Study of the infrared gas heaters characteristics under forced surface combustion modes

Experimental studies of the combustion process of natural gas and air mixtures have been carried out on laboratory models of a gas infrared heater (GIH) operating in forced surface combustion (FSC) modes. The combustion process took place near the surface of the plates made of heat-resistant metal alloy (Ni 25%, Al 6%, Fe base). The design of the GIH models and the FSC mode allowed the authors to implement the stable surface combustion modes in the range of values of the firing rate from 2.15 to 7.55 MW/m² per unit cross-sectional area of the gas flow. The experiments were carried out on two models. Dimensions of the system of radiating plates of the first model are: width 78 mm; length 92 mm; and height from 110 to 250 mm. Dimensions of the radiating surface of the second model are: width 78 mm; length 92 mm; and height 403 mm. Combustion power in the models of the GIH varied in the range from 12 to 42.2 kW. The concentration of nitrogen oxides in the combustion products was less than 16 ppm and the concentration of carbon monoxide was less than 10 ppm at the values of the air-to-fuel equivalence ratio 1.5. The maximum temperature of the outer surface of the radiating plates was 1280 ^◦C. The coefficient of conversion of combustion energy into radiation energy for the model of the GIH with a height of 403 mm reached the values exceeding 40%.