Review of Researches on HVAC System Load on Electric Vehicles

International Journal of Applied Engineering Research and Development (IJAERD) ISSN (P): 2250–1584; ISSN (E): 2250–9383 Vol. 12, Issue 1, Jun 2022, 15–22 © TJPRC Pvt. Ltd.

REVIEW OF RESEARCHES ON HVAC SYSTEM LOAD ON ELECTRIC VEHICLES ELISH GANESH, YASHAS SHETTY, BIPIN WAIKHOM, C.M. VILAS & KIRAN C. H Department of Mechanical Engineering, Alva’s Institute of Engineering and Technology, Mijar, Moodbidri, DK- 574225, India ABSTRACT

In electric vehicles battery is utilize not only by the electric motor but also by another auxiliary components which enhance the safety and comfort of the vehicle. HVAC system which aids for thermal comfort. Electric vehicles are the best solution of environmental problems like greenhouse gas emission, air pollution and noise pollution. Electric vehicle’s range depends on the battery capacity. Comfort of Passengers has a significant impact on the battery pack of EVs and directly affect the range of the electric vehicles. The review work conducted highlights numerous variables that are taken into account while conducting the research works carried out by various authors. Thus, this paper mainly focuses on the parameters such as Impact of HVAC system on Electric Vehicles, External factors affecting the HVAC load and Range of the EV, Refrigerants used in HVAC system of electric vehicles and Range prediction and optimization. These parameters are one of the most prominent research areas in the background of the HVAC equipped system of EVs. KEYWORDS: Electric Vehicle, HVAC, Range prediction, Auxiliary conditions, Refrigerants

Received: Mar 10, 2022; Accepted: Mar 30, 2022; Published: Apr 22, 2022; Paper Id: IJAERDJUN20222

INTRODUCTION

Original Article

EVs. Through this article readers will be able to expand their knowledge in the field of electric vehicles as well as HVAC

The earlier generations of automobiles employed Air Conditioners. However, these air conditioners could just cool the cabin areas thus proving less useful on cold winter days. In order to overcome this shortcoming, HVAC was incorporated which not only was serviced as an Air Conditioner but also as a Heater. Thus, thermal comfort was ensured irrespective of the weather conditions. Additionally, HVAC systems also have functions such as defogging of the wind-shield, dehumidifying the cabin, purifying the cabin air, etc.

Heating Ventilation and Air Conditioning, abbreviated as HVAC is a unit that has many different components such as compressor, condenser, throttle valve, pressure regulating devices, etc. The unification of all these components provides thermal Comfort in the vehicle cabin. Thermal comfort can be defined as a human being’s thermal sensation of the surrounding environment, which expresses the level of satisfaction of the thermal environment. Unfavourable thermal conditions would have an adverse effect on an individual’s health. For comfortable of passenger, a comfortable temperature and constant fresh air is essential. And in order to fulfil this requirement, a well-performed HVAC system is vital.

Electric vehicles are introduced as the solution to environmental issues such as greenhouse gas emission, air pollution, and noise pollution. Electric vehicles would have never existed without the advancement of battery and power electronics design. However, the electric vehicles carriage new design challenges in terms of driving range and battery capacity which is restricted by the battery pack. The battery stress is significantly dependent on

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Elish Ganesh, Yashas Shetty, Bipin Waikhom, C.M. Vilas & Kiran C.H

the power consumption of the whole electric vehicle. Electric vehicle power consumption is not only limited to the electric motor but also to other auxiliary components in electric vehicles. The architecture design in Internal Combustion Engine (ICE) vehicles helps the HVAC system to use the heat generated from the engine for heating the cabin zone. Therefore, only fans can use energy to maintain the temperature of the cabin in cold weather. However, due to the structural differences between electric and internal engine vehicles, the HVAC system does not use the heat generated by the electric motor. This system requires more power from the heating coil to generate heat, which significantly increases the energy consumption of HVAC. Research background with regard to Electric Vehicles is very vast and it is an exponentially growing research topic as a switch to efficient EVs would be incentivised by various organisations especially the government. Hence, with the relevance of the title of this review article we have discretised the discussion into very fundamental areas of research.

Thus, a summary of researches conducted in the areas of impact of HVAC system on electric vehicles, range prediction and optimisation, external factors affecting the range and refrigerants used in the HVAC system of electric vehicles have been produced in this paper.

IMPACT OF HVAC SYSTEM ON ELECTRIC VEHICLES A vehicle equipped with ICE would dedicate most of its power towards the powertrain system and the remaining Auxiliary systems for instance wipers or navigation systems would run on a battery. Electric vehicles however do not have distinct sources for running auxiliary and powertrain systems simultaneously, both of them derive power from a single battery unit.

