Air Conditioning Systems in Vehicles: Approaches and Challenges
Abstract
1. Introduction
2. History of Automotive Air Conditioning Systems
2.1. Technological Evolution of Air Conditioning Systems
2.2. Early Systems vs. Modern Technologies
2.3. Impact of Regulations and Market Demands on Development
3. The Operating Principle of Air Conditioning Systems
3.1. Description of Main Components: Compressor, Condenser, Evaporator, Fan
3.2. Refrigeration Cycle
4. Modern Types of Air Conditioning Systems
4.1. Traditional Air Conditioning
4.2. Adsorption-Based Systems
4.3. Adding Functionalities of Intelligent Air Conditioning Systems
5. Environmental Impact
Analysis of Refrigerants: HFC-134a vs. HFO-1234yf
6. Current Challenges
7. Future Directions
Comparative Outlook of Emerging Cooling Technologies
8. Conclusions
Author Contributions
Funding
Institutional Review Board Statement
Informed Consent Statement
Data Availability Statement
Conflicts of Interest
Abbreviations
A/C | air conditioning |
AI | artificial intelligence |
ASHRAE | American Society of Heating, Refrigerating and Air-Conditioning Engineers |
BMS | Battery Management System |
CO2 | carbon dioxide |
EV | electric vehicle |
GWP | global warming potential |
HFC | hydrofluorocarbon |
HFO | Hydrofluoroolefin |
HVAC | Heating, Ventilation and Air Conditioning |
IoT | Internet of Things |
OEM | original equipment manufacturer |
PFAS | per- and polyfluoroalkyl substances |
R&D | Research and Development |
TFA | trifluoroacetic acid |
VCR | Vapor Compression Refrigeration |
Wp | Watt-peak (maximum power output of a solar panel) |
References
- Vashisht, S.; Rakshit, D. Recent Advances and Sustainable Solutions in Automobile Air Conditioning Systems. J. Clean. Prod. 2021, 329, 129754. [Google Scholar] [CrossRef]
- Shah, R.K. Automotive Air Conditioning Systems—Historical Developments, the State of Technology, and Future Trends. Heat Transf. Eng. 2009, 30, 720–735. [Google Scholar] [CrossRef]
- Jiangzhou, S.; Wang, R.Z.; Lu, Y.Z.; Xu, Y.X.; Wu, J.Y. Experimental study on locomotive driver cabin adsorption air conditioning prototype machine. Energy Convers. Manag. 2005, 46, 1655–1665. [Google Scholar] [CrossRef]
- Alahmer, A.; Ghoniem, R.M. Improving Automotive Air Conditioning System Performance Using Composite Nano-Lubricants and Fuzzy Modeling Optimization. Sustainability 2023, 15, 9481. [Google Scholar] [CrossRef]
- Diga, D.; Severin, I.; Ignat, N.D. Quality Study on Vehicle Heat Ventilation and Air Conditioning Failure. Sustainability 2021, 13, 13441. [Google Scholar] [CrossRef]
- Khan, A.; Bradshaw, C.R. Quantitative comparison of the performance of vapor compression cycles with compressor vapor or liquid injection. Int. J. Refrig. 2023, 154, 386–394. [Google Scholar] [CrossRef]
- Lou, H.H.; Huang, Y.L. Fuzzy-Logic-Based Process Modeling Using Limited Experimental Data. Eng. Appl. Artif. Intell. 2000, 13, 121–135. [Google Scholar] [CrossRef]
- Wang, H.; Amini, M.R.; Song, Z.; Sun, J.; Kolmanovsky, I. Combined Energy and Comfort Optimization of Air Conditioning System in Connected and Automated Vehicles. In Proceedings of the Dynamic Systems and Control Conference, Park City, Utah, 8–11 October 2019; American Society of Mechanical Engineers: New York, NY, USA, 2019; Volume 59148, p. V001T08A001. [Google Scholar]
- Alahmer, H.; Alahmer, A.; Alkhazaleh, R.; Alrbai, M.; Alamayreh, M.I. Applied Intelligent Grey Wolf Optimizer (IGWO) to Improve the Performance of CI Engine Running on Emulsion Diesel Fuel Blends. Fuels 2023, 4, 4. [Google Scholar] [CrossRef]
- Zun, M.T.; Ahmad, M.S.; Fayaz, H.; Selvaraj, J.; Ahmed, W.; Wang, Y.; Khedher, N.; Silitonga, A.S.; Elfasakhany, A.; Kalam, M.A. Towards Techno-Economics of Green Hydrogen as a Primary Combustion Fuel for Recreational Vehicle Vapor Absorption Refrigeration System. Sustain. Energy Technol. Assess. 2023, 56, 103007. [Google Scholar] [CrossRef]
- Aly, W.I.A.; Abdo, M.; Bedair, G.; Hassaneen, A.E. Thermal Performance of a Diffusion Absorption Refrigeration System Driven by Waste Heat from Diesel Engine Exhaust Gases. Appl. Therm. Eng. 2017, 114, 621–630. [Google Scholar] [CrossRef]
- MAHLE. Compact Knowledge: Vehicle Air Conditioning. Available online: https://www.mahle-aftermarket.com/media/homepage/facelift/media-center/klima/kompaktwissen-ac-fahrzeugklimatisierung-en-screen.pdf (accessed on 10 May 2025).
