Experimental Research of Heat Transfer Enhancement of the Tube with Disturbed Flow Components Plug-In

2014 ◽  
Vol 960-961 ◽  
pp. 479-484
Author(s):  
Chang Fa Ji ◽  
Rui Qu ◽  
Guo Xin He
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Performance ◽  
Comprehensive Evaluation ◽  
Orthogonal Experiment ◽  
Metal Wire ◽  
High Porosity ◽  
Transfer Performance ◽  
Enhancing Heat Transfer ◽  
Flow Components ◽  
The Given

Based on Field Synergy Principle and orthogonal experiment design, nine arranged metal-wire inserts(that is high porosity porous inserts) is determined to experiment. The results showed that heat transfer performance of the pipe that metal-wire inserts is rooted at the core region of pipe is better than the pipe that metal-wire inserts is rooted at the edge region of pipe., location and curve radian can impact heat exchange significantly. Under the given experimental condition, the heat transfer quantity increased by 120 - 520%, overall heat transfer coefficient increased by 126 - 610%. Through enhancing heat transfer performance evaluation criterion (PEC) comprehensive evaluation, it is concluded that when the Reynolds number Re changes in 338 ~ 6931, the PEC value of 0.89 ~ 5.97.The calculation formula of the drag coefficient is obtained by regression analysis.

Heat Transfer Performance of Micro-Porous Copper Foams with Homogeneous and Hybrid Structures Manufactured by Lost Carbonate Sintering

2015 ◽  
Vol 1779 ◽  
pp. 39-44 ◽  
Author(s):  
Jan Mary Baloyo ◽  
Yuyuan Zhao
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Heat Transfer Performance ◽  
Hybrid Structures ◽  
High Porosity ◽  
Transfer Performance ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Porous Copper

ABSTRACTThe heat transfer coefficients of homogeneous and hybrid micro-porous copper foams, produced by the Lost Carbonate Sintering (LCS) process, were measured under one-dimensional forced convection conditions using water coolant. In general, increasing the water flow rate led to an increase in the heat transfer coefficients. For homogeneous samples, the optimum heat transfer performance was observed for samples with 60% porosity. Different trends in the heat transfer coefficients were found in samples with hybrid structures. Firstly, for horizontal bilayer structures, placing the high porosity layer by the heater gave a higher heat transfer coefficient than the other way round. Secondly, for integrated vertical bilayer structures, having the high porosity layer by the water inlet gave a better heat transfer performance. Lastly, for segmented vertical bilayer samples, having the low porosity layer by the water inlet offered the greatest heat transfer coefficient overall, which is five times higher than its homogeneous counterpart.

Enhancing Heat Transfer of Air-Cooled Heat Sinks Using Piezoelectrically-Driven Agitators and Synthetic Jets

2011 ◽  
Author(s):  
Youmin Yu ◽  
Terrence Simon ◽  
Min Zhang ◽  
Taiho Yeom ◽  
Mark North ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Heat Sink ◽  
Heat Transfer Performance ◽  
Single Channel ◽  
Synthetic Jets ◽  
Heat Sinks ◽  
Transfer Performance ◽  
Transfer Enhancement ◽  
Enhancing Heat Transfer

Air-cooled heat sinks prevail in microelectronics cooling due to their high reliability, low cost, and simplicity. But, their heat transfer performance must be enhanced if they are to compete for high-flux applications with liquid or phase-change cooling. Piezoelectrically-driven agitators and synthetic jets have been reported as good options in enhancing heat transfer of surfaces close to them. This study proposes that agitators and synthetic jets be integrated within air-cooled heat sinks to significantly raise heat transfer performance. A proposed integrated heat sink has been investigated experimentally and with CFD simulations in a single channel heat sink geometry with an agitator and two arrays of synthetic jets. The single channel unit is a precursor to a full scale, multichannel array. The agitator and the jet arrays are separately driven by three piezoelectric stacks at their individual resonant frequencies. The experiments show that the combination of the agitator and synthetic jets raises the heat transfer coefficient of the heat sink by 80%, compared with channel flow only. The 3D computations show similar enhancement and agree well with the experiments. The numerical simulations attribute the heat transfer enhancement to the additional air movement generated by the oscillatory motion of the agitator and the pulsating flow from the synthetic jets. The component studies reveal that the heat transfer enhancement by the agitator is significant on the fin side and base surfaces and the synthetic jets are most effective on the fin tips.

Enhanced Convective Heat Transfer in High Porosity Metal Foams

2014 ◽  
Author(s):  
L. W. Jin ◽  
C. F. Ma ◽  
M. Zhao ◽  
X. Z. Meng ◽  
W. B. Kang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Convective Heat Transfer ◽  
Forced Convection ◽  
Convective Heat ◽  
Heat Transfer Performance ◽  
Heating Surface ◽  
Metal Foams ◽  
High Porosity ◽  
Transfer Performance

Due to the characteristics of large surface area-to-volume ratio and inter-connected ligament structure, open-cell metal foams are promising materials for enhancing heat transfer in forced convection and have been researched for thermal applications in thermal management systems, air-cooled condensers and compact heat sinks for power electronics. However, the tortuous complex flow path inside metal foams leads to relatively higher pressure drop, which requires larger system pumping power. Hence, it is important to study the heat transfer performance of metal foam compared to its flow resistance characteristics. Detailed experimental study of forced convection subjected to constant heat flux in metal foams is conducted in the present paper. The objective of the investigation is to compare the heat transfer performance and hydraulic characteristics of aluminum foams with different pore densities. The tested aluminium foam samples are of 50.0mm (L) × 25.0mm (W) × 12.0mm (H) in geometric dimensions and pore densities are of 5ppi, 10ppi and 40ppi, respectively. Experiments are performed in forced convective heat transfer using deionized water as the cooling fluid. To minimize the heat loss, the test section is built adiabatically with Teflon and polycarbonate materials. The inlet flow velocity, the temperature distribution on the heating surface and the pressure drop across the metal form are measured. Based on the analysis of experimental data, it is found that convective heat transfer performance in high ppi foam is higher than that in low ppi foam, while the pressure drop shows the opposite trend for a given flow rate.

Heat Transfer Characteristics of the Steam Reformer in the HTTR Hydrogen Production System

2004 ◽  
Author(s):  
Tetsuaki Takeda
Keyword(s):  
Heat Transfer ◽  
High Temperature ◽  
Hydrogen Production ◽  
Production System ◽  
Heat Transfer Performance ◽  
Technology Development ◽  
High Porosity ◽  
Transfer Performance ◽  
Metallic Wire ◽  
Steam Reformer

A technology development of a hydrogen production system by nuclear heat is being performed as a heat application system of a high-temperature gas-cooled reactor in the Japan Atomic Energy Research Institute. The objectives of this study are to clarify the heat transfer performance of the steam reformer in the HTTR hydrogen production system and to obtain characteristics of heat transfer and pressure drop in a channel having metallic wire inserts with high porosity. A heat transfer experiment has been performed using a horizontal circular tube. It was found that the heat transfer performance of the method using the metallic wire inserts could be further improved under the high temperature conditions.

10911 Heat transfer performance of air-water heat exchanger inserting metal wire

2015 ◽  
Vol 2015.21 (0) ◽  
pp. _10911-1_-_10911-2_
Author(s):  
Tatsuru OKUBO ◽  
Tetsuaki TAKEDA ◽  
Shumpei FUNATANI
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Transfer Performance ◽  
Metal Wire ◽  
Transfer Performance
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