Entropy Generation Minimization Research Articles

Local entropy generation optimization and thermodynamic irreversibility analysis of oval-shaped coaxial ground heat exchangers: A detailed numerical investigation

Optimizing the heat transfer and thermodynamic efficiency of Ground Heat Exchangers (GHE) is crucial for maximizing the energy efficiency of Ground-coupled Heat Pump (GCHP) systems utilized in building heating and cooling applications. This study pioneers an effective approach of both the first and second laws of thermodynamics of the newly oval-shaped coaxial GHEs (oval-CGHEs), assessing heat transfer, thermohydraulic performance, and local entropy generation rate to explore the optimum design and operational conditions for heat exchange maximization and entropy generation minimization. Utilizing a three-dimensional numerical model validated by experimental results, this study examines the trade-offs between heat transfer improvements and entropy generation rate intensification of the oval-CGHEs in comparison to the typical circular-shaped CGHE (circle-CGHE) further than exploring the effect of key operational and design parameters and performing sensitivity analysis. The results reveal that oval-CGHEs exhibit higher irreversibility as a penalty for their superior heat transfer capabilities compared to traditional circular-shaped CGHEs (circle-CGHE), which can be mitigated by optimizing the position of the inner tube. Moreover, the study underscores the criticality of maintaining a balance between enhanced heat transfer and the associated rise in irreversibility, particularly concerning the factors of mass flow rates and installation depths.

Entropy production on mixed convection stagnation point flow of nonlinear radiative fourth-grade hybrid nanofluid through a stretchable Riga surface

The purpose of the current study is to inspect entropy generation, mixed convective stagnation point flow, and thermal transfer features of nonlinear radiative fourth-grade hybrid nanofluid (NF) confined by a convectively heated Riga surface. The heat transport is examined with the existence of two disparate heat source modulations, variable thermal conductivity, and viscous dissipation. The original flow equations are first transmuted using appropriate transformations into non-dimensional ordinary differential equations, which are then solved via an overlapping grid-based spectral collocation scheme. The upshots of various pertinent parameters on velocity, temperature, entropy generation, and valuable engineering quantities are deliberated. Pivotal results obtained reveal that speedily flow of fluid and skin friction can be accelerated by strong magnetic force, rising mixed convection, and material parameters. Also, convective boundary conditions, along with nonlinear radiation and fluctuating thermal conductivity, are recommended for boosting fluid temperature, rates of entropy generation and heat transport. Thermal mechanism in hybrid NF is dominant over simple NF, which implies that performance of hybrid NF is better than that of simple NF. The outcomes of this study can be useful in enriching thermal performance of the working fluid, assisting in diagnosing causes of incompetency in thermal systems, and discovering suitable means of minimizing entropy generation with the intention of mitigating the loss of useful and scarce energy resources.

Thermal lattice Boltzmann approach-based numerical study of nanofluid magnetohydrodynamic forced convection in a back-facing stepped porous channel

Unsteady laminar magnetohydrodynamic forced convection and entropy generation inside a backward-facing step (BFS) porous channel with Cu-H2O nanofluid under a tilted magnetic field is numerically handled using a thermal lattice Boltzmann method (TLBM) with two distribution functions. The Darcy-Brinkman-Forchheimer (DBF) equations filled up with the energy equation (with local thermal equilibrium assumption) have been drawn up as the governing equations model. Their numerical solutions unveiled streamlines, Nusselt number, pumping power, performance index and entropy generation, and impacts of influential parameters (Hartmann number (Ha = 0; 10; 20; 100, 200), Darcy number (Da = 10−3; 10−2; 10−1), magnetic tilt angle (γ = 0, π∕4, π∕2), nanoparticles’ volume fraction (φ = 1 − 4%), medium porosity (ε = 0.6, 0.7, 0.8). The irreversibility analysis is also addressed to highlight the flow behavior. Regarding the validation of the modeling approach deemed, a consensus has been achieved with results available in the literature. Computations revealed that the volume fraction provides a fair performance rating with moderate pumping power. Likewise, the average Nusselt number, the average entropy generation, the pumping power and the performance index have a direct relationship with the Hartmann number, the nanoparticles volume fraction and the magnetic field tilt. Moreover, it can be stated the Cu-H2O nanofluid that seems worthwhile in terms of heat transfer efficiency compared to other examined nanofluids. Entropy generation due to the magnetic field was identified as the main source of irreversibility processes in all cases. Based on the outcomes, it is thought that applying a magnetic field can help minimize entropy generation in practical applications.

