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One of the significant ways to reduce the destructive impact on the environment from the technological processes of restorative repair of car bodies is the transition to paints diluted with water. However, the direct use of existing paint drying chambers for the application and drying of waterborne paints can negatively affect the performance of the process and the quality of the coating. It has been established that during the drying of coatings from waterborne paints, the formation of stagnant ventilation zones is possible, which can lead to reverse condensation of water, followed by the formation of streaks. The purpose of the study: to increase the efficiency of the process of painting automobile bodies with paints diluted with water, based on the control of the parameters of the air environment of the paint drying chambers. Research methods: analysis of ventilation processes in existing paint-drying chambers and their compliance with the thermophysical and volatile properties of water vapor when painting automotive products. In order to avoid the formation of stagnant zones of high humidity in the ceiling part of the paint and drying chambers, it is proposed to mount a system of guide plates, the purpose of which is to control the directions and speed of air flows in the painting and drying modes. To ensure acceptable technological and economic parameters of the process of painting with waterborne paints, depending on the humidity levels in the environment and in the working chamber of the paint and drying chambers, it is proposed to change the logic of the recirculation flap control. Dependencies linking the parameters of the movement of the executive bodies with the indicators of humidity, mode and direction of the flow of ventilated air are proposed. The scientific novelty of the work lies in the methodology for controlling the humidity level, direction and mode of air flows in the working chamber of the paint and drying chambers, which eliminates the appearance of stagnant zones when painting car bodies with waterborne paints. The direction of further research is to substantiate the optimal level of air humidity in the working chamber, depending on the state of the ambient air and the productivity of the painting process.

Dust pollution for ventilation systems is a big problem for mine workers in underground coal mines. The respirable dust concentration is important to the physical and spiritual health of miners. It is hazardous up to 2 mg/m3in the air in underground coal galleries. In the present work, the airflow velocity and dust concentration values were measured at Çay 1-Kartiye roadway in Kozlu, Zonguldak. The goal of this research is modelling to the dust concentration and airflow velocity values by the computational fluid dynamics (CFD) method. An airflow and dust fluid and solid model was done using the Eularian-Granular multiphase method with the k-epsilon two-equation model. The results showed that dust concentration values were too low and fixed. The error percentage of airflow velocity values changed between 5% and 17%. Thus, this roadway is safe for coal dust explorations.

Heat stress has posed a significant threat to the laying hens inside the poultry houses in the Northwest region of China. Significant non-uniformities can be found in the thermal distribution and temperature variations in summer. The ventilation system has been the primary measure to regulate the thermal environment in the poultry houses. Excellent airflow arrangement and ventilation strategies are essential for the ventilation efficiency. Still, the continuous operation of fans can inevitably generate the excessive local cold air, thereby wasting the electrical energy for the high cost of environmental control. Alternatively, intermittent ventilation can serve as an efficient way to improve ventilation effectiveness with energy saving. However, it is notably limited to applying to the summer poultry houses so far. In this study, a novel intermittent ventilation was introduced to alleviate the significant temperature fluctuations and ensure the high stability of the thermal environment in the summer poultry houses. According to the internal air temperature, the fan operations were performed on the conventional tunnel-ventilated poultry houses (control house, CH) and sidewall inlets poultry houses (experimental house, EH). Specifically, the fans were regulated, when the temperature exceeded the upper limit. Once the temperature dropped below the lower limit temperature, the fans were deactivated simultaneously, which was different from the continuous operations of fans throughout the summer. The thermal environment was monitored in the operation periods of intermittent ventilation. The environmental conditions inside the poultry houses were also evaluated. The results revealed that the average internal temperatures of experimental and control poultry houses were 25.3 and 26.5 °C, respectively, under the same external environmental temperatures; While the average relative humidity were 65.8% and 62.7%, respectively. The temperature fluctuations during the EH and CH's intermittent and continuous ventilation were 0.6 and 0.7 °C, 1.2 and 1.0 °C, respectively. The maximal difference of temperature in the horizontal direction of EH and CH were 0.3 and 5.2, 0.8 and 4.7 °C, respectively. Temperature variations were assessed in the four-hour intervals. The EH consistently demonstrated more minor temperature fluctuations than the CH when the fans were operated intermittently. The horizontal temperature difference was less than that in the continuous operation in EH. There was no difference in pressure and air velocity under the intermittent and continuous ventilation in the same number of fans. The pressure difference between the interior and the evaporative cooling pad buffer room increased from 17 to 19 Pa from the fan opposite wall to the fan. Average air velocity at the sidewall inlets and along the aisles in the EH were 3.30 and 0.49 m/s, respectively, which were higher by 1.86 and 0.12 m/s, compared with the CH. Therefore, the intermittent ventilation was suitable for the sidewall inlets, to improve the thermal environment within the poultry house significantly. There was great potential for widespread adoption in the Northwest region of China in the summer. The lifespan of the fan was extended for the maximal economic benefits. The intermittent operation times of fans should be determined according to the local climate, poultry houses’ ventilation requirements and the poultry houses’ size. This finding can provide a foundational reference for designing and adjusting the intermittent ventilation in summer poultry houses in the Northwest region of China. [ABSTRACT FROM AUTHOR]

On a mounted laboratory stand, comparative tests were carried out on the effectiveness of spraying wheat plants with liquid using a multi-rotor drone. The study was undertaken with and without propeller rotations. The lack of rotations simulated spraying by a ground sprayer. The height of the drone's displacement above the plants was similar to that of the nozzles above the plants used when spraying with field sprayers, 0.5 m and 1.0 m. The speed of the drone movement was 0.57 and 1.0 m·s−1. The effects of the height and speed of the drone's movement and the impact of the airflow on the volume and uniformity of the liquid application on the plants were assessed. In addition, changes in the transverse distribution of liquid volume in the droplet stream and the transverse distribution of the air velocity in its stream were evaluated. The liquid was sprayed at a constant pressure of 0.2 MPa. The study's results show that the low height of the drone displacement not only had a strong effect on increasing the liquid volume applied to the plants but also improved the uniformity of application at plant levels. It was also noticed that, at a height of 0.5 m, there was a significant irregularity in the air stream under the drone. [ABSTRACT FROM AUTHOR]

