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1
Li, Kang, Hao Gao, Peng Jia, Lin Su, Yidong Fang, Hua Zhang e Ni Liu. "Numerical and experimental investigation on the air flow characteristics of heating, ventilation, and air-conditioning module for a small electric vehicle". Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 234, n. 6 (24 dicembre 2019): 1597–609. http://dx.doi.org/10.1177/0954407019895148.
Testo completoAbstract (sommario):
In electrical vehicles, replacing positive temperature coefficient heater as heat source with an air source heat pump could improve the driving range and decrease energy consumption in cold climate. Design of the heating, ventilation, and air-conditioning module for heat pump system has a significant influence on its performance in each working mode. A newly designed heat pump heating, ventilation, and air-conditioning module was introduced in this paper. The air flow characteristics of the heat pump heating, ventilation, and air-conditioning module in four working modes were analyzed, and the air flow rate and wind resistance were obtained by numerical simulation. Experiments were also conducted for validating its airflow rate in each working mode. Results of these experiments show that some unfavorable phenomena such as flow maldistribution and vortex inside the heat pump heating, ventilation, and air-conditioning module exist, which could lead to insufficient utilization of the heat exchange area of heat exchangers and the generation of aerodynamic noise. Furthermore, the air flow rate of the original heating, ventilation, and air-conditioning module was also measured for comparison, and the designed heat pump heating, ventilation, and air-conditioning module shows nearly 15–20% decrease in each working mode.
2
Voronuk, Andrey. "About Secondary Energy Resources, Heat Exchange Ventilation". Electronics and Control Systems 1, n. 71 (27 giugno 2022): 43–49. http://dx.doi.org/10.18372/1990-5548.71.16823.
Testo completoAbstract (sommario):
The article deals with life support systems, the main purpose of such systems is to make the building suitable for human life, or to create comfortable conditions for work. To create a favorable environment, optimal temperature and humidity in all residential and industrial premises, ventilation and air conditioning systems are used. The main goal of the work was the development of a high-tech energy-saving ventilation and air conditioning system with a modern automated control system. At the same time, the main directions of modernization of energy-saving control systems were developed, the hardware support of the energy-saving ventilation system was developed, the choice of the type of recuperator as an energy conservation subsystem was justified, the main elements of the system were calculated, the components of the ventilation and air conditioning system were modeled, a model of the supply-exhaust ventilation system was developed, and experimental tests were carried out research.
3
Fan, Hong Ming, Kai Yuan He, Zhi Fang Yin e Dan Zhang. "Transient Numerical Simulation for Air Distribution of Air Conditioning and Ventilation in Subway Island-Platform". Advanced Materials Research 250-253 (maggio 2011): 3107–14. http://dx.doi.org/10.4028/www.scientific.net/amr.250-253.3107.
Testo completoAbstract (sommario):
The typical subway island-platform of Beijing as research object was present in the article. Taking two-equation turbulence model and giving boundary conditions of piston wind and train heat load change with the time, adopting numerical method simulates air distribution of air-conditioning and ventilation system in subway. The results indicate that piston wind effect has significant impact on the area of platform entrance and staircase entrance while station with safety doors can obstruct piston effect at a certain degree. Simultaneity, the supply- exhaust air system offers relatively uniform temperature and velocity field, which meets requirements of transitory comfort for passengers. It is found that numerical simulation method can simulate and forecast air distribution of air conditioning and ventilating system in subway station. In conclusion, it can provide the reference for optimizing air-conditioning and ventilation system, improving thermal environment designing of subway station.
4
Zhao, Jing Bo. "Heat Storage Composite Wall, Ventilation Application". Advanced Materials Research 608-609 (dicembre 2012): 1737–40. http://dx.doi.org/10.4028/www.scientific.net/amr.608-609.1737.
Testo completoAbstract (sommario):
The article mainly describes the complex wall in the building structure design and thermal storage wall is arranged on the application; composite wall laid in phase change heat storage module technology; heat storage composite wall summer application characteristics and feasibility; soil air exchanger application and building air conditioning system energy saving effect. Full description of composite wall in different seasons of the feasibility and effect of energy saving.
5
Bezrodny, M. K. "THE HEAT PUMP SYSTEM FOR VENTILATION AND AIR CONDITIONING INSIDE THE PRODUCTION AREA WITH AN EXCESSIVE INTERNAL MOISTURE GENERATION". Eurasian Physical Technical Journal 17, n. 2 (24 dicembre 2020): 78–86. http://dx.doi.org/10.31489/2020no2/78-86.
Testo completoAbstract (sommario):
The paper studies application feasibility and energy efficiency of the ventilation and air conditioning heat pump system for maintaining comfort conditions inside the production area with an excessive internal moisture generation during the warm season. In this regard, a thermodynamic analysis of a heat pump system with a partial exhaust air recirculation and a variable ratio of fresh outside air was carried out. Numerical analysis was then done to estimate the influence of changes in the environment temperature and relative humidity and the characteristics of the ventilation and air conditioning object on the system parameters. This allowed to determine potential capabilities of this system to maintain comfortable conditions in the production area. It was also shown that the required additional cooling of the supply air at the entrance to the premise for air conditioning demands can be determined by a simple coefficient and its calculation method is provided in the article. The heat pump system of temperature and humidity maintenance has the highest energy efficiency in the zone of relatively low environment temperatures and largely depends on the relative humidity of the outside air. This suggests that the studied system is suitable for application in countries with temperate continental climate.
6
Fisher, G., B. Ligman, T. Brennan, R. Shaughnessy, B. H. Turk e B. Snead. "Radon Mitigation in Schools Utilising Heating, Ventilating and Air Conditioning Systems". Radiation Protection Dosimetry 56, n. 1-4 (1 dicembre 1994): 51–54. http://dx.doi.org/10.1093/oxfordjournals.rpd.a082421.
Testo completoAbstract (sommario):
Abstract As part of a continuing radon in schools technology development effort, EPA's School Evaluation Team has performed radon mitigation in schools by the method of ventilation/pressurisation control technology. Ventilation rates were increased, at a minimum, to meet the American Society of Heating, Refrigeration and Air Conditioning Engineers (ASHRAE) standard Ventilation for Acceptable Indoor Air Quality (ASHRAE 62-1989). This paper presents the results and the preliminary evaluations which led to the team's decision to implement this technology. Factors considered include energy penalties, comfort, indoor air quality (IAQ), building shell tightness, and equipment costs. Cost benefit of heat recovery ventilation was also considered. Earlier results of the SEP team's efforts have indicated a severe ventilation problem within the schools of the United States. An integrated approach to radon mitigation in schools and other large buildings which control radon as well as improve overall IAQ should be the goal of radon remediation where practical. Two case studies are presented where HVAC technology was implemented for controlling radon concentrations. One involved the installation of a heat recovery ventilator to depressurise a crawl space and provide ventilation to the classrooms which previously had no mechanical ventilation. The other involved the restoration of a variable air volume system in a two-storey building. The HVAC system's controls were restored and modified to provide a constant building pressure differential to control the entry of radon. Pre-mitigation and post-mitigation indoor air pollutant measurements were taken, including radon, carbon dioxide (CO2), particulates, and bio-aerosols. Long-term monitoring of radon, CO2 building pressure differentials, and indoor/outdoor temperature and relative humidity is presented.
7
DOVLATOV, IGOR M. "Indoor air-conditioning system for cattle houses". Agricultural Engineering, n. 3 (2023): 5–12. http://dx.doi.org/10.26897/2687-1149-2023-3-5-12.