Heat transfer augmentation and entropy generation minimization by employing synergistic aspects of hybrid (Fe3O4 + MWNTs) nanoliquid in star shaped enclosure with thermally conductive cylinder and inclined magnetic field aspects

This article aims to simulate optimum thermal convection and minimization in entropy generation in viscous hybrid nanofluid (Fe3O4-MWNTs/H2O) flow in thermally cold star shaped enclosure and containing heated cylinder. Shape effect of cylinder in managing associated hydrothermal attributes is also interrogated. Physical aspect of magnetic field making angle of inclination with domain is accounted. Formulation of transport equations is expressed in the form of dimensionless partial differential setup containing the thermophysical relations of induced hybrid nanoparticles. The constructed flow issue has been simulated by using Galerkin finite element method (G-FEM) with appliance of COMSOL Multiphysics®software computer package.Results and grid convergence assessment tests are also executed in the study. Significant impact of flow controlling parameters on velocity, temperature and entropy generation profiles has been presented in graphical and tabular manner. Variation is three different types of entropies namely, viscous, thermal and magnetic are estimated. Quantities of interest like, total entropy, average Nusselt and Bejan numbers are also calculated against the sundry parameters. Ecological coefficient of performance which measures the efficiency of physical systems is interrogated which is important physical quantity in practical problems. It is inferred from the outcomes that induction of hybrid nanoparticles (Fe3O4 − MWCNT) produces considerable augmentation of thermal attributes of base fluid. Moreover, it is depicted that average Nusselt number exceeds up to 26.5 % for star shaped inner cylinder in comparison to the square cylinder. Increment up to 6 % in average Nusselt number and 2.19 % decrease in entropy is depicted when hybrid nanoparticles are added in the base fluid (ϕ≠0) in comparison to the situation when nanoparticles are not induced (ϕ=0).

Numerical study on entropy minimization in pipes with helical airfoil and CuO nanoparticle integration

Abstract In this study, minimizing entropy generation in a horizontal pipe is numerically investigated through two passive techniques: in the first mode, the helical wire inserts in the pipe were placed at three various ratios of pitch ratio. The second mode is adding cupric oxide nanoparticles at various volume concentrations. Experiments were conducted for Reynolds numbers ranging from 4,000 to 14,000 under a uniform heat flux scenario of 25,000 W/m2. The study utilized the ANSYS 14.5 software, employing the K-omega standard model, which involves three primary governing equations: continuity, momentum, and energy. According to the data, it was determined that the helical wire placed inside the pipe with a small pitch ratio decreased the entropy generation number. Cupric oxide nanoparticles also have a substantial impact on the entropy generation number. The higher volume concentration models had lower entropy generation numbers and Bejan numbers than the other models. Comparative analyses further emphasize the substantial advantages of using cupric oxide nanofluids and helical-wire inserts, with efficiency gains ranging from 5.08 to 11.7%.

Thermodynamic modeling and performance optimization of nanofluid-based photovoltaic/thermal system using central composite design scheme of response surface methodology

This study develops and validates a programming code to demonstrate an iterative resolution analytical thermodynamic modeling method for nanofluid-based photovoltaic/thermal (PV/T) systems. The experimental validation of the model is conducted by constructing and testing a novel PV/T collector that incorporates a flow channel with a double-loop rectangular spiral design. Four different operating independent factors, including solar irradiation (G = 300–900 W/m2), ambient temperature as per climate condition of Jalandhar city of India in July (Ta = 283.15–313.15 K), the CuO-water nanofluid concentration (φ = 0.02–0.08%) and mass flow rate of nanofluid (ṁnf = 201–241 kg/h) are used for thermodynamic performance prediction. Mathematical correlations are developed for each of the dependent response factors, including energetic thermal power output, energetic electrical power output, exergetic thermal power output, and entropy generation. Correlations are based on operating independent factors and their interaction on proposed system performance. Different single and multiple optimization approaches aim to predict optimal dependent and independent factor values. The regression model proposed in this study recommends choosing G = 855.353 W/m2, Ta = 313.148 K, φ = 0.08%, and ṁnf = 201 kg/h in order to optimize the energetic and exergetic electrical and thermal power output while minimizing entropy generation.

