scholarly journals Development of a laboratory nozzle chamber installation for the humidification of buildings

2021 ◽  
Vol 939 (1) ◽  
pp. 012025
Author(s):  
Kh Isakhodjayev ◽  
F Mukhtarov ◽  
D Kodirov ◽  
I Toshpulatov
Keyword(s):  
High Efficiency ◽  
Aerodynamic Resistance ◽  
Air Cooling ◽  
Spray Chamber ◽  
Cooling Mode ◽  
High Effect ◽  
Air Stream ◽  
Interfacial Surface ◽  
Central Air Conditioning ◽  
Air Conditioning Systems

Abstract The nozzle chamber, in which water is sprayed into the air stream using mechanical nozzles, is the main unit for these processes in central air conditioning systems (AHUs). The types of nozzles used do not have a sufficiently high effect of interfacial surface forming due to increased metal usage and the broad total dimensions of certain chambers, i.e., they do not have intensive heat and mass transfer. The authors performed testing of the apparatus in the direct iso-enthalpic air cooling mode to improve the performance of the nozzle chamber. Thus, the experiments conducted confirm the relatively high efficiency of FET operation at small values of irrigation coefficient B ≥ 1.0. The area highlighted is characterised by the unstable operation of other nozzle types. Therefore, FET nozzles can be operated at irrigation factor values B = 0.1…1.0. Experiments have shown that this equation is applicable for practical calculations, with a relative error of ±6.7%. The aerodynamic resistance of the spray chamber nozzle chambers is also according to the data not exceeding 160 Pa.

ANALYSIS OF COMPETING VARIANTS OF AIR CONDITIONING SYSTEMS WITHOUT AIR EXTRACTION FROM ENGINES AT THE STAGE OF PASSENGER AIRCRAFT ONBOARD SYSTEMS CONCEPTUAL DESIGN

2019 ◽  
Vol 6 (3) ◽  
pp. 80-85
Author(s):  
Denis Igorevich Smagin ◽  
Konstantin Igorevich Starostin ◽  
Roman Sergeevich Savelyev ◽  
Anatoly Anatolyevich Satin ◽  
Anastasiya Romanovna Neveshkina ◽  
...  
Keyword(s):  
Conceptual Design ◽  
Air Conditioning ◽  
Research University ◽  
Cooling System ◽  
Fuel Efficiency ◽  
Air Cooling ◽  
Moscow Aviation Institute ◽  
Air Conditioning System ◽  
Low Efficiency ◽  
Air Conditioning Systems

One of the ways to achieve safety and comfort is to improve on-board air conditioning systems.The use of air cooling machine determines the air pressure high level at the point of selection from the aircraft engine compressor. Because of the aircraft operation in different modes and especially in the modes of small gas engines, deliberately high stages of selection have to be used for ensuring proper operation of the refrigeration machine in the modes of the aircraft small gas engines. Into force of this, most modes of aircraft operation have to throttle the pressure of the selected stage of selection, which, together with the low efficiency of the air cycle cooling system, makes the currently used air conditioning systems energy inefficient.A key feature of the architecture without air extraction from the main engines compressors is the use of electric drive compressors as a source of compressed air.A comparative analysis of competing variants of on-board air conditioning system without air extraction from engines for longrange aircraft projects was performed at the Moscow Aviation Institute (National Research University).The article deals with the main approaches to the decision-making process on the appearance of a promising aircraft on-board air conditioning system at the stage of its conceptual design and formulated the basic requirements for the structure of a complex criterion at different life cycle stages.The level of technical and technological risk, together with a larger installation weight, will require significant costs for development, testing, debugging and subsequent implementation, but at the same time on-board air conditioning system scheme without air extraction from the engines will achieve a significant increase in fuel efficiency at the level of the entire aircraft.

