Comparison of steady state and transient methods for measurement of local heat transfer in plate fin-tube heat exchangers using liquid crystal thermography with radiant heating

1999 ◽  
Vol 42 (1) ◽  
pp. 1-12 ◽  
Author(s):  
R.E. Critoph ◽  
M.K. Holland ◽  
M. Fisher
Keyword(s):  
Heat Transfer ◽  
Liquid Crystal ◽  
Steady State ◽  
Heat Exchangers ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Radiant Heating ◽  
Liquid Crystal Thermography ◽  
Transient Methods ◽  
Fin Tube

Experimental Study of Heat Transfer Characteristics of a Bluff Body Interacting With a Rib by Using Liquid Crystal Thermography

2013 ◽  
Author(s):  
Zahra Ghorbani-Tari ◽  
Lei Wang ◽  
Bengt Sunden
Keyword(s):  
Heat Transfer ◽  
Liquid Crystal ◽  
Cross Section ◽  
Bluff Body ◽  
Rectangular Cross Section ◽  
Flow Direction ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Upstream Region ◽  
Liquid Crystal Thermography

In the present study, the effects of a single rib on the local heat transfer around a bluff body are examined by using the steady state liquid crystal technique. By varying the spacing between the bluff body and the rib, the interaction between the rib and the bluff body can be controlled. The bluff body is oriented vertically towards the flow direction and spans the whole height of the channel. The bluff body has a rectangular cross-section (height b = 80 mm, width 40 mm) while the rib has a square cross-section (rib height e = 10 mm, rib width 10 mm). The rib is placed in the upstream region of the bluff body either by a spacing L = 100 and 50 mm to yield non-dimensional spacing to rib height ratios L/e = 10 and 5 respectively. Here, the re-attachment length (xR) for a single rib is about 7.5e. The values of the Reynolds number based on the channel hydraulic diameter (Dh) are 55,000 and 89,000. The experimental results revealed that the presence of the rib at L/e = 10 has a more pronounced effect on the enhancement of the heat transfer upstream region of the bluff body. The effect of different L/e on the local Nu number distribution in the wake of the bluff body is small.

Local Heat Transfer Measurements Using Liquid Crystal Thermography Technique

2006 ◽  
Vol 326-328 ◽  
pp. 1295-1300 ◽  
Author(s):  
Dae Hee Lee ◽  
Chang Yul Lim ◽  
Min Hyon Jeon ◽  
Moon Kyoung Kim ◽  
Sung Bong Park ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Liquid Crystal ◽  
Color Change ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Heat Transfer Fluid ◽  
Thermochromic Liquid Crystal ◽  
Flow Problems ◽  
Liquid Crystal Thermography ◽  
Nusselt Numbers

The micro-encapsulated thermochromic liquid crystal has been used for the surface temperature measurement using its color change with heat. There are exciting new opportunities to apply this liquid crystal to the investigation of important and interesting heat transfer/fluid flow problems. The various techniques of using liquid crystal for the measurement of the local Nusselt numbers in very complex geometries are presented in this paper.

Local Heat Transfer Measurements Using Liquid Crystal Thermography Technique

2006 ◽  
pp. 1295-1300
Author(s):  
Dae Hee Lee ◽  
Chang Yul Lim ◽  
Min Hyon Jeon ◽  
Moon Kyoung Kim ◽  
Sung Bong Park ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Liquid Crystal ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Liquid Crystal Thermography
Sign in / Sign up

Export Citation Format

Share Document