Hot and cold reservoirs

As mentioned in the “Classical heat engines” page, a heat engine converts heat into work. A simple heat engine interacts with a hot environment, also called a cold reservoir or cold bath, and a hot environment. Heat flows naturally from the hot reservoir to the cold. The engine extracts some of that heat and converts it into work. In the sculpture, the blue tank represents the cold reservoir, and the red tank represents the hot. The blue and red tubes illustrate the engines’ connections to the reservoirs.