Air Temperature Distribution Research Articles

COMPARISON OF INITIAL CLIMATIC INFORMATION FOR CALCULATIONS OF SEASONAL ENERGY CONSUMPTION BY AIR CONDITIONING UNITS

In order to calculate seasonal energy consumption for processing in air conditioning units, the initial climatic information shall contain data on the distribution of outdoor air temperature and humidity over time. The article compares the completeness of the coverage of outdoor air parameters for the Moscow construction area in two climatic models: probabilistic - statistical and climatic curve. The article provides a comparison in the repeatability of the temperature and relative humidity of the outside air for the two mentioned models, as well as for the probabilistic - statistical model built on data from different years. In addition, a comparison of the consumption of heat, water and electricity obtained using the models under consideration for the three summer months is given.

Virus transport and infection evaluation in a passenger elevator with a COVID-19 patient.

Contaminant transport and flow distribution are very important during an elevator ride, as the reduced social distancing may increase the infection rate of airborne diseases such as COVID-19. Studying the airflow and contaminant concentration in an elevator is not straightforward because the flow pattern inside an elevator changes dramatically with passenger movement and frequent door opening. Since very little experimental data were available for elevators, this investigation validated the use of computational fluid dynamics (CFD) based on the RNG k- turbulence model to predict airflow and contaminant transport in a scaled, empty airliner cabin with a moving passenger. The movement of the passenger in the cabin created a dynamic airflow and transient contaminant dispersion that were similar to those in an elevator. The computed results agreed reasonably well with the experimental data for the cabin. The validated CFD program was then used to calculate the distributions of air velocity, air temperature, and particle concentration during an elevator ride with an index patient. The CFD results showed that the airflow pattern in the elevator was very complex due to the downward air supply from the ceiling and upward thermal plumes generated by passengers. This investigation studied different respiratory activities of the index patient, that is, breathing only, breathing, and coughing with and without a mask, and talking. The results indicated that the risk of infection was generally low because of the short duration of the elevator ride. If the index patient talked in the elevator, two passengers in the closest proximity to distance would be infected.

Application of data-driven RANS model in simulating indoor airflow.

The indoor environment has a significant impact on our wellbeing. Accurate prediction of the indoor air distribution can help to create a good indoor environment. Reynolds-averaged Navier-Stokes (RANS) models are commonly used for indoor airflow prediction. However, the Boussinesq hypothesis used in the RANS model fails to account for indoor anisotropic flows. To solve this problem, this study developed a data-driven RANS model by using a nonlinear model from the literature. An artificial neural network (ANN) was used to determine the coefficients of high-order terms. Three typical indoor airflows were selected as the training set to develop the model. Four other cases were used as testing sets to verify the generalizability of the model. The results show that the data-driven model can better predict the distributions of air velocity, temperature, and turbulent kinetic energy for the indoor anisotropic flows than the original RANS model. This is because the nonlinear terms are accurately simulated by the ANN. This investigation concluded that the data-driven model can correctly predict indoor anisotropic flows and has reasonably good generalizability.

Estimating urban spatial temperatures considering anthropogenic heat release factors focusing on the mobility characteristics

As climate change intensifies, it is an important task in reducing heat disasters to derive which areas are most vulnerable by exploring factors that affect thermal environment. Anthropogenic heat release factors have contributed to local temperature increases in cities. However, existing studies have mainly focused on the static sector of anthropogenic heat release factors. Therefore, this study addresses the effects of urban spatial temperatures considering anthropogenic heat release factors, with a focus on the mobility sector. An average summer temperature (avS) estimating model was developed with deep neural network (DNN) and random forest (RF) in detailed spatial units within a city (1 km spatial resolution) using eight mobility sector and four static sector indicators as input variables. The feasibility of introducing mobility indicators was verified by performing a correlation analysis between temperature and traffic flows. Mobility exhibited a higher correlation with the climate sector than with static road indicators. The RF model with mobility indicators effectively estimated spatial distribution of air temperatures, with an RMSE of 0.0777 and R2 of 0.9121, and outperformed the DNN model. This study provides a reference for heatwave risk management and the control of various urban anthropogenic heat release factors, including the mobility sector.

