Commercial Electric Vehicle Cabin Heating System Modelling and Optimization

significantly affected by auxiliary energy demands such as cabin heating and window defrosting, which draw considerable power directly from the traction battery, thereby reducing the available driving range. Heat pump (HP) systems provide an energy-efficient alternative to resistive heating by utilizing recovered waste heat. However, their performance remains highly sensitive to the ambient conditions and the availability of recoverable heat, as well as the refrigerant properties and system control strategy, which govern the overall thermodynamic performance of the system. This study investigates the thermal management system of a heavy-duty commercial EV, focusing on improving heating efficiency through simulationbased optimization. A baseline HP system model was developed and validated in Simcenter Amesim using experimental vehicle data from an industry partner. Model parameters were calibrated through optimization studies to achieve close agreement between the simulated and experimental compressor power consumption and overall HP performance. Subsequently, the validated model was used to perform a series of simulation-based case studies assessing the effects of refrigerant selection, orifice diameter, and the addition of an internal heat exchanger on system performance. Results showed that replacing R134a with R1234yf yields comparable performance with only minor efficiency reductions, while offering substantial environmental benefits. The use of R744 demonstrated strong heating potential but would require a complete system redesign to accommodate transcritical operation. Optimization of the orifice diameter yielded an average system COP improvement of approximately 2 %, and the inclusion of an internal heat exchanger enhanced system performance by up to 10% in certain conditions. Across most cases smaller improvements of between 1-3% were observed. The findings highlight the effectiveness of simulation-driven design for advancing EV thermal management and demonstrate the value of componentlevel optimization in improving overall system performance. Through targeted design modifications, notable improvements in heating performance can be achieved, ultimately extending driving range and reducing energy consumption of the vehicle during cold-weather operation.

Grantor dc:publisher

Stellenbosch : Stellenbosch University

Year dc:date.issued

2026

Author dc:creator

• Mostert, Jacobus Christiaan

Advisors dc:contributor.advisor

• Owen, Mike T. F.
• Venter, Gerhardus

Language dc:language.iso

en

Repository record dc:identifier.uri

https://scholar.sun.ac.za/handle/10019.1/136141

OAI identifier oai:identifier

oai:scholar.sun.ac.za:10019.1/136141