- Vranău, A.M.; Bujoreanu, C.; Sachelarie, A.; Caunii, V. Some Considerations on Vibrations and Noise of Automotive HVAC System. IOP Conf. Ser. Mater. Sci. Eng. 2021, 997, 012023. [Google Scholar] [CrossRef]
- Vasta, S. Adsorption Air-Conditioning for Automotive Applications: A Critical Review. Energies 2023, 16, 5382. [Google Scholar] [CrossRef]
- IEA Technology Roadmap. Energy-Efficient Buildings: Heating and Cooling Equipment. 2013. Available online: https://www.iea.org/reports/technology-roadmap-energy-efficient-buildings-heating-and-cooling-equipment (accessed on 12 February 2020).
- Chen, X.; Liang, K.; Li, Z.; Zhao, Y.; Xu, J.; Jiang, H. Experimental assessment of alternative low global warming potential refrigerants for automotive air conditioners application. Case Stud. Therm. Eng. 2020, 22, 100800. [Google Scholar] [CrossRef]
- Flannery, B.; Lattin, R.; Finckh, O.; Berresheim, H.; Monaghan, R.F.D. Development and experimental testing of a hybrid Stirling engine-adsorption chiller auxiliary power unit for heavy trucks. Appl. Therm. Eng. 2017, 112, 464–471. [Google Scholar] [CrossRef]
- Chan, C.; Chau, K. Modern Electric Vehicle Technology; Oxford University Press on Demand: New York, NY, USA, 2001. [Google Scholar]
- Flannery, B.; Finckh, O.; Berresheim, H.; Monaghan, R.F.D. Refroidisseur à adsorption àmoteur Stirling hybride pour des applications d’unités de puissance auxiliaire pour des camions. Int. J. Refrig. 2017, 76, 356–366. [Google Scholar] [CrossRef]
- Jiangzhou, S.; Wang, R.Z.; Lu, Y.Z.; Xu, Y.X.; Wu, J.Y. Experimental Investigations on Adsorption Air-Conditioner Used in Internal-Combustion Locomotive Driver-Cabin. Available online: www.elsevier.com/locate/apthermeng (accessed on 1 June 2023).
- Environmental Protection Agency. Acceptable Refrigerants and Their Impacts. Available online: https://www.epa.gov/mvac/acceptable-refrigerants-and-their-impacts (accessed on 12 January 2025).
- Roy, D.; el Khoury, K.; Clodic, D.; Petitjean, C. Modeling of in-Vehicle Heat Transfers Using Zonal Approach; SAE Technical Paper, No. 2001-01-1333; SAE: Warrendale, PA, USA, 2001. [Google Scholar]
- Kaushik, S.; Chen, K.; Han, T.; Khalighi, B. Micro-Cooling/Heating Strategy for Energy Efficient HVAC System. SAE Int. J. Mater. Manuf. 2011, 4, 853–863. Available online: http://www.jstor.org/stable/26273823 (accessed on 24 September 2022). [CrossRef]
- Smierciew, K.; Gagan, J.; Butrymowicz, D.; Karwacki, J. Experimental investigations of solar driven ejector air conditioning system. Energy Build. 2014, 80, 260–267. [Google Scholar] [CrossRef]
- Trust, C. Heating, Ventilation and Air Conditioning Overview Guide. 2017. Available online: https://www.carbontrust.com/resources/guides/energy-efficiency/heating-ventilation-and-airconditioning-hvac/ (accessed on 12 February 2020).
