Development of an integrated duty cycle test method to assess cordwood stove performance

Figures & data

Table 1. Morin IDC Stove Paper Tables Cordwood stoves in initial research program.

Stove #	Construction Type	Firebox Size cubic feet (ft^3)	Air Controls	Emission Controls	EPA 2015 NSPS Certification
1	High mass	3.1 ft^3 – Large	Variable	Non-catalytic tube	Step 1
2	Steel	1.3 ft^3 – Small	Variable	Catalytic	Step 2 Prototype
3	Steel	3.2 ft^3 – Large	Variable	Catalytic	Step 1
4	Cast iron	0.8 ft^3 – Small	Variable	Non-catalytic tube	Step 1
5	Cast iron	2.1 ft^3 – Medium	Variable	Non-catalytic non-tube	Step 1
6	Steel	2.2 ft^3 – Medium	Variable	Non-catalytic tube	Step 1
7	High mass	1.9 ft^3 – Medium	Variable	Hybrid – catalytic and non-catalytic tube	Step 2
8	Steel	1.7 ft^3 – Medium	Fixed	Non-catalytic tube	Step 1

Table 2. Additional cordwood stoves certified with the ASTM E3053 method.

Stove #	Construction Type	Firebox Size	Emission Controls	EPA 2015 NSPS Certification
9	Steel	2.1 ft^3 – Medium	Non-catalytic tube	Step 2
12	Steel	2.6 ft^3 – Large	Hybrid-catalytic and non-catalytic tube	Step 2
15	Steel	0.8 ft^3 – Small	Non-catalytic tube	Step 2
16	Steel	2.0 ft^3 – Medium	Non-catalytic tube	Step 2
17	Steel/cast iron	3.0 ft^3 – Large	Hybrid- catalytic and non-catalytic tube	Step 2

Table 3. Tests conducted.

Stove #	M28R (Douglas fir crib wood)	ASTM E3053-based test	IDC Development	IDC
1	X	X	X	X
2	X		X	X
4	X		X	X
5	X		X	X
6	X	X	X	X
7	X	X		X
8	X			X
9		X		X
12		X		X
15		X		X
16		X		X
17		X		X

Table 4. Method development assessments.

Element Assessed	Data Evaluated
Ending burn at 90% vs. 100% fuel consumption	M28R and ASTM E3053 runs
Configuration of startup fuel- top-down vs. bottom-up ignition	Research runs in Stoves 1, 2, 4, 5, and 6
Fuel load density	Research runs in Stoves 1, 2, 5, and 6
High-fire phase air setting – high throughout vs. switch to low at 50% fuel load combustion	Research runs in Stoves 1, 2, 5, and 6
Load/setting impact on initial temperature in subsequent phase	M28R and ASTM E3053 runs
Inclusion/exclusion of maintenance phase	Research runs in Stoves 1, 2, 4, 5, and 6
Maintenance phase air setting- medium vs. low	Research runs in Stoves 1 and 5
Start-up phase emissions	IDC runs
Initial position of the stove door	IDC runs in Stove 2
Replicability of results	IDC runs

Table 5. Average times to 90% and 100% fuel consumption by test protocol and stove.

	Time to 90% consumption (minutes)	Time to 100% consumption (minutes)	Time difference (100% – 90% consumption)	Difference as % of total burn time
M28R Runs
Stove 1	158	237	79	32%
Stove 2	128	185	57	31%
Stove 4	62	87	25	28%
Stove 5	175	263	88	31%
Stove 6	144	216	72	34%
Stove 7	168	260	92	33%
ASTM Medium and Low Phases
Stove 1	215	385	171	44%
Stove 6	260	445	185	42%
Stove 7	245	393	148	38%
Stove 16	296	494	198	40%
Stove 17	536	806	271	34%

Table 6. Emission factors and rates at 100% and 90% combustion and percent differences.

