How does a heat exchanger transfer energy in a binary cycle power plant?

In a binary cycle power plant, the heat exchanger serves as the critical interface for energy transfer between two separate fluid loops. Geothermally heated water is drawn from the ground through one set of pipes, while a secondary working fluid—typically a substance with a low boiling point, such as ammonia or certain hydrocarbons—circulates within a closed loop.1

The heat exchanger facilitates the transfer of thermal energy from the hot geothermal water to the cooler working fluid through a dividing wall, utilizing the principle that heat naturally flows from higher to lower temperatures. As the working fluid absorbs this energy, it vaporizes. This high-pressure vapor is then directed to drive a turbine connected to an electrical generator. Once the vapor passes through the turbine, it is recondensed and cycled back to the heat exchanger to repeat the process, ensuring the geothermal fluid remains isolated from the power-generating loop.12