نتایج جستجو برای: entropy generation

تعداد نتایج: 418190  

Journal: :Entropy 2004
Osamah Haddad Mohamad Abuzaid Mohammad Al-Nimr

The entropy generation due to steady laminar forced convection fluid flow through parallel plates microchannel is investigated numerically. The effect of Knudsen, Reynolds, Prandtl, Eckert numbers and the nondimensional temperature difference on entropy generation within the microchannel is discussed. The fraction of the entropy generation due to heat transfer to the total entropy generation wi...

Journal: :Entropy 2014
Lei Zhang Jinhua Lang Kuan Jiang Songling Wang

Rotating stalls are generally the first instability met in turbomachinery, before surges. This 3D phenomenon is characterized by one or more stalled flow cells which rotate at a fraction of the impeller speed. The goal of the present work is to shed some light on the entropy generation in a centrifugal fan under rotating stall conditions. A numerical simulation of entropy generation is carried ...

Journal: :Entropy 2016
Yonghui Xie Lu Zheng Di Zhang Gongnan Xie

Nanofluid has great potentials in heat transfer enhancement and entropy generation decrease as an effective cooling medium. Effects of Al2O3-water nanofluid flow on entropy generation and heat transfer performance in a rectangular conventional channel are numerically investigated in this study. Four different volume fractions are considered and the boundary condition with a constant heat flux i...

Journal: :Entropy 2013
Richard Farran Nilanjan Chakraborty

A compressible single step chemistry Direct Numerical Simulation (DNS) database of freely propagating premixed flames has been used to analyze different entropy generation mechanisms. The entropy generation due to viscous dissipation within the flames remains negligible in comparison to the other mechanisms of entropy generation. It has been found that the entropy generation increases significa...

2009
Sheng-An Yang

This paper aims to perform the second law analysis of thermodynamics on the laminar film condensation of pure saturated vapor flowing in the direction of gravity on an ellipsoid with variable wall temperature. The analysis provides us understanding how the geometric parameterellipticity and non-isothermal wall temperature variation amplitude “A.” affect entropy generation during film-wise conde...

Journal: :Entropy 2014
Mehdi Safari Fatemeh Hadi Mohammad Reza H. Sheikhi

An overview is presented of the recent developments in the application of large eddy simulation (LES) for prediction and analysis of local entropy generation in turbulent reacting flows. A challenging issue in such LES is subgrid-scale (SGS) modeling of filtered entropy generation terms. An effective closure strategy, recently developed, is based on the filtered density function (FDF) methodolo...

This investigation evaluates the first and second laws of thermodynamics for a flat plate sheet and tube based solar collector located in Abu-Musa Island (in Persian Gulf) in Hormozgan province, Iran where a suspension of molybdenum disulfide (MoS2) nanoparticles with different shapes in water is the working fluid. The main aim of this study is to analyze morphology effects of MoS2 nanoparticle...

2012
John H. Lienhard Gregory P. Thiel

The physical mechanisms of entropy generation in a condenser with high fractions of noncondensable gases are examined using scaling and boundary layer techniques, with the aim of defining a criterion for minimum entropy generation rate that is useful in engineering analyses. This process is particularly relevant in humidification-dehumidification desalination systems, where minimizing entropy g...

Journal: :Entropy 2011
Karan H. Mistry Ronan K. McGovern Gregory P. Thiel Edward K. Summers Syed M. Zubair John H. Lienhard V

Increasing global demand for fresh water is driving the development and implementation of a wide variety of seawater desalination technologies. Entropy generation analysis, and specifically, Second Law efficiency, is an important tool for illustrating the influence of irreversibilities within a system on the required energy input. When defining Second Law efficiency, the useful exergy output of...

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