Adiabatic flame calorimeter

In an adiabatic flame calorimeter, the fuel, for example natural gas, or oil, is burnt completely in an atmosphere of oxygen at 1 atmosphere pressure, and the heat is transferred into a known mass of liquid, usually water and the temperature rise AT is measured. Provided heat losses are minimised, the enthalpy change (AH) per mole of fuel is given by the equation ... 

Fig. 1.18 An adiabatic flame calorimeter, an example of an isobaric calorimeter, consists of this component immersed in a stirred water bath. Combustion occurs as a known amount of reactant is passed through to fuel the flame and the rise of temperature is monitored.

The Ohio State University (OSU) calorimeter (12) differs from the Cone calorimeter ia that it is a tme adiabatic instmment which measures heat released dufing burning of polymers by measurement of the temperature of the exhaust gases. This test has been adopted by the Federal Aeronautics Administration (FAA) to test total and peak heat release of materials used ia the iateriors of commercial aircraft. The other principal heat release test ia use is the Factory Mutual flammabiHty apparatus (13,14). Unlike the Cone or OSU calorimeters this test allows the measurement of flame spread as weU as heat release and smoke. A unique feature is that it uses oxygen concentrations higher than ambient to simulate back radiation from the flames of a large-scale fire. 

The experimental data and the calculations involved in the determination of a reaction enthalpy by isoperibol flame combustion calorimetry are in many aspects similar to those described for bomb combustion calorimetry (see section 7.1) It is necessary to obtain the adiabatic temperature rise, A Tad, from a temperaturetime curve such as that in figure 7.2, to determine the energy equivalent of the calorimeter in an separate experiment and to compute the enthalpy of the isothermal calorimetric process, AI/icp, by an analogous scheme to that used in the case of equations 7.17-7.19 and A /ibp. The corrections to the standard state are, however, much less important because the pressure inside the burner vessel is very close to 0.1 MPa. 

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