Humidity Distribution Research Articles

Online Monitoring of the Temperature and Relative Humidity of Recycled Bedding for Dairy Cows on Dairy Farms

In large-scale dairy farming, the use of high-temperature-fermented dairy manure bedding instead of rice husk-based bedding and other commercial types of bedding is widely favored. Strip-stacking aerobic fermentation is the main production method of dairy manure bedding, but it has problems including unstable fermentation and the secondary breeding of pathogens. In this work, a multi-probe, integrated, online monitoring system for temperature and relative humidity was used for fermentation process optimization. The effects of the temporal and spatial distribution of fermentation temperature and relative humidity on the nutrient content curve and the moisture and ash content of manure bedding materials were systematically studied. The effect of the fermentation process on the retention rate of effective bedding materials (cellulose, hemicellulose, and lignin) was analyzed. The experiments proved that high-quality bedding material can be obtained through reasonable stacking fermentation. The fabricated bedding material has a total dry base content consisting of cellulose, hemicellulose, and lignin of 78%, an ash content of 6%, and a nutrient content of 17%. The obtained bedding material was produced to increase the bed rest rate and continuously inhibit the bedding bacteria content, keeping it at a low level for 5 days. This study proves that temperature and humidity monitoring can guide the optimization of the strip-stacking fermentation process of dairy manure and that it can be applied to large-scale farms to improve fermentation parameters.

Spatial Distributions of AQI, PM2.5, Relative Humidity, Speed, and Temperature in Twenty-Two Towns in Nigeria

Spatial Distributions of AQI, PM2.5, Relative Humidity, Speed, and Temperature in Twenty-Two Towns in Nigeria

Redistribution of Hydrothermal Resources on Different Elements of the Microrelief of Soils in the Semi-desert Zone and Agrolandscapes under Wheat

In the semi-desert regions of Azerbaijan there are habitats with varying elevations of only a few tens of centimeters. The zonal soils on the territory of the massif are gray-brown soils. Gray-brown soils develop under ephemeral plant cover. The soil is carbonate throughout the entire profile. Below the carbonate horizon lies a layer enriched with sulfates in the form of veins of crystalline gypsum. The content of absorbed sodium in the gray-brown soils of the deluvial plain of the Siyazan-Sumgait massif is 30-50% of the number of absorbed bases in the Solonetz-Columnar soil horizon. The amount of humus in the upper layers of the soil fluctuates between 1-2%, towards the bottom it sharply decreases. In studies carried out on gray-brown soils of the Siyazan-Sumgait massif, hydrothermal potential indicators vary within the range of 426-552 m3/ha. The distribution of temperature and humidity in depth in the soil under wheat differs from the natural habitat. In the arable layer, the temperature is evenly distributed throughout the entire profile, while the humidity gradually increases in the lower layers. The influence of the hydrothermal regime on wheat yield was: 2022 — 24.0-30.0 cwt/ha; 2023 — 16.0-24.5 cwt/ha.

Computational analysis of nasal airflow and its alteration by a nasal dilator

Nasal airflow obstruction correlates with several ailments, such as higher patency, increased friction at the mucosal wall or the so-called Little's area, improper air conditioning, and snoring. Nasal dilators are frequently employed, mainly due to their ease of access and use, combined with their non-permanent and non-surgical nature. Their overall efficacy, however, has not been clearly demonstrated so far, with some studies reporting conflicting outcomes, mainly because being based on subjective evaluations. This study employs Computational Fluid Dynamics simulations to analyze the flow inside a real nose, performs an objective assessment of a nasal dilator's effect in terms of airflow and air conditioning, reporting flow paths, friction levels, heat and water fluxes and detailed temperature and humidity distributions. Coincidentally, the studied nose presents a septal deviation, with one nostril being wider than the other. The tubes of the dilator used in both nostrils are identical, as with any standard commercial dilator. Consequently, the dilator widens one nostril, as intended, but results in an obstruction in the other. This allows simultaneously addressing two situations, the nominal function of the dilator, as well as an off-design case. Results indicate a 24 % increase in nasal patency in the design situation. The effect, however, is limited, as quantified by appropriate measures, such as the flow-generated friction at the nose surfaces and the temperature fluxes. Hence, the effect of such a dilator in nominal conditions is perhaps not as large as might be hoped. In the off-design situation, nasal resistance increases by 62 %, an undesirable effect, illustrating the consequences of using an inappropriate dilator.

