INNOTRANS: Adhesives and coatings specialist 3M has launched a new coating film aimed at reducing the effect of passive radiation on rolling stock roofs.
The 3M Cooling Film offers a high solar reflectance, deflecting or reflecting more than 85% of incoming solar radiation, and has a thermal emittance of around 91% to radiate absorbed heat away from the vehicle surface.
It has been developed to withstand harsh weather conditions including heavy rain or dusty environments, and has an easy-clean surface, which also helps to reduce maintenance costs. The ‘conformable’ film is designed to wrap around roof-mounted equipment boxes, avoiding the need to shield these with an additional panel and saving weight.
Early trials in a number of countries including South Korea, India, France and Spain have shown that the use of the cooling film can reduce vehicle interior temperatures by around 4.5°C compared to simply painting the roof panels white. This in turn is expected to reduce the cost of running onboard air-conditioning, which is becoming a significant factor as average global temperatures increase.
3M has also tested the film in non-rail applications, equipping a large fleet of electric last mile delivery vehicles in Arizona to improve driver working conditions. These vehicles absorb heat while standing at each delivery point, and air-conditioning is less effective when the vehicle doors are open.
‘Horizontal applications are really tough’, 3M’s rail portfolio leader Rohit Ramdey explained to Railway Gazette International, adding that ‘the harsher the environment, the better the film will work‘. The company is offering a five-year warranty for rail applications, but he says the life expectancy of the cooling film is at least seven to eight years. This would broadly match the heavy overhaul interval for modern rolling stock.
Source: rg