Air Parameters Research Articles

Indoor air quality assessment in the apartment – case study

The application of demand-controlled ventilation is one of the ways, how to reduce energy consumption in residential buildings. The main producer of pollutants in these types of buildings is human being and its activities. The most common measurable air parameters that can be characterized the level of air degradation in rooms are the concentration of carbon dioxide (CO2), air temperature and relative humidity. The aim of our research was to monitor and evaluate these air parameters in real conditions of apartment usage. As part of the research, the experimental measurements were carried out in a selected apartment, where the concentration of carbon dioxide CO2, air temperature and relative humidity were monitored in individual rooms. During evaluating the monitored air parameters, their maximum and minimum values were evaluated. The achieved research results can be applied in computer simulation the operation of a ventilation system in the apartment in order to increase the energy efficiency of the HVAC system while maintaining the required indoor air quality that is necessary for healthy living.

Verification of the Fanger model with field experimental data

Thermal comfort is one of the main aspect of human life due to the period of time each of us spends inside of the enclosed room on one hand as well as the health issues connected with the sick building syndrome on the other. Presently, the international standards are based on the Fanger model with calculations of proper indexes according to the inside air parameters as well as characteristics for room users. The paper presents the verification of Fanger model with experimental data obtained from research conducted in 6 classrooms of an intelligent, educational building. The measurements were acquired by means of Testo 400 meter where air parameters such as temperature or humidity were collected. For other evidence the questionnaire was prepared, where respondents presented their thermal sensation together with the information of their clothes present thermal insulation. The results proved that the Fanger model is not precise, since the findings calculated with the international standard differ from those obtained from the questionnaires.

Analysis of thermal comfort on planes

Thermal comfort of passengers and cabin crew is an important element to be ensured during short and long distance flights. The analysis of this phenomenon is usually conducted based on the measurements of physical parameters of the inside air and factors such as metabolic rate and thermal insulation of clothes. The paper provides an insight into this phenomenon through the literature review on the subject. It presents the assessment of thermal comfort conditions onboard the planes. An important element is the discussion of the current model of thermal comfort proposed by O. Fanger and its usability for the application in planes.

Analysis of indoor environment perceptions in the smart building

Thermal comfort is of fundamental importance for people staying in a closed environment. The article focuses on research on thermal comfort in a smart building. The study was performed using two methods. The first method with the Testo 400 microclimate meter, the second method with anonymous questionnaires. The microclimate meter made it possible to measure air parameters (including temperature, humidity, speed, CO2 concentration). The anonymous poll included questions about the thermal sensations vote, thermal preferences, thermal acceptability vote, air humidity and humidity preferences vote. Students from Poland, faculty of Environmental, Geomatic and Energy Engineering, participated in the study. The research showed that the respondents preferred lower thermal conditions with the temperature range from 22.4 °C to 25.1 °C. The percentage of the students who found the conditions as unsatisfactory - has exceeded the permitted 10% range.

Experimental Investigations on the Performance of a Hollow Fiber Membrane Evaporative Cooler (HFMEC) in Hot-Dry Regions.

The applicability of a hollow fiber membrane evaporative cooler in hot–dry regions was investigated by experimental studies. To better understand the actual operating environment of the hollow fiber membrane evaporative cooler, the outdoor air design conditions for summer air conditioning in five cities were simulated by an enthalpy difference laboratory. Subsequently, the effects of water and air flow rates on outlet air parameters and performance parameters were investigated by setting-up a hollow fiber membrane evaporative cooling experimental rig. It was found that the hollow fiber membrane evaporative cooler has good application prospects in hot–dry regions such as Lanzhou, Xi’an, Yinchuan, Urumqi, and Karamay. Among them, the hollow fiber membrane evaporative cooler has higher applicability in regions with higher air temperatures and lower humidity such as Urumqi and Karamay. The results indicate that the air outlet temperature and relative humidity ranged from 26.5 °C to 30.8 °C and 63.5% to 82.8%, respectively. The outlet air temperature and relative humidity of the HFMEC can meet the thermal comfort requirements of hot–dry regions in the summer at an appropriate air flow rate. The maximum air temperature drop, wet-bulb efficiency, cooling capacity, and COP were 7.5 °C, 62.9%, 396.4 W, and 4.81, respectively. In addition, the effect of the air flow rate on the performance parameters was more significant than that of the water flow rate.