Coupled system for underground heating exchange and solar heat-humidity regulation in greenhouse: Experimental study and simulation analysis

In winter, greenhouses located in mid to high latitudes are required a function of dehumidification and warming due to the low outdoor temperature. Focusing on small spires greenhouses, this study regulates the low temperature and high humidity environment inside the greenhouse and proposes a new-type of greenhouse heat and humidity regulation system by combining composite solid desiccant dehumidification with ground heat exchange system. The greenhouse internal environment is warmed and dehumidified at night by utilizing the adsorption effect of the compound dehumidifier and the sensible heat exchange between the heat exchange system in the ground and the greenhouse. Solar thermal energy is collected during the day using multi-curved tank collector (MTC) for thermal storage in the geothermal system and desiccant desorption. The rationality of pipeline layout is verified through CFD simulation, and the indoor temperature and humidity distribution during the system operation is explored. The experimental results show that the moisture adsorption capacity of the composite desiccant SG-CaCl2 for 10h is 0.511 g/g. The optimal regeneration temperature is 80–100 °C. This system can reduce the nighttime relative humidity of the greenhouse in winter from 96.5 % to 83.6 %, and the average indoor air temperature after warming is 12.8 °C. The heat exchange efficiency of the underground heating exchange system is 0.38. During the desorption phase on daytime, the maximum outlet temperature of MTC is 103.8 °C, and the average heat collection efficiency is 0.42. The system can effectively regulate the air environment in the greenhouse to the appropriate zone for crop growth by combining solar thermal collector technology with recyclable solid dehumidification technology.

Variability in the properties of the distribution of the relative humidity with respect to ice: implications for contrail formation

Abstract. Relative humidity with respect to ice (RHi) is a key variable in the formation of cirrus clouds and contrails. We document its probability density function (PDF) using long-term Measurements of Ozone, Water Vapour, Carbon Monoxide and Nitrogen Oxides by In-Service Airbus Aircraft (MOZAIC) and the In-service Aircraft for a Global Observing System (IAGOS) observations over the period 1995–2022 in the upper troposphere (UT) and the lower stratosphere (LS) between 325 and 175 hPa. The characteristics of the RHi PDF differ in the UT and in the LS of the high-latitude regions (HLs) and mid-latitude regions (MLs) of the Northern Hemisphere. In the LS, this PDF decreases exponentially with increasing RHi. In the UT, it first increases exponentially in subsaturated conditions and then decreases exponentially in supersaturated conditions. Because of these different behaviors, the PDF for the combined UT and LS is bimodal. In contrast to the HLs and the MLs, the RHi PDF in the tropical troposphere decreases exponentially with increasing RHi. The different forms of PDF, in the tropics and in the higher-latitude regions, lead to a global PDF of RHi in subsaturated tropospheric conditions that is almost uniform. These findings invite caution when using MOZAIC and IAGOS measurements to calibrate large-scale simulations of RHi. The variability in RHi properties associated with that of temperature also has implications for the formation of contrails. We examined the impact of switching fuel (from kerosene to bioethanol or liquid hydrogen) on the frequency of contrail formation using the Schmidt–Appleman criterion. We show that bioethanol and, to a larger extent, liquid hydrogen would produce more contrails. The impact of a potential change from kerosene to these alternative fuels decreases with decreasing pressure but increases when moving from the higher latitudes of the Northern Hemisphere to the tropics. Finally, we emphasize that investigations of the impact on contrail occurrence frequency as a result of switching from fossil kerosene to more sustainable fuels must be carried out in various meteorological conditions.

