Automobile Air Conditioning Research Articles

TFA from HFO‐1234yf: Accumulation and aquatic risk in terminal water bodies

A next-generation mobile automobile air-conditioning (MAC) refrigerant, HFO-1234yf (CF(3) CF = CH(2)), is being developed with improved environmental characteristics. In the atmosphere, it ultimately forms trifluoroacetic acid (TFA(A); CF(3)COOH), which is subsequently scavenged by precipitation and deposited on land and water as trifluoroacetate (TFA; CF(3)COO(-)). Trifluoroacetate is environmentally stable and has the potential to accumulate in terminal water bodies, that is, aquatic systems receiving inflow but with little or no outflow and with high rates of evaporation. Previous studies have estimated the emission rates of HFO-1234yf and have modeled the deposition concentrations and rates of TFA across North America. The present study uses multimedia modeling and geographic information system (GIS)-based modeling to assess the potential concentrations of TFA in terminal water bodies over extended periods. After 10 years of emissions, predicted concentrations of TFA in terminal water bodies across North America are estimated to range between current background levels (i.e., 0.01-0.22 µg/L) and 1 to 6 µg/L. After 50 years of continuous emissions, aquatic concentrations of 1 to 15 µg/L are predicted, with extreme concentrations of up to 50 to 200 µg/L in settings such as the Sonoran Desert along the California/Arizona (USA) border. Based on the relative insensitivity of aquatic organisms to TFA, predicted concentrations of TFA in terminal water bodies are not expected to impair aquatic systems, even considering potential emissions over extended periods.

The Research on the Surface Temperature Field of the Gas Cooler in the Microchannel

Empirical studies on the heat exchange characteristic of the span borderline CO2 of the parallel flow gas cooler in the hol-aluminium microchannel and the surface temperature distribution of the gas cooler during heat exchanging of the span borderline CO2. Through experiments we got the surface temperature distribution of the cooler in the wind. These studies provide evidences for the design of the hol-aluminium mirochannel parallel flow gas cooler in the carbon dioxide automobile air conditioning system.

Airside Pressure Drop Mechanism of Automobile Air-Conditioner Evaporator Plating with Hydrophilic Film

A mathematical model of airside pressure drop was established, and calculations were conducted respectively under dry condition and wet condition for evaporators with hydrophilic treatment and without hydrophilic treatment. Experimental results demonstrate the proposed model. The results reveal a significant improvement of hydrophilic treatment, and air resistance drops to 53% when relative humidity is 50%, while it drops to 50% when relative humidity is 90%.

Experimental Study of an Internal Heat Exchanger Influence on R134a Automobile Air Conditioning System

Liquid-suction or internal heat exchanger (IHX) is installed in vapor compression refrigeration systems to exchange energy between cool low-pressure gas and warm high-pressure liquid refrigerant. The aim of this research is to experimentally evaluate the effect of IHX adaptation in an automotive air conditioning system focusing on evaporator working conditions. In this new design of IHX, the high-pressure liquid passes through the central channel and the low-pressure vapor flows in several parallel channels in the opposite direction. The experimental set-up has been made up of original components of the air conditioning system of a medium sedan car, specially designed and built to analyze vehicle A/C equipments under real work conditions. The results show that low pressure drop will be imposed on the cycle using this type of IHX. Also, they confirm considerable decrease of compressor power consumption; it is intensified at higher evaporator air flow. A significant improvement of the coefficient of performance will be achieved with IHX too. The influence of operating conditions has been also discussed in this paper.

Performance Evaluation of an Automobile Air Conditioning System Using R134a

In this paper, a detailed energy and exergy analysis have been dealt with on experimental AAC (Automobile Air Conditioning) system with R134a as working refrigerant. For this aim, an experimental AAC system consisting of a laminated type evaporator, swash plate type compressor, a parallel flow type condenser, TXV(thermostatic expansion valve) and a receiver drier. The performance analysis of separate components of AAC system has been carried out under various compressor speeds and thermal loads. AAC system equipped with increasing compressor speed by three-phase electric motor controlled by frequency converter. Various thermal loads in the range of 1500 and 2850 W were applied to the system by means of electric heaters. The experiments were conducted at the condensing temperatures of 50-60 oC for each thermal load, and at the compressor speeds of 600, 800, 1000, 1200, 1400 rpm for each thermal load-condensing temperature combination. The refrigerant and air temperatures, refrigerant pressures, compressor speed, air velocity passing through the evaporator and thermal load were measured. Effects on system performance of such operational parameters as compressor speed, return air in the evaporator and condensing air temperatures have been experimentally evaluated and by means of energy and exergy analysis.

