4. IINNTTRROODDUUCCTTIIOONN:: Cooling becomes one of the top
technical challenges facing high-tech. industries such as
microelectronics, transportation, manufacturing, metrology, and
vehicles, etc. For reciprocating engine, under full load
conditions, 1025% of the heat supplied by the fuel is lost through
the walls, whereas under part load, the wall heat loss increases to
reach a value higher than 30% at zero load which lead to thermal
loading and mechanical stresses causing fatigue cracking [1]
5. IINNTTRROODDUUCCTTIIOONN:: Localized Nucleate boiling in
very high Temp-erature zones of engine cylinder head Cracks
typically form when a cylinder head undergoes too much thermal
stress Consequently, the wall metal temperature must be less than
about 400 oC for cast iron and 300 oC for aluminum alloy [2]
6. IINNTTRROODDUUCCTTIIOONN ((ccoonntt..)):: Conventional
methods to increase heat flux rates: Traditional coolant fluids
with chemical additives, Extended surfaces such as fins, and
Increasing flow rates. These conventional methods have already
utilized to their maximum potential due to their limitations.
Nanofluids are promising to meet and enhance the challenges
7. IINNTTRROODDUUCCTTIIOONN ((ccoonntt..)):: Nanofluids, coined
by Dr. Choi 1995, are new class of nanotechnology-based heat
transfer fluids that are engineered by stably suspending a small
amount of particles, fibers, or tubes with dimensions on the order
of 1-100 nm. Nanofluids (nano particles mixed with base fluid)
8. Materials for Nanoparticles and Base Fluids: Nanoparticle
materials include Oxide ceramics such as Al2O3, CuO Metal carbides
such as SiC Nitrides such as AlN, SiN Metals such as Al, Cu
Nonmetals such as Graphite, carbon nanotubes Layered such as Al +
Al2O3, Cu + C PCM such as S/S Base fluids include Water Ethylene-
or tri-ethylene-glycols and other coolants Oil and other lubricants
Bio-fluids Polymer solutions Other common fluids
IINNTTRROODDUUCCTTIIOONN ((ccoonntt..))::
9. IINNTTRROODDUUCCTTIIOONN ((ccoonntt..)):: Comparison of the
thermal conductivity of common liquids, polymers and solids
[3]
10. IINNTTRROODDUUCCTTIIOONN ((ccoonntt..)):: Nanofluid
compared to conventional solid-liquid suspensions: High specific
surface area, High dispersion stability , Reduced pumping power for
equivalent heat transfer rate, Reduced particle clogging as
compared to convention slurries , and Adjustable properties,
including thermal conductivity and surface wettability, by varying
particle concentration to suit different applications.
11. Thermo-physical Properties of Nano-fluids: Effect of
Particle VVoolluummee CCoonncceennttrraattiioonn [4] Knf / Kbf aass
%% (Al2O3 in water) EEffffeecctt ooff TTeemmppeerraattuurree [4]
Knf / Kbf aass TT (Al2O3 in water) IINNTTRROODDUUCCTTIIOONN
((ccoonntt..))::
16. PPRREESSEENNTT WWOORRKK:: The used nanofluid: Al2O3/DI
Water (nanoparticles: gamma, 50 nm, 3600 kg/m3) Objectives:
Investigation of the heat transfer enhancement for forced
convection and sub-cooled boiling for the following parameters: 1.
Bulk temperatures (50 : 70 C) 2. Flow velocities (1, 2, 2.5 m/s)
Simulated to engine operating conditions 3. Heat flux, and 4.
Nanofluid concentrations (0 : 3%)
17. PPRREESSEENNTT WWOORRKK ((ccoonntt..)):: Expected results
in the form of graphs:
18. PPRREESSEENNTT WWOORRKK ((ccoonntt..)):: Proposed scheme of
Test rig: 1. Supply tank 2. Main cooling liquid tank 3. Cooling
coil 4. Immersion heater 5. Circulating pump 6. By-pass valve 7.
Flow control valve 8. Flow meter 9. Test duct 10. Test specimen 11.
Bulk liquid TCs 12. Pressure gage 13. Drain valve 14. Cooling water
inlet
19. PPRREESSEENNTT WWOORRKK ((ccoonntt..)):: Test Section:
20. PPRREESSEENNTT WWOORRKK ((ccoonntt..)):: Details of section
A-A:
21. RReeffeerreenncceess:: [1] Hosny Z. Abou-Ziyan. Forced
convection and sub-cooled flow boiling heat transfer in
asymmetrically heated ducts of T-section. Elsevier Science; 2003
[2] Helali AB. Evaluation of propylene glycol and ethylene glycol
engine coolant additives under forced convection and boiling
conditions. Res Eng J, Helwan Univ 2002. [3] Wen D, Lin G, Vafaei
S, Zhang K. Review of nanofluids for heat transfer appli-cations.
Particuology 2009;7:14150