On passage through an expansion valve adiabatic The warm gas flows through a heat into a region of expansion House lower pressure, the Outside nside exchanger where it High pressure liquid expands into a is cooled by a flow liquid(-70°F of room t air and gas, becoming very much colder condensed to a Expansion liquid, thus giving Low pressure(-10F) up heat to the room Cold Fan air Heat exchanger Heat exchange (evaporator) The extremely cold gas Compressor flows through a second Freon gas is heat exchanger where it Low pressure gh pr essure gas(-40°F) gas(-100°F ompressed by a is warmed to the outside compressor to air T, thus extracting heat Electric raise its T and P from the outside air ★ Figure 3. 12 An electrically driven heat pump using Freon as a working fluidFigure 3.12 An electrically driven heat pump using Freon as a working fluid. Freon gas is compressed by a compressor to raise its T and P. The warm gas flows through a heat exchanger where it is cooled by a flow of room T air and condensed to a liquid, thus giving up heat to the room. On passage through an expansion valve into a region of lower pressure, the liquid expands into a gas, becoming very much colder. The extremely cold gas flows through a second heat exchanger where it is warmed to the outside air T, thus extracting heat from the outside air. adiabatic expansion