Straight Fins Research Articles

Experimental investigation of an alternative battery pack thermal management system

Placing the batteries in PCM (Phase Change Material) filled containers causes a thermal imbalance in the pack because the heat can be dissipated from the sides, but it is accumulated in the center. An alternative geometry is proposed and tested to solve this problem. The thermal performance of the proposed battery pack structure employing PCM has been experimentally studied in free convection conditions. The battery pack is formed by placing 12 test batteries in the same size of 26650 LiFePO4 in custom-designed aluminum (Al 6065) chamber. The single-piece chamber consists of three subchambers connected by straight, rectangular, and parallel fins. The cells are positioned in the 4S3P arrangement. Three different PCMs with different melting temperatures are utilized, and their effect on the battery pack temperature is sought under a stagnant air environment (21 °C). The pack has been tested during discharging at 2C (1.3 W), 3C (2.75 W), and 5C (7.83 W). The heat generation values are adopted from the literature. The maximum temperature in the cells and the maximum temperature deviation between the cells are monitored while the cells are being charged or discharged for different test procedures. Instead of placing PCM and cells in a single case like in studies in the literature, a tailor-made finned geometry helped provide a more homogenous temperature in the cells thanks to the finned structure on the air side. In this way, the maximum temperature difference inside the battery pack is kept below 5 °C for all cases except the extreme case of cyclic 5C discharge/charge analysis with CrodaTherm47. The maximum temperature of the battery pack could be kept below the critical value (60 °C) only when CrodaTherm37 was employed for three consecutive cycles at a discharge rate of 5C/7.83 W as the fin temperatures could be kept at the optimum level, and the PCMs latent heat can be exploited the most.

Passive thermal control of a triple-junction solar cell at high concentrations using various finned heat sink configurations

Designing an effective heat sink that is light, inexpensive, and simple to manufacture and install, is crucial in developing a heat control strategy for high concentrated triple-junction (TJ) solar cells to maintain the cell operating temperature below the maximum allowed limit. Such heat sinks ensure better electrical output power and efficiency at a cheaper cost. Thus, the present research focuses on the passive thermal regulation of a triple-junction solar cell utilizing four different finned heat sink configurations; (A) flat plate, (B) straight fins, (C) pin fins, and (D) flared fins heat sink. A comprehensive 3D thermal and electrical model is developed and computationally simulated, incorporating the cell module layers coupled with the aluminium heat sink. The performance of the proposed system with different heat sink designs is investigated at various concentration ratios (CR) of the solar irradiance ranging from 50 suns to 1250 suns, air temperatures ranging from 25 °C to 40 °C, and wind speeds ranging from 1 m/s to 5 m/s. In hot climatic conditions (40 °C and 1 m/s), the integration of the proposed heat sink configurations A, B, C, and D enables the cell to operate safely (below 110 °C) at high concentration ratios of 440 suns, 1435 suns, 1250 suns, and 1775 suns, respectively, and produce large electric power of 15.2 W/cm2, 49.7 W/cm2, 43.3 W/cm2, and 61.4 W/cm2. In contrast, the maximum permissible concentration ratio of an uncooled cell operating in the same conditions is limited to 77 suns with an electrical output of 2.7 W/cm2. Although the flared fins heat sink is the heaviest, weighing about 0.6 kg, and the flat plate one is the lightest with 0.05 kg, the environmental analysis revealed that utilizing the former for cooling concentrated photovoltaic systems could reduce annual CO2 emissions by 1475.2 tons/m2 compared to 364.5 tons/m2 for the latter if both are operated at the maximum permissible solar concentration ratio.

