Impact of fueling protocols on emission outcomes for residential wood-fired appliances

Figures & data

Table 1. Comparison of test methods for wood-fired central heaters used in U.S. regulations.

	US EPA Method 28WHH (US EPA 2019a)	US EPA Method 28 Partial Storage (US EPA 2019b)	ASTM E2618-13 (ASTM 2013)	CSA B415.1 (CSA 2015)	EN 303–5 (EN 2012)
Fuel Type	Crib or Pellet	Cordwood	Crib or Cordwood	Pellet, crib, and cordwood	Cordwood
Fuel Feed	Manual and Automatic	Manual and Automatic	Manual and Automatic	Manual and Automatic	Manual and Automatic
Applicable for Thermal Storage	No	Partial Storage	Cordwood only	No	No
Hot-to-Hot test	Yes	Partial	Yes, unless testing with full thermal storage	Yes	Yes
Measures Startup	No	Partial	No	No	No
Steady-state test	Yes	Yes	Yes	Yes	Yes
# Load Categories Assessed	4	2–4	4	3	1–2
Fuel Load Categories	<15%, 15–24%, 25–50%, and 100%	<15% and 100%, (15–24%, 25–50% are optional)	<15%, 15–24%, 25–50%, and 100%	<35%, 36–50%, 100%	30% (optional) and 100%
Method of Efficiency Determination	Thermal Output	Thermal Output	Thermal Output	SLM	Thermal Output
PM Measurement method	Dilution tunnel	Dilution tunnel	Dilution tunnel	Dilution tunnel	In stack, hot filter
PM measurement	Total PM	Total PM	Total PM	Total PM	Filterable PM
PM Emission Metric	Weighted average or individual run, lb/MMBtu output	Simple average, lb/MMBtu output	Weighted average or individual run, lb/MMBtu output	Simple average of test runs, lb/MMBtu output	Average two periods at max. load. mg/m^3
Wood Fuel Species	white or red oak	white or red oak	Any within specified density range of 0.60–0.73	Any within specified density range of 0.60–0.73	beech, birch, oak, spruce, or hornbeam
Moisture range (dry basis)	19–25%	19–25%	19–25%	18–28%	13.4–20%
Fuel Loading for handfed units (minimum)	10 lb/ft^3	10 lb/ft^3	10 lb/ft^3	10 lb/ft^3	Manufacturer’s Specifications
Upper size limit	350,000 Btu/hr	350,000 Btu/hr	NO – typical apps described	500,000 Btu/hr	500 kW (1.7 MMBtu/hr)

(Btu = British thermal unit)

Figure 1. Schematic of wood gasification boiler with thermal storage (Siegenthaler 2017).

Table 2. Summary of research plan.

	Series Name	# of Reps	Kindling volume	Main Load Volume	Kindling Fuel configuration	Main Fuel Load configuration
Impact of Kindling Configuration	Test Series 1: Kindling Configuration #1	5	10% of the total fuel charge	5 ft^3	BNL’s instructions	Random
	Test Series 1: Kindling Configuration #2	5	10% of the total fuel charge	5 ft^3	Manual version 1 instructions	Smallest to largest
	Test Series 1: Kindling Configuration #3	5	10% of total fuel charge	5 ft^3	Manual version 2 instructions	Smallest to largest
Kindling loading volume	Test Series 2: Reduced Fuel Piece	5	20% of the total fuel charge	5 ft^3	Manual version 2 instructions	Smallest to largest
Reduced Fuel Piece Size	Test Series 3: Increased Kindling	5	10% of the total fuel charge	5 ft^3	Manual version 2 instructions	Smallest to largest
Minimum Piece Size Only	Test Series 4: Minimum Piece Size Only	6	10% of the total fuel charge	5 ft^3	Manual version 2 instructions	Smallest to largest
Additional Startup Fuel	Test Series 5: Additional Startup Fuel	4	10 of the total fuel charge	5 ft^3	Manual version 2 instructions	Smallest to largest

Figure 2. Kindling configuration #1, #2, and #3.

Table 3. Results from test series #1.

Kindling Configuration		PM lb/MMBtu	Average CO%	PM g/hr.	PM g/hr. 1^st hour	PM g/hr. Steady- State
Kindling Configuration #1	Replicate 1	0.25	0.54	8.83	11.96	7.50
	Replicate 2	0.63	0.36	10.88	22.81	7.87
	Replicate 3	0.43	0.70	7.81*	17.11*	5.56
	Replicate 4	0.77	0.62	20.61	46.39	11.22
	Replicate 5	0.45	0.63	12.71	33.69	3.82
	Mean	0.51	0.57	12.17	26.39	7.19
	Std Dev	0.18	0.12	4.55	12.33	2.48
	%CV	39%	23%	42%	52%	39%
Kindling Configuration #2	Replicate 1	0.20	0.41	4.76	6.10	3.92
	Replicate 2	0.24	0.35	8.98	21.12	3.14
	Replicate 3	0.26	0.37	6.69	14.15	4.00
	Replicate 4	0.59	0.46	22.17	45.85	9.77
	Replicate 5	0.92	0.79	26.95	38.99	21.87
	Mean	0.44	0.48	13.91	25.24	8.54
	Std Dev	0.28	0.16	8.93	14.97	7.08
	%CV	70%	38%	72%	66%	93%
Kindling Configuration #3	Replicate 1	0.31	0.43	10.47	22.49	5.29
	Replicate 2	0.17	0.25	6.56**	14.30*	2.99
	Replicate 3	0.17	0.28	6.29	10.68	4.10
	Replicate 4	0.33	0.58	8.95	18.98	5.18
	Replicate 5	0.60	0.59	14.49	18.16	13.24
	Mean	0.32	0.42	9.15	16.92	6.16
	Std Dev	0.16	0.14	3.00	4.07	3.64
	%CV	56%	37%	39%	27%	66%