Simple Summary: The use of single-box housing for domestic horses is a matter of concern due to its potential negative effects on their social interaction and movement. Horses in tropical regions may also face challenges due to heat and humidity fluctuations affecting their thermal comfort and heat dissipation. This study sought to explore the stress responses in horses housed in different stable designs in a tropical savanna region, as little research has considered this topic. The results reveal correlations across stable designs between internal humidity, air temperature, ammonia levels, and heart rate variability (HRV) modulation in horses. We also observed distinct stress responses in horses in different stable designs. These findings suggest that daily changes in the internal environment, as well as stable design, play crucial roles in affecting horses' stress responses and overall well-being in tropical savanna regions. These results have important welfare implications for the management of horse housing in such environments. Single-confinement housing can pose welfare risks to domestic horses. This study investigated horses' stress responses when confined to single stalls in different stable designs in a tropical savanna region to address a gap in the literature. In total, 23 horses were assigned to a stable with a central corridor and solid external walls (A) (N = 8), a stable with one side corridor and solid external walls (B) (N = 6), or a stable with a central corridor and no solid external walls (C) (N = 9). Air velocity, relative humidity, air temperature, and noxious gases were measured inside the stables, and the heart rate and HRV of the horses were also determined. The relative humidity was lower in stable C than in stable A (p < 0.05), while the air temperature was higher in stable C than in stable B (p < 0.05) during the day. The airflow and ammonia levels were higher in stable C than in stables B and A (p < 0.01–0.0001). Overall, horses' HRV in stable A was lower than in those in stables B and C (p < 0.05–0.01). Horses in stable A tended to experience more stress than those in other stables. [ABSTRACT FROM AUTHOR]

At present, air handling units are usually used indoors to improve the indoor environment quality. However, while introducing fresh air to improve air quality, air velocity has a certain impact on the occupants' thermal comfort. Therefore, it is necessary to explore the optimization of air-fluid-body interaction dynamics. In this study, the indoor air flow was changed by changing the opening and closing degree of the blower, and the thermal manikin is introduced to objectively evaluate the human thermal comfort under different air velocities. The main experimental results show that the air change rate increases with the increase of the opening and closing degree of the blower considering an ACH (air changes per hour) range between 3.8 and 10. For a better prediction, a linear correlation with a coefficient of 0.995 is proposed. As the blower's opening is adjusted to 20%, 25%, 30%, 35%, and 40%, the air velocity sensor positioned directly beneath the air inlet records average velocities of 0.19, 0.20, 0.21, 0.28, and 0.34 m/s over four hours, respectively. Observations on thermal comfort and the average sensation experienced by individuals indicate an initial increase followed by a decline when the blower's operation begins, with optimal conditions achieved at a 35% opening. These findings offer valuable insights for future indoor air ventilation and heat transfer design strategies. [ABSTRACT FROM AUTHOR]

Airflow plays a crucial role in plant growth because it supplies CO2, O2, and energy to plants in a plant factory with artificial light (PFAL). Therefore, understanding how various factors affect airflow in and around a plant canopy is essential. In this study, we developed a computational fluid dynamics (CFD) model with realistic plant structures created using structure-from-motion imaging to investigate airflow in and around a plant canopy. The averages of the absolute percentage errors of simulated air velocity in three conditions were 6.7%, 10.1%, 12.7%, respectively. The simulated and measured air velocities agreed well, confirming the accuracy of the developed CFD model. The effects of inflow velocities and plant canopy structures on the airflow in and around the plant canopy were analysed using the validated CFD model. The inflow velocities significantly decreased stagnant zones (from 62.4% to 7.2%) and increased the airflow uniformity in and around the plant canopy. A staggered layout of the plant canopy slightly decreased stagnant zones (from 16.4% to 13.2%) and increased the airflow uniformity. The airflow in and around the plant canopy was further inhibited by a large plant structure. This CFD model provided a basis for improving the airflow status in and around a plant canopy in a PFAL. [ABSTRACT FROM AUTHOR]

This article presents a study on the capture velocity of local exhaust ventilation (LEV) using a specially designed workstation within a laboratory setting. The workstation featured a worktop with dimensions of 90 cm width and 45 cm depth, and the exhaust duct was positioned near the pollutant source, considering the intended operation of the LEV system. The worktop was divided into squares for precise documentation and remeasurement. A supply duct above the worktop provided controlled fresh airflow. Smoke was used to visualize airflow patterns. The measurements focused on air velocity and turbulence intensity, aiming to understand flow structures and vortices. Various capture rates were tested at specific measurement points. The study revealed that the central capture lines yielded the highest efficiency. To address air extraction from behind the exhaust duct, a back sheet panel was introduced. The results showed that installing a back sheet enhanced capture velocities. The findings contribute to understanding LEV efficiency and the importance of proper design and adjustments for effective containment of contaminants in the occupational environment. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Engineering & Architectural Faculty of Eskisehir Osmangazi University / Eskişehir Osmangazi Üniversitesi Mühendislik ve Mimarlık Fakültesi Dergisi is the property of Eskisehir Osmangazi University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Engineering for Thermal Energy & Power / Reneng Dongli Gongcheng is the property of Journal of Engineering for Thermal Energy & Power and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The indoor climate to which livestock are exposed is a critical factor influencing their performance and productivity. Elevated air temperature and relative humidity could result in heat stress for laying hens. This situation results in severe adverse effects such as weight loss and mortality. Egg fertility and hatchability are also impacted. Consequently, a study was carried out in a naturally ventilated battery-caged laying hen house to measure climatic variables (air temperature, relative humidity and air velocity). The degree of heat stress was assessed using the temperature-humidity index (THI), and the index of temperature and air velocity (ITV) was also evaluated. According to the results obtained, birds reared within the study building would spend most of their productive life under stressful thermal conditions, which could significantly hamper their performance. The air velocity was below 1.0 ms−1 for most of the internal part of the housing, meaning natural air movement at the location was insufficient to provide a suitable environment for the birds. A high THI was recorded for nearly the entire study period. This high THI could indicate high relative humidity about air temperature. The observed ITV values (ITV > 25) suggest that birds throughout the building could be perpetually uncomfortable. The thermal and velocity profile within the structure could further be assessed numerically using computational fluid dynamics. This would enable engineers to make modifications to improve living conditions within the building. [ABSTRACT FROM AUTHOR]

