scholarly journals ANALYSIS OF TEMPERATURE FIELD IN THE ROOM WITH VARIABLE THERMAL LOADS DURING THE AIR CONDITIONING SYSTEMS OPERATION

2020 ◽  
Vol 3 (79) ◽  
Author(s):  
Anna Moskvitina ◽  
◽  
Mariia Shyshyna ◽  
2019 ◽  
pp. 49-53
Author(s):  
Євген Іванович Трушляков ◽  
Микола Іванович Радченко ◽  
Андрій Миколайович Радченко ◽  
Сергій Георгійович Фордуй ◽  
Сергій Анатолійович Кантор ◽  
...  

Maintaining the operation of refrigeration compressors in nominal or close modes by selecting a rational design thermal load and distributing it in response to the behavior of the current thermal load according to the current climatic conditions is one of the promising reserves for improving the energy efficiency of air conditioning systems, which implementation ensures maximum or close to it in the annual cooling production according to air conditioning duties. In general case, the total range of current thermal loads of any air-conditioning system includes a range of unstable loads caused by precooling of ambient air with significant fluctuations in the cooling capacity according to current climatic conditions, and a range of relatively stable cooling capacity expended for further lowering the air temperature from a certain threshold temperature to the final outlet temperature. If a range of stable thermal load can be provided within operating a conventional compressor in a mode close to nominal, then precooling the ambient air with significant fluctuations in thermal load requires adjusting the cooling capacity by using a variable speed compressor or using the excess of heat accumulated at reduced load. Such a stage principle of cooling ensures the operation of refrigerating machines matching the behavior of current thermal loads of any air-conditioning system, whether the central air conditioning system with ambient air procession in the central air conditioner or its combination with the local indoors recirculation air conditioning systems in the air-conditioning system. in essence, as combinations of subsystems – precooling of ambient air with the regulation of cooling capacity and subsequent cooling air to the mouth of the set point temperature under relatively stable thermal load.


2021 ◽  
Vol 28 (4) ◽  
pp. 37-49
Author(s):  
Madgeed A. Al-Doury ◽  
Atif Ali Hasan ◽  
Raheem Kadhim Mohammed ◽  
Riyadh H. Al-Jawad

Thermophysical Properties of Building Materials are Considered to have high importance in predicting building thermal performance, calculating thermal loads inside building, and optimizing the use of a building and insulating materials. Due to the lack of measurements of local building materials properties, designers and air- conditioning engineers have no choice but to use the published foreign data, which probably leads to inaccurate predictions of thermal loads and may give a false thermal performance. At the same time, it leads to an over-designed capacity of air- conditioning systems that lead to increased energy consumption in the building. Thus, it is clear that it was important to conduct this research to evaluate the thermal conductivity and thermal resistance of Iraqi building materials. The number of the local building materials were listed, and specimens were collected from their sites, factories, and suppliers such as bricks, stones, concrete products, gypsum, etc. Those samples were dimensioned to the specific size required when a measurement was conducted by the Hot Wire method. All measurements were carried out at room temperature. The relationship between thermal conductivity, density, moisture content, and pressure for a number of materials was Studied. A comparison between the measurements of the Iraqi building materials and results published in the ASHRAE, CIBS Guide, Australian Specifications, and Jordanian Specifications was made. However, the availability of such data is important for the climatic design of buildings, thermal load calculations for air- conditioning, and choosing the insulating materials.


2012 ◽  
Vol 614-615 ◽  
pp. 475-479
Author(s):  
Hai Ying Wang ◽  
Chun Fang Li ◽  
Song Tao Hu ◽  
Lin Song

High-speed train air-conditioning systems put forward higher request on the aspect of air uniformity and comfort. The use of orifice which can form a more uniform velocity and temperature field in the car can be widely applied to high-speed train air-conditioning system. The experimental study of the influence of several different factors (such as the opening rate, aperture, orifice plate thickness, etc.) in the research may provide a reference for the design choices of the orifice type.


2019 ◽  
Vol 6 (3) ◽  
pp. 80-85
Author(s):  
Denis Igorevich Smagin ◽  
Konstantin Igorevich Starostin ◽  
Roman Sergeevich Savelyev ◽  
Anatoly Anatolyevich Satin ◽  
Anastasiya Romanovna Neveshkina ◽  
...  

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.


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