1. 17-9 June 2003Inverse Problem in engineering Symposium Topic FOULING PROBE DEVELOPMENT FOR TUBULAR HEAT EXCHANGERS: A first step Laetitia PEREZ P. TOCHON B. LADEVIE UMR CNRS 2392 J.C. BATSALE UMR CNRS 8508

2. 27-9 June 2003Inverse Problem in engineering Symposium Overview 1.Industrial context 2.The Probe 3.Direct model - theoretical sensitivity analysis 4.Experimental device 5.Experimental results - experimental sensitivity analysis 6.Conclusions

3. 37-9 June 2003Inverse Problem in engineering Symposium Industrial context - heat exchangers in the power and process industries - performance degradation - thermal resistance increase - pressure drop increase - heat coefficient decrease

4. 47-9 June 2003Inverse Problem in engineering Symposium Industrial context Economic problems: - oversizing equipment - high maintenance costs - energy expense It is necessary to: - detect the onset of fouling - follow its development over time  Effectiveness of heat exchangers optimization

5. 57-9 June 2003Inverse Problem in engineering Symposium The Probe

6. 67-9 June 2003Inverse Problem in engineering Symposium Direct model Transient heat equation in cylindrical coordinates: Boundary conditions:

7. 77-9 June 2003Inverse Problem in engineering Symposium Direct model

8. 87-9 June 2003Inverse Problem in engineering Symposium Direct model Finally, the temperature in the Laplace-Fourier space is: The temperature in the real space is: Too many approximations hard to check Harsh industrial conditions Direct model

9. 97-9 June 2003Inverse Problem in engineering Symposium Sensitivity analysis

10. 107-9 June 2003Inverse Problem in engineering Symposium Experimental device

11. 117-9 June 2003Inverse Problem in engineering Symposium Experimental results In clean conditions:

12. 127-9 June 2003Inverse Problem in engineering Symposium Experimental sensitivity analysis The temperature response can be written by: For a little heat transfer coefficient variation: the signal amplitude variation can be calculated by:

13. 137-9 June 2003Inverse Problem in engineering Symposium Experimental sensitivity analysis

14. 147-9 June 2003Inverse Problem in engineering Symposium Experimental results In fouled conditions: Cooling water Air flow with particles Deposit pattern around the probe - Fouling detection after 22h - Fouling thickness after 78h : e fouling = 2 mm t = 22 h t = 35 h t = 40 h t = 70 h t = 78 h 0100200300400500600700800900 100 0 -0.01 -0.005 0 0.005 0.01 0.015 0.02 0.025 0.03 Growing fouling t (s)

15. 157-9 June 2003Inverse Problem in engineering Symposium Conclusions - Fouling probe development -direct model : -sensitivity analysis -experimental device : -experimental sensitivity analysis f(hair) f(e fouling )