Irreversibility Rate Research Articles

Entropy analysis of mixed convective electro-magnetohydrodynamic couple-stress hybrid nanofluid flow with variable electrical conductivity in a porous channel

The paper presents a novel study to examine the irreversibility of quadratically mixed convective electro-magnetohydrodynamic (EMHD) flow of a couple-stress hybrid nanofluid (CSHNF) with variable properties in a vertical porous channel. The channel walls are exposed to an applied electric field effect and a uniform transverse magnetic field. The hybrid nanofluid considered is an ethylene glycol (C 2 H 6 O 2) base mixed with multi-walled carbon nanotubes (MWCNT) and silver (Ag) nanoparticles (NPs), assuming the base fluid and nanoparticles to be in a state of thermal equilibrium following the Tiwari-Das nanofluid model. The potential applications of the study can be in microfluidics to nanofluidics, particularly in developing cooling technologies, EMHD pumps, high-end microelectromechanical systems (MEMS), and lab-on-a-chip (LOC) devices used in bioengineering. A constant pressure gradient acting in the flow direction and the buoyancy effect under the quadratic Boussinesq approximation drive the flow. The governing momentum and energy equations are nondimensionalized using pertinent dimensionless parameters and solved by the semi-analytical homotopy analysis method (HAM). The entropy generation and the Bejan numbers are derived to examine the irreversibilities in the system. To investigate the rate of shear stresses and heat transfer, skin friction coefficients and Nusselt numbers on the channel walls are determined. The analysis emphasizes the influence of nanoparticle concentration and electromagnetic field on the flow dynamics, temperature distribution, and system irreversibilities in the presence of porous media. It reveals the enhancement of fluid velocity and temperature degradation for higher concentrations. In contrast, both reduce for higher magnetic and electrical strength. With the enhancement of electrical joule heating and quadratic convection, a higher entropy generation rate is attained with a low rate of heat transfer irreversibility. However, it reduces with higher nanoparticle concentration, electrical strength, porosity, and variable electrical conductivity parameters under the dominance of heat transfer irreversibility.

Chemically reactive non-Newtonian fluid flow through a vertical microchannel with activation energy impacts: A numerical investigation

This work examines the second law analysis of an electrically conducting reactive third-grade fluid flow embedded with the porous medium in a microchannel with the influence of variable thermal conductivity, activation energy, viscous dissipation, joule heating, and radiative heat flux. A suitable non-dimensional variable is included into the governing equations to transform them into an ensemble of equations that are devoid of dimensions. The acquired equations are then tackled using the Runge Kutta Felhberg 4th and 5th order (RKF-45) approach in conjunction with the shooting methodology. Through comparison with the current results, the numerical results are verified, which provides a good agreement. From the present outcomes, it is established that the entropy generation is supreme for the viscous heating constraint, variable thermal conductivity, Frank Kameneski, heat source ratio parameter and third-grade fluid material constraint. The Bejan number boosts up with larger values of activation energy, and Frank Kameneski constraint and the decreasing nature is noticed for increasing third-grade material parameter, viscous heating parameter. With magnetism, the fluid’s velocity slows down because of a resistive force. A similar impact in the channel on velocity is noticed for larger third-grade fluid, activation energy parameter, and Frank-Kameniski parameters and increasing behavior is noticed for variable thermal conductivity, and permeability parameter. Further, it is cleared that the variable thermal conductivity assumption in the channel plate leads to a significant under prediction of the irreversibility rate.

Energy, Exergetic, and Thermoeconomic Analyses of Hydrogen-Fueled 1-kW Proton-Exchange Membrane Fuel Cell.

Exergy analysis evaluates the efficiency of system components by quantifying the rate of entropy generation. In general, the exergy destruction rate or irreversibility rate was directly obtained through the exergy balance equation. However, this method cannot determine the origin of the component's entropy generation rate, which is a very important factor in system design and improvement. In this study, a thorough energy, exergy, and thermoeconomic analysis of a proton-exchange membrane fuel cell (PEMFC) was performed, providing the heat transfer rate, entropy generation rate, and cost loss rate of each component. The irreversibility rate of each component was obtained by the Gouy-Stodola theorem. Detailed and extensive exergy and thermoeconomic analyses of the PEMFC system determined that water cooling units experience the greatest heat transfer among the components in the studied PEMFC system, resulting in the greatest irreversibility and, thus, the greatest monetary flow loss.

