A new material technology has been developed that improves the problems of existing materials in radiant heating systems used to save energy in electric vehicles, and it is expected to be widely used in the manufacturing sector, including automobiles and semiconductors, in the future.

The Korea Electrotechnology Research Institute (KERI) announced on the 14th that Dr. Dong-Yoon Lee's team at the Electric Conversion Materials Research Center developed a high-efficiency, high-flexibility 'metal fiber cloth surface heating element' technology that can complement the shortcomings of electric vehicles that are vulnerable to the cold.

In winter, battery performance often declines and energy consumption increases due to vehicle interior temperature control, which reduces the electric vehicle's fuel efficiency (mileage per kWh).

The U.S. Environmental Protection Agency (EPA) also announced that in an environment of -7 degrees Celsius, electric vehicles' fuel efficiency dropped by 34% and their driving distance was reduced by 57% compared to room temperature (24 degrees Celsius).

One of the most frequently considered factors in improving electric vehicle performance is the thermal management system.

Internal combustion locomotives can use the engine's waste heat as a heat source to control the interior temperature, such as for heating.

On the other hand, electric vehicles lack waste heat, so they require separate systems for heaters and other devices, which often leads to reduced driving range.

To this end, many researchers are working to reduce the waste generated by electric vehicles’ electrical devices.Heat is lost Typically, about 20% of the electrical energy is lost as heat energy during the power transmission process of electric vehicles.

Therefore, the biggest challenge for electric vehicles is trying to improve energy efficiency by managing and utilizing wasted heat.

Among them, the 'radiant heating system', which was proposed as a goal by a leading domestic automobile group with inspiration from the traditional ondol method, is a technology that is expected to greatly contribute to energy saving in electric vehicles by applying a 'heating element' that generates heat when receiving electricity to the interior area of the vehicle.

Compared to existing heating methods, this system reduces energy consumption required to reach the appropriate temperature while providing a longer-lasting heat retention effect, which can solve the problem of shortened driving distances for electric vehicles in winter.

Currently, a 'PTC (overcurrent protection device)' is used as a heating element, which has the advantages of rapid heating, overheating prevention through its own temperature control function, and miniaturization and low noise.

On the other hand, because it is large, heavy, and consumes high power, it is difficult to apply it to electric vehicles.

To replace this, heating elements using heating wires or carbon have been proposed, but they are not sufficient alternatives due to low thermal efficiency or risk of fire.

Accordingly, Dr. Lee Dong-yoon's team at KERI utilized the know-how from the past development of fabric-type solar cells and heating clothing technology to present the 'metal fiber cloth surface heating element' technology.

The technology begins with a loom that weaves fabric by interweaving threads lengthwise and crosswise.

We make fabric by weaving very thin 'stainless steel micro wire (SUS316L)' of 50μm (less than half the thickness of a human hair) that boasts high thermal conductivity and durability, and this can be applied as a heating element.It is a structure that applies a combination of rock-solid technology (insulating layer and electrode configuration, etc.). And when electricity is passed through it, the internal resistance of the metal causes heat generation of up to 500 degrees.

Since the metal fiber cloth has a wide space shape rather than a line, it shows an even temperature distribution in terms of heating function, and it is also flexible, so it can be easily attached to any curved surface inside the vehicle.

In addition, when the same amount of electricity is passed through the heating element, the metal fiber cloth shows 10-30% higher heating performance than the existing heating wire method, showing superior efficiency. Above all, due to the characteristics of the fiber cloth, it has the great advantage of maintaining performance and stably generating heat even if a short circuit or partial damage occurs during use.

With these many advantages, KERI's metal fiber cloth heating element is considered the optimal technology to realize the ondol-type floor heating for electric vehicles. It provides comfort by warming a wide space with radiant heat rather than using air heating, which dries out the interior when used for a long time.

In addition, it is an all-round technology that can be applied to many industries that require uniform heat generation, such as manufacturing (semiconductor production equipment, chemical plant piping, machine heating devices, etc.), daily life (massage chairs, electric blankets, leisure heaters), medical, and military use, so its possibilities are endless.

The research team estimates that companies in these fields will be able to achieve energy savings of 10-30% by utilizing metal fiber surface heating elements.

KERI's Dr. Lee Dong-yoon said, "Unlike thread, metal fibers are stiff and very difficult to weave. However, in collaboration with Songi Industry Co., Ltd., a textile production and processing company, we were able to develop a metal fiber-specific loom and weaving pattern after much effort." He continued, "This is the world's first time that a cotton-shaped heating element has been produced using only metal fibers. Through our achievement, we can expect to reduce companies' energy costs and achieve carbon neutrality nationwide."

KERI, which has completed patent application, has completed performance verification, including passing the standardization test of metal fiber cloth surface heating element for the top semiconductor companies in Korea. Currently, five technology transfers have been completed, and the goal is to discover additional companies in demand for electric vehicles and semiconductors and promote prototype production and technology transfer.