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Nissan testing paint that keeps cars cooler

Nissan has been testing out an innovative automotive paint aimed at helping lower a vehicle's ambient cabin temperature in summer and reducing the energy usage of the air-conditioning system. Developed in partnership with Malaysian-based company Radi-Cool, a specialist in radiative cooling products, the paint incorporates metamaterials, which are synthetic composite materials with structures that exhibit properties not usually found in nature.

Nissan began a 12-month feasibility trial of the paint in November 2023 at Tokyo International Air Terminal at Haneda. In collaboration with Japan Airport Terminal Co. and All Nippon Airways, Nissan's cool paint was applied to a Nissan NV100 service vehicle operated by All Nippon Airways airport services.

With its large, open tarmac, Haneda airport has been providing the perfect environment to conduct real-world evaluation of the paint's performance under exposed, high-temperature, real-world conditions. Although still in the testing phase, the results to date have been impressive. Parked side by side under the sun, a vehicle treated with the cool paint technology has demonstrated up to a 21.6-degree F reduction in exterior surface temperatures and up to 9-degree F cooler interior, compared to a vehicle featuring traditional automotive paint.

The cooling paint has so far showed a more than 20-degree reduction in vehicle surface temperature and almost 10 degrees cooler inside. [Image courtesy of Nissan]

 

 

The paint's cooling performance has been particularly noticeable when the vehicle is parked in the sun for an extended period. A cooler cabin is not only more pleasant to enter, but also requires less air-conditioning run-time to cool the cabin to a comfortable temperature. This helps reduce load to the engine, or in the case of an electric vehicle, draw on the battery. It's also not as harsh when entering the vehicle.

The metamaterial embedded within the cool paint features two microstructure particles that react with light. One particle reflects near-infrared rays in the sunlight that would typically cause molecular-level vibrations within the resin of traditional paint to produce heat. The second particle enables the real breakthrough. It creates electromagnetic waves that counteract the sun's rays, redirecting the energy away from the vehicle into the atmosphere. Combined, the particles in Nissan's cool paint reduce the transfer of heat into surfaces such as the roof, hood, doors, and panels.

VIDEO: Nissan cool paint technology: An innovative way to beat the heat. [Credit: Nissan]

Development lead Dr. Susumu Miura, senior manager and expert at the Advanced Materials and Processing Laboratory in Nissan Research Center, has dedicated much of his career at the world-wide car manufacturer to exploring ways to make cars quieter, cooler, and more efficient. He played an important role in developing Nissan's award-winning noise-reducing acoustic material.

While radiant cooling paint isn't new, it is typically used for buildings and structures. It's often very thick, requiring application by a paint roller. Devoid of any clear topcoat, it can leave a chalky residue when touched.

Key challenges Miura has had to consider when developing an automotive version of the cooling paint tech included ensuring it could incorporate a clear topcoat, that it could be applied via a spray gun (not a roller), and it could meet Nissan's rigorous internal standards for paint quality.

Miura and his team have tested over 100 samples and are currently evaluating a thickness of 120 microns, approximately six times thicker than typical automotive paint. They have confirmed resistance to salt and chipping, peeling, scratches, and chemical reactions, along with color consistency and repairability. As development progresses, Miura and his team are continuing to explore thinner options that deliver the same level of cooling performance.

While the testing and development is ongoing, Miura and his team hope the paint can one day be offered for special orders and in a variety of colors. Miura sees strong potential, particularly for light commercial vehicle applications such as vans, trucks, and ambulances that spend most of the day out driving.

Source: Nissan

Published August 2024

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