The fragmentary thermal-conductivity data for argon available in the literature have been correlated by use of a residual thermal conductivity k -k* vs. density p relationship.This correlation produced a unique continuous curve which was found to be singularly independent of temperature and pressure for both gaseous-and liquid-state data. From low-pressure thermal-conductivity values k* and the relationship given above, it is possible to determine thermal conductivities at any condition of temperature and pressure for which a corresponding density is available. This procedure was used to calculate reliable thermal conductivities k for high-pressure regions where experimental data were lacking.In a similar manner the critical thermal conductivity A, for argon was established directly from the critical density and the quantity kT,*. The k, value permitted the calculation of reduced thermal conductivities kR w d made possible the construction of an extensive reduced-state chart. Although this correlation was developed mainly from data for argon, it was found to apply equally as well to the other inert gases as postulated from the theory of corresponding states.A comparison of thermal conductivities calculated from the reduced-state plot with over 200 experimental points produced an average deviation of l.S'% for all the inert gases. This chart was also found applicable to the diatomic gases and their mixtures but produced significant deviations for substances having more than two atoms per molecule.

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In small-scale combustors, the ratio of area to the combustor volume increases and hence heat loss from the combustor’s wall is significantly enhanced and flame quenching occurs. To solve this problem, non-premixed vortex flow is employed to stabilize flames in a meso-scale combustion chamber to generate small-scale power or thrust for propulsion systems. In this experimental investigation, the effects of thermal recuperation on the characteristics of asymmetric non-premixed vortex combustion are studied. The exhaust gases temperature, emissions and the combustor wall temperature are measured to evaluate thermal and emitter efficiencies. The results illustrate that in both combustors (with/without thermal recuperator), by increasing the combustion air mass flowrate, the wall temperature increases while the wall temperature of combustor with thermal recuperator is higher. The emitter efficiency calculated based on the combustor wall temperature is significantly increased by using thermal recuperator. Thermal efficiency of the combustion system increases up to 10% when thermal recuperator is employed especially in moderate Reynolds numbers (combustion air flow rate is 120 mg/s).

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