The HVAC unit, out of all auxiliary systems consumes a significant amount of energy in EVs. The research work carried out by Bellocchi et al.[1] assesses the variance and nonlinearities of the HVAC system load on the driving range of the EVs. The parameters that contributed toward the nonlinearities were mainly categorised into the Locations, Seasons and time of the day in Italy. The assessments of these parameters on the HVAC system conventional heat pump produced the result that the HVAC system derived about 38% of the total energy that was assigned for the traction of the vehicle. This reduction was then rectified numerically when they proposed the model that equips a regenerative heat exchanger. The rectification was seen when the driving range showed an increase in its value from 68km to 98km when the same nonlinear parameters were taken into account.

The influence of the HVAC system can be understood better using modelling software. MATLAB is a powerful simulation tool that can be applied on this area of research as it has various plugins that can help analyse literally anything.

Hence, Mebarki et al.[2] conducted a thorough analysis on Electric vehicle and HVAC system by employing the MATLAB Simulink environment. The methodologies applied mainly the simulation models of: 

Air-conditioning system



Vehicle without AC system



Vehicle with the AC system.

The simulation models accounted the results of the consumption of the battery pack of the EV w.r.t to variation in

the surrounding temperature. It was also advised that Li-ion batteries should be equipped and must be standardised in a vehicle as it offers efficient dynamic properties while running the propulsion and the HVAC systems concurrently.

However, efforts must be taken in order to reduce the auxiliary system load on electric vehicles.

Impact Factor (JCC): 6.3648

NAAS Rating: 2.88

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A driving cycle is a common representation of set of vehicle speed points versus time. It is used to assess fuel consumption and pollutants emissions of a vehicle in a normalized way, so that different vehicles can be compared. The driving cycle is performed on a chassis dynamometer, where tailpipes emissions of the vehicle are collected and analysed to assess the emissions rates. In electric vehicles a driving cycle is used to analyse battery state and energy consumption in Electric Vehicles. A drive cycle contains reference data. Minimum speed, 3-dimensional plots are maximum speed, average speed, Speed Acceleration Probability Distribution, and Speed Acceleration Frequency Distribution. The selected micro-trips can be used for the construction of drive cycles. In study conducted by Lee et al[3] effects of air conditioning (i.e., cooling and heating) on driving range were studied for various driving modes including UDDS, HWFET, and NEDC. Their experimental setup featured components such as Chassis Dynamometer (48” compact 4WD), dynamometer control cabinet and data analysing system. These components can be schematically shown in the figure.

Inference in their research conducted on the three driving cycles proposed that, UDDS driving range is 12.6% higher than HWFET and NEDC driving ranges, because EV's driving propulsion was created by electric motors. Also, A/C operating prevails considerable effects on driving range decrease. Reduction rate is 16.8% (149.3 → 124.4km) on UDDS and 12.3% (132.1 → 115.86km) on HWFET.

EXTERNAL FACTORS AFFECTING THE HVAC LOAD AND RANGE OF THE EV There are many external factors like ambient temperature, solar radiation, road grade, humidity, and so on which affect the HVAC system energy consumption for optimal thermal comfort. Many studies have proved that among all factors ambient temperature has the highest impact on HVAC power which in turn has impact in driving range.

Kai Luiet al. [4]concluded that ambient temperature affects energy consumption in electric vehicle due to output energy losses in electric motor and auxiliary loading. Among auxiliary loading they focused on HVAC system and state that if threshold value between ‘cold’ and ‘warm’ is distinguished then heating becomes unreasonable in the temperature range higher than threshold temperature and cooling becomes unreasonable in the temperature range lower than threshold temperature, therefore potential energy saving is feasible. It results that an average of 9.66% electric power will be saved by eradicating unreasonable vehicle auxiliary loads.

Kurt Kruppok et al. [5]simulated the 5-zone car cabin model under the influence of solar radiation and ambient temperature to conclude that heating takes longer than the cooling by HVAC system. Therefore, heating consumes more electric energy than cooling of the cabin.

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Elish Ganesh, Yashas Shetty, Bipin Waikhom, C.M. Vilas & Kiran C.H

REFRIGERANT USED IN HVAC SYSTEM OF ELECTRIC VEHICLES. Author

Objective/Aim

Methodology

Budi Santoso and D..P Tjahjana[6]

This paper aims to show the experimental results to replace HC-134a by HC134 mixture.

It was carried out experimentally by varying the condenser temperature between 30 °C to 50 °C.

