Real Operating Parameters of Bioethanol Burners in Terms of Heat Output.

The aim of this study was to determine the operating parameters of bioethanol burners used in the so-called bioethanol fireplaces, mainly in terms of their actual heat output. The method used to determine the actual heat output was designed considering procedures from the standard EN 16647 fireplaces for liquid fuel. Experiments were carried out on eight different types of burners with two different types of fuels. The measurements demonstrated a difference of up to 19% in the maximal heat output among individual fuels and a difference of up to 16% in the average heat output when comparing identical burners over approximately 60 min of operation. The average heat outputs of the burners during the measurements reached approximately 41-62% of the heat output declared by the manufacturers. The measured values were used to create graphs of the dependency of the burner opening size on its average heat output based on the fuel type. Two-chambered burners reached a higher average heat output than single-chambered burners with the same burner opening area of above ∼6000 mm2. The positions of the regulation damper (75 and 50%) increased the burning time by 21 and 86%, respectively.

PAH emissions from old and new types of domestic hot water boilers.

Five different domestic heating boilers (automatic, over-fire, with down-draft combustion and gasification) and three types of fuel (lignite, wood and mixed fuel) were examined in 25 combustion tests and correlated with the emissions of particulate matter (PM), carbon monoxide (CO), total organic carbon (TOC) and 12 polycyclic aromatic hydrocarbons (PAHs with MW = 178-278 g/mol) focusing on particle phase. However, the distribution of 12 PAHs in gas phase was considered as well due to the presence mainly of lighter PAHs in gas phase. The PAHs, as well as the CO and TOC, are the indicators of incomplete combustion, and in this study PAH emission increased significantly with increasing emissions of CO and TOC. The PAHs were mainly detected on PM2.5, their contents were increasing linearly with increasing PM2.5 emissions. The highest emission factors of PAHs were measured for boilers of old construction, such as over-fire boiler (5.8-929 mg/kg) and boiler with down-draft combustion (3.1-54.1 mg/kg). Modern types of boilers produced much lower emissions of PAHs, in particular, automatic boiler (0.3-3.3 mg/kg) and gasification boilers (0.2-6.7 mg/kg). In general, the inefficient combustion at reduced output of boilers generated 1.4-17.7 times more emissions of PAHs than the combustion at nominal output of boilers. It is recommended to operate boilers at nominal output with sufficient air supply and to use the proper fuel to minimise PAHs emissions from domestic heating appliances.