Heat Transfer Performance of Microgroove Back Plate Heat Pipes with Working Fluid and Heating Power

2020 ◽  
Vol 29 (4) ◽  
pp. 982-991
Author(s):  
Yanpeng Wu ◽  
Jie Jia ◽  
Dongmin Tian ◽  
Yew Khoy Chuah
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Performance ◽  
Heat Pipes ◽  
Heating Power ◽  
Working Fluid ◽  
Transfer Performance ◽  
Plate Heat ◽  
Back Plate

Heat Transfer Enhancement of Horizontal Oscillating Heat Pipes With Micro-/Nanostructured Surface

2020 ◽  
Vol 142 (7) ◽  
Author(s):  
Tingting Hao ◽  
Huiwen Yu ◽  
Xuehu Ma ◽  
Zhong Lan
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Performance ◽  
Capillary Flow ◽  
Pure Water ◽  
Heat Pipes ◽  
Contact Angles ◽  
Horizontal Direction ◽  
Working Fluid ◽  
Transfer Performance ◽  
Nanostructured Surface

Abstract For oscillating heat pipes (OHPs) with low turn number (<9) positioned in the horizontal direction, the working fluid could not easily flow back to the evaporator due to the absence of gravity. Based on this, copper OHP with superhydrophilic micro-/nanostructured surface was investigated to enhance the heat transfer performance by introducing additional capillary force. OHPs with six turns were fabricated with bare copper and micro-/nanostructured inner surfaces for comparison. Pure water was used as the working fluid. Contact angles of water on the copper and superhydrophilic surfaces were 36.7 and 0 deg, respectively. The filling ratios of water were 50%, 65%, and 80%, respectively. Thermal resistance and liquid slug oscillations of OHPs were investigated at the heat input ranging from 100 to 380 W. Experimental results showed that OHPs with the superhydrophilic micro-/nanostructured surface showed an enhanced heat transfer performance due to the micro-/nanostructure-induced capillary flow in the horizontal direction. The optimum filling ratio was 65% in this work. The superhydrophilic micro-/nanostructured surface could significantly facilitate the backflow of the working fluid to the evaporator section and accelerate oscillating motions of liquid slugs. With the increasing of 0–70% in slug oscillating amplitude and 0–100% in slug oscillating velocity, micro-/nanostructured OHPs improved the heat transfer performance by up to 10% compared with the copper OHPs due to the wicking effect.

scholarly journals Experimental Investigation of the Thermofluid Characteristics of Shell-and-Plate Heat Exchangers

Energies ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 5304
Author(s):  
Howard Lee ◽  
Ali Sadeghianjahromi ◽  
Po-Lun Kuo ◽  
Chi-Chuan Wang
Keyword(s):  
Heat Transfer ◽  
Friction Factor ◽  
Heat Exchangers ◽  
Heat Transfer Performance ◽  
Reynolds Numbers ◽  
Working Fluid ◽  
Large Contribution ◽  
Transfer Performance ◽  
Shell Side ◽  
Plate Heat

An experimental study regarding the thermofluid characteristics of a shell-and-plate heat exchanger with different chevron angles (45°/45°, 45°/65°, and 65°/65°) with a plate diameter of 440 mm was carried out. Water was used as the working fluid on both sides and the corresponding temperatures ranged from 30–70 °C. The flow rate on the plate or shell side ranged from 10–60 m3/h. The effects of chevron angles on the heat transfer and fluid flow characteristics of shell-and-plate heat exchangers were studied in detail. With regard to the heat transfer performance on the plate side, a higher chevron angle (65°/65°) resulted in a significantly better performance than a low chevron angle (45°/45°). The effect of the chevron angle became even more pronounced at high Reynolds numbers. Unlike the plate side, an increase in the chevron angle had a negative effect on the heat transfer performance of the shell side. Additionally, this opposite effect was more prominent at low Reynolds numbers due to the comparatively large contribution of the manifold. The friction factor increased appreciably with the increase in the chevron angle. However, when changing the chevron angle from 45°/45° to 65°/65°, the increase in the friction factor was about 3–4 times on the plate side while it was about 2 times on the shell side. This can be attributed to the presence of the distribution/collection manifold on the shell side. Empirical correlations for the Nusselt number and friction factor were developed for different combinations of chevron angles with mean deviations of less than 1%.