A radiating straight fin with constant thermal properties by modified perturbation method

A radiating straight fin with constant thermal properties by modified perturbation method

Energy storage performance improvement of phase change materials-based triplex-tube heat exchanger (TTHX) using liquid–solid interface-informed fin configurations

The future of power generation is predicted to be greener with greater uptake in renewable energy which will be more intermittent and make matching demand harder. Latent thermal energy storage using phase change materials (PCMs) could provide a solution to that problem. PCMs can store large amounts of energy in small volumes, however, the main issue is the low conductivity of PCMs, which limits the rate that energy can be stored due to the slow melting and solidification processes. In the present study, we design and optimise a flow structure-informed fin configuration for triplex-tube heat exchangers (TTHXs) that accelerates the PCM melting process to allow for faster energy storage rates. The computational fluid dynamics modelling is developed to evaluate different TTHX geometries and find the most efficient fin geometries. The results show that an optimal fin geometry can provide a 57.4 % reduction in melting time, which demonstrates that fins offer a very effective way of reducing the melting times of PCMs without taking up much volume. We also found that fins in the lower half of the PCM are more effective in reducing total melt time than fins in the upper half. It is revealed that curved fins offer better performance when compared to similar straight fins. Lastly, it is observed that horizontal or angled surfaces allow for more natural convection in TTHX. The findings can be used to inform future studies on energy storage performance improvement of PCMs.

Studying the advantages of equal curvature curved fin to enhance phase change heat storage

Strengthening the heat storage process is the most important means for its application of the phase change heat storage system. By adding fins to the phase change material, the heat transfer area can be expanded and consequently effectively accelerates the heat storage rate. Therefore, this paper proposed a new fin optimization method: the combination of fins of different structures under non-uniform arrangement conditions. This study proposed an equal-curvature curved fin structure based on straight fin. Then, under the same amounts of fins and heat transfer area, the heat storage system with curved fin and straight fin were studied and analyzed. Moreover, by comparing with straight fin, the effect of the combined curved and straight fins on the performance of heat storage system with different arrangements was exhibited and discussed. The results indicated that curved fins have the effect of enhancing heat transfer by comparing with a straight fin. However, the combined curved fin and straight fin with uniform arrangement has no obvious advantage over straight fin model. Compared with the uniform arrangement, under the condition of non-uniform arrangement, the melting performance of the curved fin and straight fin combination models was improved by 24.5 % at most and at least 9.2 %, the melting performance of the straight fin model is improved by 7.7 %. Finally, the results of the optimization method proposed by other scholars are compared to prove that the optimization method proposed in this study is feasible. This work provides the new ideas for fins design with different structures and non-uniform arrangement of heat storage system.

Performance prediction of a fin–metal foam–cold thermal energy storage device: Solidification

Latent heat storage technology is a valuable research direction to alleviate the imbalance of energy supply and demand, but its application is limited by the low thermal conductivity of phase change material. In recent years, the fin–foam structure is proven to alleviate this problem. The solidification behavior of the phase change material in this structure should be predicted to promote its engineering application. In this study, a cold thermal energy storage unit with metal foam and straight fins was constructed. On the basis of dimensionless analysis, experimental and numerical methods were used to investigate the structural parameters of straight fin and metal foam on the liquid fraction and effective Nusselt number (Nu*). Results showed that the height and spacing of fin are the main factors affecting the solidification rate of phase change material, compared with the porosity, pore density and material of metal foam. When fin height increases from 17 to 57 mm and spacing reduces from 120 to 3 mm, the Nu* of the phase change material increases by 1.5 and 12.61 times, respectively. The transient correlation between liquid fraction and Nu* of phase change materials is obtained to guide related design.

High power density thermal management of discrete semiconductor packages enabled by additively manufactured hybrid polymer-metal coolers