J S. Brown et. al. [7]

This paper aims to find out the performance of R134a and CO2 which is used in air conditioning systems of various automobiles by using model (semitheoretical).

It is carried out by using simulations models.

NIST’s semi-vapour compression models (CYCLE 11.UA, CYCLE11UA-CO2) is used to carry out the experiment.

Prajitno et.al. [8]

The objective of this research is to analyse and find out the characteristics of refrigeration for different types of cooling loads.

It was carried out experimentally using a wagon car of Toyota, Toyota Vios 2013 in Heat and Mass Transfer Laboratory.

Brahim Mebarki et.al. [9]

Find out the power consumed by AC on EV run

by Li-ion battery and its effects.

This experiment is carried out by using MATLAB by considering different MATLAB environment.

Sizing of AC system and optimised the energy consumption for cabin cooling.

It uses SINDA/FLUINT, a mainly use tool for simulating a system which uses very complicated fluid system like automotive industry, aerospace industry etc.

This paper aims to analyse the how a refrigeration injection affects the performance of a system.

It is performed experimentally by building a ASHP test bench for electric vehicle. The temperature is varied between 20 C to 0 C to carry out the experiment.

Bongha Song, JiwonKwon,Yongsuk Kim[10]

FeiQina et. al.[11]

Impact Factor (JCC): 6.3648

Conclusion The experimental results shows that HC-134 has more refrigerating effect than HC134a.The COP of HC-134 is more than HC-134a by 36.42% and the results shows that HC134 energy factor is greater than that of HFC-134a by 3.78%.

From the results obtained show that the coefficient of performance of CO2 is lower than that of R134a, for a compressor having s speed of 1000 RPM the COP of CO2 which is at 21% at 32.2C reduced to 34% at 48.9C. In tropical areas when the speed of the compressor increases the effect of refrigeration, the working of compressor and the heat of the condenser also increase. COP is decreased due to the above changes.

Refrigeration characteristics is also influenced by external loads.

1.39KW of power which is almost equal to 7.93% of total power is forced to provide when a combined loading consisting of AC, rolling friction, direction of the road, drag, slope angle etc. which in turn increases the DOD. There is less effect of increasing temperature to the performance of Li-ion battery.

Increasing the compressor working power improves the cooling performance of the interior, which in turn effects the driving range. The results obtained shows that by increasing the working power of the compressor by 20% the driving range will be decreased by almost 3km.

From the results obtained it can be proved that when difference in temperature between the evaporator and the condenser is greater than 55C, injection of refrigerant can improve the capacity of heating.

NAAS Rating: 2.88

Review of Researches on HVAC System Load on Electric Vehicles

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The papers referred helps us in identifying and understand the effects of refrigerants use in HVAC system in electric vehicles. HVAC consumes a lot of energy from the battery of the EV and reduces performance to a great extent, from these papers we come to know what kind of refrigerant can be used to increase the performance and efficiency as well as decrease the pollution due to the emission of greenhouse gases from this system. Data regarding air conditioning sizing and the test of heat pump using different compressor to increase the efficiency can be obtained from some papers referred.

RANGE PREDICTION AND OPTIMIZATION Author Hatem Abdelaty and Moataz Mohamed[12]

Objective/Aim Estimation of energy consumption rates and validation using the Altoona’s test real-world data.

Methodology

MATLAB Simulink.

Mohammad Abdullah Al Faruque and Korosh Vatanpurvar [7].

Estimation of the driving behaviour in terms of future vehicle speeds that will be integrated into the EV battery optimization.

A distinction in Artificial Neural Networks (ANN) called Nonlinear Auto Regressive model with eXogenous inputs (NARX)

Ivan Cvok1 et al.

Design a control system which satisfies the HVAC requirements in Electric vehicles and validating the overall control system by simulation.

Software based simulation and modelling of HVAC and control systems related to it.

Maciej Gis et al.[14]

Determination of heating system efficiency.

Simulation and experimental validation.

Jari Vepsalmainen, et al.

To estimate variation of energy demand in wide range of indeterminate factors.

Modelling and simulation is done in MATLAB.

Conclusion The study shows a causal relationship between the transit network parameters and energy consumption with the use of multiple linear regression analysis.

The original setting mindful NARX model empowered assessment for as long as 30 seconds with <12% blunder (27% improvement) and further developed the control execution up to 82% of the most extreme ideal exhibition.

It concludes that it is possible to achieve favourable trade-off between thermal comfort and HVAC efficiency in optimisationbased feedback control strategy.

The results drawn out suggest the usage of a powerful Heat Pump which would not severely drop the performance in terms of the range of an electric vehicle.

