Fin Spacing Research Articles

Entropy generation analysis of a dual-height plate-fin heat sink with Nanofluid coolant applying two-phase mixture model

In this work, the two-phase mixture model is applied to solve the velocity field, the pressure field and obtain the entropy generation rates in a dual-height plate-fin heatsink. The governing equations were solved using the second-order upwind discretization scheme as well as SIMPLE scheme used in coupling the pressure and velocity fields. The Re, nanoparticle concentration (ψ), secondary fin height (hsf), and fin spacing (dsf) were considered within the ranges of 500-2000, 0%-1%, 5 mm-17.5 mm, and 0.25 mm-0.5 mm, respectively. The results demonstrated that S˙th almost decrease by 30% as hsf increases from 5 mm to 17.5 mm. The increase in hsf escalates S˙fr by 308% and 238% at Re numbers of 500 and 2000, respectively. In addition, the escalation of Re from 500 to 2000 increases S˙fr by 2125% and 1748% for hsf 5 mm and 17.5 mm, respectively. The fin spacing analysis revealed that the lowest S˙th and highest S˙fr belong to dsf=0.5 mm. The lower the dsf the higher the backward flow and mixing flow at the heatsink outlet, thereby delay in flow passage and intensification of S˙th and S˙fr.

Numerical Analysis of a TEG and mPCM Enhancement System for BIPVs Using CFD

Building-integrated photovoltaics (BIPVs) are the most promising systems for net-zero energy buildings. However, there are few practical cases because of shortcomings, such as the lack of solar tracking and the rapid rise in PV surface temperature. Therefore, methods of increasing the efficiency of BIPVs have been proposed and studied. These include using phase change material (PCM) or heat fins, wavelength selection, decreasing the PV surface temperature, or using a thermoelectric generator (TEG) and convection cooling to utilize the waste heat from the PV. Many preceding studies have been conducted on TEG and convection heat dissipation methods to utilize as much waste heat as possible. Therefore, in this study, a TEG–PCM hybrid system using mPCM was proposed to improve constructability. Herein, the appropriate phase change temperature of the PCM, the heat fin spacing in the PCM container, and the TEG arrangement were analyzed through computational fluid dynamics (CFD)-based simulations. The appropriate melting temperature of the PCM, the heat fin interval, and the arrangement of the TEG for the proposed system are 25 °C, 20 mm, and 140 mm, respectively. In order to achieve optimal efficiency, it is necessary to consider an appropriate amount of heat transfer, and it has been confirmed that if there are too many thermoelectric elements, the opposite effect occurs.

Performance Comparison of Mini-Rectangular Fin Heat Sinks Using Different Coolants: Supercritical CO2, Water and Al2O3/H2O Nanofluid

Mini-channel heatsinks have proven useful in removing high heat fluxes from microelectronic devices. However, further miniaturization of electronic devices requires significant enhancement in the mini-channel heatsinks’ thermohydraulic characteristics, which depend greatly on the coolant and geometrical configuration of the channel. Therefore, the current study explores the potential of mini-channel heatsinks’ using different coolants (water, nanofluid and supercritical carbon dioxide) and various channel configurations. The effect of various channel configurations on the thermohydraulic characteristics of the mini-channel heat sinks is evaluated numerically for different coolants employing three flow rates (17 g/s, 34 g/s and 50 g/s). Hence, the effects of fin height, spacing and thickness, and mass flow rate on the overall heat transfer coefficient (CHT) and pressure drop (ΔP) are reported for the abovementioned coolants. It is found that increasing the mass flow rate increases both the CHT and ΔP. It is also noted that increasing the fin height and spacing decreases both the CHT and ΔP, as opposed to increasing the thickness, which causes both the CHT and ΔP to increase. Among the three coolants used, the sCO2 shows superior performance compared to the water and nanofluid and this based on higher CHT and lower ΔP. Moreover, the performance evaluation criterion (PEC) for the sCO2 is higher than that for the water and nanofluid by 53% at 17 g/s flow rate and 243% at 50 g/s flow rate.

