Activities per year
Abstract
The prediction offlow pattern transitions is extremely important to understand the coupling of thermal andfluiddynamic phenomena in two phase systems and it contributes to the optimum design of heat exchangers. Twophaseflow regimes have been extensively studied under controlled massflow rate and velocity. On the otherhand, less effort has been spent in the literature on the cases where theflow motion is purely thermally inducedand consequently the massflow rate or the velocity of the phases are not known a priori. In the present work,flow pattern transitions and bubble break-up and coalescence events have been investigated in a passive twophase wickless capillary loop, where the massflow rate is intrinsically not controllable. Modified Froude, Weberand Bond numbers have been introduced, considering the actual acceleration of thefluid and the length of thebubble as merit parameters for the transitions. The proposed nondimensional investigation was developed byanalysing experimental data obtained with ethanol and FC-72, as workingfluids, different heat input levels(from 9 to 24 W) as well as three different gravity levels (through a parabolicflight campaign). A new empiricaldiabaticflow pattern map for accelerated two-phase capillaryflows is presented, together with quantitativecriteria for the calculation of theflow regime transitions, defining the physic limits for the bubble coalescenceand break-up. This kind of new regime maps will be useful to the further development of comprehensive de-signing tools for passive two-phase wickless heat transfer devices.
Original language | English |
---|---|
Article number | 109981 |
Number of pages | 13 |
Journal | Experimental Thermal and Fluid Science |
Volume | 112 |
DOIs | |
Publication status | Published - 1 Nov 2019 |
Keywords
- Pulsating slug flow
- Flow pattern maps
- Visual investigation
- Bubble length
Fingerprint
Dive into the research topics of 'Developing flow pattern maps for accelerated two-phase capillary flows'. Together they form a unique fingerprint.Profiles
-
Anastasios Georgoulas
- School of Arch, Tech and Eng - Principal Lecturer
- Centre for Regenerative Medicine and Devices
- Advanced Engineering Centre
Person: Academic
-
Nicolas Miche
- School of Arch, Tech and Eng - Principal Lecturer
- Centre for Regenerative Medicine and Devices
- Advanced Engineering Centre
Person: Academic
-
Heat Transfer Research, Education and Practice in the UK organised by the UK Heat Transfer Committee
Georgoulas, A. (Presenter)
25 Apr 2019Activity: External talk or presentation › Invited talk
-
68th European Space Agency Parabolic Flight Campaign
Pietrasanta, L. (Participant)
7 Dec 2017Activity: Events › Event