The risk of lactating cows experiencing heat stress is increasing because of increased productivity. A steadystate process-based model described by Nelson and Janni (2023) and assessed by Janni et al. (2023) was used to compare additional combinations of environmental conditions (e.g., air dry-bulb and dew-point temperatures, air velocity, solar load) and lactating cow characteristics (e.g., body mass and daily milk yield) on modeled respiration rate. Respiration rate was linked to qualitative heat stress levels, based on work by Renaudeau et al. (2012). The model demonstrates how cows with greater body mass have larger inspired volumes of respired air (i.e., liters per minute) because they have larger tidal volumes (i.e., liters per breath) while they have lower respiration rates (i.e., breaths per minute) compared to cows with smaller body masses. The modeled results support previous studies that demonstrated heat stress increases with greater daily milk yields, solar load, and air dry-bulb and dew-point temperatures. The model finds conditions where increasing air velocity at cow level can help cows reduce heat stress levels due to solar load, and high air dry-bulb and dew-point temperatures. A comparison to a field study demonstrates the need to align field data collection and model input needs to explore the actual or potential impacts of mitigation methods like shade, evaporative cooling, and air velocity (i.e., via fans). This report demonstrates how the model can be used by engineers to investigate the impact of ventilation system designs on respiration rates using current and future technologies. [ABSTRACT FROM AUTHOR]

SUMMARY: Nutritional test pens are commonly used to segregate and geolocate birds in commercial-scale broiler houses to control spatial variation from the environment. Pens should subject test birds to similar environmental conditions as birds roaming free in the house, however, discussions on pen construction materials, design, and placement have focused on durability and handling with little regard for the pen's thermal environment. Simulated birds were constructed with a metal bowl and a light bulb heat source to mimic the heat generation of large commercial broilers. Bowl surface temperature (BST) was measured as a model for the surface temperature of a broiler housed in a nutritional pen. Effects of panel open area (100% (control), 89%, 85%, 70%, 50%, and 30%) and air velocity (2, 3, and 4 m/s) were factorially tested on BST in a wind tunnel. Panels with an open area of less than 70% were different (P < 0.0001) from free air (100% open area). There was a difference of 5°C (9°F) for BST between the most restrictive panel (30%) and free air (100%), demonstrating a large difference in the thermal environment that birds might experience if air is restricted. Air velocity treatments were different (P < 0.0001) with mean BST increasing as air velocity decreased. Panels should be constructed with open areas greater than 70% accounting for structural framing and other obstructions as well as expected dust accumulation. While pen durability and handling are important for on-site success, these parameters should not overshadow restrictive airflow pen designs that would potentially alter thermal environmental conditions in nutritional treatment comparisons.Mention of trade names or commercial products in this article is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the authors or the U.S. Department of Agriculture.

Drying of timber is an inevitable process in quality production. Today, there are drying kilns that their environmental conditions can be controlled. However, this control flexibility also brings with it attention to every variable in the environmental conditions. In this study, it was tried to determine the air movement speed of these variables, its effect on drying and the effect of the gap closing board (panel) placed to direct the air movement to improve drying conditions. In this context, approximately 10 m3 of oak lumber was dried in a dehumidifier (condensation) drying kiln with a semi-automatic control system. After drying, the moisture content of the lumbers were determined and the air movement speeds between the stack floors were measured with an anemometer from a total of 42 regions with all fans on, using two plenum chambers as a reference. The results obtained indicate that low quality or non-standard drying was carried out according to the moisture distribution criteria in the standards, as the ideal drying conditions were not achieved without installing the panel. It was determined that the air movement profile improved with the intervention made with the panel and the air was distributed more homogeneously between the stack floors. Despite the installation of panel, sufficient improvement in air movement speed could not be achieved only on the upper floors of the stack, due to a problem also mentioned in the literature. However, since only electricity is used for heating and air movement in the kiln, the electrical energy consumed during drying was also measured and correlated with the outdoor temperature in order to raise awareness. The results showed that consumption data did not change according to changes in weather conditions. It was thought that the kiln insulation performance and/or the kiln being located in a closed area were effective in this situation. It was concluded that the increased average energy consumption in the second half of drying might be according to the condensation device being activated more related to the more severe conditions required in the drying program.

On a mounted laboratory stand, comparative tests were carried out on the effectiveness of spraying wheat plants with liquid using a multi-rotor drone. The study was undertaken with and without propeller rotations. The lack of rotations simulated spraying by a ground sprayer. The height of the drone’s displacement above the plants was similar to that of the nozzles above the plants used when spraying with field sprayers, 0.5 m and 1.0 m. The speed of the drone movement was 0.57 and 1.0 m·s−1. The effects of the height and speed of the drone’s movement and the impact of the airflow on the volume and uniformity of the liquid application on the plants were assessed. In addition, changes in the transverse distribution of liquid volume in the droplet stream and the transverse distribution of the air velocity in its stream were evaluated. The liquid was sprayed at a constant pressure of 0.2 MPa. The study’s results show that the low height of the drone displacement not only had a strong effect on increasing the liquid volume applied to the plants but also improved the uniformity of application at plant levels. It was also noticed that, at a height of 0.5 m, there was a significant irregularity in the air stream under the drone.

Single-confinement housing can pose welfare risks to domestic horses. This study investigated horses’ stress responses when confined to single stalls in different stable designs in a tropical savanna region to address a gap in the literature. In total, 23 horses were assigned to a stable with a central corridor and solid external walls (A) (N = 8), a stable with one side corridor and solid external walls (B) (N = 6), or a stable with a central corridor and no solid external walls (C) (N = 9). Air velocity, relative humidity, air temperature, and noxious gases were measured inside the stables, and the heart rate and HRV of the horses were also determined. The relative humidity was lower in stable C than in stable A (p < 0.05), while the air temperature was higher in stable C than in stable B (p < 0.05) during the day. The airflow and ammonia levels were higher in stable C than in stables B and A (p < 0.01–0.0001). Overall, horses’ HRV in stable A was lower than in those in stables B and C (p < 0.05–0.01). Horses in stable A tended to experience more stress than those in other stables.