Investigation of heat transfer performance within annular geometries with swirl-inducing fins using clove-treated graphene nanoplatelet colloidal suspension

The paper investigated the benefits of having fins that induce swirling flow within an annular passage. The importance of the vortical structures produced using different fin angles and flow velocities in heat transfer was studied. The combination of swirling fluid with recirculation on heat transfer within an annular domain was not fully understood, and this paper aims to address that gap. The 10°, 20°, 30° and 40° angled fins were investigated to understand the changes in heat transfer performance as fluid recirculation becomes more dominant as angles become steeper. The usage of CGNP colloidal suspension was investigated for its potential benefits in heat transfer in a domain with angled fins. The CGNP concentrations of 0.025, 0.075 and 0.1 mass % were used as part of this investigation. Higher concentrations of CGNP increased the overall heat transfer coefficient. A more compact fin spacing improved heat transfer performance at the expense of increased pressure drop. Fin angles of 20° and 30° yielded poor heat transfer performance in the transitional flow regime (2000 < Re < 3000) due to the smaller swirling longitudinal vortices being insufficient in promoting fluid mixing from the thermal boundary layer into the freestream.

Modelling of the temperature profile of heat sinks for a thermoelectric cooler module

Thermoelectric refrigeration achieves cooling through Peltier and Seebeck effect. Heat sinks attached to the hot and cold sides of the thermoelectric module help to efficiently dissipates and absorb heat. This research modelled the temperature profile across a heat sink and its optimization for a thermoelectric refrigeration application. Simulation was carried out using MATLAB to visualize the performance of the heat sink. The optimization was done using FMINCON in MATLAB by setting upper and lower bounds to satisfy space and volume requirement. The optimum values for the hot and cold heat sink geometry obtained using FMINCON tool in OPTIMTOOL box in MATLAB, yields number of fins as 10, fin spacing as 0.003m, the fin thickness as 0.002m and fin length as 0.015m with an optimum temperature of -0.8639.

Study of combined effect of natural convection and radiation heat transfer from annular finned vertical cylinder

AbstractThe present numerical study reports the combined effect of natural convection and radiation heat from a vertical cylinder with annular fins. The study involves simulation for laminar as well as turbulent regimes. For the present study, Rayleigh's number is varied in the range , emissivity in the range , and the fin spacing ratio (s/d) in the range . The radiation heat transfer has been found to share a considerable amount in the total heat transfer of the system for the laminar regime, but in the turbulent regime, its effect is minimal and can be neglected. When the fin spacing ratio is reduced, the total heat transfer increases for both the turbulent and laminar flow conditions. But the radiation heat increases with a reduction in fin spacing ratio for laminar and in case of turbulent flow radiation heat rate reduces with a reduction in s/d ratio. For the range of Rayleigh numbers considered in the present study, the Nusselt number increases with the increment of the fin spacing ratio. Thus, it can be concluded that there is a remarkable enhancement in the heat transfer rate in laminar cases with the fins. For turbulent cases, the fin efficiency lies between 40% and 50%.

CFD analysis and environmental assessment on the heat transfer and flow of the pure water or water/silver Nano fluid coolants in a plate-fin heat sink applying two-phase mixture model

Environmental impacts are the consequences caused by the elementary flows on human health, plants, and animals (ecological health) or by the future availability of natural resources (resource depletion). The heat transfer characteristics of a plate-fin heatsink were investigated using a 3-dimensional numerical analysis based on the two-phase mixture model. The effect of using NF, fin spacing, and fin height on the performance of the system were studied considering the constant heat flux of 100 kW/m2 at the bottom of heatsink and NF inlet temperature of 300 K. The results showed that the increase in the secondary fin height (hsf) from 5 mm to 17.5 mm leads to increase in the pressure drop by 11.6%, 52%, to improve the heat convection coefficient (h) by 32.92%-23.84%, and consequently reduces the central processing unit (CPU) mean temperature by 4.31% and 2.34% for Re=500-2000. The maximum performance evaluation criterion (PEC) was obtained as 1.11-1.05 at Re numbers of 500-2000 for heatsink with hsf=12.5 mm. In addition, the optimum location for the secondary fin was determined to be at the mid-space of two primary fins (dsf=0.5 mm) which leads to improving h by 18%-5% at Re numbers of 500-2000 as compared to other fin spacing scenarios. Moreover, the intensification of nanoparticle concentration (ψ) leads to improve h by 15.71%-17.21% for Re=500-2000. Besides, the escalation of ψ decreases the pressure drop by 14.18% for all Re numbers. The PEC of the system with hsf=12.5 mm, ψ=1%, at Re=2000 was obtained as the highest PEC of 1.226 among the other studied cases. According to the design, the heat sink has an environmental impact of 0.5233.

