# Heat Transfer Study on Liner Wall of Heat Recirculating Combustor

- 34 Downloads

## Abstract

In gas turbine combustors, the internal walls of the liner are always subjected to intense radiation heat, always damaging the combustor liner, resulting in cracking and premature failures of the components. For small diameter combustion, as surface-area-to-volume ratio increases, controlling of wall temperatures again becomes more challenging. The present work employs the concept of liquid film evaporation combustor for small-scale combustion chamber. It uses the wall heat loss for evaporation of liquid fuel, which is very effective way of controlling the high wall temperatures. It acts as cushion to the effect of the radiation heating and recirculates the same heat into the chamber as fuel vapor which otherwise leaves the chamber by cooling air. The previous experiments on such combustor show unstable combustion, highly attributed due to evaporation characteristics of fuel. Understanding of wall heat transfer is therefore very important for successful operation of such combustor. The effect of convective heat transfer coefficient and thermal conductivity on the combustor wall temperatures and the amount of heat that is transferred through the combined effect of radiation, convection and conduction at the surface is investigated in present work. The study is carried out considering both the cases, i.e., without liquid film and with liquid film on outer surface of combustor wall. A computer program in MATLAB using important parameters as input is used to handle the heat transfer computations. The study reveals that the thermal conductivity affects the outer wall temperature, whereas the convective heat transfer coefficient affects both outer and inner wall temperatures. Combustor with liquid film handles higher values of heat flux with relatively lower wall temperatures as compared with the combustor without liquid film.

## Keywords

Wall heat transfer Heat recirculation Convective heat transfer Combustion chamber## List of Symbols

*L*Length of cylinder

*D*Diameter of cylinder

- \(\varGamma_{\text{L}}\)
Initial mass flow per unit width

- \(\varGamma_{0}\)
Outlet mass flow per unit width

- \(k_{\text{l}}\)
Thermal conductivity

- \(h_{\text{lv}}\)
Latent heat of vaporization

- \(\rho_{\text{l}}\)
Density of liquid

- \(\rho_{\text{v}}\)
Density of vapor

- \(\mu_{\text{l}}\)
Viscosity

- \(\bar{h}\)
Average heat transfer coefficient

- \(Re\)
Reynolds number

- \(\dot{m}_{\text{evp}}\)
Rate of evaporation

- \(\dot{m}_{\text{f}}\)
Mass flow rate of fuel

- \(\delta_{\text{L}}\)
Film thickness

*T*_{wan}Initial guess value of outer wall temperature

- \(T_{\text{s}}\)
Saturation temperature

*T*_{wo}Outer wall temperature

*T*_{g}Gas temperature

- \(T_{\text{w}}\)
Wall temperature

*T*_{surr}Surrounding temperature

*T*_{wi}Inner wall temperature

*T*_{wig}Inner wall temperature based on gas temperature

*r*_{i}Radius to inner wall surface from center of cylinder

*r*_{o}Radius to outer wall surface

*A*_{i}Convective and radiative heat transfer external surface area

*A*_{o}Convective and radiative heat transfer internal surface area

*R*_{rado}Radiative heat resistances for outer wall

*R*_{radi}Radiative heat resistances for inner wall

*R*_{convo}Convective thermal resistances for outer wall

*R*_{convi}Convective thermal resistances for inner wall

*R*_{th}Conductive thermal resistances in material

*R*_{total}Total thermal resistance of the system

*h*_{o}Convective heat transfer coefficient for external wall surface

*h*_{i}Convective heat transfer coefficient for internal wall surface

- \(k_{\text{w}}\)
Wall thermal conductivity

- em
Emissivity

- ap
Stefan–Boltzmann constant

## Notes

### Compliance with Ethical Standards

### Conflict of interest

The authors declare that they have no conflict of interest.

## References

- 1.W.A. Sirignano, T.K. Pham, D. Dunn-Rankin, Miniature-scale liquid-fuel-film combustor. Proc. Combust. Inst.
**29**, 925–931 (2002)CrossRefGoogle Scholar - 2.L.S.V. Prasad, K. Rajesh Chandra, Thermo structural analysis on a marine gas turbine flame tube. Int. J. Eng. Bus. Enterp. Appl.
**7**(1), 83–88 (2014)Google Scholar - 3.C.-H. Tsai, S.-S. Hou, T.-H. Lin, in
*A theoretical study on excess enthalpy flames in a one-dimension duct of varying cross sectional area*. 16th International Symposium on Transport Phenomena, ISTP-16,2005, PragueGoogle Scholar - 4.A.H. Lefevebre,
*Gas turbine combustion*, 2nd edn. (Taylor & Francis, Abingdon, 1998)Google Scholar - 5.G.E. Andrews, D. Bradley, Determination of burning velocities: a critical review. Combust. Flame
**18**, 133–153 (1972)CrossRefGoogle Scholar - 6.A. Faghri, Y. Zhang,
*Transport phenomena in multiphase systems*(Elsevier Academic Press, Amsterdam, 2006)Google Scholar - 7.E. Ufot, B.T. Lebele-Alawa, Influence of convection heat transfer coefficient on heat transfers and wall temperatures of gas-turbine combustors. Int. J. Appl. Sci. Technol.
**1**(6), 210–218 (2011)Google Scholar - 8.M. da Graga Carvalho, P.J. Coelho, Heat transfer in gas turbine combustors. J. Themophys. Heat Transfer.
**3**(2), 123–131 (1989)CrossRefGoogle Scholar - 9.G. Manoj Kumar, J. Bruce Ralphin Rose, Numerical comparative study on convective heat transfer coefficient in a combustor liner of gas turbine with coating. Int. J. Mech. Eng. Res.
**5**(1), 0973–4562 (2015)Google Scholar - 10.N. Yun, Y.H. Jeon, K.M.Kim, in
*Thermal and creep analysis in a gas turbine combustion*. Proceedings of the 4th IASME/WSEAS International Conference on ENERGY & ENVIRONMENT (EE)Google Scholar - 11.S. Matarazzo, H. Laget, in
*Modelling of the heat transfer in a gas turbine liner combustor*. Chia Laguna, Cagliari, September 11–15 (2011)Google Scholar