Thermal Performance Evaluation of Friction Stir Welded Flat Plate Heat Sink Using CFD Analysis

2015 ◽  
Vol 787 ◽  
pp. 505-509
Author(s):  
A.K. Lakshminarayanan ◽  
M. Suresh
Keyword(s):  
Flat Plate ◽  
Heat Sink ◽  
High Efficiency ◽  
Base Plate ◽  
Software Tool ◽  
Cover Plate ◽  
Air Cooling ◽  
Cooling Systems ◽  
Plate Heat ◽  
Friction Stir

In an era of compact cooling requirements, where air cooling systems seem to be ineffective and consistently, being replaced by liquid cooled systems, with greater watt density heat energy dissipation. Such cooling systems must work with good quality enabling high efficiency. Hence, an attempt is made to fabricate an aluminum alloy based flat plate heat sink with cover and base plate using friction stir welding. The base plate is machined to obtain channels for fluid flow and the cover plate is fitted in the base plate and welded. Two such configurations of these heat sinks were fabricated with varying channel lengths and number of channels. The flow characteristics of the model for these configurations were analyzed numerically using computational fluid dynamics (CFD) software tool, ANSYS fluent 14.

scholarly journals Can Public Spaces Effectively Be Used as Cleaner Indoor Air Shelters during Extreme Smoke Events?

2021 ◽  
Vol 18 (8) ◽  
pp. 4085
Author(s):  
Amanda J. Wheeler ◽  
Ryan W. Allen ◽  
Kerryn Lawrence ◽  
Christopher T. Roulston ◽  
Jennifer Powell ◽  
...  
Keyword(s):  
Air Quality ◽  
Indoor Air ◽  
Air Conditioning ◽  
High Efficiency ◽  
Public Library ◽  
Public Building ◽  
Central Air Conditioning ◽  
The Media ◽  
The Impact ◽  
Pm2.5 Concentration

During extreme air pollution events, such as bushfires, public health agencies often recommend that vulnerable individuals visit a nearby public building with central air conditioning to reduce their exposure to smoke. However, there is limited evidence that these “cleaner indoor air shelters” reduce exposure or health risks. We quantified the impact of a “cleaner indoor air shelter” in a public library in Port Macquarie, NSW, Australia when concentrations of fine particulate matter (PM2.5) were elevated during a local peat fire and nearby bushfires. Specifically, we evaluated the air quality improvements with central air conditioning only and with the use of portable high efficiency particulate air (HEPA) filter air cleaners. We measured PM2.5 from August 2019 until February 2020 by deploying pairs of low-cost PM2.5 sensors (i) inside the main library, (ii) in a smaller media room inside the library, (iii) outside the library, and (iv) co-located with regulatory monitors located in the town. We operated two HEPA cleaners in the media room from August until October 2019. We quantified the infiltration efficiency of outdoor PM2.5 concentrations, defined as the fraction of the outdoor PM2.5 concentration that penetrates indoors and remains suspended, as well as the additional effect of HEPA cleaners on PM2.5 concentrations. The infiltration efficiency of outdoor PM2.5 into the air-conditioned main library was 30%, meaning that compared to the PM2.5 concentration outdoors, the concentrations of outdoor-generated PM2.5 indoors were reduced by 70%. In the media room, when the HEPA cleaners were operating, PM2.5 concentrations were reduced further with a PM2.5 infiltration efficiency of 17%. A carefully selected air-conditioned public building could be used as a cleaner indoor air shelter during episodes of elevated smoke emissions. Further improvements in indoor air quality within the building can be achieved by operating appropriately sized HEPA cleaners.

Numerical Simulation of Intermediate Cooling Temperature Field in Controlled Rolling

2010 ◽  
Vol 148-149 ◽  
pp. 359-362
Author(s):  
Wen Feng Huo ◽  
Xian Lei Hu ◽  
Bing Xing Wang ◽  
Xiang Hua Liu
Keyword(s):  
Cooling Rate ◽  
Controlled Rolling ◽  
Holding Time ◽  
Air Cooling ◽  
Thickness Direction ◽  
Cooling Mode ◽  
Cooling Strategy ◽  
Profile Characteristics ◽  
Intermediate Cooling ◽  
Rolling Efficiency

Air cooling may decrease rolling efficiency in controlled rolling for needing long holding time to obtain the correct rolling temperature because of small cooling rate. The intermediate cooling can increate the cooling rate, and improve rolling efficiency. Experiment was carried out to research the effect of intermediate cooling on rolling efficiency. The influence of different cooling mode on the temperature distribution and the temperature profile characteristics of different cooling strategy are analyzed with FEM. It shows that intermediate cooling can decrease the holding time effectively, and improve rolling efficiency; the temperature homogeneity in thickness direction can be improved by opening the header one after another and cooling the plate by oscillating cooling.