- Lee, J.T.; Kwon, S.K.; Lim, Y.S.; Chon, M.S.; Kim, D.S. Effect of Air Conditioning on Driving Range of Electric Vehicle for Various Driving Modes; SAE Technical Paper, No. 2013-01-0040; SAE: Warrendale, PA, USA, 2013. [Google Scholar]
- Da Silva, D.L.; De Oliveira, I.S.; Juliani, A.D.P.; de Cordova, G.M. Automotive Air-Conditioning System Thermal Performance Assessment: An Experimental Approach Combining First and Second Laws of Thermodynamics. J. Braz. Soc. Mech. Sci. Eng. 2024, 46, 703. [Google Scholar] [CrossRef]
- Kambly, K.R.; Bradley, T.H. Estimating the HVAC energy consumption of plug-in electric vehicles. J. Power Sources 2014, 259, 117–124. [Google Scholar] [CrossRef]
- Kiss, T.; Lustbader, J.; Leighton, D. Modeling of an Electric Vehicle Thermal Management System in MATLAB/Simulink; No. NREL/CP-5400-63419; National Renewable Energy Lab.: Golden, CO, USA, 2015. [Google Scholar]
- Farrington, R.; Rugh, J. Impact of Vehicle Air Conditioning on Fuel Economy, Tailpipe Emissions, and Electric Vehicle Range; NREL/CP-540-28960; Earth Technologies Forum: Washington, DC, USA, 2000. Available online: https://www.nrel.gov/docs/fy00osti/28960.pdf (accessed on 24 September 2022).
- Shi, X.; Pan, J.; Wang, H.; Cai, H. Battery electric vehicles: What is the minimum range required? Energy 2019, 166, 352–358. [Google Scholar] [CrossRef]
- Samadani, E.; Fraser, R.; Fowler, M. Evaluation of Air Conditioning Impact on the Electric Vehicle Range and Li-Ion Battery Life; SAE Technical Paper, No. 2014-01-1853; SAE: Warrendale, PA, USA, 2014. [Google Scholar]
- Sukri, M.F.; Musa, M.N.; Senawi, M.Y.; Nasution, H. Achieving a better energy-efficient automotive air conditioning system: A review of potential technologies and strategies for vapor compression refrigeration cycle. Energy Effic. 2015, 8, 1201–1229. [Google Scholar] [CrossRef]
- Soica, A.; Țărulescu, S.; Elie, R.; Vonimanitra Juliana, R.R.; Herizo, R.; Popa, M. The Impact of Road Transport on the Level of CO2 in Urban Areas. In Proceedings of the CONAT 2024 International Congress of Automotive and Transport Engineering, Brasov, Romania , 6–8 November 2024; Springer: Cham, Switzerland, 2024. [Google Scholar]
- Chaney, L.; Thundiyil, K.; Chidambaram, S.; Abbi, Y.P.; Andersen, S. Fuel Savings and Emission Reductions from Next-Generation Mobile Air Conditioning Technology in India. In Proceedings of the Vehicle Thermal Management Systems Conference & Exhibition (VTMS-8), Nottingham, UK, 20–24 May 2007. [Google Scholar]
- Kang, B.H.; Lee, H.J. A Review of Recent Research on Automotive HVAC Systems for EVs. Int. J. Air Cond. Refrig. 2017, 25, 1730003. [Google Scholar] [CrossRef]
- Wang, R.Z.; Oliveira, R.G. Adsorption refrigeration—An efficient way to make good use of waste heat and solar energy. Prog. Energy Combust. Sci. 2006, 32, 424–458. [Google Scholar] [CrossRef]
- Liu, Y.; Zhang, X. Adsorption cooling systems in vehicles: Recent advancements and challenges. Appl. Therm. Eng. 2017, 124, 10–25. [Google Scholar] [CrossRef]
- Volkswagen AG. Self-Study Programme 135: Climatronic–Construction and Function; Volkswagen AG: Wolfsburg, Germany, 1998. [Google Scholar]
- Yokoyama, A.; Osaka, T.; Imanishi, Y. Thermal management system for electric vehicles. SAE Int. J. Mater. Manuf. 2011, 4, 1277–1285. Available online: https://www.jstor.org/stable/26273859 (accessed on 23 September 2022). [CrossRef]
- ProMotor. Available online: https://www.promotor.ro (accessed on 5 March 2025).
