The LO cooler construction is which type of heat exchanger?

• A. Plate and frame
• B. Air-cooled
• C. Fin-tube
• D. Shell and tube

Answer: (D)

The LO cooler in a gas turbine lubrication system is built as a shell-and-tube heat exchanger. This design handles the viscous, sometimes dirty lubricating oil and delivers reliable cooling for the oil by passing it through tubes (or around them) while a cooling fluid, typically water or glycol, flows on the shell side. The shell provides a large surface area and easy access for cleaning or descaling, and the tube side allows rugged handling of oil flow and pressure. This combination is ideal for large flow rates, varying fouling conditions, and the need for durable, maintainable cooling in the oil circuit. Plate-and-frame would be more for smaller, cleaner flows; air-cooled and fin-tube configurations are less practical for the heavy, oil-based cooling loop and require more space or less stable temperature control.