Development of a premixed burner integrated thermoelectric power generator for insect control

Electrical power generation using hydrocarbons presents a huge potential owing to their higher power densities and environmental factors associated with lithium ion batteries. Small scale combustors have been widely developed and tested for power generation purpose employing Thermoelectrics and Thermophotovoltaic conversion of combustion heat into electricity. This thesis is concerned with development and investigation of a novel non-catalytic meso scale self-aspirating premixed burner integrated thermoelectric generator for a CO2 Generator device having its application in the insect control industry. Flame stabilisation has been one of the main issues in small scale combustion systems due to higher surface to volume ratio associated with small size of the combustor. Previous research has shown that catalytic combustion is one way of improving flame stabilisation, however employing a catalyst into the system increases the manufacturing cost which can be a significant downside. This research work studies flame stabilisation mechanisms in meso-scale burner which mainly focuses on Backward Facing Step or Sudden Expansion Step and secondary air addition into the combustion chamber. A 250 W premixed burner was developed which was classified as a meso scale burner whose operating parameters were in a range of micro-combustors whereas the size was comparatively bigger due to its integration with standard size thermoelectric modules. The first phase of the research was concerned with development of the burner which included optimisation of the design to achieve a stable enclosed premixed flame as per the design and operational requirements. It was found that flame blowoff can be prevented by addition of secondary air into the combustion chamber downstream of the step. The second phase of the research focused on the integration of the burner with thermoelectric power generators. This involved investigation of various configurations to optimise the electrical power output. The burner integrated thermoelectric unit was then tested in the actual field to validate the concept of integrating combustion and thermoelectrics for small scale power generation applications. The final phase of the research involved a study on the effect of secondary air addition on flame stabilisation in burners employing backward facing step. The minimum secondary air requirement for burner with different step heights was determined. The addition of secondary air cross-stream into the combustion chamber creates stable recirculation zone which reduces the local stream velocity and hence prevents flame blowoff