Discrete-packaged wide bandgap (WBG) semiconductor devices provide a flexible and cost-effective solution for scalable highly dense power electronics. However, their utilization at high power levels is limited due to various challenges, while the effective thermal management if one of them. We develop a liquid cooled thermal management solution for discrete semiconductor packages using polymer-metal hybrid cooling structure design and integration. Coolant flowing through an additively manufactured polymer manifold is guided to finned metal heat sinks having low thermal resistance and overall mass. Here, we study a number of prototypes designed for integration of silicon carbide (SiC) MOSFETs in TO-247 package. The cooling integration is benchmarked with a baseline design having an aluminum heat sink with square inline pin fins. The cooling strategy is tested experimentally with results used to validate a finite element numerical approach. Fin design parameters including fin height, thickness, spacing, and arrangement are studied to assess their impact on heat sink temperature and pressure drop. Zigzag fins showed the most promising performance when compared to straight fins, inline fins, and staggered pin fins. The zigzag design showed lower maximum temperatures at comparable pressure drop with the baseline design. The impact of thermophysical properties of the cooling fluid (water, ethylene glycol, and Novec 7300), heat sink (copper and aluminum), and electrical isolation (gap pad, aluminum nitride) are also reported. The optimal design employing zigzag fins with a copper heat sink and an aluminum nitride heat spreader achieved 32.5 % improvement in thermal performance over the baseline design with a modest 60 % increase in pressure drop and 68 % higher mass. The optimized design enables a maximum heat rejection capability of 225 W per single MOSFET package, an equivalent to 75 W/cm2 heat flux dissipation using single phase cooling.

One Dimensional Steady-State Heat Transfer on a Star Fin Shape

The convection heat transfers on a surface exposed to the fluid may be enhanced by attaching to the surface, known as the fins. To keep the system stable, heat transmission via solids, boundaries, or walls must be continuously dissipated to the environment or surroundings. A large quantity of heat must be dissipated from a small space in many engineering applications. A fin can boost the surface area’s effectiveness; hence, maximize convectional heat. Two shapes of straight aluminum fins have been used, cylindrical and star shape. The result shows that the star fins are appealing due to the same diameter and length; it has a lot more heat transfer than a cylindrical fin. In electronic devices, cylindrical and star fins are provided on the surface of the processor device. The result is done by SolidWorks simulation with 300 ºC on the surface as well as cylindrical and star fin. Input parameters like thermal conductivity, heat transfer coefficient, as well as fin’s density and dimensions are measured. The temperature distribution, heat flow, as well as heat flux all resembles output parameters.

Machine Learning-Based Approach for Modeling the Nanofluid Flow in a Solar Thermal Panel in the Presence of Phase Change Materials

Considering the importance of environmental protection and renewable energy resources, particularly solar energy, the present study investigates the temperature control of a solar panel using a nanofluid (NFD) flow with eco-friendly nanoparticles (NPs) and a phase change material (PCM). The PCM was used under the solar panel, and the NFD flowed through pipes within the PCM. A number of straight fins (three fins) were exploited on the pipes, and the output flow temperature, heat transfer (HTR) coefficient, and melted PCM volume fraction were measured for different pipe diameters (D_Pipe) from 4 mm to 8 mm at various time points (from 0 to 100 min). Additionally, with the use of artificial intelligence and machine learning, the best conditions for obtaining the lowest panel temperature and the highest output NFD temperature at the lowest pressure drop have been determined. While the porosity approach was used to model the PCM melt front, a two-phase mixture was used to simulate NFD flow. It was discovered that the solar panel temperature and output temperature both increased considerably between t = 0 and t = 10 min before beginning to rise at varying rates, depending on the D_Pipe. The HTR coefficient increased over time, showing similar behavior to the panel temperature. The entire PCM melted within a short time for D_Pipes of 4 and 6 mm, while a large fraction of the PCM remained un-melted for a long time for a D_Pipe of 8 mm. An increase in D_Pipe, particularly from 4 to 6 mm, reduced the maximum and average panel temperatures, leading to a lower output flow temperature. Furthermore, the increased D_Pipe reduced the HTR coefficient, with the PCM remaining un-melted for a longer time under the panel.

