Construction of Linear Temperature Model using Non-dimensional Heat Exchange Ratio: towards Fast Prediction of Indoor Temperature and Heating, Ventilation and Air Conditioning Systems Control

2021 ◽  
pp. 111351
Author(s):  
Chen Ren ◽  
Shi-Jie Cao
Keyword(s):  
Heat Exchange ◽  
Air Conditioning ◽  
Temperature Model ◽  
Indoor Temperature ◽  
Linear Temperature ◽  
Systems Control ◽  
Fast Prediction ◽  
Air Conditioning Systems

DEVELOPMENT OF A METHOD FOR DETERMINING THE LENGTH TUBE EVAPORATORS AND HEAT PUMP CONDENSERS USING ZEOTROPIC MIXTURES OF WORKING AGENTS

2020 ◽  
pp. 66-77
Author(s):  
А. В. Рулев ◽  
Е. Ю. Усачева
Keyword(s):  
Heat Transfer ◽  
Heat Exchange ◽  
Heat Pump ◽  
Air Conditioning ◽  
Liquid Mixture ◽  
Transfer Processes ◽  
Temperature Conditions ◽  
Cost Efficient ◽  
Air Conditioning Systems

Постановка задачи. Необходимо разработать методику определения длины трубных испарителей и конденсаторов тепловых насосов, использующих зеотропные смеси рабочих агентов. Результаты. Приводится описание процессов теплообмена в трубных испарителях и конденсаторах тепловых насосов, использующих в качестве рабочих агентов зеотропные смеси предельных углеводородов, таких как пропан и н-бутан. Указанные смеси полностью озоно-экологически безопасны и наиболее экономичны при подогреве приточного воздуха в системах вентиляции и кондиционирования. Выводы. Разработанная методика позволяет учитывать изменение интенсивности теплообмена и температурных условий в зависимости от непрерывно изменяющихся состава и режимов течения парожидкостной смеси, протекающих в следующей последовательности: расслоенно-пробковый, кольце-волновой и дисперсный. Statement of the problem. It is essential to develop a method for determining the length of tube evaporators and heat pump condensers using zeotropic mixtures working agents. Results. The paper describes heat transfer processes in tube evaporators and heat pump condensers that use zeotropic mixtures of limiting hydrocarbons, such as propane and n-butane, as working agents. These mixtures are completely ozone-friendly and most cost-efficient when heating the supply air in ventilation and air conditioning systems. Conclusions. The developed method allows us to account for changes in the intensity of heat exchange and temperature conditions depending on the continuously changing composition and flow modes of the vapor and liquid mixture, which occur in the following sequence: stratified - cork, ring - wave and dispersed.

scholarly journals A Study on the Application Possibility of the Vehicle Air Conditioning System Using Vortex Tube

Energies ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 5227 ◽  
Author(s):  
Younghyeon Kim ◽  
Seokyeon Im ◽  
Jaeyoung Han
Keyword(s):  
Heat Exchange ◽  
Low Temperature ◽  
Flow Rate ◽  
Air Conditioning ◽  
Vortex Tube ◽  
System Simulation ◽  
Air Flow Rate ◽  
Exchange Method ◽  
Air Conditioning System ◽  
Air Conditioning Systems

Since refrigerants applied to vehicle air conditioning systems exacerbate global warming, many studies have been conducted to supplement them. However, most studies have attempted to maximize the efficiency and minimize the environmental impact of the refrigerant, and thus, an air conditioning system without refrigerant is required. The vortex tube is a temperature separation system capable of separating air at low and high temperatures using compressed air. When applied to an air conditioning system, it is possible to construct an eco-friendly system that does not use a refrigerant. In this paper, various temperature changes and characteristics of a vortex tube were identified and applied to an air conditioning system simulation device. Additionally, an air conditioning system simulation device using indirect heat exchange and direct heat exchange methods was constructed to test the low-temperature air flow rate (yc), according to the temperature and pressure. As a result of the experiment, the temperature of the indirect heat exchange method was found to be higher than the direct heat exchange method, but the direct heat exchange method had low flow resistance. As a result, the direct heat exchange method can easily control the temperature according to the pressure and the low-temperature air flow rate (yc). Therefore, it was judged that the direct heat exchange method is more feasible for use in air conditioning systems than the indirect heat exchange method.

scholarly journals Impact of Air Conditioning Systems on the Outdoor Thermal Environment during Summer in Berlin, Germany

2020 ◽  
Vol 17 (13) ◽  
pp. 4645 ◽  
Author(s):  
Luxi Jin ◽  
Sebastian Schubert ◽  
Mohamed Hefny Salim ◽  
Christoph Schneider
Keyword(s):  
Energy Consumption ◽  
Air Temperature ◽  
Air Conditioning ◽  
Waste Heat ◽  
Surface Air Temperature ◽  
Anthropogenic Heat ◽  
Reference Scenario ◽  
Indoor Temperature ◽  
Near Surface ◽  
Air Conditioning Systems