Neural network and thermodynamic optimization of magnetized hybrid nanofluid dissipative radiative convective flow with energy activation

This article, motivated by hybrid magnetic coating manufacturing developments, utilizes a neural network-based computational program to study the dynamics of hybrid magnetic nanofluids with entropy generation. A new physico-chemo-mathematical model has been presented to simulate the hybrid magnetic nano-coating flow along a stretching surface to a porous medium with viscous heating. A Rosseland flux model is used for radiation heat transfer and Darcy’s model for the isotropic porous medium. The stretching sheet is porous, and wall suction or injection are possible. A robust neural network has been deployed to optimize the physical parameters controlling the transport characteristics of hybrid nanofluids. Specifically, two hybrid nanoparticle combinations are addressed, namely graphite oxide (GO)-molybdenum disulfide ( Mo S 2 ) and copper (Cu)-silicon dioxide ( Si O 2 ), both with engine oil as the base fluid. The dimensional boundary layer model is transformed via suitable scaling variables from a partial differential system into a dimensionless non-linear coupled ordinary differential system. The transformed boundary value problem is solved numerically with the BVP4C subroutine in the symbolic software MATLAB, which achieves exceptional accuracy. Validation with previous simpler studies is conducted and a good correlation is obtained. The neural network optimization analysis incorporates Bayesian regularization as the training algorithm. The Bejan entropy generation minimization (EGM) analysis shows that with increasing radiation parameter R d , both entropy generation rate and Bejan number are increased. Furthermore, an elevation in Brinkman number Br leads to an upsurge in entropy generation rate and a downtrend in the Bejan number. The numerical solution of the boundary value problem reveals that with an increment in nanoparticle solid volume fraction φ 2 , magnetic parameter M , inverse permeability parameter ϵ , surface injection parameter ( s < 0 ) , Eckert number Ec and radiation parameter R d and with a decrement in suction parameter ( s > 0 ) and Prandtl number Pr , there is a strong enhancement in temperature magnitude and thermal boundary layer thickness. With greater nanoparticle solid volume fraction φ 2 , magnetic parameter M , inverse permeability parameter ϵ , suction parameter s and a reduction in thermal buoyancy parameter λ , strong flow deceleration is induced, and momentum boundary layer thickness is increased. The skin friction coefficient is substantially boosted with lower values of magnetic parameter M , inverse permeability parameter ϵ , suction parameter s and higher values of thermal buoyancy parameter λ . There is a significant decrement also computed in Nusselt number with a greater radiation parameter R d . The simulations provide a good benchmark for future extensions that may consider non-Newtonian behavior.

Numerical analysis of flow and heat transfer characteristics of double-layer heterogeneous single crystal diamond microchannel heat sinks

In order to solve the heat dissipation problems associated with highly integrated and high heat flux microelectronic devices, in this work, a novel type double-layer heterogeneous single crystal diamond microchannel heat sink (DLH-SCD-MCHS) is designed and numerically analyzed, in which the upper channel is rectangular and the lower channel consists of various cavities and rib combinations. The comprehensive performance of the DLH-SCD-MCHS was analyzed by the correlation with pumping power and thermal resistance, and the enhanced heat transfer factor (η). The outcome shows that the DLH-SCD-MCHS significantly enhances the heat transfer while appropriately sacrificing part of the pressure drop. Compared with the traditional double-layer microchannel heat sink (DL-MCHS), the pressure drop of DLH-SCD-MCHS is increased by 23.8–43.5 %, the heat transfer coefficient is enhanced by 74.5–117.1 %, and the η is improved by 62.5–87.4 %. The DLH-SCD-MCHS can reduce the irreversible loss, and the minimum augmentation entropy generation number is 0.64 for the DLH-SCD-MCHS with rectangular cavity and rectangular rib (Model V). As Re = 874, the relative rib width, the relative rib length and the relative position of the ribs of the Model V are 0.5, 0.571 and 0.5, respectively, the maximum η is 1.97. The DLH-SCD-MCHS provides new insights for the management of the heat transfer system of microelectronic devices.