Airflow plays a crucial role in plant growth because it supplies CO2, O2, and energy to plants in a plant factory with artificial light (PFAL). Therefore, understanding how various factors affect airflow in and around a plant canopy is essential. In this study, we developed a computational fluid dynamics (CFD) model with realistic plant structures created using structure-from-motion imaging to investigate airflow in and around a plant canopy. The averages of the absolute percentage errors of simulated air velocity in three conditions were 6.7%, 10.1%, 12.7%, respectively. The simulated and measured air velocities agreed well, confirming the accuracy of the developed CFD model. The effects of inflow velocities and plant canopy structures on the airflow in and around the plant canopy were analysed using the validated CFD model. The inflow velocities significantly decreased stagnant zones (from 62.4% to 7.2%) and increased the airflow uniformity in and around the plant canopy. A staggered layout of the plant canopy slightly decreased stagnant zones (from 16.4% to 13.2%) and increased the airflow uniformity. The airflow in and around the plant canopy was further inhibited by a large plant structure. This CFD model provided a basis for improving the airflow status in and around a plant canopy in a PFAL.

It is essential to investigate the dispersion of a large amount of toxic and harmful smoke in coal mine network during belt fires. A real-size model of an underground space was used to study the additional thermal resistance of single roadway and the dispersion characteristics of CO in bending structure, as well as the effect of air velocity on CO dispersion. The results show that the resistance of high temperature air flow is related to the ventilation resistance of the roadway under normal airflow, and is proportional to airflow temperature. The additional thermal resistance increases first and then decreases with time, and curve trend is similar to multiple “humps” with the increase of distance, which indicates that temperature is dominant factor. The distribution of CO is V-shaped at 90° corner, and the distribution pattern is unaffected by corner number. The increase of the air velocity destroys the CO distribution at the initial corner, and the air vortex zone appears at the bottom of the roadway. Meanwhile, the smoke flow diffused to the working face shifts from the outer wall to the inner wall of the working face. The results are helpful for selecting emergency evacuation areas and implementing safe measures.

The present study has been carried out to optimize the cabinet drying conditions using Response Surface Methodology (RSM) for drying moringa leaves. Moringa leaves were dried by a cabinet dryer using different drying temperatures 40–70 °C and air velocity 1.3–1.65 m/s. A central composite design was applied to optimize the drying conditions. The combined effect of these variables on the responses (moisture content, L*, a*/b* value, and vitamin C) was investigated. The findings show that the generated regression models effectively captured the real link between the independent variables and the outcomes as well as sufficiently described the variation in the data. The moisture content, L* value, a*/b* value, and vitamin C content of dried moringa leaves were 3.76–8.30%, 42.17-45.39, −0.498 to −0.581, 10.50–19.57 mg/100g, respectively. The study found that the maximum vitamin C content was 19.57 mg/100g at 33.7 °C and 1.45 m/s air velocity. On the other hand, minimum moisture content was found 3.76% at 76.2 °C and 1.45 m/s air velocity. The optimum conditions for maximization of vitamin C and minimization of moisture content were the drying temperature and air velocity of 40 °C and 1.45 m/s, respectively. Moisture content, L*, a*/b*, and vitamin C content at optimum conditions were 6.282%, 44.282, −0.536, 17.711 mg/100g, respectively. Therefore, the current study suggests that the derived model is suitable for the enhanced retention of color ratio, lightness, and vitamin C content with a longer shelf life, which can afterward be practical in large-scale production in the food industry.

Industry processes require large amounts of energy inputs and often generate high temperatures exit gases that can potentially serve as secondary sources of energy. Waste heat recovery offers an opportunity for energy conservation that deserves more attention in the current global effort. Recovery of such waste heat can result in substantial reductions in net energy demand. Based on these objectives, this report describes the result of an experimental study that used solid particles in a vertical riser to recover gas energy from hot air through co‐current contact with solid particles. To study the hydrodynamic aspects of the riser section, this study utilized a fabricated experimental apparatus similar to the vertical duct used in the cement industry. The purpose of this study is to collect hydrodynamic data because there is limited information available about these aspects in the literature. A metallic fluid particle heat exchanger has been investigated through experiments. Various sizes of quarry dust and iron ore particles are studied in the present study. An empirical correlation is used to fit the mixing length (LA) determined at different parametric levels (gas velocity, particle size, solid feed rate, and solid density). Experimental correspondence for mixing length or LA is given as LAdt=5.1875dpdt0.1837wswg−0.1374ugμgdt2gρg0.3015ρpρg0.3961. The constructed experimental setup demonstrates a suspension preheater (SP) used in modern cement plants, but the correlation can be extended to a variety of other industries where waste heat recovery is feasible. [ABSTRACT FROM AUTHOR]

This study utilizes a simplified two-dimensional time-dependent computational fluid dynamic (CFD) model to compare the performance of single- and two-layer air curtains in an open-type multi-deck refrigerated display cabinet. Two layers of air curtain generate a more effective invisible barrier from ambient air impact that can reduce electrical energy consumption and maintain a uniform temperature distribution within the cabinet. The CFD model of a refrigerated display cabinet was validated by the experimental data. The results showed a two-layer air curtain advantage over a single air curtain. Electrical energy consumption decreased by 18.5%, and the average temperature of the test products decreased from 5.75 °C to 5.17 °C. The results obtained are important for cabinet design to improve the quality of product storage and reduce energy consumption. [ABSTRACT FROM AUTHOR]

This article is directed on increase of the premise ventilation efficiency by using linear diffusers. The aim of the work was to carry out theoretical research, experimental investigations and numerical modeling of the linear diffuser air dynamic characteristics, to obtain the graphs and analytical equations for determination of the linear diffuser necessary parameters and to encrease of efficiency air distribution in the room. Graphs of air velocity dependence on current coordinate and plates angle have been created and approximated by empirical equations. There was established that air velocity decreases intensively with increasing current coordinate and decreases with increasing of the plates angle. [ABSTRACT FROM AUTHOR]

