Optimization of the Electric Vehicle HVAC Duct System Based on Gradient Method

Short Time ◽

Initial Geometry

Our study describes the optimization of the part of heating, ventilation and air conditioning (HVAC) system of an electric car. The geometry of the air duct connected to the heater unit on one side and the dashboard on the other. From the point of view of aerodynamics, it is necessary to change the geometry of the air duct so as to minimize the loss of air pressure and ensure a more uniform flow from the exit holes to improve the efficiency of windshield heating. In order to optimize the initial geometry of the air duct, approach of using gradient methods was applied. According to the results of the study, detailed concept of optimizing the air duct of an electric car is presented. The optimized geometry was tested with the use of methods of computational aerodynamics. Calculations were made as part of the interior model of electric car with the output of temperature fields on the windshield. The results can be applied to the design of heating, ventilation and air conditioning systems of vehicles in a short time.

Investigation on the Intake Process for a Theoretical Twin Opposite Piston Compressor Using R744 Refrigerant

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.823.75 ◽

2016 ◽

Vol 823 ◽

pp. 75-78

Author(s):

Doru Groza ◽

Dan Mihai Dogariu

Keyword(s):

Air Conditioning ◽

Piston Compressor ◽

Environmental Issues ◽

Point Of View ◽

Vapor Compression ◽

Household Appliances ◽

Intake Process ◽

Vapor Compression Refrigeration ◽

Energetic Point ◽

This study aims to validate the use of R744 for a resonant twin piston compressor for domestic applications. The vapor-compression refrigeration is the most commonly approached method for cooling household appliances such as refrigerators and air conditioning systems. The R134a refrigerant is one of the most suitable refrigerants from an energetic point of view. R744 (CO2) compressors are less efficient, but the fact that the R134a raises serious environmental issues pushes commercial trend towards the usage of R744 [1]-[3]. Use of R744 in household appliances is currently an open topic and no company has switched yet to the environmental-friendly alternative. In this paper the fill efficiency will be simulated in order to validate if a conventional compressor such as the opposite twin piston compressor is capable of filling with refrigerant when operating at a 50Hz frequency. Such a validation can enable further investigations regarding the replacement of R134a with R744.

Analysis of Common Problems of Noise and Vibration in Building Heating Ventilation Air Conditioning Design

E3S Web of Conferences ◽

10.1051/e3sconf/202128301051 ◽

2021 ◽

Vol 283 ◽

pp. 01051

Author(s):

Xiaolong Ruan ◽

Yisong Yin

Keyword(s):

Continuous Improvement ◽

Air Conditioning ◽

Preventive Measures ◽

Hvac System ◽

Continuous Growth ◽

Noise And Vibration ◽

Vibration Problems ◽

Common Problems ◽

And Control

With the continuous growth of my country's economy and the continuous improvement of the people's economic level, the demand for the design of heating, ventilation and air conditioning systems has also increased. The HVAC system is very important in the building environment. When optimizing the relevant design, it is necessary to always consider the design details of the HVAC system and adjust the integrity of the design, especially to take preventive measures in areas where noise and vibration may occur to avoid heating serious problems caused by noise and general vibration when the communication system is running. This article outlines how to avoid and control common noise and vibration problems when designing HVAC projects.

Development of Heating and Cooling Local Air Conditioning System for Houses

Materials Science Forum ◽

10.4028/www.scientific.net/msf.931.920 ◽

2018 ◽

Vol 931 ◽

pp. 920-925

Author(s):

Zohrab Melikyan ◽

Naira Egnatosyan ◽

Siranush Egnatosyan

Keyword(s):

Air Conditioning ◽

Point Of View ◽

Air Conditioner ◽

Air Conditioning System ◽

Air Conditioners ◽

Heating And Cooling ◽

The Creation ◽

Centralized air conditioning systems are widely used in buildings at present. In these conditioners, the outside air gets required temperature, humidity, purity, and other features, necessary for creating comfort microclimate in inside areas of houses, and by the help of fans and air ducts the processed air moves to all rooms of a building. As a result, the creation and maintenance of comfort conditions in buildings become complicated and expensive activity. From this point of view, it is becoming more expedient to install local air conditioners in each room instead of single central one for the whole building. For this reason new local air conditioner is developed.

Comparative Analysis of Energy Consumption, Indoor Thermal–Hygrometric Conditions, and Air Quality for HVAC, LDAC, and RDAC Systems Used in Operating Rooms

Applied Sciences ◽

10.3390/app10113721 ◽

2020 ◽

Vol 10 (11) ◽

pp. 3721

Author(s):

Tsung-Yi Chien ◽

Ching-Chieh Liang ◽

Feng-Jen Wu ◽

Chi-Tsung Chen ◽

Ting-Hsin Pan ◽

...

