Heat Transfer Enhancement Techniques Research Articles

Heat Transfer Performance Analysis of an E-Vehicle Cooling System Using a Hybrid Peltier System

Abstract: This research investigates the heat transfer performance of an electric vehicle (EV) cooling system utilising a hybrid Peltier as integrated system with advancements in EV battery technology, the demand for efficient cooling systems has become crucial for ensuring battery safety, longevity, and overall performance. Present research focus on the application of ethylene glycol as a coolant, exploring the thermal parameters, heat transfer rates, and overall effectiveness of the hybrid cooling system. A literature review highlights the significance of heat transfer enhancement techniques, emphasising the need for energyefficient methods in the automotive industry. The research methodology involves experimental work, analytical calculations, and the preparation of coolant samples to evaluate thermo-physical parameters. The results demonstrate the temperature drop, Overall heat transfer for different flow rates, Logarithmic Mean Temperature difference, and Comparative Power Consumption of different setup. The result showed that presence of ethylene glycol in water enhances the desirable temperature drop of the heat transfer fluid. The Overall heat transfer rate is increased by 58% for EG-100 sample as compared to pure water. Further an ANN model is also developed for prediction of temperature drop, the result showed 2 layer model with 8, 8 neurons as optimum model for prediction.

Design and optimization of a bionic-lotus root inspired shell-and-tube latent heat thermal energy storage unit

Thermal energy storage (TES) is crucial in the efficient utilization and stable supply of renewable energy. This study aims to enhance the performance of shell-and-tube latent heat thermal energy storage (LHTES) units, particularly addressing the issue of the significant melting dead zones at the bottom, which are responsible for the long charging time. This paper proposed a new heat transfer enhancement technique inspired by the air channel distribution inside the root of the lotus. Numerical simulations are used to explore its melting behavior and heat storage performance, and a comparison is made with conventional shell-and-tube TES units. The results indicate that compared to the single-tube type, the bionic-lotus root type reduced the total melting time by 89.1 %, increased the average temperature by 13.2 °C, and enhanced the average effective power density by 7.6 times. Subsequently, multi-objective optimization was conducted based on response surface methodology, and an industrial standard type was constructed according to existing pipeline products to meet the manufacturing standards for mass production. The melting time was further decreased by 5.8 %, and the average effective power density increased by 6.6 %. The results of this study provide a promising and prospective solution for enhancing shell-and-tube LHTES units, with the potential to increase the efficiency, reduce the footprint and manufacturing costs of energy systems equipped with TES.

Influence of Soret–Dufour on a magneto‐micropolar fluid over a porous stretching surface with a nonuniform heat source/sink

AbstractThe goal of the current investigation is to ascertain the influence of Soret and Dufour on a magneto‐micropolar fluid past a permeable stretching surface with a nonuniform heat source/sink. Moreover, the investigation considers the influence of melting heat transfer, as well as the implications of velocity, thermal, and solutal slips. Numerical solutions to the basic governing equations are achieved using the Runge–Kutta–Fehlberg technique. The analysis of our results reveals several important findings. Enhancing the material parameter leads to an upsurge in the velocity profile, whereas the opposite trend exists for the boosting estimations of the magnetic parameter. Enhancing the Soret parameter leads to an improvement in the concentration profile while improving the Dufour factor results in an enhancement in the temperature distribution. These findings are critical for understanding the heat transfer over a stretching sheet, subject to different models and they encompass aspects such as temperature distribution, heat transfer rates, boundary layer characteristics, velocity profiles, and the potential for implementing heat transfer enhancement techniques. The findings of this current investigation are consistent with those that have been previously reported. Fluid dynamics, materials processing, cooling systems, and thermal systems are just a few of the real‐life domains that can benefit from understanding magneto‐micropolar fluid flow over a porous stretching surface with a nonuniform heat source–sink and incorporating Soret and Dufour effects.

An Overview of the Recent Advances in Pool Boiling Enhancement Materials, Structrure, and Devices.

