Effect of Refrigerant Charge and Inlet Air Temperature on One A/C System

This study describes the results on the performance of one vehicle air conditioning system. The coefficient of performance, evaporator cooling capacity, compressor power consumption, total mass flow rate, vapor mass flow rate, liquid mass flow rate and oil in circulation, pressures and temperatures of refrigerant at every component (inlets and outlets) are measured and analyzed with the variation of the outside temperatures at the evaporator and condenser, the speed of the compressor, refrigerant charge and oil charge. The systematical experimental results obtained from this real-size test system depict the relations between the above parameters in a vehicle air conditioning system, which constitute a useful source for vehicle air conditioning systems design and analysis. The vapor quality (two-phase flow) measurements realized in this work provide an extremely important tool for diagnosing the system performances.

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Modeling Validation and Control Analysis for Controlled Temperature and Humidity of Air Conditioning System

The Scientific World JOURNAL ◽

10.1155/2014/903032 ◽

2014 ◽

Vol 2014 ◽

pp. 1-10 ◽

Cited By ~ 2

Author(s):

Jing-Nang Lee ◽

Tsung-Min Lin ◽

Chien-Chih Chen

Keyword(s):

Mass Flow Rate ◽

Mass Flow ◽

Flow Rate ◽

Air Conditioning ◽

Thermal System ◽

Control Analysis ◽

Air Conditioning System ◽

Temperature And Humidity ◽

Control Criteria ◽

And Control

This study constructs an energy based model of thermal system for controlled temperature and humidity air conditioning system, and introduces the influence of the mass flow rate, heater and humidifier for proposed control criteria to achieve the controlled temperature and humidity of air conditioning system. Then, the reliability of proposed thermal system model is established by both MATLAB dynamic simulation and the literature validation. Finally, the PID control strategy is applied for controlling the air mass flow rate, humidifying capacity, and heating, capacity. The simulation results show that the temperature and humidity are stable at 541 sec, the disturbance of temperature is only 0.14°C, 0006 kgw/kgdain steady-state error of humidity ratio, and the error rate is only 7.5%. The results prove that the proposed system is an effective controlled temperature and humidity of an air conditioning system.

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Experimental Analysis on the Performance of Regeneration of Solar Liquid Desiccant System under Different Operation Condition

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.521.48 ◽

2014 ◽

Vol 521 ◽

pp. 48-51

Author(s):

Sun Jian

Keyword(s):

Mass Flow Rate ◽

Mass Flow ◽

Flow Rate ◽

Air Conditioning ◽

Liquid Desiccant ◽

Operation Condition ◽

Air Conditioning System ◽

Thermally Driven ◽

Diluted Solution ◽

Set Up

Liquid desiccant air-conditioning system is one kind of thermally driven open-cycle absorption air-conditioning systems which have been widely researched and applied because of its unique advantages in recent years.In this paper, an experimental equipment of liquid desiccant air-conditioning system was set up based on the mechanism of liquid desiccant dehumidification and regeneration. The dehumidifier and regenerator were all counter-flow towers and body of the tower were made of stainless steel to withstand the corrosive effect of the liquid desiccant. In experiments, mixture desiccant of calcium chloride and lithium chloride was applied.The performance of regeneration of the system was studied under different system operating condition. The effects of the inlet parameters on the efficiency of regeneration are discussed. The results show that the mass flow rate,humidity of the air,temperature and mass flow rate of the diluted solution can all affect the performance of regeneration of the system.

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Swirl–nozzle interaction experiment: quasi-steady model-based analysis

Experiments in Fluids ◽

10.1007/s00348-021-03271-y ◽

2021 ◽

Vol 62 (8) ◽

Author(s):

Lionel Hirschberg ◽

Friedrich Bake ◽

Karsten Knobloch ◽

Angelo Rudolphi ◽

Sebastian Kruck ◽

...

