Air Mix versus Coolant Flow to Control Discharge Air Temperature in Vehicle Heating and Air Conditioning Systems

1993 ◽  
Author(s):  
Gary M. Rolling ◽  
Robert W. Cummings ◽  
Gebhard Schweizer
Keyword(s):  
Air Temperature ◽  
Air Conditioning ◽  
Coolant Flow ◽  
Control Discharge ◽  
Air Conditioning Systems

Experimental investigations on the performance of solar powered cabin air ventilator

2015 ◽  
Vol 12 (6) ◽  
pp. 607-618 ◽  
Author(s):  
Sudhir Chitrapady Vishweshwara ◽  
Jalal Marhoon AL. Dhali
Keyword(s):  
Thermal Comfort ◽  
Air Temperature ◽  
Air Conditioning ◽  
Temperature Drop ◽  
Ambient Air ◽  
Comfort Level ◽  
Cabin Temperature ◽  
Solar Powered ◽  
Air Conditioning Systems ◽  
Air Exchange

Sultanate of Oman witness a long summer with mostly clear blue skies and typically higher ambient temperatures as seen in other GCC countries. This type of environment warrants the use of high capacity and reliable air conditioning systems, both at resident buildings and vehicles. During summer, cars parked directly under the sun, experience a very high temperature rise inside its cabin in the range of near to 50 °C. This high cabin air temperature often causes thermal discomfort to passengers entering the parked car and also has a serious impact on the cars air-conditioning systems, as it takes longer time to bring back the thermal comfort inside the cabin. The studies also revealed that the high cabin temperature often causes health hazards to occupants, especially to infants. Current research paper, reports an experimental study carried out on a parked car, with instrumentation to identify the various the temperature zones inside the car cabin. This experiential study is aimed to improve the thermal comfort inside the cabin through solar powered cabin air ventilator for effective management of cabin air temperature. The study was carried on a chosen vehicle parked at a set direction and location exposed to day long sunlight at Muscat for considerable period of time. Firstly, the study identified the various temperature zones inside the car cabin and ventilation driven with a 10 Wp solar panel was developed to accomplish the required air exchange inside the cabin, along with continues instantaneous heat rejection through steady air exchange between inside and outside environment. A simple ventilator was developed by means of two fans which drove out the hot trapped air and a secondary fan to cool down the temperature inside the car by providing fresh air for limited time. The experimental investigation showed that the vehicle cabin temperature was typically 10 °C lower when ventilator was turned on. On a typical day on month of May, the cabin air temperatures was approximately 21 °C higher than the ambient air temperature, while with the developed ventilator the difference between the cabin and outside air temperature was reduced by 50% approximately. With the ventilator in operation, it was observed that time taken to reduce the cabin air temperature through vehicle air conditioning system to a satisfactory level was much quicker; typically it took less than the half of the time compared to those values tested without ventilator. Thus indicating, the power saving potential of the developed system as the desired level of thermal comfort can be achieved within the shorter period of time. The reduction in time taken to cool down the cabin temperature to the acceptable limits has direct two fold effects; firstly, the fuel consumption for cooling purpose is reduced and secondly, increased thermal comfort level inside the cars cabin. However, the temperature drop pattern was not similar all around the cabin, due to the varied level of cabin sunlight exposure. Temperature drop at the front of the car was lower than in middle and rear of the car. From the study it can be concluded that, with solar powered ventilator, the temperature inside the car was nearly 10 °C lesser compared to cabin without ventilator and it also helps in to bring back the thermal comfort inside the cabin nearly within half time vis-à-vis cabin without ventilation.

Uncertainty shift in robust predictive control design for application in CAV air-conditioning systems

2011 ◽  
Vol 32 (4) ◽  
pp. 329-343 ◽  
Author(s):  
Gongsheng Huang ◽  
Tin-Tai Chow
Keyword(s):  
Air Temperature ◽  
Predictive Control ◽  
Air Conditioning ◽  
Prediction Models ◽  
Control Design ◽  
Pi Control ◽  
Control Law ◽  
Original Design ◽  
Input Structure ◽  
Air Conditioning Systems