An Investigation of Flat-Plate Oscillating Heat Pipes

2010 ◽  
Author(s):  
Peng Cheng ◽  
Scott Thompson ◽  
Joe Boswell ◽  
Hongbin Ma
Keyword(s):  
Heat Transfer ◽  
Thermal Resistance ◽  
Flat Plate ◽  
Heat Transfer Performance ◽  
Operating Temperature ◽  
Pure Water ◽  
Heat Pipes ◽  
Copper Plate ◽  
Working Fluid ◽  
Transfer Performance

The heat transfer performance of flat-plate oscillating heat pipes (FP-OHPs) was investigated experimentally and theoretically. Two layers of channels were created by machining grooves on both sides of copper plate, in order to increase the channel number per unit volume. The channels had rectangular cross-sections with hydraulic diameters ranging from 0.762 mm to 1.389 mm. Acetone, water and diamond/acetone, gold/water and diamond/water nanofluids were tested as working fluids. It was found that the FP-OHP’s thermal resistance depended on the power input and operating temperature. The FP-OHP charged with pure water achieved a thermal resistance of 0.078°C/W while removing 560 W with a heat flux of 86.8 W/cm2. The thermal resistance was further decreased when nanofluid was used as the working fluid. A mathematical model predicting the heat transfer performance was developed to predict the effects of channel dimension, heating mode, working fluid and operating temperature on the thermal performance of the FP-OHP. Results presented here will assist in optimization of the FP-OHP and provide a better understanding of heat transfer mechanisms occurring in an OHPs.

scholarly journals Enhanced Heat Transfer Performance of the Tube Heat Exchangers Using Carbon-Based Nanofluids

2021 ◽  
Vol 11 (17) ◽  
pp. 8139
Author(s):  
Shang-Pang Yu ◽  
Yeou-Feng Lue ◽  
Tun-Ping Teng ◽  
Hsiang-Kai Hsieh ◽  
Chia-Cing Huang
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Performance ◽  
Convective Heat Transfer Coefficient ◽  
Synthesis Method ◽  
Gum Arabic ◽  
Heating Power ◽  
Working Fluid ◽  
Transfer Performance ◽  
Tube Heat Exchanger ◽  
Carbon Based

The wet ball milling method was used and a dispersant (gum Arabic) was added to prepare various concentrations (0.05 and 0.2 wt%) of carbon-based nanofluids (CBNFs) by a two-step synthesis method as working fluids for heat exchange. CBNFs were actually used in a tube heat exchanger (THE) for heat transfer performance experiments. The heat transfer performance of water and CBNFs was estimated under different heating powers and flow rates of working fluid. The pump power consumption (Ppe) of 0.05 wt% CBNF was found to be similar to that of water, but the Ppe of 0.2 wt% CBNF was higher than that of water. The convective heat transfer coefficient (HTC) of CBNF in the was higher than that of water, and the HTC of 0.05 wt% and 0.2 wt% CBNF was optimal at the heating power of 120 W and 80 W, respectively. The average HTC of 0.05 wt% CBNFs at 120 W heating power was about 3.33% higher than that of water, while that of 0.2 wt% CBNFs at 80 W heating power was about 4.52% higher than that of water. Considering the Ppe and HTC concomitantly, the best overall system performance was exhibited by 0.05 wt% CBNFs.

