High heat transfer performance of foam freezing in phase change cold energy storage process

2021 ◽  
Vol 44 ◽  
pp. 103284
Author(s):  
Zhaolei Ding ◽  
Zhaoliang Jiang ◽  
Jiamin Wang
Keyword(s):  
Heat Transfer ◽  
Energy Storage ◽  
Phase Change ◽  
Heat Transfer Performance ◽  
High Heat ◽  
Transfer Performance ◽  
Storage Process ◽  
High Heat Transfer ◽  
Cold Energy

scholarly journals Entropy Generation and Heat Transfer Performance in Microchannel Cooling

Entropy ◽  
2019 ◽  
Vol 21 (2) ◽  
pp. 191 ◽  
Author(s):  
Jundika Kurnia ◽  
Desmond Lim ◽  
Lianjun Chen ◽  
Lishuai Jiang ◽  
Agus Sasmito
Keyword(s):  
Heat Transfer ◽  
Entropy Generation ◽  
Heat Transfer Performance ◽  
Second Law Of Thermodynamics ◽  
High Heat ◽  
Heat Fluxes ◽  
Transfer Performance ◽  
Cooling Channel ◽  
High Heat Transfer ◽  
Microchannel Cooling

Owing to its relatively high heat transfer performance and simple configurations, liquid cooling remains the preferred choice for electronic cooling and other applications. In this cooling approach, channel design plays an important role in dictating the cooling performance of the heat sink. Most cooling channel studies evaluate the performance in view of the first thermodynamics aspect. This study is conducted to investigate flow behaviour and heat transfer performance of an incompressible fluid in a cooling channel with oblique fins with regards to first law and second law of thermodynamics. The effect of oblique fin angle and inlet Reynolds number are investigated. In addition, the performance of the cooling channels for different heat fluxes is evaluated. The results indicate that the oblique fin channel with 20° angle yields the highest figure of merit, especially at higher Re (250–1000). The entropy generation is found to be lowest for an oblique fin channel with 90° angle, which is about twice than that of a conventional parallel channel. Increasing Re decreases the entropy generation, while increasing heat flux increases the entropy generation.

Flow and Heat Transfer Characteristics of Multi-Armed Impinging Jet Using DNS

2019 ◽  
Author(s):  
Kentaro Echigo ◽  
Koichi Tsujimoto ◽  
Toshihiko Shakouchi ◽  
Toshitake Ando
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Performance ◽  
Flow Characteristics ◽  
Impinging Jet ◽  
High Heat ◽  
Impinging Jets ◽  
Transfer Performance ◽  
Velocity Magnitude ◽  
High Heat Transfer ◽  
Flow Phenomena

Abstract A single impinging jet (SIJ) produces a high heat transfer rate around an impinging position on an impinging wall, while the heat transfer performance (HTP) decays increasing the distance from the impinging position. Thus in order to overcome the shortcoming of SIJ: the occurrence of both inhomogeneous heat distribution on the wall and the narrow heating area, multiple impinging jets (MIJ) are generally introduced, however, nonuniformity of heat transfer still occurs. Therefore, the viewpoint of new jet control is required in order to further improvement of the uniformity of heat transfer. On the other hand, blooming jets occur with superimposition of axial and helical excitations on the inlet velocity profile. Blooming jets are characterized by vortex rings moving along branches of separate streams. In previous studies, it is observed that blooming jets change its flow pattern with different frequency ratio of axial to helical, and its mixing and diffusion characteristics. However, there are no studies that observe heat transfer performance of the blooming jet. In this study, we conduct a direct numerical simulation of blooming jet that impinges upon the wall, and investigate its flow characteristics and heat transfer performance. As a control parameter, the distance from the wall is varied. From the view of vortex structures and velocity magnitude, it reveals how the generation of flow phenomena are modulated through the blooming control. Further in order to quantify the heat transfer of the blooming, distributions of mean local Nusselt Number are examined. Compared to the uncontrolled jet, it is confirmed that the uniformity of heat transfer is improved, suggesting that the blooming jets can be expected to be useful for the improvement of uniform heat transfer performance of impinging jets.

Experimental and Numerical Analysis of High Heat Transfer Phenomenon in Minichannel Gaseous Cooling

2006 ◽  
Author(s):  
Kazuo Hara ◽  
Masato Furukawa ◽  
Naoki Akihiro
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Performance ◽  
Flow System ◽  
High Heat ◽  
Transfer Performance ◽  
Channel Inlet ◽  
Two Stage ◽  
Impingement Jet ◽  
Recirculating Flow ◽  
High Heat Transfer

