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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.

This research aimed to study the temperature efficiency of vertical charcoal metal kiln compared between the original kiln and improved charcoal kiln with thermal insulation to prevent heat loss. The computational fluid dynamics (CFD) model was used for analysis. The improved charcoal kiln with thermal insulation to prevent heat loss to change airflow within kiln's chamber. Components of improved kiln consisted of; 1) The insulated cover lid made from fiberglass in cylindrical shape with thickness of 10 cm., height of 100 cm., and diameter of 65 cm., wrapped with steel sheet 2 mm. of thickness; 2) The metal combustion chamber in cylindrical shape, with 56 cm. of diameter, 89 cm. of height and 0.2 m3of capacity; 3) Metal grate placed 10 cm. inside the combustion chamber; 4) The kiln base for fuel input, with space for airflow to the chimney and for sand input in order to prevent heat loss while testing; and 5) The 4 inches pipe-shaped steel chimney, with thickness of 2 mm. and height of 200 cm. The computational fluid dynamics (CFD) model found that the maximum temperature was similar. When, it was compared the double layers vertical charcoal metal kiln to prevent heat loss with the original kiln, it was found that the average temperature was improved at 277.54°K, the charcoal kiln temperature efficiency was improved at 51.47 percentage, the average air velocity was improved at 1.26 m/s, of which resulted from the change of airflow direction (stream line). [ABSTRACT FROM AUTHOR]

A pneumatic fertilization distributor used for fertilizing in a fertilizer applicator is a key component of the applicator. The parameters of a pneumatic fertilization distributor affect the uniformity and accuracy of the fertilization of a fertilizer applicator. To obtain the optimal design parameters of a pneumatic fertilization distributor, a fluidstructure coupling simulation test and a bench test were carried out in the Intelligent Agricultural Machinery Laboratory of the Nanjing Institute of Agricultural Mechanization from March 2021 to July 2022. The curvature–diameter ratios of the elbow, bellow length, and air velocity were selected as the experimental factors, and the variation coefficient of the fertilizer discharge at each discharge outlet within 0.5–3 s was selected as the experimental index. A five-level quadratic regression orthogonal rotation combined test was carried out. The results showed that: (1) all three factors had a significant impact on the uniformity of the fertilizer discharge. The reasonable ranges of the curvature–diameter ratio, bellow length, and air velocity were 0.5–1.5, 350–550 mm, and 25–35 m/s, respectively. (2) The order of the influence of the three factors on the uniformity of the fertilizer discharge in descending order was as follows: the curvature–diameter ratio of the elbow, the bellow length, and the air velocity. When the bellow length was 460 mm, the curvature–diameter ratio was 0.6, and the inlet air velocity was 28 m/s. The uniformity of the fertilizer discharge was optimal. A pneumatic conveying system was redesigned according to the optimal parameters, and a bench test was carried out. The results showed that at different speeds, the coefficient of variation of each row's displacement was not greater than 5%, and the simulation test results were consistent with the bench test results. [ABSTRACT FROM AUTHOR]

By using the commercial modelling software, a 3D model of the automotive radiator has been designed. A commercial CFD tool has been used for the numerical study of the radiator. The nanofluids are used as coolant with water to increase the cooling efficiency. Nanofluids such as aluminium oxide (Al2O3), copper oxide (CuO) and silicon carbide (SiC) are mixed with ethylene glycol and water to improve the cooling efficiency in this study. At constant temperature, the air velocity is varied from 20 m/s to 30 m/s. An average heat transfer coefficient of various nanofluids for the varied air velocity at constant temperature has increased when the nanofluids are added in the water/ethylene glycol based on the experimental data. As a coolant, silicon carbide nanofluid was shown to transfer the heat better than aluminium oxide, copper oxide, silver nitrate, iron oxide and ethylene glycol. Nusselt and Reynolds numbers have been shown to be higher. To achieve cooling efficiency, an increase in heat transfer with a change in air velocity is required. The cooling efficiency of the silicon carbide was increased up to 15% when compared to Al2O3 nanofluids. [ABSTRACT FROM AUTHOR]