Characterization of Light Weight Heat Sink Materials for Thermal Management of Electronics

2007 ◽  
Author(s):  
Tunc Icoz ◽  
Mehmet Arik ◽  
John T. Dardis
Keyword(s):  
Thermal Management ◽  
Heat Sink ◽  
High Efficiency ◽  
Computational Study ◽  
Heat Sinks ◽  
Advanced Materials ◽  
Air Cooling ◽  
Thermal Management Of Electronics ◽  
Thermal Solution

Thermal management of electronics is a critical part of maintaining high efficiency and reliability. Adequate cooling must be balanced with weight and volumetric requirements, especially for passive air-cooling solutions in electronics applications where space and weight are at a premium. It should be noted that there are systems where thermal solution takes more than 95% of the total weight of the system. Therefore, it is necessary to investigate and utilize advanced materials to design low weight and compact systems. Many of the advanced materials have anisotropic thermal properties and their performances depend strongly on taking advantage of superior properties in the desired directions. Therefore, control of thermal conductivity plays an important role in utilization of such materials for cooling applications. Because of the complexity introduced by anisotropic properties, thermal performances of advanced materials are yet to be fully understood. Present study is an experimental and computational study on characterization of thermal performances of advanced materials for heat sink applications. Numerical simulations and experiments are performed to characterize thermal performances of four different materials. An estimated weight savings in excess of 75% with lightweight materials are observed compared to the traditionally used heat sinks.

Exergy Analysis of Energy Consumption for Central Air Conditioning System

2014 ◽  
Vol 628 ◽  
pp. 332-337
Author(s):  
Xiao Xia Xia ◽  
Nai Jun Zhou ◽  
Zhi Qi Wang
Keyword(s):  
Energy Consumption ◽  
Air Conditioning ◽  
Exergy Analysis ◽  
Exergy Efficiency ◽  
Dew Point ◽  
Exergy Loss ◽  
Air Conditioning System ◽  
Air Cooler ◽  
Central Air Conditioning ◽  
Air Conditioning Systems

The energy consumption of several central air conditioning systems in summer was researched by the method of exergy analysis. Combined with actual example,the exergy loss of all the equipments and the exergy efficiency of three systems were calculated. The results show that the exergy efficiency of three systems is very low. Relatively speaking, the exergy efficiency of primary return air conditioning system with supplying air in dew point is highest. The equipment of highest exergy loss is air-conditioned room, while the exergy loss of surface air cooler is smallest. Based on this, several improvement measures were proposed to reduce exergy loss and improve exergy efficiency.

Spreading of SARS-CoV-2 via Heating, Ventilation, and Air Conditioning Systems—An Overview of Energy Perspective and Potential Solutions

2020 ◽  
Vol 143 (8) ◽  
Author(s):  
Ahmad K. Sleiti ◽  
Samer F. Ahmed ◽  
Saud A. Ghani
Keyword(s):  
Air Conditioning ◽  
High Performance ◽  
Public Perception ◽  
High Efficiency ◽  
Uv Light ◽  
Experimental Studies ◽  
High Energy ◽  
Penalty Cost ◽  
Energy Penalty ◽  
Air Conditioning Systems

Abstract The role of heating, ventilation, and air conditioning systems (HVAC) in spreading SARS-CoV-2 is a complex topic and has not been studied thoroughly. There are some existing strategies and technologies for health and high performance buildings; however, applications to other types of buildings come at large energy penalty: cost; design, regulations and standards changes, and varied public perception. In the present work, different factors and strategies are reviewed and discussed and suggested mitigations and solutions are provided including the required air flowrates with the presence of infectors with and without mask and disinfection techniques including ultraviolet (UV) light. Experimental and numerical research in open literature suggests that the airborne transmission of SARS-CoV-2 is sufficiently likely. However, in situ detailed experimental studies are still needed to understand the different scenarios of the virus spread. Displacement ventilation, underfloor air distribution, chilled beams, radiant ceiling panels, and laminar flow systems have varied effectiveness. High-efficiency particulate arrestance (HEPA) filters and UV light can clean viruses but at high energy cost. Suggested solutions to reduce the infection probability include recommended levels of ventilation and a combination of virus sampling technologies including cyclones, liquid impinger, filters, electrostatic precipitators, and water-based condensation.

