Compact design of planar stepped micro combustor for portable thermoelectric power generation

• Published in: Energy conversion and management Vol. 156; pp. 224 - 234
• Main Authors: Aravind, B., Raghuram, Gannena K.S., Kishore, V. Ratna, Kumar, Sudarshan
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 15.01.2018; Elsevier Science Ltd
• Subjects: Aluminum; Backward facing steps; Combustion chambers; Conversion; Conversion efficiency; Design; Electric power generation; Electricity generation; Energy efficiency; Equivalence ratio; Flame stability; Flow rates; Flow velocity; Liquefied petroleum gas; Load resistance; Micro combustors; Military applications; Natural gas; Porous media; Studies; Temperature distribution; Thermoelectric generator; Thermoelectric generators; Thermoelectric power generation; Thermoelectricity; Conversion efficiency; Thermoelectric generator; Flame stability; Micro combustors
• ISSN: 0196-8904; 1879-2227
• DOI: 10.1016/j.enconman.2017.11.021

•Developed a novel micro combustor for portable thermoelectric power generation.•The proposed system size is compatible with a conventional electrochemical battery.•The proposed system offers high power density with high conversion efficiency.•Thermal and power characteristics of the system are investigated in detail. An efficient prototype of a micro power generator with integrated micro combustor has been developed in the present study. The proposed design of the integrated micro-combustor provides high surface temperature with superior temperature uniformity and enhanced flame stability limits, a prerequisite for a thermoelectric power generation system. This novel micro combustor configuration consists of three backward facing steps with a recirculation hole fabricated in a rectangular heating medium of aluminium material. Parametric studies are carried out by varying the mixture inlet velocity, equivalence ratio and coolant flow rate to obtain the optimized operating conditions for maximum power generation. Two thermoelectric modules are mounted on the system operating with liquefied petroleum gas as fuel. A maximum conversion efficiency of 3.3% is obtained at ϕ = 0.95 with a mixture velocity of 7.5 m/s and a load resistance of 4 Ω across the thermoelectric generator. The effect of porous media is investigated to enhance the flame stability limits in the micro combustor. Porous media significantly enhances the upper flame stability limits and maximum conversion efficiencies (3.8%, 4.03%, and 3.73% at ϕ = 1, 0.9 and 0.8 at 10 m/s). A significantly higher power density (∼50% higher than existing systems) of 0.12 mW/mm3 of system volume is achieved. A compact design of the prototype system with high conversion efficiency shows the possibility of its application for various systems requiring portable power for remote, stand-alone, military and aerospace applications.