Influence of different heating types on the pumping performance of a bubble pump
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Abstract
This study presents an experimental investigation of the influence of different heating types on the pumping performance of a bubble pump. A test rig was set up at the Institute of Thermodynamics and Thermal Engineering (ITW), University of Stuttgart. The vertical lift tube is made of copper with an inner diameter of 8 mm and a length of 1.91 m. The working fluid is demineralized water. The test rig offers the possibility to vary the supplied heat flow (0 W − 750 W), the resulting supplied heat flux and the location of the heating. Investigations were carried out using spot heating, partial-length heating and full-length heating. A Coriolis mass flowmeter was successfully implemented which measures the vapor mass flow rate continuously. The improvement of the vapor mass flow rate measurement by using the continuous measurement method compared to a discontinuous one is discussed. Furthermore, the influence of an unstable inlet temperature of the working fluid entering the lift tube on the pumping performance is investigated. The focus of this publication lies on the build-up of the test rig with the measurement setup and the analysis of the pumping performance for the three heating types. The measurement results show a big influence of the heating type on the pumping performance. The lower the relative length of the heating, the higher is the pumping ratio which is defined as the lifted liquid mass flow rate in relation to the generated vapor mass flow rate.
Abbreviations
- A
Amperemeter
- d
Downwards
- DAR
Diffusion absorption refrigerator
- u
Upwards
- V
Voltmeter
Latin symbols
- A
Cross sectional area (m2)
- b
Pumping ratio (−)
- cp
Specific heat capacity at constant pressure (kJ kg−1 K−1)
- D
Diameter (m)
- g
Gravitational acceleration (m s−2)
- ΔH
Height (m)
- Δhv
Specific enthalpy of evaporation (kJ kg−1)
- L
Length (m)
- \( \dot{M} \)
Mass flow rate (kg s−1)
- P
Power (W)
- Δp
Relative pressure (bar)
- \( \dot{Q} \)
Heat flow (W)
- \( \dot{q} \)
Heat flux (W m−2)
- S
Slip ratio (−)
- SR
Submergence ratio (−)
- t
Time (min)
- \( \dot{V} \)
Volumetric flow rate (m3 h−1)
- w
Velocity (m s−1)
- x
Coordinate in flow direction (m)
Greek symbols
- ϑ
Celsius temperature (°C)
- ϑs
Boiling temperature (°C)
- λ
Thermal conductivity (W m−1 K−1)
- ρ
Density (kg m−3)
- \( \overline{\rho} \)
Mean density over length (kg m−3)
- φ
Relative length of heating (−)
Subscripts
- amb
Ambient
- cartr
Cartridges
- disc
Discontinuous
- el
Electric
- evap
Evaporation
- ext
External
- f
Friction
- FDR
Friction dominant regime
- GDR
Gravity dominant regime
- heat
Supplied heat flow
- HX2
Double-pipe heat exchanger 2
- in
At the inlet
- L
Liquid
- LT
Lift tube
- m
Mean
- mass
Related to the mass
- max
Maximum
- min
Minimum
- out
At the outlet
- part
Partial
- preheat
Preheating
- rel
Relative
- res
Reservoir
- TP
Two-phase
- V
Vapor
- vol
Related to the volume
Notes
Acknowledgements
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
Compliance with ethical standards
Conflict of interest
On behalf of all authors, the corresponding author states that there is no conflict of interest.
References
- 1.Gartia MR, Vijayan PK, Pilkhwal DS (2006) A generalized flow correlation for two-phase natural circulation loops. Nucl Eng Des 236:1800–1809CrossRefGoogle Scholar
- 2.Franco A, Filippeschi S (2013) Experimental analysis of Closed Loop Two Phase Thermosyphon (CLTPT) for energy systems. Exp Thermal Fluid Sci 51:302–311CrossRefGoogle Scholar
- 3.Dometic GmbH (2014) Aktuelles. http://www.dometic.com/de/Europe/Germany/ Aktuelles. Accessed November 2014
- 4.Schmid F, Bierling B, Spindler K (2013) Entwicklung einer direkt solarthermisch angetriebenen Diffusions-Absorptionskältemaschine. KI Kälte - Luft - Klimatechnik 49:22–27Google Scholar
- 5.Schmid F, Spindler K (2016) Experimental investigation of the auxiliary gas circuit of a diffusion absorption chiller with natural and forced circulation. Int J Refrig 70:84–92CrossRefGoogle Scholar
- 6.Cattaneo AG (1935) Über die Förderung von Flüssigkeiten mittels der eigenen Dämpfe. Zeitschrift für die gesamte Kälte-Industrie 42:2–52Google Scholar
- 7.Delano A (1998) Design Analysis of the Einstein Refrigeration Cycle. Dissertation, Georgia Institute of TechnologyGoogle Scholar
- 8.Brendel T, Spindler K (2014) Untersuchungen zum Förderverhalten einer Thermosiphonpumpe. Jahrestagung des Deutschen Kälte- und Klimatechnischen Vereins AA.II.1.08Google Scholar
- 9.Shihab AS, Morad AMA (2012) Experimental Investigation of Water Vapor-Bubble Pump Characteristics and its Mathematical Model Reconstruction. Eng Tech J 30:1870–1885Google Scholar
- 10.Vicatos G, Bennett A (2007) Multiple lift tube pumps boost refrigeration capacity in absorption plants. J Energy South Afr 18:49–57Google Scholar
- 11.Chan KW, McCulloch M (2013) Analysis and modelling of water based bubble pump at atmospheric pressure. Int J Refrig 36:1521–1528CrossRefGoogle Scholar
- 12.Rattner AS, Garimella S (2015) Coupling-fluid heated bubble pump generators: Experiments and model development. Science and Technology for the Built Environment 21:332–347CrossRefGoogle Scholar
- 13.Verein Deutscher Ingenieure (VDI) - Gesellschaft Verfahrenstechnik und Chemieingenieurwesen (GVC) (2010) VDI Heat Atlas, 2nd edn. Springer, Berlin, New YorkGoogle Scholar
- 14.Coollaboratory (2016) Coollaboratory Liquid Pro. http://www.coollaboratory.com/product/coollaboratory-liquid-pro. Accessed July 2016