The Thermal Transfer Products BOL/BOLR series is designed for use under extreme thermal load conditions. Due to the excellent heat exchange performance and solid, lightweight and compact structure design, the difficulty in equipment cooling under extreme working conditions is solved and a stable heat exchange effect is achieved. This series can be equipped with a fan driven by the AC or hydraulic motor to meet different power requirements. It is also provided with a pressure bypass device so that the cooler can switch to the bypass mode rapidly upon cold startup, improving the equipment response speed and operation efficiency.