Testo completoAbstract (sommario):
Creating comfortable conditions for animals ensures their longevity and high productivity. Artificial ventilation, which includes supply and exhaust systems and a control system, minimizes the influence of the human factor on maintaining the indoor air parameters. The proposed system of indoor air-conditioning for the loose cattle housing layout was developed based on the analysis of ventilation systems of livestock premises and studies proving the effectiveness of dehumidification in winter using a regenerative heat exchanger. The system for providing indoor air parameters was developed using the computer-aided design program “Compass” (CAD) of the “Askon” company. The developed system for providing indoor air parameters for keeping cattle includes an electrofilter and a coarse filter, fans, a plate heat exchanger, a turbodefector; temperature, humidity, and air flow velocity sensors, dust collectors, a pump, a tank with a disinfectant, and a mechanism for shutting down supply air and recirculated air. The use of a recuperative dehumidification system at low outdoor temperatures helps maintain the relative indoor humidity within the regulatory limits (75…40%) and reduce the concentration of carbon dioxide by 20…45%. To ensure these indoor air parameters without dehumidification, 200 kW of thermal power is needed to heat the supply air. The proposed combined energy-saving all-season climate control system provides monitoring of indoor air parameters and energy saving through the use of a turbo deflector, disinfects the ventilation air, dehumidifies the air in the cowshed in winter and cools in summer, and also partially removes dust from the air with an electromagnetic filter.
8
Łuczak, Rafał, Bogusław Ptaszyński, Zbigniew Kuczera e Piotr Życzkowski. "Energy efficiency of ground-air heat exchanger in the ventilation and airconditioning systems". E3S Web of Conferences 46 (2018): 00015. http://dx.doi.org/10.1051/e3sconf/20184600015.
Testo completoAbstract (sommario):
In the article, analysis of heat exchangers, working together with air-conditioning system, are presented. For an object with known requirement to hot and cold, air heat exchanger (ground type) is designed. For that defined system, the energy analysis of heat exchanger’s energy work in yearly cycle, including a work of air treatment with full (cooling - desiccation and heating of air in the summer, heating and moisturizing in the winter) and not quite full (cooling of air in the summer, heating of air in the winter) air-conditioning are examined. Effects connected with a reduction of energy costs needed for heat treatment of air blown to the room are specified included the climatic conditions like air heating and cooling degree-hours.
9
Il'ina, T., M. Kolesnikov e I. Kryukov. "ON INTEGRATED HEATING, VENTILATION AND AIR CONDITIONING SYSTEMS IN ROOMS OF SHOPPING CENTERS". Construction Materials and Products 3, n. 4 (2 novembre 2020): 39–47. http://dx.doi.org/10.34031/2618-7183-2020-3-4-39-47.
Testo completoAbstract (sommario):
the paper considers a method for creating microclimate parameters in the rooms of shopping centers, sports complexes, etc. The possibility of using a complex system including air heating, ventilation and air conditioning is shown on the example of a shopping hall. To improve the efficiency of the system, it is proposed to replace traditional water heating with air heating, which works by using a gas burner-heat exchanger. For the rooms of a shopping center in the city of Saint Petersburg, the thermal engineering calculation of external fences was performed, and the heat capacity of the heating system was determined. Based on the results of the heat and air balance of the grocery shopping area, the performance of the ventilation and air conditioning system is calculated. An autonomous monoblock unit for air treatment was selected. During the cold period, the unit performs the functions of air heating and ventilation. Air recirculation is provided to save heat energy. The amount of outdoor and recirculating air is calculated. During the warm period, air is cooled and dehumidified by using a compression refrigeration cycle. The proposed integrated system for creating the required parameters of the microclimate allows reducing material costs by using a gas burner-heat exchanger instead of a heat point for water heating, as well as using a cheaper energy source and heat recovery through a heat pump.
10
Bravo-Hidalgo, Debrayan. "Night air conditioning of buildings by external air ventilation". Revista Facultad de Ingeniería 27, n. 48 (5 maggio 2018): 35–47. http://dx.doi.org/10.19053/01211129.v27.n48.2018.8462.
Testo completoAbstract (sommario):
Buildings contain the environment in which almost all human activities take place, and therefore, nowadays, they represent a great sink of energy. Establishing thermal comfort conditions within these buildings is responsible for a large portion of their energy demand. This paper aims at providing a theoretical framework of the performance and the trends in research and implementation of night air conditioning by outside air ventilation. The bibliographic search was conducted in the academic directory Scopus, and the information extracted was processed in the VOSviewer software, through which text mining, map of terms and networks of investigative action were carried out. The literature showed that direct ventilation has a more significant cooling potential in regions characterized by a high difference between day and night air temperatures. The effectiveness of night cooling and the reliable prediction of thermal behavior are strongly related to the model adopted for the convection algorithm. A reliable prediction of heat transfer by convection requires an approach based on computational simulations of fluid dynamics, which are much more demanding in terms of computational power, compared to simulations of the variation of energy flows as a function of time. Most studies showed that the position of the thermal mass is not significant, while the amount of ventilation air is of great importance. In particular, the energy demand for cooling a building decreases sharply if the air flow rates increase.
11
Yin, Haiguo, Angui Li, Linna Li e Rui Wu. "Performance Evaluation of An Innovative Column Attachment Ventilation". E3S Web of Conferences 111 (2019): 01028. http://dx.doi.org/10.1051/e3sconf/201911101028.
Testo completoAbstract (sommario):
An innovative column attachment ventilation (CAV) was proposed for heating, ventilating and air-conditioning (HVAC) systems and its performance was evaluated through experimental investigation and numerical modeling. Airflow pattern, air temperature distribution, air diffusion performance index (ADPI), predicted mean vote (PMV), and draught rate (DR), were used as the performance indicators to investigate the air distribution performance. The ventilation effectiveness for heat removal in the CAV mode was compared with a conventional mixing ventilation (MV). The results showed that the discharged air from the linear slot diffuser can attach to the column and enter into the occupied zone creating air lake phenomenon. The airflow spread over the floor in a radial pattern behaved as a stratified air distribution like displacement ventilation (DV), providing good air quality and comfort level for occupants. Moreover, the heat removal effectiveness in the CAV was found to be higher than in the MV, i.e. 1.32 in the C-CAV and 1.29 in the S-CAV modes. The column attachment ventilation can achieve thermal comfort in the occupied zone without local discomfort caused by high vertical temperature difference and draught, and this ventilation strategy could be expected as a new and efficient air distribution pattern for different HVAC applications.
12
Diga, Dina, Irina Severin e Nicoleta Daniela Ignat. "Quality Study on Vehicle Heat Ventilation and Air Conditioning Failure". Sustainability 13, n. 23 (4 dicembre 2021): 13441. http://dx.doi.org/10.3390/su132313441.
Testo completoAbstract (sommario):
The automotive industry has set a highly demanding standard to meet customer satisfaction. The paper aimed to detail how quality analysis has been conducted to state the main causes that generated nonconformities of heat, ventilation and air conditioning (HVAC) systems. Problems have been reported on HVAC systems, such as noise, not being cold enough and moldy smell issues. All three problems determined by customer reports initiated the first contribution of this paper, namely by an initial quality study, and generated the investigation using is/is not problem scoping, data analysis, and graphical analysis. Pareto analysis and the Plan, Do, Check and Act (PDCA) approach are used to highlight the traceability of the actions performed in the evaluation of the problems and the detection of the causes related to each problem. The data analysis process and the data obtained from the analysis are the core of this paper. An immediate action plan is proposed, concluding with the hypothesis that the root cause is the blockage of the heater. This methodology has significant potential for being implemented, even for other components in the same industry or different sectors.
13
Besler, Maciej, Wojciech Cepiński e Piotr Kęskiewicz. "Direct-Contact Air, Gravel, Ground Heat Exchanger in Air Treatment Systems for Cowshed Air Conditioning". Energies 15, n. 1 (30 dicembre 2021): 234. http://dx.doi.org/10.3390/en15010234.