This study uses a simplified two-dimensional time-dependent computational fluid dynamic (CFD) model to study the influence of wall shelf configuration and outtake honeycomb inclination angle on the performance of the air curtain in an open-type semi-vertical refrigerated display cabinet. Numerical simulation results show that changing the angle, along with changing the shelf configuration, can reduce the temperature of the intake air grille and improve the warm/cold air ratio. The average temperature of the simulated food products decreased by 1.2 °C compared to the unmodified display cabinet and began to meet the requirements of the temperature category 3M0. The proposed CFD model was validated by the experimental results. The simulation results obtained are important for cabinet design to improve product storage quality and reduce energy consumption. [ABSTRACT FROM AUTHOR]

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°C. 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. [ABSTRACT FROM AUTHOR]

The colour quality and functional activity of dried fruits are important quality indexes. The purpose of this study was to evaluate the effects of heat pump drying with different air velocity on browning‐related reactions and antioxidant activities of products and their storage counterparts. The results showed that apple cubes possessed different Maillard reaction levels, polyphenol and pectin variation, and antioxidant capacity, which could be controlled by different drying air velocity when the temperature is constant. In present work, high air velocity (2.0–2.5 m/s) drying (HHD) apple cubes possessed 22.58% more browning comparing to low air velocity (0.02–0.50 m/s) drying (LHD), which correlated with its 8.13 μg/g, 132.35 μg/g and 6.21% more of 5‐HMF, chlorogenic acid and DE level of pectin, respectively. Interestingly, the b value of HHD and LHD samples decreased after storage, which was related to the DE, GalA, structural properties (Ratio1, Ratio2 and Ratio3) and conformational properties (PDI, RG and RC) of pectin in samples. Besides, HHD treatment promoted higher DPPH and FRAP capacity than LHD, which significantly involved Mw of pectin. The research would provide a new insight from the perspective of pectin for regulating the browning and antioxidant activity in apple thermal process. [ABSTRACT FROM AUTHOR]

High population causes high food consumption so that the production of organic waste also increases. Waste processing is the process of transforming waste physically, chemically and biologically. Waste processing techniques can be in the form of composting, incineration, recycling, and biogasification. High water content in organic waste causes a decrease in combustion efficiency, therefore pretreatment is needed in the form of drying. The Tray dryer is one of the most widely used batch-type dryers due to its simple design and low construction cost. The non-uniformity of the final moisture content in the dried product is the main problem of the tray dryer. This study was conducted to determine the effect of the air distribution pattern and temperature and to analyze the characteristics of the tray dryer using Computational Fluid Dynamics software, namely ANSYS FLUENT. Simulations were carried out with variations in air velocity at the inlet of 1 m/s, 1.5 m/s and 2 m/s with an air temperature of 100°C. The results of the simulation of the distribution of air and temperature in the drying chamber are represented in the form of contours of air velocity, temperature and static pressure and show tha the temperature distribution evenly occurs at the inlet air velocity of 2 m/s. [ABSTRACT FROM AUTHOR]

Wind catchers used in various countries in Middle East and North Africa in order to improve indoor air environment and to reduce reliance on cooling load. However, nowadays they are used across the globe with modern shapes and advanced techniques. The study focuses on investigating new and innovative shapes of wind catchers to improve air speed indoors which will elevate indoor comfort and air quality in buildings. The study used computer modeling CFD and a real model experiment to conduct the study. The study highlighted that curved shapes have highest pattern of wind speed driven, especially curved shape with double inlets. In addition, the study showed that octagon shape has the lowest pattern of wind speed driven because of its various sides which prevent air to flow easily inside the tunnel.