Irreversibility of Al2O3-Ag hybrid nanoparticles in mixture base fluid on microchannel with variable viscosity, buoyancy forces, and suction/injection effects: An analytical study

The development of inherent irreversibility in the system is caused by single phase Poiseuille flow considering hybrid nanoparticles (Al2O3-Ag) and mixture fluid (water and ethylene glycol H2O50%-C2H6O250%) in the upright microchannel with unequal viscosity. Taking into account the buoyancy force, suction/injection at the walls, and the form factor and geometry of the nanoparticles. The modeling is based on nonlinear PDEs such as continuity, momentum, and heat equations, which are then transformed to a system of nonlinear ODEs using similarity transformations and solved numerically and analytically. The analytical solution was built using the Differential Transform Method (DTM), and the current results in specific cases are compared to results obtained by the HAM-based Mathematica package, the Runge-Kutta Fehlberg 4th-5th order (RKF45), and those available in literature. The effects of active parameters are investigated on the velocity and temperature, entropy generation and Bejan number. The outcomes of the present analysis reveal that the nanoparticles volume fraction, thermal radiation and Biot number acts to enhance the cooling of the system through the release of thermal energy. in addition, the enhancement in variable viscosity parameter, causes a rise in the irreversibility rate, which in turn boosts the rates of entropy generation and Bejan number. On the other hand, Irreversibility due to heat transfer is dominant in the centerline of the microchannel, while fluid friction irreversibility dominates its walls.

Design and performance analysis of hydro and wind-based power and hydrogen generation system for sustainable development

Renewable energy sources have significance in combating global challenges. In this developed paper, the integration of the hydropower and wind turbine energy conversion system is designed and proposed. The foremost focus of this combined plant is to simultaneously generate clean power, hydrogen, and freshwater through a sustainable way. The developed innovative plant embraced a hydropower plant, wind turbines, a Proton Exchange Membrane unit, and a Reverse osmosis desalination unit. To determine the system performance, detailed thermodynamic performance modeling and sustainability index evaluation are fulfilled on the plant’s indicators. In light of this purpose, several parameters are used to conduct the irreversibility rate, energetic and exergetic efficiency, and other calculations. Along with the examination results, the electricity production rate is calculated as 81591 kW. Moreover, the developed combined system has 61.29 % energetic performance and 57.14 % exergetic performance. The sustainability index value is figured out as 2.33 for the entire system.

CO2 Capture and Enhanced Hydrogen Production Enabled by Low-Temperature Separation of PSA Tail Gas: A Detailed Exergy Analysis

Hydrogen from natural gas reforming can be produced efficiently with a high CO2 capture rate. This can be achieved through oxygen-blown autothermal reforming as the core technology, combined with pressure-swing adsorption for hydrogen purification and refrigeration-based tail gas separation for CO2 capture and recirculation of residual hydrogen, carbon monoxide, and methane. The low-temperature tail gas separation section is presented in detail. The main objective of the paper is to study and quantify the exergy efficiency of this separation process in detail. To achieve this, a detailed exergy analysis is conducted. The irreversibilities in 42 different process components are quantified. In order to provide transparent verification of the consistency of exergy calculations, the total irreversibility rate is calculated by two independent approaches: Through the bottom-up approach, all individual irreversibilities are added to obtain the total irreversibility rate. Through the top-down approach, the total irreversibility rate is calculated solely by the exergy flows crossing the control volume boundaries. The consistency is verified as the comparison of results obtained by the two methods shows a relative deviation of 4·10−7. The exergy efficiency of the CO2 capture process is calculated, based on two different definitions. Both methods give a baseline exergy efficiency of 58.38%, which indicates a high degree of exergy utilisation in the process.

