Text: 1. Fluids absorb heat while changing from a liquid state to a vapor state and give up heat in changing from a vapor to a liquid. 2. The temperature at which a change of state occurs is constant during the change provided the pressure remains constant. 3. Heat flows only from a body which is at a higher temperature to a body which is at a lower temperature (hot to cold). 4. Metallic parts of the evaporating and condensing units use metals which have a high heat conductivity (copper, brass, aluminum). 5. Heat energy and other forms of energy are interchangeable. For example, electricity may be converted to heat; heat to electrical energy; and heat to mechanical energy.

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