Interpretation of thermocouple readings in a flame must be made with the assistance Site URL List 1|]# of an appropriate energy balance Inhibitors,Modulators,Libraries model because there are various heat exchange mechanisms at play, depending on type and size of flame, and local events, including flow fluctuations and variable radiant path lengths between the probe and surroundings both inside and outside the flame. With an appropriate heat balance model for a particular flame, the thermocouple readings may be corrected for net energy transfer including radiation with Inhibitors,Modulators,Libraries the environment that the thermocouple ��sees,�� and convection heat transfer from hot combustion gases. Such corrections have been addressed by various researchers in flame temperature measurements [2-3].
More specifically, in Inhibitors,Modulators,Libraries clean premixed laboratory burner scale flames, the indicated Inhibitors,Modulators,Libraries temperature measurement may be as much as 800 ��C or more below the combustion gas temperature (calculated from adiabatic equilibrium and confirmed experimentally by CARS [4]). This is due to the thermocouple energy balance that includes input from combustion gas convection and surface heat loss to the surroundings outside the flame by radiation from the thermocouple; this factor becoming very large when the thermocouple surface reaches temperatures of 1,200-1,500 K. In clean laboratory flames, the participation by gas band emission or absorption from carbon dioxide and water vapor are negligible and soot is not present in abundance.
In small laboratory diffusion flames where soot is present, there will be a component of radiation which depends on both the soot volume fraction and on radiation path lengths.
Inhibitors,Modulators,Libraries Inhibitors,Modulators,Libraries In very large flames, such as pool fires, the soot volume fraction can be large, and the path length through the flame to the surroundings can be large so that the thermocouple Inhibitors,Modulators,Libraries is not in communication with surfaces outside the flame. Hence, utilization of thermocouples in flames requires a rather sophisticated method for performing an appropriate energy balance which accounts for the different environments that the thermocouple ��sees.�� It is typical to use a Inhibitors,Modulators,Libraries computer program or fire code for this purpose.
In this manner, the flow field, the local convection coefficient to the thermocouple, an estimate of the soot volume fraction, Drug_discovery Batimastat the path length for radiation, all can be taken into account so that the thermocouple reading can be interpreted.
A presentation of such sellekchem an effort is discussed extensively in [4]. Although there is still some unresolved uncertainty, this study found that such a fire code can account for more than 90% selleckchem of the 800 ��C discrepancy noted above.Fire codes predict average values in a particular region of the flame so do not consider the influence of local fluctuations in temperature of both combustion gases, and soot radiation in the vicinity of a thermocouple.