Using “Smart Stimulators” to Treat Parkinson’s Disease: Re-Engineering Neurostimulation Devices

Let’s imagine the cruise control of your car locked at 120 km/h on any road in any condition (city, country, highway, sunny or rainy weather), or your car air conditioner set on maximum cold in any temperature condition (even during a snowy winter): would you find it efficient? That would probably not be the most optimal strategy for a proper and comfortable driving experience. As surprising as this may seem, this is a pretty accurate illustration of how deep brain stimulation is used today to treat Parkinson’s disease motor symptoms and other neurological disorders such as essential tremor, obsessive-compulsive disorder, or epilepsy.

Measures against global warming and assessments of environmental impact for fluorinated carbon materials

Global warming countermeasures have been evaluated using the global warming potential (GWP). However, since GWP shows only one aspect of global warming, the alternative indicator, carbon dioxide equivalent warming number (CEWN), which is based on the removal rate of each greenhouse gas from the atmosphere, is explained here. The latest CEWN values are shown, and the life cycle climate performance results of car air-conditioning, recovery and recycling of R-22 refrigerant and semiconductor cleaning process, where fluorinated carbon compounds are used, are evaluated with those CEWN values. The results reveal that fluorinated carbon compounds are beneficial in coping with global warming. In addition, carbon resources are also evaluated with new concept, and consequently it is shown that fluorinated carbon compounds are beneficial in conserving carbon resources.

냉매 내 수분의 혼입량이 차량 에어컨의 냉각성능에 미치는 영향

This study was conducted to figure out the diagnosis basis of cooling performance depending on water amount in the refrigerant of air conditioner, which can be estimated by the temperatures and pressures along the refrigerant circulation line. A car air conditioner of SONATA III (Hyundai motor Co., Korea) was tested at maximum cooling condition at the engine speed of 1500 rpm in the room controlled at 33~<TEX>$35^{\circ}C$</TEX> air temperature and 55~57% relative humidity conditionally. Measured variables were temperature differences between inlet and outlet pipe surfaces of the compressor, condenser, receive drier and evaporator; and high pressure and low pressure in the refrigerant circulation line; and temperature difference between inlet and outlet air of the cooling vent of evaporator. In this study, changes of the water amount in the refrigerant were correlated to the temperatures and pressure changes and also water amount caused poor cooling performance. As water amount increased in the refrigerant in the air conditioner, the performance of the cooling or the heat transfer became worse. Temporal variations of the surface temperature of the evaporator outlet pipe and the low-side pressure showed various patterns that could estimate the water amount. When the water amount caused bad cooling performance, the patterns of the temperature of the evaporator outlet pipe indicated irregular fluctuation greater than <TEX>$5^{\circ}C$</TEX>. When the diagnosis system is using just external sensors of the low-side pressure and the temperatures of inlet and outlet air of cooling vent of the evaporator, the precise pattern of bad cooling performance caused by excess water amount in the cooling line was irregular pressure fluctuation, 25 kPa under 120 kPa, and temperature, <TEX>$12^{\circ}C$</TEX> and less.

Modeling of temperature and humidity ratio in an automobile passenger compartment for automobile air conditioning systems

This study investigates thermal dynamic modeling of a passenger compartment in an air conditioned automobile equipped with HVAC (heating, ventilation, and air conditioning). In particular, dynamics of temperature and humidity ratio, both critical to passenger comfort, in the passenger compartment are examined. By analyzing enthalpy change during an automobile air conditioning circulation cycle on a psychrometric chart, heat exchange between outside environment and the passenger compartment can be modeled as functions of operation settings of the HVAC. With enthalpy content decomposed into sensible heat and latent heat, changes in heat content can be attributed to the changes in the corresponding temperature and humidity ratio, respectively. Consequently, impacts resulting from the mismatch between two heat characteristics on temperature and humidity ratio can be formulated accordingly: room sensible heat factor (RSHF) of the passenger compartment and apparatus sensible heat factor (ASHF) of the HVAC. A Matlab/Simulink simulation is implemented to verify the proposed model under several control policies that either maintain constant enthalpy or maintain constant temperature in the passenger compartment. With these two temperature and humidity ratio models derived, further research on designing control policies to achieve better passenger comfort for general automobile air conditioning systems can be derived and tested.

