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Journal of Enhanced Heat Transfer

Impact factor: 0.400

ISSN Print: 1065-5131
ISSN Online: 1563-5074

Journal of Enhanced Heat Transfer

DOI: 10.1615/JEnhHeatTransf.v18.i3.40
pages 221-237

THERMAL CHARACTERISTICS OF CLOSED LOOP PULSATING HEAT PIPE WITH NANOFLUIDS

Hamed Jamshidi
Sharif University of Technology, Department of Mechanical Engineering, Azadi St, Tehran, Iran
Sajad Arabnejad
Sharif University of Technology, Department of Mechanical Engineering, Azadi St, Tehran, Iran
M. Behshad Shafii
Sharif university of technology
Yadollah Saboohi
Sharif University of Technology, Department of Mechanical Engineering, Azadi St, Tehran, Iran

ABSTRACT

In this paper, the effect of different parameters on the thermal operation of a Closed Loop Pulsating Heat Pipe (CLPHP) has been investigated. These parameters include the working fluid, the inclination angle, the filling ratio, and the input heat flux. The effect of nanoparticle mass concentrations has been analyzed as well. It was observed that the CLPHP can decrease thermal resistance up to 11.5 times compared to the same empty copper tube with thermal resistance of 9.4 K/W. Optimum thermal operation for a system with the water-silver nanofluid was achieved at conditions of the 50% filling ratio with thermal resistance of 0.9 K/W, and for the water-titanium oxide system, the optimal conditions were found to be: 40% filling ratio with 0.8 K/W thermal resistance. In addition, the optimum performance for pure water occurs at a filling ratio of 40% with thermal resistance of 1.15 K/W. Employing the nanofluids reduces the thermal resistance by 30% in comparison with pure water. With a decrease in the concentration of nanoparticles in the base fluid, the performance of the system decreases as well, and the total thermal resistance increases. The results showed that the performance of the system improves when the input heat flux to the evaporator increases, but there is a probability of dryout and sudden increase of evaporator temperature in high input heat fluxes.