This study investigates the effect of anthropogenic heat emissions from air conditioning systems (AC) on air temperature and AC energy consumption in Berlin, Germany. We conduct simulations applying the model system CCLM/DCEP-BEM, a coupled system of the mesoscale climate model COSMO-CLM (CCLM) and the urban Double Canyon Effect Parameterization scheme with a building energy model (DCEP-BEM), for a summer period of 2018. The DCEP-BEM model is designed to explicitly compute the anthropogenic heat emissions from urban buildings and the heat flux transfer between buildings and the atmosphere. We investigate two locations where the AC outdoor units are installed: either on the wall of a building (VerAC) or on the rooftop of a building (HorAC). AC waste heat emissions considerably increase the near-surface air temperature. Compared to a reference scenario without AC systems, the VerAC scenario with a target indoor temperature of 22 ∘ C results in a temperature increase of up to 0.6 K . The increase is more pronounced during the night and for urban areas. The effect of HorAC on air temperature is overall smaller than in VerAC. With the target indoor temperature of 22 ∘ C , an urban site’s daily average AC energy consumption per floor area of a room is 9.1 W   m 2 , which is 35% more than that of a suburban site. This energy-saving results from the urban heat island effect and different building parameters between both sits. The maximum AC energy consumption occurs in the afternoon. When the target indoor temperature rises, the AC energy consumption decreases at a rate of about 16% per 2 K change in indoor temperature. The nighttime near-surface temperature in VerAC scenarios shows a declining trend ( 0.06 K per 2 K change) with increasing target indoor temperature. This feature is not obvious in HorAC scenarios which further confirms that HorAC has a smaller impact on near-surface air temperature.

Fuzzy Adaptive PID Control of Indoor Temperature in VAV System

2014 ◽  
Vol 638-640 ◽  
pp. 2092-2096 ◽  
Author(s):  
Jian Bo Bai ◽  
Yang Li ◽  
Meng Wang
Keyword(s):  
Pid Control ◽  
Air Conditioning ◽  
Large Time ◽  
Control Method ◽  
Setting Time ◽  
Control Object ◽  
Indoor Temperature ◽  
Air Conditioning Systems ◽  
Adaptive Pid Control ◽  
Fuzzy Adaptive

VAV (VAV) air-conditioning systems always have the characteristics of nonlinear, strong coupling, large time delay, thus the conventional PID control method can't meet the requirement of control performance. In order to adapt to the changes of the load in air-conditioning systems, and make an accurate rapid response, this paper proposes a fuzzy adaptive PID control method. The temperature control by terminal air valves in VAV air-conditioning systems was selected as a control object, through collecting the deviation between setting value and room temperature, the parameters of the PID controller were selected to realize the accurate control of the temperature. In order to evaluate the effectiveness of the proposed control method, it was compared with conventional PID control method by simulation experiment, the results show that the proposed Fuzzy adaptive PID control method has more shorter setting time, less overshoot and more steady state performance than the latter.

Field Test for Heat and Humidity Environment and Analysis of Air-Conditioning System Consumption

2012 ◽  
Vol 610-613 ◽  
pp. 2875-2878
Author(s):  
Hui Xing Li ◽  
Wei Xiao ◽  
Geng Geng ◽  
Bei Ni Li ◽  
Wei Wang
Keyword(s):  
Energy Consumption ◽  
Air Conditioning ◽  
Thermal Environment ◽  
Building Energy ◽  
Future Research ◽  
Main Body ◽  
Indoor Temperature ◽  
Air Conditioning System ◽  
Air Conditioning Systems ◽  
Humidity Environment

Museum has its particularity in public buildings and high research value for its thermal and humidity environment and building energy efficiency status. According to a investigation of air-conditioning systems and a test of indoor heat and humidity parameters in summer and winter for a museum in Shenyang, this article analysis its thermal environment and air-conditioning energy consumption status, draw the winter and summer indoor temperature and humidity and air-conditioning energy consumption chart, research the indoor temperature change rules and the energy consumption status of air-conditioning system in winter and summer. The results show that as air-conditioning energy consumption accounted for the main body of museum’s total building energy consumption, more energy-efficient technologies can be used to reduce the energy consumption of air-conditioning systems. And how to control the thermal environment of different types of collections in this museum, and take a consideration of energy saving, are focues of future research.

scholarly journals Cold accumulators in air conditioning systems

2019 ◽  
Vol 135 ◽  
pp. 03071
Author(s):  
Dmitriy Shlychkov
Keyword(s):  
Heat Exchange ◽  
Storage Tank ◽  
Air Conditioning ◽  
Cooling System ◽  
Energy Costs ◽  
Common Solution ◽  
Heat Exchange Surface ◽  
Air Conditioning Systems ◽  
Ice Water ◽  
Exchange Surface

The appropriateness of using cold accumulators in air conditioning systems has been assessed. A cooling system with a storage tank is considered, in which ice is frozen on the outer surface of the evaporator heat exchange tubes. It is established that the accumulation of cold can lead to a significant reduction in cash costs. The analysis of the experience of using cold accumulators in air conditioning systems allows drawing the following conclusions: the most common solution for accumulating cold is the use of ice accumulators with ice freezing on the heat exchange surface of evaporators located in the storage tank; the melting mode of ice in ice accumulators with the chiller turned off is adopted in designing. The area of the heat exchange surface of the ice accumulator apparatus during cooling of ice water should be determined mainly depending on the conditions of ice melting; to freeze ice, it is necessary to increase the heat exchange surface area of the evaporator and lower the boiling point to minus 10...15 °C. Specific energy costs (kW of electricity per kW of cold) increase by 2 or more times, which reduces profit.

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.

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