Testo completoAbstract (sommario):
This paper describes the analysis of the possibility of use of the direct-contact air, gravel, ground heat exchanger (acronym GAHE), patented at the Wroclaw University of Science and Technology, as a means of improving microclimate parameters in dairy cows’ barns. Different possibilities of introducing GAHE to the standard mechanical ventilation system of cowsheds have been proposed and investigated. Based on literature data, the required air parameters in the barns of dairy cows were determined and discussed. Computer simulations were carried out and the results obtained were compared to the baseline model. Year-round changes in microclimate parameters, especially air temperature, relative humidity, and THI index were investigated. The benefits of GAHE use were indicated. The possible increase in the minimum air volume of ventilation during the winter season and the decrease in the maximum values of this parameter in the summer were presented. Indications were made of the systems where the application of GAHE could be the most beneficial. A further research path has been proposed.
14
Yau, YH, e M. Ahmadzadehtalatapeh. "The empirical study of a four-row heat pipe heat exchanger to predict the year-round energy recovery in the tropics". Building Services Engineering Research and Technology 32, n. 4 (23 febbraio 2011): 307–27. http://dx.doi.org/10.1177/0143624410397919.
Testo completoAbstract (sommario):
The effect of heat pipe heat exchanger on the heat recovery was studied in the tropics. The performance of the heat exchanger was monitored during the one week of operation (168 h) to find out the performance characteristic curves. Three coil face velocities namely, 2, 2.2 and 2.5 m/s were tested and the temperature of return air was controlled at 24°C. The relevant empirical equations were then employed for the hour-by-hour prediction of the energy recovery by the heat pipe heat exchanger for the whole year. The impact of inside design temperature on the heat recovery by the heat exchanger was also studied. The thermal performance of the heat pipe heat exchanger was simulated based on the effectiveness-NTU method and the theoretical values were compared with the experimental data. Practical application: Performance improvement of the heating, ventilating and air conditioning systems is a challenge to the designers. The results obtained from this research work could serve as a practical guide for engineers who are intending to use heat pipe heat exchangers in the heating, ventilation and air conditioning systems operating in tropical climates. Engineers and researchers have the potential to use the recommended empirical performance equations to examine the impact of heat pipe heat exchangers on the performance of the current air conditioning systems. Moreover, these empirical performance equations enable the year-round operating effect of heat pipe heat exchangers on energy savings to be predicted realistically.
15
Shodiyev, Bobur, Nizomjon Usmonov, Alisher Davirov, Rakhimjon Kobilov e Rano Tukhtaeva. "A review of heat recovery technology for passive ventilation applications". E3S Web of Conferences 434 (2023): 01034. http://dx.doi.org/10.1051/e3sconf/202343401034.
Testo completoAbstract (sommario):
Regenerative heat exchangers are widely used in life support systems, gas turbines, boilers and other high-temperature industrial installations. These heat exchangers are used for cooling and heating gases, humidification and dehumidification of gases, heat recovery from high-potential heat carriers. Today, the increase in energy consumption and the increase in energy prices require a large-scale energy-saving policy in the creation of modern engineering structures – residential, commercial and industrial facilities alike. When designing and creating life support systems to save energy, it is advisable to use secondary energy resources, such as, for example, the heat of the air removed from the room. The energy intensity of conventional ventilation systems is on average 50–80% of the total energy intensity of the engineering systems of the facility where they are operated. The use of rotating regenerative heat exchangers in ventilation and air conditioning systems makes it possible to return up to 85% of heat to the system at a relatively low capital investment. In this regard, when improving such systems, considerable attention should be paid to the calculation, optimization and increase in the efficiency of heat exchangers. Thus, this work is about increasing the efficiency of rotating regenerative heat exchangers in ventilation and air conditioning systems.
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Zhang, Zi Jing, Bo Wen e Zhi Dong Lv. "Design of Air-Conditioning System and Ventilation System in Web Press Workshop of One Printing Plant". Applied Mechanics and Materials 256-259 (dicembre 2012): 2640–43. http://dx.doi.org/10.4028/www.scientific.net/amm.256-259.2640.
Testo completoAbstract (sommario):
Air-conditioning and ventilation system which control temperature and humidity was designed in this paper. Its aim was to ensure the production process and meet the comfort requirements of workers. Considering that web press equipment load account for large proportion of the total load, we separated out the area of web press and the waste heat was discharged by ventilation system. We adopted Stratified air conditioning on the remaining area because the whole workshop is large space. By means of calculation, energy saving rate of stratified air conditioning system is 25.6% and the refrigerating capacity is reduced by this way of design. Energy-saving effect is remarkable. So it’s a good method to energy conservation.
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Areimi, Mohammed Juma Al, e Anbu Clemensis Johnson. "Simulation Study of Air Conditioning System Location in Commercial Kitchen". International Journal of Emerging Technology and Advanced Engineering 10, n. 10 (25 ottobre 2020): 57–61. http://dx.doi.org/10.46338/ijetae1020_09.
Testo completoAbstract (sommario):
Working in a commercial kitchen in restaurants and hotels is physically challenging. In the Middle East, summer temperatures are very high and require proper ventilation and air conditioning for comfortable working. In the current study a typical kitchen with dimensions 5 m × 4 m × 3 m, with heat source and range hood is modelled using computational fluid dynamics software. A comparative analysis was conducted on the location of the air conditioning system in the kitchen space. The investigated locations of the air conditioning system were on the kitchen side wall and ceiling. The results of the simulation showed that placing the air conditioning system in the ceiling at the centre of the kitchen produced better air circulation. The air flow close to the hood had sufficient velocity to remove heat, contaminants and CO2 generated from the cooking process
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Pawar, Sharad, Chetan Mamulkar, Prajakta Kamane, Shubham Shelki, Priya Dighore e Ashwin Singh. "Air Conditioning Heat load Analysis of a Cabin". International Journal for Research in Applied Science and Engineering Technology 11, n. 5 (31 maggio 2023): 3225–31. http://dx.doi.org/10.22214/ijraset.2023.52305.
Testo completoAbstract (sommario):
Abstract: Air conditioning, often abbreviated as A/C (US), AC (US), or air con (UK), is the process of removing heat from an enclosed space to achieve a more comfortable interior environment (sometimes referred to as "comfort cooling") and in some cases also strictly controlling the humidity of internal air. Air conditioning can be achieved using a mechanical 'air conditioner' or alternatively a variety of other methods, including passive cooling or ventilative cooling. Air conditioning is a member of a family of systems and techniques that provide heating, ventilation, and air conditioning (HVAC). Heat pumps are similar in many ways to air conditioners, but use a reversing valve to allow them to heat and also cool an enclosed space. Air conditioners, which typically use vapor-compression refrigeration, range in size from small units used within vehicles or single rooms to massive units that can cool large buildings. Air source heat pumps, which can be used for heating as well as cooling, are becoming increasingly common in cooler climates. According to the International Energy Agency (IEA), as of 2018, 1.6 billion air conditioning units were installed, which accounted for an estimated 20% of electricity usage in buildings globally with the number expected to grow to 5.6 billion by 2050. The United Nations called for the technology to be made more sustainable to mitigate climate change and for the use of alternatives, like passive cooling, evaporative cooling, selective shading, windcatchers, and better thermal insulation. CFC and HCFC refrigerants such as R-12 and R-22, respectively, used within air conditioners have caused damage to the ozone layer, and HFC refrigerants such as R-410a and R-404a, which were designed to replace CFCs and HCFCs, are instead exacerbating climate change. Both issues happen due to the venting of refrigerant to the atmosphere, such as during repairs. HFO refrigerants, used in some if not most new equipment, solve both issues with an ozone damage potential (ODP) of zero and a much lower global warming potential (GWP) in the single or double digits vs. the three or four digits of HFCs.
