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Condensation in mini- and microchannels

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Presentation on theme: "Condensation in mini- and microchannels"— Presentation transcript:

1 Condensation in mini- and microchannels
Hussein Dhanani Sebastian Schmidt Christian Metzger Assistent: Marcel Christians-Lupi I present to you Stephano Nebuloni, and I’m Anthony Servonet, and we’ll speak about the “microchannel flow boiling correlations and 3-zones model”. On this project, we also compared these model to recent published results. XX December 2007 Heat and Mass Transfer Laboratory

2 Heat and Mass Transfer Laboratory
Structure Introduction to condensation in microchannels Pressure drop Prediction models Friedel (1979;1980) Chen (2001) Wilson (2003) Cavallini (2001;2002) Garimella (2005) Comparison with experimental data Conclusion Heat and Mass Transfer Laboratory

3 Heat and Mass Transfer Laboratory
Structure Heat transfer Prediction models Shah (1979) Dobson & Chato (1998) Cavallini (2002) Bandhauer (2005) Comparison with experimental data Conclusions Questions Heat and Mass Transfer Laboratory

4 Heat and Mass Transfer Laboratory
Pressure drop Common parameters used by several correlations Liquid Reynolds number Vapor Reynolds number Liquid-only Reynolds number Vapor-only Reynolds number Heat and Mass Transfer Laboratory

5 Heat and Mass Transfer Laboratory
Pressure drop Common parameters used by several correlations Single-phase friction factor (smooth tube) Single-phase pressure gradients Heat and Mass Transfer Laboratory

6 Pressure drop prediction models
Friedel (1979;1980) Considered Parameters Liquid only single-phase pressure gradient Liquid only and vapor only friction factor Fluid and geometric properties Heat and Mass Transfer Laboratory

7 Pressure drop prediction models
Friedel (1979;1980) Heat and Mass Transfer Laboratory

8 Pressure drop prediction models
Chen (2001) Modification of the Friedel correlation by adding two-phase multiplier Considered Parameters Two-phase pressure gradient by Friedl We, Bo, Re_v, Re_lo Heat and Mass Transfer Laboratory

9 Pressure drop prediction models
Chen (2001) Heat and Mass Transfer Laboratory

10 Pressure drop prediction models
Cavallini (2002) Modification of the Friedel correlaction by changing several parameter definitions Considered Parameters Liquid only single-phase pressure gradient Liquid only and vapor only friction factor Fluid and geometric properties Heat and Mass Transfer Laboratory

11 Pressure drop prediction models
Cavallini (2002) Friedel Heat and Mass Transfer Laboratory

12 Pressure drop prediction models
Cavallini (2002) Heat and Mass Transfer Laboratory

13 Heat transfer prediction models
Cavallini et al. (2002) Applicable for annular regime only Considered Parameters Pressure drop Dimensionless film thickness Dimensionless temperature Re, Pr Fluid and geometric properties Range / applicability D = 8 mm R134a and R410a 100 < G < 750 kg/m2s 30 < Tsat < 50°C - Own data and database from others used for correlations Heat and Mass Transfer Laboratory

14 Heat transfer prediction models
Calculation of the shear stress Dimensionless film thickness Heat and Mass Transfer Laboratory

15 Heat transfer prediction models
Dimensionless temperature Heat transfer coefficient Heat and Mass Transfer Laboratory

16 Heat and Mass Transfer Laboratory
Heat transfer Graph analysis for R134a With increasing mass flux the heat transfer coefficient increases G=175 kg/m2s G=400 kg/m2s D=2.75mm, Tsat=35°C Heat and Mass Transfer Laboratory 16

17 Heat and Mass Transfer Laboratory
Heat transfer Graph analysis for R410a With increasing mass flux the heat transfer coefficient increases G=175 kg/m2s G=400 kg/m2s D=2.75mm, Tsat=35°C Heat and Mass Transfer Laboratory 17


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