Air Parameter Research Articles

Optimal Design of Air Treatment for an Adsorption Water-Harvesting System

In some areas where access to water is difficult, such as arid regions, it is a feasible measure to acquire water from the air. In this context, a system for water harvesting from the air was designed and manufactured. In order to find the optimal operation parameters of the system, the humidity–enthalpy diagram and the dehumidifier computation software (V2.0, Win7) were adopted for the optimization work. The air treatment process of the system was analyzed and calculated by using the professional software provided by the dehumidifier company. Operation modes of ‘powerful mode’ and ‘economic mode’ were defined in the computation work, which are represented by the water production amount and efficiency (water production per power consumption), respectively. According to computation analysis, the relationships between the main performance indicators and the system design/operation parameters were obtained. By considering the heating power limitation of the system, the wheel dehumidifier rotation speed of 8 rph (revolutions per hour), zonal area ratio of Ap/Ar = 2, and the optimal airflow ratios in different relative humidity (RH) environments, together with the outlet air parameter settings of the surface cooler, were finally defined.

Research on CC-SSBLS Model-Based Air Quality Index Prediction

Establishing reliable and effective prediction models is a major research priority for air quality parameter monitoring and prediction and is utilized extensively in numerous fields. The sample dataset of air quality metrics often established has missing data and outliers because of certain uncontrollable causes. A broad learning system based on a semi-supervised mechanism is built to address some of the dataset’s data-missing issues, hence reducing the air quality model prediction error. Several air parameter sample datasets in the experiment were discovered to have outlier issues, and the anomalous data directly impact the prediction model’s stability and accuracy. Furthermore, the correlation entropy criteria perform better when handling the sample data’s outliers. Therefore, the prediction model in this paper consists of a semi-supervised broad learning system based on the correlation entropy criterion (CC-SSBLS). This technique effectively solves the issue of unstable and inaccurate prediction results due to anomalies in the data by substituting the correlation entropy criterion for the mean square error criterion in the BLS algorithm. Experiments on the CC-SSBLS algorithm and comparative studies with models like Random Forest (RF), Support Vector Regression (V-SVR), BLS, SSBLS, and Categorical and Regression Tree-based Broad Learning System (CART-BLS) were conducted using sample datasets of air parameters in various regions. In this paper, the root mean square error (RMSE) and mean absolute percentage error (MAPE) are used to judge the advantages and disadvantages of the proposed model. Through the experimental analysis, RMSE and MAPE reached 8.68 μg·m−3 and 0.24% in the Nanjing dataset. It is possible to conclude that the CC-SSBLS algorithm has superior stability and prediction accuracy based on the experimental results.

Parametric study and optimization on exhaled particle dispersion in a ward heated by impinging jet ventilation using orthogonal-based grey relational method

During the heating season with high-frequency infection events, an appropriate ventilation method is critical to a healthy hospital environment. In this study, impinging jet ventilation (IJV) was proposed to reduce cross-infection risk in a two-bed ward for winter heating. An Eulerian-Lagrangian approach validated by experimental data was employed to simulate exhaled particle dispersion. Using a full factorial design method, under air changes per hour (ACH) of 6–15 h−1 and supply air temperature (Ts) of 24–30 °C, the effects of supply air parameters on particle dispersion was analyzed. A correlation model was subsequently established to delineate the relationship between supply air parameters and particle elimination. With an orthogonal-based grey relational method, this study compared the contribution and significance of supply air parameters and two uncontrollable factors (i.e., source location and outdoor air temperature), and then optimized the supply air parameters of IJV. The results indicated that the contribution percentage of supply air parameters was higher than 70 % for particle removal and residence time. With an appropriate supply air parameter, the airflow of IJV could comply with human body plume, enhancing removal of fine particles (≤20 μm). However, with a low Ts (lower than 26 °C) or an excessive ACH (more than 12 h−1), the number of fine particles moving upwards might be reduced. To achieve a better performance in preventing cross-infection, ACH and Ts of IJV were recommended to be set at 9 h−1 and 28 °C, respectively. The findings were expected to provide guidance for ward ventilation design.

