High-temperature jacket water

High-temperature jacket water is the closed fresh-water cooling circuit that takes heat directly from the cylinder liners, jackets, and cylinder heads of a marine diesel engine at roughly 85 to 90 degrees C outlet. The high temperature is held deliberately to limit thermal stress and cold-corrosion in the liners and to supply the fresh-water generator, which flashes seawater under vacuum using this waste heat. The circuit is cooled in a central cooler against the low-temperature fresh-water loop, with a coolant expansion tank for venting, make-up, and pump suction head.