Experimental and numerical study of heat transfer performance of nitrate/expanded graphite composite PCM for solar energy storage

2015 ◽  
Vol 105 ◽  
pp. 272-284 ◽  
Author(s):  
X. Xiao ◽  
P. Zhang ◽  
M. Li
Keyword(s):  
Heat Transfer ◽  
Energy Storage ◽  
Solar Energy ◽  
Heat Transfer Performance ◽  
Numerical Study ◽  
Expanded Graphite ◽  
Transfer Performance ◽  
Graphite Composite ◽  
Solar Energy Storage

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 Numerical study of flow patterns and heat transfer in mini twisted oval tubes

2015 ◽  
Vol 26 (12) ◽  
pp. 1550140 ◽  
Author(s):  
Amin Ebrahimi ◽  
Ehsan Roohi
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Performance ◽  
Numerical Study ◽  
Critical Role ◽  
Reynolds Numbers ◽  
Flow Patterns ◽  
Working Fluid ◽  
Transfer Performance ◽  
Temperature Dependent ◽  
Overall Performance

Flow patterns and heat transfer inside mini twisted oval tubes (TOTs) heated by constant-temperature walls are numerically investigated. Different configurations of tubes are simulated using water as the working fluid with temperature-dependent thermo-physical properties at Reynolds numbers ranging between 500 and 1100. After validating the numerical method with the published correlations and available experimental results, the performance of TOTs is compared to a smooth circular tube. The overall performance of TOTs is evaluated by investigating the thermal-hydraulic performance and the results are analyzed in terms of the field synergy principle and entropy generation. Enhanced heat transfer performance for TOTs is observed at the expense of a higher pressure drop. Additionally, the secondary flow generated by the tube-wall twist is concluded to play a critical role in the augmentation of convective heat transfer, and consequently, better heat transfer performance. It is also observed that the improvement of synergy between velocity and temperature gradient and lower irreversibility cause heat transfer enhancement for TOTs.

Numerical study on the effects of design parameters on the heat transfer performance of coaxial deep borehole heat exchanger

2019 ◽  
Vol 43 (12) ◽  
pp. 6337-6352 ◽  
Author(s):  
Jun Liu ◽  
Fenghao Wang ◽  
Wanlong Cai ◽  
Zhihua Wang ◽  
Qingpeng Wei ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Transfer Performance ◽  
Numerical Study ◽  
Design Parameters ◽  
Transfer Performance ◽  
Deep Borehole ◽  
Borehole Heat Exchanger

scholarly journals Comparison of Heat Transfer Enhancement Techniques in Latent Heat Storage

2020 ◽  
Vol 10 (16) ◽  
pp. 5519 ◽  
Author(s):  
William Delgado-Diaz ◽  
Anastasia Stamatiou ◽  
Simon Maranda ◽  
Remo Waser ◽  
Jörg Worlitschek
Keyword(s):  
Heat Transfer ◽  
Energy Storage ◽  
Latent Heat ◽  
Heat Transfer Performance ◽  
Thermal Power ◽  
High Energy ◽  
High Energy Density ◽  
Evaluation Procedure ◽  
Transfer Performance ◽  
Experimental Conditions

Latent Heat Energy Storage (LHES) using Phase Change Materials (PCM) is considered a promising Thermal Energy Storage (TES) approach as it can allow for high levels of compactness, and execution of the charging and discharging processes at defined, constant temperature levels. These inherent characteristics make LHES particularly attractive for applications that profit from high energy density or precise temperature control. Many novel, promising heat exchanger designs and concepts have emerged as a way to circumvent heat transfer limitations of LHES. However, the extensive range of experimental conditions used to characterize these technologies in literature make it difficult to directly compare them as solutions for high thermal power applications. A methodology is presented that aims to enable the comparison of LHES designs with respect to their compactness and heat transfer performance even when largely disparate experimental data are available in literature. Thus, a pair of key performance indicators (KPI), ΦPCM representing the compactness degree and NHTPC, the normalized heat transfer performance coefficient, are defined, which are minimally influenced by the utilized experimental conditions. The evaluation procedure is presented and applied on various LHES designs. The most promising designs are identified and discussed. The proposed evaluation method is expected to open new paths in the community of LHES research by allowing the leveled-ground contrast of technologies among different studies, and facilitating the evaluation and selection of the most suitable design for a specific application.

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