Preserving Passenger Comfort Through RWI Analysis

2012 ◽  
Author(s):  
Mark P. Colino ◽  
Elena B. Rosenstein
Keyword(s):  
Emergency Preparedness ◽  
Air Conditioning ◽  
Operating Pressure ◽  
Cooling Mode ◽  
Tunnel Ventilation ◽  
Passenger Comfort ◽  
Passenger Rail ◽  
Warmth Index ◽  
Emergency Events ◽  
Air Conditioning Systems

The air conditioning systems designed for passenger rail cars typically exchange heat with the outside air environment; when the trains operate within tunnels, the effectiveness of the air conditioning systems may diminish if the tunnel is too warm. Therefore, one of the traditional activation modes associated with rail tunnel ventilation systems is summertime cooling — for the purpose of maintaining onboard passenger comfort. However, summertime cooling modes can be problematic from the standpoints of fan operating pressure (i.e. an opposing air pressure is created whenever trains approach ventilation shafts), energy consumption and emergency preparedness (i.e. fans operating in the wrong direction when a fire is detected). In this paper, the thermal comfort of rail transportation passengers was studied in detail using the Relative Warmth Index (RWI) analyses to determine if the combination of: warm outdoor weather, the tunnel heat-sink effect, the rail coach design air temperature and typical commuting scenarios necessitated running the tunnel fans in a summertime cooling mode to preserve passenger comfort. If the summertime cooling mode could be eliminated, or even minimized, the tunnel ventilation usage/operating costs would be reduced, the fans would have a longer service life and the system would have greater overall availability for emergency events.

scholarly journals Possibilities of using solar energy in the processes of cooling external zones of people

2018 ◽  
Vol 49 ◽  
pp. 00016
Author(s):  
Ewelina Dec ◽  
Robert Sekret ◽  
Bożena Babiarz
Keyword(s):  
Solar Energy ◽  
Radiation Energy ◽  
Air Cooling ◽  
Cooling Systems ◽  
Maximum Daily Temperature ◽  
Air Temperatures ◽  
Technical Potential ◽  
Hot Days ◽  
Hot Weather ◽  
Air Conditioning Systems

Meteorological analyzes unambiguously indicate climate warming. An increase in average air temperatures is recorded in both winter and summer. In recent years, an increasing number of hot and very hot days are observed, and the duration of series of days with maximum daily temperature above 30°C is also longer. Occurrence of hot weather adversely affects the person staying outside. The ever-increasing requirements related to thermal comfort, enforce the provision of appropriate conditions not only in the rooms, but also in the external zones of people. Cooling the air in outdoor zones using standard air-conditioning systems can be expensive due to the high demand for electricity. Ensuring cooling through the use of renewable energy, such as solar energy, is a key solution to energy and environmental problems. In this article, the technical potential of solar radiation energy was determined based on data from the Rzeszow- Jasionka meteorological station and the possibilities of using solar energy in air cooling systems in external zones were presented.

scholarly journals A Numerical and Experimental Study of a Novel Heat Sink Design for Natural Convection Cooling of LED Grow Lights

Energies ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 4046
Author(s):  
Ram Adhikari ◽  
Dawood Beyragh ◽  
Majid Pahlevani ◽  
David Wood
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Heat Sink ◽  
Large Scale ◽  
High Efficiency ◽  
Experimental Testing ◽  
Growth Stages ◽  
Air Cooling ◽  
Convection Cooling ◽  
Heat Sink Design

Light-emitting diode (LED) grow lights are increasingly used in large-scale indoor farming to provide controlled light intensity and spectrum to maximize photosynthesis at various growth stages of plants. As well as converting electricity into light, the LED chips generate heat, so the boards must be properly cooled to maintain the high efficiency and reliability of the LED chips. Currently, LED grow lights are cooled by forced convection air cooling, the fans of which are often the points of failure and also consumers of a significant amount of power. Natural convection cooling is promising as it does not require any moving parts, but one major design challenge is to improve its relatively low heat transfer rate. This paper presents a novel heat sink design for natural convection cooling of LED grow lights. The new design consists of a large rectangular fin array with openings in the base transverse to the fins to increase air flow, and hence the heat transfer. Numerical simulations and experimental testing of a prototype LED grow light with the new heat sink showed that openings achieved their intended purpose. It was found that the new heat sink can transfer the necessary heat flux within the safe operating temperature range of LED chips, which is adequate for cooling LED grow lights.

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