- Kowsky, C.; Wolfe, E.; Leitzel, L.; Oddi, F. Unitary HPAC system. SAE Int. J. Passeng. Cars Mech. Syst. 2012, 5, 1016–1025. [Google Scholar] [CrossRef]
- Torregrosa-Jaime, B.; Vasile, C.; Risser, M.; Muller, C.; Corberan, J.; Paya, J. Application of magnetocaloric heat pumps in mobile air conditioning. SAE Int. J. Passeng. Cars Mech. Syst. 2013, 6, 520–528. [Google Scholar] [CrossRef]
- Wang, M.; Craig, T.; Wolfe, E.; Laclair, T.J.; Gao, Z.; Levin, M.; Danrich, D.; Furqan, S. Integration and Validation of a Thermal Energy Storage System for Electric Vehicle Cabin Heating; Oak Ridge National Lab.: Oak Ridge, TN, USA, 2017. [Google Scholar]
- Wang, M.; WolfelV, E.; Craig, T.; Laclair, T.J.; Gao, Z.; Abdelaziz, O. Design and Testing of a Thermal Storage System for Electric Vehicle Cabin Heating; Oak Ridge National Lab.: Oak Ridge, TN, USA, 2016. [Google Scholar]
- Wang, L.W.; Jiang, L.; Gao, J.; Gao, P.; Wang, R.Z. Analysis of resorption working pairs for air conditioners of electric vehicles. Appl. Energy 2017, 207, 594–603. [Google Scholar] [CrossRef]
- Qi, Z. Advances on air conditioning and heat pump system in electric vehicles—A review. Renew. Sustain. Energy Rev. 2014, 38, 754–764. [Google Scholar] [CrossRef]
- Bentrcia, M.; Alshitawi, M.; Omar, H. Developments of alternative systems for automotive air conditioning—A review. J. Mech. Sci. Technol. 2018, 32, 1857–1867. [Google Scholar] [CrossRef]
- Quick, D. Solar-Powered Air Conditioning for Vehicles. 17 November 2010. Available online: https://phys.org/news/2011-10-solar-powered-air-conditioning-vehicles.html (accessed on 23 September 2022).
- Lethwala, Y.; Garg, P. Development of auxiliary automobile air conditioning system by solar energy. Int. Res. J. Eng. Technol. 2017, 4, 737–742. Available online: www.irjet.net (accessed on 23 September 2022).
- Ingersoll, J. Integration of Solar Cells in Automobiles as a Means to Reduce the Air Conditioner Capacity and Improve Comfort; Kluwer Academic Publishers: Norwell, MA, USA, 1989. [Google Scholar]
- Pang, W.; Yu, H.; Zhang, Y.; Yan, H. Solar photovoltaic based air cooling system for vehicles. Renew. Energy 2019, 130, 25–31. [Google Scholar] [CrossRef]
- Alani, W.K.; Zheng, J.; Fayad, M.A.; Lei, L. Enhancing the fuel saving and emissions reduction of light-duty vehicle by a new design. Case Stud. Therm. Eng. 2022, 30, 101798. [Google Scholar] [CrossRef]
- Al-Ghasem, A.; Ussaleh, N. Air Conditioner Control Using Neural Network and PID Controller. In Proceedings of the 2012 8th International Symposium on Mechatronics and Its Applications, Sharjah, United Arab Emirates, 10–12 April 2012. [Google Scholar]
- Natural Refrigerants. Certain HFCs and HFOs Are in PFAS Group That Five EU Countries Intend to Restrict. Available online: https://naturalrefrigerants.com/certain-hfcs-and-hfos-are-in-pfas-group-that-five-eu-countries-intend-to-restrict/ (accessed on 12 January 2025).
- Attia, A.; Rezeka, S.F.; Saleh, A.M. Fuzzy logic control of air conditioning system in residential buildings. Alex. Eng. J. 2015, 54, 395–403. [Google Scholar] [CrossRef]
- Komatsu, Y.; Hamada, K.; Nukaga, N.; Ueda, T.K.Y.; Matsubara, E.; Jinno, N. Area detection technology for Air Conditioner. In Proceedings of the 2015 54th Annual Conference of the Society of Instrument and Control Engineers of Japan (SICE), Hangzhou, China, 28–30 July 2015. [Google Scholar]
- IGSD. Status of Patents and Legal Challenges: HFO-1234yf. Available online: https://www.igsd.org/wp-content/uploads/2021/12/Status-of-Patens-and-Legal-Challenges-HFO-1234yf-3Dec21.pdf (accessed on 12 January 2025).