To simulate the indoor air distribution accurately and quickly, this paper proposed a turbulence calculation model based on the zero-equation model and the SUPG finite element method. The optimal calculation parameters were investigated. The effects of air outlet positions, Reynolds numbers, and obstacle positions on indoor air distribution were studied. The results show that the ranges of Reynolds numbers which satisfy the summer and winter demands of indoor air velocity as the outlet at the right down position are larger than those when the outlet locates left down. When the air outlet locates at the left down position, the velocity non-uniformity coefficients are less than those under the other two conditions. Regardless of whether the air outlet is at the left or right position, the obstacle in the middle of a room can lead to worse velocity uniformity when air velocities in the working zone can meet the velocity demand. [ABSTRACT FROM AUTHOR]

During rescue operations, one of the important parameters determining the effectiveness of the implementation of tactical mechanical ventilation is the selection of the appropriate size of the outlet opening. The objective of this article is to determine the effect of the size of the discharge opening area (0.24–1.2 m2) and other factors on the obtained flow parameters (flow velocity, volumetric flow rate and static pressure value) generated by the two tested positive pressure ventilators. The volumetric flow rate was determined by measuring the flow velocity at appropriately selected measurement points. Two ventilator units were tested (one was the conventional type, while two were turbo). During the tests, the fans generated a flow of 4624.17 m3/h to 14,020.92 m3/h (the first—conventional type) and 4884.66 m3/h to 15,656.33 m3/h (the second—turbo type). The analysis carried out in the article can be used as a guideline for designers of buildings, with particular emphasis on cases in which the staircase is not directly adjacent to the façade wall (an escape route built into the axis of the building). [ABSTRACT FROM AUTHOR]

Porous materials are able to exchange moisture with the surrounding air. The more hygroscopic they are, the more they contribute to regulate ambient humidity. This ability is characterized by the moisture buffer value (MBV) which is measured under dynamic solicitations according to different protocols. The NORDTEST protocol is the most commonly-used. It gives recommendations regarding the air velocity and the ambient conditions for initial stabilization. The purpose of this article is to measure the MBV according to the NORDTEST protocol and to study the effect of air velocity and of initial conditioning on the MBV results for different materials. Two mineral and two bio-based materials are considered: gypsum (GY), cellular concrete (CC), thermo-hemp (TH) and fine-hemp (FH). Following the NORDTEST classification, GY is a moderate hygric regulator, CC is good, TH and FH are excellent. When the air velocity ranges from 0.1 to 2.6 m/s, the MBV of GY and CC materials remains constant, but the MBV of TH and FH materials is highly affected. The initial conditioning has no effect on the MBV, but has an effect on the water content of the material, whatever the material. [ABSTRACT FROM AUTHOR]

The article is devoted to solving of urgent problem: creation of staff work safety in the boiler room due to ensure of required conditions by natural ventilation. The aim of the work is to eliminate the main damage of the natural ventilation system of the boiler premise by using of compact air jet due to correction coefficients and updated results. Static and dynamic air pressure, difference of static pressure due to wind, aerodynamic coefficients and air balance for necessary nature ventilation of the boiler premise as well temperature correction coefficient are established. The update calculation dependencies for determining of the air static pressure and its volume flow rate in the boiler room have been obtained. Updated graph, monogram, and analytical equations for natural ventilation calculation of boiler room are presented. [ABSTRACT FROM AUTHOR]

ABSTRACT This study proposes automating an air conditioning system for drying and storing agricultural products. The main objective is to precisely control key parameters of the air, namely temperature, relative humidity, and air velocity, to optimize the drying process. The framework required for constructing and operating the automated air conditioner is explained in detail. Specifically, we describe the conditioning unit, the automation hardware, the control strategies employed to regulate temperature, relative humidity, and air velocity, and discuss the safety measures and human-machine interfaces of the system. Experimental validation of the proposed system is presented, along with results and discussions demonstrating its successful control of drying air parameters across a wide range of desired conditions.

To delay frost formation and maintain high heat transfer capacity of an evaporator, a closed-loop wind tunnel was designed and constructed to investigate the effect of heat exchange temperature difference (ΔT) and air velocity on frost formation characteristics, refrigerating capacity and water removal of air. The closed-loop wind tunnel provided flowing air at temperature of −18 °C, relative humidity of 85% and velocity from 2 to 5 m/s. During experiment, three obvious stages of frost thickness were found when air initial velocity was 3–5 m/s. With ΔT changing from 7 to 3 °C, the water removal of air through the evaporator decreased by 3–5 times and the high efficient operation time ratio (HETR) increased by 2–3 times. Meanwhile, the average frost mass reduced by about half at any fixed air velocity. When ΔT was 7 °C and air velocity was 2 m/s, the average refrigerating capacity was almost equal to that when ΔT was 3 °C and air velocity was 5 m/s. The combined results showed that smaller ΔT and larger air velocity was useful to forbid frost formation, and to maintain stable high refrigerating capacity and relative humidity.

A humid environment decreases the performance of induced draft counter flow cooling towers (IDCFCT) normally used in power plants and process industries. The primary objective of this study is to experimentally analyze the effect of using rotary silica gel mesh (RSGM) on the performance of IDCFCT. Experimental setups of IDCFCT with and without RSGM have been designed and fabricated to perform the comparative analysis. The performance of both cooling towers (CTs) in terms of output temperature, relative humidity of air, range, approach, and effectiveness at different air velocities has been investigated. The results indicate that the outlet air temperature of IDCFCT integrated with the RSGM wheel is 0.5–1.5°C higher than the IDCFCT without the RSGM wheel. IDCFCT with RSGM wheel shows maximum effectiveness of 0.67 at an air velocity of 1.5 m/s and inlet water temperature of 55°C; whereas, for IDCFCT without RSGM wheel, it is only 0.54. In terms of efficiency, RSGM wheel integrated IDCFCT shows an improvement of 24% compared to IDCFCT without RSGM wheel. It has been observed that RSGM‐integrated IDCFCT also helps to save water up to 431.7 kg/h at an air velocity of 1 m/s with a water inlet temperature of 35°C. Moreover, the advantage of integrating the RSGM wheel with IDCFCT has been further corroborated in terms of the reduction in the height of the CT obtained with the help of a thermodynamic model. [ABSTRACT FROM AUTHOR]