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Muramatsu, Hiroshi, e Tatsuo Nobe. "Evaluation of Thermal Behavior of the Skeleton in a Green Building with the Aid of TABS". E3S Web of Conferences 111 (2019): 01085. http://dx.doi.org/10.1051/e3sconf/201911101085.
Testo completoAbstract (sommario):
In this study, an office building in Japan that incorporates energy-saving features and environmental technologies was investigated. This office building features a green façade, natural ventilation, a concrete slab with no suspended ceilings, and thermo-active building systems. Two airconditioning systems were installed in this building—a ceiling radiation air-conditioning system and a whole floor-blow off air conditioning system. In addition, a natural ventilation system was installed. We surveyed the heat flux of the ceiling surface and indoor thermal environment of this building from 2015 through 2016. The ceiling using the heat storage amount of concrete maintains a constant temperature in the workplace during as well as after office hours. We also performed detailed measurements of the heat flux of the ceiling surface and indoor thermal environment in the summer of 2017. The results showed that the ceiling radiation air-conditioning system provided a stable thermal environment. Furthermore, we report that making use of the thermal behavior of the skeleton improved the operation of the ceiling radiation airconditioning system.
20
Xiang, Huang, Wei Wang e Sheng Wu. "Analysis of Internet Bar Use Evaporative Air-Conditioning and Ventilation of Thermal Comfort". Advanced Materials Research 393-395 (novembre 2011): 1106–9. http://dx.doi.org/10.4028/www.scientific.net/amr.393-395.1106.
Testo completoAbstract (sommario):
The factors affecting indoor thermal environment are briefly introduced in this article, and one Internet bar was tested and analyzed that used evaporative air-conditioning in lanzhou, gansu. Meanwhile, through the air temperature, the relative humidity and air velocity of sensitivity factors were analyzed that heat sensation to human body, changed the heat sensation for people's from qualitative to the quantitative. As one way and the basis has provided for the improvement room internal heat environment quality.
21
Hussain, Taliv. "Performance evaluation of hybrid desiccant air conditioning system regenerated by waste heat from air cooled condenser: Experimental Investigation". IOP Conference Series: Materials Science and Engineering 1224, n. 1 (1 gennaio 2022): 012014. http://dx.doi.org/10.1088/1757-899x/1224/1/012014.
Testo completoAbstract (sommario):
Abstract Heating ventilation and air conditioning units reject a large quantity of heat to the surroundings as waste. Thus proper reclamation of this unused heat could also enhance the COP of such arrangements and their lesser adverse effect on the environment. Therefore hybrid desiccant air conditioning unit using unused heat from condenser for regeneration can be more effective than the conventional air conditioning unit under hot and humid climatic conditions. In this paper, various performance parameters of hybrid desiccant air conditioning unit using unused heat from condenser is determined at different process air inlet temperatures (28, 29.5, 31, 32.5, 34, 35.5 and 37°C) and different process air inlet velocities, i.e. (1.5, 2.5, 3.5 and 4.5 m/s) and at fix (2.5 m/s) air velocity at regeneration inlet. Refrigerating effect, heat rejection rate, VCOP, ECOP, dehumidification effectiveness, moisture removal capacity and DCOP decreases with increment in different air temperatures at process inlet. While compressor work, regeneration effectiveness and regeneration rate increases with increment in different air temperatures at process inlet. On the other hand, refrigerating effect, heat rejection rate, VCOP, ECOP, dehumidification effectiveness, regeneration effectiveness, and regeneration rate decrease with increased air velocities at process inlet. Whereas compressor work, moisture removal capacity and DCOP increases with an increase in air velocities at the process inlet. Thus, optimization of these performance parameters is determined to achieve the maximum efficiency of the hybrid desiccant air conditioning system under the above operating states.
22
Bezrodny, M., e T. Misiura. "HIGHLY EFFICIENT HEAT PUMP VENTILATION AND AIR CONDITIONING SYSTEM OF THE PRODUCTION AREA WITH VENTILATION AIR RECIRCULATION". POWER ENGINEERING: economics, technique, ecology, n. 2 (23 dicembre 2020): 26–35. http://dx.doi.org/10.20535/1813-5420.2.2020.220707.
Testo completo
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Duh, Feng-Chyi. "Transient Effects of Different Ventilation Methods on Car Indoor Air Quality". Studies in Engineering and Technology 2, n. 1 (15 luglio 2015): 70. http://dx.doi.org/10.11114/set.v2i1.891.
Testo completoAbstract (sommario):
This study investigated transient effects on the air quality of parked cars and moving cars with and without operating air conditioning. Carbon dioxide, carbon monoxide, volatile organic compounds, and formaldehyde concentrations were measured for comparative analysis. The results showed that simply changing the air conditioning system from internal circulation to external circulation to introduce air from outside reduces carbon dioxide concentrations by more than 50%, volatile organic compound concentrations by more than 77%, and the heat index from 0.1℃/min to less than 0.05 ℃/min. In order to conserve energy and improve car indoor air quality, this study can serve as a reference on healthy car environments.
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Gao, Jun, Jia-ning Zhao, Xiao-dong Li e Fu-sheng Gao. "A Zonal Model for Large Enclosures With Combined Stratification Cooling and Natural Ventilation: Part 1—Model Generation and its Procedure". Journal of Solar Energy Engineering 128, n. 3 (3 agosto 2005): 367–75. http://dx.doi.org/10.1115/1.2188958.
Testo completoAbstract (sommario):
This paper describes a combined system of stratificated air conditioning and natural ventilation for large enclosures, which uses stratificated air conditioning to cool the occupied part of a space and uses natural ventilation to cool the upper part to reduce heat penetration into the lower air-conditioned part. A zonal model is constructed to predict the vertical temperature profiles of large enclosures under such a combined system. This model incorporates airflow and heat transfer throughout the space into the mass and heat balance equations for each horizontally settled zone. It introduces some particular flow dynamics and thermal effects into the predictions of mean airflows and temperature distributions. Different from those pressure-based zonal models applied generally to the predictions for small building rooms, it is termed a temperature-based zonal model, which uses correlations based on temperature differences in combination with submodels for modeling of mass flow and heat transfer in the large enclosures. The present paper provides a calculation procedure for the model. Model performances are then discussed through analyzing the impacts of some influential factors on the space air temperature profiles.
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Xue, Guiyuan, Chen Wu, Wenjuan Niu, Xun Dou, Shizhen Wang e Yadie Fu. "Flexible Control Strategy for Intelligent Building Air Conditioning System". E3S Web of Conferences 252 (2021): 01039. http://dx.doi.org/10.1051/e3sconf/202125201039.
Testo completoAbstract (sommario):
An improved optimization adjustment strategy for building heating ventilation and air conditioning (Heating Ventilation and Air Conditioning, HVAC) is proposed. The energy consumption model of building heating/refrigeration is established by using the instantaneous energy balance of heat, and then the optimal operation strategy of building HVAC energy based on weather forecast data is constructed in the range of user temperature comfort. Finally, the MATLAB and TRNSYS simulation techniques are used to verify the example. Simulation results show that the optimal operation strategy of building HVAC energy based on weather forecast data can not only significantly reduce the cost of energy use, but also effectively improve the absorption capacity of renewable energy on the building side.
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Cappenberg, Audri Deacy. "PERENCANAAN SISTEM PENYEGARAN UDARA UNTUK RUANG KELAS FAKULTAS TEKNIK UTA’45 JAKARTA". JURNAL KAJIAN TEKNIK MESIN 3, n. 1 (29 maggio 2019): 9–20. http://dx.doi.org/10.52447/jktm.v3i1.1104.