- Gheorghe, C.; Soica, A. Revolutionizing Urban Mobility: A Systematic Review of AI, IoT, and Predictive Analytics in Adaptive Traffic Control Systems for Road Networks. Electronics 2025, 14, 719. [Google Scholar] [CrossRef]
- Torregrosa-Jaime, B.; Paya, J.; Corberan, J. Design of Efficient Air Conditioning Systems for Electric Vehicles. SAE Int. J. Altern. Power. 2013, 2, 291–303. [Google Scholar] [CrossRef]
- Lee, J.; Kim, J.; Park, J.; Bae, C. Effect of the air conditioning system on the fuel economy in a gasoline engine vehicle. Proc. Inst. Mech. Eng. Part D J. Automob. Eng. 2013, 227, 66–77. [Google Scholar] [CrossRef]
- Huff, S.; West, B.; Thomas, J. Effects of Air Conditioner Use on Real-World Fuel Economy; SAE Technical Paper, No. 2013-01-0551; SAE: Warrendale, PA, USA, 1992. [Google Scholar]
- Dieckmann, J.; Mallory, D. Variable Speed Compressor, HFC-134a Based Air Conditioning System for Electric Vehicles; SAE Technical Paper No. 920444; SAE: Warrendale, PA, USA, 1992. [Google Scholar]
- Zhang, Q.; Meng, Y.; Greiner, C.; Soto, C.; Schwartz, W.; Jennings, M. Air Conditioning System Performance and Vehicle Fuel Economy Trade-Offs for A Hybrid Electric Vehicle; SAE Technical Paper, No. 2017-01-0171; SAE: Warrendale, PA, USA, 2017. [Google Scholar]
- Warule, P.B.; Jadhav, V.V. Optimization of AC Control in Hybrid Electric Vehicles During Urban Drive Conditions; SAE Technical Paper, No. 2017-26-0087; SAE: Warrendale, PA, USA, 2017. [Google Scholar]
- Adhikari, V.P.; Nasser, A.; Nagpurwala, Q.H. Numerical Studies on the Effect of Cooling Vent Setting and Solar Radiation on Air Flow and Temperature Distribution in a Passenger Car; SAE Technical Paper, No. 2009-28-0048; SAE: Warrendale, PA, USA, 2009. [Google Scholar]
- Lin, P. Performance evaluation and analysis of EV air conditioning system. World Electr. Veh. J. 2010, 4, 197–201. [Google Scholar] [CrossRef]
- Rugh, J.P.; Hendricks, T.J.; Koram, K. Effect of Solar Reflective Glazing on Ford Explorer Climate Control, Fuel Economy, and Emissions; SAE Technical Paper, No. 2001-01-3077; SAE: Warrendale, PA, USA, 2001; Available online: https://www.sae.org/publications/technical-papers/content/2001-01-3077/ (accessed on 23 August 2019).
- Farrington, R.B.; Rugh, J.P.; Barber, G.D. Effect of Solar-Reflective Glazing on Fuel Economy, Tailpipe Emissions, and Thermal Comfort. SAE Trans. 2000, 109, 2329–2336. [Google Scholar]
- Türler, D.; Hopkins, D.; Goudey, H. Reducing Vehicle Auxiliary Loads Using Advanced Thermal Insulation and Window Technologies; SAE Technical Paper, No. 2003-01-1076; SAE: Warrendale, PA, USA, 2003. [Google Scholar]
- Han, T.; Chen, K. Assessment of Various Environmental Thermal Loads on Passenger Compartment Soak and Cool-Down Analyses; SAE Technical Paper, No. 2009-01-1148; SAE: Warrendale, PA, USA, 2009; Available online: https://www.sae.org/publications/technical-papers/content/2009-01-1148/ (accessed on 23 September 2022).
- Han, T.; Chen, K.; Khalighi, B.; Curran, A.; Pryor, J.; Hepokoski, M. Assessment of Various Environmental Thermal Loads on Passenger Thermal Comfort. SAE Int. J. Passeng. Cars 2010, 3, 830–841. [Google Scholar] [CrossRef]
- Gasworth, S.; Tankala, T.; Kancharla, A.; Shuler, S. Improved Battery Performance in Electric Vehicles via Reduced Glazing Thermal Conductivity; SAE Technical Paper, No. 2011-01-1341; SAE: Warrendale, PA, USA, 2011. [Google Scholar]
- Subiantoro, A.; Ooi, K.T.; Stimming, U. Energy saving measures for automotive air conditioning (AC) system in the tropics. In Proceedings of the International Refrigeration and Air Conditioning Conference, West Lafayette, IN, USA, 14–17 July 2014; p. 1361. Available online: http://docs.lib.purdue.edu/iracc/1361 (accessed on 23 September 2022).
- Next-Generation Refrigerants: Ultra-Low Global Warming Potential Solutions. U.S. Environmental Protection Agency. Available online: https://www.epa.gov (accessed on 12 January 2025).
- Fujita, A.; Nakamura, Y.; Tokura, Y. Magnetic Refrigeration Material Operating at a Full Temperature Range Required for Hydrogen Liquefaction. Nat. Commun. 2022, 13, 1501. [Google Scholar]
- Vishnu, G.; Kaliyaperumal, D.; Jayaprakash, R.; Karthick, A.; Chinnaiyan, V.K.; Ghosh, A. Review of Challenges and Opportunities in the Integration of Electric Vehicles to the Grid. World Electr. Veh. J. 2023, 14, 259. [Google Scholar] [CrossRef]
- Heat Pumps for Energy-Efficient Automotive Climate Control. Applied Thermal Engineering. Available online: https://www.sciencedirect.com (accessed on 12 January 2025).
- Climate Control Innovations for Autonomous Vehicles. SAE International Technical Papers. Available online: https://www.sae.org (accessed on 12 January 2025).
