Hybrid Heat Pump Design and Application

The Hybrid Heat Pump (HHP) converts industrial waste heat into process steam. Waste heat at temperatures as low as approximately 200°F can be used. Steam output covers a range between 12,000 Ib/h and 50,000 Ib/h, depending on the application. The HHP functions by first using the waste heat to generate low-pressure steam and then to evaporate Freon. The Freon is the working fluid in an Organic Rankine Cycle (ORC) that provides power to a rotating shaft. The shaft drives a compressor used to boost the low-pressure steam to a pressure that makes it usable as process steam. An electric motor-generator is mounted on the same shaft and enables the HHP to function in a wide variety of operating modes. For instance, the HHP can function as a simple electric-driven heat pump during part of its operating cycle. It can also be operated in a cogeneration mode. This extreme flexibility allows the HHP to potentially achieve good economics in applications where other technologies are unattractive. This paper discusses technical and economic aspects of the HHP and is derived from a study funded by the Electric Power Research Institute (EPRI)