This review attempts to provide a comprehensive assessment of recent methodologies, structures, and devices for pool boiling heat transfer enhancement. Several enhancement approaches relating to the underlying fluid route and the capability to eliminate incipient boiling hysteresis, augment the nucleate boiling heat transfer coefficient, and improve the critical heat flux are assessed. Hence, this study addresses the most relevant issues related to active and passive enhancement techniques and compound enhancement schemes. Passive heat transfer enhancement techniques encompass multiscale surface modification of the heating surface, such as modification with nanoparticles, tunnels, grooves, porous coatings, and enhanced nanostructured surfaces. Also, there are already studies on the employment of a wide range of passive enhancement techniques, like displaced enhancement, swirl flow aids, and bi-thermally conductive surfaces. Moreover, the combined usage of two or more enhancement techniques, commonly known as compound enhancement approaches, is also addressed in this survey. Additionally, the present work highlights the existing scarcity of sufficiently large available databases for a given enhancement methodology regarding the influencing factors derived from the implementation of innovative thermal management systems for temperature-sensitive electronic and power devices, for instance, material, morphology, relative positioning and orientation of the boiling surface, and nucleate boiling heat transfer enhancement pattern and scale. Such scarcity means the available findings are not totally accurate and suitable for the design and implementation of new thermal management systems. The analysis of more than 100 studies in this field shows that all such improvement methodologies aim to enhance the nucleate boiling heat transfer parameters of the critical heat flux and nucleate heat transfer coefficient in pool boiling scenarios. Finally, diverse challenges and prospects for further studies are also pointed out, aimed at developing important in-depth knowledge of the underlying enhancement mechanisms of such techniques.

Hydrothermal performance and entropy production rate of rGO-CO3O4/H2O hybrid nanofluid in corrugated-converging pipes

The ever-growing interest in developing more effective and compact heat exchangers necessitates the investigation of combined passive solutions. Despite the diverse related literature, there are no studies on corrugated-converging pipes. This work examines the effect of Reynold's number (5.0×103≤Re≤5.0×104), diameter ratio (1≤DR≤2), and concentration of nanoparticle (0≤VR≤0.2%), on the Poiseuille number (fRe), average Nusselt number (Nu), performance evaluation criterion (PEC), and EPR of rGO−CO3O4/ H2O hybrid nanofluid (NF) flowing in corrugated-converging pipes of different orientations (inwardly and outwardly) and smooth converging pipes in turbulent flow regime. The k−ω and discrete phase models were used to simulate the turbulent hybrid NF flow by Ansys Fluent. The results revealed that the Nu in the corrugated converging pipe is higher than that of a smooth pipe, but this is accompanied by a higher pressure drop (dP). The argumentation of Nu is attributed to flow acceleration, thinning of the thermal boundary layer (TBL), and an increase in the rate of mixing as a result of the relative increase in turbulence introduced by the presence of corrugation. In addition, it was noted that the modified pipes have lower EPR due to temperature gradient (TEPR) compared with straight pipe. However, the opposite is the case for EPR due to fluid flow (VEPR). The lower TEPR and higher VEPR are attributed to a relative increase in flow turbulence. Quantitatively, the normalized values (referencing smooth pipe) of Nu, (fRe), TEPR, and VEPR at Re=5×103 in inwardly and outwardly corrugated converging pipes and smooth converging pipes of DR = 2 are {2.24, 8.15×101, 4.13×10−1, and 8.62×101}, {1.94, 4.45×101, 4.78×10−1, and 4.15×101} and {1.03, 3.1×101,9.20×10−1, and 3.17×101}, respectively. PEC increases with increasing VR. For instance, across the range of VR considered (0 % ≤ VR ≤ 0.2 %), the values of PEC increase by 20.69 %. Consequently, it can be presented as a promising heat transfer enhancement technique in terms of energy saving. Consequently, corrugated-converging pipes can be presented as a promising heat transfer enhancement technique in terms of energy saving.

