The reactors produce heat through nuclear fission which heats water. Every material reacts when it heats up or when it cools down. Water expands as it heats and contracts as it cools. The clamshell machine heats and cools the mold in the same chamber. Six contestants enter each heat, with one quarter-finalist emerging from each of the four heats. It can also be used as a temperature controller that either heats or cools. The hot gas quickly heats up the evaporator and defrosts it. Such usage referred to "latent heat of expansion" and several other related latent heats. This economizer heats up the water to its saturation temperature. Above this temperature gas heats up during Joule expansion. Solar energy heats up the water in the still. She also swam in the 100-meter freestyle heats. It heats tobacco at a lower temperature than traditional cigarettes. The ground then heats the air at the surface. The combustor then heats this air at constant pressure.