Testo completoAbstract (sommario):
The comfort of classroom have a big impact to the studying activity or other activity inside the classroom, that is why an air conditioning system should be planned while taking a lot of factors such as from inside and outside thr room into account, based on the calculation that has been done, it was found that the ventilated air that’s needed in the classroom is 4,1295 L/S, sensibel ventilation heat load for 25 persons of 2035 W, heat load generated for the north wall 80,64 W, east of 145,15 and west of 112,857 W. indoor heat load of 2649,87 W and outdoor heat load of1957,529 W. so the total capacity of the air conditioning is 4607 W
27
Li, Li, Qing Ling Zhang e Ya Ping Li. "Application of an Air-Air Energy Exchanger in a Building HVAC System in Xiamen". Applied Mechanics and Materials 170-173 (maggio 2012): 2474–77. http://dx.doi.org/10.4028/www.scientific.net/amm.170-173.2474.
Testo completoAbstract (sommario):
An air-air energy exchanger (AAEE) has been introduced in the literature as a novel energy recovery system that transfers heat and moisture between the ventilation and exhaust air. In this paper, the application of an AAEE in a HVAC system is investigated. The paper discusses the dependency of AAEE performance on ventilation air and indoor and outdoor air conditions, it describes how to control the AAEE in different operating conditions (summer and winter). The suited meteorological conditions of the AAEE in buildings are given. Based on the humidity and temperature data of the typical meteorological year in Xiamen, the temperature distribution statistics throughout the year is studied and the air enthalpy difference is calculated. Combining with the demand of the indoor air conditioning parameters, the applicable hours of different types of AAEE, such as total heat and sensible heat, in Xiamen are analyzed. It is shown that the lower we intend to get the temperature and relative humidity, the more space there will be for the AAEE to work in summer. In winter, for the sensible heat AAEE, the higher indoor temperature we design, the more hours it works, the greater space we will have for heat recovery. But for the total heat AAEE, it will be used longer as the indoor temperature and relative humidity are designed higher. The study results show that the AAEE can be energy-saving and reduce indoor air pollution of modern buildings, improve indoor work and living environment. The result can provide basic principle and referenced data for product improvement and air-conditioning system design.
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Murakami, Ko, Kenta Sakai, Daisuke Nakamura, Haruno Ishikawa, Sayana Tsushima e Shin-ichi Tanabe. "A Field Survey on Indoor Air Pollution in School Classrooms with Different Ventilation Methods". E3S Web of Conferences 111 (2019): 01020. http://dx.doi.org/10.1051/e3sconf/201911101020.
Testo completoAbstract (sommario):
The purpose of this study was to investigate the actual indoor air quality within two elementary schools with different types of ventilation methods, and to obtain data pertaining to the emission of bioeffluents within the schools. Field surveys on indoor air quality were conducted at two public elementary schools in Tokyo, both equipped with air-conditioning systems. School-A was also equipped with a heat-exchange ventilation system, while School-B did not have a ventilation system. Results of the study revealed that the target ventilation volume for the heat-exchange ventilation system in School-A was not achieved, indoor air quality in School-B was better in relatively cool conditions than School-A because of the habit of opening windows attached, there was a positive correlation between nonanal and decanal and CO2 concentration in summer, and the concentration of bioeffluents nonanal and decanal may be higher at high temperatures even under the same level of ventilation.
29
Zhang, Chong, Jinbo Wang, Liao Li, Feifei Wang e Wenjie Gang. "Utilization of Earth-to-Air Heat Exchanger to Pre-Cool/Heat Ventilation Air and Its Annual Energy Performance Evaluation: A Case Study". Sustainability 12, n. 20 (10 ottobre 2020): 8330. http://dx.doi.org/10.3390/su12208330.
Testo completoAbstract (sommario):
An earth-to-air heat exchanger (EAHE) system utilizes the low-grade thermal energy of underground soil to warm up and cool down the flowing air within an underground buried pipe. Integrating the EAHE system with building ventilation can reduce the energy demand for conditioning ventilation air. The main purposes of this paper are to estimate the year-round energy-saving potential of the EAHE-assisted building ventilation system and provide its design guidelines in a hot-summer and cold-winter climate. A steady-state heat transfer model was proposed to calculate the outlet air temperature of an EAHE and further identify its ability to preheat and precool ventilation air. Influences of depth, length, and diameter of a buried pipe on the year-round thermal performance of the EAHE system were evaluated. The results show that considering the compromise between thermal performance and construction costs of the EAHE system, a depth of 5 m and a length of 80 m are recommended. The EAHE system can provide a mean daily cooling and heating capacity of 19.6 kWh and 19.3 kWh, respectively. Moreover, the utilization of the EAHE system can reduce by 16.0% and 50.1% the energy demand for cooling and heating ventilation air throughout the whole year.
30
Koshida, Moe, Tomohiro Kobayashi, Toshio Yamanaka, Narae Choi e Haruna Yamasawa. "Thermal Environment, Ventilation Effectiveness, and Infection Risk of Restaurant with Impinging Jet Ventilation". E3S Web of Conferences 396 (2023): 02031. http://dx.doi.org/10.1051/e3sconf/202339602031.
Testo completoAbstract (sommario):
The basic strategy of the impinging jet ventilation system (IJV) is to keep high air quality within the occupied zone. In IJV, the air supplied from ducts impinges on the floor and spread through the lower level of the room. When the air reaches the heat sources, it rises upward and is exhausted around the ceiling. Most of the previous works about IJV focus on simple room set-ups, whereas the studies focus on realistic set-ups are limited. To investigate the applicability of IJV to a more practical situation, CFD analysis was conducted in a room that simulated a restaurant. In this numerical study, thirty-two seated occupants were distributed in the restaurant hall as the heat and contaminant sources (contaminant was released from their mouth), while a large amount of heat was generated by the equipment in the kitchen. The indoor environment of IJV was compared to that of the mixing ventilation system (MV) in terms of thermal environment, ventilation effectiveness, and infection risk. The results showed that IJV were superior to MV in terms of air conditioning efficiency, pollutant removal efficiency, and infection risk reduction. In conclusion, the results suggest that IJV can improve the indoor environment.
31
V.I., Sinitcyn, e SHurshakova E.V. "The modern trends in the design of systems of heat and ventilation". Ekologiya i stroitelstvo 4 (2015): 15–17. http://dx.doi.org/10.35688/2413-8452-2015-04-003.
Testo completoAbstract (sommario):
The article presents the review and analysis of current trends in the design of systems of heat and ventilation. Examines two major trends in designing modern systems of heat and ventilation: the use of technologies that increase energy efficiency and improve environmental air conditions of buildings. It is noted that the development of technologies for processing air, increasing energy efficiency, continues to be a priority in the field of heating, ventilation and air conditioning. An important trend is the increased attention to the creation of ecology air mode in areas at early stages of development of the architectural concept of the building. Discusses the features and applications tipovyh pumps in buildings and facilities. Discusses the peculiarities of installing underground storage of heat and cold in aquifers, which have proliferated in recent years. The features of technology «cooling ceilings» to improve comfort levels in buildings.
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Güngör, Şahin, e Emre Taş. "Design and analytical investigation on air-to-air cross flow heat exchanger of an industrial heat recovery ventilation system". Scientia cum Industria 11, n. 1 (2023): e231103. http://dx.doi.org/10.18226/23185279.e231103.
