Sub-micron particle number emission from residential heating systems: A comparison between conventional and condensing boilers fueled by natural gas and liquid petroleum gas, and pellet stoves

Elisa Caracci; Laura Canale; Giorgio Buonanno; Luca Stabile

doi:10.1016/j.scitotenv.2022.154288

Sub-micron particle number emission from residential heating systems: A comparison between conventional and condensing boilers fueled by natural gas and liquid petroleum gas, and pellet stoves

Sci Total Environ. 2022 Jun 25:827:154288. doi: 10.1016/j.scitotenv.2022.154288. Epub 2022 Mar 3.

Authors

Elisa Caracci¹, Laura Canale², Giorgio Buonanno³, Luca Stabile⁴

Affiliations

¹ Department of Civil and Mechanical Engineering, University of Cassino and Southern Lazio, Cassino, FR, Italy.
² Department of Civil and Mechanical Engineering, University of Cassino and Southern Lazio, Cassino, FR, Italy; Department of Economics, Universitas Mercatorum, Piazza Mattei 10, Rome, Italy.
³ Department of Civil and Mechanical Engineering, University of Cassino and Southern Lazio, Cassino, FR, Italy; International Laboratory for Air Quality and Health, Queensland University of Technology, Brisbane, Australia.
⁴ Department of Civil and Mechanical Engineering, University of Cassino and Southern Lazio, Cassino, FR, Italy. Electronic address: l.stabile@unicas.it.

PMID: 35248635
DOI: 10.1016/j.scitotenv.2022.154288

Abstract

Pollutant emissions from residential heating systems represent a main concern in terms of outdoor air quality. Differently from other pollutants, sub-micron particle emission from heating systems has not yet been exhaustively characterized by the scientific literature, with limited data available, in particular, for gas-fueled boilers. In the present paper, an experimental campaign to measure the sub-micron particle number concentrations and distributions at the stack of different automatically-fed small-scale heating systems (conventional and condensing boilers fueled by natural gas and liquid petroleum gas, and pellet stoves) was performed. Based on the measured concentrations, corresponding emission rates and emission factors were also estimated. The results of the experimental campaign revealed that the highest concentrations were measured for pellet stoves (median value >10⁷ part. m^-3), whereas conventional (about 1 × 10⁶ part. m^-3) and condensing boilers (<10⁶ part. m^-3) presented much lower concentrations. No effect of the fuel (natural gas, liquid petroleum gas) on the total concentration measured at the stack of boilers was recognized, whereas a smaller distribution mode (at 10 nm) was measured for gas-fired boilers. Because of the particle concentration values, the highest particle emission rates and factors were the pellet stove ones (median values of 2.1 × 10¹⁵ part. h^-1 and 8.4 × 10¹³ part. kWh^-1, respectively), whereas emission rates for conventional and condensing boilers were about 5 × 10¹³ part. h^-1 and 2 × 10¹³ part. h^-1, respectively. The estimated emission factors were also adopted to perform a simplified evaluation of the relative contributions of the investigated automatically-fed small-scale heating systems in terms of particle number on a national scale (Italy): we obtained that the pellet stove contribution is the main one as it accounts for 87% of total emissions of particle number for heating purpose.

Keywords: Boilers; Emission factor; Emission rate; Particle number; Pellet stoves; SMPS.

MeSH terms

Air Pollutants* / analysis
Air Pollution* / analysis
Environmental Pollutants*
Heating
Natural Gas
Particulate Matter / analysis
Petroleum*

Substances

Air Pollutants
Environmental Pollutants
Natural Gas
Particulate Matter
Petroleum