An Investigation of Flat-Plate Oscillating Heat Pipes

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
Peng Cheng ◽  
Scott Thompson ◽  
Joe Boswell ◽  
H. B. Ma
Keyword(s):  
Heat Transfer ◽  
Thermal Resistance ◽  
Flat Plate ◽  
Cross Sections ◽  
Heat Transfer Performance ◽  
Heat Pipes ◽  
Power Input ◽  
Copper Plate ◽  
Working Fluid ◽  
Transfer Performance

The heat transfer performance of flat-plate oscillating heat pipes (FP-OHPs) was investigated experimentally and theoretically. Two layers of channels were created by machining grooves on both sides of a copper plate in order to increase the channel number per unit volume. The channels had rectangular cross-sections with hydraulic diameters ranging from 0.762 mm to 1.389 mm. Acetone, water, diamond/acetone, gold/water, and diamond/water nanofluids were tested as working fluids. It was found that the FP-OHP’s thermal resistance depended on the power input and operating temperature. The FP-OHP charged with 0.0003 vol % gold/water nanofluids achieved a thermal resistance of 0.078 K/W while removing 560 W with a heat flux of 86.8 W/cm2. The thermal resistance was further decreased when the nanofluid was used as the working fluid. A mathematical model predicting the heat transfer performance was developed to predict the thermal performance of the FP-OHP. Results presented here will assist in the optimization of the FP-OHP and provide a better understanding of heat transfer mechanisms occurring in OHPs.

scholarly journals CPU COOLING OF DESKTOP COMPUTER BY PARALLEL MINIATURE HEAT PIPES

1970 ◽  
Vol 40 (2) ◽  
pp. 104-109 ◽  
Author(s):  
Chowdhury Md. Feroz ◽  
Ahmed Imtiaz Uddin
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Performance ◽  
Heat Pipes ◽  
Working Fluid ◽  
Transfer Performance ◽  
Copper Block ◽  
Desktop Computer ◽  
Condenser Section ◽  
Working Fluids ◽  
Conventional Cooling

Heat transfer performance of parallel miniature heat pipes (MHPs) of 2.8 mm ID used for cooling desktop computer with different working fluids is presented in this paper. In cooling desktop processors, MHPs consists of six single tube heat pipes connected by a copper block at the evaporator section and fifteen parallel copper sheets used as external fins at the condenser section. Acetone and ethanol are used as working fluid. The copper block is placed above the heat source (on the top of the processor) and the condenser section is provided with external fins perpendicular to the MHPs. Heat transfer characteristics of MHPs using different working fluids are determined experimentally, based on the principle of phase. The experimental results show that, the maximum and steady state temperature of the processor has been reduced significantly by using MHPs with acetone as working fluid instead of conventional cooling fan. Additional use of a fan at the condenser section results much lower processor surface temperature for both working fluids. Key words: CPU cooling; Desktop processor; Heat transfer performance; Miniature Heat Pipe; Working fluid.DOI: 10.3329/jme.v40i2.5351Journal of Mechanical Engineering, Vol. ME 40, No. 2, December 2009 104-109

scholarly journals Testing algorithm for heat transfer performance of nanofluid-filled heat pipe based on neural network

Open Physics ◽  
2020 ◽  
Vol 18 (1) ◽  
pp. 751-760
Author(s):  
Lei Lei
Keyword(s):  
Neural Network ◽  
Heat Transfer ◽  
Heat Pipe ◽  
Heat Transfer Performance ◽  
Volume Fraction ◽  
Heat Pipes ◽  
Transfer Performance ◽  
Analysis Model ◽  
Accurate Analysis ◽  
Testing Algorithm

AbstractTraditional testing algorithm based on pattern matching is impossible to effectively analyze the heat transfer performance of heat pipes filled with different concentrations of nanofluids, so the testing algorithm for heat transfer performance of a nanofluidic heat pipe based on neural network is proposed. Nanofluids are obtained by weighing, preparing, stirring, standing and shaking using dichotomy. Based on this, the heat transfer performance analysis model of the nanofluidic heat pipe based on artificial neural network is constructed, which is applied to the analysis of heat transfer performance of nanofluidic heat pipes to achieve accurate analysis. The experimental results show that the proposed algorithm can effectively analyze the heat transfer performance of heat pipes under different concentrations of nanofluids, and the heat transfer performance of heat pipes is best when the volume fraction of nanofluids is 0.15%.

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