Experimental Study of an Integral Catalytic Combustor-Heat Exchanger for Stirling Engines 820418
An experimental study was conducted to determine the feasibility of using catalytic combustion with heat removal for the Stirling engine to reduce exhaust emissions and also improve heat transfer to the working fluid. The study was conducted using spaced parallel plates. An internally air-cooled heat exchanger was placed between two noble metal catalytic plates. A preheated fuel-air mixture passed between the plates and reacted on the surface of the catalyzed plates. Heat was removed from the catalytic surface by radiation and convection to the air-cooled heat exchangers to control temperature and minimize thermal NOx emissions. The study was conducted at inlet combustion air temperatures from 850 to 900 K, inlet velocities of about 10 m/s, equivalence ratios from 0.5 to 0.9, and pressures from 1.3×105 to 2.0×105 Pa. Propane fuel was used for all testing. Combustion efficiencies greater than 99.5 percent were measured. NOx emissions ranged from 1.7 to 3.3 g NO2/kg fuel. The results demonstrate the feasibility of the concept and indicate that further investigation of the concept is warranted.