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Heat Pipe Science and Technology, An International Journal

ISSN Imprimir: 2151-7975
ISSN On-line: 2151-7991

Archives: Volume 1, 2010 to Volume 8, 2017

Heat Pipe Science and Technology, An International Journal

DOI: 10.1615/HeatPipeScieTech.v5.i1-4.400
pages 361-368

INFRARED THERMOGRAPHY OF A CLOSED LOOP PULSATING HEAT PIPE

V. K. Karthikeyan
Department of Mechanical Engineering, Karunya University, Coimbatore- 641114, India; Department of Mechanical Engineering, Sri Ramakrishna Engineering College, Coimbatore-641022, India
Sameer Khandekar
Department of Mechanical Engineering, Indian Institute of Technology Kanpur, Kanpur (UP) 208016, India
B. C. Pillai
Karunya University, Karunya Nagar, Coimbatore-641114, India

RESUMO

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.