity could be evaluated, according to the Schottky model. The lack of electron affinity changes during NO2 exposure in dry air conditions, reveals that only the free charge concentration is affected. Exposure to NO2 in humid background leads to an increase in sensor signals and a significant change in the electron affinity as well. This effect suggests an interaction between NO2 and surface hydroxyl species; thereby additional charge carriers are involved in the overall sensing process. High resolution XPS analysis proves the presence of Eu solely in the 3+ oxidation state before and after NO2 exposure. A gas-sensing interaction mechanism has been proposed.

Experimental research on the influence of the air humidity conditions in an air conditioning system

The factors that have influence on the energy consumption of a small air conditioning system that are worth mentioning are the efficiencies of the compressor, evaporator and condenser, the form that the refrigerant flow is controlled, the fan model used, and climatic conditions. Within the climate issue, an interesting factor is that the relative humidity when it comes to the effect that it causes, especially in the performance of the air condenser, which generally is not considered in the projects. This study aims to evaluate the influence of humidity on the coefficient of system performance (COP), seeking to quantify their influence when it happens. The tests were performed on a testing bench, mounted at the Laboratory for Energy Efficiency (LAMOTRIZ) UNESP-Campus Guaratinguetá. In the study, the wet bulb temperature was ranged, keeping the rotation of the scroll compressor with application of a frequency inverter in its best performance. The test bench is provided with a supervisory system of data collection that is also able to control all functions of the bench. In the results, there was a significant influence, particularly when comparing high humidity conditions with low humidity, noting that only over 65% relative humidity is that significant changes are observed in the COP of the system.

Resfriamento artificial na conservação da qualidade comercial de grãos de milho armazenados

O resfriamento artificial é uma ferramenta para conservação da qualidade de grãos nas regiões tropicais. Este trabalho foi realizado com o propósito de verificar o efeito da refrigeração artificial do ar, por meio de aeração, na preservação da qualidade de grãos de milho em armazém graneleiro horizontal, de fundo "V". Para o experimento foram utilizados dois septos, sendo um resfriado artificialmente (12ºC), com capacidade de 28 mil toneladas, e o outro aerado com ar natural, com capacidade de 29 mil toneladas. As amostragens foram realizadas, em ambos os septos, durante a carga, aos 60 e 120 dias após a primeira etapa de resfriamento e durante a expedição dos grãos. Durante o armazenamento, as amostragens foram realizadas considerando-se a posição e a profundidade da massa de grãos de milho. A avaliação qualitativa consistiu na determinação dos seguintes parâmetros: peso de mil grãos, temperatura da massa de grãos, teor e acidez de óleo, identificação de fungos, teor de aflatoxina, índice de infestação de insetos e porcentagem de grãos infestados. O resfriamento artificial promoveu a diminuição da temperatura da massa de grãos, independentemente das condições de temperatura e umidade do ar externo. A aeração artificial, com ar frio, preservou os parâmetros atribuídos à qualidade dos grãos e proporcionou redução na percentagem de grãos infestados e na população de insetos-praga na massa do produto. Assim, a utilização do resfriamento artificial no armazenamento de grãos de milho em regiões tropicais é eficaz na manutenção da qualidade dos grãos e no manejo de insetos e patógenos.

Dimensional Stability of Plywood Panels Made from Thermally Modified Poplar Veneers in the Conditions of Variable Air Humidity

ABSTRACT • Some properties of plywood panels made from untreated and thermally modified (90 min. at 200 oC) poplar veneers and their combinations have been analyzed. The change in equilibrium moisture content and the change in dimensions of the samples conditioned above water in closed containers were examined. The analysis using F-test (ANOVA) at the significance level of 95% confirmed that, regarding moisture content, all combinations of plywood panels differed significantly from the control panels. However, the analysis of thickness swelling showed that there was no significant difference among the plywood panels of similar construction. The highest values of anti-swelling efficiency were shown by plywood panels made from thermally modified veneers.