Condensation Zone Estimation and Determination and Comparison of Condensation by Numerical Analysis in Vehicle Lighting System

The condensation problem in automobile lighting system risks driving and driver safety. Condensation is the main cause of problems such insufficient lighting. In our study, the problem of condensation in vehicle headlights is discussed. The region where condensation will occur was estimated from the results obtained from the temperature analysis. The amount of condensed mass was calculated by the calculation method. Calculations were confirmed by numerical analysis. In the analyzes made in ANSYS 2022 R2 software, the transmission effects (conjugate effects) in the headlight components were taken into account. Boussinesq approach was used for natural convection and Monte Carlo approach was used for considering radiation effects. Mesh independence was was studied. Thermal analyzes were made at ambient temperature T∞=5 °C and RH: 95% independent of time. As a result of the analysis, the indoor air temperature distribution, air flow profiles were examined and an estimate was made where the condensation would occur. Then, the thermal analysis results were read as the initial condition, and it was kept for 300 seconds. Water at 3 °C was sprayed onto the lens. Condensation formation analyzes were made in terms of time. After the formation of condensation, the power was turned on to the lighting elements and it was expected that the condensation would be removed within 1800 seconds as per the specification. The region where condensation is predicted and the region with condensation in the analyzes are compatible with the literature.

Full-scale three-dimensional simulation of air-cooled proton exchange membrane fuel cell stack: Temperature spatial variation and comprehensive validation

This study presents one of the first full-scale stack three-dimensional (3D) simulations for proton exchange membrane (PEM) fuel cell to investigate temperature distribution, cell/stack performance, and impact of air cooling. The stack consists of 30 cells with the active area of 50 mm × 200 mm for each fuel cell. The manifold and all the basic components are included in the computational domain, while the flow field structure is treated as porous media in order to reduce the computational burden. The model predictions are validated against the experimentally measured voltage and detailed temperature distribution under different currents. It is found that significant differences in temperature are present between the fuel cells at the two sides and that in the middle, and the oxygen content becomes lower at a higher temperature site due to the local increased water vapor concentration. As a consequence, thermal behavior has a decisive effect on the distributions of temperature, reactant concentration, membrane hydration, current density, etc., inside this air-cooled stack. It is also found that increasing the cooling air flow rate not only decreases the stack temperature, but also reduces the temperature variation, which further benefit the uniform distributions of oxygen, water vapor, etc. in the stack.

Research on the thermal comfort of passenger compartment based on the PMV/PPD

With the increasing requirements of consumers for vehicle performance, the thermal comfort has become a key index of consumers. The thermal environment inside the passenger compartment directly determines the thermal comfort of vehicle. In this paper, the vehicle cabin and the heat fluxes are measured at different thermal environment. The thermal comfort of the passenger compartment is analyzed based on Computational Fluid Dynamics. The transient response of the thermal environment of passenger compartment is investigated, and the thermal comfort of the passenger compartment is evaluated based on the PMV/PPD (Predicted Mean Vote/Predicted Percentage Dissatisfied) evaluation index. By analyzing the air temperature and velocity distributions from the transient model, the effect of the field synergy angle is used to explain the different thermal distribution based on different heat dissipation conditions. The results showed that the smaller the field synergy angle, the stronger the heat transfer performance.

Influence of tunnel ventilation on the indoor thermal environment of a poultry building in winter

Tunnel ventilation systems are widely used to create thermal environments for poultry buildings in China. However, existing research mainly focuses on the indoor thermal environment in summer and rarely considers the winter season. A field test was conducted in a layer breeder building in Handan City, China to systematically investigate the characteristics and problems of the thermal environment in winter. Forty-two measuring points were set to analyze the indoor air velocity and temperature distributions, and the nonuniformity coefficient and temperature humidity velocity index (THVI) were adopted as the evaluation indices. Furthermore, the exhaust fan layout of tunnel ventilation was explored to improve the indoor thermal environment using a validated computational fluid dynamics (CFD) method. The results show that (1) the indoor air velocity distribution is quite nonuniform with a nonuniformity coefficient of 0.74, the maximum difference of which is as large as 0.62 m/s; (2) the nonuniformity coefficient of indoor air temperature distribution is 0.16, and the maximum temperature difference is as large as 12.9°C; (3) the indoor THVI is below the appropriate range of 18–25, making the thermal comfort zone only 61.4%; (4) separately installing exhaust fans at the front and end walls with the symmetrical locations and sizes can improve the distribution uniformities of indoor air velocity and temperature by 22.0% and 88.3%, respectively. The experimental results and parametric optimization of tunnel ventilation in this study will be beneficial for designing an appropriate thermal environment for poultry buildings during winter. • The non-uniformity coefficient of air velocity in experimental poultry house is 0.74. • The maximum difference of air temperature in experimental poultry house is 12.9 °C. • The thermal comfort zone in experimental poultry house is only 61.4% of entire space. • Separately installing exhaust fans on front and end walls improves the environment.

