Investigation of Transient Temperature Oscillations of a Propylene Loop Heat Pipe

2001 ◽  
Author(s):  
José I. Rodriguez ◽  
Arthur Na-Nakornpanom
Keyword(s):  
Heat Pipe ◽  
Transient Temperature ◽  
Loop Heat Pipe ◽  
Temperature Oscillations

A Flow Visualization Study on the Temperature Oscillations Inside a Loop Heat Pipe With Flat Evaporator

2013 ◽  
Author(s):  
Dongchuan Mo ◽  
Guansheng Zou ◽  
Shushen Lu ◽  
L. Winston Zhang
Keyword(s):  
Flow Visualization ◽  
Heat Pipe ◽  
Temperature Oscillation ◽  
Heating Power ◽  
Working Fluid ◽  
Loop Heat Pipe ◽  
Interface Motion ◽  
Temperature Oscillations ◽  
Flat Evaporator ◽  
Compensation Chamber

This paper presents a flow visualization study on the temperature oscillations inside a loop heat pipe in order to gain a better understanding of its heat transfer characteristics. A flat loop heat pipe (FLHP) with a flat evaporator instead of a typical cylindrical evaporator was built using copper as the shell and water as the working fluid. An experimental setup was designed by using the transparent material instead of copper in some parts of the FLHP. The experiment results showed that there were at least three different flow patterns in the vapor line as the heating power increased. The temperatures in different locations of the loop oscillated even when the heating power was kept constant. The largest amplitude of the temperature oscillation in the loop was located at the condenser outlet. It was found that the temperature oscillation at the condenser outlet could be divided into two types, one with smaller amplitudes and the other with larger amplitudes. The smaller amplitude temperature oscillations were always there when the heating power was increased step by step, while the larger amplitude temperature oscillations would disappear initially and show up later. Finally, the location of the vapor/liquid interface inside the condenser varied with the temperature oscillations, resulting in liquid/vapor interface motion in the compensation chamber.

Steady-State and Transient Performance of a Miniature Loop Heat Pipe

2005 ◽  
Author(s):  
Yuming Chen ◽  
Manfred Groll ◽  
Rainer Mertz ◽  
Yu. F. Maydanik ◽  
S. V. Vershinin
Keyword(s):  
Steady State ◽  
Heat Pipe ◽  
Electronics Cooling ◽  
Consumer Electronics ◽  
Outer Diameter ◽  
Loop Heat Pipe ◽  
Operating Characteristics ◽  
Evaporator Temperature ◽  
Temperature Oscillations ◽  
Compensation Chamber

A series of tests have been carried out with a miniature loop heat pipe (mLHP), which has been developed for consumer electronics cooling, for horizontal and four vertical orientations under different sink temperatures. The mLHP has a cylindrical evaporator of 5 mm outer diameter and 29 mm length. The steady-state operating characteristics are similar for different orientations except for the orientation where the evaporator is above the compensation chamber. At an evaporator temperature of 75 °C, an evaporator heat load up to 70 W can be reached with thermal resistance of about 0.2 °C/W. The transient behavior of the mLHP is studied in detail. In general, the mLHP can be started up with very low power input (5 W). Big temperature oscillations in the liquid line were found in many cases, however, the temperature oscillations in the evaporator are minimum. The orientations greatly influence the operating characteristics of the mLHP. At least for the horizontal orientation, the overall performance of the tested mLHP is satisfying.

Experimental Analysis and FEM Simulation of Novel Finned Loop Heat Pipe

2014 ◽  
Vol 925 ◽  
pp. 481-485 ◽  
Author(s):  
Prem Gunnasegaran ◽  
Mohd Zulkifly Abdullah ◽  
Norshah Hafeez Shuaib
Keyword(s):  
Thermal Resistance ◽  
Heat Pipe ◽  
Heat Input ◽  
Transient Temperature ◽  
Loop Heat Pipe ◽  
Water Tank ◽  
Air Velocity ◽  
Transparent Plastic ◽  
Total Thermal Resistance ◽  
Steady State Condition

Experiments are conducted to investigate heat transfer characteristics of finned loop heat pipe (FLHP) for heat input range from 20 W to 100 W. The experiments are carried out by manufacturing the FLHP, which the setup consists of a water tank with pump, a flat evaporator, condenser installed with two pieces of fans and air flow fins, two transportation lines (vapor and liquid lines), copper pipe sections for attachment of the thermocouples and power supply. The unique of the current experimental setup is the vapor and liquid lines of FLHP are made of transparent plastic tube to visualize the fluid flow patterns. In this study, the total thermal resistance (Rt) is estimated for both natural and forced convection modes under steady state condition, by varying the air velocity from 2 m/s to 10 m/s. The coolant velocity and heat input to achieve minimumRtare found out and the corresponding effective thermal conductivity is calculated. The transient temperature distribution in the FLHP is also observed. The experimental observations are verified by simulation using Finite Element Method (FEM). The results reveal that the air velocity and power input have significant effects on the performance of FLHP. As the heat input and air velocity increase, total thermal resistance decreases.

EXPERIMENTAL COMPARISON OF LOOP HEAT PIPE PERFORMANCE WITH VARIOUS EVAPORATOR DESIGNS

2014 ◽  
Vol 5 (1-4) ◽  
pp. 287-294
Author(s):  
S. Ouenzerfi ◽  
T. Barreteau ◽  
C. Petit ◽  
Valerie Sartre ◽  
Jocelyn Bonjour ◽  
...  
Keyword(s):  
Heat Pipe ◽  
Experimental Comparison ◽  
Loop Heat Pipe
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