RT Journal Article
ID 6e9749692c64cbf9
A1 Karthikeyan, V. K.
A1 Khandekar, Sameer
A1 Pillai, B. C. 
T1 INFRARED THERMOGRAPHY OF A CLOSED LOOP PULSATING HEAT PIPE
JF Heat Pipe Science and Technology, An International Journal
JO HPST
YR 2014
FD 0000-00-00
VO 5
IS 1-4
SP 361
OP 368
K1 pulsating heat pipe
K1 temperature oscillations
K1 multiple steady-state
K1 infrared thermography
AB A pulsating heat pipe (PHP) is essentially a non-equilibrium passive two-phase heat transfer device, which also belongs to a special category of wickless heat pipes. This paper focuses on understanding the pulsating heat pipe operation with spatial and temporal measurement of its tube wall temperature by high resolution infrared thermography (IR). In this study, a copper tube PHP is fabricated and investigated under vertical bottom heat mode and horizontal heat modes with varying heat power. DI water is used as a working fluid. The tube wall and fluid temperatures are also simultaneously measured by micro-thermocouples. Based on
these experiments, the different operating regimes are identified, when heat power increases, namely, (i) no
oscillations (ii) start-up and intermittent oscillations (iii) continuous oscillations and (iv) dry-out during the
experiments, which are correlated with the correspoding fluid motion by IR visualization. The overall thermal
resistance and effective thermal conductivity has been estimated at different heat powers. Further, it is observed
that the device exhibits multiple-steady states when operated continuously for an extended period of time. This is the first time when such behaviour is noted in a multi turn PHP. Several important features of PHP operation are
delineated by the thermographic measurements.

PB Begell House
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