The main purpose of any vehicular climatic control in terms of heating and air conditioning (AC) systems is to achieve maximum thermal human comfort with energy efficient. Therefore, it is important to analyse the temperature distribution and air-flow field in the cabin compartment to achieve the highest and rapid human comfort. This paper adopted a Berkeley human comfort model to show the behaviour of a vehicular human sensation and comfort at different airflow velocity levels. A temporal history, local sensation (LS), and comfort (LC) were analysed for different body segments with the addition of the overall sensation (OS) and the overall comfort (OC) inside the passenger compartment under summer period weather conditions. This study revealed that: because of the air velocity plays crucial impacts on both convection and evaporation mechanisms which directly effects on the heat losses from the body and thermal human comfort, the controlling of air movement with the temperature helps the environmental cabin to achieve the comfort zone faster than the sole control of the temperature only. When activated the air conditioning systems, the vehicular environmental parameters will change dramatically and a rapid transient occurred especially in the first few minutes. [ABSTRACT FROM AUTHOR]

A cooling coil is an integral part of an air-conditioning system. Chilled fluid flows through the coil and the incoming air gets cooled and dehumidified as it comes in contact with the coil. However, a portion of the incoming air bypasses the coil and that, in turn, results in the final psychometric condition of the air. In this paper, experiments are performed to quantify the cooling coil performance under changing conditions. Change in weather plays a significant role in influencing the performance of the coil. The effect of the change in inlet opening is also important. A thorough investigation through regular experimentation is done to measure the variability in performance. A multivariate nonlinear regression analysis is done to see the relation of the coil performance to the input variables. The results indicate an ascending trend of bypass factor with a gradual rise in the air temperature at different inlet openings. Besides, the dependence of the coil performance on moist air properties, e.g., relative humidity, is also analyzed. Moreover, higher values of air velocity uplift the bypass factor, indicating lesser capability of cooling. [ABSTRACT FROM AUTHOR]

Hot air impingement drying (HAID) was employed to dry Amomum villosum (A. v.) fruit, one of the most popular traditional Chinese herbs and functional foods, under different drying temperatures, air velocities and the drying characteristics and quality were evaluated. The drying time decreased from 12 to 4 h, 10 to 8 h with the increase of temperature and velocity from 50 to 70 °C, 3 to 9 m/s, respectively. Weibull model precisely described the drying behavior. The highest total flavonoid content was obtained at 60 °C with low shell burst ratio. As for essential oil components, the relative content of monoterpenoids increased while sesquiterpenes decreased with increasing temperature. The acids and alcohols contents decreased with increase in velocity. By considering both drying time and quality, 60 °C and 6 m/s was proposed as the most favorable condition. The findings indicate HAID is a promising drying method for A. v. fruit. [ABSTRACT FROM AUTHOR]

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Cooling towers have such a significant influence on work and efficiency that researchers and designers are working tirelessly to enhance their performance. A prototype design for a natural draft hybrid (wet/dry) cooling tower has been created, relying on geometrical, dynamic, and thermodynamic similarities. Based on Iraqi weather, experiments have been conducted using splash fill (150 mm) in summer (hot and dry) weather conditions. This study investigated heat transfer mechanisms of both air and water in a natural draft hybrid cooling tower model(NDHCTs), both directly (wet section) and indirectly (dry section). The tower is filled with splash-style packing, and the warm water is spread throughout the building using sprayer nozzles. The influences of water flow rates, fill thickness, and air velocity on the cooling range, approach, cooling capacity, thermal efficiency of the cooling tower, water evaporation loss into the air stream and water loss percentage were explored in this study. The experimental were carried out with four different water flow rates, ranging from 7.5 to 12 (Lpm) litres per minute, and eight different air velocities, all while keeping a constant inlet water temperature and a zero (m/s) crosswind. Data has been gathered, and performance variables have been determined. The findings demonstrate that the cooling tower's efficacy increases when the water flow rate is low, and the cooling range increases with increasing air velocity and decreases with increasing water flow rate; for a 7.5 Lpm water flow rate and a 2.4 m/s air velocity, it expanded to 19.5 ℃. The cooling capacity increased to 23.2 kW for a water flow rate of 12 Lpm and an air velocity of 2.4 m/s.

The article is devoted to solving of urgent problem to analyse energy saving effect from radiant heating and ventilation of premise with exhaust outlet and flat decking air jet. The aim of the work is analysis of energy efficiency of radiant heating systems using infrared heaters and ventilation of the premise due to the effect of a flat decking air jet on the surface of the heater; determination the amount of heat received both by flat decking air jet from the infrared heater when laying on its flat surface and amount of heat from the exhaust air entering the recuperator. Use of the infrared heaters in combination with an air distribution of the ventilation system with the flat decking air jets is effective, as it allows to achieve savings in heat load of the ventilation system in the range of 11% - 19%. The amount of heat recovery of the exhaust air removed by the exhaust outlet is 30 - 40 W that equals 15% - 20%. Saving the heat load of the ventilation system allows reducing the actual initial temperature of the tidal flat decking air jet and achieving a total saving of thermal energy of 24% - 34%.

• Ventilated roof thermal performance is analyzed by multi-field coupling COMSOL method. • An optimal air velocity exists in air cavity to obtain a better roof thermal performance. • Roof thermal performance with air vents is better than that without air vents. • Thermal performance of ventilated roof can be enhanced by air deflectors and solar panels. • Optimal layout and design parameters are presented for the ventilated roofs. Building roofs play a pivotal role in energy conservation and carbon reduction of buildings due to their high peak heat gain and large roof area. However, the optimal layout and design parameters for ventilated roofs is not very clear. In this study, the influences of air vents, air inlet and outlet sizes, air velocity in the air cavity, solar panels, and air deflectors on the thermal performance of ventilated roofs were numerically investigated using a new thermal-flow-solar radiation coupling simulation approach and an experimentally validated COMSOL model. The research results show that a ventilated roof structure with air vents has a better thermal performance than that without air vents. The air velocity range of the air inlet between 1 m/s and 1.5 m/s shows a better energy-saving effect than the other air inlet velocities. The thermal performance of the ventilated roof first increases and then reduces as the air inlet and air outlet size increases. An optimal air velocity exists in the air cavity to obtain a better roof thermal performance. A ventilated roof structure with an air deflector exhibits better thermal performance than that without an air deflector. The larger the percentage of solar panel area to the roof area, the greater the energy savings of the ventilated roof. Thermal performance of ventilated roofs can be enhanced by using air deflectors and solar panels. The findings of this study can provide valuable suggestions for optimizing the design and assessing the energy saving-effects of ventilated roofs. [ABSTRACT FROM AUTHOR]