*Missing 10 minutes of startup data due to rapid TEOM filter loading

** Missing 7 minutes of startup data due to rapid TEOM filter loading

Figure 3. Real-time PM Emissions Series #1-configuration 1.

Figure 4. Real-time PM Emissions Series #1-configuration 2.

Figure 5. Real-time PM Emissions Series #1-configuration 3.

Figure 6. Real-time PM emissions test series #2.

Figure 7. CO profile Test Series #2.

Figure 8. Real-time PM emissions test series 3.

Figure 9. CO profile test series #3.

Table 4. Results from Test Series 2.

Run #	PM lb/MMBtu	Average CO%	PM g/hr.	PM g/hr. 1^st hour	PM g/hr. Steady- State
Replicate 1	0.10	0.33	3.51	6.41	2.34
Replicate 2	0.11	0.34	5.00	6.63	4.36
Replicate 3	0.08	0.17	3.04	2.58	3.14
Replicate 4	0.09	0.24	3.92	7.55	1.62
Replicate 5	0.11	0.20	4.26	7.60	2.34
Mean	0.10	0.26	3.95	6.15	2.76
Std. Dev	0.01	0.07	0.67	1.85	0.93
%CV	13%	30%	19%	34%	38%

Table 5. Results from test series 3.

Run #	PM lb/MMBtu	Average CO%	PM g/hr.	PM g/hr. 1^st hour	PM g/hr. Steady- State
Replicate 1	0.16	0.26	5.94	7.78	4.86
Replicate 2	0.09	0.50	3.56	5.71	2.58
Replicate 3	0.12	0.64	4.22	6.76	3.14
Replicate 4	0.10	0.71	4.00	6.73	2.63
Replicate 5	0.09	0.44	3.56	6.14	2.32
Mean	0.11	0.51	4.26	6.62	3.11
Std Deviation	0.03	0.16	0.88	0.7	0.92
%CV	26%	33%	23%	12%	33%

Table 6. Results for test series #4.

Minimum Piece Size	PM lb/MMBtu	Average CO%	PM g/hr.	PM g/hr. 1^st hour	PM g/hr. Steady- State
Replicate 1	0.85	0.84	28.69	41.98	21.07
Replicate 2	0.36	0.61	10.34	25.11	4.16
Replicate 3	0.11	0.43	4.06	5.95	3.06
Replicate 4	0.30	1.03	9.57	20.21	3.99
Replicate 5	0.86	0.96	21.49	27.3	18.86
Replicate 6	1.13	1.13	18.89	27.79	16.22
Mean	0.60	0.83	15.51	24.72	11.23
Std. Deviation	0.31	0.22	8.95	11.62	7.99
%CV	66%	32%	59%	47%	74%

Figure 10. Real-time PM emissions from Test Series 4.

Figure 11. Comparison of fuel shapes.

Figure 12. Real-time PM emissions from Test Series 5.

Table 7. Results for Test Series #5.

	PM lb/MMBtu	Average CO%	PM g/hr.	PM g/hr. 1^st hour	PM g/hr. Steady- State
Replicate 1	0.07	0.35	3.1	3.66	2.78
Replicate 2	0.08	0.35	3.3	4.17	2.89
Replicate 3	0.12	0.21	5.47	8.7	3.63
Replicate 4	0.22	0.27	7.55	7.47	7.58
Mean	0.12	0.29	5.37	6.00	4.22
Std. Deviation	0.07	0.13	2.53	3.068	2.44
%CV	56%	22%	41%	41%	54%

Figure 13. Test series summary – average PM rates per replicate.

Figure 14. CO and PM comparison among test series.

Table 8. Summary of test series results: PM, CO, and variability.

Test Series	PM Range	Average PM	PM %CV	PM Performance range	Average CO %	CO %CV
1–1	0.25–0.77	0.51	39	0.52	0.57	23
1–2	0.20–0.92	0.44	70	0.70	0.48	38
1–3	0.17–0.60	0.32	56	0.43	0.42	37
2	0.08–0.11	0.10	13	0.03	0.26	30
3	0.09–0.16	0.11	26	0.07	0.51	35
4	0.11–1.13	0.60	66	1.02	0.83	32
5	0.07–0.22	0.12	56	0.15	0.19	22

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Data availability statement

The data that support the findings of this study are available from NESCAUM upon reasonable request to NESCAUM’s Executive Director.