Effect of Fuel Wobbe Number on Pollutant Emissions from Advanced Technology Residential Water Heaters: Results of Controlled Experiments

Technical Report · Tue Apr 01 04:00:00 EDT 2014

DOI:https://doi.org/10.2172/1131031· OSTI ID:1131031

Rapp, Vi H. ^[1]; Singer, Brett C. ^[1]

---

1. Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)

The research summarized in this report is part of a larger effort to evaluate the potential air quality impacts of using liquefied natural gas in California. A difference of potential importance between many liquefied natural gas blends and the natural gas blends that have been distributed in California in recent years is the higher Wobbe number of liquefied natural gas. Wobbe number is a measure of the energy delivery rate for appliances that use orifice- or pressure-based fuel metering. The effect of Wobbe number on pollutant emissions from residential water heaters was evaluated in controlled experiments. Experiments were conducted on eight storage water heaters, including five with “ultra low-NO_X” burners, and four on-demand (tankless) water heaters, all of which featured ultra low-NO_X burners. Pollutant emissions were quantified as air-free concentrations in the appliance flue and fuel-based emission factors in units of nanogram of pollutant emitter per joule of fuel energy consumed. Emissions were measured for carbon monoxide (CO), nitrogen oxides (NO_X), nitrogen oxide (NO), formaldehyde and acetaldehyde as the water heaters were operated through defined operating cycles using fuels with varying Wobbe number. The reference fuel was Northern California line gas with Wobbe number ranging from 1344 to 1365. Test fuels had Wobbe numbers of 1360, 1390 and 1420. The most prominent finding was an increase in NO_X emissions with increasing Wobbe number: all five of the ultra low-NO_X storage water heaters and two of the four ultra low-NO_X on-demand water heaters had statistically discernible (p<0.10) increases in NO_X with fuel Wobbe number. The largest percentage increases occurred for the ultra low-NO_X water heaters. There was a discernible change in CO emissions with Wobbe number for all four of the on-demand devices tested. The on-demand water heater with the highest CO emissions also had the largest CO increase with increasing fuel Wobbe number.

• Research Organization: Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES); USDOE Office of Energy Efficiency and Renewable Energy (EERE)
• DOE Contract Number: AC02-05CH11231
• OSTI ID: 1131031
• Report Number(s): LBNL--6626E
• Country of Publication: United States
• Language: English

Related Subjects

03 NATURAL GAS
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION