Environment friendly refrigerant options for automobile air conditioners: a review

Potential reduction in emissions after replacement of automobile air conditioning refrigerants in China

The refrigerant R134a is to be phasing out soon in automobile air conditioning applications due to its high global warming potential of 1430. Hence, it is essential to identify a sustainable alternative refrigerant to phase out R134a in automobile air conditioners. This paper presents the experimental thermodynamic performance of R430A (composed of R152a and R600a, in the ratio of 76:24, by mass) as a drop-in substitute to replace R134a in automobile air conditioners. The experiments were carried out in an automobile air conditioner test setup equipped with a variable frequency drive electrical motor. During experimentation, the ambient temperature and ambient relative humidity were maintained at 35 ± 1 °C and 65 ± 5%, respectively. The compressor speed was varied in the range between 1000 and 3000 rpm. The results showed that the coefficient of performance of an automobile air conditioner working with R430A was found to be 12–20% higher with 6–11% reduced compressor power consumption when compared to R134a. The R430A has 2–6 °C higher compressor discharge temperature when compared to R134a. The physical stability of the lubricant used in the compressor was retained while operating with R430A. The maximum exergy destruction occurs in the compressor (0.28 kW for R134a and 0.24 kW for R430A) followed by evaporator (0.16 kW for R134a and 0.14 kW for R430A), condenser (0.14 for R134a and 0.12 kW for R430A) and expansion valve (0.043 kW for R134a and 0.039 kW for R430A) at a compressor speed of 1000 ± 10 rpm. The exergy destruction of the system operating with R430A was found to be 12–28% lower when compared to R134a systems due to its favorable thermo-physical properties. The total equivalent warming impact of R430A was found to be lower when compared to R134a by about 47.3%, 35% and 32.4% for LPG, petrol and diesel vehicles, respectively. The results confirmed that R430A is a good drop-in substitute to replace R134a in existing automobile air conditioning systems.

A review on substitution strategy of non-ecological refrigerants from vapour compression-based refrigeration, air-conditioning and heat pump systems

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.

Although use of automobile air conditioning (AC) was shown to reduce in-vehicle particle levels, the characterization of its microbial aerosol exposure risks is lacking. Here, both AC and engine filter dust samples were collected from 30 automobiles in four different geographical locations in China. Biological contents (bacteria, fungi, and endotoxin) were studied using culturing, high-throughput gene sequence, and Limulus amebocyte lysate (LAL) methods. In-vehicle viable bioaerosol concentrations were directly monitored using an ultraviolet aerodynamic particle sizer (UVAPS) before and after use of AC for 5, 10, and 15 min. Regardless of locations, the vehicle AC filter dusts were found to be laden with high levels of bacteria (up to 26,150 CFU/mg), fungi (up to 1287 CFU/mg), and endotoxin (up to 5527 EU/mg). More than 400 unique bacterial species, including human opportunistic pathogens, were detected in the filter dusts. In addition, allergenic fungal species were also found abundant. Surprisingly, unexpected fluorescent peaks around 2.5 μm were observed during the first 5 min use of AC, which was attributed to the reaerosolization of those filter-borne microbial agents. The information obtained here can assist in minimizing or preventing the respiratory allergy or infection risk from the use of automobile AC system.

The environmental protocols lead to analysing various refrigerants minimum global warming potential (GWP) to substitute high GWP R134a in an automobile air conditioning (AAC) system. The present study deals with the thermodynamic analysis of the AAC unit using R1234yf/R134a refrigerant mixtures under three-vehicle speed conditions such as idling (L-900 rpm), city limit (M-1800 rpm), and high speed (H-2700 rpm). The mass fractions of R1234yf/R134a such as 0:1, 1:0, 0.9:0.1, 0.8:0.2, 0.7:0.3, 0.6:0.4 and 0.5:0.5 were considered in this analysis. The cooling capacity and coefficient of performance (COP) of R1234yf were observed to be poorer than that of the existing R134a by up to 10.4% and 8.3%. The addition of R134a in R1234yf reduced the performance gap between the existing R134a system under all the speed conditions. There was an increase cooling capacity and COP of the AAC by up to 6.4% and 4.9% was found with the addition of 0.5 mass fraction of R134a in R1234yf. However, the GWP of the refrigerant mixture was increased with rise in R134a mass fraction of which causes more direct CO2 emission from the AAC system. This study prevailed that the use of R1234yf/R134a mixture (0.5:0.5 by a mass fraction) performed very much similar to that of R134a in the AAC unit. Further, the R1234yf/R134a mixture (0.9:0.1 by a mass fraction) is suggested to use in the AAC system to satisfy the environmental protocols (GWP < 150).