Estimating spatial distributions of design air temperatures for ships and offshore structures in the Arctic Ocean

To provide some design references for ships and offshore structures to operate in the Arctic waters, we assessed the spatial distributions of design air temperatures (DATs) in the Arctic Ocean using a 40-year MERRA-2 air temperature reanalysis data (1981–2020). The DATs studied included the design temperature (tD), polar service temperature (PST), lowest anticipated service temperature (LAST), and record lowest temperature (RLT). Higher DATs were observed in the Atlantic Arctic sector than Pacific Arctic sector. The lowest DATs were mainly in the Central Arctic Ocean near Canada. Moreover, the PST was generally lower than the RLT in the summer months. The lowest yearly (summer) tD for the Northeast Passage, the Transpolar Sea Route, and the Northwest Passage were −34.2 °C (−8.7 °C), −33.4 °C (−16.2 °C), and −32.0 °C (−13.2 °C). They are used to determine the steel grade requirements for ships. Not all regions in the Arctic Ocean had a rising trend in the yearly extreme low temperature under Arctic warming, especially in some nearshore areas. Furthermore, a strategy was provided for LAST uncertainties caused by climate change. These results and treatments provided references for future polar engineering designs.

Land use and cover change in Northeast China and its impacts on the Xing'an permafrost in 1980s–2010s

AbstractBoreal forest and wetland have important influences on the development and protection of the ecosystem‐dominated Xing'an permafrost. However, the responses of different ecosystems to climate change and the impacts on the underlying permafrost are still unclear. Here, based on the multi‐period land use/land cover (LULC) data and long‐time series of air temperature, combined with the ordinary least squares (OLS) and ordinary kriging (OK) methods, the effects of land use and cover change (LUCC) on the distribution of mean annual air temperature (MAAT) and permafrost in Northeast China were analyzed. From 1980s to 2010s, MAAT showed an upward trend (0.025°C per yr) and extents of permafrost showed a decreasing trend (−3668 km2yr−1) in Northeast China. Permafrost degradation mainly occurred in forested land and grassland, with areal reductions of 4.0106 × 104and 3.8754 × 104 km2, respectively. The transformation of LULC aggravates the degradation of permafrost. The conversions of forested land and grassland to cultivated land and forested land to grassland resulted in the shrinkage of permafrost extent by 6233 km2from 1980s to 2010s . Our results confirm the significant impacts of LUCC on the Xing'an permafrost resulting in its degradation. Additionally, they can provide a scientific basis for ecological environment protection and restoration and sustainable development of boreal forest and wetland ecosystems in permafrost regions of Northeast China.

Distribution of air temperature in the territory of Ukraine against the background of current climate changes

Monitoring climatic studies of the territory helps us to establish the peculiarities of the temperature regime, to find out the indicators of the frequency and intensity of extreme weather phenomena, inherent in modern climatic conditions. The study of their trends and the variability of spatial-temporal features remain a priority area of hydrometeorological scientific and practical research. The aim of the article is to study the patterns of air temperature distribution in the territory of Ukraine for two thirty-year periods (1991-2020, 1961-1990). Main material. World and domestic research results of modern climatic conditions indicate significant warming processes observed in all seasons. Significant climatic changes for the studied territory are gaining faster pace, causing a number of problems in the socio-economic sphere, which have an impact on the country’s food security. Established trends of climatic time series of average monthly air temperature throughout the year and seasons at twenty-five meteorological stations recorded transformations of regional temperature conditions at the end of the 20th - beginning of the 21st centuries (1991-2020). Such trends in the variability of the temperature regime of the territory directly lead to further additional studies of the local and regional climate, forecasting strategies for prevention and adaptation to probable changes. The analysis of average monthly air temperature indicators during the year for the periods 1961-1990 and 1991-2020 records a warming that covers all the presented weather stations. Conclusions. The results of the study establish a steady trend towards warming of the regional climate during the period 1991-2020, drawing attention to measures of adaptability to it, further study and forecasting of climatic indicators. A feature is the rate of warming, characterized by significant growth rates, reflected in the restructuring of the regional climate and the global climate system.

