Entropy generation analysis of nanofluid flow in a circular tube subjected to constant wall temperature

2012 ◽  
Vol 39 (8) ◽  
pp. 1169-1175 ◽  
Author(s):  
K.Y. Leong ◽  
R. Saidur ◽  
T.M.I. Mahlia ◽  
Y.H. Yau
Keyword(s):  
Entropy Generation ◽  
Wall Temperature ◽  
Circular Tube ◽  
Nanofluid Flow ◽  
Constant Wall Temperature

Experimental study of heat transfer in rarefied gas flow in a circular tube with constant wall temperature

2018 ◽  
Vol 93 ◽  
pp. 326-333 ◽  
Author(s):  
Vadiraj Hemadri ◽  
G.S. Biradar ◽  
Nishant Shah ◽  
Richie Garg ◽  
U.V. Bhandarkar ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Wall Temperature ◽  
Gas Flow ◽  
Rarefied Gas ◽  
Circular Tube ◽  
Rarefied Gas Flow ◽  
Constant Wall Temperature

Second Law Analysis of Laminar Viscous Flow Through a Duct Subjected to Constant Wall Temperature

1998 ◽  
Vol 120 (1) ◽  
pp. 76-83 ◽  
Author(s):  
A. Z. S¸ahin
Keyword(s):  
Viscous Flow ◽  
Entropy Generation ◽  
Wall Temperature ◽  
Viscous Friction ◽  
Inlet Temperature ◽  
Total Heat Flux ◽  
Pumping Power ◽  
Constant Wall Temperature ◽  
Second Law Analysis ◽  
Flow Through

Entropy generation for a fully developed laminar viscous flow in a duct subjected to constant wall temperature is investigated analytically. The temperature dependence on the viscosity is taken into consideration in the analysis. The ratio of the pumping power to the total heat flux decreases considerably and the entropy generation increases along the duct length for viscous fluids. The variation of total exergy loss due to both the entropy generation and the pumping process is studied along the duct length as well as varying the fluid inlet temperature for fixed duct length. For low heat transfer conditions the entropy generation due to viscous friction becomes dominant and the dependence of viscosity with the temperature becomes essentially important to be considered in order to determine the entropy generation accurately.

Second Law Analysis of Fully Developed Convection in a Helical Coiled Tube Under Constant Wall Temperature Using a CFD-ANN Approach

2010 ◽  
Author(s):  
Mostafa Emami ◽  
Mohammad H. Rahimian ◽  
Saeed Alem Varzane Esfehani
Keyword(s):  
Reynolds Number ◽  
Entropy Generation ◽  
Wall Temperature ◽  
Classical Method ◽  
Second Law ◽  
Minor Effect ◽  
Optimization Approach ◽  
Constant Wall Temperature ◽  
Coiled Tube ◽  
Entropy Generation Minimization

The present paper analyses the second law of thermodynamics in a fully developed forced convection in the horizontal helical coiled tube under constant wall temperature. The influence of non-dimensional parameters such as Reynolds number (Re), coil-to-tube ratio (δ) and coil pitch (λ) are inspected on the entropy generation. According to the literature, the coil pitch has a minor effect on the entropy generation compared with Re and δ. Using a CFD tool is a common classical method to find the optimal Reynolds Number and coil-to-tube ratio (δ) based on the entropy generation minimization principal. This approach requires lots of time and resources while the innovative implementation of an Artificial Neural Network (ANN) reduces the simulation time considerably. The data pool generated by the CFD tool is used to train the ANN. As less data is needed to train the ANN in comparison to classical CFD based method, the performance of ANN-CFD optimization approach enhances. As entropy generation minimization principal is applied during the optimization, Nusselt number and friction factor are required to evaluate the entropy generation; these parameters are obtained through a numerical simulation and then are used to train the ANN. The ANN can predict these parameters as a function of different Re numbers and coil-to-tube ratios during optimization. Several different architectures of ANNs were evaluated and parametric studies were performed to optimize network design for the best prediction of the variables. The results obtained from the ANN are compared with the available experimental data to show the network reasonable accuracy.

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