Background/A car air conditioner AC filter is a suitable place for microbial growth. Fungal structures or/ andtheir by-products are pollutants of car air space. They are transmitted via air current forward passengers. Mostisolates were reported as allergens and mycotoxins producers. Chemical and less nonchemical treatmentswere followed to solve this problem. The current study aims to isolate and identify fungi associated withCAC filters and discuss the relationship between the fungal community with car age and the types of seatcoats. Also, we inspected the antifungal activity of the vapor and liquid phases of five essential oils invitro. Methods/ A cross-section study was followed, a swap samples were collected during one week. Theywere cultured on Sabouroad’s dextrose agar and Typha pollens agar. Plates were incubated at (25oC ±2).The highest occurrence% were Penicillium sp. &gt; Alternaria sp. &gt; Aspergillus (3sp.), while Acremoniumsp.,Rhizopus sp., Rodotorula sp. and Stachybotrys sp., showed low O% as well as yellow yeast and sterilemycelia. The crude oils of Hacinathus sp., Cymbopogon citratus, Myrtus communis, Eucalyptus sp.,and Cyperus rotundus were extracted and examined. ANOVA test showed that C.citratus oil vapor phasesignificantly affects the dominant isolate. Conclusion/ Car AC filter is a source of fungal structures withhealth impact. Liquid and vapor phases of EOs are probably practical alternatives to control fungal ACcontamination

&lt;div class="section abstract"&gt;&lt;div class="htmlview paragraph"&gt;Per - and polyfluoroalkyl substances – known as PFAS are man-made chemicals that do not occur naturally. PFAS are widely used, long lasting chemicals, components of which break down very slowly over time. Scientific studies have shown that exposure to some PFAS in the environment may be linked to harmful health effects in humans and animals. Because of their widespread use and their persistence in the environment, many PFAS are found in human and animals’ blood all over the world and are present at low levels in a variety of food products and in the environment. PFAS are found in water, air, fish, and soil at locations across the nation and the globe.&lt;/div&gt;&lt;div class="htmlview paragraph"&gt;Both refrigerants (HFC-134a &amp;amp; HFO-1234yf) that are currently used in mobile air conditioning systems (MACS) create PFAS. Hence, various countries are looking into banning chemicals that create PFAS. Natural refrigerants are being proposed as alternative refrigerants as they do not create PFAS. Hence, Propane (R290) and Carbon-Dioxide (R744) are being considered as alternate refrigerants for mobile HVAC systems for internal combustion engine (ICE) vehicles and for electric vehicles (EVs). However, propane is highly flammable, and carbon-dioxide operates at extremely high pressures that needs to be addressed.&lt;/div&gt;&lt;div class="htmlview paragraph"&gt;In this paper, the author has presented the following details: (i) Current situation of PFAS that the world is facing by providing details of actions by European countries, US and Japan. (ii) Details of the alternate refrigerants including thermodynamic and thermophysical properties comparison that affects heat transfer coefficients and pressure gradients during single and two-phase fluid flow. (iii) Safety Considerations. (iv) Details of the test that the author has conducted with hydrocarbon refrigerants and with carbon-dioxide. (v) Finally, the details with heat pump system architectures are presented using natural refrigerants as direct expansion and indirect systems from a safety and performance perspective for ICE and EVs. It should be noted that currently many OEMs and suppliers have heat pumps systems with high degree of complexity and there is no common standard architecture for the ICE/EV heat pumps system.&lt;/div&gt;&lt;/div&gt;

The widespread use of automobiles and the increased duration spent within automobiles equipped with air conditioning systems have prompted various countries to enforce regulations that advocate for eco-friendly cooling substances (refrigerants) characterized by a slight global warming potential (GWP) and the absence of an ozone depletion potential (ODP). The imperative for automobiles to possess air conditioning systems that are both high-performing and eco-conscious has emerged as a means to mitigate their ecological impact, reduce fuel usage, and minimize carbon emissions. Zeotropic refrigerants, with a lower GWP than traditional alternatives, contribute to sustainability in car air conditioning by reducing the environmental impact and enhancing the energy efficiency, aligning with global regulations and fostering innovation in the automotive industry. This shift signifies a commitment to mitigating climate change and adopting environmentally conscious practices. The objective of the present study is to introduce blends of zeotropic refrigerants based on CO2 (R-744), namely R455A (a blend of R-744, R-32, and R-1234yf), R469A (a blend of R-744, R-32, and R-125), and R472A (a blend of R-744, R-32, and R-134a), to enhance the thermodynamic performance of pure CO2 refrigerant. Through the utilization of the Aspen HYSYS V11 software, an investigation is carried out involving thermodynamic energy and exergy analyses, as well as system optimization for an automotive air conditioning (AAC) system utilizing these novel zeotropic refrigerant blends, in comparison with the use of R-744 as the refrigerant. The study delves into the impact of parameters such as average evaporator temperature, condenser/cooler pressure, refrigerant flow rate, and condenser/cooler outlet temperature on AACs’ output parameters and subsequently presents the findings. The outcomes reveal that, under equivalent operational circumstances, the adoption of R455A, R469A, and R472A offers improvements in coefficient of performance (COP) by 35.4%, 18.75%, and 2%, respectively, when compared to R744. This shift is advantageous as it mitigates leakage-related issues stemming from the elevated operational pressure of R744 and eliminates the need for cumbersome equipment. R455A and R469A obtain the greatest COP and exergy efficiency (ηex) values, measuring 4.44 and 4.55, respectively, at the identical operating conditions with optimal condenser/cooler pressures of the examined blends. Furthermore, eco-friendly refrigerants R455A and R472A are recommended for integration into AAC systems in vehicles, as they help combat global warming and protect natural surroundings and leakage issues.