ПРИМЕНЕНИЕ МЕТОДОВ МАТЕМАТИЧЕСКОЙ СТАТИСТИКИ ДЛЯ ОЦЕНКИ УРОВНЯ ЛАВИННОЙ ОПАСНОСТИ В ГОРАХ ИЛЕ АЛАТАУ

The Institute of Geography and Water Safety adapted the world experience in assessing the avalanche danger level to the conditions of Kazakhstan. This work is based on the five-point scale method of danger level classification recommended by the WSL Institute for Snow and Avalanche Research (SLF). The methods of mathematical statistics are used to analyze data on weather conditions and avalanches. The analysis identified the main statistical parameters of data series. The cluster analysis revealed five similar groups (clusters) in the distribution of snow water equivalent and air temperature and three clusters in the distribution of precipitation amounts. The spectral analysis showed that the duration of avalanche periods is basically 2-3 days. The distribution of the number of days with different levels of avalanche danger, total volumes of avalanches and heavy precipitation obeys the Pareto law. The results are statistically significant according to the Kolmogorov-Smirnov test (α = 10%, p < 0.01).

An aisle displacement ventilation system for twin-aisle commercial airliner cabin

The environmental control system in most commercial airliner cabins supplies air from shoulder and ceiling level and exhausts air at floor level on both sides of walls. The ventilation system mixes air in the cabins to create a uniform air temperature distribution that is great for thermal comfort. However, the mixing ventilation also enhances airborne contaminant transfer. Displacement ventilation has been proposed for use in cabins, but they may create high air temperature stratification and draft. This investigation developed an aisle displacement ventilation (ADV) system that can reduce air temperature stratification and be easily installed in cabins. By installing the system in a five-row, twin-aisle cabin mockup, our study found that ADV can create a low air velocity distribution in the cabin and can maintain an acceptable air temperature stratification without draft. The system created an uprising flow that can effectively remove airborne contaminant generated from respiratory activities. The experimental data were used to validate a computational-fluid-dynamics (CFD) program. The validated CFD program was used to compare the ADV with the under-seat displacement ventilation (USDV) and the underfloor air distribution (UFAD) along the aisles. The ADV had better thermal comfort than the other two systems, but the cabin air quality of the three ventilation systems was similar.

A global thermal node model for no-load indirect solar dryer

ABSTRACT This paper presents a global thermal node model for predicting heat transfer in no-load indirect solar dryer. The overall influence of the interaction of the indirect solar dryer with the uppermost soil layer is considered. The mathematical model describing the solar drying system with a double-pass air-circulation collector is derived. Based on the Moore and Fisch approach, the soil surface fluxes are calculated using the surface layer similarity theory. The drying air temperature distribution based on dynamic descriptions of the drying environment is studied. The unsteady convection heat transfer results low thermal efficiency of the dryer at low air speed. The linear increase of the inner air speed from to makes the maximum efficiency increases of . When the offsetting air speed undergoes a convex quadratic increase, the average value of the energy efficiency in this case increases of compared to the scenario of constant air speed.