Bioconvection Pumping of Nanofluid Flows in a Curved Conduit with Electromagnetic Fields, Thermal Radiation and Joule Heating

This study analyses the electroosmotic transport of Jeffrey nanofluids containing gyrotactic microorganisms in a two-dimensional curved microchannel enduring peristalsis. In the presence of magnetic field, variable properties, viscous dissipation, Ohmic dissipation, thermal radiation, thermophoresis, and Brownian motion in a wave frame of reference in curvilinear coordinates, the formulation of the problem has been made. The governing equations are solved using Mathematica’s software, yielding numerical solutions. Detailed physical reasoning is used to graphically depict the consequences of the dimensionless variables involved. It has been observed that mobile microorganisms improve both the efficiency of heat transfer and the stability of nanoparticles. It is observed that the irreversibility rate decreases as the viscoelastic parameter, Darcy number, and radiation parameter increase. For small values of the curvature parameter, the nanofluid’s axial velocity is not symmetric about the centerline. Increases in the viscous dissipation parameter, Hartmann number, and Joule heating parameter intensify the temperature distribution, while increases in the radiation parameter have the opposite effect. The nanoparticle concentration decreases as thermophoresis advances and increases as the Brownian motion parameter rises. Electroosmotic phenomenon and magnetic parameter increase the rate of heat and mass transfer along the channel walls.

Two-phase simulation of entropy optimized mixed convection flow of two different shear-thinning nanomaterials in thermal and mass diffusion systems with Lorentz forces

This research compares the momentum, thermal energy, mass diffusion and entropy generation of two shear thinning nanofluids in an angled micro-channel with mixed convection, nonlinear thermal radiation, temperature jump boundary condition and variable thermal conductivity effects. The RKF 45 approach was used to solve the Buongiorno nonlinear governing model. The effect of different parameters on the flow, energy, concentration, and entropy generating fields have been graphically illustrated and explained. The hyperbolic tangent nanoliquid has a better velocity than the Williamson nanofluid. The Williamson nanofluid has higher thermal energy and concentration than the hyperbolic tangent nanoliquid in the microchannel. The Grashof number, both thermal and solutal, increases the fluid flow rate throughout the flow system. The energy of the nanoliquid is reduced by the temperature jump condition, while the energy field of the nanoliquid is enhanced by the improving thermal conductivity value. The nanoliquids concentration rises as the Schmitt number rises. The irreversibility rate of the channel system is maximized by the variable thermal conductivity parameter.

Energetic and exergetic assessment of a ground source heat pump system using low temperature resources in a tropical climate

The energy crisis is a global issue which all nations are involved with it. To this purpose, scientists are developing new energy sources that have less downsides than traditional energy sources. In the current investigation, a ground source cooling system is built in a 234 m2 office building at the gas company bureau in Qom province, Iran, which has a tropical environment. In this climate, which the ground temperature is almost 21 °C, some closed vertical type ground coil with about 170 m depth is constructed for the system, and then some measurements are recorded. The system has been evaluated using the extracteddata and energy and exergy evaluations have been conducted. The outputs show a great sensitivity of the coefficient of performance to the outlet ground coil temperature and the exergy analysis demonstrates that the exergy loss of the ground coil is slightly increased over the workday and the heat pump with exergy dissipation and exergy loss coefficient of 6.4 kW and 0.22 has higher rate of irreversibility compared to other components. Moreover, the average values of Coefficient of Performance (COP) and outlet temperature of ground coil during a workday were obtained as 4.43, 27.43C respectively.