Thermal control of temperature-sensitive electronic components using a vapor chamber integrated with a straight fins heat sink: An experimental investigation

Cooling temperature-sensitive appliances, such as electronic components, has recently become essential in their design and development to reduce the negative effect of excessive temperature rise on performance. The current experiment focuses on passive cooling of electronic devices utilizing an innovative vapor chamber with a cylindrical cross-section that is integrated with a straight fins heat sink. Therefore, a fabricated system is attached to an electric heater to imitate the heat dissipation from electronic devices. Several experiments are conducted to investigate the effect of two working fluids (Ethyl alcohol and water), seven varied charge ratios (ranging from 20% to 65%), different system orientations (ranging from 0° to 180° in 45° intervals), and seven distinct heat load values on overall system performance. The performance of the integrated vapor chamber-straight fins (VC-SF) heat sink is then compared to those of two conventional heat sinks, a straight fins (SF) heat sink and a solid copper plate (SCP) heat sink. The results reveal that using the integrated vapor chamber-straight fins (VC-SF) heat sink significantly reduces the average front wall temperature associated with the electronic component when compared to other heat sinks, and this effect holds true throughout all operating scenarios. Furthermore, when compared to other working fluids and charging ratios, the system filled with pure water as the working fluid and a charge ratio of 25% performs better for all operating conditions. Finally, at an inclination angle of 0°, the minimal hot wall temperature associated with the electronic component's operating temperature can be reached, resulting in the greatest performance. In contrast, the highest hot wall temperature is attained at an inclination angle of 180°, regardless of the applied heat load or charging ratio.

Numerical investigation on cooling performance of oil cooled PMSM jacket design with vertical straight fin design

Cooling has been an important parameter to extend the high-speed generator operating conditions. Literature highlights the high speed generator jacketjacket of generator is a crucial part that need to be cooled down to dissipate the coil temperature to ensure the performance of the Permanent magnet synchronous machine (PMSM). Research shows there are work done on the internal jacket design to improve cooling. This research work focuses on further enhancement of more design parameters for the internal oil flow jacket space design to dissipate heat better. The vertical straight fin configurations were deployed to investigate the effect of heat transfer with same cooling medium, Oil. The numerical analysis using ANSYS-FLUENT was completed, converged and mesh independent results were presented. The vertical straight fins improve heat transfer more than triple as compared to the baseline. This will be used as base for future enhancement in PMSM jacket cooling for high speed generator.

A novel analysis for heat transfer enhancement in a trapezoidal fin wetted by MoS2 + Fe3O4 + NiZnFe2O4- methanol based ternary hybrid nanofluid

Nanofluids have grasped the attention of numerous researchers due to their enhanced thermal properties and heat transport performance. Recently, the mixture of ternary nanoparticles is exploited to synthesize a unique nanofluid that has superior thermal features. In this regard, the effects of internal heat generation, thermal radiation, and convection on a steady heat transfer mechanism in a trapezoidal fin wetted with ternary hybrid nanofluid are scrutinized in this investigation. Additionally, this research explores the comparative assessment of thermal and heat energy variations in both dry and wet conditions. The non-dimensional transformations result in the governing differential equation and boundary conditions being reduced to dimensionless expressions of an ordinary differential equation (ODE). A numerical method Runge–Kutta-Fehlberg's fourth-fifth is employed to solve the yielded differential equation of temperature. In addition, the effects of pertinent thermal variables on the thermal profile of the fin are explored graphically. The outcomes reveal that improving the surface radiation variable lowers the thermal profile, and the same behavior is detected for the surface convection parameter. Furthermore, the fluids comprising ternary nanoparticles have the greatest thermal variation. Also, the longitudinal trapezoidal fin has the optimum performance, and higher heat transfer characteristics compared to the typical straight fin.