Constant-air-volume (CAV) air-conditioning systems consist mainly of two local processes: an air-handling process and a room temperature process. A robust model predictive control (RMPC) strategy was developed for CAV air-conditioning systems, which adopted two uncertain first-order plus time-delay models to describe the dynamics of the local processes and used a linear matrix inequality (LMI)-based optimisation technique to optimise the control law. This paper develops a new control design, which reformulates the prediction models by shifting the uncertainties of the first model into the second one, and then uses the reformulated prediction models in the RMPC strategy. This paper will show that compared with the original design, the new control design can enhance the feasibility of the optimisation of control law, reduce the computational burden of the optimisation and also remove the requirement of a sensor for supply air temperature in the original design. Practical applications: The new design method is a further development of a RMPC strategy presented in Xu et al.13 It inherits the benefits of the original control design for practical application, i.e. uncertainties and constraints can be dealt with simultaneously in the design and the robustness of the controlled system can be enhanced. The new design improves the optimisation feasibility, reduces the computational complexity and does not need to measure the supply air temperature. When the new design is adopted to replace the traditional PI control, there is no necessity to change the existent input structure of the PI control. Hence, the new design can be realised in practice easier than the original design.

scholarly journals Thermal analysis of car air conditioning

2010 ◽  
Vol 31 (4) ◽  
pp. 71-80 ◽  
Author(s):  
Daniel Trzebiński ◽  
Ireneusz Szczygieł
Keyword(s):  
Thermal Analysis ◽  
Thermodynamic Analysis ◽  
Air Temperature ◽  
Air Conditioning ◽  
Expansion Valve ◽  
Air Cooler ◽  
Air Conditioning Systems ◽  
The Impact

Thermal analysis of car air conditioningThermodynamic analysis of car air cooler is presented in this paper. Typical refrigerator cycles are studied. The first: with uncontrolled orifice and non controlled compressor and the second one with the thermostatic controlled expansion valve and externally controlled compressor. The influence of the refrigerant decrease and the change of the air temperature which gets to exchangers on the refrigeration efficiency of the system; was analysed. Also, its effectiveness and the power required to drive the compressor were investigated. The impact of improper refrigerant charge on the performance of air conditioning systems was also checked.

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.

scholarly journals Performance Analysis of Data–Driven and Model–Based Control Strategies Applied to a Thermal Unit Model

2016 ◽  
Author(s):  
Cihan Turhan ◽  
Silvio Simani ◽  
Ivan Zajic ◽  
Gulden Gokcen Akkurt
Keyword(s):  
Air Temperature ◽  
Measurement Errors ◽  
Air Conditioning ◽  
Control Strategies ◽  
External Disturbance ◽  
Thermal Unit ◽  
Time Model ◽  
Control Schemes ◽  
Advanced Control ◽  
Air Conditioning Systems

The paper presents the design and the implementation of different advanced control strategies that are applied to a nonlinear model of a thermal unit. A data–driven grey–box identification approach provided the physically meaningful nonlinear continuous–time model, which represents the benchmark exploited in this work. The control problem of this thermal unit is important since it constitutes the key element of passive air conditioning systems. The advanced control schemes analysed in this paper are used to regulate the outflow air temperature of the thermal unit by exploiting the inflow air speed, whilst the inflow air temperature is considered as an external disturbance. The reliability and robustness issues of the suggested control methodologies are verified with a Monte–Carlo analysis for simulating modelling uncertainty, disturbance and measurement errors. The achieved results serve to demonstrate the effectiveness and the viable application the suggested control solutions to air conditioning systems. The benchmark model represents one of the key issues of this study, which is exploited for benchmarking different model–based and data–driven advanced control methodologies through extensive simulations. Moreover, this work highlights the main features of the proposed control schemes, while providing practitioners and heating, ventilating and air conditioning engineers with tools to design robust control strategies for air conditioning systems.

Experimental evaluation of refrigerant mass charge and ambient air temperature effects on performance of air-conditioning systems

2017 ◽  
Vol 54 (3) ◽  
pp. 803-812 ◽  
Author(s):  
Mahdi Deymi-Dashtebayaz ◽  
Mehdi Farahnak ◽  
Mojtaba Moraffa ◽  
Arash Ghalami ◽  
Nima Mohammadi
Keyword(s):  
Air Temperature ◽  
Experimental Evaluation ◽  
Temperature Effects ◽  
Air Conditioning ◽  
Ambient Air ◽  
Ambient Air Temperature ◽  
Air Conditioning Systems

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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