Air Humidity Levels Research Articles

Effect of headspace air conditions on total organic acids dissolved in transformer oil

The aim of this work was studying the effect of dissolved oxygen concentration, temperature and humidity level of headspace air on the acidification of insulation oil. The novelty is assessment and classification of those parameters based on the acidity level, induction time and the rate of oil acidifying. Two gas-washers containing insulation oil and deionised water were in contact with the bubbling streams of O2/N2 containing different humidity levels. The acidity of two phases was determined based on TAN number and pH values, respectively. The results revealed that O2/N2 weight ratio, insulator temperature and the level of air humidity control the acidity strength, the induction time of acid production and the rate of oil acidifying, respectively. Reduction of O2/N2 weight ratio in the headspace air decreased the level of the produced organic acids, while reduction of temperature extended the onset time of acid formation. [Received: July 31, 2020; Accepted: January 12, 2021]

Morphological Responses of a Light-Demanding Alstonia scholaris and a Shade-Tolerant Eusideroxylon zwageri to the Air Humidity and Light Intensity

The response of tropical trees to the change of light intensity has been reported to be varied among different species. Some reports argued that the growth was increasing parallel to the increasing of light intensity, but other reports mentioned that the sensitivity to the light intensity was depending on the species. Another environmental factor that has been scientifically proven to affect tree growth is humidity. While humidity itself also directly affected by the light intensity in the forest ecosystems. Therefore, it is possible that the growth pattern of trees under different light intensities is also affected by air humidity under the canopy. This research aimed to study the growth response of a light-demanding Alstonia scholaris and a shade-tolerant Eusideroxylon zwageri to the different levels of air humidity and light intensity. The experiment was conducted in Jambi, Indonesia from April to November 2019. The experiment was carried out using split plot design with factorial treatments. The main plot was the air humidity with three levels and the sub plots was light intensity with five levels. Four replicates were applied. In general, the A. scholaris tends to be more sensitive to the humidity and light intensity compared to E. zwageri. In particular, A. scholaris tends to be more sensitive to the light intensity while, E, zwageri is more sensitive to the humidity. However, there is also strong indication that the effects of light intensity to the growth, especially for A. scholaris, was affected by the humidity level.

Assessment of hygrothermal performance of hemp concrete compared to conventional building materials at overall building scale

The aim of this paper is to analyse the impact of hemp concrete on the overall hygrothermal behaviour of the building when it used as an infill layer in the envelope of wood-frame structures. Three wall configurations were considered in different climates. Then, a hygrothermal co-simulation approach was used to integrate the model of coupled heat and moisture transfer through multilayered walls in a dynamic thermal simulation tool for the building. The material properties which constitute the input parameters for the model were determined experimentally, according to the hygrothermal state of the material. The results showed that hemp concrete significantly reduces the energy consumption of the building and has better insulation properties than the two conventional building materials: brick and aerated concrete. This is justified by the good hygrothermal properties of this bio-based material, especially its high thermal resistance of 3.08 K.m2/W compared to 0.88 K.m2/W of brick and 2.28 K.m2/W of aerated concrete. In addition, for the three climates considered, the thermal comfort of the hemp concrete envelope is significantly improved. This material also allows stabilisation of relative humidity levels in the ambient air by naturally regulating the hygrometry, to ensure better ambience. The study shows that hemp concrete has interesting hygrothermal properties. Thus, this material can be used massively in the construction field in order to meet the requirements of the current standards which aim to reduce the energy and environmental impacts of dwelling and office building.