Aim. To study the motor activity of sheep of the Zabaykal (Transbaikal) and Agin breeds in year‐round grazing in relation to the season of the year.Material and Methods. The research was carried out in the steppe zone of the Aginsky District of Zabaykalsky Territory. Garmin eTrex 20x GPS receivers were used in the research with the help of which motor activity and the speed of sheep in pasture were monitored. Weather conditions were taken into account for the relevant research periods using data from the meteorological service.Results. Average daily air temperature in winter was – 23.30°C, air velocity 1.3 m/s and relative air humidity 67.3%, and in spring was 13.70°C; 4.1 m/s and 35.6%, in summer – 20.90°C; 1.6 m/s and 77.3% and in autumn – 1.10°С below zero, 2.4 m/s and 50.1%. It was found that the sheep being monitored travelled different distances with different speeds of movement depending on the season of the year and origin. They travelled the greatest distance in winter with a higher average speed of movement and a shorter distance in the summer. At the same time, it was noted that semi‐coarse‐wooled (Agin) sheep passed 12378 m during the 8‐hour grazing period, which is 24.9% more than fine‐wooled (Zabaykal) sheep (Р˂0.01), in spring – 8,168 m (22.3% more, Р ˂0.05), summer – 6,511 m (24.5% more, Р˂0.01) and autumn – 9,214 m (40.3% more). The average speed of movement of semi‐coarse‐wooled sheep was higher than fine‐wooled by 80.0% (P˂0.05), 25.0, 9.1 and 23.1% (P˂0.05), respecƟvely. The nutritional value of 1 kg of dry matter of pasture grass was higher in the summer and amounted to 0.68 units with a content of 1 unit 93.1 g of digestible protein. Conclusion. The research data allow us to conclude that the motor activityand the speed of movement of sheep in pasture directly depends on the season of the year and the nutritional value of pasture grass, as well as on type of breed.

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).

This study delves into the complexities of frost formation on road surfaces, a phenomenon that presents significant safety hazards in transportation due to its sudden emergence and unpredictable nature. Despite advanced meteorological warning systems for snowfall and freezing rain, black ice and frost remain difficult to predict and counteract. To address this, a controlled indoor simulation experiment was designed to investigate the characteristics of road surface frosting at low temperatures. Results from the experiment indicated that growth of the frost layer thickness follows a parabolic trend with extended freezing time yet the mass of the frost layer increases at a roughly linear rate. The data also revealed that lower temperatures expedite the phase transition of water vapor to ice, leading to faster increases in frost layer height. Additionally, the effects of air temperature and velocity on frost properties were examined. Interestingly, higher air temperatures facilitated rapid frost formation initially, but later stages displayed a plateau phase in the rate of accumulation. Furthermore, increased air velocity up to 1 m/s resulted in greater frost mass, but higher velocities diminished frost formation due to enhanced heat transfer. In conclusion, this study offers a detailed analysis of frost layer development under controlled conditions, providing valuable insights into the environmental factors influencing this hazardous phenomenon. The findings contribute to the understanding of frost dynamics on road surfaces, with implications for improving predictive models and developing effective countermeasures for road safety during icy conditions. • An indoor simulation experiment reveals the parabolic growth of road surface frost layer thickness and a roughly linear increase in mass over time. • Lower temperatures significantly expedite the phase transition from water vapor to ice, hastening the vertical growth of frost layers on road surfaces. • Air temperature and velocity are found to have a nuanced effect on frost formation, with higher temperatures initially promoting rapid accumulation. [ABSTRACT FROM AUTHOR]

Simple Summary: Inappropriate eliminating on a resting area has a negative effect on the environment, the cleanliness of pigs and pens, and can impair farm productivity. There are several factors that can affect pig eliminative behaviour. The primary aim of this survey was to investigate which factors related to the physical environment have the strongest effects on pig and pen cleanliness and ammonia concentration. Secondly, we wanted to assess the relationship between ambient temperature, air velocity and cleanliness of the pen and the pigs and ammonia concentration. Data were collected from 87 pig farms (n = 5769 pigs; n = 643 pens). The larger the eliminative area and resting area, the cleaner were the pigs. The eliminating area could have open partitions and be placed in the back of the pen. The resting area with a large amount of litter on the floor and use of straw as rooting material increased the cleanliness of this area. A more optimal pen design, such as that described in the present study, can reduce the workload for the farmers (cleaning), improve air quality, and lower the environmental footprint. There are several environmental and ambient factors that can affect pig eliminative behaviour. The aim of this survey was to investigate factors related to the physical and ambient environment that have the strongest effects on pig and pen cleanliness and ammonia concentration. Data were collected from 87 pig farms and analysed using mixed (ammonia concentration) or generalized linear (pen and pig cleanliness) model in SAS. The pen was cleaner when pen partitions were open compared to closed (p = 0.010) and increased with increasing amount of litter (p = 0.002), using straw (p = 0.002) as rooting material. Pig cleanliness was higher when pen partitions in the eliminative area were open compared to closed (p = 0.007) and increased with increasing space per pig in the resting area (p < 0.001), with decreasing temperature (p < 0.001), and lowering of air velocity (p = 0.003). Other factors that increased cleanliness was using straw as rooting material (p = 0.028) and increasing amount of litter in the resting area (p = 0.002). Ammonia concentration was reduced with increasing floor space in the eliminative area (p < 0.001) and increasing amount of litter (p = 0.006). Our results pinpoint physical and ambient conditions affecting pen and pig cleanliness and air quality. [ABSTRACT FROM AUTHOR]

