The Effects of Load Height on the Emissions from a Natural Gas-Fired Domestic Cooktop Burner

Abstract

A single production cooktop burner was studied at three levels of thermal input, to determine the effects of load height on its efficiency and gaseous emissions. In this work, load height was defined as the vertical distance from the center of the base of the load vessel to the top of the burner ports. To simulate practical operation as closely as possible, the production gas injector was used, so that primary aeration varied with thermal input in these experiments. The Australian Gas Association regulations limit the operating range of load height for this burner to values between 7mm (CO/CO₂ <0.01) and 48 mm (efficiency > 40%). Minimum NO₂ emission rates of 8.7,8.0 and 8.8 ng/J were observed at load heights of 25, 40 and 48 mm respectively, at thermal inputs of 0.49, 0.83 and 1.65 kW respectively.

A new measure of pollutant emission was proposed, to provide a means of assessing the “balance” between the requirements for lower emission rate and higher thermal efficiency. The total emission of a pollutant was calculated for the duration of a standard cooking task, using simultaneously-measured thermal efficiency and emission rate data. ForNO₂, this total emission was minimised at load heights of 20, 30 and 18 mm for thermal inputs of 0.49,0.82 and 1.65 kW respectively. Therefore, the standard operating load height (18 mm) for this burner already minimises this total NO₂ emission at its designed maximum thermal input.

Key Words:

• Emisiont
• cooktop
• burners
• gas
• load height