U.S. patent application 20180340740 (applicant BorgWarner Inc., Auburn Hills, Mich.):
"A number of variations may include a vehicle system which includes an engine. The vehicle system may also include a phase change material which may be disposed in a phase change material device. The phase change material may be released into a vehicle cooling system upon user command. The PCM device may be constructed and arranged to increase a temperature of a vehicle cabin without the engine being turned on when the phase change material is released."