- Mehmood, A.; Al-Azzani, M.A.K.A.; A-Dhahri, I.Q.M.; Al-Omairi, S.R.S.J.; Al-Mamari, A.A.A.; Al-Dhahli, M.R.S. Case Study of Solar Integration in HVAC Systems: Efficiency and Sustainability Outcomes. Indian J. Energy Energy Resour. 2024, 3, 1–9. [Google Scholar] [CrossRef]
- Fountain, M.; Arens, E.; de Dear, R.; Bauman, F.; Miura, K. Locally Controlled Air Movement Preferred in Warm Isothermal Environments. Available online: https://escholarship.org/uc/item/0f2524sk (accessed on 23 September 2022).
- Melikov, A.K.; Zhou, G. Air movement at the neck of the human body. In Proceedings of the Indoor Air ‘96, Nagoya, Japan, 21–26 July 1996; pp. 209–214. [Google Scholar]
- Niu, J.; Gao, N.; Phoebe, M.; Huigang, Z. Experimental study on a chair-based personalized ventilation system. Build. Environ. 2007, 42, 913–925. [Google Scholar] [CrossRef]
- Oh, M.S.; Ahn, J.H.; Kim, D.W.; Jang, D.S.; Kim, Y. Thermal comfort and energy saving in a vehicle compartment using a localized air conditioning system. Appl. Energy 2014, 133, 14–21. [Google Scholar] [CrossRef]
- ASHRAE A2L Standards. Available online: https://advancedmaterials.honeywell.com/content/dam/advancedmaterials/en/documents/document-lists/refrigerants/technical/A2L-Refrigerants-White-Paper.pdf (accessed on 4 June 2025).
Advantages/Disadvantages | Details | References |
---|---|---|
Advantages |
| [1,10] |
Disadvantages |
| [6,11] |
Advantages/Disadvantages | Details | References |
---|---|---|
Advantages | - Efficient operation under most conditions. - Easy integration into various vehicle types. | [1,19,20,21] |
Disadvantages | - Environmental concerns related to refrigerants. Requires regular maintenance. | [6,18,22,23] |
Technology Type | Key Advantages | Major Disadvantages | Quantitative Indicators | Application Area |
---|---|---|---|---|
Traditional (Compression-based) Air Conditioning | High efficiency for various types of spaces. Installation flexibility (central or individual systems). Long-term reliability and easy maintenance. Precise temperature control tailored to user needs. | High initial installation costs. Environmental impact due to refrigerants with high global warming potential. Regular maintenance required. High energy consumption, especially in extreme climates. | Cooling Capacity: Typically 3–7 kW GWP (HFC-134a): ~1300 CO2-equivalent | Passenger cars, commercial vehicles, residential, and commercial spaces |
Advantages | Disadvantages |
---|---|
Uses waste heat, reducing overall energy consumption. | Lower cooling capacity (approximately 1–3 kW) than compression-based systems (approximately 3–7 kW) [12]. |
Environmentally friendly, as it utilizes natural refrigerants, such as water. | Bulkier design, making it harder to integrate into compact vehicles. |
Silent operation due to the lack of moving parts. | Slower cooling process, which may not meet high-demand requirements. |
Well-suited for hybrid and electric vehicles, reducing battery load. | Higher initial investment and increased system complexity. |
Characteristic | Advantages | Disadvantages | Application Area | References |
---|---|---|---|---|
Energy Efficiency | Optimizes energy consumption, reducing fuel usage and emissions. | Initial setup and system calibration may require extensive development costs. | Electric and hybrid vehicles | [40,52] |
Personalized Comfort | Learns user preferences for temperature and airflow, improving the passenger experience. | Privacy concerns due to data collection on user behavior and preferences. | Passenger cars with adaptive climate systems | [53] |
Predictive Maintenance | Identifies potential system failures before they occur, reducing long-term maintenance costs. | May lead to over-dependence on AI, making manual troubleshooting more difficult. | All modern vehicles with connected services | [54] |
External Adaptation | Adjusts based on external conditions (e.g., sunlight direction, outside temperature). | Advanced sensors and software might increase manufacturing complexity and costs. | High-end or premium vehicles | [30,45] |
Intuitive Interfaces | Voice and touch controls make climate control more accessible and user-friendly. | System glitches in recognition (e.g., misinterpreted voice commands) can reduce usability. | Vehicles with human–machine interface (HMI) integration | [51] |
Sustainability | Reduces environmental impact through energy-efficient operation. | Recycling and disposal of advanced AI hardware may pose ecological challenges. | Future-focused electric vehicle platforms | [52] |
Characteristic | Adv./Disadv. | Details | Application Area | References |
---|---|---|---|---|
Global Warming Potential (GWP) | Advantage | HFO-1234yf has a GWP of less than 1, significantly reducing climate impact. | All modern vehicles comply with low-GWP regulations | [61,62] |
