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Uni claims microwave HVAC tech can boost EV range

Researchers at the University of Birmingham in the UK are working on a patent-pending microwave-based thermochemical HVAC system that could enhance the battery range of electric vehicles by up to 70 per cent.

Conceived by research lead Professor Yongliang Li in pursuit of zero-carbon technologies, the e-Thermal bank system combines a chemical heat pump with microwave energy to provide cabin temperature control. 

Professor Yongliang Li

This groundbreaking approach shifts the burden of HVAC functions away from the battery, where a reduction of up to 40 per cent in range can occur in extreme temperature conditions. 

“Heating and cooling the EV cabin requires considerable energy and is the most significant contributor to EV range reduction,” said Professor Li.

Through reversible chemisorption, the e-Thermal bank generates simultaneous heat and cooling, offering a comprehensive solution for maintaining optimal cabin temperatures in electric vehicles that can be conveniently charged using existing EV battery infrastructure. 

When charging, the system uses microwave energy to separate a solid-vapour working pair and convert the resulting vapour into liquid form, effectively storing this energy within the vehicle’s e-Thermal bank, ready to power HVAC functions. 

During the discharge process, the stored energy is released as required by directing the vapour into a reactor to generate heat through an exothermic reaction. At the same time, an evaporator triggers a phase change from liquid to gas, resulting in a cooling effect.

“We aimed to offload these thermal management tasks to a microwave-driven process,” explained Professor Li.

“Microwave is a fast heating method because microwaves penetrate uniformly through materials and so deliver energy evenly into the body of the material. The energy cost can be minimised by coupling with a smart meter to charge the system when energy is cheap, and the stored energy can then be used at any time.”

This innovative thermochemical system is reported to have a remarkable energy density of 1600Wh/kg, well exceeding the average density of approximately 700Wh/kg from lithium-ion batteries.

Professor Li anticipates that “by replacing conventional HVAC and possibly a small portion of the battery pack, e-Thermal banks would provide efficient cabin temperature control and a range extension of up to 70 per cent, at a lower cost than increasing battery capacity”.

Aimed at improving EV performance through affordable solutions that prolong battery life, boost driving range, and elevate cabin comfort, this novel system holds further promise beyond the automotive industry.

Its versatility extends to applications such as mobile heating and cooling devices, as well as providing thermal support in industrial settings, offering exciting low-carbon opportunities for future applications across different sectors.

Supported by the Engineering and Physical Sciences Research Council (EPSRC) and with a patent application in progress through the University of Birmingham Enterprise, the developers of the e-Thermal bank system are actively seeking commercial partners for licensing, collaboration, and co-development opportunities.

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