	Emission Factor (g/kg)			Emission Rate (g/h)
	100% Comb	90% Comb	% Higher	100% Comb	90% Comb	% Higher
M28R Runs
Stove 1	1.91	2.18	14%	4.32	6.49	52%
Stove 2	0.99	1.11	12%	1.28	1.84	45%
Stove 4	1.75	1.89	9%	2.58	3.50	35%
Stove 5	2.07	2.31	12%	4.30	5.82	48%
Stove 6	1.27	1.41	12%	2.10	3.20	53%
Stove 7	0.36	0.38	5%	0.44	0.62	44%
ASTM Medium and Low Phases
Stove 1	5.29	6.09	14%	10.70	18.84	83%
Stove 6	4.02	4.65	16%	4.72	8.33	76%
Stove 7	0.38	0.43	13%	0.43	0.71	64%
Stove 16	6.34	7.69	24%	6.68	12.56	87%
Stove 17	0.24	0.27	13%	0.22	0.33	54%

Figure 1. Bottom-up versus top-down startup configuration metrics: (a) run time and (b) dry burn rate.

Figure 2. Bottom-up versus top-down startup configuration PM emission metrics: (a) emission factor (g/kg) and (b) emission rate (g/h).

Table 7. Comparison of high-fire phase metrics in runs with different fuel loads.

	Dry Burn Rate (kg/h)		Temp. at End of Phase (^oF)		PM Emission Rate (g/h)		PM Emission Factor (g/kg)
Fuel Density	5 lb/ft^3	7 lb/ft^3	5 lb/ft^3	7 lb/ft^3	5 lb/ft^3	7 lb/ft^3	5 lb/ft^3	7 lb/ft^3
Stove 1	4.66	4.92	521	532	2.72	7.98	0.58	1.62
Stove 2	1.44	1.99	404	420	1.14	7.25	0.79	3.64
Stove 5	3.76	3.86	478	499	30.99	6.52	8.25	1.69
Stove 6	4.46	5.16	545	596	1.28	5.35	0.29	1.04

Figure 3. PM emissions in high-fire phases with and without air setting switched to low.

Figure 4. Stove temperature in high-fire phases with and without air setting switched to low.

Figure 5. Stove temperatures (°F) at the beginning of low and medium burns – Method 28 R and ASTM E3053.

Figure 6. Stove temperatures (°F) at the beginning of low burn phase when that phase was and was not preceded by a maintenance phase.

Figure 7. PM emissions at medium and low air settings: (a) emission factor (g/kg) and (b) emission rate (g/h).

Table 8. Impact of startup phase on total PM emissions and PM ER in stoves with lowest and highest emission rates: mean and [range].

	ER (g/h)	Startup Emissions as % of Total Emissions	% Change in ER if Startup is omitted
Stoves with Lowest ERs (Stoves 7, 12, 15, and 17)	2.5 [1.6–3.5]	28% [25% – 32%]	−21% [−19% – −24%]
Stoves with Highest ERs (Stoves 1, 2, 6, and 16)	14.6 [11.3–21.6]	7% [2% – 11%]	3% [−1% – 7%]

Figure 8. Fuel combustion (a) and stove temperature (b) curves in Stove 2 startup phases by door position in the first five minutes of the test run.

Table 9. Mean and relative standard deviation of emission rates and emission factors in triplicate IDC tests.

Stove Characteristics				PM Emission Rate (g/h)		PM Emission Factor (g/kg)
ID #	Control	Firebox size	Certif. Level	Mean	Rel St. Dev.	Mean	Rel St. Dev.
Stove 1	Non-Catalytic	Large	1	11.8	36%	4.2	34%
Stove 2 −1	Catalytic	Small	2	15.4	81%	11.4	93%
Stove 2–2	Catalytic	Small	2	6.6	77%	4.6	73%
Stove 4	Non-Catalytic	Small	1	6.3	15%	4.5	23%
Stove 5	Non-Catalytic	Medium	1	5.2	80%	2.3	71%
Stove 6	Non-Catalytic	Medium	1	16.1	25%	8.1	20%
Stove 7	Hybrid	Medium	2	1.6	24%	1.1	22%
Stove 8	Non-Catalytic	Medium	1	7.7	22%	2.1	23%
Stove 12	Hybrid	Large	2	3.4	31%	2.0	32%
Stove 15	Non-Catalytic	Small	2	2.9	37%	2.2	36%
Stove 16	Non-Catalytic	Large	2	13.6	17%	7.4	20%
Stove 17	Hybrid	Medium	2	1.9	13%	1.4	14%

Data availability statement

The data that support the findings of the study reported in Development of an Integrated Duty Cycle Test Method to Assess Cordwood Stove Performance are available from the corresponding author, BM, upon reasonable request.