An apparatus for heat transfer includes a device and a mechanism for transferring heat to or from the device. The mechanism for transferring heat includes a working fluid that includes a hexafluoropropylene trimer having Structural Formula (1) The hexafluoropropylene trimer having Structural Formula (1) is present in the working fluid in an amount of at least 85% by weight, based on the total weight of hexafluoropropylene trimer in the working fluid.