Global Warming Potential (GWP) | Disadvantage | HFC-134a has a GWP of approximately 1300, contributing significantly to global warming. | Legacy and older vehicle platforms | [61,62] |
Atmospheric Lifetime | Advantage | HFO-1234yf has a short atmospheric lifetime (~11 days), reducing its long-term environmental effects. | Eco-certified vehicle systems | [63] |
Atmospheric Lifetime | Disadvantage | HFC-134a persists in the atmosphere for ~14 years, prolonging its impact. | High-emission conventional systems | |
Environmental Degradation | Advantage | HFO-1234yf degrades faster, resulting in less accumulation in the atmosphere. | Modern climate-friendly systems | |
Environmental Degradation | Disadvantage | HFO-1234yf degrades entirely into trifluoroacetic acid (TFA), raising concerns about water pollution. | Environmental monitoring systems | [60] |
Regulatory Compliance | Advantage | HFO-1234yf complies with EU and Kigali Amendment GWP regulations. | Vehicles sold in the EU and under the Kigali targets | [62,64] |
Regulatory Compliance | Disadvantage | HFC-134a faces phase-out mandates under the Kigali Amendment and EU regulations. | Pre-2017 vehicle fleets | |
Energy Efficiency | Advantage | Both refrigerants exhibit similar energy efficiency in most systems. | General automotive A/C platforms | [65] |
Energy Efficiency | Disadvantage | Transitioning to HFO-1234yf may require new infrastructure and higher upfront costs. | OEMs and aftermarket services | |
Safety | Advantage | HFO-1234yf is less flammable than hydrocarbons. | Vehicles designed with enhanced safety features | [62,63] |
Safety | Disadvantage | HFO-1234yf is mildly flammable and requires additional safety measures. | All vehicles using HFO-1234yf | |
Economic Impact | Advantage | HFO-1234yf offers long-term compliance benefits, thereby avoiding penalties associated with high-GWP refrigerants. | Regulated automotive markets | [61,62] |
Economic Impact | Disadvantage | HFO-1234yf is more expensive than HFC-134a, raising initial costs for manufacturers and users. | Cost-sensitive manufacturers and markets |
Characteristic | HFC-134a | HFO-1234yf |
---|---|---|
Global Warming Potential (GWP) | ≈1300 | <1 |
Atmospheric Lifetime | ~14 years | ~11 days |
Safety Classification | Non-flammable (ASHRAE A1) | Mildly flammable (ASHRAE A2L) |
Environmental Impact | Long persistence; contributes to global warming | Degrades to TFA; environmental concerns remain |
Cost | Low (~ EUR 5–10/kg) | High (~ EUR 40–70/kg) |
Regulatory Status | Subject to phase-out (EU, Kigali) | Compliant with EU and Kigali Amendment |
Energy Efficiency | Comparable | Comparable, but requires system adaptation |
Infrastructure Compatibility | Widely compatible | Requires retrofit or redesign |
Challenge | Description | Application Area | References |
---|---|---|---|
Refrigerant Impact | Despite the shift to low-GWP refrigerants like HFO-1234yf, concerns persist about degradation into trifluoroacetic acid (TFA), accumulating in water sources. | All vehicle types using low-GWP refrigerants | [55,62] |
Compliance with Regulations | Manufacturers must adapt to international standards like the Kigali Amendment and EU directives to phase out high-GWP refrigerants. | OEMs and global vehicle manufacturers | [55,65] |
Energy Consumption | Climate control systems are energy-intensive, particularly in EVs, where they reduce driving range. Heat pumps are being explored as solutions. | Electric and hybrid vehicles | [55,60] |
Complex System Design | Modern systems integrate sensors, AI, and IoT, making them complex to design and maintain. | Connected and smart vehicle platforms | [61,62] |
Thermal Comfort Optimization | Achieving uniform comfort for all passengers in larger or variable-occupancy vehicles is technically challenging. | Buses, SUVs, and multi-zone passenger cars | [55,62] |
AI Integration | AI requires data collection and processing, increasing costs and raising privacy concerns. | AI-enabled vehicles | [59,60] |
High Development Costs | Transitioning to advanced systems, such as electric air conditioning units or low-GWP refrigerants, is expensive. | Automotive R&D and production sectors | [55,62] |
Retrofitting Costs | Upgrading older vehicles with modern systems is often prohibitively expensive. | Aftermarket services and older vehicle fleets | [55,64] |
Consumer Accessibility | Intelligent climate control systems remain unaffordable for many consumers, creating a market gap. | Mass-market vehicle segments | [66,67] |
Flammability of Refrigerants | Low-GWP refrigerants, such as HFO-1234yf, are mildly flammable, necessitating additional safety measures in vehicle design. | All platforms using mildly flammable refrigerants | [68,69,70,71,72] |
