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Advancements in Transcritical Organic Rankine Cycle Technologies: A Comprehensive Review

This literature review focuses on developments in supercritical technologies, specifically transcritical Organic Rankine Cycles (ORCs). It highlights the importance of selecting proper working fluids and optimal heat exchanger design for maximizing efficiency and power output. Key findings include the influence of supercritical conditions on heat transfer properties and the need for further research on heat transfer enhancement mechanisms. The review outlines current goals for ongoing research, such as modeling cycles and investigating thermophysical properties of selected fluids under supercritical conditions.

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Advancements in Transcritical Organic Rankine Cycle Technologies: A Comprehensive Review

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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’ • For T>Tcrit Continuous transition from liquid-like fluid to gas-like fluid (no phase change)

  9. Thermophysical properties • h=f(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

  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 • Mass flow • Flow direction • Pipe diameter

  16. 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.)

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

  18. 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

  19. 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

  20. Thank you for your attention.

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