Local‐scale evaporation and water loss distribution in surface soil as related to near‐surface wind conditions and surface geometry

AbstractLocal (cm) scale water loss distribution and evaporation in soil with flat and furrowed surfaces as a function of near‐surface wind speed and wind direction was investigated. Four levels of average main wind speed (10 cm above furrow ridge summits, 0, 1, 3 and 5 m·s−1), three main wind directions (compared to the direction of the furrows, 0°, 45° and 90°) and two levels of relative air humidity (70% and 86%) were considered. Experiments were conducted under controlled (wind tunnel) conditions, using 50 cm diameter and 15 cm height soil samples. For furrowed samples, 6 cm high ridges with 12 cm distance between ridge tops were used. Resulting wind speed profiles above ridge tops were relatively similar (for the same main wind speed), regardless of wind direction, but differed greatly in the valleys between ridges depending on especially wind direction. Strong indication of standing eddies on the lee side of furrow ridges for wind directions ≥45° was found. Local evaporative water loss spatial distribution in furrowed soil, was strongly dependent on wind direction, while local evaporation rates depended strongly on main wind speed and relative humidity level. Significantly higher evaporative water losses were observed at the wind‐exposed ridge slopes (for wind directions ≥45°) compared to lee slopes.Highlights Local (cm) scale water loss in furrowed soil under windy conditions was investigated. Wind speed profiles between furrow ridges were strongly dependent on wind direction. Local water loss was significantly higher on windward slopes in furrowed soil. Local water loss spatial distribution was strongly dependent on wind direction.

Performance and Economic Investigation of Solar Regenerated Liquid Desiccant Room Air Conditioning Systems using Eco-Friendly Desiccants

Traditional air conditioning systems run on the vapor compression cycle, which utilizes electricity generated from fossil fuels, the reserves of which are fast depleting. Moreover, the refrigerants used in such systems have exacerbated ozone layer depletion and climate change. Liquid desiccant air conditioning (LDAC) systems appear as a favorable option in light of these drawbacks. This paper has developed the numerical model of an LDAC system using a dehumidifier that is internally cooled and has a finned coil. The study of this particular model has been limited in the past. The model has been validated against a reference study available in the literature. Moreover, the commonly used desiccant materials tend to be corrosive and detrimental to the air quality. Therefore, the feasibility of an ionic liquid (65% [Emim]OAc) and an organic salt solution (73% HCOOK) as desiccant materials has also been investigated in this paper. With the proposed scheme for room air conditioning, the air temperature and humidity levels within the range of comfort (21∘C, 53% R.H.) could be supplied to the conditioned space. Performance analysis revealed that the eco-friendly desiccants could achieve dehumidifier and regeneration effectiveness similar to that of the traditionally used corrosive salt solution of calcium chloride (CaCl2). Furthermore, the estimated dehumidifier efficiency of about 76% is found to be higher than that available in the previous studies. Economic analysis provides a comparison of total cost between the conventional and the novel desiccant air conditioning systems and also reveals HCOOK to be a more economical choice as desiccant material.

Thermal Analysis-Based Field Validation of the Deformation of a Recycled Base Course Made with Innovative Road Binder.

The deformation of the cold recycled mixture with foamed bitumen in a recycled base with an innovative three-component road binder and foamed bitumen is analysed. Numerical simulation results for the pavement constructed, based on laboratory test results, were verified against the data from the monitoring system installed on the road trial section. In addition, environmental effects, such as air temperature and humidity levels in the pavement structure layers, were considered. Thermal analyses were conducted to identify the thermal properties of the pavement materials under steady heat transfer rate. Determining temperature distribution in the road cross-section in combination with relaxation functions determined for individual pavement layers contributed to the high effectiveness of the numerical simulation of deformation and displacement in the recycled base and the entire pavement. The experimental method of identifying thermal properties allows a fast and satisfactory prediction of temperature distribution in the pavement cross-section.

