Antifreeze's a cryoprotectant used in internal combustion engines, and for many other heat transfer applications, such as HVAC chillers and solar water heaters. The purpose of antifreeze's to prevent a rigid enclosure from undergoing physical stresses and catastrophic deformation due to the expansion that occurs when water turns to ice. Compounds are added to the water to reduce the freezing point of the mixture below the lowest temperature that the system's likely to be exposed to, and to inhib… (More on Antifreeze)