A machine learning approach and numerical investigation for intelligent forecasting of entropy generation rate inside a turbulator-inserted solar collector tube

The irreversibility rate analysis on the solar thermal collectors can be used to determine the regions in the geometry with high intensification of the thermal and viscous entropy generation rates (S˙th and S˙fr), thereby improving the geometry. Although the numerical analysis of the hydrothermal characteristics of the solar thermal collector has been widely studied, the entropy generation rate inside a turbulator insert absorber tube is less understood. In addition, there is still the lack of an accurate predictive model for the estimation of the total entropy generation rate inside the turbulator insert absorber tube. This study deals with the determination of S˙th and S˙fr of water flow inside a tube considering three twisted tape inserts with pitch distances (H) of 50 mm, 100 mm, and 150 mm as well as the Re numbers of 500, 1000, and 1500. The results showed that the escalation of H from 50 mm to 150 mm at Re numbers of 500, 1000, and 1500, S˙fr reduces by 15.40%, 24.50%, and 29.67%, respectively. Also, a 90% increase in S˙fr was observed as Re intensified from 500 to 1500. In addition, the increment in Re from 500 to 1500 reduces by 43%, 41%, and 34% at H values of 50 mm, 100 mm, and 150 mm, respectively. Besides, the increase in H from 50 mm to 150 mm escalates S˙th b by 55%, 63%, and 60%, respectively, for Res of 500, 1000, and 1500. Meanwhile, the entropy generation contour plots revealed that the rate of irreversibilities near the blade and tube wall is high indicating a turbulator geometry modification is needed for the lower entropy generation rates. Moreover, the results of the artificial neural network model showed the high accuracy of the introduced correlation for the estimation of the total entropy generation rate in terms of Re and H.

Entropy production in unsteady MHD double diffusive and chemically reactive nanofluid flow past a rotating permeable plate using overlapping grid spectral collocation technique

The entropy production phenomenon due to the applied external magnetic fields, thermal dissipation, chemical reaction and the impact of rotating pervious plate on heat transfer, nanofluid friction and mass transfer has been numerically explored. The nanofluid flow is presumed to be unsteady, smooth, hydro-dynamically and electrically conducting. The well known Navier–Stokes time-dependent equations in cartesian coordinates for velocity, temperature and concentration are modelled and scaled down to a system of ODEs by applying suitable similarity transformations with unsteady dimensionless parameters. A new numerical scheme known as the overlapping grids spectral collocation method (OGSCM) is applied in finding the approximate solutions to the highly nonlinear ODEs. The results obtained are then used for solving the entropy equation and the rate of irreversibility is represented graphically. Several engineering variables, such as the coefficient of heat transfer, Nusselt number and Sherwood number, are also thoroughly examined. The OGSCM proved to be accurate, computationally efficient, time efficient and converges fast. We discovered that increased applied magnetic field, chemical reaction parameter, rotation parameter, and Schmidt parameter insert more energy into the system which reduces the thermal boundary layer and hence reducing the rate of entropy generation. Furthermore, the entropy generation rate is increased by increasing the Grashof number, Brinkman number, permeability, Prandtl number, and thermal radiation parameter.

Investigation of entropy generation and thermohydraulic characteristics of Al2O3–CuO hybrid nanofluid flow in a pipe at different inlet fluid temperatures

This work investigates the thermohydraulic behavior and the rate of thermodynamic irreversibility of water-based Al2O3 and Al2O3 + CuO hybrid nanofluid (HNF) in a circular copper tube subjected to a constant heat flux (CHF) of 8625 W/m2. The fluids under discussion flow in a tube at inlet fluid temperatures of 30, 45, and 60 °C. The thermophysical characteristics of the Al2O3 and HNF were studied at various temperatures and concentrations. The Nusselt number (Nu), entropy generation number (EGN), and friction factor were determined for the HNF (0–1 vol%) at different ranges of Reynolds numbers (Re) from 7000 to 44,662. The outcome of the HNF for 1 vol% is compared with that of Al2O3 nanofluid (NF). The findings show that the maximum amplification of Nu is 51, 59, and 79.7% observed for 1 vol% of HNF compared to water at 30, 45, and 60 °C. The pressure drop (Δp) and exergy efficiency (ηexe) of HNF increases with concentration and Re. The friction factor of HNF rises with concentration; however, it reduces at higher Re. Total entropy generation (TEG) of HNF reduces at higher Re and concentration. The thermal performance factor (TPF) of HNF is determined at various inlet fluid temperatures. The highest and lowest TPF of 1.7 and 1.02 were found for 1 and 0.1 vol% of HNF at 60 and 30 °C, respectively. The novel regression equations were developed to estimate the Nu, TEG and friction factor of HNF. Overall, Al2O3 + CuO HNFs can be employed as an alternative fluids thermal system cooling.