The authors have reported that minichannel flow system had high heat transfer coefficient, the reason of which was investigated experimentally and numerically for single and array minichannels combined with impingement flow system. The diameter D of the channel was 1.27 mm and length to diameter ratio L/D was 5. The minichannel array was so called shower head which was constructed by 19 minichannels located at the apex of equilateral triangle, the side length S of which was 4 mm. Single stage block was used to investigate the heat transfer without impinging flow system. Two stage blocks were used to compose an impingement heat exchanger system with an impingement distance of H. H/D ranged from 1.97 to 7.87. A comparison of heat transfer performance was made between minichannel flow system and impingement jet using the single and two stage heat transfer experimental data. It was found that heat transfer performance of the minichannel was equivalent to that of impingement jet. The mechanism of high heat transfer was studied numerically by the Reynolds averaged Navier-Stokes equation and k-ω turbulence model. The limiting streamline pattern was correlated well to the surface heat flux distribution. The high heat transfer in the single minichannel was achieved by suppressing the development of boundary layer under strong pressure gradient near the channel inlet and by the formation of large recirculating flow system in the downstream plenum of the minichannel exit. These heat transfer mechanisms became dominant when the channel size fallen into the regime of minichannel. For the array of 19 minichannels, the high heat transfer around the channel inlet was also observed clearly in the target plate of the impingement jet where minichannels of second stage were bored to exhaust the fluid of impingement jet.

The Start-Up Performance of Pulsating Heat Pipe With Communicating Pipe at Different Inclination Angles

2019 ◽  
Author(s):  
Fu-Min Shang ◽  
Shi-Long Fan ◽  
Jian-Hong Liu
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Heat Pipe ◽  
Heat Transfer Performance ◽  
Working Fluid ◽  
Transfer Performance ◽  
Pulsating Heat Pipe ◽  
High Heat Transfer ◽  
Start Up ◽  
Inclination Angles

Abstract The pulsating heat pipe (PHP) is a passive cooling device, which has the advantages of simple structure, high heat transfer performance and low production cost. The complex vapor-liquid phase change occurs in the in the initial stage of PHP. In this work, we explore the start-up performance of PHP at different inclination angles and the experiment shows that start-up performance is respectively different when the angles are 0°, 45°, 90°, 135° and 180°. Since the gravitational auxiliary function, the working fluid in the communicating pipe which takes longer time to vaporize change phase earlier than that in PHP’s loop when the angles are 0° and 45°. Nevertheless, when the angle is 90°, the phase change of working fluid in communicating pipe and in the loop occurs at the same time. Meanwhile, the oscillating mode affects the stability of the starting and heat transfer performance of the PHP.

Preparation and Numerical Simulation of Heat Transfer Performance for Methyl Palmitate /Expanded Graphite Phase Change Composite

2020 ◽  
Vol 834 ◽  
pp. 132-138
Author(s):  
Bi Chuan Chi ◽  
Yan Yao ◽  
Su Ping Cui
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Numerical Simulation ◽  
Energy Storage ◽  
Phase Change ◽  
Methyl Palmitate ◽  
Phase Change Materials ◽  
Heat Transfer Performance ◽  
Expanded Graphite ◽  
Transfer Performance

Methyl palmitate (MP) is a promising phase change energy storage material. It features high latent heat, suitable phase change temperature, low degree of supercooling and so on. However, like other organic phase change materials, the common problem of lower thermal conductivity makes it unable to perform better in energy storage. Expanded graphite (EG) has been proven to be high-efficiency for enhancing the thermal conductivity of organic phase change materials. MP/EG phase change composite was prepared and characterized in this research, and the heat transfer performance was numerical simulated by finite element analysis software ABAQUS. Results show that MP can be absorbed into the layered pores of EG, and the stable absorption ratio is 77%. Numerical simulation results reveal that EG can significantly enhance the heat transfer performance of MP. Moreover, EG can decrease the system temperature gradient during phase change process that makes the heat transfer and temperature distribution more uniform.

scholarly journals Study on Testing Methods for the Heat Transfer Performance of Plate Heat Exchangers

2021 ◽  
Vol 245 ◽  
pp. 01048
Author(s):  
Bin Ren ◽  
Xuchen Zhu ◽  
Yannan Du ◽  
Zhe Pu ◽  
Hongliang Lu ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Exchangers ◽  
Heat Transfer Performance ◽  
High Heat ◽  
Plate Heat Exchanger ◽  
Transfer Performance ◽  
Plate Heat ◽  
High Heat Transfer ◽  
Wilson Plot

Plate heat exchangers are new-type compact heat exchangers with high heat transfer efficiency widely used in heating, food, medicine, shipbuilding and petrochemical industries. However, only the laboratory testing can accurately obtain the real heat transfer and flow resistance performance of plate heat exchanger. In this paper, the basic principles of modified Wilson plot method and equal velocity method are firstly introduced. Then the testing system including flow chart and testing instruments are discussed. Finally, contrast experiments using the different two methods are conducted. The results showed that for plate heat exchangers with equal channel, the equal velocity method and modified Wilson plot method can both be used to test the convective heat transfer performance of plate heat exchanger. The equal velocity method is recommended because the deformation of plate is relatively smaller.

Sign in / Sign up

Export Citation Format

Share Document