Measurements of air flow velocity are essential at every stage of the design, construction and operation of wind turbines. One of the basic measurement tools in this area is the tachometric anemometer, which is based on the simple physical phenomenon of the air kinetic energy exchange with a rotating measuring element. Tachometric anemometers have favorable operational features and good static metrological parameters. However, in the case of fast-changing flows, the measurement is burdened with a significant dynamic error, and the measured average value of the velocity is overestimated. This article presents the concept and results of pilot studies of a dynamic error correction method of tachometric anemometers. The correction consists of the precise measurement of the rotor's rotational velocity and determination of the measured air velocity, taking into account the dynamics of the instrument. The developed method can be used in tachometric anemometers intended for laboratory, technical and industrial measurements in time-varying flows. One of the important application areas is the measurement of wind energy. [ABSTRACT FROM AUTHOR]

Simple Summary: Behavioral changes are one of the mechanisms for broilers to adjust their body temperature under heat stress conditions. However, the behavioral responses of heavy broilers to environmental changes have not yet been studied well. Therefore, this research investigated the behavioral changes of broilers under two dynamic air velocity treatments (high and low) under summer conditions. Video data collected from a heat stress experiment conducted on broilers aged 42–54 days were used to investigate variations in the number of chickens feeding, drinking, standing, walking, sitting, wing flapping, and leg stretching. The results indicated that the high air velocity treatments increased the number of chickens feeding, standing, and walking. In addition, age significantly affected the number of birds feeding, drinking, panting, and sitting, while the time of the day also affected the number of chickens drinking and panting. This study reveals the thermal stress of heavy broilers from their behavior under summer conditions to help manage the performance and welfare of birds under environmental stress. Broiler chickens exposed to heat stress adapt to various behavioral changes to regulate their comfortable body temperature, which is critical to ensure their performance and welfare. Hence, assessing various behavioral responses in birds when they are subjected to environmental changes can be essential for assessing their welfare under heat-stressed conditions. This study aimed to evaluate the effect of two air velocity (AV) treatments on heavy broilers' behavioral changes from 43 to 54 days under summer conditions. Two AV treatments (high and low) were applied in six poultry growth chambers with three chambers per treatment and 44 COBB broilers per chamber from 28 to 61 days in the summer of 2019. Three video cameras placed inside each chamber (2.44 m × 2.44 m × 2.44 m in dimension) were used to record the behavior of different undisturbed birds, such as feeding, drinking, resting, standing, walking, panting, etc. The results indicate that the number of chickens feeding, drinking, standing, walking, sitting, wing flapping, and leg stretching changed under AV treatments. High AV increased the number of chickens feeding, standing, and walking. Moreover, a two-way interaction with age and the time of day can affect drinking and panting. This study provides insights into heavy broilers' behavioral changes under heat-stressed conditions and AV treatments, which will help guide management practices to improve birds' performance and welfare under commercial conditions in the future. [ABSTRACT FROM AUTHOR]

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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%. [ABSTRACT FROM AUTHOR]

As a result of COVID-19, many office buildings around the world have downsized their employees, but the comfort parameters in the building had to be kept. The facilities operation rearranged the workstations to keep physical distance and placed plexiglass sheets on the desks for physical protection. A series of measurements have been carried out with workstation set-ups to examine the fresh air rate in the occupied zone. The effect of plexiglass sheets placed on the desks was also examined to see how it changes the airflow pattern in the occupied zone. As the sheets act as a barrier, the primary air does not reach the occupied zone, therefore, the fresh air rate is less. To modify the properties of the ceiling diffusers a new air-ventilation service element was developed. This attachment allows modifying the properties of the ceiling diffusers. Simulations were made at the relevant zones to validate the measurements. Based on design software, the fresh air ratio for a standard ceiling swirl diffuser is 2.46 v% (volume percentage). A numerical model was used to show the fresh air ratio with the system elements for the two different table arrangements, which were 18.3 v% and 21.4 v%, respectively. [ABSTRACT FROM AUTHOR]