Airflow parameters play a vital role in regulating the microclimate of the plant canopy and significantly affect plant development and growth in plant factories with artificial light (PFALs). A computational fluid dynamics (CFD) model with a realistic soybean canopy was developed to predict the distribution of radiation (W m−2), leaf temperature (°C), air velocity (m s−1), air temperature (°C), and relative humidity (%) within a plant canopy. The accuracy of the CFD model was confirmed by comparing mean absolute percentage errors of these variables which were 9.9 %, 1.4 %, 11.4 %, 0.8 %, and 1.8 %, respectively. The validated CFD model was used to simulate the lamp temperature and microclimate distribution of the soybean canopy under different inflow parameter levels on a cultivation shelf. The results revealed that the microclimate was primarily influenced by lamp radiation rather than convective heat when the inflow velocity was below 0.57 m s−1. Inflow velocity, air temperature, and relative humidity exerted more significant effects on air velocity, air temperature, and relative humidity, respectively, than the other variables in the plant canopy. The increase of inflow velocity significantly improved the uniformity of air velocity, temperature, and relative humidity in the plant canopy. However, note that this study investigated the lamp temperature and microclimate distribution in plant canopies under different airflow parameters using the CFD model without coupling plant transpiration to the surrounding climate. This provides valuable insights into the control of the plant canopy microclimate in general and more particularly on the shelves of PFALs. [Display omitted] • CFD model with realistic plants was developed to simulate plant canopy microclimate. • A realistic plant model is established using structure-from-motion imaging. • The coupling of convective and radiative heat transfer from lamps was analyzed. [ABSTRACT FROM AUTHOR]

ABSTRACT: This study determined the effects of increasing ambient temperature (T) at different relative humidity (RH) and air velocity (AV) levels on the physiological and productive responses of dairy cows. Twenty Holstein dairy cows were housed inside climate-controlled respiration chambers, in which the climate was programmed to follow a daily pattern of lower night and higher day T with a 9°C difference, excluding effects from sun radiation. Within our 8-d data collection period, T was gradually increased from 7 to 21°C during the night (12 h) and 16 to 30°C during the day (12 h), with an incremental change of 2°C per day for both nighttime and daytime T. During each research period, RH and AV were kept constant at 1 of 5 treatment levels. A diurnal pattern for RH was created, with lower levels during the day and higher levels during the night: low (RH_l: 30–50%), medium (RH_m: 45–70%), and high (RH_h: 60–90%). The effects of AV were studied during the day at 3 levels: no fan (AV_l: 0.1 m/s), fan at medium speed (AV_m: 1.0 m/s), and fan at high speed (AV_h: 1.5 m/s). Effects of short and long exposure time to increasing T were evaluated by collecting data 2 times a day: in the morning [short: 1 h (or less) − exposure time] and afternoon (long: 8 h − exposure time). The animals had free access to feed and water and both were ad libitum. Respiration rate (RR), rectal temperature (RT), skin temperature (ST), dry matter intake, water intake, milk yield, and composition were measured. The inflection point temperatures (IPt) at which a certain variable started to change were determined for the different RH and AV levels and different exposure times. Results showed that IPt under long exposure time for RR (first indicator) varied between 18.9 and 25.5°C but was between 20.1 and 25.9°C for RT (a delayed indicator). The IPt for both RR and RT decreased with higher RH levels, whereas IPt increased with higher AV for RR but gave a minor change for RT. The ST was positively correlated with ambient T and ST was not affected by RH but significantly affected by AV. For RR, all IPt was lower under long exposure time than under short exposure time. The combination of higher RH levels and low AV level negatively affected dry matter intake. Water intake increased under all treatments except RH_l-AV_l. Treatment RH_h-AV_l negatively affected milk protein and fat yield, whereas treatments RH_m-AV_m and RH_m-AV_h reduced milk fat yield. We concluded that RH and AV significantly affected the responses of RR, RT, ST, and productive performance of high-producing Holstein cows. These responses already occurred at moderate ambient T of 19 to 26°C.

The use of phase change materials (PCMs) in building enclosures is an efficient way to reduce the heat gain and/or loss in summer and winter. It was evident that the thermal performance of buildings with PCMs was affected by the outdoor air temperature significantly. However, the influence of humidity, which was serious in the humid subtropical climate was unclear. To explore the effect of PCMs under a humid subtropical climate, the thermal performance of a lightweight building outfitted with PCMs with a melting temperature of 25 °C was investigated. The actual outdoor air temperature with a humidity of 40–90 RH% and wind velocity of 2–6 m/s blowing from the east, west, south, and north was assumed for the performance assessment. A simulated model was developed using EnergyPlus and verified against experimental data. The energy savings by using PCMs was reduced from 3.9% to 2.6% when the outdoor humidity increased from 40 to 90 RH% in summer. However, the savings was not obvious in winter. Annual energy savings decreased from 1.64% to 1.32% with humidity increasing from 40 to 90 RH%. For annual condition, the average energy savings was reduced from 1.43% to 0.92% when the wind speed increased from 2 m/s to 6 m/s. From an economic point of view, the investment payback period was less than 10 years when the PCM price was lower than 18.0 Yuan/kg.

The article is devoted to solving of urgent problem to eliminate damage in ventilation system. That is caused by non-adequate long range, stagnant unventilated areas in the room existance and high noise level in the premises at air distribution by swirled air flow, compact air jet, flat air stream and rectangular air jet. A noise level of air supply with swirled air flow, compact air jet, flat air jet and rectangular air stream in the room has been investigated. It is shown that in order to achieve the maximum noise level decreasing it is necessary to ensure its supply by jets, which less intensively attenuate before entering the premise working area. Results of the experimental research are presented as graphical and analytical dependences. The acoustic properties of the swirled air flow, compact air jet, flat air stream and rectangular air jet have been investigated and means of situation improving have been determined. The results of experimental research of air supply to the room are presented. It is established that with the increase of the angle of swirling plates inclination and ratio of the slit sides the air jets noise level decreases.