Testo completoAbstract (sommario):
Energy consumption based on the building heating, ventilation, and air-conditioning (HVAC) systems is sharply rising daily. At this point, heat recovery ventilation systems save energy while contributing to indoor air quality and thermal comfort. This work mainly focuses on designing the air-to-air cross-flow heat exchanger system and duct lines. First, the ducts, bends, vents, and heat recovery ventilation unit are placed around the selected domain complying with the ASHRAE 55 and 62.1 standards. The requirements on temperature levels of the cold and hot streams, air flow rates, number of vents, velocity at the supply air vent outlets are considered. Then, calculations are conducted for the cross-flow air-to-air heat exchanger to determine the number of layers, heat transfer surface areas, flow regime, and heat transfer rate. Thermal calculations of the recuperator system are initially performed by effectiveness-number of transfer unit (ϵ-NTU) method as the outlet temperatures are not known at the beginning of the design. In addition, the findings are compared and validated via logarithmic mean temperature difference methodology. The results show that the fresh air temperature can increase from 5 °C to 13.32 °C when the exhaust air temperature is at 26 °C in winter. Furthermore, the heat transfer rate of air-to-air heat exchanger system is analytically calculated as 1806.7 W and 1807.5 W via ϵ-NTU and logarithmic mean temperature difference (LMTD) methods, respectively.
33
Kang, Byung Ha, e Hyun Jin Lee. "A Review of Recent Research on Automotive HVAC Systems for EVs". International Journal of Air-Conditioning and Refrigeration 25, n. 04 (dicembre 2017): 1730003. http://dx.doi.org/10.1142/s2010132517300038.
Testo completoAbstract (sommario):
Automotive heating, ventilation, and air-conditioning (HVAC) systems are of particular interest from the viewpoint of improving fuel economy, especially in electric vehicles (EVs) such as hybrid electric vehicles (HEVs), fuel cell electric vehicles (FCEVs), and battery electric vehicles (BEVs). This paper describes recent research on automotive air-conditioning and heating technologies after classifying them into heat pump applications, control and operation, heat exchangers, refrigerants, thermal comfort, localized HVAC systems, and additional energy-saving systems. Even though many researchers have applied the existing concepts and technologies for EVs, significant revamping efforts are necessary owing to the dynamic, transient, and local characteristics of vehicles.
34
Kozák, Pavol, e Danica Košičanová. "Investigation of the use of various materials for the construction of an enthalpy exchanger". Selected Scientific Papers - Journal of Civil Engineering 15, n. 2 (1 dicembre 2020): 75–94. http://dx.doi.org/10.1515/sspjce-2020-0021.
Testo completoAbstract (sommario):
AbstractConsidering the current gradual depletion of non-renewable primary sources, it is necessary to address the reduction of energy consumption in ventilation and air conditioning systems. Although heat recovery alone reduces the energy intensity of these systems, if moisture recovery is considered as well, the contribution in reducing energy consumption is significant. These are mainly the devices designed primarily for spaces where people stay permanently, which do not allow large fluctuations in temperature and humidity. In cooperation with the manufacturer of heat recovery exchangers, we determined our own method of comparing different types of materials that could be used to design an exchanger which would also allow moisture recovery. These results in a significant reduction in energy consumption used to humidify the air in ventilation and air conditioning systems. It is one of the possible ways how to compare individual samples that are being measured. This article primarily deals with the comparison of three different types of materials, out of the total number of twelve measured samples.
35
Dovgaliuk, Volodymyr, e Pavlo Lysak. "Influence of Visitors’ Flows on Indoor Air Quality of Museum Premises". Selected Scientific Papers - Journal of Civil Engineering 7, n. 1 (1 giugno 2012): 5–12. http://dx.doi.org/10.2478/v10299-012-0013-2.
Testo completoAbstract (sommario):
Abstract The article considers the influence of visitors’ flows on indoor air quality of museum premises and work of ventilation and air conditioning systems. The article provides the analysis of the heat input from visitors, the results of mathematical simulation of visitors flow influence on indoor air quality. Several advice options are provided on application of variable air volume systems for provision of constant indoor air quality.
36
Rimár, Miroslav, Andrii Kulikov, Marcel Fedak e Milan Abraham. "CFD analysis of the ventilation heating system". Mechanics & Industry 20, n. 7 (2019): 708. http://dx.doi.org/10.1051/meca/2020020.
Testo completoAbstract (sommario):
Air conditioning is a significant part of the contemporary life. A lot of the medical papers confirmed the influence of the thermal comfort to the operability. The aim of the article is to understand the system of the building ventilation with the HRV unit. For this purpose, the CFD simulation model was elaborated. The ANSYS Fluent allows to calculate the heat balance of the room with secondary thermal gains like computers, monitors and humans. The results of the simulation approved that in the modern thermal passive houses heat balance calculations should take into account secondary thermal gains from the installed equipment. Also the air circulation in the closed area and the influence of the different barriers installed in the laboratory were investigated.
37
Chicherin, Stanislav. "Analysis of procedures for heating, ventilation and air conditioning for transfer to low-temperature heat supply". Stroitel stvo nauka i obrazovanie [Construction Science and Education], n. 3 (30 settembre 2019): 8. http://dx.doi.org/10.22227/2305-5502.2019.3.8.
Testo completoAbstract (sommario):
Introduction. Renovation of housing stock supposes construction of new buildings, where the main utilities consuming heat energy will be heating and hot water supply (HWS) systems. Under such conditions the task of heat consumption reduction by transfer to low-temperature and use of the associated procedures is relevant. Materials and Methods. Research was performed on the basis of residential and administration buildings designed within the whole Russia, the facilities were selected based on the year of putting into operation and their purpose. The source of data concerning buildings became documents included into the scope of the design and detailed documentation: plans, drawings and explanatory notes. As meeting the demands of hot water supply makes the main contribution to daily nonuniformities of heat energy consumption, the attention was paid to equipment of hot water supply systems. For calculations, the commercial product of Microsoft Office Excel 2010 was used. Results. During selection of roof boiler house as a source of heat supply increase in consumption of equivalent fuel in relation to the variant of connection to heat power plant operating on solid fuel by 187,314 tons of fuel oil equivalent is possible. General refusal from power-and-heat generation complicates operation of large district heat supply systems. The design parameters of coolant in building heating system differ from project to project: from 95/70 °С, used everywhere till the beginning of the XXI century, up to 90/65 °С corresponding to existing practice of designing or 80/60 °С as at the facility in Sevastopol. Reduction of design temperatures by 5 % is insufficient to decrease general heat consumption of the building. Reduction of heat consumption is explained by selection of advanced materials for pipeline heat insulation. Use of automation diagrams for heat points on the basis of regulator ECL Comfort 310 contributes to improvement of hydraulic control for heating systems, however, concealed automation results in violation of high-quality mode for heat network control and decrease of coolant parameters on adjacent (often non-automated) consumers. Conclusions. Supplement of central high-quality control by local constant temperature/variable flow control at individual heat unit and installation of temperature controllers on heating radiators with mechanical thermostatic head have potential for reduction of the heat energy volume used ineffectively. Increase in level of controllability for heating system together with cheaper and responsive automation systems are basic conditions for increase in quality of heat supply in future.
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NISHIMURA, Nobuya, Ryoga FUKUSHO e Toshiki SAKANAKA. "Experimental Evaluation of Air-conditioning Waste Heat Recovery using Total Heat Exchanger in Mass Ventilation". Proceedings of the National Symposium on Power and Energy Systems 2022.26 (2022): E132. http://dx.doi.org/10.1299/jsmepes.2022.26.e132.
Testo completo
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Zhang, Yin, Xin Wang e Eric Hu. "Optimization of night mechanical ventilation strategy in summer for cooling energy saving based on inverse problem method". Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 232, n. 8 (29 marzo 2018): 1093–102. http://dx.doi.org/10.1177/0957650918766691.
