How Does a Heat Exchanger Work?

Heat exchangers are found everywhere — in car radiators, power plants, HVAC systems, and refrigerators. The simplest type is a shell-and-tube exchanger: one fluid flows through inner tubes while another flows around them inside an outer shell. Heat conducts through the tube walls from the hotter fluid to the cooler one. Plate heat exchangers use corrugated metal plates stacked together with alternating fluid channels, providing a large surface area in a compact space. Counter-flow arrangements (fluids moving in opposite directions) are more efficient than parallel-flow because they maintain a larger temperature difference along the length. Efficiency depends on surface area, flow rates, and the thermal conductivity of materials used.