Membrane role in heat and mass transfer resistance distribution and performance of hollow fiber membrane contactor for SGMD desalination

Hollow fiber membrane contactor (HFMC) is the core device of heat mass exchange between seawater solution and sweeping air in sweeping gas membrane distillation (SGMD) desalination. In order to reveal the distribution of heat and mass transfer resistance on feed solution side, porous membrane side and sweeping air side, a mathematical model considering the simultaneous heat mass transfer and water vapor diffusion mechanism in the membrane pores was established for the cross-flow HFMC. The simulation results of the model were compared with experimental results and literature results. Comparison shows that the deviation of simulation results of the model is less than 13.4 %, which verifies the accuracy and reliability of the simulation results. Influences of the main structural characteristics of porous membrane on the resistance distribution of heat and mass transfer, efficiency and membrane flux were explored. Air side dominates the heat transfer process, while the membrane side accounts for less than 39 % of the total heat transfer resistance for the main range of membrane microstructure parameters investigated. The mass transfer is controlled by the porous membrane except for thin membrane with a thickness of less than 100 μm. Membranes with porosity above 0.8 and as thin as possible can achieve better mass transfer efficiency and freshwater flux. Increasing mean pore diameter has a strong promotion effect on the increase of membrane flux before it reaches 150 nm, and beyond this critical value, the water vapor diffusion mechanism changes from Knudsen collision to molecular collision. Effects of different operating parameters and membrane microstructure parameters on air temperature distribution and humidity distribution were also analyzed.

STUDY OF THE EFFICIENCY OF THE FUNCTIONING PROCESS OF THE MECHATRONIC SYSTEM OF ENSURING THE MICROCLIMATE OF ANIMAL PREMISES

The development of the livestock industry is the basis of Ukraine's food security. One of the ways to solve this problem is to improve the conditions of keeping animals, including improving the microclimate of livestock and poultry premises. Modern animal husbandry technologies make high demands on the microclimate in livestock premises. According to scientists, animal husbandry specialists and technologists, animal productivity is determined by 50...60% feed, 15...20% by care, and 10...30% by the microclimate in the livestock premises. Deviation of the microclimate parameters from the established optimal limits leads to a decrease in milk yield by 10...20%, an increase in live weight – by 20...35%, an increase in the departure of young animals to 5...40%, and a decrease in laying hens – by 30%...35%, costs of an additional amount of feed, shortening the service life of equipment, machines and the buildings themselves, reducing the resistance of animals to diseases, negatively affecting the service personnel. The article presents a structural and technological scheme of a mechatronic system for ensuring a normative microclimate of livestock premises, which allows to increase the efficiency of ensuring a normative microclimate of livestock premises by using a mechatronic system for controlling the process of air disinfection using ultraviolet radiation of bactericidal lamps. According to the results of numerical modeling of the air heat exchanger of the indirect-evaporative type, the distribution of the temperature field, vector field of velocities and absolute air humidity in channels of different shapes (square, equilateral triangle, circle) was established. The calculated coefficient of thermal efficiency of the heat exchanger with triangular shaped channels is the whitest in contrast to square and round shapes. A comparative analysis of humidity distribution in channels of different shapes confirms that the absolute humidity of the thermal air flow decreases earlier in the indirect-evaporative type heat exchanger with triangular channels.

Enhancing Mini Greenhouse Design: A CFD Analysis of Temperature, Humidity, and Wind Flow Distribution

Enhancing Mini Greenhouse Design: A CFD Analysis of Temperature, Humidity, and Wind Flow Distribution

Experimental study of ambient temperature and humidity distribution in large multi-span greenhouse based on different crop heights and ventilation conditions

Analyzing the distribution of temperature and humidity within a greenhouse is essential for optimizing ventilation strategies and improving crop quality and yield. The temperature and humidity distribution of eight-span greenhouse under natural ventilation and mechanical ventilation is studied experimentally. The influence of different crop height on temperature and humidity distribution in greenhouse and the influence of different mechanical ventilation strategies on temperature regulation were discussed. The results showed that the temperature difference between inside and outside the greenhouse decreased with the increase of crop height. Under natural ventilation conditions, the soil surface temperature is the highest, and the temperature at 0.5 m above the surface is the lowest, with the maximum temperature difference of 0.9 ℃. The temperature in the greenhouse was higher in the west and lower in the east, and the temperature difference decreased with the increase of crop height. In the east–west direction, the maximum temperature difference between tall crops, short crops and non-planted crops was 0.7 ℃, 0.9 ℃ and 1.0 ℃, respectively. High crops increase the relative humidity in the greenhouse and increase the uneven distribution of relative humidity. When growing tall crops, the difference between indoor and outdoor relative humidity is only 2.3 %. When the external shade and fan are turned on at the same time, the cooling effect is the best, the energy consumption is lower, and the temperature distribution is the most uniform. The results provide a valuable reference for optimizing greenhouse structure, formulating ventilation strategy and reducing agricultural energy consumption.