Microclimatic Effects on the Preservation of Finds in the Visitor Centre of the Archaeological Site 1a Imperial Palace Sirmium

When an archaeological site is roofed over for the better display of the finds and more comfortable experience of the audience, the intervention undoubtedly changes the microclimatic conditions in the site. Although sudden changes in microclimatic factors are known to damage and/or destroy archaeological finds, their impact and its analysis are neglected in Serbia. There is no continuous monitoring and control of microclimatic conditions or their impact on architectural remains in archaeological sites. Accordingly, the values of microclimatic parameters of temperature and relative humidity and their daily oscillations are examined in this paper through microclimatic monitoring in the Visitor Center of the Archaeological Site 1a Imperial Palace Sirmium, which is a cultural asset of exceptional importance. Moreover, microbiological analyses determine the degree of contamination of architectural findings. The aim of this paper is to determine whether the microclimatic regime in the Visitor Center of the Archaeological Site 1a Imperial Palace Sirmium is in accordance with European standards and recommendations on optimal microclimatic conditions for the presentation and preservation of cultural heritage collections. The findings showed that during the phase of microclimatic monitoring (February–April 2021), air humidity was almost constantly above the levels set by standards and recommendations for museum collections (>60%). The highest levels of air humidity, amounting to 93%, were recorded in February, with daily oscillations of up to 30%; the lowest recorded temperature was 0.3 °C, with the maximum daily oscillations of 6 °C. Microbiological analysis revealed great diversity in the deterioration level of the finds, which can be attributed to the time lapse between the last conservation and the present. The comparative analysis of the results of microclimatic monitoring and microbiological analysis identified high levels of relative air humidity as the dominant factor in the increased microbiological contamination of the finds. It is also concluded that the continuous monitoring of the microclimatic parameters of temperature and relative humidity during the usage of the facility is necessary so as to enable sustainable presentation and preservation of findings.

Health Assessment and Indoor Environmental Quality in Multiple Romanian Rural Schools

The current study was realized in three schools located in regional Romania. The results of this article draw upon the diversity of school’s typologies analyzed: new, existing refurbished and old. The analysis was carried using answers given by 138 children to a survey that covered questions related to their learning environment and health problems. Children were asked to rank the perceived quality of several indoor environment parameters (IAQ, outdoor air quality, illumination, noise), the stressful and friendly nature of the schools, and their overall satisfaction. The survey was accompanied by experimental measurements of air temperature, humidity, noise and illuminance levels, CO2 concentration and dust particles. The most prevalent symptoms experienced at school were sneezes (34.1%), fatigue (18.9%), runny nose (14.5%), stuffed/blocked nose (11.6%), and headache (8.7%). Out of the five main health symptoms reported at school, the majority has been recorded in the renovated school.

The Bintan MOS development: contribution of ideas to realize Nusantara marine observation network

Several marine research have attempted to design a data observation system using Internet of Things (IoT). In the future, this system is predicted to become a necessity for marine researchers as a strategic technology to continuously access data. Therefore, this study provides information on the development and application of observation and data collection systems using IoT. The coastal weather and tidal data were obtained via the automatic coastal weather station and acoustic gauge respectively. Meanwhile, the various research activities commenced in July, 2018. In the first year, an operational observation system was developed, while comprehensive baseline data such as air temperature, humidity, wind speed, and sea surface level were also collected. This collection system is reliable, provides real-time data, and easily accessible with internet connection. Furthermore, the Bintan Marine Observation System (The Bintan MOS) is also suitable for other uses such as; monitoring water quality and marine mammals, as well as disaster mitigation. The adoption of this system by other sectors potentially conditions marine researchers for data exchange, to fully understand the fluctuations in coastal weather of Western and Eastern Indonesia as well as the tropical and sub-tropical marine weather. This study successfully developed the Bintan MOS, capable of providing reliable information both off-line and real-time.Keywords:Marine observation systemCoastal weatherTidalBintan

Recuperator Performance Assessment in Humidified Micro Gas Turbine Applications Using Experimental Data Extended With Preliminary Support Vector Regression Model Analysis