Reading the Score of the Air—Change in Airborne Microbial Load in Contrast to Particulate Matter during Music Making

The potential impact of music-making on air quality around musicians was inferred at the outset of the SARS-CoV-2 pandemic from measurements on individual musical instruments and from theoretical considerations. However, it is unclear to what extent playing together in an orchestra under optimal ventilation conditions really increases infection risks for individual musicians. In this study, changes in indoor air quality were assessed by measuring common parameters, i.e., temperature, relative humidity, and carbon dioxide, along with particle counting and determining the presence of airborne pharyngeal bacteria under different seating arrangements. The study was conducted in cooperation with a professional orchestra on a stage ventilated by high volume displacement ventilation. Even with a full line-up, the particle load was only slightly influenced by the presence of the musicians on stage. At the same time, however, a clear increase in pharyngeal flora could be measured in front of individual instrument groups, but independent of seat spacing. Simultaneous measurement of various air parameters and, above all, the determination of relevant indicator bacteria in the air, enables site-specific risk assessment and safe music-making even during a pandemic.

Reduzierung von Versinterung durch optimierte Drainagebedingungen – Erkenntnisse eines Feldversuchs

AbstractA field test was carried out in Koralmtunnel in order to enhance process understanding and to optimize the drainage system in a tunnel section that is complex in terms of hydrochemistry, water inflow and mineral (calcareous scale, iron ochre) and biological (microbial mats) deposits. The field test comprised three test fields with different system components and flow characteristics. The development of critical waters and deposits was recorded by continuous measurements of relevant water and air parameters by means of autonomous sensors/data loggers. Furthermore, the components were ”forensically“ examined with respect to scale formation. The experiments show the crucial importance of gas exchange (CO2, oxygen ingress), filling level (flow geometry/regime), residence time of waters and water‐air interaction in the drainage system. The type, material consistency, and amount of scale and biofilms depend significantly on specific gradients. Floating scale crusts formed in stagnant sections, biofilms and iron ochre deposits of soft consistency formed at higher flow rates. Seepage packs and siphons turned out to be potential sediment traps with decreasing flow‐through with no access. Drainage hoses and dimpled membranes tend to be beneficial because they can prevent air exchange at relatively high flow rates. High CO2 partial pressure within these components (measured and modeled) inhibits carbonate precipitation. The drainage system is locally designed as a series of direct cross‐drains with simple flow paths, restricted air exchange, precautionary cleaning access, and optional water hardness stabilization (liquid conditioning).

Multiple logistic regression based prediction of heat flow direction in an intake incline of shallow depth by integrating thermal flywheel effect: A case study

The diurnal changes of psychrometric conditions in a shallow intake incline of an Indian coal mine were investigated. On different days spread over thirteen months, 24-hour studies were conducted. Based on the findings, the cyclic behavior of the heat load was documented. The Kendall rank correlation analysis between heat parameters of surface air and the airway reveals that the wet-bulb depression of inlet air is the most important factor for air to rock heat transfer, while sensible heat of inlet air is dominating factor for rock to air heat transfer. A multiple logistic regression-based model was proposed for predicting the direction of heat flow. Using Youden's index, the optimal cut-off value for the model was determined to be 0.478. Performance evaluation of the proposed model on the testing dataset shows an F-score of 0.8182 and an accuracy of 80%.

A case study of thermal and humidity sensations in the smart building

Modern smart buildings are equipped with renewable energy systems and control units to optimise and minimise energy consumption. Thus, they enable to reduce CO2 emissions and help protect the environment. In the article thermal and humidity sensations of students in the smart, modern building have been presented and discussed. The analyses were done in three lecture rooms, where students filled in questionnaires about how they felt. Simultaneously, indoor air parameters were measured (temperature, relative humidity, carbon dioxide level and etc.). The study enables to assess the thermal and humidity in the smart, modern building, where people tend to spend large amounts of time. Thus, the valuable data can be obtained regarding indoor environment and human responses there.

Pursuing occupants' health and well-being in building management: Definition of new metrics based on indoor air parameters.

