Evaporative Cooling of Water
First, use the slider to select the mass of water to evaporate. Then, clicking the play button turns on a vacuum pump that removes water vapor from a well-insulated tank that initially contains 10 kg of liquid water at 40°C. Water evaporates because the pump decreases the water partial pressure below its saturation pressure. The energy to evaporate water is obtained by cooling the remaining liquid water, and then freezing some of the liquid when the temperature reaches 0°C. The bar graph on the right shows the amounts of liquid and solid water in the tank and the amount of vapor that evaporated. In the tank, the remaining liquid is blue and the solid is green. The amounts of each phase are determined using unsteady-state mass and energy balances.

Download the CDF file to view the simulation using the free Wolfram CDF player.