Application of artificial intelligence in mine ventilation: a brief review.

In recent years, there has been a notable integration of artificial intelligence (AI) technologies into mine ventilation systems. A mine ventilation network presents a complex system with numerous interconnected processes, some of which pose challenges for deterministic simulation methods. The utilization of machine learning techniques and evolutionary algorithms offers a promising avenue to address these complexities, resulting in enhanced monitoring and control of air parameter distribution within the ventilation network. These methods facilitate the timely identification of resistance faults and enable prompt calculation of ventilation parameters during emergency scenarios, such as underground explosions and fires. Furthermore, evolutionary algorithms play a crucial role in the advancement of methods for visual analysis of ventilation systems. However, it is essential to acknowledge that the current utilization of AI technologies in mine ventilation is limited and does not encompass the full spectrum of challenging-to-formalize problems. Promising areas for AI application include analyzing changes in air distribution caused by unaccounted thermal draft and gas pressure, as well as developing novel approaches for calculating shock losses. Moreover, the application of AI technologies in optimizing large-scale mine ventilation networks remains an unresolved issue. Addressing these challenges holds significant potential for enhancing safety and efficiency in mine ventilation systems.

Study on indoor air temperature and moisture behaviour in historical churches

Increased indoor air humidity in cultural heritage buildings in the Baltic States region results in the deterioration of cultural heritage values. Existing norms, standards, and research do not specify the necessary conservational microclimate indoor air parameter limits. Two main types of historical cultural heritage building constructions exist based on enclosing structures – wood and masonry, with various heating strategies and usage intensities. This study complements previous research on the microclimate of Krimulda Church and compiles measurements of three additional Latvian churches: Turaida Church, Riga Jesus Church, and Liepaja St. Trinity Cathedral. Microclimate measurements were conducted in two wood and two masonry churches. Humidity ratio and moisture excess calculations were derived from the measurement data. Results indicate that in certain cases, the moisture excess threshold of 6 g/m3 and indoor air humidity ratio threshold of 15,6 g/kg are exceeded, posing a significant risk of condensation. Moisture evaporation levels from masonry church constructions were identified. The study reveals conservational microclimate indoor air parameter limits for various types of churches in the Baltic States climatic region.

Research Progress of Evaporator Surface Frost Suppression Technology

Frosting of the evaporator leads to the increase of its thermal resistance and the reduction of system COP, which affects the safe use and efficient operation of air source heat pump. This paper summarizes the common evaporator frost suppression methods researched by scholars at home and abroad, and classifies the frost suppression methods into four categories: changing the temperature of the evaporator, changing the temperature of the evaporator, and changing the temperature of the evaporator. This paper summarizes the common evaporator frost suppression methods researched by scholars at home and abroad, and classifies the frost suppression methods into four categories: changing the inlet air parameter of the evaporator, modifying the surface of the evaporator, optimizing the structure and design of the evaporator and applying an external electromagnetic field to the evaporator, and overviews the progress of the research on the four frost suppression methods and makes an outlook to provide references and proposals for the further development of evaporator frost suppression technology of the air source heat pumps.

Constructing year-round energy-efficient fresh air handling unit with exhaust air heat recovery using multi-condition design

