Heat exchanger is an important device in the industry for cooling or heating process. To increase the efficiency of heat exchanger, nanofluids are used to enhance the convective heat . transfer relative to the base fluid. - Al2O3/water nanofluid is used as cold stream in the shell and double concentric tube heat exchanger counter current to the hot stream basis oil. These nanoparticles were of particle size of 40 nm and it was mixed with a base fluid (water) at volume
concentrations of 0.002% and 0.004%. The results showed that each of Nusselt number and overall heat transfer coefficient increased as nanofluid concentrations increased. The pressure drop of nanofluid increased slightly than the base fluid because of the low concentration used.
Study and Analysis of Concentric Shell and Double Tube Heat Exchanger Using - Al 2 O 3 Nanofluid
heat exchanger
heat transfer
nanofluids
Nusselt number.
Publication Date
Mon Nov 01 2010
Journal Name
Al-nahrain Journal Of Science
Chemical Elements Diffusion in the Solar Interior
The standard solar model and equation of state have been used to study relative diffusion of Hydrogen and Helium in the present time for solar interior
as a function of distance and depth from the center of the star. The effects of temperature and density on diffusion velocity for these chemical elements have been explaned.
It is found that heat flow which is arising from these reactions leads to an increase in helium diffusion velocity
while the temperature and density leading to a decrease in Hydrogen diffusion velocity. This means that Hydrogen behaves inversely with that for helium does through these reactions. Accordingly
diffusion percentages for Hydrogen
Helium and other Heavy Elements could be determined for the main sequence stars and white dwarf stars.