Graft-take Success in Walnut Under Controlled Conditions and Plant Development in the Nursery

The production of walnut nursery plants is a complex process, being dependent upon a range of factors that affect graft-take success and behaviour of walnut plants in the nursery. The experiment included two parts. Three different treatments were used in the heated room under controlled air temperature and humidity conditions: Treatment 1-grafting without paraffin treatment of the scion and graft union, coupled with covering the graft with sawdust up to the top of the scion; Treatment 2-grafting involving paraffin treatment of the scion and graft union, coupled with covering the graft with sawdust up to the top of the scion; and Treatment 3-grafting involving paraffin treatment of the scion and graft union, coupled with covering the graft with both sawdust up to the top of the scion and polyethylene foil. The treatments were evaluated for their effect on graft-take success. Graft planting in the nursery was followed by two treatments: treatment without foliar fertilisation and treatment with foliar fertilisation. Under controlled conditions, treatment 3 induced a higher graft-take success as compared to the other two treatments, whereas foliar fertilisation in the nursery had a positive effect on the survival, production of class 1 plants and vegetative growth of walnut plants.

A moderna cafeicultura dos cerrados brasileiros

The Brazilian coffee planting presents a great importance in the creation of job opportunities, resources, and exchange value, being very diversified, with local particularities. The Brazilian Savannah covers more than 200 million ha, distributed along the States of Minas Gerais, Goias, Mato Grosso, Mato Grosso do Sul, Tocantins, Bahia, Piaui, Maranhao, and Distrito Federal, and has reached a yield of more than 5 million bags per year, mainly for Coffea arabica L. The coffee growing, in that region, stands out for presenting yield above the national average and for using, in a more efficient way, agricultural inputs, irrigation, improved varieties, and mechanization, among other practices. The irrigated coffee crop, in Brazil, covers 240,000 ha, most of these in the Brazilian Savannah, representing 10% of the total planted area and 25% of the total coffee yield. The most used irrigation systems are the sprinkler ones (conventional, net sprinkler, and center pivot) and the located ones (dripping and modified). Its climate favours coffee quality, as it allows harvesting under low air humidity conditions, since rainfall is concentrated in the summer. It is also observed, in the Brazilian Savannah areas, higher insolation rates, mainly in the autumn and winter months, favorable to yield and quality. The most planted varieties are the Catuai and Mundo Novo ones, along with other promising drought and diseases resistant materials.

Effect of thin hydrophobic films for toluene adsorption and desorption behavior on activated carbon fiber under dry and humid conditions

The toluene adsorption and desorption behavior of bare activated carbon fibers (ACFs) and those with a thin hydrophobic coating were studied. ACF surfaces were made hydrophobic by evaporating polydimethylsiloxane (PDMS) on AFCs under atmospheric pressure condition. In the breakthrough curve of bare-ACF for toluene under humid air condition, the roll-up phenomenon towards toluene adsorption was observed. This was attributed to the substitution of the adsorbed toluene by water on ACF, leading to a rise of outlet concentration above the inlet concentration with a decrease in the amount of adsorbed toluene. Compared to bare-ACF, a superior selectivity and adsorption capacity for toluene was observed on the ACFs coated with PDMS. It is suggested that the PDMS-coating can increase the removal efficiency of ACF for toluene under humid air condition.

SEARCH FOR JUGLANS REGIA GENOTYPES RESISTANT/TOLERANT TO XANTHOMONAS ARBORICOLA pv. JUGLANDIS IN THE FRAMEWORK OF COST ACTION 873

Walnut blight, caused by Xanthomonas arboricola pv. juglandis (Xaj), is the most important disease of English walnuts (Juglans regia L.). Infections occur also on other Juglans species and inter-specific hybrids. With the aim of reporting the outputs of the Working Group ‘Genetic Resources’ of COST Action 873 on Xaj resistance/ tolerance of English walnut, the results of trials produced by this and other groups are illustrated and discussed in this paper. Methods of infection, descriptions of Xaj damages in leaves, and results of open field and laboratory tests are reported. The content of phenolic compounds of leaves and green fruits, and its relationship with tolerance/susceptibility, as well with host protection mechanisms against Xaj infection, are commented. Results show that a final and simple way for obtaining J. regia materials resistant to Xaj is not available. However, it looks like possible to find genotypes tolerant to Xaj out of native J. regia population where air temperature and humidity conditions favour the spreading of this bacterium.