Performance analysis and structural optimization of a finned liquid-cooling radiator for chip heat dissipation

With the rapid development of computer chips with high heat flux, efficient chip cooling is becoming crucial. In this study, a finned water-cooled radiator is developed and its operational performance is tested through experiments. Furthermore, the finned water-cooled radiator heat dissipation model is established using COMSOL software, and then verified experimentally. The effects of the cooling water inlet and outlet positions, fin height, thickness, and spacing on the thermal resistance and flow resistance performance of the radiator are investigated. Based on this, the radiator structure is theoretically optimized and the required cooling water conditions for maintaining the functioning of the chip at its safe temperature are determined. The central arrangement of the cooling water inlet and outlet type performs better than the traditional diagonal arrangement, and the optimal fin-covered plate area of the radiator is almost equal to the chip area. A fin height of 5 mm, fin thickness of 0.5 mm and fin spacing of 1 mm are recommended. Furthermore, the required cooling water operational conditions corresponding to chip heat flux are considered and the fitting relationship between the cooling water flow and pressure drop is catalogued, which may provide guidance for future cooling system designs.

Parametric investigation of internal Y-shaped fin configurations under natural convection in a concentric annulus

Natural convection heat transfer inside concentric annular enclosures has been well researched for decades. Such enclosures have been employed as intermediate layers between fluid streams in heat exchangers, particularly in latent heat thermal energy storage applications. Convection heat transfer coefficients originating from natural convection are relatively low, which drives the need for heat transfer enhancements by using extended surfaces (e.g., fins, heat sinks). In this study, numerical simulations are performed to investigate the natural convection heat transfer inside a concentric annulus in the presence of Y-shaped fins. Each Y-shaped fin has four important geometric parameters: (i) length of the fin base a, (ii) length of the fin branches b (i.e., the V-section), (iii) primary fin spacing angle θ, and (iv) secondary fin angle or branch angle α. Steady-state simulations are conducted using COMSOL Multiphysics® with constant temperature boundary conditions to generate the laminar natural convection profiles in the enclosure filled with air. The average Nusselt numbers, calculated at both the inner and outer walls of the enclosure, are used to gauge the heat transfer. The model is built with thin layer approximated fins first and subsequently compared to a modified model with fins with finite thickness. The optimized case using the thick fin model is found to yield a percent increase in Nu of 358.8% compared to the case with no fins. Lastly, the entropy generation is considered to determine the second law efficiency of the system, which is approximately 91%.

CFD analysis of phase-change material-based heat storage with dimple-shaped fins: evaluation of fin configuration and distribution pattern

Abstract Phase-change materials (PCMs) have a remarkable potential for use as efficient energy storage means. However, their poor response rates during energy storage and retrieval modes require the use of heat transfer enhancers to combat these limitations. This research marks the first attempt to explore the potential of dimple-shaped fins for the enhancement of PCM thermal response in a shell-and-tube casing. Fin arrays with different dimensions and diverse distribution patterns were designed and studied to assess the effect of modifying the fin geometric parameters and distribution patterns in various spatial zones of the physical domain. The results indicate that increasing the number of dimple fins in the range of 8–32 results in faster heat storage rates by up to 8.7% faster than they would be without the dimple fins. Further improvements of approximately 1.4, 1.2, 1.1, and 1.0% can be obtained by optimizing the position of the first fin section, the spacing between other fin sections, the fin spacing based on the aromatic algorithm, and the use of the staggered fin distribution. The heat storage rate is improved by almost 12% for the best case compared with that of the no-fin case.