Investigation of Heat Transfer Enhancement Techniques on a Scalable Novel Hybrid Thermal Management Strategy for Lithium-Ion Battery Packs

This paper introduces a novel hybrid thermal management strategy, which uses secondary coolants (air and fluid) to extract heat from a phase change material (paraffin), resulting in an increase in the phase change material’s heat extraction capability and the battery module’s overall thermal performance. A novel cold plate design is developed and placed between the rows and columns of the cells. The cold plate contains a single fluid body to improve the thermal performance of the battery module. Experimental studies were conducted to obtain the temperature and heat flux profiles of the battery module. Moreover, a numerical model is developed and validated using the experimental data obtained. The numerical data stayed within ±2% of the experimental data. In addition, the ability of nanoparticles to increase the thermal conductivity of water is examined and it is found that the cooling from the liquid cooling component is not sensitive enough to capture the 0.32 W/m K increase in the thermal conductivity of the fluid. Furthermore, in order to enhance the air cooling, fins were added within the air duct to the cold plate. However, this is not feasible, as the pressure drop through the addition of the fins increased by ~245%, whereas the maximum temperature of the battery module reduced by only 0.6 K. Finally, when scaled up to an entire battery pack at a high discharge rate of 7 C, the numerical results showed that the overall temperature uniformity across the pack was 1.14 K, with a maximum temperature of 302.6 K, which was within the optimal operating temperature and uniformity ranges. Therefore, the developed thermal management strategy eliminates the requirement of a pump and reservoir and can be scaled up or down according to the energy and power requirements.

Investigating heat exchanger tube performance: second law efficiency analysis of a novel combination of two heat transfer enhancement techniques

AbstractIn the study, the focus was on evaluating the second law efficiency of a heat exchanger tube operating under continuous heat flux and turbulent flow conditions. The evaluation involved the use of a hybrid GnP and Fe3O4 and modified coiled wire as passive heat transfer enhancement techniques. The primary objective was to investigate the impact of these combined techniques on thermal and hydraulic performance, entropy generation number, Bejan number and second law efficiency. To achieve this, different mass fractions of GnP and Fe3O4 nanoparticles were used in the hybrid nanofluid, along with two forms of modified coiled wire: barrel type and hourglass type. The experimental results indicated that the utilization of hybrid nanofluids and modified helical inserts led to a noticeable improvement in the second law efficiency of the heat exchanger tube. However, it was observed that the differences in entropy generation number and Bejan number between the barrel and hourglass types were not significant, mainly due to higher frictional losses associated with the latter. The highest recorded second law efficiency was 0.416, while the lowest entropy generation number was 0.118. These values were achieved through the combined use of GnP and Fe3O4 with a mass fraction of 0.4% and a barrel-type coiled wire insert with a pitch ratio of 0.5.

Heat transfer enhancement with tube inserts: How can we define the best benefit?

This study recommends the use of two criteria FG-1a and FG-1b for evaluating the benefits that could be obtained when different heat transfer enhancement techniques are implemented in the heat exchanger design, instead of the most commonly used criterion PEC, based on the constraint of fixed pumping power. When the thermal performances of two heat transfer channels are compared, they must be put under equal conditions, such as fixed heat transfer area, mass flow, and initial temperature. It is also important whether an external thermal resistance of the channel is available or not. The first case is typical for experiments in shell-and-tubes heat exchangers where the objective is an increase in the heat flow, whereas the second case is encountered in experiments with electrical heating of the tube wall, where the objective is a decrease in the driving temperature difference with fixed heat flow. An additional constraint in both cases is the augmentation entropy generation number Nsa ? 1. Through manifold examples, using different twisted tape inserts, we demonstrate how these two criteria have to be implemented for assessing the thermal benefits. The use of the criterion PEC is connected with many erroneous results and misunderstood conclusions that have been revealed in this study.

