Hyundai and Kia have revealed the details of their new heat pump system designed to maximize the range of EV drives at low temperatures. The automakers say the heat pump maximizes the distance that EVs can travel by scavenging waste heat to warm the cabin on a single charge.
In 2014, the original technology was introduced on the first-generation Kia Soul EV. Comprising a compressor, evaporator and condenser, the heat pump captured waste heat from the electrical components of the vehicle, recycling this energy for heating the cabin.
The new device is scavenging waste heat from an increasing range of sources, including drive engines, on-board chargers, inverters, battery packs and sluggish chargers. The heat produced by these components is used to vaporize from liquid to gas-phase refrigerant. High-pressure gas is discharged from the compressor and forced into a condenser where it is converted to liquid again. This process generates additional heat energy that is recovered by the heat pump and used to warm the cabin, reducing the load on the battery system.
The Norwegian Automotive Federation (NAF) recently compared 20 EVs to identify models with the most consistent driving range and charging performance in cold and warm weather conditions. The test measured each vehicle’s output variance in cold conditions as opposed to the figures quoted by the manufacturer. First position was taken by the Hyundai Kona Electric, which uses the latest heat pump technology, moving 405 km in the cold compared to the theoretical 449 km under combined cycle test conditions (23 ° C/73 ° F). The Kona Electric provided 91 per cent of its nominal range in extremely cold weather.
Hyundai and Kia say their water-cooling system for the battery pack provides more improvements in range without rising physical dimensions. EV battery cells can be more tightly packaged as water-cooling channels take up less space than air-cooling channels, increasing battery density by up to 35 per cent.
A study on the Hyundai Kona Electric and Kia Niro EV carried out by Korea’s Ministry of the Environment found that the heat pump significantly reduced battery consumption in cold conditions. When each car was driven with the HVAC system activated at temperatures of -7 ° C (19 ° F), they were able to maintain 90 per cent of their driving range compared to 26 ° C (79 ° F) ambient journeys undertaken at an ambient 26° C (79° F)