Experimental investigation of premixed combustion and thermal efficiency in a porous heating burner

Abstract

Summary In the present research, thermal efficiency and the amount of pollutant emissions of a metallic porous burner with a heat exchanger were investigated experimentally. A very important issue about these burners is the stability of flame on the surface of the porous medium. In the present research, through creating a surface flame in the porous medium, the performance of the burner was observed. In this article, by changing the factors like thermal power and equivalence ratio, thermal efficiency and the amount of pollutants were studied. Results showed that the best performance of the burner occurred when the equivalence ratio was 0.8. The maximum thermal efficiency of 39.43% occurred at an equivalence ratio of 0.8 and thermal power of 100 kW. As thermal power increased, the amount of emitted nitric oxide (NOx) increased. Approximately at all measured conditions, the amount of emitted NOx was less than 15 ppm. Also, the amount of emission carbon monoxide (CO) at an equivalence ratio of 0.8 and thermal power of 100 kW was the lowest. In this research, results of the porous burner were compared to the free flame burner and the results revealed that in the best condition, thermal efficiency was improved up to 5.8%. Accordingly, the amount of emitted NOx was reduced strongly but the amount of CO of the porous burner was much more than the open flame burner.

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“…Generally, the roaster consists of six main parts: the roasting drum, the outer frame of the drum with the coffee inlet and outlet hoppers, the main motor driver, the heater, the cooler, and the temperature controller [6]. Several parameters should be considered to obtain the best roaster design, such as the drum dimensions and material [7], temperature, roasting time, efficiency in induction heating roasters [8], the number of holes, and burner diameter [9]. Some commercial coffee roasters using electric heaters for the home industry are widely used [10].…”

“…Where 𝐷 𝑝 = Inner diameter of pulley (mm), 𝑑 𝑚𝑖𝑛 𝑖𝑠 Minimum diameter (mm), 𝑖 is rotational speed ratio and 𝑑 𝑘 𝑖𝑠 𝑑 𝑝 + 2 × 5.5. Secondly 𝐷 𝑘 is Outer diameter of pulley 1 (mm), 𝑑 𝑘 is outer diameter of pulley 2 (mm), 𝐷 𝑝 is Diameter of pulley (mm) and 𝑑 𝑝 𝑖𝑠 Minimum Diameter (mm) 𝐷 𝑝 = 𝑑 𝑚𝑖𝑛 × 𝑖(9)…”