A Comparative Numerical Study of Estimation of Velocity Components in Mixed Convection Through Vertical Shrouded Plate Finned Channel

Abstract An attempt has been made to investigate the performance of two methods of estimation of free and forced convection velocity components present in mixed convection. For this present analysis, a vertically configured shrouded plate finned channel is considered. From the literature, it is observed that in the solution of mixed convection problems related to the various engineering applications, proper estimation of induced velocity and fan/pump velocity plays a vital role. For this cause, segregation of the velocity components of free and forced convection present in the mixed convection becomes important. There exist two methods available in the literature, namely, first, the natural convection computational fluid dynamics method (NCM) used in the mixed convection computational fluid dynamics analysis under the same thermal and geometrical conditions, and second, forced convection decoupled method (FDM) applying the same pressure drop in forced and mixed convection across the channel. Results of this study reveal that if the free or induced velocity component present in the mixed convection is assessed based on the forced convection decoupled method, the pumping power results may be more precise than the natural convection computational fluid dynamic method as in the later method calculation of the forced convection velocity component is underpredicted. The natural convection velocity component evaluated through NCM varies 33% to 65.7% from the FDM based on the shroud clearance for the constant fin heights of 0.04 m. This variation is as high as 98% and 96% in the case of the larger nondimensional fin spacing of 0.3 and 0.5, respectively. A correlation of overall Nusselt number is suggested for a vertically configured shrouded dual-height plate finned channel evaluating appropriate Reynolds through the forced convection decoupled method.

A novel passive solar vertical-finned-thermocatalytic-Trombe wall system for air purification and heating

In this study, the combination of thermocatalytic oxidation technology with finned heat transfer technology was proposed to produce a novel passive solar vertical-finned- thermocatalytic-Trombe wall (VFTC-Trombe wall) system. The numerical model coupled with flow and heat transfer, convective-diffusion and catalytic reaction kinetic processes was established. The influences of fins geometry and environmental parameters on thermal and air purification performance were evaluated. The main findings are as follow: Both the purification efficiency and total efficiency increase with fins height. As the fins spacing rises, thermal, purification and total efficiencies all show maximum values. By adding the vertical fins in the channel, the purification performance improvement of the TC-Trombe wall system can be realized without sacrificing thermal performance. The optimum purification efficiency improves more than 1.5 times compared to that without vertical fins. The vertical fins have more significant effect on the purification performance than the thermal performance. At fins height h = 40 mm, fins spacing s = 16.67 mm, and solar radiation intensity I = 400 W/m2, the maximum total efficiency of VFTC-Trombe wall system reaches 65.11%, which is relatively improved by 31.9% compared to the TC-Trombe wall system without vertical fins. In addition, the impact of ambient temperature on thermal performance is more significant than that on purification performance.

Solidification performance analysis of bionic spider web vertical latent heat system based on response surface method optimization

The vertical sleeve phase change heat storage unit filled with RT55 is taken as the research object. Aiming at the low thermal conductivity of phase change materials, a vertical latent heat storage sleeve (LHTES) with spider web structure optimized by response surface method is proposed to improve the solidification performance of latent heat storage system, and the phase change heat transfer process is simulated by numerical simulation method. The enhanced heat transfer characteristics of phase change material (PCM) unit in casing with different spider web fin sizes are studied. The results show that reasonably changing the fin spacing, main fin thickness and branch fin thickness of spider web shape fins can reduce PCM solidification time and evaluation temperature correspondingly, and increase the heat dissipation of LHTES. Combining PCM solidification time, heat release of LHTES and PCM average temperature as evaluation indexes, the solidification heat performance of LHTES is comprehensively analyzed, and the geometric parameters of fins are optimized by response surface method (RSM), and the optimal solution is obtained as follows: the spider web fin spacing (H) is 30.00 mm, the spider web main fin thickness (m) is 3.91 mm, and the spider web branch fin thickness (L) is 2.64 mm. Finally, the economic analysis finds that the spider web structure LHTES has high economic efficiency.

Effect of Rectangular Fins on Heat Transfer Characteristics of Domestic Cookware

Working process of domestic gas stoves primarily depends on the heat transfer phenomenon between gas flame and the bottom of the cookware. Various energy losses during this heat transfer results in low thermal efficiency. This work focuses on improving heat transfer ability of cookware, thus enhancing thermal-efficiency. Increase in rectangular fin height H causes increase in thermal efficiency value up to a certain limit after which a decreasing trend is observed by both numerical and experimental results. The fin height H=14.6 mm is considered optimum value for thermal efficiency. After H=14.6 mm, the maximum temperature value of fins shows a constant trend up to certain limit. Fin width variation follows a linear increase trend as the width increases up to 5 mm where fluctuation in efficiency stops. Max temperature of fins shows good agreement with increase in fin width in both numerical and experimental values up to W= 4.8 mm after which 10c temp loss occurs due to localized heat losses. Lastly fin spacing is verified against overall thermal efficiency and gradual; decrease is found in efficiency with increasing spacing due to formation of hotspots in between each fin. Lowest efficiency of 57% observed at fin spacing of 7 mm.