Energy transfer of a fin wetted with ZnO-SAE 50 nanolubricant:An application of α-parameterized differential transform method

In the field of mathematical physics, this research focuses on the new conservation forms of the nonlinear fin equation. Nanolubricants with improved thermo-physical characteristics can enhance heat transfer performance in the cooling system. Also, the nanolubricant minimizes the corrosion and abrasion of working parts in bore-piston, gaskets, and valve mechanisms, which is not generally witnessed in other nanofluids. Encouraged by these facts, the novel heat transfer liquid zinc oxide-Society of Automotive Engineers 50 (ZnO-SAE 50) nanolubricant is considered in this investigation to explain the thermal dispersion in the straight rectangular fin. In addition, the convection-conduction heat transfer of a fin wetted with ZnO-SAE 50 nanolubricant is investigated in the existence of internal heat generation. A mathematical model involving the energy equation is developed and converted to its dimensionless form using appropriate dimensionless terms. The transformed equation is subjected to analytical approximation using the α-parameterized differential transform method (α-PDTM). The present research provides significant outcomes. The augmentation of thermal distribution in the fin is caused by the decreasing magnitude of the wet parameter. The thermal discrepancy is affected by lowering the convective-conductive factor, which results in higher temperature distribution.

Twisted-fin parametric study to enhance the solidification performance of phase-change material in a shell-and-tube latent heat thermal energy storage system

Abstract Phase change material (PCM) is considered as one of the most effective thermal energy storage (TES) systems to balance energy supply and demand. A key challenge in designing efficient PCM-based TES systems lies in the enhancement of heat transmission during phase transition. This study numerically examines the privilege of employing twisted-fin arrays inside a shell-and-tube latent heat storage unit to improve the solidification performance. The presence of twisted fins contributes to the dominating role of heat conduction by their curved shapes, which restricts the role of natural convection but largely aids the overall heat-transfer process during solidification. The heat-discharge rate of twisted-fin configuration is increased by ∼14 and ∼55% compared to straight fin and no fin configurations—leading to a reduction in the solidification duration by ∼13 and ∼35%, respectively. The solidification front at various times has also been assessed through a detailed parametric study over the fin height, fin pitch number, and fin thickness. Over the range of values assumed, the fin height is the most dominant parameter – increasing the heat-retrieval rate from 10.0 to 11.4 W and decreasing the discharge time from above 3600 to 2880 s by varying the fin height from 2.5 to 7.5 mm.

Thermal performance analysis of a 20-feet latent cold energy storage device integrated with a novel fin-plate unit for building cooling

A 20-feet latent cold energy storage device integrated with a novel fin-plate unit was used to cool a 400 m2 building space, in which the cold energy could be generated from renewable energy, industrial waste cold, or off-peak electricity. Due to the low thermal conductivity of n-pentadecane, a novel fin-plate unit was designed to improve the heat transfer rate of PCMs especially for the restricted charging process. Meanwhile, energy storage efficiency of the device under different operating parameters was analyzed. The results showed that the introduction of straight fin significantly accelerated the solidification process of encapsulated PCMs. Compared with straight fin, the branch fin (lBranch = 30 mm, α = 120°) that had the same volume was found to shorten 27.7% of the charging time. While such branch fin could only shorten 2.8% of the discharging time, which might be attributed to the balance between the contribution and the restrictiveness for heat transfer caused by the fin. The small inlet velocity of 0.03 m/s was shown to contribute to a high energy storage efficiency of 86.83% and a long output time of 12.08 h. The results of this work were expected to provide the foundation for building the low-carbon architecture.

The Effect of Fin Shape on the Heat Transfer and the Solution Time of a Microchannel Evaporator in a CO2 Air Conditioning System-A Numerical Investigation.

Numerical simulations on the fin shape of a microchannel evaporator in a CO2 air conditioning system were performed at the inlet evaporative temperature of 10 °C and the vapor quality of 0.61. Two types of fin shapes were dealt with: the straight fins and V-fins. The numerical results were verified by the experimental data. For the system under consideration and for the same heat transfer area and the heat transfer coefficient for the air side in the microchannel evaporator, the effect of the fin shape on the heat transfer was not different; however, the solution time and the physical memory for the straight fins were 1.3 and 1.45 times compared with the V-fins, respectively. Therefore, the V-fin shape should be used for numerical simulation to compare it with the straight fin shape. In this study, the evaporation of the refrigerant in the microchannel evaporator took place in four passes. The normal heat flux from the air through the fins and tubes was almost reached at 1550 W/m2 at the evaporative temperature of 10 °C. The results obtained from the experimental data were in good agreement with those obtained from the numerical results, with a deviation of less than 10%.