Heat transfer enhancement techniques using different inserts in absorber tube of parabolic trough solar collector: A review

Heat transfer enhancement techniques using different inserts in absorber tube of parabolic trough solar collector: A review

EXPERIMENTAL AND NUMERICAL STUDY ON EFFECTS OF NEW-GENERATION FINNED HEAT EXCHANGER ON THERMAL PERFORMANCE OF THERMOELECTRIC COOLING SYSTEMS

In this study, an attempt has been made to increase the efficiency of the thermoelectric refrigerator by designinig a new-generation finned heat exchanger. Surface extension, which is one of the most applied passive heat transfer enhancement techniques, was applied for this finned heat exchanger. In this application, the heat absorbed from the cooling room is transferred to the external environment more effectively. In addition, by using an external thermoelectric element (which is installed with the secondary heat exchanger), the heat exchanger cools down faster and the heat is transferred to the environment more quickly. The manufactured cooling system was tested experimentally under different working conditions, including natural and forced convection. The effects of air velocity and applied voltage to the external TE module on thermal performance were examined. Additionally, the external finned heat exchanger has been simulated and heat transfer characteristics have been evaluated using computational fluid dynamics. The lowest and highest COP values have been obtained as 0.003 and 0.011, respectively, when the external TE module has been passive. By providing 12 V for the external TE module, the lowest and highest COP values have been observed as 0.0031 and 0.0042, respectively. In addition, the importance of surface extension applications for the efficient operation of thermoelectric elements has been emphasized.

Investigation of Inlet Air Fogging as a Heat Transfer Enhancement Technique for Gas Turbines

Investigation of Inlet Air Fogging as a Heat Transfer Enhancement Technique for Gas Turbines

Heat transfer in MHD convective stagnation point flow over a stretching surface with thermal radiations

In this study, we have conducted an analysis of steady, incompressible, and magnetohydrodynamic (MHD) Casson fluid flow over a stretching sheet. The primary focus of this research is to investigate the effects of thermal radiation and velocity slip along a stretching sheet. The governing equations for this study are a system of Partial Differential Equations (PDEs) that converted to the Ordinary Differential Equations (ODEs) using similarity transformations. To solve these equations, we have employed the RK–Fehlberg method for solving ordinary differential equations. Governing equations are discretized using the RK–Fehlberg method, and the resulting system of algebraic equations is solved iteratively. These simulations have been conducted under various flow and heat transfer conditions, including variations in the convective number, Prandtl number, and diffusion parameter. The analysis of our results reveals several important findings. Increasing the chemical reaction parameter has been found to reduce the thickness of the concentration boundary layer, while an increase in the Schmidt number leads to an expansion of this boundary layer. These findings are critical for understanding heat transfer in stagnation point flow over a stretching sheet, and they encompass aspects such as temperature distribution, heat transfer rates, boundary layer characteristics, velocity profiles, and the potential for implementing heat transfer enhancement techniques.

Combined passive enhancement techniques improve the thermal performance of latent heat storage system: A design anomaly?

Poor heat transfer rate due to low thermal conductivity of phase change material limits the wide application of latent heat storage (LHS) systems. Thermal performance enhancement techniques can be potential methods to address this major limitation of LHS systems. In this context, the present numerical study examines the individual and cumulative impact of two passive heat transfer enhancement techniques (the orientation of the domain and position of the heat transfer fluid (HTF) tube) on the thermal performance of the latent heat storage (LHS) system consisting of high-temperature (HT) phase change medium (PCM). The individual effect of orientation decreases the charging duration of θ = 0° (horizontal configuration) by 10.5 %, 15 %, and 19.04 % than θ = 30°, θ = 60° and θ = 90° (vertical configuration), respectively. However, the discharging duration remains unchanged for all inclinations (11.5–12 h). The individual effect of eccentricity decreases the charging duration of horizontal (θ = 0⁰, ey = −5 mm,-10 mm,-20 mm) system by 6.25 %,12.8 %, and 18.75 % than concentric horizontal (θ = 0°, ex = ey = 0) system. Moreover, the combined effect of orientation and eccentricity (θ = 0⁰,ey = −5 mm,-10 mm,-20 mm) reduces charging duration by 28.75 %, 33.33 %, and 38.1 % than vertical concentric domain (θ = 90°, ex = ey = 0), respectively. However, eccentricity in vertically upward and downward directions increases the discharging duration compared to the concentric domain. Hence, the combined effect results in a design anomaly for HT-LHS system. The charging and discharging performances are observed to be predominantly sensitive to the Rayleigh number than the Reynolds number.