Testo completoAbstract (sommario):
Night ventilation has great energy saving potentials for public buildings in summer. However, night mechanical ventilation inevitably causes more fan energy consumptions, even though it can reduce the cooling loads for the next day and save the air conditioning energy consumption correspondingly. Thus the optimization of night mechanical ventilation strategy is highly significant for building energy efficiency. In this paper, the simplified two-plate room model is used and the optimization model of the mechanical ventilation and air conditioning system is established. To minimize the total energy consumption, the optimal night ventilation strategy is determined through inverse problem method. Taking an office room in Beijing as the illustrative example, the results show that the optimal air exchange rate for night mechanical ventilation is much higher than the traditional value (ACH = 0.5 h−1) and it highly depends on the indoor-outdoor air temperature difference and cooling load demands. Moreover, the total electricity usage amount can decline from 210 kWh to 111 kWh after optimization, reduced by about 47% in the whole summer season. It also indicates that the energy saving effect of night ventilation mainly derives from the cooling storage and load shifting of building internal walls. Compared to traditional ventilation strategy, the energy saving ratio increases with increasing thermal conductivity and specific heat of building internal walls. This work can provide guidance for practical ventilation system optimization design and operation strategy determination.
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Borowski, Marek, Michał Karch, Sławosz Kleszcz, Paweł Sala e Grzegorz Waryan. "An experimental and numerical investigation of the thermal and non–thermal efficiency for counterflow heat exchanger". E3S Web of Conferences 128 (2019): 04008. http://dx.doi.org/10.1051/e3sconf/201912804008.
Testo completoAbstract (sommario):
Heating, ventilation and air conditioning systems are responsible for a significant part of total energy consumption in operated buildings. To decrease energy consumption in the near future, all buildings will have mechanical ventilation with heat recovery. In such system heat exchanger is the essential part of the system responsible for effective energy recovery from exhaust air. However, the main disadvantage of this type of unit is heat exchanger freezing during winter. To solve this issue in the present research a special air distribution system in the heat exchanger was developed. The periodic-flow unit under investigation consists of a standard counter flow heat exchanger and a set of opposing air dampers used to appropriately cyclically modify the direction of air flow through the heat exchanger. Proposed in the studies modification eliminate the negative aspect of unit freezing during the winter season as well as ensure proper air humidity. It has been found that the thermal efficiency for theheat exchanger is 83.5%. However, some internal leakage in manufactured unit occurs which artificiallyraised this parameter. The estimated value from the energy balance of was lower about 80.3%. The value of the heat exchanger efficiency falls within the range 80.3-82.8%.
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Syas, Isnan Yusrian, e Mohammad Kholid Ridwan. "Exergy Analysis of Air Conditioning (AC) System in Suite Room Santika Hotel Yogyakarta". IOP Conference Series: Earth and Environmental Science 927, n. 1 (1 dicembre 2021): 012043. http://dx.doi.org/10.1088/1755-1315/927/1/012043.
Testo completoAbstract (sommario):
Abstract Air Conditioning are major contributors to energy consumption in-suite room Santika Hotel Yogyakarta. A suite room is a choice of rooms with the best facilities compared to other rooms, so comfort is one of the services that must be optimized. The ain is to determine the conduction heat load of various components in the room. Heat conduction load calculation includes heat load through the glass on the east 1253.18 BTU/hr, conduction heat load through the wall to the south 606.14 BTU/hr, solar radiation through glass 1268.48 BTU/hr, heat gain from people 1980 BTU/hr, electrical equipment/lights 2193 BTU/hr and heat gain from ventilation 13053.6 BTU/hr. The total amount of heat gain used in exergy analysis calculation with a value of 3053.16 BTU/hr.
42
Si, Qiang, Jianjun Wei e Yuan Li. "Experimental study of condensation characteristics and operation strategies of induction radiant air-conditioning system". IOP Conference Series: Earth and Environmental Science 1101, n. 7 (1 novembre 2022): 072001. http://dx.doi.org/10.1088/1755-1315/1101/7/072001.
Testo completoAbstract (sommario):
Abstract To study the operation and condensation characteristics of an induction radiant air-conditioning system as a novel system that combines induction ventilation and radiant air conditioning, the characteristics of convection and condensation of an indoor terminal device radiant induction unit were studied. The mass transfer coefficient, condensation temperature, and condensation rate were analyzed experimentally. The time required to achieve a steady state indoor thermal environment was collected. The results indicated that the primary airflow rate and temperature mainly affected the mass transfer coefficient, condensation temperature, and condensation rate. When the indoor thermal environment reached a steady state, the heat transfer performance of the radiant induction unit was mainly affected by the primary air temperature. When condensation occurred, the primary airflow rate had a greater influence on the condensation rate. The start-up and response performances of the system were better than those of a traditional radiant air-conditioning system. In the condensation condition, reasonable control strategies maintain the primary air temperature and adjust the primary air flow rate, which can ensure sufficient heat transfer and stabilize the indoor thermal environment faster.
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Hurnik, Maria, Joanna Ferdyn-Grygierek, Jan Kaczmarczyk e Piotr Koper. "Thermal Diagnosis of Ventilation and Cooling Systems in a Sports Hall—A Case Study". Buildings 13, n. 5 (29 aprile 2023): 1185. http://dx.doi.org/10.3390/buildings13051185.
Testo completoAbstract (sommario):
Air conditioning systems in buildings consume a significant part of the world’s energy, and yet there are cases wherein users are not satisfied with the quality of the thermal environment. Examples of such special cases are sports halls, which require different thermal conditions within a single zone. Thermal diagnostics for buildings can be used to diagnose problems. The aim of the paper was to analyse the effectiveness of the ventilation and cooling systems of a sports hall with a cubature of 16,300 m3 and to check the possibility of managing the hall’s cooling demands via the existing air conditioning system. Diagnostic measurements were performed, including in situ measurements of ventilation air flows from the diffusers and their temperatures, visualization of the supply air flows, and monthly registration of the indoor temperature in the hall at different set temperatures of the supply and exhaust air. Additionally, a numerical analysis, using EnergyPlus simulations, of cooling demand was performed with regard to the varying uses of the hall. The analysis based on measurement and simulation showed that it is not possible to remove heat gains from the hall with the current available ventilation air flow.
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Bonuso, Sara, Simone Panico, Cristina Baglivo, Domenico Mazzeo, Nicoletta Matera, Paolo Maria Congedo e Giuseppe Oliveti. "Dynamic Analysis of the Natural and Mechanical Ventilation of a Solar Greenhouse by Coupling Controlled Mechanical Ventilation (CMV) with an Earth-to-Air Heat Exchanger (EAHX)". Energies 13, n. 14 (16 luglio 2020): 3676. http://dx.doi.org/10.3390/en13143676.
Testo completoAbstract (sommario):
Greenhouse crops represent a significant productive sector of the agricultural system; one of the main problems to be addressed is indoor air conditioning to ensure thermal well-being of crops. This study focuses on the ventilation analysis of solar greenhouse with symmetrical flat pitched roof and single span located in a warm temperate climate. This work proposes the dynamic analysis of the greenhouse modeled in TRNsys, simultaneously considering different thermal phenomena three-dimensional (3D) shortwave and longwave radiative exchange, airflow exchanges, presence of lamps with their exact 3D position, ground and plant evapotranspiration, and convective heat transfer coefficients. Several air conditioning systems were analyzed, automatic window opening, controlled mechanical ventilation systems (CMV) and horizontal Earth-to-Air Heat Exchanger (EAHX) coupled with CMV, for different air volume changes per hour. In summer, the exploitation of the ground allows having excellent results with the EAHX system, reducing the temperature peaks of up to 5 °C compared to the use of CMV. In winter, it is interesting to note that, although the EAHX is not the solution that raises the temperature the most during the day, its use allows flattening the thermal wave more. In fact, the trend is almost constant during the day, raising the temperature during the first and last hours of the day.
45
Ma, Li, e Yuan Yuan Li. "The Air-Conditioning Rtilization of Natural Cold Resource of Lakes and Reservoirs". Advanced Materials Research 243-249 (maggio 2011): 6947–50. http://dx.doi.org/10.4028/www.scientific.net/amr.243-249.6947.
