Energy, fuels, and chemicals 3197 



extra turbulence and burning time for the volatiles, and the baffle also helps to 

 increase heat transfer from the hot gases to the outside of the stove. Wood tends 

 to bum from the front of the stove to the back. These stoves are noted for 

 steadiness of heat output and high efficiency. Common examples of this type of 

 stove are the Norwegian J(t)tul, Lange, and Ram woodstoves.^ 



Economics. — The economics of home heating are attractive if an efficient 

 wood stove is used. Lew^ has estimated that one cord of red oak (21 million 

 Btu's per cord) burned in an airtight stove (50 percent efficiency) will yield heat 

 equivalent to the use of 1 . 1 tons of coal ,115 gallons of number 2 fuel oil , 1 4 ,000 

 cubic feet of natural gas, or 3,074 kilowatt hours (kWh) of electricity. At 6^ per 

 kWh, the equivalent electricity cost would be $ 1 84. A cord burned in a box stove 

 or Franklin fireplace (30 percent efficiency) would produce heat equivalent to 

 1 ,848 kWh or $1 1 1 . In a fireplace with 10 percent efficiency, the heat realized 

 would be equivalent to only 616 kWh, or about $37 per cord. It is thus apparent 

 that savings will depend greatly on the efficiency of the burning system. Parker 

 (1979) provided graphs for quick analysis of wood costs related to costs of fossil 

 fuels or electric heat at various stove efficiencies. 



Air pollution and trends. — Air-tight stoves that restrict inlet air to increase 

 stove efficiency are now widely used in northern parts of the United States. 

 When such stoves are operated with dampers nearly closed, particulate and 

 condensable organic emissions can signifiantly contribute to national pollutant 

 emissions (Butcher and Sorenson 1979; DeAngelis et al. 1980; Jaasma and 

 Kurstedt^). When stove fires are burned hot with ample combustion air, pollu- 

 tion is lessened as is accumulation of condensed creosote in chimneys. 



Installation of a catalytic combustor may increase stove efficiency and de- 

 crease both pollution and creosote buildup by burning, rather than discharging to 

 the chimney, combustible gases distilled from the wood being burned. Gases 

 coming in contact with a catalytic combustor bum even if the temperature of the 

 gases is below 500°F. As made by Corning Glass Works, the device is a ceramic 

 honeycomb 3 inches long by 5Vh inches in diameter with 16 cells per square inch 

 coated with a noble metal similar to the catalysts used in automative exhaust 

 systems. Temperatures as high as 1 ,600°F can occur in a catalytic combustor, so 

 it should be located inside the stove where the gases must pass through it.*^ Quick 

 fouling of catalytic combustors and resulting short service life is a problem not 

 yet fully solved by stove designers. 



V. Lew, "Wood Burning Stoves", a staff report to the Fuels Office, Alternatives Division, 

 California Energy Commission, June 14, 1978, Sacramento, California) 



^Jaasma, D.R., and H.A. Kurstedt, Jr. (n.d.) The contribution of wood combustion to national 

 pollutant emissions. Unpublished paper. Dept. Mechanical Eng., Virginia Polytech. Inst, and State 

 Univ., Blacksburg. 



^Personal communication from D.E. Nelson, U.S. Dep. Agric, Washington, D.C., May 1981 . 