A review on heat transfer enhancement techniques for PCM based thermal energy storage system

A review on heat transfer enhancement techniques for PCM based thermal energy storage system

Effect of jet angle and jet pitch on the Thermo-Hydraulic performance of solar air heater having absorber plate with jet impingement

This numerical investigation focuses on enhancing the heat transfer characteristics and thermo-hydraulic performance of a solar air heater by employing jet impingement over the absorber plate. The study explores the influence of two geometrical parameters, namely jet pitch ratio (P/Dh) and jet angle ratio (α/90), on the heat transfer, frictional losses, and overall performance of the solar air heater with jet impingement (SAHJI) under various flow conditions, represented by Reynolds numbers (Re) ranging from 3500 to 17500. The simulations are conducted using the RNG k-ɛ model with second-order upwind discretization. A comparative analysis is performed between the SAHJI system and a conventional smooth solar air heater (SPSAH) configuration, revealing a significant enhancement in thermal–hydraulic performance with the use of jet impingement. The investigation identifies the maximum thermo-hydraulic performance parameter, reaching a value of 4.12. This peak performance is achieved at specific values of jet pitch ratio (P/Dh) of 1.30 and jet angle ratio (α/90) of 0.094, respectively, at a Reynolds number of 7500. These findings demonstrate the potential of jet impingement as a heat transfer enhancement technique in solar air heaters, contributing to improved overall system efficiency.

Organic phase change materials melting with electrohydrodynamics (EHD): Numerical simulation and experimental validation

Electrohydrodynamics (EHD), as an active heat transfer enhancement technique, would dynamically manipulate the performance of latent heat thermal storage (LHTS) system. In this paper, the melting characteristics of octadecane with EHD were simultaneously investigated by numerical simulation and experiments. A numerical model based on the finite volume method was developed to solve the Poisson-Nernst-Planck equation, Navier–Stokes equation, and energy equation. The solid-liquid interface position, charge density distribution, velocity field, and liquid fraction were reported. The accuracy of the numerical model was evaluated by the experimental results. For the case of melting without EHD, the numerical results agree well with the experimental results. The relative error between the simulation and experiment is less than 20.0% for the case of melting with EHD. The melting time would be significantly saved with the increasing applied voltage magnitude and inner electrode temperature. The melting time with EHD would be reduced by 13.6 times compared to the natural melting case. The flow in the liquid phase is chaotic and the Coulomb force is dominant than the dielectric force and the buoyancy. In addition, the influence of electrode arrangement on the melting behavior is studied. The melting can be decreased by 1.26 to 1.84 times by adopting four electrodes compared to melting under the configuration of a single electrode with the same cross-section. The proposed numerical model provides a reference for designing and predicting LHTS performance with EHD.

Comparative study of performance enhancement of latent thermal energy storage system with copper porous fin

Phase change material (PCM)-based thermal energy storage (TES) has attained significant attraction towards energy savings and ensures a continuous energy supply. However, the lower thermal conductivity of PCM impedes the efficient transfer in the storage systems, thereby causing longer charging time. Therefore, this paper introduces a novel heat transfer augmentation technique by incorporating copper porous fins in the shell-tube latent heat thermal energy storage. Further, to demonstrate the contribution of porous fins in heat transfer improvement, full-foam, solid-fin and without-fin TES systems are also evaluated and compared. A two-dimensional axisymmetric numerical model is developed and validated with in-house experimental results. It is found that conduction strongly affects the solidification process, exhibiting a greater response rate than the melting process of heat transfer enhancement techniques. Full-foam has higher melting and solidification rates, followed by solid-fin, porous-fin and without-fin. Compared to the without-fin configuration, the temperature response rates of the full-foam, solid-fin and porous-fin are improved by 169.9 %, 44.8 % and 41.88 %, respectively, during the melting process. Moreover, it is revealed that the porosity of foam has a marginally higher impact on the liquid fraction than the pore density. Further, the inclusion of porous-fin and full-foam leads to more uniform temperature distribution in PCM during melting and solidification compared to solid fin and without-fin. Therefore, the porous-fin and full-foam may be utilised for electronic cooling and battery thermal management, which requires uniform cooling at faster rates.