It is essential to understand the factors influencing thermal responses to improve human comfort and properly reduce energy consumption. It has been confirmed that parameters unrelated to the thermal environment can influence the thermal responses of occupants. These factors are yet to be investigated and studied in detailed, especially under different environmental conditions because of insufficient knowledge about indoor environment factor interactions. Therefore, accurate and high-quality data of light intensity is highly important to be focused on. Accordingly, the influences of light intensity on the temperature and air velocity of the indoor environment were studied and investigated under natural and controlled environmental conditions. The main objectives are to investigate and evaluate various effects of light intensity parameters on the indoor room temperature and air velocity for the indoor environmental condition. An effect of light intensity and simulation analysis for the indoor environment was performed using the ANSYS platform. The main parameters such as indoor temperature and air velocity were measured. Based on the results obtained from simulation analysis, the halogen lamps possess an enormous influence on the indoor environmental parameters than the LED lamps; the light intensity is directly proportional to the air velocity and indoor temperature. Conclusively, the results of this study can be considered as a reinforcement step in emphasizing the actual effect of lighting intensity, and the required lighting must be in accordance with the daily duty. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The air flow and pollutant concentration fields in a street canyon affected by trees could affect the comfort and health of residents. At present, the description of the non-uniform/discontinuous distribution of leaves is difficult. In this study, the leaf distribution in the canopy was characterized by establishing non-continuous (uniform/random) algorithm based on a numerical simulation method, and the effects of canopy properties including, height, porosity and uniform/random leaf distribution, on the airflow and pollutant concentration fields in urban street canyons were investigated. The position of the tree canopy was found to directly affect the airflow field form and the air velocity distribution in the street canyon at low inflows. The average air velocity in the street canyon could be reduced significantly when the top of the tree canopy is near the top of the street canyon. The air velocity and pollutant concentration in the street canyon would vary only slightly due to the canopy porosity. Due to the increasing canopy porosity, the air velocity would increase, and the pollutant concentration would be reduced. The leaves are non-continuous and uniformly distributed at constant porosity, which does not significantly change the velocity distribution and pollutant concentration in the street canyon. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

In recent years, air circulation has been used in protected cultivation to improve the microenvironment around seedlings, which in turn enhances photosynthesis and seedling growth. However, a practical and precise air circulation device has not yet been reported, especially one for growing seedlings in a greenhouse. Considering the use of a seedbed in seedling cultivation, a blower that can move back and forth on the seedbed and accurately control the air velocity is designed. In this experiment, we take the nonblowing treatment as the control (CK); three air velocities (0.3, 0.6, and 0.9 m/s) were selected to investigate the effect of interval blowing on the microenvironment of the canopy, physiology of seedling growth, stomatal characteristics of leaves, and stem mechanics of tomato seedlings. The three air velocities were found to significantly reduce the canopy temperature by 0.44, 0.78, and 1.48 °C lower than the CK, respectively, and leaf temperature by 0.83, 1.57, and 2.27 °C lower than the CK, respectively, in cultivated seedlings during summer. The relative humidity of the tomato seedling canopy decreased by 2.7% to 7.0%. Compared with the CK, the plant height of tomato seedlings decreased by 13.54% and root dry mass, root-shoot ratio, and seedling quality index (SQI) increased by 34.63%, 21.43%, and 14.29%, respectively, at 0.6 m/s. In addition, mechanical indexes such as hardness and elasticity of the tomato seedling stem were higher under air disturbance than those of the CK. The best effect was seen in the treatment with the air velocity of 0.6 m/s, in which the hardness and elasticity of the stem base and the first node were significantly higher than that of the CK. In conclusion, air disturbance generated by the air blowing device we designed effectively improved the microenvironment around the plants, enhanced the physiological activity of the seedlings, and thereby promoted seedling growth.

