Flow patterns and heat transfer characteristics of flat plate pulsating heat pipes with various asymmetric and aspect ratios of the channels

Jang, Dong Soo; Lee, Joo Seong; Ahn, Ji Hoon; Kim, Dongwoo; Kim, Yongchan

doi:10.1016/j.applthermaleng.2016.11.189

Cited by 50 publications

(11 citation statements)

References 28 publications

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“…(2) The study of pipeline structure is still in the stage of the pipeline geometry change and the heat transfer performance. The PHP heat transfer performance mechanism of pipeline structure is lacking in-depth description [167,168];…”

Section: Pressure Fluctuations Of the Phpmentioning

confidence: 99%

“…Current Research Insufficient(1) The study of micro-channel layout mainly focuses on the thermal properties of PHP with a certain micro-channel layout design, which does not propose specific design specifications as a reference[166];(2) The study of pipeline structure is still in the stage of the pipeline geometry change and the heat transfer performance. The PHP heat transfer performance mechanism of pipeline structure is lacking in-depth description[167,168];(3) The study of materials and work fluids are not related to manufacturing and cost[169]. The work fluid is believed to be one of the factors that may have the greatest influence on PHP.…”

mentioning

confidence: 99%

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Micro-Channel Oscillating Heat Pipe Energy Conversion Approach of Battery Heat Dissipation Improvement: A Review

Xin

Zhu

2022

Energies

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The application of batteries has become more and more extensive, and the heat dissipation problem cannot be ignored. Oscillating Heat Pipe (OHP) is a good means of heat dissipation. In this paper, the methods to improve the energy conversion and flow thermal performance of micro-channel OHP are studied and summarized. The working principle, heat transfer mechanism, advantages and applications of PHP are also introduced in detail in this study. Proper adjustment of the micro-channel layout can increase the heat transfer limit of PHP by 44%. The thermal resistance of two-diameter channel PHP is 45% lower than that of conventional PHP. The thermal resistance of PHP under uneven heating can be reduced to 50% of the original. PHP pulse heating can alleviate the phenomenon of dryness. Different working fluids have different effects on PHP. The use of graphene nano-fluids as the work medium can reduce the thermal resistance of PHP by 83.6%. The work medium obtained by the mixture of different fluids has the potential to compensate for the defects while inheriting the advantages of a single fluid.

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Section: Pressure Fluctuations Of the Phpmentioning

confidence: 99%

mentioning

confidence: 99%

Micro-Channel Oscillating Heat Pipe Energy Conversion Approach of Battery Heat Dissipation Improvement: A Review

Xin

Zhu

2022

Energies

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“…The results showed that the square microchannel PHP can offer approximately 70% higher maximum allowable heat flux than the circular microchannel PHP at the same hydraulic diameter. Asymmetric channels decreased the thermal resistance of PHP under certain heat inputs [13].…”

Section: Introductionmentioning

confidence: 97%

Experimental investigation of a solar collector integrated with a pulsating heat pipe and a compound parabolic concentrator

Zhang

Wang

et al. 2017

Energy Conversion and Management

105

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The paper reports an experimental investigation of a newly proposed solar collector that integrates a closed-end pulsating heat pipe (PHP) and a compound parabolic concentrator (CPC).The PHP is used as an absorber due to its simple structure and high heat transfer capacity. The CPC has a concentration ratio of 3.4 and can be readily manufactured by three-dimensional printing. The CPC can significantly increase the incident solar irradiation intensity to the PHP absorber and also reduce the heat loss due to the decrease in the area of the hot surface. A prototype of the solar collector has been built, consisting of a PHP absorber bent by 4 mm diameter copper tube, CPC arrayed by 10×2 CPC units with the collection area of 300×427.6 mm 2 , a hot water tank and a glass cover. HFE7100 was utilized as the working fluid at a filling ratio of 40%. The operating characteristics and thermal efficiency of the solar collector were experimentally studied. The steady and periodic temperature fluctuations of the evaporation and condensation sections of the PHP absorber indicate that the absorber works well with a thermal resistance of about 0.26 ℃/W. It is also found that, as the main factor, the thermal performance of the collector decreases with increasing evaporation temperature. The collector apparently shows start-up, operational and shutdown stages at the starting and ending temperatures of 75 °C. When the direct normal irradiance is 800 W/m 2 , the instantaneous thermal efficiency of the solar collector can reach up to 50%.

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“…Similarly, Jang et al [22] changed both the aspect ratio and cross-sectional ratio of the consecutive channels of the PHP. These types of configurations in the relevant studies [21,22], and in some other similar studies provided positive effects, especially regarding operation of the PHP under some critical conditions such as few turns number and horizontal orientation. The basic reason is related to the changing force balance and/or new forces that occurred depending on geometrical configuration.…”

Section: Introductionmentioning

confidence: 99%

“…The basic reason is related to the changing force balance and/or new forces that occurred depending on geometrical configuration. However, all of these types of studies [21,22] used pure fluids and did not use binary mixtures. Thus, there are important gaps in the relevant developing literature.…”

Section: Introductionmentioning

confidence: 99%

Thermal investigation and flow pattern analysis of a closed-loop pulsating heat pipe with binary mixtures

Markal

Varol

2020

J Braz. Soc. Mech. Sci. Eng.

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The present study basically examines thermal performance and relevant flow phenomena of a flat plate closed-loop pulsating heat pipe (FP-CLPHP) filled with binary mixtures. The heat pipe has eight turns, each of which consisting of asymmetrical channel pairs having cross sections as 2 mm × 2 mm and 1 mm × 2 mm (width × height). Binary mixtures are generated as mixtures of ethanol (E) and pentane (P) with different mixing ratios. Mainly, effects of volume mixing ratio (E/P = 1:1, 1:3 and 3:1), vertical (90°) and horizontal orientation (0°) and filling ratio (30% and 60%) on thermal characteristics are investigated under different heat inputs. For examination of flow dynamics, images are obtained by using a high-speed camera at 1000 fps. The results show that variation of volumetric percentage of each component significantly changes thermal performance. Increasing pentane in the mixture improves the thermal performance, such that heat pipe with mixing ratio of E/P = 1:3 can properly operate even at horizontal position. On the other hand, increasing volume of ethanol in mixture leads to collapse of the FP-CLPHP at both orientations (0° and 90°). Generally, the filling ratio of 30% shows better thermal performance. Complex bubble-liquid interactions and dynamics play critical roles on thermal characteristics. Two novel characteristic phenomena are identified for non-uniform PHPs: (1) flooding phenomenon and (2) asymmetrical rapid bubble growth phenomenon. Keywords Thermal performance • Flow visualization • Bubble dynamics • Heat pipe List of symbols A bi Bubble interface area (m 2) A app Shear force acting area (m 2) D h Hydraulic diameter (m) Q i Heat input (W) Q rh Removed heat via cooling water (W) R th Total thermal resistance (°C W −1) T Temperature (°C) Greek symbols Angle between the heat pipe and horizontal position (°) Dynamic viscosity (Pa s)

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Flow patterns and heat transfer characteristics of flat plate pulsating heat pipes with various asymmetric and aspect ratios of the channels

Cited by 50 publications

References 28 publications

Micro-Channel Oscillating Heat Pipe Energy Conversion Approach of Battery Heat Dissipation Improvement: A Review

Micro-Channel Oscillating Heat Pipe Energy Conversion Approach of Battery Heat Dissipation Improvement: A Review

Experimental investigation of a solar collector integrated with a pulsating heat pipe and a compound parabolic concentrator

Thermal investigation and flow pattern analysis of a closed-loop pulsating heat pipe with binary mixtures

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