Paper No 660 – Development of a Novel Sorption-Type Heat Pump Water Heater for North American Homes – 14th IEA Heat Pump Conference, Chicago, USA
Critical to decarbonizing gas-fired water heating, typically up to 26 GJ of natural gas consumed per home per year, is advancing heat pump water heaters (HPWHs). This paper provides an overview of the development and experimental demonstration of this novel sorption-type HPWH, using a nested buffer tank/heat exchanger approach driven by an integrated compact steam boiler. Led by a European technology developer with technology support from multiple U.S.-based partners, this fuel-fired HPWH concept is intended for North American homes, with a hybrid design of both up to 2 kW peak output from the sorption modules and up to 12 kW peak auxiliary output from the steam boiler. With an efficiency target of =1.25 UEF and a target first hour rating of 284 L of hot water, this paper focuses on several aspects of this product development and testing, including a) the development and testing of a compact steam boiler loop to drive the desorption process, designed for 14 ng NOx/J output and compatible with up to a 30% hydrogen/natural gas blended fuel, b) immersed sorption modules within the buffer storage tank for water heating with a COPgas > 1.40 using limited moving parts, and c) heat exchange and preliminary system controls, per empirically-calibrated simulation, to meet UEF targets and high usage hot water patterns typical for 4-5 occupant homes. Following this review of testing results, the authors provide an outlook for fuel-fired HPWHs in a rapidly decarbonizing North American market.