The purpose of this study was to design and determine the performance of a dryer for drying corn with biomass burning energy sources. The dryer consists of a biomass stove, a heat exchanger, and a drying cabinet. The dimensions of the biomass stove are 500 x 500 x 800 mm with a diameter and hole distances of the biomass stove wall is 10 mm and 50 mm, respectively. The heat exchanger pipe diameter is 25.5 mm, the drying cabinet 500 x 500 x 600 mm, and the biomass was rice husk. The heat exchanger is made of stainless steel pipes arranged in a parallel arrangement. A heat exchanger pipe connects the biomass stove to the drying cabinet in order to avoid drying products from burning biomass contamination. The results showed that the drying rate could be faster if the air velocity increases. Drying corn in order to reduce water content from 19% to 12% takes 47 minutes with an air velocity of 3 m/s.

The benefits of a good ventilation in classrooms are a well-studied topic regarding health and learning outcomes. However, many studies still show poor results regarding air quality, air change rate and air velocities. In this paper, typical Estonian classroom air distribution solutions were studied in an air distribution laboratory at Tallinn University of Technology. The air change efficiency was measured with CO2 tracer gas concentration decay method. For determining the contaminant removal effectiveness, continuous dose method was used to create a constant contaminant source. In addition, by using air velocity probes, we conducted draught measurements in the mock-up classroom. Tests were conducted using dedicated room-based air handling unit and thermal mannequins for imitating heat sources from students. We found that all solutions studied ensured the air change efficiency roughly corresponding to fully mixing air distribution, but local ventilation effectiveness values of contaminant removal showed large variation from 0.6 to 1.7 stressing the impact of source location. Grouped ceiling supply circular diffusers and single vertical supply grille air distribution commonly used in renovated educational buildings resulted in higher draught risk on the border of the occupied zone. High air velocities recorded in some areas of the classroom perimeter, well explain why draught is considered as one of the main reasons why the airflow rates are reduced, or supply air temperatures are lifted compared to designed values. Perforated duct diffusers resulted in acceptable air velocities. In conclusion, local ventilation effectiveness of contaminant removal showed that fully mixing is not a case with a point source, although air change efficiency determined with equally distributed source showed fully mixing conditions. Therefore, in those cases, the air change rate should be increased to achieve the same ventilation effectiveness. Based on the experiments conducted, a point source ventilation effectiveness measurement method for the breathing zone is proposed. This value determined at least with two source locations can be used in infection risk-based ventilation design.

Improvement of air flow distribution, air velocity and temperature inside a mixed greenhouse dryer was numerically investigated using 3D CFD ANSYS FLUENT code. The study was performed considering six different locations of axial fans inside the greenhouse. Additional elements such as a false ceiling and front and back internal walls were included in some configurations to analyze their contribution in improving the air distribution. Numerical simulations were focused on dynamic fluid models in order to select the best configuration to achieve homogeneous air distribution and velocity among the six proposals. Then, the temperature distribution was analyzed considering the contribution of solar energy in the best-selected greenhouse configuration. Additionally, the Discrete Ordinate (DO) model was used to simulate the mechanism of heat transfer from solar radiation to the greenhouse. The results showed that installing an air recirculation system (including: axial fan, false ceiling, back and front walls), into the greenhouse can increase the air velocity in the drying chamber from 0.71 m/s to 1.5 m/s and the temperature from 315 K to 360 K , which represent an increase of approximately 111.26% y 11.11%, respectively, compared with the greenhouse without an air recirculation system. This improvement could result in the reduction of drying time and a homogeneous moisture content in dry products. • New application air recirculation system was studied. • Differences in fan positioning influence the air flow distribution and air velocity. • The internal walls added to the dryer influence the air flow distribution and air velocity. • The false ceiling and additional internal walls allow to increase the air temperature inside the drying chamber. • The greenhouse drying with the new air recirculation system is suitable for food drying. [ABSTRACT FROM AUTHOR]

Flow field in the enclosed three-dimensional space is very important for the design of the ventilation system. In view of the data processing of the air velocity sensor array composed of multiple sensors, a multi-sensor data fusion algorithm based on the correlation function-Kalman filter algorithm is proposed in this study. Invalid data acquired by flow sensors is excluded by correlation judgement in measuring. Then, the sensor calibration output data and variance are used as the initial estimated value and variance estimation of Kalman filter to perform the multi-sensor data fusion. Compared with the measurement of common sensor calibration, the measurement error of air velocity obtained by this method is smaller. The experimental results show that the method can effectively improve the measurement accuracy, and the experimental results of the three-dimensional flow field measurement based on the data processing method are accurate and reliable [ABSTRACT FROM AUTHOR]