The spread of COVID-19 has affected the lives of millions of people. Pandemic has made people more sensitive to health issues. In particular, the growing concern for the virus spread in confined spaces has promoted the necessity to improve indoor air quality. Literature is stressing how buildings must be designed and operated pursuing occupants’ health and well-being, with a particular attention for indoor air parameters. This poses the challenge of monitoring and assessing these aspects through proper metrics. In this paper the approach towards a multi-step assessment procedure embedding in buildings assessment health and well-being related variables and indicators is elaborated. They are intended to inform a building manager of the potential influence of air conditions on human health and well-being. Moreover, a set of monetary metrics (i.e., impacts) is proposed to translate energy and indoor air related building performances into euros, putting the basis for a comprehensive economic evaluation. The application of the set of proposed metrics to an Italian hotel (i.e., Italian pilot of H2020 MOBISTYLE project), enabled to map some indoor air conditions causing health concerns, and to identify clusters of guests with best and worst indoor air conditions, to be targeted by new management strategies. Despite case study specific limitations, the application exemplified how the methodology can expand the traditional energy-based performance assessment for building management towards indoor air domain and the related economic impacts, with implication on results in terms of overall economic performance of the building from both a private and public perspective.

Frost prevention research of the enthalpy wheel in air conditioning systems and industrial heat recovery systems

Enthalpy wheels are often used for air dehumidification and waste heat recovery. Application scenarios include air conditioning systems and industrial systems.Frost formation inside the enthalpy wheel is common in cold climates and has serious impacts on operational reliability and heat recovery performance. It is found that frost type, frosting area and frosting limit vary between different scenarios. Experimental and numerical investigations are conducted in the present research. For a certain wheel, inlet parameters of supply air and outlet parameters of exhaust air are the key factors influencing frosting formation. The enthalpy wheel will operate regularly without frost formation if exhaust temperature is higher than the frosting limit. Reducing the enthalpy wheel rotation speed below 6 rpm is an effective method to prevent the enthalpy wheel from frosting, but heat recovery efficiency is correspondingly reduced. Industrial systems are less affected by the cold climate, especially at higher exhaust air temperatures. Even if the climate temperature drops to −30 °C, the heat recovery efficiency can still exceed 85%. The research is anticipated to be useful for the application of enthalpy wheels in cold climates.

Experimental investigation of dehumidification performance of a vapor compression refrigeration system

The dehumidification performance of a vapor compression refrigeration system (VCRS) is investigated in this work, including total refrigerating capacity (TRC), total dehumidification capacity (TDC), latent heat ratio (RLH), and power consumption per unit dehumidification capacity (PCPDC). Experiments were performed for the VCRS with the rated refrigerating capacity of 7 kW. The influence of indoor air parameters including the temperature, humidity and flowrate on the dehumidification performance were studied. TDC and RLH decreased with an increase in the air temperature at a fixed humidity ratio, and increased with an increase in the air humidity at a fixed temperature. PCPDC decreased with an increase in the air humidity. The effect of the air flowrate was more complex than that of the air temperature and humidity. There was a maximum value in TDC and a minimum value in PCPDC with an increase in air flowrate for each humidity. For example, TDCmax was 2.45 kg/h for 38% rh and 6.62 kg/h for 80% rh, accordingly, PCPDCmin was 3383.48 kJ/kg for 38% rh and 1286.5 kJ/kg for 80% rh at 26 °C. As the humidity increases, the maximum and minimum values shifted towards larger flowrates. The experimental results are useful for the operation of VCRS and the design and control of convection-radiation air conditioning (CRA/C) system for the improvement of the environmental comfort.

Effects of small-scale storage on the cooking property and fatty acid profile of sea rice paddy

This research investigated the storability of sea rice paddy in an experimental silo for 11.5 months. Water was circulated in the silo walls from June 30 to maintain a grain bulk temperature of 23°C. The dry-bulb temperatures in three layers (top, middle, and bottom) of paddy bulk showed very small differences, but the intergranular air parameters such as relative humidity (RH), wet-bulb temperature and humidity ratio in middle and bottom bulk layers were significantly higher than those of top bulk layer, and storage insects occurred in these two bulk layers from August to September as a result that sulfuryl fluoride gas fumigation was done on September 30. During storage, the rice's water absorption rate and gruel solids loss decreased with storage time, while the peak temperature of gelatinization (Tp) increased, and water uptake ratio and taste panel score remained unchanged. Fatty acid profile analysis shows that the total, saturated, and unsaturated fatty acid concentrations decreased with storage time, while the unsaturated-to-saturated fatty acid ratio increased. Compared to top bulk layer, the bottom layer had lower water absorption rate and fatty acid concentration, and a similar Tp and better cooking property. Further compared with a short-grain Japonica paddy (cv. Yanfeng) stored in a large cooled warehouse before and after oversummering, sea rice paddy stored in the experimental silo had lower protein content, but had a higher Tp, poly-unsaturated fatty acid content and unsaturated-to-saturated fatty acid ratio, and similar amylose content and taste panel score. These results suggest that sea rice has good storability, and quasi-low-temperature storage (23°C) requires autumn chemical fumigation to control the storage insects.