Exergy and entropy analysis of metal foams based on 2nd law of thermodynamics

The available (exergy) and effective use (entropy generation) of energy at the end of thermodynamic processes are significantly important parameters in the design of optimum thermal system. Entropy analysis based on 2nd law of thermodynamics through various pore density metal foams placed in an asymmetrical heated horizontal channel is presented in the current work. Water flows through the channel at different flow rates (inlet velocity varies from 0.02 to 0.3 m/s). Highly porous and different pore density aluminum metal foams such as 10 (0.95), 20 (0.90), 30 (0.92) and 45 (0.90) are inserted into the channel to boost the heat transfer. Darcy Extended Forchheimer (DEF) and local thermal equilibrium (LTE) models are used for the calculation of flow and thermal variables respectively. The numerical outcomes of the examination are first confirmed by comparing with existing experimental literature results. The mean exergy Nusselt number results presented shows that the 10PPI metal foam stretches 35.41 % and 12.20 % higher thermal presentation with respect to 20PPI and 30PPI metal foam. The entropy examination showed that the 20PPI metal foam produces minimum entropy generation at a Reynolds number of 3464.32 and 10PPI metal foam shows highest presentation based on Bejan and entropy generation number.

Computational analysis of entropy generation minimization and heat transfer enhancement in magnetohydrodynamic oscillatory flow of ferrofluids

Improvements in heat transfer rate and entropy generation minimisation are critical issues in many engineering and industrial applications where efficient heat transfer is essential to achieve optimal performance and lower energy consumption. This study investigates the entropy generation of the mixed convection flow of ferrofluids in the presence of viscous and Joule dissipation. The flow is oscillatory and induced by the sinusoidal oscillations of a flat plate in its plane. Two Newtonian fluids, namely, kerosene oil C12H26C15H32 and methanol CH3OH are considered base fluids containing magnetite Fe3O4 nanoparticles. Governing equations are first modelled by employing the fundamental laws of transport phenomena. Then, using scaling analysis, these equations are transformed into a dimensionless system of partial differential equations. Numerical simulations are performed using the Gear-Generalized Differential Quadrature Method (GGDQM), and the model is validated with special cases from the literature. It has been found through numerical analysis that the convergence of GGDQM can be guaranteed by using only a small number of grid points. The thermal boundary layer of methanol-based nanofluid is thicker than that of kerosene. It has been observed that the skin friction coefficient increases for both categories of nanofluids as the values of the Eckert number, solid volume fraction, and Grashof number increase. The Nusselt number increases as the solid volume fraction increases, while the opposite trend is observed when the values of the Hartman, Eckert, and Grashof numbers rise. With increasing values of the Grashof number, the rise in the velocity of methanol-based nanofluids is higher than that of kerosene oil-based nanofluids. The maximum percentage difference between the velocities is identified to be 22.2177% at Gr=4.0. The temperature of methanol-based nanofluids rises more quickly than that of kerosene oil-based nanofluids with increasing values of the Grashof number. It is determined that the largest percentage difference between the temperatures is 20.5968% at Gr=4.0. When Ec=0, the percentage difference between velocities is 29. 1721 %, while the percentage difference between temperatures is 78.7155%. Compared to methanol-based ferrofluid, the volumetric entropy production is more extensive in kerosene-based ferrofluid. On the other hand, in comparison to a kerosene-based nanofluid, thermal irreversibility predominates in a methanol-based nanofluid. The novelty of this study lies in the computational treatment of coupled partial differential equations (momentum and energy) that incorporate buoyancy force, Joule heating and viscous dissipation effects, complementing the underlying physics and mathematical modelling of the research problem.

Computational study of double diffusive MHD natural convection flow of non-Newtonian fluid between concentric cylinders

This study investigated double diffusion natural convection of Casson fluids in an asymmetrical cavity under a constant magnetic field. The intricacies of flow and heat/mass transfer were explored computationally using the finite element method. With applications in fields such as geology, oceanography, metallurgy, and astrophysics, it investigates the impact of key parameters like the Rayleigh number, Casson parameter, buoyancy ratio, Hartmann number, and Darcy number on entropy generation, fluid velocity, and temperature/concentration gradients. The findings illustrate that increasing the Rayleigh number enhances convection and entropy, while a higher Casson parameter leads to reduced mixing due to the fluid's more solid-like behavior. Enhancing the buoyancy ratio improves heat and mass transfer, and a greater Darcy number boosts convection efficiency. Additionally, a higher Hartmann number reduces fluid friction but increases mass diffusion and magnetic disorder, subtly improving thermodynamic efficiency. This research offers valuable insights for optimizing heat transfer and energy efficiency in high-temperature industrial processes, contributing to advancements in sustainability and energy utilization.