Minimization of exergy destruction with discrete metal foam filling in a pipe under turbulent flow condition

PurposeThis study aims to present the numerical analysis of exergy transfer and irreversibility through the discrete filling of high-porosity aluminum metal foams inside the horizontal pipe.Design/methodology/approachIn this study, the heater is embedded on the pipe’s circumference and is assigned with known heat input. To enhance the heat transfer, metal foam of 10 pores per inch with porosity 0.95 is filled into the pipe. In filling, two kinds of arrangements are made, in the first arrangement, the metal foam is filled adjacent to the inner wall of the pipe [Model (1)–(3)], and in the second arrangement, the foam is located at the center of the pipe [Models (4)–(6)]. So, six different models are examined in this research for a fluid velocity ranging from 0.7 to7 m/s under turbulent flow conditions. Darcy Extended Forchheimer is combined with local thermal non-equilibrium models for forecasting the flow and heat transfer features via metal foams.FindingsThe numerical methodology implemented in this study is confirmed by comparing the outcomes with the experimental outcomes accessible in the literature and found a fairly good agreement between them. The application of the second law of thermodynamics via metal foams is the novelty of current investigation. The evaluation of thermodynamic performance includes the parameters such as mean exergy-based Nusselt number (Nue), rate of irreversibility, irreversibility distribution ratio (IDR), merit function (MF) and non-dimensional exergy destruction (I*). In all the phases, Models (1)–(3) exhibit better performance than Models (4)–(6).Practical implicationsThe present study helps to enhance the heat transfer performance with the introduction of metal foams and reveals the importance of available energy (exergy) in the system which helps in arriving at optimum design criteria for the thermal system.Originality/valueThe uniqueness of this study is to analyze the impact of discrete metal foam filling on exergy and irreversibility in a pipe under turbulent flow conditions.

Advance exergy and coefficient of structural bond analysis of dedicated mechanical subcooled vapor compression refrigeration system

The dedicated mechanical subcooled (DMS) refrigeration system is examined in the current study, based on the configuration of energy and exergy. The performance of a simple vapor compression refrigeration system (VCRS) and dedicated mechanical subcooled system are evaluated while maintaining the same cooling capacity (i.e. 100 kW). The results of comparative study showed an improvement of 8.2% in the coefficient of performance (COP) of the DMS system. Additionally, it has been discovered that the exergetic efficacy of the VCRS and DMS systems is 32.8% and 35.2%, respectively. The above results proved that, the suggested system perform better with more efficient cooling technology, which proves it to be a better option for design engineers in water chilling application in the foreseeable future.The coefficient of structural bond (CSB) and advanced exergy analysis (AEA) methodologies along with environmental benefits of the DMS system are also looked into in light. The value of CSB for conderser-1 is observed to be highest (2.08), with total irreversibility rate of 22.7%. However, in case of compressor-1 the highest irreversibility rate of 34.8% is observed but its CSB value is only 1.09. Therefore, by enhancing the performance of system components, it is possible to avoid 42.9% of the overall irreversibility rate of the dedicated mechanical subcooled system using enhanced exergy analysis.