THERMAL ENHANCEMENTS OF A LED BASED AUTOMOTIVE HEADLAMP

Light Emitting Diode (LED) is a new kind of light source that is quickly being used into automotive lighting systems. In recent years, there have been increased expectations placed on vehicle headlamps, including that they not only be fully functional, affordable, and long-lasting, but also stylish, energy-efficient, and environmentally friendly. Since LED light sources are long-lasting, highly efficient, and energy-efficient, small in size, etc., they are frequently utilized in headlamps, turn signals, brake lights, position lights, etc. and will soon dominate the automotive light source industry. Although it has a greater energy conversion efficiency, the thermal management of LED headlamps is still a problem. In this research, the response surface method is used to optimize the heatsink designs for LED automotive headlamp module. The finite element (FE) approach and numerical simulation are used to model the test samples temperature distribution. Then, in order to maximize the heatsink potential for thermal dissipation, we tested different types of material, and used the response surface method. The LED headlamp hot spots decrease by 2 to 8 degrees when the heat sinks thickness, fin spacing, and height are optimized and decrease by 7.64 degrees when the heat sink and PCB substrate are made of 6063 aluminum alloy and AlN, respectively.

Overall Pressure Loss and Heat Transfer Performance of Additively Manufactured Offset Strip Fins Used in Compact Heat Exchangers

Abstract Preliminary heat exchanger design relies heavily on correlations for overall heat transfer and pressure drop performance, particularly for heat transfer augmentation features such as fins. Extensive work has been performed by the research community to develop these correlations for the numerous designs. However, with the new technology of metal additive manufacturing and the resultant surface roughness, the traditional correlations and design considerations related to performance need to be adjusted. As a result, two metal additively manufactured offset strip fin heat exchanger geometries with different fin spacing are studied for heat transfer and pressure drop performance and compared with traditional correlations. Deviations between the additively manufactured geometries and previous correlations for smooth fins are found and are further amplified as the surface roughness-to-hydraulic diameter ratio is increased. Furthermore, the surface roughness from the additive process results in a constant friction factor behavior at high Reynolds numbers, which is unlike behavior observed for conventionally manufactured fins. Considerations for both the laminar and turbulent flow regimes are needed for correct performance prediction. A final offset strip fin geometry with a change in the fin spacing every third of the way through the flow path is tested. This study found that the orientation of fin spacing, wider spaced to tightly spaced or tightly spaced to wider spaced, did not have a significant effect on pressure drop or heat transfer. However, the study found a method for predicting the performance which will become important as additive manufacturing increases the complexity of heat exchanger designs.

Solidification of an annular finned tube ice storage unit

Increasing building energy consumption rates is leading to significant surcharges for both the peak grid loads and the peak building energy consumption costs. The power load mismatches between user demands and energy supplies can be effectively reduced by ice storage systems. In order to solve the problem of heat transfer attenuation in the cold storage process. This study used a two-dimensional axisymmetric transient model of an annular finned tube ice storage unit to investigate the solidification characteristics and heat transfer rates with water as the storage medium and ethylene glycol as the heat transfer medium. The model was validated against experimental data. The calculations then investigated the effect of the annular fin height and fin spacing on the phase change and the solidification front velocity. The results show that increasing the fin height and decreasing the fin spacing both increase the ice storage solidification rate and improve the cold storage capacity. At a fin height of 50 mm, its solid phase fraction was 4.96 times larger than that of the bare tube. The cold storage capacity with the 50 mm high fins is more than 3.68 times that without fins at 480 min. The 4 mm fin spacing has a 26.3% greater cold storage capacity than the 12 mm fin spacing.