Traditional fresh air handling units with exhaust air heat recovery insufficiently utilize exhaust air waste energy, and are designed under the design-load condition, which are unable to efficiently adapt to the varying fresh air conditions for both the energy consumptions of compressors and fans. To promote energy efficiency, a fresh air handling unit with exhaust air heat recovery is constructed in this study by grade matching of loads and waste and natural energies under different typical fresh air parameter conditions, and the improved year-round efficient system configuration is determined by combining the configurations obtained under each typical condition. In addition, numerical models are adopted to calculate the energy and economic performances of the system in an office building in Nanjing, China, and a traditional system is also analyzed for performance comparison. The main conclusions are as follows: 1) The improved system configuration is determined to be a heat-recovery device plus a two-stage heat pump that can operate close to a separately designed configuration under various cases, thereby ensuring efficient operation throughout the year; 2) Compared with a traditional fresh air handling unit for fresh air load treatment with a variable refrigerant flow system in Nanjing, China, the annual saving rate of the proposed system is 14.4 %; 3) Compared with the traditional system, the static payback period is 1.1 years.

Preliminary Study on Indoor Air Temperature and Moisture Behaviour in 13th-Century Churches in Latvia

The microclimate plays a crucial role in the conservation of historical cult buildings and their artifacts for future generations. In order to conserve these buildings and their artifacts, it is imperative to ensure that the microclimate is conserved. The norms and standards existing so far in Latvia do not stipulate thresholds for air parameters that would ensure a conserving microclimate for historical cult buildings. In order to identify these thresholds, the air parameters were measured simultaneously at nine measuring points within the Krimulda Church (LV) of the 13th century. The temperatures of the surfaces of the building envelope and potential condensation were calculated using the actual data of indoor and outside air. The indoor and outdoor air humidity ratio was calculated for each measurement. The conservation threshold of indoor microclimate parameters was determined by using intermittent heating on the basis of the air parameter fluctuations and calculations. The moisture vapours from the building structures were quantified in this research. The indoor humidity ratio during the warm season and the upper threshold during the heating season were determined.

Improvement of Saccharomyces propagation performance through oxygen-enriched air and aeration parameter variation

A variety of yeast applications in the food and beverage industry require individual and reproducible yeast propagation at high yields and consistent quality. One quality-determining parameter for yeast propagation is effective aeration to avoid oxygen depletion. Therefore, this work investigated three important aeration parameters: airflow, pulse time, and oxygen concentration, for their influence on yeast propagation. The aeration of a propagator involves phase transitions which are gradient-driven processes and can be accelerated with higher gradients between the liquid medium and the gas bubbles. In this study, oxygen-enriched air generated with membrane filters was used to aerate the system in an easy and cost-efficient way without the need for expensive technical gas usage. Propagation experiments were carried out in a pilot-scale reactor equipped with a membrane filter system for enhanced oxygen concentrations in ingas and online sensors for representative monitoring of the process. The membrane filter system is based on the separation of nitrogen in compressed air, leading to oxygen enrichment. Using oxygen-enriched air for propagation aeration showed higher oxygen transfer into the medium and the anaerobic process time caused by oxygen depletion due to high cell numbers was reduced by an average of 7.4% for pulsed aeration. Additionally, we conducted experiments with controlled measures of dissolved oxygen using different oxygen concentrations for aeration. The main objective of this study is to present a new and affordable optimization of propagation aeration using membrane filtration to enrich process air. The results showed increased cell counts for higher ingas oxygen concentrations and no negative impact on cell vitality was observed. Hence, our investigations showed that using oxygen-enriched air reduced the frequency of pulsed aeration, thus hindering foam formation, a limiting factor of the yeast propagation process.

Indoor thermal and humid stratification and statistical distribution in ice arenas

On-site measurements in four different ice arenas were carried out under multiple working conditions to study the indoor vertical temperature and humidity distributions. It's indicated that air distribution system has a great impact on the vertical profiles and brings about different inflection points. In order to achieve the same moisture level of around 3 g/kg in the occupied ice field, supply air humidity of jet ventilation should be reduced to 0.4 g/kg while that of ground displacement ventilation could be as high as 3.0 g/kg. The vertical profiles under different air distribution systems are simplified by calculating the air parameter discrepancy brought by dehumidification air supply in the present research. The discrepancy profile was characterized by Gaussian function with three shape coefficients. Based on the measured results, the variation of shape coefficients with different influencing factors was investigated. It is demonstrated that the extreme point coefficient can be estimated by the height of the air outlet, while the scaling range coefficient varied linearly with the relative air supply parameters. This study accumulated considerable measured data to comprehensively understand the current situation of temperature and humidity stratification in ice arenas. The proposed statistical variation distribution contributes to the precise environmental control and the efficient design of ice arenas.