Due to the broiler house's needs for a healthy environment, efficient control system, and appropriate air, several studies were interested in microclimate and air quality characteristics. However, limited studies are conducted to investigate pressure and air velocity within poultry buildings, which are also significant parameters that impact the breeding environment and productivity. As a reason, the objective of this work was to develop a mathematical model exploring the differential pressure and air velocity inside the house. The peculiarity of this research is the use of thermal balance and air properties to propose a model related to birds' weight which can be translated to birds' age and thermal conditions. The proposed approach acquired experimental measurements (e.g., indoor air temperature and humidity, air velocity, and differential pressure) and performed simulations in a mechanically ventilated Mediterranean broiler house over a summer production cycle. The findings revealed that the observed and modelled differential pressure ranged from a negative to a positive pressure (−5 to 39 Pa), with broilers subjected to air velocity varying from 0.09 to 1.641 m s−1 depending on three distinct modes of regulation: nature, power, and tunnel mode. These results confirmed the model's predictive capacity with a relative error of 1.03% of differential pressure and 0.68% of air velocity and a normalised mean square error (NMSE) of −1.06 Pa and 0.19 m s−1, respectively. Consequently, the methodology applied in this paper may be extended to various species of breeding structures in other seasons, allowing simulation tools and system control improvement.

Deposition of the 222Rn (radon) and 220Rn (thoron) progeny on surfaces is one of the important processes that reduces the progeny activity concentration and hence inhalation dose in the indoor as well as occupational environment. Deposition of 222Rn/220Rn progeny on surfaces is characterized by the term effective deposition velocity ( V e ) which is highly influenced by parameters like air velocity, aerosol concentration (Z) and Relative Humidity (RH) etc. prevailing in any real indoor or occupational environment. In the present study, behavior of V e of both 222Rn and 220Rn progeny for varying environmental conditions were studied by simulating these conditions in an 8 m3 calibration chamber. It was observed that both 222Rn and 220Rn progeny behave in a similar manner with respect to the environmental parameters. With increase in air velocity, V e of both 222Rn and 220Rn progeny was found to be increased, whereas, with increase in Z and RH, V e was observed to be decreased. The experimentally obtained values of V e were compared against the theoretical model calculation which showed good agreement. Measurement of V e was also carried out in an occupational environment with varying humidity conditions and was found to agree well with the theoretical as well as the experimental values of V e in controlled calibration chamber. [ABSTRACT FROM AUTHOR]

The comfort issue touches several domains such as the psychic and the physical, like olfactory, visual, and thermal comfort. The latter has a strong relationship with the outdoor public space, because thermal well-being defines the quality of life of the user. In this perspective, our work is conducted to identify the impact of different thermal factors and conditions on the microclimate. Furthermore, it aims to study the difference between the microclimatic parameters influencing thermal comfort in outdoor public spaces, and those taken from the meteorological station. The method adopted for this research is based on the comparison between the climatic data recorded in the meteorological station of the airport "Rabah Bitat" of Annaba, that it is located in a low concentration urban environment, and the climatic measurements taken in various stations in the areas of studies (revolution course, square of el Houria, Boukhatouta Houcine garden), which are located right in the city center, using a thermal hygrometer, and a thermo-anemometer. These data represent the measurements of an average of 03 typical summer days in August. The results obtained confirm the difference between the thermal comfort in an urban environment and the thermal environment in a low urban environment. [ABSTRACT FROM AUTHOR]

In this work, the actual aspect of the creation of comfortable climatic conditions indoors due to the compressed swirl compact air streams at an alternating mode is considered. The purpose of this article is the mathematical modeling of the swirl compact air jet and getting of the analytical equations for calculation air distribution in a premise at the condition of dynamic indoor climate in compressed conditions of a premise for providing comfort people well-being. A mathematical model of air supply with the swirl compact air jets in the room has been developed. A combinatorial-logarithmic method for the graphs approximating the dependence of the relative transverse velocity of a swirl compact air jet and the correction coefficient for compression and swirling on the relative transverse coordinate has been developed. [ABSTRACT FROM AUTHOR]

Over the past few decades, the spontaneous combustion of large-scale coal stockpile is frequent due to natural airflow contacted the surface and entered in the voids of coal stockpile, coal is oxidized and accumulated the heat, and then coal spontaneous combustion occurred, which seriously caused the waste of natural resources and environmental pollution. In this study, based on the principle of heat transfer by heat pipe (HP), an experiment is conducted to study the effect of heat transfer by HP, such as the temperature difference and heat transfer ratio, heat transfer radius, cumulative heat transfer volume, in a coal stockpile as its heating temperature increased from 100°C to 150°C under the different lab conditions. The results indicated that the average temperature drop scale in the coal stockpile by HP was 46.3%, 10.8%, and 32.8% that under the lab conditions, respectively. A comparison study revealed that as the inserted angle of HP in the coal stockpile is 60º, the heat transfer effect of HP is significantly affected by outside ambient, especially sensitive to airflow. For instance, as the HP inserted scale is 1:4, outside air velocity is 2.0 m/s, the maximum heat transfer radius in the coal stockpile is 49.2 cm, the overall heat transfer effect enhanced by 79% and 93% that with the heating temperature in the coal stockpile is 100°C and 150°C, respectively. Therefore, it can be concluded that the utilization of HP is a reasonable method to remove the accumulated heat in the coal stockpile, as well as the suitable arrangement is also significantly important before this technique is conducted. This study provided a new technical approach and theoretical basis for the prevention and control before the large-scale stockpile has the risk of spontaneous combustion. [ABSTRACT FROM AUTHOR]

This study utilizes a simplified two-dimensional time-dependent computational fluid dynamic (CFD) model to compare the performance of single- and two-layer air curtains in an open-type multi-deck refrigerated display cabinet. Two layers of air curtain generate a more effective invisible barrier from ambient air impact that can reduce electrical energy consumption and maintain a uniform temperature distribution within the cabinet. The CFD model of a refrigerated display cabinet was validated by the experimental data. The results showed a two-layer air curtain advantage over a single air curtain. Electrical energy consumption decreased by 18.5%, and the average temperature of the test products decreased from 5.75 °C to 5.17 °C. The results obtained are important for cabinet design to improve the quality of product storage and reduce energy consumption.