Review of hydrocarbon refrigerants as drop-in alternatives to high-GWP refrigerants in VCR systems: The case of R290

In the present paper, an attempt has been made to review the performance of new refrigerant mixtures employed in vapour compression-based refrigeration, air-conditioning and heat pump units. The studies reported with refrigerant mixtures are categorized into six groups as follows: (i) hydrocarbon (HC), (ii) hydroflurocarbons (HFC), (iii) HFC/HC, (iv) hydrochloroflurocarbons (HCFC), (v) carbon dioxide (R744) and (vi) ammonia (R717). This paper explores the studies reported with new refrigerant mixtures in domestic refrigerators, commercial refrigeration systems, air conditioners, heat pumps, chillers and in automobile air conditioners. In addition, the technical difficulties faced with new refrigerant mixtures, further research needs in this field and future refrigerant options for new upcoming systems have been discussed in detail. This paper concludes that HC based refrigerant mixtures are identified as a long-term alternative to phase out the existing halogenated refrigerants in the vapour compression-based systems. Copyright © 2010 John Wiley & Sons, Ltd.

The Environmental Protection Agency is clearing the way for additional chemicals to replace hydrofluorocarbons (HFCs), potent greenhouse gases that are used as refrigerants. An EPA proposal released in late March “would reduce the use and emissions of some of the most harmful HFCs, which are thousands of times more potent than carbon dioxide,” in terms of their global warming potential, says agency Administrator Gina McCarthy. As part of its effort to combat human-caused climate change, the Obama Administration is promoting a global phaseout of HFCs. EPA’s proposal would also allow use of safer, more climate-friendly alternatives to HFCs. For instance, it would clear the way for more uses of hydrofluoroolefin-1234yf, a substance gaining popularity in automobile air conditioners as an alternative for HFC-134a. HFO-1234yf has less than one thousandth of the global warming potential of HFC-134a. The proposal would allow use of the HFO-1234yf in heavy-duty pickup trucks and vans

Anaesthetic in the garb of a propellant.

: According to Montreal Protocol, HCFC22 (hydro chlorofluorocarbon), a commonly used refrigerant in domestic refrigeration and air-conditioner, must be phased out owing to its environmental problem. Several natural substances including ammonia, carbon dioxide, water and hydrocarbon (HC) such as propane (HC290) and butane (HC600) and their mixtures have immerged as close substitute. Literature showed that pure HC refrigerant may not be suitable enough because of the difference in operating pressure and volumetric cooling capacity when compared with HCFC22. The main objective of this study is to theoretically investigate different ratios of HC refrigerants HC290/HC600 mixtures flowing through adiabatic capillary tube using homogenous model. In this study, the percentage by volume of HC290 was varied from 30 to 40 % in a step of 5%. The pressure at the two extreme ends and temperature along the capillary tube, using HCFC22 refrigerant, which was used as benchmark, was experimentally determined in the air-conditioning (AC) system. Comparing the model results with the experimental data showed that HC refrigerants HC290/HC600 in ratio 35%/65% gave 2.95% minimum error and thus it can be used as a substitute to HCFC22 in the split-type AC system.

Cars with air conditioning systems have become the norm, but these systems can be dangerous for human health as a result of the accumulation of different microorganisms, including pathogenic ones, causing severe allergy or inflammation problems. The novel purpose of this study is 2-fold: on the one hand, to test different disinfection agents on a new area, that is, automobile cabins, and on the other, to compare activity in the gas phase of these agents for disinfection of car air conditioning and cabin surfaces. This study shown that tested disinfectant agents dedicated for decontamination medical areas (agent based on peracetic acid and an agent containing didecyldimethylammonium chloride, 2-phenoxyethanol with cinnamaldehyde) can be successfully used for disinfection car air conditioning and cabin surfaces. Both disinfectants were examined in comparison to a commercial “ready-to-use” spray from a local supermarket dedicated to car air conditioning disinfection. Our research found that very effective agents in this regard were acid stabilized by hydrogen peroxide applied by fumigator, and a combination of didecyldimethylammonium chloride, 2-phenoxyethanol, and cinnamaldehyde applied by atomizer. Tested disinfection procedures of car air conditioning significantly influence the quality of cabin air and surfaces by reducing the amount of microorganisms. The comparison of disinfection properties studied agents in the gas phase reveal statistically significant differences between it effect for disinfection car air conditioning and cabin surfaces. Our research found that very effective agents in this regard were acid stabilized by hydrogen peroxide applied by fumigator, and a combination of didecyldimethylammonium chloride, 2-phenoxyethanol, and cinnamaldehyde applied by atomizer. Tested disinfection procedures of car air conditioning significantly influence the quality of cabin air and surfaces by reducing the amount of microorganisms.