Initial Desorption of Reaction Beech Wood

The research aimed to obtain empirical data for modeling the initial desorption in reaction wood from the cross-section of the green beech (Fagus sylvatica L.) log. Firstly, we analyzed the chemical composition, macro and microscopic structure of tension and opposite wood tissue. Then, the Equilibrium Moisture Content (EMC) was measured by the Dynamic Vapor Sorption method during the initial desorption. The used air parameters were specific for the mild drying schedule of green beech timber (t = 20, 35, and 50 °C, Relative Humidity (RH) ranging from 95 to 0 %). Relationships between the EMC of reaction wood and drying parameters were modeled using the Response Surface Method (RSM). The tests revealed: different hygroscopic properties of tension and opposite wood, the dependence of EMC value on temperature, and differences between EMC values for initial (first) and second desorption. Moreover, it was confirmed that, during initial desorption, the EMCs of reaction wood are significantly higher than reference EMC data. The differences in the EMC value are up to 0.14 kg/kg (for air with RH above 90 %). The presented polynomial model of the initial desorption of reaction beech wood can improve drying schedules for beech sawn timber with a high amount of reaction tissue.

Application of the cybernetic approach to price-dependent demand response for underground mining enterprise electricity consumption

The article considers a cybernetic model for the price-dependent demand response (DR) consumed by an underground mining enterprise (UGME), in particular, the main fan unit (MFU). A scheme of the model for managing the energy consumption of a MFU in the DR mode and the implementation of the cybernetic approach to the DR based on the IoT platform are proposed. The main functional requirements and the algorithm of the platform operation are described, the interaction of the platform with the UGME digital model simulator, on which the processes associated with the implementation of the technological process of ventilation and electricity demand response will be simulated in advance, is shown. The results of modeling the reduction in the load on the MFU of a mining enterprise for the day ahead are given. The presented solution makes it possible to determine in advance the necessary power consumption for the operation of the main power supply unit, manage its operation in an energy-saving mode and take into account the predicted changes in the planned one (e.g., when men hoisting along an air shaft) and unscheduled (e.g., when changing outdoor air parameters) modes. The results of the study can be used to reduce the cost of UGME without compromising the safety of technological processes, both through the implementation of energy-saving technical, technological or other measures, and with the participation of enterprises in the DR market. The proposed model ensures a guaranteed receipt of financial compensation for the UGME due to a reasonable change in the power consumption profile of the MFU during the hours of high demand for electricity, set by the system operator of the Unified Energy System.

Estimation of Energy Profile and Possible Energy Savings of Unclassified Buildings

In the European Union, only 1% of the building stock is renovated every year. According to the EU strategy, around 75% of the existing building stock needs to be renovated by 2050. Energy efficiency programs mainly support residential and public building stocks; this article considers military dormitories as a type of unclassified building. It is very important to improve energy efficiency to reduce energy consumption and improve the microclimate in these buildings, since the staff is there 24/7. This paper analyzes the energy consumption and measures the indoor air quality in 13 nonrenovated military dormitories. The personnel in unclassified buildings have limited options for remote work in the case of COVID-19 outbreak. Thus, the retrofitting and maintenance of such buildings must be planned carefully. There is a significant lack of IAQ measurements in unclassified buildings. This study presents a wide analysis of energy consumption, indoor air parameters, and occupant satisfaction. On the basis of real data, four retrofitting scenarios were evaluated in IDA ICE dynamic simulation software. The simulation results showed that, in the case of a deep renovation scenario, the theoretical energy savings could be 77.6–79.3% of the used energy. This paper discusses the solar energy potential of onsite energy production for increasing the efficiency and energy supply resilience of unclassified buildings. The results of this study can be applied to other countries with climate conditions similar to Latvia.

