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An Integrated VRF System for Electric Bus HVAC and Battery Thermal Management

Presented at 14th International Conference on Internal Combustion Engines & Oil.

Paper id: ICICE&O14-1428

Heating, Ventilation, and Air Conditioning (HVAC) systems are a major contributor to energy consumption in electric buses, substantially affecting their driving range, especially under extreme weather conditions. Effective thermal management of the battery is also essential to prolong battery lifespan in electric vehicles. This paper presents a dynamic simulation of an integrated Variable Refrigerant Flow (VRF) system that simultaneously manages the thermal needs of both the passenger cabin and the battery pack. Developed in Python using the "CoolProp" library, the model is benchmarked against conventional air conditioning and Positive Temperature Coefficient (PTC) heating systems. Weather data from the "Meteonorm" library for Tehran’s summer, winter, and autumn conditions are used in three 24-hour scenarios. Results show significant efficiency improvements, with the VRF system reducing energy consumption by 34% compared to PTC heating during winter heating demand, while continuously managing battery thermal regulation. Moreover, in balanced conditions requiring simultaneous cabin heating and battery cooling, the system’s heat recovery mode achieved a notable average Coefficient of Performance (COP) of 7.01. These energy savings translate into practical benefits, extending the vehicle’s daily range by about 18 km during winter.

Authors 

Morteza Nejatian, BSc

MSc Student, School of Mechanical Engineering, University of Tehran

Behrang Sajadi, PhD

Associate Professor, School of Mechanical Engineering, University of Tehran

Vahid Esfahanian, PhD

Professor, Department of Mechanical Engineering, University of Tehran, and Head of the Vehicle, Fuel and Environment Research Institute (VFERI).

About me

Coming from a family of engineers, my path felt both natural and deeply personal. As a second-generation mechanical engineer, I was raised with an innate curiosity for how things work. This heritage instilled in me a core belief: that the most advanced solution is often the simplest one. My approach is grounded in this principle of elegant simplicity, seeking to refine complex systems not by adding more, but by designing with greater clarity and purpose.

At heart, I am a builder and a problem-solver, driven by the challenge of optimizing for a more efficient and sustainable future. My passion lies in contributing to technologies that work in greater harmony with our world, believing that even the smallest, well-considered improvement can lead to significant and lasting change.

Contact me:
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Conference: 14th International Conference on Internal Combustion Engines & Oil

Location: Niroo Research Institute (NRI), Tehran, Iran

Date: October 21-23, 2025

Official Website: www.iranengine.com