Entropy generation analysis of micropolar fluid flow through a vertical microchannel under the combined effect of Joule heating, viscous dissipation, and thermal radiation with convective boundary conditions

ABSTRACT In this era of modern science, microfluidics has gained much importance in the field of research due to large-scale applications in science and engineering. Transfer of heat via nanofluids in microfluidics is the key concept of research. Therefore, here we have considered micropolar fluid for better heat transfer in vertical microchannel and discussed the influences of radiative heat flux, Joule heating, and uniform heat source/sink with viscous dissipation. The equations that govern the physical model are nondimensionalised by the application of suitable dimensionless parameters. Runge–Kutta–Fehlberg 4th−5th order method is applied for solving the non-dimensional governing ordinary differential equations, and precisely computed microrotation, velocity, and temperature profiles of micropolar fluid. The impacts of various factors on entropy generation and Bejan number are explored and analysed through graphs. It is investigated that a higher coupling number decelerates the fluid flow and reduces the temperature of the fluid. Further, minimum entropy generation can be attained by rising coupling number, Hartmann number, and radiation parameter.

Effect of lubricating oil on non-azeotropic refrigerant in flow boiling: an entropy generation analysis

ABSTRACT Entropy generation analysis is a useful method for studying the relationship between heat transfer and pressure drop in flow boiling. The flow boiling process in an actual refrigeration system is inevitably affected by oil. Therefore, the effect of oil on entropy generation needs to be investigated. A new non-azeotropic ternary refrigerant mixture, R447A, was selected as working fluid. Subsequently, flow boiling entropy generation models of R447A with and without oil were established. The effects of individual parameters on entropy generation were investigated. The entropy generation per unit tube length under different conditions was proposed as the benchmark for comparison. The results show that there is an optimal mass flux corresponding to minimum entropy generation per unit tube length at a specific oil concentration, and optimal mass flux decreases with increasing oil concentration. The tube diameter also affects the optimal mass flux of the fluid with oil, which increases with decreasing tube diameter and is smaller than that without oil for the same diameter tube. When the oil concentration is 0–4.95%, the total entropy generation exhibits a decreasing trend. Therefore, within the scope of this research, the addition of oil is beneficial for reducing the entropy generation of heat exchangers.

Entropy optimization and stability analysis in flow of quadratic radiative Ag−MgO/water hybrid micropolar nanofluid over an exponentially contracting permeable Riga surface

ABSTRACT Driven by the significant thermal relevance of low-conductivity electrically active fluids and their impact on controlling flows across multiple industrial and engineering domains, this study aims to thoroughly investigate the primary behavior of electro-magneto-non-Newtonian micropolar A g − M g O / H 2 O hybridized nanofluid, specifically focusing on its flow dynamics and heat transfer characteristics over an exponentially contracting porous Riga surface. The Riga surface, an exceptional electromagnetic sensor surface, holds potential applications in micro-coolers, submarines, and nuclear reactor heat management systems. These findings hold significant relevance due to the prevalent use of micropolar hybridized nanofluids in cooling minute electronic components such as microchips and associated equipment. Our innovative objective is to emphasize the influence of an electromagnetic Riga plate in conjunction with micropolar characteristics, quadratic thermal radiant energy, convective conditions, and velocity slip at the boundary on various key parameters. These parameters include the coefficient of shear stress, coefficient of couple-stress, heat transfer factor (Nusselt number), entropy generation, velocity distribution, micro-rotation or angular velocity, and temperature profiles. We successfully tackled the highly intricate coupled partial differential equations by employing numerical techniques within the MATLAB programming platform. Specifically, we utilized a fourth-order method known as bvp4c to address the challenging boundary value problem. The outcomes revealed the existence of dual solutions characterized by a stable upper solution branch and an unstable lower solution branch within the region of the contracting sheet. Notably, this observation occurred under specific conditions related to the mass suction parameter. The identification of critical values in cases with dual solutions prompted a subsequent stability analysis to discern the nature and characteristics of these solutions. Two distinct solutions have been identified for λ S < λ , reaching termination at λ = λ S within the contracting region. Notably, the first solution yields a positive minimum eigenvalue ( β 1 > 0 ), indicating its stability, while the second solution results in a nonpositive eigenvalue ( β 1 < 0 ), implying instability. Graphical representations illustrate a substantial enhancement in nanofluid temperature for both solution branches, notably influenced by the quadratic thermal radiating parameter, Eckert number, and Biot number. Moreover, the magnetic interaction number and velocity slip parameter notably affect nanofluid motion within the first solution branch. Interestingly, it has been observed that the shear stress and couple stress coefficients exhibit an upward trend with increasing suction value. However, the heat transfer factor (Nusselt number) might decrease in the case of a stable solution. This research direction aims to optimize nanofluid compositions, aiming to minimize entropy generation while maximizing desired thermal properties. Such endeavors are crucial steps towards fostering more efficient and sustainable industrial practices, aligning with the overarching objectives of enhancing energy utilization and promoting industrial growth.