Influence of permeability on rainfall infiltration based on water gas two phase flow

The permeability function is one of the key properties in unsaturated soil mechanics and variation of parameters in soil water characteristic curve can easily affect matric suction as well as infiltration. The purpose of this research is to explore the significant effect of parameters in SWCC on rainfall infiltration. A water gas two phase flow analysis method was conducted to investigate the influence of parameters in SWCC on stable infiltration intensity. Result showed that when saturation was low, stable intensity of infiltration was greatly affected by matric suction because the modified parameters were related to pore size distribution such as air entry value ρ0 and parameter m. When saturation was close to 1, the influence of soil infiltration intensity was almost not affected by matric suction. The minimum value of stable infiltration of intensity was mainly determined by the intrinsic permeability, while saturation of this value was mainly affected by soil water characteristic curve, intrinsic permeability coefficient of soil as well as water relative permeability coefficient.

Soil Water Characteristic Curve Analysis of Weathered Granite Soils with Various Fine Content

Determining the parameters related to unsaturated soil properties considering capillary and adsorption phenomena is challenging. In addition, the matric suction generated in unsaturated soil increases the stability of the slope; however, the decrease in matric suction owing to heavy rain causes a decrease in slope stability. Therefore, it is crucial to determine the parameters of unsaturated soil accurately. In this study, the engineering characteristics in the unsaturated state were analyzed using weathered granite soil, which is typically distributed in mountainous areas in Korea. Four samples were prepared in which the compositions of the fine contents of weathered granite soil were 0%, 10%, 20%, and 30%, and a soil characteristic curve test was performed on the samples. In the coefficient prediction method, the widely applied van Genuchten model was used to analyze the air entry value and parameter values according to the fine content of weathered granite soil in the range of the drying process. As a result, a correlation between the fine content in the weathered granite soil and the air entrainment value and parameter values was identified.

Experimental investigation of frosting process on ice surface in ice rink

Ice rink is a special kind of public building with high energy consumption, in which frost would occur on ice with high humidity ratio. Frost on ice would substantially affect the quality of ice, which needs to be avoided in high level competition. In this paper, the basic process and characteristics of frost formation on ice are obtained by means of experiment. At the same time, the relationship between frosting time and humidity ratio for different stages are discussed. The feasibility of frost thickness growth model is also validated by experiment. Based on the comprehensive consideration of time and grade requirements, the control range of surrounding air humidity ratio could be discussed and expanded. The upper limit of humidity ratio could be extended by 0.5–0.9 g/kg higher than the saturated value corresponding to the ice surface temperature when the target is no obvious condensation droplets on ice for 4 h. The upper limit could be extended by 1.0 g/kg when the target is no obvious frost crystals on the ice for 4 h. This research also reduces the difficulty of humidity control in ice rink with a wider range. It also provides a theoretical basis for reasonable and energy-saving air parameter control requirements in ice rink.