Modelling Heat and Mass Transfer in High-Capacity Natural Convection Solar Dryers

Predicting solar dryer performance under different environmental conditions or assessing their performance to dry different grains is challenging since repeatable full-scale tests are expensive and time consuming. In the present study, computational fluid dynamics approach was used to model the drying of maize in high-capacity dryers such as greenhouse and solar bubble dryer. The absorption of short-wave radiation and the greenhouse effect in the dryer with incident solar radiation was modelled using a dual-band spectrum. The distribution of airflow, temperature, and absolute humidity was analysed in this study to optimise the drying process of maize. Additionally, these results were also used to quantify the drying rate of both greenhouse and solar bubble dryer. The greenhouse dryer model overpredicted the dryer temperatures by an average of 0.12%, and overpredicted absolute humidity by 0.38 per cent. The average Root-Mean-Square Error (RMSE) of temperature prediction was 1.8 °C, and the average RMSE for absolute humidity was 0.0042 for the greenhouse model. On the other hand, the solar bubble dryer model underpredicted temperatures by 1.7%, and underpredicted humidity values by 0.3 per cent. The mean absolute percentage error for the temperature and absolute humidity prediction of the solar bubble dryer model was 1.69% and 0.28%, respectively. The predicted and observed spatial variation in the temperature was similar for both dryers.

Improvement in Forecasting Short-Term Tropical Cyclone Intensity Change and Their Rapid Intensification Using Deep Learning

Abstract Forecasting the intensity of a tropical cyclone (TC) remains challenging, particularly when it undergoes rapid changes in intensity. This study aims to develop a convolutional neural network (CNN) for 24-h forecasts of the TC intensity changes and their rapid intensifications over the western Pacific. The CNN model, the DeepTC, is trained using a unique loss function, an amplitude focal loss, to better capture large intensity changes, such as those during rapid intensification (RI) events. We showed that the DeepTC outperforms operational forecasts, with a lower mean absolute error (8.9%–10.2%) and a higher coefficient of determination (31.7%–35%). In addition, the DeepTC exhibits a substantially better skill at capturing RI events than operational forecasts. To understand the superior performance of the DeepTC in RI forecasts, we conduct an occlusion sensitivity analysis to quantify the relative importance of each predictor. Results revealed that scalar quantities such as latitude, previous intensity change, initial intensity, and vertical wind shear play critical roles in successful RI prediction. Additionally, the DeepTC utilizes the three-dimensional distribution of relative humidity to distinguish RI cases from non-RI cases, with higher dry–moist moisture gradients in the mid-to-low troposphere and steeper radial moisture gradients in the upper troposphere showed during RI events. These relationships between the identified key variables and intensity change were successfully simulated by the DeepTC, implying that the relationship is physically reasonable. Our study demonstrates that the DeepTC can be a powerful tool for improving RI understanding and enhancing the reliability of TC intensity forecasts.

Spatial distribution characteristics in segmented PEM fuel cells: Three-dimensional full-morphology simulation

Segmented proton exchange membrane (PEM) fuel cells are widely implemented in measuring their internal spatially distributed variables (e.g. current density and temperature). However, the difference between the segmented and ordinary fuel cells in spatial distribution characteristics has not been fully understood. In this work, we studied the spatial distribution characteristics in segmented fuel cells (cell area: 366.6 cm2) utilizing a three-dimensional (3D) large-scale fuel cell model that considers the full morphologies of metallic bipolar plates (BPs) and dot-matrix hydrogen, air and coolant flow distribution zones, including the current density, temperature, water content, etc., and compared with those in ordinary fuel cells. It is found that placing a segmented print circuit board (PCB) next to the bipolar plate (BP) component has little influence on fuel cell performance and internal distribution characteristics, whereas the measured current density distribution in the PCB still has inconsistency with that in the ordinary fuel cell, indicating that the influence of segmentation on electron conduction cannot be neglected. In the fuel cell with segmented BP and PCB, the fuel cell performance decreases significantly mainly due to increased electrical and ionic ohmic loss. In addition, the BP's segmentation significantly influences on the water and thermal state inside the whole fuel cell, leading to inconsistency in the measured temperature, relative humidity (RH) and current density distributions with ordinary fuel cells.

