Flame Temperatures in Wood Burning Fires: Hardwood vs. Softwood

Friday, February 12, 2016
Faith C. Myers, Big Walnut High School, Sunbury, OH
The purpose of this experiment was to determine if hardwood (oak) or softwood (poplar and pine) produce more thermal energy by measuring maximum flame temperatures and burn times, and determining relative areas under temperature-time curves. Research and Myers’ previous experimentation led to the hypothesis: hardwood will produce the highest amount of thermal energy based on flame temperatures. The hypothesis was tested by evaluating maximum flame temperatures generated. Eight pieces of wood (each 0.6 cm long and 3.2 cm in diameter) were dipped into kerosene and placed onto shredded paper (25g) in a fireplace. Kerosene (5 ml) was poured onto the wood and the paper was ignited with a match. After burn-off of kerosene and paper (1 minute), maximum flame temperatures (°C) were recorded at 1s intervals until flame-out for each wood type using an infrared (IR) thermometer - and the maximum temperature for each trial recorded.  Ten trials were performed for each wood type and maximum temperatures were averaged and standard deviations calculated.  The mean maximum flame temperatures were:  pine 504.8°C, poplar 501.2°C, and oak 499.5°C.  This result did not support the hypothesis, as the difference in maximum flame temperatures was statistically insignificant.  The mean burn time (minutes) was: oak 12.2, pine 7.4, and poplar 7.2, supporting the hypothesis.  The mean relative area under the temperature-time curve was:  oak 258, pine 182, and poplar 175, supporting the hypothesis.  Therefore, the hypothesis that hardwood would produce more thermal energy than softwoods was supported by two of three thermal energy indicators.