Characterization of in-stack particulate emissions from residential wood hydronic heater appliances under different combustion conditions

Figures & data

Figure 1. Schematic of combustion test setup featuring locations of instrumentation, instrument flow requirements, and instrument groupings.

Table 1. Comparison of the US EPA certification and design parameters for the wood chip/pellet and cordwood hydronic heaters featured in this study.

Parameter	Appliance 1	Appliance 2	Appliance 3
Emission Rate	0.02 lb/mmBTU	0.07 lb/mmBTU	0.07 lb/mmBTU
Maximum Rated Output	120,000 BTU (35 kW)	102,408 BTU (30 kW)	125,000 BTU (36.6 kW)
Overall Efficiency	85%	67%	68%
Water Jacket Volume	15 gallon (56.7 Lr)	55 gallon (227.3 L)	100 gallon (378.5 L)
Fuel Type	Chips/Pellet	Cordwood	Cordwood
Catalyst	No	Yes	No
NSPS 2015 Compliant	Yes	Yes	Yes
NSPS 2020 Compliant	No	Yes	No

Table 2. Summary of operating condition mean PNC (units of: C (concentration #/cm³)/dlog (particle size (d_p)), PMC (units: milligram per cubic meter), and PSAC (units: square micrometers per cubic centimeter) results.

		PNC, C/dlogdp		PMC, mg/m^3		PSAC, µm^2/cm^3
Appliance #	Condition	ELPI	SMPS	ELPI	pDR	ELPI	NSAM
1	Startup	3.45E+07	2.54E+08	190	6	1.46E+06	8.59E+04
	Low	3.08E+07	2.45E+08	154	2	1.21E+06	7.26E+04
	High	3.09E+07	1.81E+08	575	2	1.67E+06	8.21E+04
	Burnout	2.16E+07	1.05E+08	108	25	1.03E+06	4.97E+04
2	Startup	5.15E+07	1.44E+08	358	732	3.56E+06	-
	Low	4.64E+06	1.14E+07	9	10	1.45E+05	-
	High	2.32E+07	8.89E+07	49	25	7.07E+05	-
	Burnout	2.51E+07	9.79E+07	24	2	4.23E+05	-
3	Startup	1.89E+07	6.80E+07	88	87	9.80E+05	8.33E+04
	Low	8.03E+06	6.75E+07	18	3	2.34E+05	4.70E+04
	High	1.75E+07	9.40E+07	50	6	6.21E+05	6.13E+04
	Burnout	4.11E+06	2.79E+07	9	3	1.16E+05	2.36E+04

Table 3. Summary of PSD results from ELPI and SMPS for all three appliances across each of four operating conditions.

		ELPI			SMPS
Appliance #	Condition	N, dC/dlogdp	dg, µm	σg	N, dC/dlogdp	dg, µm	σg
1	Startup	3.35E+07	0.200	1.73	2.54E+08	0.109	1.44
	Low	3.00E+07	0.190	1.78	2.45E+08	0.102	1.43
	High	2.03E+07	0.224	1.65	1.81E+08	0.112	1.45
	Burnout	2.10E+07	0.158	1.94	1.05E+08	0.128	1.56
2	Startup	5.15E+07	0.256	1.69	1.42E+08	0.190	1.66
	Low	4.64E+06	0.180	1.91	1.11E+07	0.178	1.78
	High	2.32E+07	0.178	1.77	8.85E+07	0.125	1.66
	Burnout	2.51E+07	0.186	1.82	8.92E+07	0.094	1.59
3	Startup	1.77E+07	0.155	2.51	6.80E+07	0.178	1.60
	Low	7.81E+06	0.086	2.34	6.75E+07	0.097	1.64
	High	1.69E+07	0.148	2.19	9.40E+07	0.139	1.57
	Burnout	4.00E+06	0.080	2.98	2.79E+07	0.158	1.61

Figure 2. Scatterplot comparisons of data collected during testing of Appliance 1 over four different operating conditions: startup, low-output, high-output, and burnout. (A) PNC comparison between ELPI and SMPS. (B) Comparison of d_g as calculated from ELPI and SMPS data. (C) Comparison of PMC_2.5 between the ELPI and pDR. (D) Comparison of PSAC results, specifically comparing the ELPI PSAC estimate versus the NSAM LDSA.

Figure 3. Timeseries plots of PNC measured during testing of chip boiler during two duplicate experiments with the four operating conditions using the ELPI. Red solid lines illustrate the first test run and the black dashed lines illustrate the second test run.

Figure 4. Scatterplot comparisons of data collected during testing of Appliance 2 over four different operating conditions: startup, low-output, high-output, and burnout. (A) PNC comparison between ELPI and SMPS. (B) Comparison of d_g as calculated from ELPI and SMPS data. (C) Comparison of PMC_2.5 between the ELPI and pDR. (D) Comparison of PSAC results, could not be performed due to a malfunction of the NSAM during this experiment.

Figure 5. Scatterplot comparisons of data collected during testing of Appliance 3 over four different operating conditions: startup, low-output, high-output, and burnout. (A) PNC comparison between ELPI and SMPS. (B) Comparison of d_g as calculated from ELPI and SMPS data. (C) Comparison of PMC_2.5 between the ELPI and pDR. (D) Comparison of PSAC results, specifically comparing the ELPI PSAC estimate versus the NSAM LDSA.