The moist halo region around shallow cumulus clouds in large eddy simulations

AbstractIn this study, the moist buffering halo region of shallow maritime cumulus clouds is systematically investigated using large eddy simulations with various grid resolutions and numerical choices. Autocorrelation analyses of cloud liquid water and relative humidity suggest a converged size of 200–300 m for moist patches outside clouds when the model resolution is below 50 m, but may overestimate this size due to noncloudy moist regions. Based on a composite analysis, the structure of the moist halo immediately outside individual clouds is examined. It is found that, regardless of model resolution, the distribution of relative humidity in the halo region does not depend on cloud size, but on the real distance away from the cloud boundary, indicating some size‐independent length scales are responsible for the halo formation. The relative humidity decays with distance more quickly with finer horizontal resolution, which is possibly related to the model resolution dependence of the cloud spectrum. The halo size near the cloud base is larger than that within the cloud layer and this feature is robust across all simulations. Further analyses of backward and forward Lagrangian trajectories originating from the moist halo region reveal the possible role for subcloud coherent structures in cloud‐base halo formation. Possible mechanisms explaining cloud halo sizes and associated length scales are discussed.

Analysis of microclimate temperature and relative humidity distribution of local poultry house in a subtropical area of Nigeria

The design of the ventilation system to ensure microclimate condition are optimum in poultry houses in the Nigerian context requires knowledge of the microclimate parameter distribution, which is lacking in the literature. This study investigated the patterns of temperature and RH distributions in a typical local poultry house. The specific objectives were to (i) analyse the vertical and horizontal distributions of the microclimate parameters in battery cage poultry housing and deep litter poultry housing, (ii) identify whether the distribution is homogenous or heterogeneous, and (iii) identify the data spread of parameters. An experimental intensive naturally ventilated local poultry house was used for this study. It consisted of deep litter (DL) and battery cage (BC) poultry housing systems partitioned by an air wall. Daytime, nighttime, rainy, and dry season temperature and RH distributions in the BC and DL poultry housing were analysed. Approximately 1.2 °C temperature difference was recorded between the poultry house and the ambient environment during the day and night. The temperature and RH distributions in the poultry housing were heterogeneous. Approximately 5% and 67%–73% of the daytime and nighttime temperature data, respectively, and 37%–41% of daytime RH fell within the optimum values.

Spatiotemporal variability of evapotranspiration in Alpine grasslands and its biotic and abiotic drivers

AbstractTo gain a deeper understanding of the water balances of Alpine grassland ecosystems, it is crucial to know the abiotic and biotic drivers of evapotranspiration. The abiotic drivers are very heterogeneous in mountain regions because elevation, slope and aspect control incoming Rs, and atmospheric layering affect air temperature, humidity and wind distribution. In a study with 24 lysimeter plots distributed over a study area of approx. 300 km2 in the Eastern Alps, we covered a wide range of topographic conditions. We investigated the effects of abiotic drivers on evapotranspiration by measuring evaporation from a free‐water body (Ew). For the biological modulation of crop evapotranspiration (ETc), we analysed two different grassland types (at peak biomass and at low biomass) and calculated the respective crop coefficients (Kc). Results showed that primarily physical drivers such as the accumulated solar radiation from sunrise to measurement (Rs_acc), followed by atmospheric pressure (P), wind speed (u) and vapour pressure deficit (VPD) influence both Ew and ETc. Moreover, ETc is also significantly influenced by standing biomass and the grassland type (i.e., resource use strategies of the vegetation types) and by the geographic location along the valley (i.e., entrance, middle and head of the valley). We suppose plant stress and/or ground winds to be the underlying factor for the significance of the geographic location, yet further research is needed. The current study helps towards a better understanding of the water balance in alpine grassland ecosystems, but we also show that some spatial drivers cannot yet be adequately addressed.