Keyword(s):

Energy Consumption ◽

Air Quality ◽

Air Conditioning ◽

Operating Rooms ◽

Conventional Heating ◽

Hvac System ◽

Total Energy Consumption ◽

System A ◽

Daily Total

As controlling temperature and humidity is crucial for maintaining comfort and preventing microbial growth, operating rooms (ORs) are the most energy-intensive areas in hospitals. We aimed to evaluate the energy consumption of three dehumidification air conditioning systems used in ORs and their corresponding air quality for ORs at rest. This study selected three ORs using a conventional heating, ventilation, and air conditioning (HVAC) system; a liquid desiccant air conditioning (LDAC) system; and a rotary desiccant air conditioning (RDAC) system, respectively. The indoor thermal–hygrometric conditions, air quality, and energy consumption of the ORs were monitored in this study. The median levels of relative humidity (RH) were 66.7% in the OR using the conventional HVAC system, 60.8% in the OR using the LDAC system, and 60.5% in the OR using the RDAC system. The median daily total energy consumption of the RDAC system (10.1 kWh/m2) and LDAC system (11.8 kWh/m2) were 28.12% and 16.54% lower, respectively, than that of the conventional HVAC system (14.1 kWh/m2). The PM≥0.5 levels and airborne bacterial concentrations in the ORs met the ISO 14644-1 Class 7 standard and China’s GB50333-2013 standard, respectively. The RDAC system was clearly superior to the LDAC and conventional HVAC systems in terms of energy consumption.

EFFICIENCY OF USING HEAT PUMPS IN AIR CONDITIONING SYSTEMS

Actual Issues Of Energy ◽

10.25206/2686-6935-2021-3-1-14-18 ◽

2021 ◽

Vol 3 (1) ◽

pp. 014-018

Author(s):

A. S. Kovaleva ◽

◽

I. A. KABANOVA ◽

◽

...

Keyword(s):

Heat Pump ◽

Air Conditioning ◽

Heat Pumps ◽

Economic Importance ◽

Point Of View ◽

Safe Operation ◽

Preliminary Study ◽

Working Agent ◽

Basic Configuration

This article discusses the relevance of the use of heat pumps in air conditioning systems. The features of the use of passive and active air conditioning schemes with the use of heat pumps are considered. The object of the study is the SCR of an administrative building in the basic configuration and with the use of a heat pump. For a comparative assessment of the energy efficiency of the SCR, a preliminary study was carried out on the choice of the working agent of the heat pump. The paper shows the technical and economic importance of using these circuit solutions for SCR from the point of view of solving energy saving issues and ensuring the safe operation of the system as a whole.

Reducing Virus Transmission from Heating, Ventilation, and Air Conditioning Systems of Urban Subways

10.21203/rs.3.rs-1164057/v1 ◽

2021 ◽

Author(s):

Ata Nazari ◽

Jiarong Hong ◽

Farzad Taghizadeh-Hesary ◽

Farhad Taghizadeh-Hesary

Keyword(s):

Air Conditioning ◽

Low Cost ◽

Infected Individual ◽

Virus Transmission ◽

Mean Value ◽

Hvac System ◽

Transit System ◽

Encounter Probability ◽

Flow Effects ◽

Abstract Transmission via virus-carrying aerosols inside enclosed spaces is an important transmission mode for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), as supported by growing evidence. The urban subway is one of the most commonly used enclosed spaces. The subway is a utilitarian and low-cost transit system in today’s society. However, studies are yet to demonstrate patterns of viral transmission in subway heating, ventilation, and air conditioning (HVAC) systems. To fill this gap, we performed a computational investigation of the airflow (and the associated aerosol transmission) in an urban subway cabin equipped with an HVAC system. We employed a transport equation for aerosol concentration, which was added to the basic buoyant solver to resolve aerosol transmission inside the subway cabin. This was achieved by considering the thermal, turbulence, and induced ventilation flow effects. Using the aerosol encounter probability over sampling lines crossing the passenger breathing zones, we can detect the highest infection risk zones inside the urban subway under different settings. We proposed a novel HVAC system that can impede aerosol spread, both vertically and horizontally, inside the cabin. In the conventional model, the maximum aerosol encounter probability from an infected individual breathing near the fresh-air ducts was equal to 15%. This decreased to 0.36% in the proposed HVAC model. Overall, using the proposed HVAC system for urban subways decreased the mean value of the aerosol encounter probability by approximately 79% compared to that for the conventional system.

