Combination study of operation characteristics and heat transfer mechanism for pulsating heat pipe

• Published in: Applied thermal engineering Vol. 65; no. 1-2; pp. 394 - 402
• Main Authors: Cui, Xiaoyu, Zhu, Yue, Li, Zhihua, Shun, Shende
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01-04-2014; Elsevier
• Subjects: Applied sciences; Characteristics of temperature oscillation; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Heat transfer; Heat transfer mechanism; Pulsating heat pipe; Theoretical studies. Data and constants. Metering; Characteristics of temperature oscillation; Pulsating heat pipe; Heat transfer mechanism; Temperature; Heat pipe; Oscillation; Heated pipe; Heat transfer
• ISSN: 1359-4311
• DOI: 10.1016/j.applthermaleng.2014.01.030

Pulsating heat pipe (PHP) is becoming a promising heat transfer device for the application like electronics cooling. However, due to its complicated operation mechanism, the heat transfer properties of the PHP still have not been fully understood. This study experimentally investigated on a closed-loop PHP charged with four types of working fluids, deionized water, methanol, ethanol and acetone. Combined with the visualization experimental results from the open literature, the operation characteristics and the corresponding heat transfer mechanisms for different heat inputs (5 W up to 100 W) and different filling ratios (20% up to 95%) have been presented and elaborated. The results show that heat-transfer mechanism changed with the transition of operation patterns; before valid oscillation started, the thermal resistance was not like that described in the open literature where it decreased almost linearly, but would rather slowdown descending or even change into rise first before further decreasing (i.e. an inflection point existed); when the heat input further increased to certain level, e.g. 65 W or above, there presented a limit of heat-transfer performance which was independent of the types of working fluids and the filling ratios, but may be related to the structure, the material, the size and the inclination of the PHP.
•The thermal mechanisms altered accordingly with the operation features in the PHP.•Unlike conventional heat pipes, continuous temperature soaring would not happen in the PHP.•Before the oscillation start-up, there existed a heat-transfer limit for the relatively stagnated flow in the PHP.•A limit of thermal performance existed in the PHP at relatively high heat inputs.