Ventilation impacts on infection risk mitigation, improvement of environmental quality and energy efficiency for subway carriages

Subway carriages are enclosed for extended periods of time, with a high density of passengers. Providing a safe, healthy, and comfortable cabin environment is a great challenge, particularly during the COVID-19 pandemic. An increase in ventilation rate can potentially reduce infection probability, which may result in worsening environmental quality (e.g., thermal comfort) and larger energy consumption. Thus, exploring the trade-off among infection risk, environmental quality (with regard to ventilation, thermal comfort, and air quality), and energy consumption is important to optimize ventilation systems for carriages. The effect of different supply air parameters (e.g., velocity and temperature) and ventilation modes of mixing ventilation (MV) & Supply air from the Floor and Return air from the Ceiling (SFRC) was studied. The questionnaires were analyzed to explore passenger dissatisfaction with the carriage environment using a MV system. Simulations were performed to predict the velocity, temperature, and CO2 concentration fields. In addition, the comprehensive benefit was evaluated by analytic hierarchy process (AHP), based on infection probability from the revisited Wells–Riley equation, Air Diffusion Performance Index (ADPI), Predicted Mean Vote (PMV), Pollutant Removal Effectiveness (PRE) and energy consumption estimated by cooling load (Lcool). Compared with MV, the optimized SFRC provided softer draft sensation and decreased CO2 concentration by 42%. The SFRC achieved better comprehensive benefits, with an infection risk reduced to 0.4%, ADPI of 80%, PMV approaching zero, PRE up to 16, and energy efficiency increased by 30%. This work contributes to the optimal design of subway carriage ventilation systems in the post-epidemic era.

Investigation of the lateral ventilation system in a poultry house using CFD

Maintaining a normalised microclimate in a poultry house is one of the main factors. It is the quality indicators of air parameters that ultimately determine the quality of product output. Keeping poultry requires considerable efforts and technological solutions. In this regard, the purpose of the study is to improve the microclimate system in the poultry house by installing ventilation equipment on the side wall. A powerful tool for predicting the air flow pattern in a poultry house is Computational Fluid Dynamics (CFD) modelling using ANSYS Fluent. This is an alternative to experimental research. CFD modelling results have shown that the valves operate most efficiently at 330 mm from the ceiling. The pressure drop of the supply valves is 45.85 Pa. The air velocity at the inlet of the supply valves is 9.17 m/s. The air velocity at a height of 0.7 m from the floor level varies within 0.57 m/s, the temperature – 9.91°C

SHOPPING MALL AIR PARAMETERS MEASUREMENT SYSTEM SYNTHESIS

The article is devoting to a shopping mall air parameters monitoring system creation. It is stated that increasing energy production, the world's population and harmful emissions into the atmosphere requires identifying solutions for searching and reducing the human activities impact on the environment. This issue is urgent because of the fact that environment harmful changes are irreversible. It is known that one of the options for harmful parameters values obtaining information is the construction and implementation of measurement systems, that are called weather stations. Literature review showed that available weather environment stations of temperature and humidity measuring only for the general purposes are designed. It limits the number of parameters that can be measured. The main parameters of the indoor environment that affect human health have been identified. It has been found that high concentrations of some gases can be dangerous for human health. It is shown that the issue of proper operation of the ventilation and air conditioning system and measuring its performance is an urgent task. The main requirements for the weather stations construction were obtained. Microcontroller and sensors synthesis for the weather station construction is made. The structural scheme and the scheme of connection of sensors are developed. The major attention is paid to the algorithms description that shows how air parameters system measurement works. The software system using the selected controller and sensors has been tested. A visualization of displaying the obtained shopping center air parameters has been developed. Based on received data the possibility of carrying out measurements on real object of management is confirmed.

Performance Analysis of the Multi-Stage Dew-Point Indirect Evaporative Air Cooler

In this study, a multi-stage regenerative-cross-flow dew-point evaporative cooler performance is analyzed and compared to the performance of a regenerative dew-point evaporative cooler. The most beneficial configuration of the proposed exchanger was established on the basis of its geometry and performance analysis using validated numerical models. For specific outlet air parameters, it was found that the multi-stage cooler with a working-to-primary air-flow ratio equal to 0.3 reaches 5.6% lower outlet air temperatures and 10.2% higher cooling capacity when compared to the regenerative unit. The proposed cooler provides lower outlet air temperatures for all average outdoor air parameters in selected locations, for both dry and humid outdoor air parameters (e.g., Denver (USA) and Izmir (Turkey)).