A study on integrated design conjugation profiles application analysis of scroll profiles for automobile air conditioning

The research on scroll profiles theory at present mainly is aiming at the single profile and its amelioration or parameter optimization, not aiming at the natural characteristic of the profiles equation of scroll profiles itself. Thus, the intrinsic differential equation bearing on arc-length and tangent direction angle was studied. Using the inherent differential equation and general functional theory, the conversion ideas between the expression of intrinsic differential equation and the expression in Cartesian coordinate was studied, and the condition of involutes characteristic was presented. The detailed analysis of four typical scroll profiles was given. According to the four typical scroll profiles and based on the method of Taylor series, the unified formation of general functional integration scroll profiles was established, which perfected general theory of scroll profiles increasingly. The envelope method to seek conjugation engagement profiles was studied. The unified general functional equation of scroll profiles represented the admissible function scrolls and the conjugation engagement characteristic of which was studied. The engagement condition of conjugation scroll profiles and the expression in Cartesian coordinate of conjugation scroll profiles of general functional integration scroll profiles were educed. Therefore, the restriction of inherent characteristics of single scroll profiles model is broken through. Solid modeling and machine tool path simulation can bridge the gap between design and manufacture which is essential for the design and manufacture of scroll compressors. With this method a perfect solid model can be achieved, which leads to an optimal design in terms of quality, delivery time and cost. The presentation of unified formation of general functional integration scroll profiles represents foundation factor of instinct characteristics of scroll profiles, which widens the design method of scroll compressor for automobile air conditioning.

Development and lab-test of a mobile adsorption air-conditioner

This paper is focused on the description of a mobile adsorption chiller for cooling in a truck cabin and its experimental performance. The prototype, designed and built at CNR – ITAE, consists of a double-bed adsorber connected with an evaporator and a condenser and driven by the low grade thermal energy coming from the engine coolant loop. Overall volume and weight of the machine are 170 dm3 and 60 kg, respectively. Performance assessment was preliminarily carried out at ITAE laboratory under the typical EU car air conditioning conditions. The experimental results obtained showed that the system is able to deliver an Average Cooling Power ACP = 1–2.3 kW and a Cooling COP = 0.25–0.45, at a desorption temperature of about 90 °C (Tev ∼ 8–14 °C and Tcon ∼ 28–35 °C). Afterwards, the cooling system was integrated in a real truck cabin (IVECO STRALIS) and tested on a laboratory test bench, where the engine cooling loop was simulated through an ideal heat source, so demonstrating that the chiller is able to provide cooling comfort to the passengers.

Improvement of Torsional Fretting Fatigue Strength of Splined Shaft Used for Car Air Conditioner's Compressor by Hybrid Joint

To improve the fretting fatigue strength of splined shaft used for compressor of car air conditioner, press-fit joint was combined with the spline joint. Torsional fretting fatigue strength of the combined jointed shaft was evaluated focusing on the effect of press-fit interference which must be secured when the combined joint is applied to the production process. Torsional fretting fatigue strength of the splined shaft was drastically increased by the combination of press-fit. The improvement was achieved by sharing transmitted torque between press-fit and spline. While fretting fatigue failure occurred at the press-fitted part when the press-fit interference was relatively small, the combined jointed shaft had four times higher fatigue strength than the conventional splined shaft. The increase of press-fit interference prevented the fretting fatigue failure and brought further increase of the fatigue strength, since amount of relative slip was significantly reduced by the increase of contact pressure.

Performance and Evaluation of Aqua Ammonia Auto Air Conditioner System Using Exhaust Waste Energy

Abstract This work presents an experimental study of an aqua-ammonia absorption system used for automobile air conditioning system, this system using the exhaust waste heat of an internal combustion diesel engine as energy source. The energy availability that can be used in the generator and the effect of the system on engine performance, exhaust emissions, auto air conditioning performance and fuel economy are evaluated. Because automotive air conditioning is one the most equipment that heavily uses CFC compounds and the leakage of CFCs from such air conditioners impact on the environment. The main purpose of this investigation to explore the feasibility of using waste energy to design the absorber and generation since these components are the most important components of absorption and they are directly influence the performance of the whole system. It has been found that the aqua -ammonia concentration effect the cooling capacity. The estimated cooling load for the automobile found to be within acceptable ranges which are about 1.37 ton refrigeration. The obtained results show that the coefficient of performance (COP) values directly proportional with increasing generator and evaporator temperatures but decrease with increasing condenser and absorber temperatures. Measured values for generator, absorber, and evaporator and condenser temperature were recorded and the coefficient of performance of the system varied between 0.85 and 1.04. The main components of the absorption cycle were designed and fabricated for optimal performance and could be rapidly transfer to the industry, The system was found to be applicable and ready to produce the required conditioning effect without any additional load to the engine. The proposed system decreases vehicle operating costs and environmental pollution caused by the heating system as well as causing a lower global warming.