Entropy generation minimization for different types of heat exchangers using nanofluids

ABSTRACT In view of the current global energy situation, increasing the efficiency of heat exchangers can contribute significantly to reducing energy consumption and greenhouse gas emissions. In this study, the effects of nanofluids (SiO2/Water) prepared at different fluid flow rates and different volumetric concentrations (vol.%0.1-0.2-0.3) on three heat exchangers (Shell and Tube, Double Pipe, Plate) with the same capacity were investigated experimentally and statistically. It was concluded that there was an increase of 47% in effectiveness and 87.3% in NTU value with the increase in the volumetric concentrations of nanofluids and fluid flow rate. With the use of nanofluids, it was observed that entropy production decreased by up to 56.08%. The results obtained were analyzed using Response Surface Methodology (RSM) and mathematical models were created and the prediction capabilities of the models were 98% and above. Entropy minimization was performed using statistical methods and it was statistically determined that plate heat exchangers give better results among heat exchangers with the same capacity. It is concluded that the entropy production is minimum when the fluid flow rate is 2 lpm, the volumetric concentration is 0.3% and a plate heat exchanger is used. This study has provided a different and comprehensive perspective on heat exchangers, and it is thought that it will give many ideas to researchers working in this field.

Thermodynamic performance study on the novel efficient flow pattern global construction evaporator

Based on the fluid-efficient flow pattern global construction heat transfer enhancement mechanism, a novel evaporator, called the efficient flow pattern global construction evaporator (EFGE), is presented to improve the in-tube evaporation heat transfer at low quality. The numerical analysis and experimental study of EFGE's thermodynamic performance are performed. Results show that the temperature distribution characteristic of the fluid-efficient heat transfer flow pattern construction is better than that of the initial fluid. The evaporation heat transfer coefficient (HTC) of EFGE is 0.34–1.04 times that of a common parallel flow evaporator (PFE), and the pressure drop of EFGE is only 80%–116 % of that of a common PFE at the quality of 0.9. The theoretical nonuniformity of the evaporation HTC between low- and high-quality flow is approximately 12%–67 %, which is 55%–72 % of the pressure drop. The numerical analysis results agree with the finding that EFGE has better thermodynamic performance than PFE in terms of friction power reduction and minimum entropy generation number.

Minimum entropy generation paths for generalized radiative heat transfer processes with heat leakage

Heat transfer processes (HTPes) with generalized radiative heat transfer law (HTL) [q∝Δ(Tn)] and heat leakage (HL) are optimized. With net amount of heat transferred (NAHT) of working fluid at low-temperature side and given process period, optimal path, that is, optimal temperature configuration of reservoir (TCR), for entropy generation minimization (EGM) of HTP is derived. Universal result for optimal path is provided, and results for four special HTLs, that is, Newtonian, radiative, linear phenomenological, and mixed HTLs, are further provided. Optimal path with EGM is compared with traditional ones of constant heat flux rate (CHFR) and constant reservoir temperature (CRT). Effects of HL and NAHT on optimal results are analyzed. Results show that ratio of heat flux rates between reservoir and working fluid to (n1+1)/2 power of reservoir temperature for EGM of HTPes without HL is a constant, but the optimal relationship between temperatures of working fluid and reservoir with HL is significant different. The differences among TCRs with different heat transfer paths increase with increases of HL and NAHT. The path of CHFR is very close to that of EGM, and the two paths are superior to that of CRT.

