Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : Condenser

Experimental and Theoretical Study of Vacuum Cooling System

Ahmed A. M. Saleh; Qussai J. Abdul Ghafour; Luay T. Al-Rawi

Engineering and Technology Journal, 2013, Volume 31, Issue 14, Pages 2619-2631

A vacuum cooling system and the parameters which affect on its performance
were studied experimentally and theoretically. For the experimental study the rig was
built up to studying the performance of cooling system in three cases. These cases
are: Cooling water by vacuum only, cooling water in conventional method, and
cooling water by vacuum with condensation.
The experimental results show that the addition of a condenser to the vacuum
cooling system leads to sweep of largest amount of generated vapor, also the time
consumed for the process was decreased. The times required for cooling 45 g from
water from temperature 29oC to 10oC for the three test cases were 4375 second, 3535
second and 263 second, respectively. Vacuum cooling with condenser is a fast
cooling of three systems test, which is about (13.7 times) faster than the system of
natural convection cooling. To work properly, the existence of condenser is very
important in vacuum cooling. It normally removes the large amount of water vapor
generation (about 94%).
For the theoretical study, a computer program was built up by employing the
governing equation to simulate the performance of the vacuum cooling system. The
theoretical results indicate an acceptable agreement with the experimental results.
Also, the results show that the decreasing of condenser temperature causes decreasing
of cooling time according to the equation (t = 0.2031Tcd4 - 2.8958 Tcd3 + 16.406
Tcd2 - 21.104 Tcd + 313.39), and increasing the evaporation surface area leads to
decreasing of cooling time according to the equation (t=1/ (0.0006*Area+0.0005)),
and the increasing of water mass causes in increasing of cooling time according to the
equation (t=7.2667*mass+14).

A Study for the Influence of Change in Ratio of Cross Sectional Area to Constant Perimeter of Thermosyphon's Condenser

Ali D.Salman; Israa S.Ahmed; Waleed Y.Shehab

Engineering and Technology Journal, 2011, Volume 29, Issue 16, Pages 3451-3467

This experimental study investigated the change in cross-sectional area (csa) of thermosyphon's condenser to it's a constant perimeter (RAP) and effect of that at the thermal performance. Geometries shapes deform from circular to elliptical and flat to make a change in csa at a same perimeter of all geometries shapes where a different value of RAP are got. At each RAP a different rate of heat input in evaporator and
different filling ratio of working fluid (distill water) are applied. Threshold angle (working angle) where the condensate of distilled water vapor begin to return to evaporator, this angle are examined with the horizontal level for three geometries shapes (three RAP). The results indicated that the flat two phase closed thermosyphon( FTPCT)(low RAP value) and elliptical two phase closed thermosyphon (ETPCT) had a higher and more stable heat transfer coefficient h (condenser air side) with the high and mid filling ratio from than of the circular two
phase closed thermosyphon( CTPCT). That refer to more useful length of condenser to absorb heat from evaporator and prevent it from causing a rise in temperature. The high filling ratio with low rate of heat level in evaporator lead to unuseful area in thermosyphon's condenser and lowering its pressure, while low filling ratio with high
rate of heat caused a chaotic flow inside TPCT and rising the evaporator and condenser temperatures.