How can I use a candle to heat glass/quartz to a specific temp Excuse my ignorance of physics. Is it possible to suspend glass or quartz over a candle at a specific distance (in. or mm.) in order to heat the object to a certain temperature, say 300 C. Is there a graph anywhere for something like this? The convection heat transfer above a candle flame? I'm trying to find the temperatures ABOVE a flame but can only find the temperature OF a flame.
Or say I put a funnel upside down over a candle, leaving room for oxygen at the bottom, will that force the heat up out of the top of the funnel and create more temperature control in regards to my first question?
Any help would be appreciated, thanks!
 A: You can estimate the plume temperature above a fire using correlations from Heskestad or McCaffrey, listed respectively below:
$$T_0=25(\dot Q ^{2/5}_c/(z-z_0))^{5/3} + T_ \infty$$
$$T_0=22.3(\dot Q ^{2/5}_c/z)^{5/3} + T_ \infty$$
Where $T_0$ is the centreline plume temperature, $\dot Q_c$ is the convective heat release rate of the fire, $z$ is the height above the fire source, $z_0$ is the virtual origin and $T_ \infty$ is ambient temperature (all temperatures in Celsius). Virtual origin can be estimated (Heskestad) by:
$$z_0/D=-1.02+0.083 \dot Q^{2/5}_c/D$$
Within the flame region, one typically assumes a constant temperature (the flame temperature of say 800 °C). This was all derived from work with heptane, methane burners.
Some issues you may encounter:


*

*This is for undisturbed plumes, which is impractical in "the real world".

*You can't put an item in a plume at 300°C and expect it to heat to 300°C - there is one more major factors at play: heat gains and losses to the quartz plate both by convection and radiation. You will need to determine your energy gains and losses to predict your plate temperature.


Another interesting piece of work which may help you has been carried out by NIST (http://fire.nist.gov/bfrlpubs/fire05/PDF/f05141.pdf) which characterises heat fluxes at various locations above a candle flame.