Keyword(s):

Mass Flow Rate ◽

Mass Flow ◽

Flow Rate ◽

Acoustic Pressure ◽

Quantitative Information ◽

Acoustic Response ◽

Flow Measurements ◽

Flow Rate Change ◽

Interaction Experiment ◽

Swirl Stabilized Combustion

AbstractMeasurements of sound due to swirl–nozzle interaction are presented. In the experiment a swirl structure was generated by means of unsteady tangential injection into a steady swirl-free flow upstream from a choked convergent–divergent nozzle. Ingestion of swirl by the choked nozzle caused a mass-flow rate change, which resulted in a downstream-measured acoustic response. The downstream acoustic pressure was found to remain negative as long as the swirl is maintained and reflections from the open downstream pipe termination do not interfere. The amplitude of this initial acoustic response was found to be proportional to the square of the tangential mass-flow rate used to generate swirl. When the tangential injection valve was closed, the mass-flow rate through the nozzle increased, resulting in an increase of the downstream acoustic pressure. This increase in signal was compared to the prediction of an empirical quasi-steady model, constructed from steady-state flow measurements. As the opening time of the valve was varied, the signal due to swirl evacuation showed an initial overshoot with respect to quasi-steady behavior, after which it gradually decayed to quasi-steady behavior for tangential injection times long compared to the convection time in the pipe upstream of the nozzle. This demonstrates that the acoustic signal can be used to obtain quantitative information concerning the time dependence of the swirl in the system. This could be useful for understanding the dynamics of flow in engines with swirl-stabilized combustion. Graphic abstract

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Thermal Characterization of Interlayer Microfluidic Cooling of Three-Dimensional Integrated Circuits With Nonuniform Heat Flux

Journal of Heat Transfer ◽

10.1115/1.4000885 ◽

2010 ◽

Vol 132 (4) ◽

Cited By ~ 64

Author(s):

Yoon Jo Kim ◽

Yogendra K. Joshi ◽

Andrei G. Fedorov ◽

Young-Joon Lee ◽

Sung-Kyu Lim

Keyword(s):

Integrated Circuits ◽

Mass Flow Rate ◽

Thermal Management ◽

Mass Flow ◽

Flow Rate ◽

Single Phase ◽

Hot Spot ◽

Three Dimensional ◽

Two Phase ◽

Two Phase Cooling

It is now widely recognized that the three-dimensional (3D) system integration is a key enabling technology to achieve the performance needs of future microprocessor integrated circuits (ICs). To provide modular thermal management in 3D-stacked ICs, the interlayer microfluidic cooling scheme is adopted and analyzed in this study focusing on a single cooling layer performance. The effects of cooling mode (single-phase versus phase-change) and stack/layer geometry on thermal management performance are quantitatively analyzed, and implications on the through-silicon-via scaling and electrical interconnect congestion are discussed. Also, the thermal and hydraulic performance of several two-phase refrigerants is discussed in comparison with single-phase cooling. The results show that the large internal pressure and the pumping pressure drop are significant limiting factors, along with significant mass flow rate maldistribution due to the presence of hot-spots. Nevertheless, two-phase cooling using R123 and R245ca refrigerants yields superior performance to single-phase cooling for the hot-spot fluxes approaching ∼300 W/cm2. In general, a hybrid cooling scheme with a dedicated approach to the hot-spot thermal management should greatly improve the two-phase cooling system performance and reliability by enabling a cooling-load-matched thermal design and by suppressing the mass flow rate maldistribution within the cooling layer.

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Experimental Investigation on Flow Characteristic of Stepped Capillary Tube for Heat Pump Type Air Conditioner with R410A

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.960-961.643 ◽

2014 ◽

Vol 960-961 ◽

pp. 643-647

Author(s):

Yan Sheng Xu

Keyword(s):

Mass Flow Rate ◽

Heat Pump ◽

Mass Flow ◽

Flow Rate ◽

Capillary Tube ◽

Coefficient Of Performance ◽

Tube Length ◽

Air Conditioner ◽

Capillary Tubes ◽

Tube Assembly

A stepped capillary tube consisting of two serially connected capillary tubes with different diameters is invented to replace the conventional expansion device. The mass flow rate of refrigerant R410A in stepped capillary tubes with different size were tested. The model of stepped capillary tube is proposed, and its numerical algorithm for tube length and mass flow rate is developed. The experimental results show that the performance comparing between stepped capillary tube system and capillary tube assembly system, the cooling capacity is reduced by 0.3%, the energy efficiency ratio (EER) is equal to each other, the heating capacity is increased by 0.3%, the coefficient of performance (COP) is decreased by 0.3%. That is to say, the performance index of the two kinds of throttle mechanism is almost identical. It indicates that the stepped capillary tube can replace the capillary tube assembly in the R410A heat pump type air conditioner absolutely. The model is validated with experimental data, and the results show that the model can be used for sizing and rating stepped capillary tube.