Abstract Cycle humidification applied to micro gas turbines (mGTs) offers a solution to overcome their limited operational flexibility in terms of variable electrical and thermal power production when used in a combined heat and power (CHP) application. Although the positive impact of this cycle humidification on the performance has already been proven numerically and experimentally, very detailed modeling of the system performance remains challenging, especially the determination of the recuperator effectiveness, which has the highest impact on the final cycle performance. Indeed, the recuperator performance depends strongly on the mass flow rate of the air stream and its humidification level, two parameters that are difficult to measure accurately. Accurate modeling of the recuperator performance under both dry and humidified conditions is thus essential for correct assessment of the potential of humidified mGT cycles in decentralized energy systems (DESs). In this paper, we present a detailed analysis of the recuperator performance under humidified conditions using averaged experimental data, extended with the application of a support vector regression (SVR) on a time series to improve noise-modeling of the output signal, and thus enhance the accuracy of the monitoring process. In a first step, the missing experimental parameters, air mass flow rate and humidity level, were obtained indirectly, using rotational speed, fuel flow rate, exhaust gas composition and pressure level measurements in combination with the compressor map. Despite the low accuracy, some general trends regarding the recuperator performance could be observed based on these experimental data, indicating that the recuperator, despite having an increased total exchanged heat flux, is actually too small to exploit the full potential of the humidification. In a second step, by means of the SVR model, a first attempt was made to improve the accuracy and reduce the scatter on the recuperator performance determination. The predicted results with the SVR indicated indeed a reduced scatter on the determinations of the air mass flow rate and the amount of introduced water, opening a pathway toward online recuperator performance prediction.

Impact of Relative Humidity on COVID-19 Incidence

Introduction: The issue of the influence of external factors such as meteorological conditions on the dynamics of the coronavirus pandemic is extremely relevant, since understanding of physical foundations of any process helps predict its results in specific conditions and, to a certain extent, manage it. Objective: In order to assess the effect of relative humidity on the incidence of COVID-19, we analyzed opinions of the international scientific community about the nature and degree of the influence of meteorological conditions on COVID-19 incidence rates in humans. Materials and methods: We developed an original method of determining the periods of time when the air humidity level influenced disease rates, establishing the lag and the power of influence of the relative air humidity on the infection process and course of the disease. To eliminate the effect of confounders on research results, we applied the author’s method of estimating the conditional incidence as the difference between the theoretical and observed rates. The article presents the results of analyzing the correlation between relative humidity and COVID-19 incidence rates in 19 regions of the Russian Federation. Without exception, all the equations contained two or three extrema of the incidence in time, at which air humidity had the greatest impact on its rates. We associate these extrema with the time of getting infected and the time of disease manifestation and they enable us to quantitatively predict the latent period of this infectious disease in different atmospheric conditions. Conclusion: The observed correlations demonstrate relative humidity levels posing higher and lower risks of getting infected with COVID-19 in various regions of the Russian Federation. By means of mathematical methods, we confirmed the hypothesis about the persistence of SARS-CoV-2 in the environment for more than two weeks.

Seasonality of acute kidney injury in a tertiary hospital academic center: an observational cohort study

BackgroundThe aim of our study was to describe seasonal trends of acute kidney injury (AKI) and its relationship with weather conditions in a hospitalized population.MethodsWe retrospectively collected demographic (age, sex), clinical (ICD-9-CM codes of diagnosis discharge) and laboratory data (creatinine values) from the inpatient population admitted to Fondazione Policlinico Universitario A. Gemelli IRCCS between January 2010 and December 2014 with inclusion of all patients ≥18 years with at least two values available for creatinine. The outcome of interest was AKI development, defined according to creatinine kinetics criteria. The exposures of interest were the months and seasons of the year; air temperature and humidity level were also evaluated. Log-binomial regression models adjusted for age, sex, eGFR, comorbidities, Charlson/Deyo index score, year of hospitalization were used to estimate risk ratios (RR) and 95% confidential intervals (CI).ResultsA total of 64,610 patients met the inclusion criteria. AKI occurred in 2864 (4.4%) hospital admissions. After full adjustment, winter period was associated with increased risk of AKI (RR 1.16, 95% CI 1.05, 1.29, p=0.003). Lower air temperature and higher humidity level were associated with risk of AKI, however in multivariable-adjusted models only higher humidity level showed a significant and independent association.ConclusionsAKI is one of the most common complications of hospitalized populations with a defined seasonal pattern and a significant increase in incidence during wintertime; weather conditions, particularly higher humidity level, are independent predictors of AKI and could partially justify the observed seasonal variations.