Thermo-Hydraulic Analysis of Slightly Inclined Finned Channel under Natural Convection

The influence of slight inclination, ‘α’ (i.e., 10°, 15°, and 20°) of the channel comprised of shrouded vertical rectangular non-isothermal fin array has been computationally investigated. Simulations are performed to obtain the convective coefficient of heat transfer for the different dimensionless fin spacing (S*= 0.2, 0.3, 0.5), non-dimensional fin tip to shroud clearances (C*= 0.1, 0.2 and 0.3), Grashof numbers (Gr= 1.08×105, 4.42×105 and 11.5×105), fin lengths (L= 0.25m and 0.5m) and fin heights (H= 0.025m, 0.04m, and 0.055m). Hydrodynamic behavior of the fluid indicates that a significant amount of flow reversal occurs near the entrance of the channel at very low inclination which vanishes with the increase in inclination. Further, at higher length, reverse flow is found to occur only in the clearance zone. An increase in the value of ‘α’ from 10° to 20°, results in enhancement of convective coefficient up to a maximum of 161%. An increase in the value of fin spacing from 0.2 to 0.5 results in the enhancement of the convective heat transfer coefficient. At α= 15° and 20°, the heat transfer is enhanced by 84.1% and 101.6%, respectively, while at α=10°, the same is reduced by 33.3%. At lower fin spacing (S*<0.3) increase in C* tends to reduce the efficiency. Further, the efficiency of the finite conductive fin is found to reduce by almost 8% with an increase in Grashof number.

Numerical simulation of the thermal performance of a wavy fin configuration for a straight fin array

Fins over the years have been used as heat exchangers for exchanging heat generated in engineering machines or systems, between the system surface and the ambient air. However, the challenge of thermal design for the best geometry of heat fin prompted the study, to determining the performance of a wavy and straight fin projecting vertically from a horizontal base, by comparing their rate of heat transfer. In this study a free convection steady state numerical analysis was carried out using Solidworks 2018 flow simulation application, which is based on finite volume method of Computational Flow Dynamics (CFD). The numerical analysis was carried out on three different fin array configurations, all of the same fin spacing or separation distance. The three fin array modeled includes the straight and wavy fin of fin height, 35mm and spacing, 14.2mm respectively. The third fin was a straight fin of height, 50mm equivalent of the effective wavelength of the wavy fin, but of same fin spacing. Aluminum metal was selected as the material, and the simulation was done using air as the fluid, of temperature, and convective heat coefficient, 27°C and 20W/mK respectively. Simulation was carried out at different temperatures for each geometry, ranging from 45°C – 120°C. The results showed that the difference in the rate of heat transfer for the wavy fin and straight fin were close at low temperatures, but significantly increased to about 28% at higher temperatures in favor of the wavy fin. The third fin had an insignificant 9% heat transfer rate higher than the wavy fin but with 43% additional height, thereby occupying more space. It is established from this study that wavy fin array possesses higher convection heat transfer performance than the straight rectangular fin array. Therefore, in a bit to achieve high performance heat transfer with limited space, a wavy fin array is recommended.

Optimization of an air-cooled heat sink for cooling of a solar photovoltaic panel: A computational study

Rapidly increasing global energy demand and resulting climate change effects have enhanced the integration of renewable systems such as solar photovoltaics into the built environment. For countries with hot climates, despite vast applications and numerous technological advancements, lower efficiencies of the solar panels due to high temperature is still a major disadvantage affecting the feasibility of using photovoltaic technology. This study analyses the cooling performance of air-cooled heat sinks for the climate of Dubai, UAE, using Computation Fluid Dynamics (CFD). A stepwise optimization study was conducted to investigate the effects of varying fin spacing, baseplate thickness, fin height and fin thickness on the heat dissipation rate. Further, the elemental properties of the heat sink were studied by altering its material to aluminium. The base-model heat sink could reduce PV cell temperature by 27 °C in an ambient temperature of 42 °C. The optimized fin spacing, baseplate thickness, fin height and fin thickness of 7, 0.0025 m, 0.12 m and 0.002 m further reduced the average panel temperatures by 3.5%, 4% and 9% respectively. The use of copper as an effective heat sink material was concluded compared to aluminium that conversely increased the average panel temperature by 2% despite the use of optimized heat sink structure.