Final answer:
A heat exchanger is used to transfer heat energy between two fluids without direct contact, crucial in systems like forced-air furnaces.
Step-by-step explanation:
A device used to transfer heat energy from one fluid to another without direct contact is called a heat exchanger. Heat exchangers are commonly used in various applications such as refrigeration, air conditioning systems, and even complex power plants. By allowing heat to transfer from one fluid to another without the two fluids mixing, these devices can efficiently manage temperature and energy flow within systems. For example, in a forced-air furnace, heat exchangers are crucial for transferring the heat generated by the furnace into the air that is then circulated throughout a home.