A system comprises a heat source. The system also comprises a bladder comprising opposing thin-walled sheets and a fluid flow conduit defined between the opposing thin-walled sheets. The fluid flow conduit comprises an inlet and an outlet. The system further comprises a first fluid line coupled to the heat source and the inlet of the bladder. The system additionally comprises a second fluid line coupled to the heat source and the outlet of the bladder. The system also comprises fluid flowable through the first fluid line from the heat source to the inlet, from the inlet through the fluid flow conduit to the outlet, and through the second fluid line from the outlet to the heat source.