Effect of Increased Cabin Recirculation Airflow Fraction on Relative Humidity, CO2 and TVOC

In the CleanSky 2 ComAir study, subject tests were conducted in the Fraunhofer Flight Test Facility cabin mock-up. This mock-up consists of the front section of a former in-service A310 hosting up to 80 passengers. In 12 sessions the outdoor/recirculation airflow ratio was altered from today’s typically applied fractions to up to 88% recirculation fraction. This leads to increased relative humidity, carbon dioxide (CO2) and Total Volatile Organic Compounds (TVOC) levels in the cabin air, as the emissions by passengers become less diluted by outdoor, dry air. This paper describes the measured increase of relative humidity, CO2 and TVOC level in the cabin air for the different test conditions.

Two types of fog shapes above a cold evaporating liquid

When liquid nitrogen is poured into a mug, a mist forms above. This article explores the influence of air humidity on the cloud and the formation of these boundaries in a controlled environment. We have identified that both homogeneous and heterogeneous nucleations occur during their formation. We highlight two types of ice clouds that differ only in the level of air humidity. Indeed, there is a critical humidity level at which one goes from a banded cloud to another without lower limit, extending to the cold liquid. We argue that this critical humidity level is related to the nitrogen flux.

Effect of increased cabin recirculation airflow fraction on relative humidity, CO2 and TVOC

In the CleanSky 2 ComAir study, subject tests were conducted in the Fraunhofer Flight Test Facility cabin mock-up. This mock-up consists of the front section of a former in-service A310 hosting up to 80 passengers. In 12 sessions the outdoor/recirculation airflow ratio was altered from today’s typically applied fractions to up to 88% recirculation fraction. This leads to increased relative humidity, carbon dioxide (CO2) and Total Volatile Organic Compounds (TVOC) levels in the cabin air, as the emissions by passengers become less diluted by outdoor, dry air. This paper describes the measured increase of relative humidity, CO2 and TVOC level in the cabin air for the different test conditions.

Effect of headspace air conditions on total organic acids dissolved in transformer oil

The aim of this work was studying the effect of dissolved oxygen concentration, temperature and humidity level of headspace air on the acidification of insulation oil. The novelty is assessment and classification of those parameters based on the acidity level, induction time and the rate of oil acidifying. Two gas-washers containing insulation oil and deionised water were in contact with the bubbling streams of O2/N2 containing different humidity levels. The acidity of two phases was determined based on TAN number and pH values, respectively. The results revealed that O2/N2 weight ratio, insulator temperature and the level of air humidity control the acidity strength, the induction time of acid production and the rate of oil acidifying, respectively. Reduction of O2/N2 weight ratio in the headspace air decreased the level of the produced organic acids, while reduction of temperature extended the onset time of acid formation. [Received: July 31, 2020; Accepted: January 12, 2021]

Pontes térmicas em estruturas de concreto

A importância de considerar as pontes térmicas e seus impactos no cálculo de transmitância térmica é um assunto que tem sido discutido em regiões de clima com estação fria no Brasil. A presença de pontos vulneráveis no envelope do edifício pode ter consequências no desempenho térmico, além das implicações nas paredes e coberturas do edifício, como por exemplo a formação de fungos filamentosos. Várias normas e regulamentos tratam da temática. Esse estudo tem por objetivo discutir, por intermédio de simulação computacional, a necessidade das normas Brasileiras de desempenho considerarem a possibilidade de formação de fungos filamentosos nas edificações com baixo e elevado isolamento térmico. Na análise examina-se as condições termo-higrométricas próximas a estrutura de concreto armado do modelo da edificação onde ocorrem as pontes térmicas, e as superfícies dos fechamentos vertical, de alvenaria, para todas as fachadas. Os resultados mostram que existe uma elevada probabilidade de crescimento dos fungos filamentosos nas pontes térmicas quando o edifício é mais isolado, ou seja, apresenta baixa transmitância térmica.

