The Entropy Generation analysis of non-Newtonian fluid in rotational flow between two concentric cylinders is examined when the outer cylinder is fixed and the inner cylinder is revolved with a constant angular speed. The viscosity of non-Newtonian fluid is considered at the same time interdependent on temperature and shear rate. The Nahme law and Carreau equation are used to modeling dependence of viscosity on temperature and shear rate, respectively. The viscous dissipation term is adding elaboration to the formerly highly associate set of governing motion and energy equations. The perturbation method has been applied for the highly nonlinear governing equations of base flow and found an approximate solution for narrowed gap limit. The effect of characteristic parameter such as Brinkman number and Deborah number on the Entropy Generation analysis is investigated. The overall Entropy Generation number decays in the radial direction from rotating inner cylinder to stationary outer cylinder. The results show that overall rate of Entropy Generation enhances within flow domain as increasing in Brinkman number. It, however, declines with enhancing Deborah number. The reason for this is very clear, the pseudo plastic fluid between concentric cylinders is heated as Brinkman number increases due to frictional dissipation and it is cooled as Deborah number increases which is due to the elasticity behavior of the fluid. Therefore, to minimize Entropy need to be controlled Brinkman number and Deborah number.

Entropy Generation can be caused by the energy transfer from a high-temperature recourse to a low-temperature resource; this is defined by the second law of thermodynamics. This phenomenon can occur for the Earth by transferring the solar energy from the sun to the earth. The process of Entropy Generation of the Earth is an important concept for the life of the earth. This process also has significant effects on the global hydrological cycle, carbon cycle of the Earth’ s atmosphere, and global warming. This paper presents an approximate method to estimate the Entropy Generation of the earth caused by the sun. Application of the heat engine to calculate the Entropy Generation of the planets has been carried out so far. In this research work, the concept of heat engine is applied to calculate the Entropy Generation of the earth and the atmosphere surrounding it in a relatively simple model. Based upon this calculation, the rate of Entropy Generation of the earth and its surrounding atmosphere is 6. 5149 × 10 14 𝑊 𝐾 ⁄ . Moreover, by considering this imaginative heat engine, the first and second law efficiencies are equal to 0. 11036 % and 0. 11546 %, respectively. The results of this research work have also been justified by similar works on this topic.

The present study addresses the Entropy Generation in the ow of Walters-B nanomaterial. Energy equation consists of ohmic heating, radiation, and heat Generation. Binary chemical reaction with the modi ed Arrhenius energy was employed in this study. In addition, the consequences of thermophoresis, Brownian motion, and viscous dissipation were taken into account. Convergent solutions were presented using homotopy analysis. Intervals of convergence were explicitly identi ed. The results of physical quantities of interest were analyzed. There was a decrease in the mass transfer rate at a higher value of chemical reaction parameter. Enhanced values of Brinkman number and magnetic parameter caused a decrease in the total Entropy rate.

Entropy Generation due to viscous incompressible MHD forced convective dissipative fluid flow through a horizontal channel of finite depth in the existence of an inclined magnetic field and heat source effect has been examined. The governing non-linear partial differential equations for momentum, energy, and Entropy Generation are derived and solved by using the analytical method. In addition, the skin friction coefficient and Nusselt number are calculated numerically and their values are presented through the tables for the upper and the bottom wall of the channel. It was concluded that the total Entropy Generation rate and Bejan number are reduced due to a rise in the inclination angle of the magnetic field. Also, an increment in the heat source props up the fluid temperature and total Entropy Generation rate. This study will help to reduce the energy loss due to reversible process and heat dissipation. The results are also useful for chemical and metallurgy industries.

In the present study, an unlooped pulsating heat pipe has been considered with two liquid slugs and three neighboring vapor plugs. The governing equations including momentum, energy and mass equations are solved explicitly, with the exception of the energy equation of liquid slugs. The aim of the present study is to calculate the Entropy Generation through the performance of a pulsating heat pipe. Additionally, the effects of different pipe diameters and evaporator temperatures have been investigated. Besides, Bejan number has been derived for each case study to investigate the share of heat transfer in Entropy Generation. The results show that by increasing the pipe diameter, the sensible and latent heat transferred into the pulsating heat pipe enhance and the liquid slugs oscillate at high amplitudes. On the other hand, the Entropy Generation value increases as the pipe diameter increases. The evaluated Bejan numbers show that the share of viscous effects in Entropy Generation decreases with increasing pipe diameter. Previous studies have reported that there is a threshold of pulsating heat pipe diameter to operate. However, the results of the present work demonstrate that the use of pulsating heat pipes are not feasible in small diameters. Moreover, the results show that the heat removing performance of pulsating heat pipe improves as the temperature difference of the evaporator and condenser increases. Ourresults demonstrate increments in total Entropy Generation in high evaporator temperatures. Moreover, the Bejan number will increase by any increment in the evaporator temperature and this phenomenon reveals the insignificant role of viscous effects in high evaporator temperatures. To validate the calculations, the results have been compared to those of the previous works. This comparison shows very good agreement.

The present work inspects the Entropy Generation on radiative heat transfer in the flow of variable thermal conductivity optically thin viscous Cu–water nanofluid with an external magnetic field through a parallel isothermal plate channel. Our approach uses the power series from the governing non-linear differential equations for small values of thermal conductivity variation parameter which are then analysed by various generalizations of Hermite- Pade approximation method. The influences of the pertinent flow parameters on velocity, temperature, thermal conductivity criticality conditions and Entropy Generation are discussed quantitatively both numerically and graphically. A stability analysis has been performed for the rate of heat transfer which signifies that the lower solution branch is stable and physically acceptable, whereas the upper solution branch is unstable.

Steady state boundary layer equations over a flat plate with a constant wall temperature can be solved by an integral solution (with three profiles for velocity and temperature), a similarity solution (exact) and a Blasius series solution. The analysis of Entropy Generation for each solution is carried out. The results show that the exact solution (similarity) is the one that minimizes the rate of total Entropy Generation in the boundary layer. Then, the Blasius solution has the least Entropy Generation of all. The bell-shaped profile (sinus profile) in the integral solution generates less Entropy than the piecewise linear profile, consequently. So, with this method, if the exact solution for a specified problem were not available, one could evaluate the approximate solutions and recognize the best one among them. By introducing a new non-dimensional number ($Ej$ number), which is the ratio of thermal Entropy to friction Entropy Generation, one can recognize which of them is dominant in the boundary layer. Also, it is observed that variation of the total Entropy Generation is the same as the variation of boundary layer thickness, so, the non-dimensional total Entropy Generation for various solutions is constant.