Along with the stricter regulations on refrigerants and the enforcement of the Law Concerning the Discharge and Control of Fluorocarbons for the purpose of preventing global warming, the need for low-GWP refrigerant (non-CFC) chillers has been increasing. On the other hand, in process cooling systems at food factories where chillers are used, excessive starts and stops of chillers sometimes occur because the chillers cannot follow the load variation in batch operations in which the load changes abruptly in a short time. Mitsubishi Heavy Industries Thermal Systems, Ltd. introduced a two-stage cooling system using temperature difference for which the variable speed centrifugal chiller operating at ultra-low load was adopted, an exhaust heat recovery (hot water supply) system and other technologies to promote the delivery of high-efficiency systems that allow stable continuous operation at varying loads.