Bryophyte cover on trees as proxy for air humidity in the tropics

Climatic conditions are a prime candidate to explain local patterns of biodiversity and consequently there is great need of on-site climatic measurements. Among them, however, air humidity is notoriously difficult and time-consuming to measure, and it has been proposed that the epiphytic bryophyte cover can be used as an indicator of long-term air humidity conditions. Here we explore the utility of visually estimated epiphytic bryophyte cover on large canopy branches as a proxy for air humidity at 26 study sites in tropical forests where we measured microclimate for at least 12 months. Across all sites, bryophyte cover was weakly related to relative air humidity (R2=0.17), but when we separated highland (1800–3500m elevation) from lowland (<1800m) sites, relative air humidity showed significant and distinct relations to bryophyte cover (R2=0.36–0.62), whereas temperature was related to bryophyte cover only in the lowlands (R2=0.36). We conclude that epiphytic bryophyte cover can be used as a proxy for air humidity if temperature and elevation are taken into account within a circumscribed study region, but might not be applicable for comparisons across extensive elevational gradients or wide differences in temperature.

Performance study of a constant temperature and humidity air-conditioning system with temperature and humidity independent control device

To reduce the large energy penalty for constant temperature and humidity control in conventional air-conditioning systems, a novel temperature and humidity independent control (THIC) device is developed for typical cooling coils. The working principle of the THIC device is to adjust the chilled water flow rate in a cooling coil (CC) to maintain constant temperature and to adjust the apparatus dew point temperature of the CC to maintain constant humidity. A split-range control strategy is developed to control the cooling coil with the THIC device, the heater and the humidifier to achieve reliable control of indoor temperature and humidity while minimizing energy use.Control performance of the THIC device was tested in an existing constant temperature and humidity air conditioning system serving a storeroom in a museum. The field test shows that the indoor temperature and humidity were well controlled in the required range. Energy performance of the THIC was tested using simulation tests on TRNSYS platform. Seven testing cases with different typical load conditions were conducted. The energy performance of the THIC is compared with conventional air conditioning systems. The results show that the THIC device can achieve power saving of 30–50%.

Optimizing the distance for bacterial treatment using surface micro-discharge plasma

Reactive plasma species generated by a surface micro-discharge (SMD) electrode are delivered to the target by diffusion and/or convection. In humid air conditions, the diffusion process is coupled with complicated plasma chemical reactions, which affect the density profiles of bactericidal agents. One may expect that the production of reactive plasma species can be optimized at a certain distance. Our experimental results found the optimum distance for achieving the highest bactericidal efficiency with plasma treatment using an SMD electrode. The optimum distance is about 2–4 mm from the SMD electrode to the target and depends on the geometry of the experiment. The bactericidal efficiency in the plasma-treated area can be improved by a factor of 30 if the bacterial samples are placed at the optimum distance. The results show the predominant role of the long-lived reactive plasma species. It is seen that the diffusion model of multi-plasma species with coupled plasma chemical reactions would be highly important for understanding the bactericidal property of cold atmospheric plasmas and therefore for optimizing cold atmospheric plasma sources for medical and biological applications.

A case study of Asian dust storm particles: Chemical composition, reactivity to SO 2 and hygroscopic properties

Abstract Mineral dust comprises a great fraction of the global aerosol loading, but remains the largest uncertainty in predictions of the future climate due to its complexity in composition and physico-chemical properties. In this work, a case study characterizing Asian dust storm particles was conducted by multiple analysis methods, including SEM-EDS, XPS, FT-IR, BET, TPD/mass and Knudsen cell/mass. The morphology, elemental fraction, source distribution, true uptake coefficient for SO 2, and hygroscopic behavior were studied. The major components of Asian dust storm particles are aluminosilicate, SiO 2 and CaCO 3, with organic compounds and inorganic nitrate coated on the surface. It has a low reactivity towards SO 2 with a true uptake coefficient, 5.767×10 −6, which limits the conversion of SO 2 to sulfate during dust storm periods. The low reactivity also means that the heterogeneous reactions of SO 2 in both dry and humid air conditions have little effect on the hygroscopic behavior of the dust particles.

Water channel structure of bassanite at high air humidity: crystal structure of CaSO4·0.625H2O

Structure analysis using single-crystal diffraction was carried out as a contribution to the dispute about the nature of the water channel structure of bassanite (CaSO(4)·0.5H(2)O). A recent result of Weiss & Bräu (2009) for the crystal structure of bassanite (monoclinic, space group C2) at ambient conditions of air humidity was confirmed. In the presence of high relative air humidity the crystal structure of bassanite transformed due to the incorporation of additional water of hydration. The crystal structure of CaSO(4)·0.625H(2)O was solved by single-crystal diffraction at 298 K and 75% relative air humidity. The experimental results provided an insight into both crystal structures. A model explaining the phase transition from CaSO(4)·0.625H(2)O to CaSO(4)·0.5H(2)O was derived. The monoclinic cell setting of CaSO(4)·0.5H(2)O and the trigonal cell setting of CaSO(4)·0.625H(2)O were confirmed by powder diffraction.

