Gas-fired adsorption heat pump water heater prototype.

Gas-fired adsorption heat pump water heater prototype.

Image: Oak Ridge National Laboratory

Lead Performer: Oak Ridge National Laboratory – Oak Ridge, TN
DOE Funding: $310,000
Project Term: October 1, 2013 – September 30, 2016
Funding Type: Annual Operating Plan (AOP)

PROJECT OBJECTIVE

The efficiency of residential natural gas water heating has plateaued at a primary energy factor (EF) of under 1.0, since best-in-class condensing water heaters cannot exceed this value. Two sorption cycles — absorption and adsorption — have the potential to push gas-fired storage water heater primary EF above 1.0 by pumping heat into the tank from the air surrounding the tank, in addition to depositing there the heat derived from combustion of natural gas. The objective of this project is to conduct an analytical and alpha lab prototype evaluation of adsorption technology to determine if there is a feasible path forward for development of a cost-effective adsorption heat pump water heater (HPWH).

An evaluation of different adsorbent and refrigerant pairs, adsorption cycle configurations, and materials will be initially conducted for applicability to the U.S. market. Assuming sufficiently promising (efficient and cost-competitive) options are identified, ORNL and a CRADA partner will collaborate to advance the development to a beta field test prototype evaluation stage. Although interim targets will be established, the ultimate performance and cost targets are a primary EF of ≥1.2 and an installed cost premium per first hour rating of ≤ $7.14/gal.

PROJECT IMPACT

Assuming project field test prototype(s) meets the performance and cost targets above, the CRADA partner would be encouraged to advance the development to a production model for the U.S. residential buildings market. Successful development will ensure market availability of efficient gas-fired adsorption HPWHs, which will not require hydrofluorocarbon (HFC) refrigerants that have significantly higher global warming potential than the refrigerants contemplated for use in the adsorption unit.

CONTACTS

DOE Technology Manager: Tony Bouza
Lead Performer: Moonis Ally, Oak Ridge National Laboratory