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ORCNext – WP4 Development of supercritical technologies

ORCNext – WP4 Development of supercritical technologies. Catternan Tom. ORCNext – WP4 Development of supercritical technologies. Transcritical ORCs – Literature review. Transcritical ORCs. Better thermal matching  driving force LMTD↓  UA↑.

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ORCNext – WP4 Development of supercritical technologies

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  1. ORCNext– WP4Development of supercriticaltechnologies Catternan Tom

  2. ORCNext– WP4Development of supercriticaltechnologies Transcritical ORCs – Literature review

  3. Transcritical ORCs • Better thermal matching  driving force LMTD↓  UA↑ • Best efficiency and highest power output when temperature profile of HS and WF match  lower exergy destruction (Larjola et al.).

  4. Selection of working fluids • Wide range of applications and ranges  no consensus for best working fluid.

  5. Selection of working fluids

  6. Heat exchanger design Influence ORC parameters on HX design (Schuster and Karellas, 2012) • R134a, R227ea and R245fa • Jackson correlation (1979): Water and CO2 • HTC decreases with increasing supercritical pressure and temperature HX area increases • Relatively unknown heat transfer mechanisms around C.P.  need further investigation

  7. ORCNext– WP4Development of supercriticaltechnologies Forced convective heat transfer at supercritical pressures Literature review

  8. Supercritical state • Critical point ‘c’ • Supercritical state • For T>Tcrit Continuous transition from liquid-like fluid to gas-like fluid (no phase change)

  9. Thermophysical properties • (cp, m, r, l, Pr…)=f(T) • Pseudo-critical temperature Tpc= f(p)

  10. Thermophysical properties

  11. Literature overview • Experimental • H2O, CO2, nitrogen, hydrogen, helium, ethane, R22 • Uniform cross section • Circular • Recently: triangular and square • Uniform heat flux  electrically  forced Tw • Different experimental results • Numerical • Only recent

  12. General characteristicsHeat transfer enhancement Maximum HTC • ↓ • ↑ • Due to variation of thermophysical properties (1) Theory (∆) Experimental:= 140±4.4 kg/h; q = 1.44 W/cm² (2) Theory(x) Experimental:= 140±3.1 kg/h; q = 2.73 W/cm² (3) Theory (○) Experimental:= 280±5.6 kg/h; q = 3.32 W/cm² (4 Theory (●) Experimental:= 280±7.8 kg/h; q = 5.20 W/cm² Variation of the heat transfer coefficient with bulk temperature for forced convection in a heated pipe for carbon dioxide of 78.5bar flowing upwards in a 1.0 diameter vertical pipe.

  13. General characteristicsHeat transfer deterioration • Comparison upward and downward flow • Downward  no unusual behaviour • Upward  deterioration Upward flow Downward flow Wall and bulk temperature as a function of the distance along a vertical heated 1.6 cm diameter pipe for water at 245 bar (1.11 pcrit).

  14. General characteristicsHeat transfer deterioration • Comparison upward, downward and horizontal flow (1) Horizontal pipe – upper surface (2) Horizontal pipe – lower surface (3) Vertical pipe – upward flow (4) Bulk fluid temperature Temperature distribution as a function of local bulk enthalpy along heated vertical and horizontal pipes (1.6 cm diameter) for water at 245 bar (= 1.11 pcrit): and

  15. Influence of parameters • Heat flux Left: Ratio of the experimental heat transfer coefficient to the value calculated via the Dittus-Boelter equation;. Right: Wall temperature behaviour for low and high heat fluxes.

  16. Influence of parameters • Heat flux • Mass flow Generalized curves for water at 250bar (Lokshin et al.)

  17. Influence of parameters • Heat flux • Mass flow • Flow direction Comparison of heat transfer between an upward and downward flow for CO2 by Jackson and Evans-Lutterodt

  18. Influence of parameters • Heat flux • Mass flow • Flow direction • Pipe diameter Effect of tube diameter on heat transfer coefficient (Cheng X. et al.)

  19. Correlations • Bringer and Smith (1957) • Miropolsky and Shitsman (1959, 1963) • Petukhov, Krasnoshchekov and Protopopov (1959, 1961, 1979) • Domin (1963) • Bishop (1962, 1965) • Kutateladze and Leontiev (1964) • Swenson (1965) • Touba and McFadden (1966) • Kondrat’ev (1969) • Ornatsky et al. (1970) • Yamagata (1972) • Yaskin et al. (1977) • Jackson (1979) • Yeroshenko and Yaskin (1981) • Watts (1982) • Bogachev et al. (1983) • Griem (1995, 1999) • … Heat transfer coefficient for supercritical water according to different correlations (Cheng X. et al.)

  20. ORCNext– WP4Development of supercriticaltechnologies Goals and planning for the next 6 months

  21. Transcritical ORCs • Finish literature study (± 10 more papers to read) • Model sub – and transcritical cycle (together with WP1) • Choose parameter range • Compare both cycles using the Performance Indicators for several working fluids • Check influence of the variable parameters on the objective functions  sensitivity • Make a list of 3 working fluids, which will be used in the experimental setup

  22. Supercritical forced convection heat transfer • Investigate thermophysical properties under supercritical conditions of the selected working fluids (via REFPROP or EES) • Finish literature study • Deteriorated and improved heat transfer regimes • Onset deterioration • Correlations • Fundamental understanding heat transfer and occurring flow - Test setup have to be built: • Prepare setup • Choose materials • Order

  23. Thank you for your attention.

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