Research PaperNumerical investigations on thermal performance of a micro-cylindrical combustor with gradually reduced wall thickness

- A micro-cylindrical combustor with gradually reduced wall thickness is developed.
- The enhancing heat transfer mechanism of the developed combustor is revealed.
- Outer wall temperature of two different micro combustors are compared.
- Effects of inlet/outlet diameter ratio on outer wall temperature are investigated.
- Solid material with lower thermal conductivity is good for the developed combustor.

Micro combustor is the key component of the micro-thermophotovoltaic (MTPV) system. A high and uniform wall temperature distribution on the micro combustor is helpful for obtaining higher energy conversion efficiency. In this work, a micro-cylindrical combustor with gradually reduced wall thickness is developed. The micro-cylindrical combustors with gradually reduced wall thickness are widely investigated and compared with the micro-cylindrical combustors with a step under various conditions. Results suggest that the micro-cylindrical combustors with gradually reduced wall thickness has a higher and more uniform wall temperature distribution under various H2/air equivalence ratios, H2 mass flow rates and inlet/outlet diameter ratios compared with that of the micro-cylindrical combustors with a step. However, it should be noted that effects of solid material on the outer wall temperature of the two micro-cylindrical combustors are interesting. The thermal performance of micro-cylindrical combustor with gradually reduced wall thickness is better under the solid material of quartz whose thermal conductivity is low, while the positive effects brought by the micro-cylindrical combustor with gradually reduced wall thickness disappear under the solid material of silicon carbide whose thermal conductivity is high.

A micro-cylindrical combustor with gradually reduced wall thickness for micro-thermophotovoltaic system.165