Understanding Run-In Behavior of Diamond-Like Carbon Friction and Preventing Diamond-Like Carbon Wear in Humid Air

The friction behavior of diamond-like carbon (DLC) is very sensitive to the test environment. For hydrogen-rich DLC tested in dry argon and hydrogen, there was always an induction period, so-called "run-in" period, during which the friction coefficient was high and gradually decreased before DLC showed an ultralow friction coefficient (less than 0.01) behavior. Regardless of friction coefficients and hydrogen contents, small amounts of wear were observed in dry argon, hydrogen, oxygen, and humid argon environments. Surprisingly, there were no wear or rubbing scar on DLC surfaces tested in n-pentanol vapor conditions, although the friction coefficient was relatively high among the five test environments. Ex situ X-ray photoelectron and near-edge X-ray absorption fine-structure spectroscopy analyses failed to reveal any differences in chemical composition attributable to the environment dependence of DLC friction and wear. The failure of getting chemical information of oxygenated surface species from the ex situ analysis was found to be due to facile oxidation of the DLC surface upon exposure to air. The removal or wear of this surface oxide layer is responsible for the run-in behavior of DLC. It was discovered that the alcohol vapor can also prevent the oxidized DLC surface from wear in humid air conditions.

An Axial Flow Compressor for Operation With Humid Air and Water Injection

The first steps of the turbomachinery design usually rely on numerical tools based on inviscid formulation with corrections using loss models to account for viscous effects, secondary flows, tip clearances, and shock waves. The viscous effects are accounted for using semi-empirical correlations especially assembled for the chosen airfoils and range of operating conditions. Fast convergence and good accuracy are required from such design procedures. There are successful models that produce very accurate performance prediction. Among the methodologies commonly used, the streamline curvature (SLC) is used since those characteristics and the most important properties can be calculated reasonably well at any radial positions, assisting other more complex analysis programs. The SLC technique is, therefore, well suited for the design of axial flow compressors for reasons such as quick access to vital flow properties at the blade edges from which actions may be taken to improve its performance at the design stage. This work reports the association of a SLC computer program and commercial software for comparison purposes, as well as for grid generation required by a full 3D, turbulent Navier–Stokes computer program used for flow calculation in the blade passages. Application to a high performance three-stage axial flow compressor with inlet guide vane demonstrates the methodology adopted. The SLC program is also capable of calculating the compressor performance with humid air and water injection at any axial position along the compressor. The influence of water injection at different axial positions, water particle diameter, and temperature of water particles were studied for different humid air conditions. The positions of the evaporating water particles were calculated using their thermophysical and dynamic properties along the compressor.

Adsorption phenomena in photocatalytic reactions: The case of toluene, acetone and heptane

Nowadays, with the increase in the thermal insulation of buildings, indoor air quality (IAQ) has deteriorated, particularly because of the presence of volatile organic compounds (VOC). To improve IAQ, photocatalytic processes can be used. Photocatalytic reactions can be broken down into three steps: adsorption of pollutants, chemical reaction, and desorption of water, carbon dioxide and by-products. In this work, the accessibility of the pollutants to the reactive sites of a commercial TiO 2-photocatalyst is studied. Firstly, adsorption mechanisms are investigated through toluene adsorption isotherms in batch reactors. In humid air conditions (relative humidity of 50% at 24 °C), the classical adsorption models cannot be applied. Consequently, a new model, called the “Langmuir-multi”, is built. It fits the obtained experimental data properly. Adsorption equilibrium constants are calculated based on this new model. To understand adsorption mechanisms better, adsorption isotherms are also performed in dry air conditions with toluene and in humid air with acetone and heptane. It is observed that water vapor plays a major role. Secondly, photocatalytic reactions are carried out with toluene, acetone and heptane in humid air. The kinetic curves are well-represented by the Langmuir–Hinshelwood (L–H) equation so that reaction and equilibrium constants can be assessed. The L–H equilibrium constant appears to depend on the type of pollutant and on the affinity between the pollutant and the photocatalyst surface. No correlation is found between the equilibrium constant and light intensity. It is also shown that the calculated L–H equilibrium constants are not equal to those previously obtained in dark conditions and in batch reactors.