Design and evaluation of a novel plan for thermochemical cycles and PEM fuel cells to produce hydrogen and power: Application of environmental perspective

In the present article, a green and efficient multi-generation system equipped with proton exchange membrane (PEM) fuel cells as the main mover is presented and thoroughly examined. The proposed novel approach dramatically reduces the amount of carbon dioxide produced by using biomass as the primary energy source for PEM fuel cells. The waste heat recovery method is offered as a passive energy enhancement strategy for efficient and cost-effective output production. It uses the extra heat generated by the PEM fuel cells to produce cooling through the chillers. In addition, the thermochemical cycle is included to recover the waste heat from syngas exhaust gases and produce hydrogen, which will significantly help the process of going green transition. The suggested system's effectiveness, affordability, and environmental friendliness are assessed via a developed engineering equation solver program code. Additionally, the parametric analysis assesses the impact of major operational factors on the model's performance from thermodynamic, exergo-economic, and exergo-environmental indicators. According to the results, the suggested efficient integration achieves an acceptable total cost rate and environmental impact while obtaining high energy and exergy efficiencies. The results further reveal that the biomass moisture content is significant since it highly impacts the system's indicators from various aspects. From the conflictive changes between the exergy efficiency and exergo-environmental metrics, it can be concluded that choosing a proper design condition satisfying more than one aspect is highly important. According to the Sankey diagram, the worst equipment from the energy conversion quality is gasifier and fuel cells, with the highest irreversibility rate of 8 kW and 6.3 kW, respectively.

An innovative biomass-driven multi-generation system equipped with PEM fuel cells/VCl cycle: Throughout assessment and optimal design via particle swarm algorithm

This work proposes a new, efficient, economically, and environmentally viable approach for developing cutting-edge energy systems and assisting the anticipated global green transition with maximal renewable integration. The cogeneration of hydrogen and power is driven by biomass, which in turn drives the vanadium chloride cycle and the proton exchange membrane fuel cells. A cooling absorption unit is powered by waste heat recovered using a passive energy improvement technique to improve performance and cut costs. Energy, exergy, exergo-economic, exergo-environmental impacts, and CO2 emission rate of the suggested renewable-based model are analyzed using an engineering equation solver tool. Parametric analysis is also used to assess the impact of key operational factors on main performance indicators. With machine learning, a particle swarm method is implemented in MATLAB to find the optimal operating state with high precision and low computing cost. The results show the importance of multi-objective optimization by pointing out a conflicting change in the performance metrics from different angles by picking up the biomass moisture content and fuel cell current density. According to the optimization results, an acceptable total cost, environmental damage effectiveness, and exergy efficiency of 5 $/h, 0.86, and 55% are achieved through the integration of particle swarm optimizer and artificial neural network method. The results further reveal that the gasification temperature is not sensitive; however, changing the fuel cell utilization factor significantly impacts the system's performance from all sides. Finally, the chord diagram of the irreversibility rate indicates that the fuel cell and gasifier have the highest destruction of 6.4 kW and 2.6 kW under the optimum condition, owing to mixing and chemical reactions. As for the environmental aspect, by optimizing the system, the system's CO2 emission are greatly reduced.

Electrothermal analysis for reactive Powell Eyring nanofluid flow regulated by peristaltic pumping with mass transfer

The proposed work presents an optimized thermal frame for electroosmosis optimized peristaltic transportation of reactive Powell-Eyring magneto-nanofluid with mass transfer. The peristaltic phenomenon with the applications of electro-kinetic pumping develops the effectiveness of smart pumps in nanotechnologies and medical uses. The thermal and mass characteristics of a nanofluid is obtained by evaluating the well-known Buongiorno model, which allows us to identify appealing aspects of thermophoretic diffusion and Brownian motion. The non-Newtonian nanofluid flows through a porous space under the influence of variable thermal conductivity, chemical reactions, magnetic field, and mixed convection. Zero mass flux at the channel borders are taken. A biological estimate of the creeping transportation model, long wavelength assumptions, and Debye-Hückel linearization is revealed. The resulting equations are then resolved numerically, and the results obtained are discussed in detail along with their graphical representation. The investigation reports that electroosmotic and Joule heating parameters significantly improve the temperature of Powell Eyring nanofluid. The total entropy (irreversibility rate) of the system can be controlled with the thermal conductivity parameter in the case of auxiliary pumping. A development in concentration profile is seen for greater chemical reaction parameters. Further, nanofluid flow declines with higher values of electroosmotic velocity and the Powell-Eyring fluid parameter.

