The biomass fueled micro-scale CHP unit with stirling engine and two-stage vortex combustion chamber

• Published in: Heat and mass transfer Vol. 58; no. 7; pp. 1091 - 1103
• Main Authors: Borisov, Igor, Khalatov, Artem, Paschenko, Denis
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 2022; Springer Nature B.V
• Subjects: Air supplies; Biomass burning; Combustion chambers; Dimpling; Downdraft; Efficiency; Electric generators; Engineering; Engineering Thermodynamics; Gas temperature; Gasification; Heat and Mass Transfer; Heat exchangers; Industrial Chemistry/Chemical Engineering; Low pressure; Original Article; Permanent magnets; Regenerators; Stirling engines; Suction; Thermal analysis; Thermodynamic efficiency; Thermodynamics; Vortices; Working fluids
• ISSN: 0947-7411; 1432-1181
• DOI: 10.1007/s00231-021-03165-z

The improved biomass (wood pellet) fuelled micro-CHP design is considered, based on 0.5 kWe Stirling engine, two-stage vortex combustion chamber, enhanced recuperator and waste heat utilizing heat exchanger are designed and tested. The vortex ejector was used between the primary (downdraft gasifier) and secondary combustion chambers. The secondary air supplies tangentially to create the low pressure in the ejector axial zone for the wood gas suction from the primary chamber to secondary ceramic chamber. The product gas is mixed with secondary air and creates the combustible gas-air mixture. The γ-type Stirling engine with nitrogen as a working fluid and built-in electric generator with permanent magnets is used in CHP unit. The recuperator with heat transfer augmentation by surface dimples and protrusions with thermal efficiency of 0.68 was developed. The averaged gas temperature at the hot side of heat exchanger was 1150 °C, while the heat exchanger external surface temperature was 810 °C, which ensured the stable SE operation. The SE efficiency achieved in experiments is 14.8%, the overall CHP efficiency is 65%. A theoretical model which is able to simulate the main thermodynamic parameters of CHP unit was developed; the thermal analysis of CHP unit was made.