The mean energy request was 1.20 kWh/km with a standard deviation of 0.32 kWh/km and on normal 28% of the active energy was recuperated through regenerative slowing down.

The papers referred helps us in predicting the range of the vehicles under the influence of external factors and climatic conditions affect. Electric vehicles usually have less range than advertised by the manufacturer. Hence available energy has to be utilised effectively to get better range. Each trip is unique and has changed energy loads in terms of drive cycle and other energy consumers. Besides all other loads, HVAC can be more energy consuming among auxiliary loads.

CONCLUSIONS In recent decades, Electric vehicles have been proved to be a hot topic that is discussed in almost every part of the world.

The world has seen the drawback IC engine equipped vehicles hence a shift to electric vehicles have been incentivised and developed. The research area with regard to electric vehicles have a broad background thus this review work focuses energy consumption factor by HVAC in EVs. Through this article, the readers will be familiarized to the numerous research work that have been conducted in www.tjprc.org

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Elish Ganesh, Yashas Shetty, Bipin Waikhom, C.M. Vilas & Kiran C.H

the field of HVAC system impact on electric vehicles. This paper narrows the approach by taking into account of impact of HVAC system on electric vehicles, range prediction and optimisation, external factors affecting the range and refrigerants used in the HVAC system.

In the future the parameters that lead to thermal comfort and range optimisation in an electric vehicle can be considered as an integral area where research and development would lead to an optimised electric vehicle.

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S. Bellocchi, G. Leo Guizzi, M. Manno, M. Salvatori, and A. Zaccagnini, “Reversible heat pump HVAC system with regenerative heat exchanger for electric vehicles: Analysis of its impact on driving range,” Applied Thermal Engineering, vol.

129, pp. 290–305, Jan. 2018, doi: 10.1016/j.applthermaleng.2017.10.020.

2.

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K. Liu, J. Wang, T. Yamamoto, and T. Morikawa, “Exploring the interactive effects of ambient temperature and vehicle auxiliary loads on electric vehicle energy consumption,” Applied Energy, vol. 227, pp. 324–331, Oct. 2018, doi: 10.1016/j.apenergy.2017.08.074.

5.

K. Kruppok, F. Claret, P. Neugebauer, R. Kriesten, and E. Sax, “Validation of a 5-zone-car-cabin model to predict the energy saving potentials of a battery electric vehicle’s HVAC system,” in IOP Conference Series: Materials Science and Engineering, Jul. 2018, vol. 383, no. 1. doi: 10.1088/1757-899X/383/1/012037.

6.

B. Santoso and D. D. D. P. Tjahjana, “Performance analysis of the electric vehicle air conditioner by replacing hydrocarbon refrigerant,” in AIP Conference Proceedings, Jan. 2017, vol. 1788. doi: 10.1063/1.4968268.

7.

J. S. Brown, S. F. Yana-Motta, and P. A. Domanski, “Comparitive analysis of an automotive air conditioning systems operating with CO 2 and R134a,” 2002. [Online]. Available: www.elsevier.com/locate/ijrefrig

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Prajitnoet al., “Cooling performance and evaluation of automotive refrigeration system for a passenger car,” in AIP Conference Proceedings, Jun. 2016, vol. 1737. doi: 10.1063/1.4949285.

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Mebarki, Brahim, et al. "Impact of the air-conditioning system on the power consumption of an electric vehicle powered by lithium-ion battery." Modelling and Simulation in Engineering 2013 (2013)

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11. F. Qin, Q. Xue, G. Zhang, H. Zou, and C. Tian, “Experimental Investigation on Heat Pump for Electric Vehicles with different Refrigerant Injection Compressors,” in Energy Procedia, 2015, vol. 75, pp. 1490–1495. doi: 10.1016/j.egypro.2015.07.281.

12. H. Abdelaty and M. Mohamed, “A prediction model for battery electric bus energy consumption in transit,” Energies, vol. 14, no. 10, May 2021, doi: 10.3390/en14102824.

13. I. Cvok, B. Škugor, and J. Deur, “Control trajectory optimisation and optimal control of an electric vehicle HVAC system for favourable efficiency and thermal comfort,” Optimization and Engineering, vol. 22, no. 1, pp. 83–102, Mar. 2021, doi: 10.1007/s11081-020-09515-w.

Impact Factor (JCC): 6.3648

NAAS Rating: 2.88

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14. M. Gis, P. Wiśniowski, and M. Bednarski, “Efficiency of electric vehicle interior heating systems at low ambient temperatures,” Open Engineering, vol. 11, no. 1, pp. 499–507, Jan. 2021, doi: 10.1515/eng-2021-0052.

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