Research Article | Open Access
Wide-Beam X-Ray Source Target Thermal Management Simulation Using Inner Jet Cooling
A wide-beam area X-ray source has been proposed as a practical replacement for synchrotron sources in clinical DEI applications. Due to a wide X-ray illumination area, a decrease in X-ray flux is expected and thus high electron beam currents up to 3A are considered. To ensure the target performance without deterioration, melting, cracking, or even evaporation, an active cooling system is required for the target block in order to remove the heat and allow for sufficient scanning time. In this study, jet cooling of the target back is investigated for a prototype proof-of-principle target. The prototype target was simulated with the transient k- turbulence multiphysics model in ANSYS CFX. The simulations were conducted at a heat flux of W/, consistent with values anticipated for a full scale target. The simulation results show that the target temperature exceeds the copper melting point in 2 seconds at inlet velocities below 2 m/s. Also, critical heat flux calculations show that a 1.5 m/s inlet velocity at atmospheric pressure is a lower limit for prevention of target burnout using water as a coolant. Inlet velocities in excess of 2 m/s allows for steady-state operation while satisfying all thermal design constraints.
- C. H. Kim, M. A. Bourham, and J. M. Doster, “A wide-beam X-ray source suitable for diffraction enhanced imaging applications,” Nuclear Instruments and Methods in Physics Research Section A, vol. 566, no. 2, pp. 713–721, 2006.
- D. Chapman, W. Thomlinson, R. E. Johnston et al., “Diffraction enhanced X-ray imaging,” Physics in Medicine and Biology, vol. 42, no. 11, pp. 2015–2025, 1997.
- Z. Zhong, W. Thomlinson, D. Chapman, and D. Sayers, “Implementation of diffraction-enhanced imaging experiments: at the NSLS and APS,” Nuclear Instruments and Methods in Physics Research Section A, vol. 450, no. 2-3, pp. 556–567, 2000.
- J. T. Bushberg, J. A. Seibert, E. M. Leidholdt, Jr., and J. M. Boone, The Essential Physics of Medical Imaging, Lippincott Williams & Wilkins, Baltimore, Md, USA, 2nd edition, 2002.
- J. Selman, The Fundamentals of Imaging Physics and Radiobiology, Chares C Thomas, Springfield, Ill USA, 2000.
- CFX®, Version 10.0, User Manual, ANSYS, Inc.
- H. Martin, “Heat and mass transfer between impinging gas jets and solid surfaces,” Advanced Heat Transfer, vol. 13, pp. 1–60, 1977.
- A. F. Mills, Heat Transfer, Prentice Hall, Upper Saddle River, NJ, USA, 2nd edition, 1999.
- K. Jambunathan, E. Lai, M. A. Moss, and B. L. Button, “A review of heat transfer data for single circular jet impingement,” International Journal of Heat and Fluid Flow, vol. 13, no. 2, pp. 106–115, 1992.
- D. H. Lee, J. Song, and M. C. Jo, “The effects of nozzle diameter on impinging jet heat transfer and fluid flow,” Journal of Heat Transfer, vol. 126, no. 4, pp. 554–557, 2004.
- R. Viskanta, “Heat transfer to impinging isothermal gas and flame jets,” Experimental Thermal and Fluid Science, vol. 6, no. 2, pp. 111–134, 1993.
- Z.-H. Liu, T.-F. Tong, and Y.-H. Qiu, “Critical heat flux of steady boiling for subcooled water jet impingement on the flat stagnation zone,” Journal of Heat Transfer, vol. 126, no. 2, pp. 179–183, 2004.
- M. Monde, K. Kitajima, T. Inoue, and Y. Mitsutake, “Critical heat flux in a forced convective subcooled boiling with an impinging jet,” Heat Transfer, vol. 7, pp. 515–520, 1994.
- Y. Mitsutake and M. Monde, “Ultra high critical heat flux during forced flow boiling heat transfer with an impinging jet,” Journal of Heat Transfer, vol. 125, no. 6, pp. 1038–1045, 2003.
- C. H. Kim, A study of an areas X-ray source for diffraction enhanced imaging for clinical and industrial application, M.S. thesis, NC State University, Raleigh, NC, USA, August 2004.
- Solidworks® 3D CAD, User's Guide, Solidworks Corporation, 2007.
- ICEM CFD®, Version 5.1, User Manual, ANSYS, Inc.
- C. H. Kim, A study of monochromatic X-ray area beam for application in diffraction enhanced imaging, Ph.D. dissertation, NC State University, Raleigh, NC, USA, August 2007.
Copyright © 2009 Chang H. Kim et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.