Solving the Problem of Liquid Metal Convective Heat Transfer in the Helical Coordinate System

We show a way to solve the problems of hydrodynamics and heat transfer in helical medium flow channels in the helical coordinate system. Specifically, such problems are solved for the buoyant liquid metal flow in a heated helical fin ring-shaped channel. The problems are related to heat transfer in the flow process over the fuel pin located within the fuel bundle finned in the liquid metal nuclear reactor core. The article shows the tensor analysis derivation of the mass-, momentum-, and energy-conservation equations as applied to a liquid metal medium in the helical coordinate system. We assume as the basis the well-known equations for a cylindrical system proposed to be added, with extra terms arising in the process of transition to the helical coordinate system. In line with the proposed technique, numerical computation of the velocity, pressure, and temperature profiles in the process of turbulent liquid flow in a helical fin ring-shaped channel was performed. Two computation cases are compared: with straight and twisted (helical) fins. Examples of the computation data show the measurable effect of a twisted fin upon flow and heat transfer parameters. The available gap between the fin and the external tube enhances the vorticity effect.

Fractal Geometry as an Effective Heat Sink

"How long is the coast of Britain?" was the question stated by Mandelbrot. Using smaller and smaller rulers the coast length limits to infinity. If this logic is applied to the fractal heat sink geometry, infinite cooling capacity should be obtained using fractals with mathematically infinite surface area. The aim of this article is to check this idea using Richardson extrapolation of numerical simulation results varying the fractal element length from one to zero. As expected, the extrapolated heat flux has a noninfinite limit. The presented fractal heat sink geometry is non-competitive to the straight fins.

Characteristics of thermal plume from an array of rectangular straight fins with openings on the base in natural convection

Straight rectangular fins with openings in the base surface in natural convection exhibit greater heat transfer than rectangular fins without openings in the base. In this paper, thermal plume arising from such fin configuration used as a heat sink for natural convection cooling of light-emitting diode (LED) grow lights is investigated using three-dimensional conjugate laminar flow simulations. Understanding of plume characteristics is crucial in optimizing the cooling performance as well as optimal placement of grow lights from ceilings and walls in proximity. A prototype LED grow light was designed and experimentally measured to assess the cooling performance, and numerical simulations were conducted to investigate the plume structure. The results showed that openings in the base enhanced vertical draft of air, mixing, and overall heat transfer rate. It was found that local pressure gradient is proportional to the degree of mixing of ambient air into the plume. Low pressure regions around the fins and channels showed upward convection of plume mass and a high pressure region below the fins indicated higher concentration of denser air mass. High pressure gradients were observed in the openings, which further justifies the significance of openings in improving mixing of ambient air with the plume to enhance heat transfer.

Thermo-hydraulic performance investigation of heat pipe used annular heat exchanger with densely longitudinal fins

To enhance the heat transfer capacity of the condenser end in the heat pipe heat exchanger, heat transfer and flow characteristics investigations of three densely longitudinal fin-equipped annular heat exchangers have been carried out by using a combined method of experimental testing and numerical simulation. One of the heat exchangers as a baseline is featured by the long straight fins. The other featured folded fins and arc-shaped fins, in which 40 rows of short fins were arranged just like the blade-lattice. The attained results showed that the short fold fins and arc-shaped fins had Nusselt numbers that were 27% and 35% higher than the long straight fins, and had friction factors that were 1088% and 2209% higher than the long straight fins. It indicates that the dense fin arrangement has a relatively limited influence on the wall temperature and overall heat transfer capacity. However, the friction loss is significantly sensitive to the fin arrangement because of the severe flow drag and flow separation induced by the blade-lattice like fins. The thermo-hydraulic performance evaluation suggests that the three densely longitudinal fins are suitable for different application scenarios with different heat transfer and pressure loss requirements. This work serves as a reference for the heat exchanger design in the heat pipe-based thermal power conversion system.