Experimental and numerical investigations on the effect of a novel internal surface micro-grooving toward improving convective heat transfer performance of tube heat exchangers

In the present work, the use of passive heat transfer enhancement technique through surface alteration was explored. The enhancement was achieved through internal conduit surface micro-grooving using a new apparatus that was developed by modifying a magnetic abrasive finishing technique. A new surface profile was created and later verified using optical and laser profiler measurements. The new profile was numerically investigated to compare the heat transfer and hydrodynamic performance against other profiles that have been studied in the literature. It was found from the results that the new profile shows much higher heat transfer improvement and comparable pressure loss to the previously investigated profiles (i.e., square, rectangular, trapezoidal, and circular). Overall, the new groove geometry provides the highest performance followed by the circular, triangular, curvy, square, and rectangular grooves. Also, the results indicate that designs with a smooth profile performs better than those with sharp edges, owing to the elimination of stationary fluid spots within the grooves. The effectiveness between the profiles was compared based on the level of heat transfer enhancement against the flow penalty. Experimental validation was further conducted for the experimentally generated groove. The results revealed that a relatively small surface temperature drop was obtained, corresponding to a slight improvement in heat transfer. This confirms the results generated by the simulation that groove size plays a major role in attaining significant improvement in heat transfer.

Numerical investigation on electrohydrodynamic enhancement of solid–liquid phase change in three-dimensional cavities

As an active heat transfer enhancement technique, electrohydrodynamic has excellent potential to enhance the melting rate during solid–liquid phase change. In this work, the lattice Boltzmann method is adopted to investigate the electrohydrodynamic enhancement of solid–liquid phase change in three-dimensional cavities. The numerical method is firstly validated by several carefully chosen test cases, and then we conducted simulations under different governing parameters and aspect ratios. Results show that the interface morphologies obtained from pure electro-convection and pure thermo-convection are significantly different due to the different directions of the buoyancy and Coulomb forces. Besides, the augmentation of melting due to the electric effect becomes significant when the electric driving parameter T increases. For sufficiently high values of T, the melting performance is mainly dominated by the Coulomb force, and the influence of the thermal Rayleigh number in such a case is insignificant. Further, we note that the melting performance in the enclosure depends on the aspect ratio, and the lateral wall in a three-dimensional cavity with a relatively smaller aspect ratio usually inhibits the electro-convection. Finally, a comparison between the two-dimensional and three-dimensional simulations shows that the added dimension significantly affects the flow dynamics and the interface shape, which cannot be ignored for similar problems.

Numerical Investimation of Heat Transfer in A Rectangular Channel with Triangular Vortex Generators in the Channel at Blade Angle 30° for Reynolds no. of 1500, 2000

Abstract: The compact heat exchanger is widely used in fields such as automobile industry, heating and air conditioning, power system, chemical engineering, electronic chip cooling and aerospace, etc. The subject of heat transfer enhancement is of significant interest in developing compact heat exchanger to meet the desire of high efficiency and low cost with the volume as small as possible and the weight as light as possible. The use of ribs/baffles placing in the cooling channels or channel heat exchangers is one of the commonly used passive heat transfer enhancement technique in single-phase internal flows. Periodically positioned ribs/baffles in the channels interrupt hydrodynamic and thermal boundary layers. Downstream of each rib/baffle the flow separates, recalculates, and impinges on the channel wall and these effects are the main reasons for heat transfer enhancement in such channels. the effect of vortex generators in the spanwise averreged nusselt number. The comparison between the plots of spanwise avereged Nusselt number with and without vortex generators shows that there is a considerable increase in Nusselt number near the vortex generator region and this effect decreases as we move far from the vortex generator region in the stream wise direction.