IMPROVEMENT OF A CAPACITY OF A PLATE FIN TUBED HEAT EXCHANGER BY THERMAL ANALYSIS CONSIDERING THERMAL INTERACTION BETWEEN PIPES BY HEAT CONDUCTION IN FINS

1994 ◽  
Author(s):  
K. Kaga ◽  
K. Yamada ◽  
S. Kotoh ◽  
M. Takeshita ◽  
G. Yamanaka
Keyword(s):  
Thermal Analysis ◽  
Heat Conduction ◽  
Heat Exchanger ◽  
Thermal Interaction

A numerical study on the internal heat leak mechanisms in a variable property three-stream heat exchanger

2021 ◽  
pp. 095765092110149
Author(s):  
Yasser Shafiei-alamooti ◽  
Ali Ashrafizadeh
Keyword(s):  
Heat Transfer ◽  
Thermal Analysis ◽  
Heat Conduction ◽  
Heat Exchanger ◽  
Temperature Distribution ◽  
Heat Exchangers ◽  
Numerical Study ◽  
Internal Heat ◽  
Heat Leak ◽  
Maximum Heat

Heat leakage mechanisms need to be addressed in the thermal analysis of multi-stream heat exchangers due to their effects on the intended heat transfer between the streams. In this paper, multi-dimensional heat transfers between various fluid streams and also between the fluid and solid parts of a three-stream plate-fin heat exchanger is numerically modeled considering the variation of thermo-physical properties of both solid and fluid parts. All internal heat leak mechanisms, i.e. longitudinal heat conduction, transverse bypass through fins, and heat transfer reversal in a stream are taken into consideration. The distribution of longitudinal heat conduction along the stream’s separating plates (plates) is also explored. It is shown that the longitudinal heat conduction depends strongly on the variation of properties in some flow arrangements. For such cases, the plates experience areas with relatively low temperature, and a new longitudinal heat conduction, mainly induced by property variation, is identified and presented. This induced longitudinal conduction is close to 1% of the maximum heat exchange between the streams in this study. Another interesting result is that the longitudinal temperature distribution in the plates does not necessarily follow the temperature distribution along the nearby streams due to the entrance effects and unbalanced heat capacity rates. Numerical results show that property variations affect all of the thermal leakage phenomena and, therefore, need to be considered in the modeling and thermal analysis of multi-stream heat exchangers.

Role of Thermal-Interaction Between Aggregated Particles in Thermal Conductivity Enhancement of Nanofluids

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
Jae Sik Jin ◽  
Joon Sik Lee
Keyword(s):  
Thermal Conductivity ◽  
Thermal Analysis ◽  
Heat Conduction ◽  
Effective Thermal Conductivity ◽  
Volume Fraction ◽  
Thermal Flux ◽  
Linear Chain ◽  
Field Variation ◽  
Thermal Interaction

This study investigates the role of thermal-interaction (TI) between aggregated particles (APs) on the enhanced thermal conductivity of nanofluids. With the assumption of configurations of linear chain-like aggregates in the direction transverse to the thermal flux, two-dimensional heat conduction is considered for estimation of the effective thermal conductivity of regular arrays, which is separated into three components, namely, no thermal-interaction (NTI) effect, longitudinal thermal-interaction (LTI) effect, and transverse thermal-interaction (TTI) effect. We have obtained a solution to the 1D confine case of APs, and a thermal analysis is carried out for different confine systems to investigate their relatively quantitative assessments of thermal contribution to the enhanced effective thermal conductivity using the first-order approximation. We show that these effects are represented as a function of ϕ (where ϕ is the volume fraction of APs) for engineering purposes. It is also found that TI contribution to the enhanced thermal conduction reaches up to around 87.5% when APs contact with each other and that TTI has an important role in the range 0.3785 ≤ ϕ ≤ 0.7031 due to the confine effect of field-variation caused by transversely bidirectional thermal-interactions. When ϕ > 0.7031, LTI effect again plays key role in heat conduction in nanofluid systems owing to closed packing of APs. Consequently, to achieve energy-efficient heat transfer nanofluids that are required in many industrial applications, both APs' distribution configuration and APs' volume fraction have to be considered in the thermal analysis of nanofluids.

THERMAL ANALYSIS OF HEAT EXCHANGER WITH SUPERCRITICAL PRESSURE CO2

2018 ◽  
Author(s):  
Jiangfeng Guo ◽  
Xiulan L. Huai ◽  
Keyong Cheng ◽  
Xinying Cui ◽  
Haiyang Zhang
Keyword(s):  
Thermal Analysis ◽  
Heat Exchanger ◽  
Supercritical Pressure

The Effect of Longitudinal Heat Conduction on Periodic-Flow Heat Exchanger Performance

1964 ◽  
Vol 86 (2) ◽  
pp. 105-117 ◽  
Author(s):  
G. D. Bahnke ◽  
C. P. Howard
Keyword(s):  
Heat Conduction ◽  
Heat Exchanger ◽  
Heat Exchangers ◽  
Zero Element ◽  
General Purpose ◽  
Periodic Flow ◽  
Gas Streams ◽  
Flow Heat ◽  
Area Use ◽  
Significant Figures

A numerical finite-difference method of calculating the effectiveness for the periodic-flow type heat exchanger accounting for the effect of longitudinal heat conduction in the direction of fluid flow is presented. The method considers the metal stream in crossflow with each of the gas streams as two separate but dependent heat exchangers. To accommodate the large number of divisions necessary for accuracy and extrapolation to zero element area, use was made of a general purpose digital computer. The values of the effectiveness thus obtained are good to four significant figures while those values for the conduction effect are good to three significant figures. The exchanger effectiveness and conduction effect have been evaluated over the following range of dimensionless parameters. 1.0⩾Cmin/Cmax⩾0.901.0⩽Cr/Cmin⩽∞1.0⩽NTU0⩽1001.0⩾(hA)*⩾0.251.0⩾As*⩾0.250.01⩽λ⩽0.32

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