Вплив різних технологій вирощування на чисельність основних еколого-трофічних груп мікроміцетів ґрунту

During 2021 on the basis of stationary field experiments, which are located in of the Skvyra Research Station of Organic Production (Kyiv region), the Nosivka selection research station (Chernihiv region), the Institute of Vegetable and Melon NAAS (Kharkiv regions) and in a private farm of organic production FOP Shanoilo (Chernihiv region) were studied of the quantitative composition of soil micromycetes under different agricultural crops: winter wheat, oats, rye, barley and onions. The research was conducted on different cultivation technologies: traditional, organic and mixed. Weather conditions during the research vegetation period differed for agrometeorological indicators. The characteristic feature was a contrast of differences in air temperature and unequal distribution of rainfall, which affected the composition of the soil mycobiocenosis. The vegetation period of 2021 in Kyiv region was characterized by sufficiently moist (HTC 1,7), and in Chernihiv and Kharkiv regions drought prevailed (HTC 0,6). Adverse weather conditions such as drought and waterlogging of the soil contributed to changes in the number of mycobiomes of the studied soils. Mycobiota are integral homeostatic components that affect what determines its important functions and the possibility of a continuous cycle substances. It is shown that cultivation technologies depending on the system of fertilizer and crop protection affect the formation of soil mycobiome. The of stationary field experiments that characterized by typical chernozem are more stable and balanced structure of soil microbiocenosis than low-fertile sod-podzolic soils, where the number of major ecological and trophic groups of micromycetes under different crops was twice as lower. It was found that each plant variety has a specific mycobiome of the rhizosphere, depending on the available soil group. It is determined that the number of major ecological and trophic groups inhabiting the rhizosphere of different crops depends from phase development of plant, soil and climatic conditions, soil type, fertilizer system and the cultivation technology and type of crops.

Numerical Simulation of High-Speed Rotor for Air-cooled Eddy Current Dynamometer

The key feature of air-cooled dynamometer is the geometry of the rotor, which played a vital role in effective heat rejection. Dual application is limited for air cooled eddy current dynamometer due to excessive heat generation when the operating speed is up to a certain range. The aim of this research is to observe the air flow pattern and temperature distribution on the rotor of the air-cooled dynamometer with different geometry designs. In addition, the air flow and heat transfer simulation were carried out by using ANSYS software. Besides, the setting of normal size mesh was proposed in all design cases to reduce the computational time and the mesh files size of the simulation. Furthermore, a total of four configurations of rotating domain were designed and created using SolidWorks software, with each one differentiated with the features of holes and cover. The results of air flow velocity contour were compared with those of without the cover and holes on the rotor design. The optimum design in air motion distributed within all cases of numerical simulation were then observed and compared. To validate the simulation setup, experimental data were used to validate the airflow and heat transfer coupling simulation models. The results revealed that an improvement with more air volume movement can be observed at medium range and high velocity range for all models with cover features over the models without cover. Besides, the results also shows that the influences of hole features on air flow velocity were less significant as compared to the one with cover features. Also, the rotor design with cover and without holes were found to be the best configuration as it allows the as high as 27.7% greater air flow dynamic to achieved lowest steady state temperature as compared with those of baseline design. The Design C also improved in term of temperature as compared to the simple model of plane rotor, with as high as 11.6% reduction in overall temperature. Through the results of this analysis, it was justifiable that the Design C can be suggested as the best-case scenario for further experimental study. These results will serve as a basis for rotor design to improve the performance of the air-cooled eddy current dynamometer.

Multi-objective integrated BES-CFD co-simulation approach towards pandemic proof buildings

COVID-19 has posed an extraordinary burden to those professionals responsible for properly operating and safely maintaining facilities throughout this disaster. Considering this global pandemic, the common spaces in buildings must be reconsidered to accommodate a future in-presence existence. Governments address human health and safety as the most vital considerations worldwide; thus, Heating, Ventilation, and Air Conditioning (HVAC) designs, airflow patterns, and temperature distribution must all be reconsidered to achieve such healthy circumstances. Based on this, a Building Energy Simulation-Computational Fluid Dynamics (BES-CFD) validated model has been analysed in terms of various HVAC designs. The simulations assessed the proposed solutions in terms of energy-saving, operational CO2 emissions, thermal comfort enhancement, and infection control. The results were closely examined and showed that the Underfloor Air Distribution (UFAD) system generates approximately laminar vertical airflow, reducing the likelihood of indoor infections and viral transmission. Supply air is delivered to the inhabitants’ zone without sacrificing mixing efficiency, ensuring long-term indoor environmental quality. Moreover, the UFAD model proved to be more cost-efficient compared to the Conventional Overhead Distribution (COHD) and has a lower carbon footprint and energy consumption. In terms of thermal comfort, the dynamic simulations showed a noticeable enhancement in PMV. Additionally, the UFAD provides a vertical temperature gradient profile that is sufficiently uniform. Moreover, the integrated DOAS-UFAD systems’ effectiveness was proved through a techno-economic analysis with a Return on Investment of 8.25% and a Payback period of 7.3 years.