Habitat conditions, spatial distribution and trichome morphology of different species of Tillandsia growing on trees on the Ilha Grande Island, Brazil

Epiphytes living in the canopy face the problem of being exposed to varying levels of air humidity, temperature and insolation, according to both local climate and growing site conditions. This study addresses interrelationships between a) vertical distribution of Tillandsia species on phorophytes of Ilha-Grande Island in tropical Brazil; b) micrometeorological conditions at the different epiphyte habitats and growing sites; c) diurnal changes in plant water content and d) morphological traits of Tillandsia leaves with respect to absorptive scales. For this purpose, five vertical zones of different height and exposure were defined within the canopy, which are characterized by specific epiphyte associations. It was found that the Tillandsia species are heterogeneously distributed within tree canopies. The most exposed sites are colonized almost exclusively by T. usneoides whereas less exposed zones are settled by different assemblages of all other considered Tillandsia species. Microsite conditions (temperature and humidity) were shown to be substantially different, with quite extreme conditions at the sites preferred by T. usneoides. Despite its apparently stressful habitat, T. usneoides showed the lowest decrease of daily water content. All considered Tillandsia species differed significantly with respect to size and density of their absorptive scales. Also, density and size of scales differed within the leaves in a species-specific manner. Tillandsia usneoides was distinctly different from all other considered species by showing the longest scales and a high scale density which was uniform over the leaves. The results demonstrate the unique ability of T. usneoides to cope with drought stress. The outcomes support the assumption that leaf and scale morphology of Tillandsia are correlated with habitat. Probably, a dense mat of filiform leaves covered with scales showing long wing cells – as shown by T. usneoides – is particularly suitable for harvesting atmospheric water.

Predicting Malaria Transmission Dynamics in Dangassa, Mali: A Novel Approach Using Functional Generalized Additive Models.

Mali aims to reach the pre-elimination stage of malaria by the next decade. This study used functional regression models to predict the incidence of malaria as a function of past meteorological patterns to better prevent and to act proactively against impending malaria outbreaks. All data were collected over a five-year period (2012–2017) from 1400 persons who sought treatment at Dangassa’s community health center. Rainfall, temperature, humidity, and wind speed variables were collected. Functional Generalized Spectral Additive Model (FGSAM), Functional Generalized Linear Model (FGLM), and Functional Generalized Kernel Additive Model (FGKAM) were used to predict malaria incidence as a function of the pattern of meteorological indicators over a continuum of the 18 weeks preceding the week of interest. Their respective outcomes were compared in terms of predictive abilities. The results showed that (1) the highest malaria incidence rate occurred in the village 10 to 12 weeks after we observed a pattern of air humidity levels >65%, combined with two or more consecutive rain episodes and a mean wind speed <1.8 m/s; (2) among the three models, the FGLM obtained the best results in terms of prediction; and (3) FGSAM was shown to be a good compromise between FGLM and FGKAM in terms of flexibility and simplicity. The models showed that some meteorological conditions may provide a basis for detection of future outbreaks of malaria. The models developed in this paper are useful for implementing preventive strategies using past meteorological and past malaria incidence.

A study of the incubator model for growing mushrooms

This article describes the automated incubator designs for white mushrooms growing. Mongolia has a very long and cold winter, so the process of growing mushrooms is short. Therefore, we aim to design an automated incubator system that has created a favorable artificial environment for mushroom growing by examining the necessary conditions for mushroom growing. This system was designed to be able to hold for some time the required levels of soil moisture, air humidity, soil temperature, air temperature, and CO2 levels. This article presents the results of a system-based experiment that allows you to grow mushrooms for 30 days without human interference.