Simplified models for predicting thermal stratification in impinging jet ventilation rooms using multiple regression analysis

Inappropriate thermal stratification characteristics can degrade the ventilation performance of impinging jet ventilation (IJV). In the present study, an analysis method using dimensionless parameters is proposed for predicting the thermal stratification, and the Box-Behnken design method is employed to determine the simulation cases of influencing factors for thermal stratification. The thermal performance in IJV cooling room is investigated by computational fluid dynamics (ANSYS Fluent), and the effects of supply air parameters, inlet area (S*) and height (h*) on thermal stratification are discussed, respectively. A further supply air parameter is represented by the thermal length scale (Lm), which is applied to evaluate the combined effect of inertial force and thermal buoyancy on supply airflow. The results show that the driving force on supply airflow changes from buoyancy dominated to inertial dominated with increasing Lm, leading to the thermal stratification profiles changing from thermal stratification to uniform distribution. For small Lm, the thermal stratification profiles are similar for different inlet areas, while the dimensionless air temperature decreases with increasing inlet area. However, the larger inlet area promotes a more uniform temperature distribution for large Lm. In addition, the thermal stratification profiles are similar regardless of the inlet height for both small and large Lm conditions, indicating that the dimensionless air temperature is a weak function of inlet height. Finally, multiple regression models related to Lm, S* and h* are developed for predicting the thermal stratification, which can provide a reference basis for the determination of temperature distribution in IJV cooling rooms.

Whirlwind Classification with Imbalanced Upper Air Data Handling using SMOTE Algorithm and SVM Classifier

Whirlwind is a natural disaster that often occurs and is difficult to predict from some time before. Early identification is needed to prevent a lot of casualties and losses. Whirlwind caused by instability in the atmosphere. Instability in the atmosphere usually occurs at the beginning of the day and the whirlwind can be identified based on the upper air parameter which can represent atmospheric instability. The purpose of this research is to optimize SVM classification with SMOTE algorithm to handling problems in imbalanced data and this research can minimize casualties and losses or also be a breakthrough for disaster-prone areas to be given early warning. The process for identifying whirlwind has several stages, namely pre-processing, imbalanced data handling, and classification. Pre-processing is normalized data. Whirlwind data has a classification problem, namely inter-class data that is not balanced so it needs to be corrected using the SMOTE Algorithm. Research on the identification of whirlwind using a combination of SMOTE-SVM produces the best accuracy is 98.8 %. When compared to data without the SMOTE algorithm the results obtained are better if the SMOTE method is applied. The specificity value is also better when given the SMOTE method. Based on these results it can be concluded that SMOTE can overcome the problem of imbalanced data in the upper air data by increasing the value of the classification of the whirlwind.

Hydrothermal performance of the external wooded frame wall structure reinforced with ballistic panels

In recent years construction of bullet resistant walls has become very common not only for military buildings but also for public and residential buildings. The existing wall structure in those buildings is reinforced by ballistic panels. However, in the cold climate regions external application or installation of the ballistic panels can cause interstitial water vapor condensation. Also, an incorrect application of such panel on the internal surface can lead to an insufficient drying of the structure during the summertime. This paper presents an analysis of thermodynamic properties of ballistic panels. For this purpose, laminated and non-laminated ballistic panels were examined. Thermal conductivity features such as water vapor permeability were evaluated in laboratory conditions. Based on gathered results the DELPHIN simulation software and THERM calculation tools were used to analyze the thermal resistance of wooded frame wall reinforced with ballistic panels. The obtained results were validated under controlled environment. Temperature and moisture measurements were performed inside the tested wooded frame structures reinforced by ballistic panels under different internal and external air parameter fluctuations.

Small-angle measurement in laser autocollimation based on a common-path compensation method

ABSTRACTIn this study, a common-path compensation method is proposed for the laser beam drift resulting from the air parameters to enhance the stability of small-angle measurement in laser autocollimation. The measuring and reference beams generated with this method can propagate along approximately the same route such that the drifts in the two beams are nearly equal. Therefore, the angular drift of the measuring beam can be adequately compensated by that of the reference beam. The compensation principle was analyzed, and the experimental results revealed that, with three types of air parameter disturbances, the static measurement stability was better than 0.193 arcsec in 100 min after compensation, and the compensation rate was higher than 86.6%. Additionally, the dynamic measurement stability was 0.227 arcsec in 50 s after compensation, and the compensation rate was 53.6%. It is confirmed that the proposed method is effective for laser autocollimation.