Mathematical models to describe the volumetric shrinkage rate of red beans during drying

The present study aimed to determine the volumetric shrinkage rate of bean (Phaseolus vulgaris L.) seeds during air-drying under different conditions of air, temperature and relative humidity, and to adjust several mathematical models to the empiric values observed, and select the one that best represents the phenomenon. Six mathematical models were adjusted to the experimental values to represent the phenomenon. It was determined the degree of adjustment of each model from the value of the coefficient of determination, the behavior of the distribution of the residuals, and the magnitude of the average relative and estimated errors. The rate of volumetric shrinkage that occurred in bean seeds during drying is between 25 and 37%. It basically depends on the final moisture content, regardless of the air conditions during drying. The Modified Bala &amp; Woods' model best represented the process.

Study on Relationship between Mechanical Properties and Seam Smoothness Worsted Fabric

The instability of seam smoothness for worsted fabric is always a big problem in suit industry. With substantial development and application of new worsted fabric as well as the comprehensive application of various fiber materials，it is difficult to control seam smoothness of suit, creating the quality of suite to descend and adversely affecting the brand development in suit industry. The purpose of this paper is, therefore, intending to study the relationship between worsted fabric mechanical properties and garment seam smoothness grade as well as the effect of environmental air temperature and humidity conditions on smoothness of seam sample, by selecting several pieces of worsted fabrics and testing their mechanical properties through FAST. The goal of this paper is to facilitate textile and garment enterprises to improve their own textile process and finishing as well as the sewability of worsted fabrics.

Detection distance and environmental factors in conservation detection dog surveys

AbstractSurveys using conservation detection dogs have grown increasingly popular as an efficient means to gather monitoring data, particularly for elusive and low‐density species such as carnivores. Working with dogs can greatly increase the area surveyed for wildlife and the detection rate of survey targets. Due to the confounding effects of scent dispersion and dog movement, however, it can be difficult to estimate the area searched in a survey. Additionally, although detection dogs have been used in studies under a wide range of air temperature, humidity, and wind conditions, little research has examined how environmental factors affect detection dogs' effectiveness for wildlife surveys. Between 2003 and 2005, we trained 2 dogs to assist us with surveys for mammalian carnivore scats in northern California. We conducted controlled search trials to assess how the dogs' scat detection rates were affected by the distance of scats from the transect search line, as well as variation in six environmental factors. Both dogs detected &gt;75% of scats located within 10 m, and the dogs' detection rates decreased with increasing distance of scats from the transect line. Among environmental factors, precipitation was the most important variable explaining variation in scat detection rates for both dogs. Precipitation likely degrades or removes scats from the landscape over time, and detection rates increase as scat begins to accumulate following the last substantial (&gt;5 mm) rain event of the year. If scat accumulation is not controlled for in ecosystems with a strong seasonal pattern of rainfall, it could lead to considerable bias in study results. We recommend that researchers report the conditions under which conservation detection dog surveys took place and analyze how detection rates vary as a function of distance, temperature, precipitation, humidity, wind, and other locally important environmental factors. © 2010 The Wildlife Society.

Short-term CO2(g) exchange between a shallow karstic cavity and the external atmosphere during summer: Role of the surface soil layer

Abstract This study tests the hypothesis that the degree of moisture in the soil pore system determines gas exchange processes (ventilation/charge) between the outer atmosphere and the karst-epikarst during the warm, dry period (summer). These processes explain “anomalous” CO 2 fluxes measured over this and other ecosystems. Emission of CO 2 by ventilation of cavities requires an open double membrane system (host rock and soil) through which air movement can take place (H 2 O vapour , CO 2 , 222 Rn, etc.). An experimental study on the behavior of the soil and host rock porous system under changing air humidity conditions, coupled with a broad analytical approach addressing CO 2 fluxes using the eddy-covariance technique and monitoring of the cave microclimate serves to define the suitable environmental conditions favoring air transfer between the cave atmosphere and exterior. This study shows the correlation between evapotranspiration, CO 2 emissions, and cave ventilation processes due to the daytime opening of the soil membrane. Thus, the role of the soil as a membrane/interface or transfer medium can be observed, and it is directly dependent on weather conditions (temperature, humidity, wind).