System Failures | Malfunctions in AI-driven systems can cause incorrect temperature readings or sensor failures, impacting safety. | Smart HVAC systems | [73,74] |
Dynamic Standards | Manufacturers must adapt to evolving refrigerant usage, energy efficiency standards, and emissions regulations. | Global OEMs and regulatory compliance teams | [75,76,77] |
Global Variability | Regional differences in standards challenge manufacturers to globally standardize systems. | Multinational vehicle production and distribution | [78] |
Lifecycle Impact | Climate systems’ manufacturing, operation, and recycling necessitate sustainable practices to minimize their environmental impact. | All vehicle platforms | [77] |
Battery Dependence in EVs | Climate systems in EVs heavily depend on battery power, demanding innovations to improve energy efficiency. | Electric vehicles | [79,80] |
Technology | Efficiency | Cost | Reliability | Environmental Impact | Key Challenges |
---|---|---|---|---|---|
Vapor Compression (VCR) | High efficiency; proven under diverse conditions | Moderate; supported by established infrastructure | High, mature, and widely adopted | Moderate to high, depending on refrigerant (e.g., HFC-134A vs. HFO-1234Yf) | Refrigerant GWP, energy consumption, system leaks |
Adsorption | Moderate; utilizes waste heat efficiently | High, bulky systems and low production scale | Moderate; fewer moving parts, longer lifecycle | Low; uses environmentally benign refrigerants (e.g., water) | Slower cooling rate, size constraints in compact vehicles |
Absorption | Moderate; effective when the heat source is available | Highly complex design and corrosive fluids | Moderate; dependent on continuous heat supply | Low; uses ammonia-water or lithium bromide | Safety concerns, integration with vehicle layout |
Thermoelectric | Low to moderate; limited by current material performance | High; relies on rare/expensive materials | High, solid-state system with no mechanical wear | Very low; no refrigerants used | Low cooling power, limited to niche use cases |
Magnetocaloric | Potentially high, promising in lab environments | Very high; experimental and costly technology | Undetermined; requires further long-term validation | Very low; solid-state and no harmful refrigerants | Material limitations, magnetic field generation complexity |
Technology | Efficiency | Cost | Environmental Friendliness | Safety |
---|---|---|---|---|
Vapor Compression (VCR) | High; proven across various climates and vehicle types | Moderate; widespread infrastructure | Variable; depends on refrigerant (HFC-134a high GWP vs. HFO-1234yf low GWP) | Generally safe; newer refrigerants may be mildly flammable |
Adsorption | Moderate; uses waste heat but has a slower response | High system size and complexity limit applications | High; uses natural refrigerants (e.g., water), low emissions | Very safe; no toxic or flammable substances |
Absorption | Moderate; effective with constant heat input | High; uses corrosive and potentially toxic fluids | Moderate; uses ammonia or lithium bromide | Risk of leakage; proper containment required |
Thermoelectric | Low to moderate; dependent on material properties | Highly expensive semiconductors | Excellent; no refrigerants used | Very safe; solid-state, no moving parts |
Magnetocaloric | Potentially high; still under experimental validation | Very high; rare materials and high production cost | Excellent; no refrigerants, zero direct emissions | Safe in principle; challenges with magnetic shielding and control |
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content. |
© 2025 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
Share and Cite
Sachelarie, D.; Achitei, G.; Munteanu, A.I.; Sachelarie, A.; Dontu, A.I.; Tcaciuc, G.D.; Popescu, A. Air Conditioning Systems in Vehicles: Approaches and Challenges. Sustainability 2025, 17, 5257. https://doi.org/10.3390/su17125257
Sachelarie D, Achitei G, Munteanu AI, Sachelarie A, Dontu AI, Tcaciuc GD, Popescu A. Air Conditioning Systems in Vehicles: Approaches and Challenges. Sustainability. 2025; 17(12):5257. https://doi.org/10.3390/su17125257
Chicago/Turabian StyleSachelarie, Daria, George Achitei, Andi Iulian Munteanu, Adrian Sachelarie, Andrei Ionut Dontu, Gabriel Dumitru Tcaciuc, and Aristotel Popescu. 2025. "Air Conditioning Systems in Vehicles: Approaches and Challenges" Sustainability 17, no. 12: 5257. https://doi.org/10.3390/su17125257
APA StyleSachelarie, D., Achitei, G., Munteanu, A. I., Sachelarie, A., Dontu, A. I., Tcaciuc, G. D., & Popescu, A. (2025). Air Conditioning Systems in Vehicles: Approaches and Challenges. Sustainability, 17(12), 5257. https://doi.org/10.3390/su17125257