INTERNAL FLOW PATTERN AND HEAT TRANSPORT PERFORMANCE OF AN OSCILLATING HEAT PIPE WITH GROOVED CHANNELS

2015 ◽  
Vol 22 (1-3) ◽  
pp. 81-96
Author(s):  
Kazusa Abiko ◽  
Akira Murata ◽  
Hiroshi Saito ◽  
Kaoru Iwamoto
Keyword(s):  
Heat Pipe ◽  
Flow Pattern ◽  
Heat Transport ◽  
Internal Flow ◽  
Oscillating Heat Pipe

Experimental Investigation of Ultrasonic Frequency Effect on an Oscillating Heat Pipe

2016 ◽  
Author(s):  
Nannan Zhao ◽  
Benwei Fu ◽  
Hongbin Ma ◽  
Fengmin Su
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Heat Transport ◽  
Frequency Effect ◽  
Ultrasonic Frequency ◽  
Sound Effect ◽  
Oscillating Heat Pipe ◽  
Ultrasonic Sound ◽  
Heat Transfer Capacity ◽  
Heat Transport Capability

The heat transport capability in an oscillating heat pipe (OHP) significantly depends on the oscillating frequency. An external frequency directly affects the natural frequency in the system. In this investigation, the ultrasound sound effect on the heat transport capability in an OHP was conducted with focus on the ultrasonic frequency effect on the oscillating motion and heat transfer capacity in an OHP. The ultrasonic sound was applied to the evaporating section of the OHP by using the electrically-controlled piezoelectric ceramics. The heat pipe was tested with or without the ultrasonic sound with different frequencies. In addition, the effects of operating temperature, heat load from 25 W to 150 W were investigated. The experimental results demonstrate that the heat transfer capacity enhancement of the OHP depends on the frequency of the ultrasound field, and there exists an optimum combination of the frequencies which will lead to the largest enhancement of the heat transfer capacity of the OHP.

Visualization of an Oscillating Heat Pipe with Hydraulic Diameter Far Exceeding the Conventional Maximum Hydraulic Diameter

2020 ◽  
Vol 142 (3) ◽  
Author(s):  
Yulong Ji ◽  
Lilin Chu ◽  
Chunrong Yu ◽  
Zongyu Wang ◽  
Hongbin Ma
Keyword(s):  
Heat Pipe ◽  
Flow Pattern ◽  
Bubbly Flow ◽  
Research Work ◽  
Filling Ratio ◽  
Hydraulic Diameter ◽  
Working Fluid ◽  
Oscillating Heat Pipe ◽  
Fundamental Research ◽  
Small Bubbles

Abstract For an oscillating heat pipe (OHP), the hydraulic diameter must be sufficiently small so that vapor plug and liquid slug can be formed by the capillary action. Therefore, the hydraulic diameter should not exceed a critical value named maximum hydraulic diameter (MHD). In the current research, a glass OHP with a hydraulic diameter of 6 mm was fabricated, and ethanol was used as the working fluid (Figs. 1 and 2). With a hydraulic diameter far exceeding the maximum hydraulic diameter (MHD) defined by dh,max≤{2σBo[(ρl−ρv)g]}1/2, the OHP can function. But the flow pattern is very different from that with a diameter smaller than the MHD, and depends on the filling ratio. When the OHP is charged with a higher filling ratio, the flow pattern is from the bubbly flow to the slug flow as shown in Fig, 3. When the charging ratio is low, the dispersed bubbly flow with many small bubbles generated on the surface was observed, and the dispersed bubbly flow was directly transformed into the annular flow as shown in Fig. 4. [This research work was supported by National Natural Science Foundation of China under Grant No. 51876019, the Preresearch of General Armament Department (6140922011310), LiaoNing Revitalization Talents Program (XLYC1807117), and the Fundamental Research Funds for the Central Universities of China under Grant No.3132019331.]

Experimental Investigation of a Three-Layer Oscillating Heat Pipe

2014 ◽  
Vol 136 (5) ◽  
Author(s):  
C. D. Smoot ◽  
H. B. Ma
Keyword(s):  
Thermal Conductivity ◽  
Experimental Investigation ◽  
Heat Pipe ◽  
Effective Thermal Conductivity ◽  
Heat Transport ◽  
Total Power ◽  
Oscillating Heat Pipe ◽  
Layer Effect ◽  
Layering Effect ◽  
Heat Transport Capability

An experimental investigation of a compact, triple-layer oscillating heat pipe (OHP) has been conducted to determine the channel layer effect on the heat transport capability in an OHP. The OHP has dimensions 13 mm thick, 229 mm long, and 76 mm wide embedded with two-independent closed loops forming three layers of channels. The unique design of the investigated OHP can be readily used to explore the channel layering effect on the heat transport capability in the OHP. The experimental results show that the addition of channel layers can increase the total power and at the same time, it can increase the effective thermal conductivity of the OHP. When the OHP switches from one layer of channels to two layers of channels, the highest effective thermal conductivity can be increased from 5760 W/mK to 26,560 W/mK. At the same time, the dryout limit can be increased. With three layers of channels, the OHP investigated herein can transport a power up to 8 kW with a heat flux level of 103 W/cm2 achieving an effective thermal conductivity of 33,170 W/mK.

Study on a neon cryogenic oscillating heat pipe with long heat transport distance

2017 ◽  
Vol 54 (6) ◽  
pp. 1721-1727 ◽  
Author(s):  
Qing Liang ◽  
Yi Li ◽  
Qiuliang Wang
Keyword(s):  
Heat Pipe ◽  
Heat Transport ◽  
Oscillating Heat Pipe ◽  
Transport Distance
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