A shell and tube heat exchanger is a widely used heat transfer device that consists of a shell (outer vessel) containing a bundle of tubes through which one fluid flows while another fluid flows around the tubes within the shell. This design allows efficient heat exchange between the fluids without direct contact, making it ideal for applications in power plants, refineries, chemical processing, and HVAC systems. The exchanger can operate at high pressures and temperatures, with materials such as stainless steel, copper, or titanium ensuring durability and corrosion resistance. Proper maintenance, including regular cleaning to prevent fouling, is essential for optimal performance and longevity.