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Development of Hybrid Airlift-Jet Pump with Its Performance Analysis

Applied Sciences ◽

10.3390/app8091413 ◽

2018 ◽

Vol 8 (9) ◽

pp. 1413 ◽

Cited By ~ 2

Author(s):

Dan Yao ◽

Kwongi Lee ◽

Minho Ha ◽

Cheolung Cheong ◽

Inhiug Lee

Keyword(s):

Boundary Conditions ◽

Mass Flow Rate ◽

Mass Flow ◽

Flow Rate ◽

Stokes Equations ◽

Flow Characteristics ◽

Operating Conditions ◽

Navier Stokes ◽

Jet Pump ◽

Two Phase

A new pump, called the hybrid airlift-jet pump, is developed by reinforcing the advantages and minimizing the demerits of airlift and jet pumps. First, a basic design of the hybrid airlift-jet pump is schematically presented. Subsequently, its performance characteristics are numerically investigated by varying the operating conditions of the airlift and jet parts in the hybrid pump. The compressible unsteady Reynolds-averaged Navier-Stokes equations, combined with the homogeneous mixture model for multiphase flow, are used as the governing equations for the two-phase flow in the hybrid pump. The pressure-based methods combined with the Pressure-Implicit with Splitting of Operators (PISO) algorithm are used as the computational fluid dynamics techniques. The validity of the present numerical methods is confirmed by comparing the predicted mass flow rate with the measured ones. In total, 18 simulation cases that are designed to represent the various operating conditions of the hybrid pump are investigated: eight of these cases belong to the operating conditions of only the jet part with different air and water inlet boundary conditions, and the remaining ten cases belong to the operating conditions of both the airlift and jet parts with different air and water inlet boundary conditions. The mass flow rate and the efficiency are compared for each case. For further investigation into the detailed flow characteristics, the pressure and velocity distributions of the mixture in a primary pipe are compared. Furthermore, a periodic fluctuation of the water flow in the mass flow rate is found and analyzed. Our results show that the performance of the jet or airlift pump can be enhanced by combining the operating principles of two pumps into the hybrid airlift-jet pump, newly proposed in the present study.

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Research on Two-Phase Flow Instability in Evaporator of Refrigeration System

ASME 2010 3rd Joint US-European Fluids Engineering Summer Meeting: Volume 1, Symposia – Parts A, B, and C ◽

10.1115/fedsm-icnmm2010-30487 ◽

2010 ◽

Author(s):

Nan Liang ◽

Changqing Tian ◽

Shuangquan Shao

Keyword(s):

Pressure Drop ◽

Mass Flow Rate ◽

Mass Flow ◽

Flow Rate ◽

Two Phase Flow ◽

Density Wave ◽

Phase Flow ◽

Constant Mass ◽

Refrigeration System ◽

Two Phase

As one kind of fluid machinery related to the two-phase flow, the refrigeration system encounters more problems of instability. It is essential to ensure the stability of the refrigeration systems for the operation and efficiency. This paper presents the experimental investigation on the static and dynamic instability in an evaporator of refrigeration system. The static instability experiments showed that the oscillatory period and swing of the mixture-vapor transition point by observation with a camera through the transparent quartz glass tube at the outlet of the evaporator. The pressure drop versus mass flow rate curves of refrigerant two phase flow in the evaporator were obtained with a negative slope region in addition to two positive slope regions, thus making the flow rate a multi-valued function of the pressure drop. For dynamic instabilities in the evaporation process, three types of oscillations (density wave type, pressure drop type and thermal type) were observed at different mass flow rates and heat fluxes, which can be represented in the pressure drop versus mass flow rate curves. For the dynamic instabilities, density wave oscillations happen when the heat flux is high with the constant mass flow rate. Thermal oscillations happen when the heat flux is correspondingly low with constant mass flow rate. Though the refrigeration system do not have special tank, the accumulator and receiver provide enough compressible volume to induce the pressure drop oscillations. The representation and characteristic of each oscillation type were also analyzed in the paper.

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