Non-Darcy nanoliquid buoyant flow and entropy generation analysis in an inclined porous annulus: Effect of source-sink arrangement

In several engineering and industrial applications, the primary challenge in the design of thermal devices is to minimize the entropy production with maximum energy dissipation so that the system efficiency could be enhanced. In particular, an inclined partially heated annulus is far challenging due to the presence of both tangential and normal gravity components, which produces major impacts on the fluid movement and associated transport rates as well as entropy production. From several important applications point of view, the current investigation is mainly focused to address the combined impacts of source-sink arrangements as well as the annular inclination on buoyant nanoliquid motion, thermal dissipation along with irreversibility distribution in a tilted porous annulus. The governing model equations are numerically solved by utilizing the finite difference based time-splitting and relaxation techniques. Using second-order finite difference approximation, the partial derivatives are approximated and the resulting system of algebraic equations are inverted using Thomas algorithm. The influence of various controlling parameters such as geometric inclination angle, nanoparticle shape, Darcy number, length and position of source-sink on fluid movement, thermal and entropy distribution are scrutinized in detail. Through a wide range of numerical experiments, it has been found that the annular inclination angle and location of source-sink arrangement plays a vital role on fluidity and flow patterns of nanoliquid in the porous saturated annulus. For smaller size of source-sink pair, higher thermal dissipation with minimal entropy production could be achieved, which is an important observation for the design of thermally efficient systems. We have also noticed that a better thermal transport rate with minimum irreversibility rate could be attained for a particular source-sink arrangement, in particular for γ=0∘, the staggered positioning of source-sink pair is beneficial rather than in-line arrangement. Among the various parameters arising in this analysis, the nanoparticle shape has been one of the key parameters to test the thermal efficiency. It has been predicted that the blade shaped nanoparticle induces better thermal efficiency, among the five different shapes of nanoparticle. The outcomes of this analysis could be utilized in applications, such as solar systems, electronic equipment cooling and heat exchangers.

Exergetic and exergoeconomic implications of a recuperative organic Rankine cycle plant for power production from an abandoned oil well

This study was aimed at assessing the exergetic and exergoeconomic implications of adopting a recuperative (SUB-REGEN) instead of a non-recuperative (SUB) organic Rankine cycle (ORC) plant for power production from an abandoned oil well. The geometric parameters of a typical oil well in Nigeria were adopted for simulating the heat source. The specific exergy costing (SPECO) approach was employed for the exergoeconomic assessment. Results showed that for the SUB ORC, the evaporator had the highest exergetic efficiency of about 86% and the condenser the highest cost rate of exergy destruction of about 47%. For the SUB-REGEN ORC, the condenser had the highest contribution ratio of 0.41 to the total irreversibility with a cost rate of about 19.1 k$/h. Overall, the integration of a recuperator would increase the ORC exergetic efficiency from around 55% to 58%, albeit with a consequent increase in the cost rate of system irreversibility by about 24%.

Flow and thermal analysis of Oldroyd 8 constant fluid in a porous channel

AbstractThe present research is based on the thermal and flow properties of the viscoelastic Oldroyd 8 constant fluid in an upright microchannel. The energy and momentum equations were solved with the support of temperature Jump and velocity slip boundary conditions. To measure the irreversibility rate of the flow system, the acquired results of velocity and thermal equations were used. To crack the current mathematical model problem, the numerical Runge–Kutta–Fehlberg method was used. With the aid of graphs, the effect of physical parameters such as thermal radiation, thermal‐dependent heat source, Joule heating, fluid parameters, velocity slip, and temperature Jump parameters on the fluid flow, thermal energy, and system entropy generation was discussed. Fluid parameters have different effects on the velocity profile. The Grashof and Hartmann numbers demonstrate opposite effects on the momentum field. The thermal energy of the system reduces with thermal radiation and temperature Jump factor. The thermal radiation, Hartmann number, and temperature Jump parameters reduce the system's irreversibility rate. With the Brinkman number and temperature Jump parameter, the irreversibility ratio increases.