Editing Heat exchanger (section)

==In aircraft==
In commercial aircraft heat exchangers are used to take heat from the engine's oil system to heat cold fuel.<ref>{{cite web| url = http://www.freepatentsonline.com/4498525.html |via=FPO | title = United States Patent 4498525, Fuel/oil heat exchange system for an engine| access-date = 3 February 2009| publisher = United States Patent and Trademark Office}}</ref> This improves fuel efficiency, as well as reduces the possibility of water entrapped in the fuel freezing in components.<ref name="2009-heat-exchanger">{{cite web| last=Croft| first=John|url = http://www.flightglobal.com/boeing-links-heathrow-atlanta-trent-895-engine-rollbacks/84936.article |date=3 February 2009 | title = Boeing links Heathrow, Atlanta Trent 895 engine rollbacks| access-date = 3 February 2009| publisher = Flight Global }}</ref>