Improvement of Torsional Fretting Fatigue Strength of Splined Shaft Used for Car Air Conditioning Compressors by Hybrid Joint

To improve the fatigue strength of the splined shaft used for a car's air conditioning compressor, press fit was added to the innermost part of the spline. This shaft connection consisting of a spline and press fit is called a in this study. A torsional fretting fatigue test was performed focusing on the effect of the amount of interference on the fatigue strength. The fatigue strength of the splined shaft was drastically increased by the hybrid joint. The fatigue strength of the hybrid joint was at most 8 times higher than that of the conventional spline-joint shaft. The fatigue strength as well as the failure mode of the hybrid-jointed specimens were changed depending on the amount of interference. The reason was that the relative slip was significantly reduced with an increase in the amount of interference. The specimen consisted of a shaft, a boss and a bolt. The hybrid joint prevented loosening of the bolt, while loosening of the bolt was found to occur in the conventional spline-joint shaft.

Construction of Dynamical Model of Thermal Environment and Thermal Comfort to Design Automobile Air-conditioning System

Construction of Dynamical Model of Thermal Environment and Thermal Comfort to Design Automobile Air-conditioning System

Measures against global warming and assessments of environmental impact for fluorinated carbon materials

Global warming countermeasures have been evaluated using the global warming potential (GWP). However, since GWP shows only one aspect of global warming, the alternative indicator, carbon dioxide equivalent warming number (CEWN), which is based on the removal rate of each greenhouse gas from the atmosphere, is explained here. The latest CEWN values are shown, and the life cycle climate performance results of car air-conditioning, recovery and recycling of R-22 refrigerant and semiconductor cleaning process, where fluorinated carbon compounds are used, are evaluated with those CEWN values. The results reveal that fluorinated carbon compounds are beneficial in coping with global warming. In addition, carbon resources are also evaluated with new concept, and consequently it is shown that fluorinated carbon compounds are beneficial in conserving carbon resources.

Modeling and multi-objective optimization of parallel flow condenser using evolutionary algorithm

Parallel flow condenser (PFC), which is widely used in automobile air conditioning (AAC) industries, was modeled and optimized in this paper. A sample of designed and manufactured condenser of this type was modeled and tested. In the proposed physical model the condenser is divided into three regions of superheat, saturated (two-phase) and subcooled. The modeling results validated by comparison with the experimental data. In optimization section, the condenser heat transfer rate was maximized while its pressure drop was minimized applying genetic algorithm multi-objective optimization technique. A set of Pareto optimal solutions as well as the final optimal design point were presented for our case study. The optimum design parameters resulted in heat transfer rate increase for 7.1% and decrease in pressure drop for 96% in comparison with the corresponding manufactured operating parameters.

Design and Fabrication of Auto Air Conditioner Generator Utilizing Exhaust Waste Energy from a Diesel Engine

In this investigation; analysis and design of an automobile air conditioner was made by utilizing the available diesel engine exhaust waste energy to provide the required heat for the generator. Because automotive air conditioning is one of the most equipment that heavily uses CFC compounds, and the leakage of CFCs from such air conditioners affect the environment, the absorption cycle was found to be an ideal option. Cooling load for the automobile has been estimated and found to be within acceptable ranges which are about 1.37 TR. The reported results show that the COP values directly proportional with increasing generator and evaporator temperatures. Measured COP values of the proposed model varied between 0.85 and 1.04. The generator was designed and fabricated for optimal performance and could be rapidly transfer to the industrial applications, The system was found to be applicable and ready to produce the required conditioning effect without any additional load to the engine The proposed system decreases vehicle operating costs and environmental pollution caused by the heating system as well as causing a lower global warming. Simple experiments were carried out to examine the performance of the generator heat shown the benefit of exhaust gases as an alternative heating source.

Numerical Model of the Temperature Control Curve Linearity of HVAC Module in Automobile Air-Conditioning System and Applications

In the present work, a numerical model of the temperature control curve (TCC) linearity of the heating ventilating and air conditioning (HVAC) module in automobile air-conditioning system is established. The numerical model is composed of several higher precision submodels. The simulation results are validated by experimental data performed on a calorimeter test bench. It is found that the simulation data agree with the experimental data very well. The maximum deviations of the airflow rate and the temperature are 3% and 1.4°C, respectively. The factors, which influenced the TCC linearity, are numerically studied. The simulation results show that the different door configuration needs to be matched with the division type for vent ducts of the HVAC module outlet, which can decrease the temperature stratification of airflow at the outlets. Cold and hot air mixing ratio determines the slope of the linearity curve. In addition, the further the distance between the HVAC module outlet and the mixing chamber and the greater the turbulent intensity, the more the cold-hot airflow will fully mix. It contributes to the temperature uniformity at the outlets.

Thermal analysis of car air conditioning

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.