Testo completoAbstract (sommario):
In the reservoir water temperature conducted annual test, test data shows that water temperature perennial remain in 9 ~ 10 in certain depth below. Reservoirs and lakes are huge natural cold source. In an air conditioning engineering, the reservoir cold water was directly used as cooling source. The air conditioning effect is good and to gets good energy-saving and environmental benefits. It suggests that solar energy, natural ventilation and natural cold and heat storage in water should be widely used in the western tourist architecture in order to achieve low carbon tourism.
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Yezhov, V. S., N. E. Semicheva, D. N. Tyutyunov, A. P. Burtsev, N. S. Perepelitsa e A. P. Burtsev. "Mathematical Model for Automated Heat Flow Control of an EnergyEfficient Ventilation System". Proceedings of the Southwest State University 25, n. 1 (30 maggio 2021): 38–52. http://dx.doi.org/10.21869/2223-1560-2021-25-1-38-52.
Testo completoAbstract (sommario):
Purpose of research. In modern ventilation and air conditioning systems (VAC), one of the main components is an automatic control system (ACS) which performs various functions and also provides highly efficient operation in the range from shutdown functions to centralized regulation and control of climate parameters (temperature, humidity, monitoring concentrations of harmful substances, air speed). The goal is to study a mathematical model of heat flow control of a supply and exhaust ventilation system with a builtin integrated recuperative heat exchanger for the purpose of utilization of low-temperature heat of ventilation gases and emissions with the associated production of thermoelectricity.Methods. To achieve these goals, we used methods of mathematical simulation and computational model development. The automatic control of VAC is based on the principle of feedback – regulation of processes by obtaining information from external sensors based on mathematical simulation of physical processes occurring in the building or structure serviced.Results. An experimental supply and exhaust system with a plate heat exchanger-recuperator operates in a quasi-steady heat transfer mode. Exhaust air removed from the room is used as a heating medium. At the same time, the system is controlled using an independent scheme of connection to the heat supply system. The air heated in the room is considered as an incompressible gas, the heat exchange between the heating and heated heat transfer media is a steadystate process, the turbulence of the heating and heated flow of heat transfer media is isotropic. The result of the study is a mathematical model of heat flow control in the supply and exhaust ventilation system with a builtin integrated heat exchanger-recuperator. The optimal values of the heat energy consumed and the parameters of the ventilation system operation are obtained.Conclusion. A mathematical model of heat flow control in a supply and exhaust ventilation system with a builtin integrated heat exchanger-recuperator is proposed and investigated. The optimal values of the consumed heat energy and the parameters of the ventilation system operation are obtained.
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Oudjehani, N., K. Abahri, A. Tahakourt e Rafik Belarbi. "Evaluation of Earth-Air Heat Exchangers Efficiency in Hot and Dry Climates". Advanced Materials Research 739 (agosto 2013): 318–24. http://dx.doi.org/10.4028/www.scientific.net/amr.739.318.
Testo completoAbstract (sommario):
Energy efficiency of building, promotes strongly the integration of passive strategies, in order to achieve a thermal comfort especially in summer conditions by reducing or preventing the use of air conditioning systems. In this work, building energy performance has been evaluated using an earth-air heat exchanger (EAHE) during summer period. Energy requirements was analysis by the means of dynamic simulation tools called (TRNSYS) for hot and arid climate in the southern Algeria. This analysis was conducted function of different (such as soil typology, tube material, tube length and depth, ventilation airflow rates). Results show that earth-air heat exchanger has the highest efficiency for arid climates. Furthermore, the possibility of coupling of this technology with other passive strategies (nocturne ventilation and thermal mass) has been also examined. High efficiency was observed.
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Kumar, Dileep, Abdul Ghafoor Memon, Rizwan Ahmed Memon, Intizar Ali e Natasa Nord. "Parametric study of condensation at heating, ventilation, and air-conditioning duct's external surface". Building Services Engineering Research and Technology 39, n. 3 (9 dicembre 2017): 328–42. http://dx.doi.org/10.1177/0143624417743119.
Testo completoAbstract (sommario):
The compression of insulation causes around a heating, ventilation, and air-conditioning duct usually resulted in dew formation around the outer surfaces because of low temperature, which causes significant energy and financial losses. The parameters such as supply air flow rate, supply air temperature, ambient air speed, and the convective heat transfer coefficient (ho) plays significant role in dew formation. In this paper, the parametric study is performed to investigate the effects of these parameters on the external surface temperature of the duct to avoid condensation. A mathematical model is developed to quantify these effects using preliminary data obtained from the heating, ventilation, and air-conditioning system of a pharmaceutical company. The results reveal that external surface temperature increases with an increase in insulation thickness and supply air temperature, whereas it decreases with higher supply air flow rate. It is estimated that the minimum insulation thickness at joint and bend should be maintained between 15–55 and 15–35 mm, respectively, with a variation in ho between 6 and 22 W/m2K to avoid condensation. Additionally, it is estimated that air flow rate should be greater than 1.4 m3/s at 10 W/m2 K and 2.2 m3/s at 22 W/m2 K. Similarly, the ambient air speed should be greater than 2.8 m/s at 6 W/m2 K, respectively. Practical application: Building services engineers have a paucity of information on the effects of the compression of heating, ventilation, and air-conditioning duct thermal insulation. It can cause condensation that will adversely affect the insulation material, thereby increasing the maintenance cost as well increasing the heat loss from the duct so affecting the conditions of supply air. Proper insulation thickness and operating parameters are important for building owners and operators to control ongoing expenses of buildings. This paper seeks to quantify the effect of insulation compression to improve understanding so that this important area may be properly considered by the building services engineer.
49
Wu, Gui Xiang, Xiao Zhi Wang, Tao Yang, Da You e Wen Jiang Chen. "Numerical Simulation of Heat Pipe Heat Exchanger in Dedicated Ventilation System". Applied Mechanics and Materials 608-609 (ottobre 2014): 81–85. http://dx.doi.org/10.4028/www.scientific.net/amm.608-609.81.
Testo completoAbstract (sommario):
Independent dedicated ventilation system is an advanced air conditioning system developed in last few years. There is little research on the design of the system at present. This paper establishes control equation of flow and temperature field based on the energy transmission theory and simulates heat pipe independent dedicated ventilation system using special flow field numerical simulation software. In pretreatment process of FLUENT, this paper uses unstructured six prisms and parallelepiped grid and encrypts grid which makes the result of calculation is more accurate. The simulation uses residual of 10-5 high precision to calculate, and obtains the residual convergence curve. Curve analysis shows that the calculation is very reliable and stable. In post-treatment process, it uses FLUENT results processing module, obtains the temperature flow pattern of heat exchanger independent dedicated ventilation system. We take one of the root canal for analysis. The result shows that the temperature in both sides of the tube is higher, and the temperature through the tube and close to the wall part is lower. It is coincide with the actual working condition of tube ventilation and heat dissipation outside the pipe. This result proves the accuracy of the numerical simulation and provides the reliable theory basis for the design of heat pipe heat exchanger independent dedicated ventilation system.
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Zeng, Yun Fan, e Min Hui Zhang. "A Central Air Conditioning System Design for Guesthouse in Changsha City". Applied Mechanics and Materials 170-173 (maggio 2012): 2431–36. http://dx.doi.org/10.4028/www.scientific.net/amm.170-173.2431.
Testo completoAbstract (sommario):
This article presents the design of the air conditioning system in the building. In the project, ice storage for cold source and electric boiler thermal storage for heat source are taken while variable primary flow is used for water system. Taking into account the functions of each part, all air and fan coil unit with fresh air system are applied in ventilation system. The design of air exhaust system is introduced. A detail scheme about the annual operational regulation for energy saving is proposed. During the designing process, energy conservation is given enough attention, and the reliability of operation is also ensured.