MHI Develops Heat Recovery Type Centrifugal Heat Pump

In processes such as heating and sterilization by hot water immersion at food processing plants, cleansing in the production process of semiconductors and drying by heating during the painting processes, 80°C water is widely used. Generally, hot water is produced by oil- or gas-fired boilers which has heretofore been just disposed after use, or after being cooled by a cooling tower in some cases.

The "ETW" utilizes the thermal-energy of the wasted hot water to raise the temperature of used hot water, which was lost in the various processes, and enables the reheating of 75°C used hot water to 80°C. Specifically, the system uses the wasted hot water, with temperatures ranging from 35°C to 50°C, as heat-source water from which thermal energy is derived and supplied for reheating through heat pump mechanism. The system uses HFC-134a as a refrigerant. The heat pump system has two heat exchangers (evaporator and condenser), a centrifugal compressor and a motor to evaporate, compress and condense HFC-134a. The system uses an inverter speed control to minimize electric power consumption. In the standard model, the system is able to raise the temperature by 5°C.

As the system utilizes wasted hot water, it provides high energy-saving efficiency with COP (coefficient of performance)*1 4.5*2. By partially replacing the boilers in use with MHI 's new system, a considerable reduction of CO2 emissions and energy-savings become possible. Compared with an oil-fired through-flow boiler with the same heating capacity (one ton of steam per hour), the new MHI system is able to reduce CO2 emissions by maximum 74% and operational costs by maximum 65%.

Recently, with a view to realizing environmentally-friendly factories that leave no waste products, the need to reduce fossil fuel consumption by utilizing waste heat is increasing. Electricity providers are actively proposing electrification of all household energy needs to their customers. They are also focusing on further development of effective tools which can be proposed as solutions for "factory-electrification" to the industry. Responding to these needs and initiatives, MHI has entered into the industrial-use heat pump product field, combining its existing heating, air-conditioning and refrigeration technologies, including centrifugal compressors, inverters and high-temperature compliant designs. In marketing this system, MHI will collaborate with electricity providers and aggressively explore customer needs, including boiler replacement needs and support industrial efforts to reduce the burden to environment.