Influence of air distribution in modern large university lecture hall on thermal comfort

International Review of Applied Sciences and Engineering ◽

10.1556/1848.2019.0010 ◽

2019 ◽

Vol 10 (1) ◽

pp. 63-69

Author(s):

Mária Budiaková

Keyword(s):

Thermal Comfort ◽

Distribution System ◽

Air Conditioning ◽

Distribution Systems ◽

Winter Season ◽

Point Of View ◽

Air Distribution ◽

Lecture Hall ◽

Globe Temperature ◽

The paper is focused on the influence of air distribution in modern large university lecture hall on the thermal comfort. Providing the optimal parameters of the thermal comfort in the interiors of a university is immensely important for the students. Meeting these parameters is inevitable not only from physiological point of view but also to achieve the desirable students' performance. Parameters of the thermal comfort are also influenced by air distribution system in large university lecture hall. Correct position of supply air and extract air is very important. Experimental measurements of thermal comfort were carried out in the winter season in the large lecture hall of Vienna University of Economics and Business. The device Testo 480 was used for the measurements. Obtained values of air temperature, air relative humidity, air velocity, globe temperature, indexes PMV and PPD are presented in the charts. Modern air distribution system and air conditioning system of the large university lecture hall were evaluated on the basis of thermal comfort parameters. Conclusion of this paper states the principles of how to design modern air distribution systems and air conditioning systems in the new large university lecture halls.

Energy, Economic and Environmental Effects of the Marine Diesel Engine Trigeneration Energy Systems

Journal of Marine Science and Engineering ◽

10.3390/jmse9070773 ◽

2021 ◽

Vol 9 (7) ◽

pp. 773

Author(s):

Ivan Gospić ◽

Ivica Glavan ◽

Igor Poljak ◽

Vedran Mrzljak

Keyword(s):

Diesel Engine ◽

Environmental Effects ◽

Air Conditioning ◽

Fruits And Vegetables ◽

Point Of View ◽

Air Conditioning System ◽

Absorption Cooling ◽

Marine Diesel ◽

Variable Energy

The paper discusses the possibility of applying the trigeneration energy concept (cogeneration + absorption cooling) on diesel-powered refrigerated ships, based on systematic analyses of variable energy loads during the estimated life of the ship on a predefined navigation route. From a methodological point of view, mathematical modeling of predictable energy interactions of a ship with a realistic environment yields corresponding models of simultaneously occurring energy loads (propulsion, electrical and thermal), as well as the preferred trigenerational thermal effect (cooling and heating). Special emphasis is placed on the assessment of the upcoming total heat loads (refrigeration and heating) in live cargo air conditioning systems (unfrozen fruits and vegetables) as in ship accommodations. The obtained results indicate beneficiary energy, economic and environmental effects of the application of diesel engine trigeneration systems on ships intended for cargo transport whose storage temperatures range from −25 to 15 °C. Further analysis of trigeneration system application to the passenger ship air conditioning system indicates even greater achievable savings.

The growth of mica polytypes as studied by conventional and high-resolution TEM

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100074690 ◽

1983 ◽

Vol 41 ◽

pp. 174-177

Author(s):

A. Baronnet ◽

M. Amouric

Keyword(s):

Water Pressure ◽

Point Of View ◽

Temperature Fields ◽

Natural Occurrence ◽

Growth Mechanisms ◽

Long Period ◽

High Resolution Tem ◽

Layer Stacking ◽

Experimental Works ◽

Potential Use

The origin of mica polytypes has long been a challenging problem for crystal- lographers, mineralogists and petrologists. From the petrological point of view, interest in this field arose from the potential use of layer stacking data to furnish further informations about equilibrium and/or kinetic conditions prevailing during the crystallization of the widespread mica-bearing rocks. From the compilation of previous experimental works dealing with the occurrence domains of the various mica "polymorphs" (1Mr, 1M, 2M1, 2M2 and 3T) within water-pressure vs temperature fields, it became clear that most of these modifications should be considered as metastable for a fixed mica species. Furthermore, the natural occurrence of long-period (or complex) polytypes could not be accounted for by phase considerations. This highlighted the need of a more detailed kinetic approach of the problem and, in particular, of the role growth mechanisms of basal faces could play in this crystallographic phenomenon.

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

Computational nanotechnology ◽

10.33693/2313-223x-2019-6-3-86-91 ◽

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 ◽

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.