IoT - Based Wireless Sensors for Agriculture Monitoring

The Internet of Things (IoT) is designed for the purpose of multi-hop transmission, collision-free transmission, and high energy efficiency in automated environments by the use of sensor nodes. Today the world deals with major problem in agriculture. The ongoing changes in atmosphere have expanded the significance of agriculture observing, making it a topical and very dynamic research region. This field depends on remote detecting and on remote sensor systems for social occasion information about the farming and post to client through IoT This information is can be refresh often to the cloud and client can screen soil dampness, Temperature, air parameter sensor like humidity. The correspondence of two agribusiness grounds can be imparted utilizing RF handset with 8 channel, 2Ghz specification. In this paper, we briefly study about wireless sensor network and internet of things and its protocols. The detail description of wireless sensor network includes its architecture, applications, etc. The internet of things has been defined architecture and protocols with its related applications. With the help of internet, the sensor can pass its collected information to the users.

Construction and Algorithms of the Onboard System for Measuring the Helicopter Air Data and State of the Atmosphere with a Stationary Receiver, Ion-Mark and Aerometric Measurement Channels

The problem is considered of measuring the air parameters and state of the atmosphere on board the helicopter under the aerodynamic disturbances of the main rotor vortex column. The functional scheme, design features of the air parameter sensor and algorithms of information processing at the parking, starting, takeoff and landing and other modes of helicopter of the onboard system with a fixed receiver, ion-mark and aerometric measurement channels are revealed.

Mathematical modelling of the indoor ice arena with two control volumes for calculation of the air exchange

The existing methods of calculation of ventilation and air conditioning systems in the indoor ice skating arenas specify the audience stand area zone separately of the ice rink space. They do not take into account interaction of the zones, which have different temperature and moisture parameters. Calculation of the required air exchange of the ice field area is represented herein through mathematical modelling, which reasonably divide the space volume in two distinctive control areas. A mathematical model of the physical process, which takes place in the indoor ice arena space, enables determination of the air exchange to get the required normative parameters of the air in separate space KOs. The suggested method proposes a procedure of the microclimate parameter calculation of separate control volumes of the indoor ice arena space, when the air is distributed according to an “up-to-down” scheme. It will permit to determine the parameters and the operation modes of supply and exhaust ventilation equipment. The method takes into account the processes of heat- and mass transfers in two distinctive control volumes of the ventilated area under permanent conditions. Methodical bases are developed for physically reasonable way of calculating the required air exchange, bearing maximal consideration of the factors influencing heat-air processes in the ventilated volume as a whole and according to two separate typical control volumes of the indoor ice arena ventilated space. The dependence of changes of the relative air consumption in an axis-symmetric jet from the sectional area of the hole, the height of location and the dynamic coefficient of the diffuser are given herein. The method allows determination of the location height and the type of the air diffuser, as well as the air parameters at the jet outlet from the diffuser to provide the design air parameters at the jet inlet into the skating-rink area. There are presented the air jet temperature changes at the jet inlet in the serviced area, as well as the air jet temperature changes at the outlet of the diffuser depending on the amount of the inflow air and the location height of the diffusers. The submitted I-d diagram shows the changes of the air inflow jet settings in the indoor skating-rink space with two control volumes, when the air exchange is made according to the “top-to-down” scheme. The graph-analytical method of the air parameter calculations in the skating-rink area on the basis of I-d-chart, allows to consider the process of mixing air of two control volumes and to clarify the air parameters at the diffuser jet outlet, taking into account the type of the jet, the height of the diffuser location and the characteristics of the diffuser. If the air exchange of the ice rank zone is performed according to the “top-to-down” scheme, the availability of heat and humidity emissions in II KO (stands zone) makes reasonable provision of the inflow air supply by the smallest possible number of the air diffusers, as well as determination of the height of the air diffuser location closer to the served area of the ice rink.