A U-tube heat exchanger is a common shell-and-tube device named for its U-shaped tube bundle, widely used in chemical, petroleum, and energy industries. It consists of U-tubes, a shell, and tube sheets, with hot fluid flowing inside the tubes and cold fluid in the shell, facilitating heat transfer. The U-shape allows tubes to expand freely, accommodating high temperatures and pressures while reducing thermal stress. Advantages include simple design, easy maintenance, and high heat transfer efficiency, ideal for clean or moderately corrosive fluids. However, tube cleaning is challenging, and it requires more space. U-tube heat exchangers excel in steam condensation and liquid heating processes.