Ammonia is a commonly used industrial coolant. Goodyear uses three ammonia heat exchangers in its production process lines. The ammonia cooling system supplies the heat exchangers with pressurized liquid ammonia. As the ammonia absorbs heat from the process chemical flowing through tubes in the center of the heat exchanger, the ammonia boils in the heat exchanger shell
(Figure 2). A pressure control valve in the vapor return line maintains ammonia pressure at 150 psig in the heat exchanger. Ammonia vapor returns to the ammonia cooling system where it is pressurized and cooled, liquefying the ammonia