ENERGY EFFICIENCY IMPROVEMENT AND ENTROPY GENERATION MINIMIZATION THROUGH STRUCTURAL OPTIMIZATION OF A DOUBLE-LAYER LIQUID-COOLED PLATE WITH CIRCULAR ARC-SHAPED FLOW CHANNELS

Power batteries for new energy vehicles and other high-power electrical devices benefit greatly from liquid-cooled plates for thermal control. In the present work, a liquid-cooled plate with a double-layer arc-channel structure is developed to achieve a uniform temperature distribution on the surface of lithium-ion powered batteries and to reduce operating temperatures. Numerical simulations are employed to examine the flow properties and heat transfer capabilities of the plate. Subsequently, the model is validated experimentally. The structure of the liquid-cooled plate is optimized using a genetic algorithm. In the research, two methods for optimizing the structure of liquid-cooled plates have been proposed based on defining the fitness function of genetic algorithms. The first method uses a dimensionless number to represent the amount of pump power needed to allow the working fluid to absorb one joule of heat energy. The other method uses the entropy generation of the liquid-cooled plate as the fitness function of genetic algorithms. Genetic algorithms may be used to find the minimum dimensionless number and the minimal amount of entropy. The structural characteristics of the liquid-cooled plate may be obtained with the best energy efficiency and the least amount of entropy production using the dimensionless number minimization (DNM) and entropy generation (EGM) optimization techniques, respectively. The performance of the two optimization techniques is contrasted. The maximum temperature of the plate is reduced by 2.58 K and 0.14 K, and the standard deviation of the temperature is reduced by 0.685 K and 0.408 K after the optimization using the creatively established dimensionless number and the entropy generation minimization methods, respectively. The pump work required by the working fluid to absorb one joule of heat energy from the plate is reduced by 70.5&amp;#37; and 12.1&amp;#37;. At two distinct boundary conditions, the proposed liquid-cooled plate outperforms the plates with serpentine and parallel channels in terms of cooling performance or energy efficiency.

Entropy generation and thermodynamic analysis of pool boiling heat transfer on doubly enhanced tubes

To improve the efficiency of the heat exchanger tube, one smooth tube and four doubly enhanced tubes (EX1, EX2, EX3 and EX4) have been investigated for the pool boiling heat transfer experiments in this paper. The indicate that the pool boiling heat transfer coefficient of the doubly enhanced tubes increased visibly with the augmentation of heat flux through the bubble behavior. Heat transfer reinforcement effect of the doubly enhanced tubes are significantly better than that of the smooth tube. Additionally, pool boiling heat transfer coefficient can be further enhanced by raising the saturate temperature. Entropy generation minimization analysis demonstrates that the heat transfer characteristics of like T-shaped tubes (EX1 and EX2) are superior to that of low fin tubes (EX3 and EX4). Particularly, tube EX1 exhibits higher pool boiling heat transfer efficiency. It is observed that a reasonable fin pitch is more advantageous for improving heat transfer characteristics. The utilization of entropy generation minimization analysis provides theoretical support for the design and optimization of doubly enhanced tubes.

Maximizing heat transfer and minimizing entropy generation in concentric cylinders with CuO[sbnd]MgO[sbnd]TiO2 nanoparticles

Heat transfer is crucial because it has industrial uses. A novel type of nanofluids dubbed “ternary nanofluid” is being utilized to boost the ability of conventional fluids to transmit heat since it has a greater heat transfer capacity than solo and hybrid nanofluids. This work investigates the heat transfer capabilities and entropy generation in the cylindrical flow of a ternary nanofluid in the presence of a magnetic field. Minimizing the entropy generation and maximizing the heat transfer of a fluid using ternary nanoparticles (CuOMgOTiO2) is the aim of this work. The finite difference method is used by the MATLAB computer program to solve the problem numerically. The results reveal that the entropy generation minimizes in the presence of CuOMgOTiO2. The heat transfer rate of the fluid increased by 9.9%, 10.8%, and 11.2% on adding TiO2, MgOTiO2, and CuOMgOTiO2 nanoparticles, respectively.