Regression Analysis Performed with Respect to the Velocity and Temperature

Abstract: Today vehicles are like our necessity in life. Most of the people of metro cities spend minimum 2-4 hour daily in their car. So people want better thermal comfort. Nowadays companies start focusing on customer choice. Vehicular cabin climate is adjusted by making changes in dry bulb temperature. It depends upon person that in which range person feels thermally comfort. This temperature range is always deviate from person to person. Every person has different metabolic rate so range of thermal comfort diverges person to person and it also depend upon clothing of people. If more powerful air-conditioner is applied then it affects the car performance means it lessen the average of vehicle. Air-conditioner will be applied in a limit. Thermal comfort is depending upon capacity of air conditioner, air velocity in car cabin, Air temperature, humidity and air flow distribution. So, first thing is capacity of air conditioner that will not be altered to higher value because AC is one and the only thing which consumes more power than other equipment. If large air conditioner is applied it will not be economical also. This is not the optimal solution for increasing thermal comfort. Air temperature can be decreased to improve thermal comfort but in this case size or capacity of air-conditioner will increase, ultimately this will increase cost. Last parameter is air flow distribution in which the pattern of air flow will be analyzed. In hatchback cars always there is a complaint of uneven cooling means cooling at front seat is good but very less cooling at back seat. Generally after an hour you feel some cooling at back. So there is need of optimal solution which is not too costly and also economic with respect to kilometer per liter. In this study of air pattern conclusion can be drawn that if there is any A.C. 2 vent will also present for back seat. Thermal comfort is also relying on Glass transmissivity of window glass in car cabin.

Ecological strategy of using agricultural land in Ukraine

The article is devoted to the problem aspects of agricultural land use in Ukraine. Analysed influence on using of agricultural land such factors as systems of farming, global warming, uneven precipitation distribution by months and deficit of humus in the soil. Considered such system of farming as traditional, organic, No-Till and made conclusion about a harmfulness of traditional farming system on ecology. Analysed the influence of organic and No-Till farming systems on preservation of moisture in the soil under condition of increasing of air temperature and uneven distribution of precipitation by months. Made conclusion that in contrast to traditional farming system, organic farming system is able to improve a state of ecosystem, in particular a biological variability, biological cycles and biological soil activity. It is a possible by using cultural, biological and mechanic methods when cultivating the land in opposite to synthetic materials. So, organic farming is not only a system of agricultural production, but also is a complex approach for supporting of sustainable development of agriculture. The advantage of organic farming is a possibility for adaptation to many climate zones and local conditions.

Effects of humidification process on thermal performance of floor heating systems: An experimental study

In dry and cold climates, a cool mist humidifier and a floor heating system are typically used in combination to achieve a pleasant residential environment. In order to investigate the interaction between a humidification process and a heating process, a total of 12 experimental tests were carried out, which included nine experimental groups with a humidification process under the conditions of three indoor temperature set points (21 °C, 23 °C, 25 °C) and three relative humidity set points (45%, 55%, 65%), and three control groups with no humidification process under the conditions of three indoor temperature set points (21 °C, 23 °C, 25 °C). Obtained results show that the indoor environment will reach a new balance in the process of competition between the evaporative cooling and the floor heating, and the floor surface temperature increases when the humidification level rises. The floor overheating problem should be considered while meeting humidification needs at air temperatures of 25 °C or above. The humidification process makes the air temperature distribution more uniform, but increases the energy consumption noticeably. In addition, exergy loss is mainly concentrated in two areas: the building envelope and the floor for the floor heating system. In summary, the set point of RH 45% could meet general health requirements in the case of minimal energy consumption. RH 55% could be selected at below 25 °C for better thermal comfort in particular situations where the energy consumption is acceptable.