A Control-Oriented Model for Predicting Variations in Membrane Water Content of an Open-Cathode Proton Exchange Membrane Fuel Cell

Proton exchange membrane (PEM) fuel cells have emerged as a viable alternative energy production source for stationary and transportation applications. Reliable and sustainable fuel cell operation requires effective water management. Membrane water content can vary along the stack during transients which can lead to losses in fuel cell performance. To control these variations, a model that predicts the internal humidity dynamics of the stack is needed. In this study, a control-oriented model for predicting membrane water content variation was developed and implemented in MATLAB/Simulink. A lumped parameter model was initially developed and then further discretized into smaller control volumes to track humidity distribution along the stack. To validate the model’s predictions, the predicted results were compared to computer simulation results from GT-Suite. The root mean square error (RMSE) between the model’s prediction and GT-Suite’s simulation results was found to be within 1.5 membrane water content for all cases, demonstrating the model’s capability to capture the variation in membrane water content along the stack. The developed model will be useful for real-time control of membrane water content distribution in PEM fuel cells.

Modeling Environmental Conditions in Poultry Production: Computational Fluid Dynamics Approach

In recent years, computational fluid dynamics (CFD) has become increasingly important and has proven to be an effective method for assessing environmental conditions in poultry houses. CFD offers simplicity, efficiency, and rapidity in assessing and optimizing poultry house environments, thereby fueling greater interest in its application. This article aims to facilitate researchers in their search for relevant CFD studies in poultry housing environmental conditions by providing an in-depth review of the latest advancements in this field. It has been found that CFD has been widely employed to study and analyze various aspects of poultry house ventilation and air quality under the following five main headings: inlet and fan configuration, ventilation system design, air temperature–humidity distribution, airflow distribution, and particle matter and gas emission. The most commonly used turbulence models in poultry buildings are the standard k-ε, renormalization group (RNG) k-ε, and realizable k-ε models. Additionally, this article presents key solutions with a summary and visualization of fundamental approaches employed in addressing path planning problems within the CFD process. Furthermore, potential challenges, such as data acquisition, validation, computational resource requirements, meshing, and the selection of a proper turbulence model, are discussed, and avenues for future research (the integration of machine learning, building information modeling, and feedback control systems with CFD) are explored.

Experimental and computational validation of thermal performance of an active greenhouse solar dryer in no-load conditions

Abstract This study focused on developing a finite element (FE) model using COMSOL Multiphysics to simulate the active mode of a greenhouse dryer under no-load conditions in Ranchi humid subtropical climate. The model visualized the temperature and humidity distribution within the dryer and was validated against real-world experimental results. Under unloaded conditions, the performance assessment revealed a 29.14% efficiency for the proposed dryer and a maximum overall convective heat transfer coefficient of 5.0 W/m2 °C. The internal temperature ranged from 50°C to 70°C, while the relative humidity hovered between 30% and 45%. The COMSOL Multiphysics-based FE model demonstrated close agreement between experimental and predicted results, with minimal statistical error. Overall, the findings suggest that the active mode of the greenhouse dryer could be a valuable tool for crop drying in humid subtropical climates. Additionally, the FE model presents a promising approach for future research and development.

Arbuscular mycorrhizal and ectomycorrhizal plants together shape seedling diversity in a subtropical forest

IntroductionBurgeoning mycorrhizal research has focused on identifying the various diverse mycorrhizal strategies of forest communities. Mounting evidence suggests that mycorrhizae play important roles in regulating forest community structure and composition. However, research into the manifestation of this influence in the seedling stage is lacking, especially in small-scale plots.MethodsOur research utilized structural equation models parameterized using data from a subtropical monsoon broad-leaved evergreen forest situated in Yunnan Province, China.ResultsWe noted that seedlings included plants that utilized both arbuscular mycorrhizal (AM) and ectomycorrhizal (EM) fungi. More seedling plots with the relatively higher species diversity were the product of the mixed mycorrhizal strategy, meaning the coexistence of AM and EM seedlings in a small-scale plot rather than the dominance of one type of strategies. These mixed communities were primarily found on slopes and mountain ridges. The abundance of AM or EM trees indirectly affected seedling diversity by influencing the abundance of different mycorrhizal seedlings. In this case, the diversity of the mixed mycorrhizal community was also restricted by the level of leaf thickness in the community, followed by abiotic factors such as elevation, convexity, soil pH and soil available phosphorus.DiscussionThe effect of leaf thickness on mycorrhizal seedling abundance reflected the importance of water conditions in shaping seedling communities. The effect of convexity on seedling diversity also reflected the limitation of seedling communities by the distribution of humidity and heat conditions during topographic change. The results suggested that it is crucial to preserve seedling diversity via the mixed mycorrhizal strategy of communities in the subtropical forest.