Conductivity Of Fin Research Articles

Application of bionic topology to latent heat storage devices

Latent heat storage is employed to address the intermittent supply of renewable energy, and enhancing heat transfer in phase change materials (PCMs) is pivotal for achieving effective heat storage. Currently, the predominant method for improving heat transfer is through the integration of high thermal conductivity fins into heat storage devices. This study introduces an innovative design of a three-tube phase change heat storage device created through bionic topology optimization. The impact of parameters such as penalty factors and filtering radius on the topology structure is analyzed, and the optimal range of fin volume fraction is determined based on energy storage density and energy storage time. Considering the influence of natural convection on heat transfer properties, four distinct heat storage models, including topology-optimized fins, are compared. The heat transfer and flow properties during the processes of melting and solidification, as well as their field synergy, are investigated. The study reveals that the optimized fins exhibit more bionic fractal structures and a larger, more uniform heat transfer contact area. Compared to traditionally optimized fin structures, this research reduces the heat storage time of the three-tube heat storage device by 21.96 % and the heat release time by 38.13 % without compromising the maximum heat storage capacity. The topology-optimized fins demonstrate a fractal dimension similar to natural fractal structures such as branches, leaf veins, antlers, and snowflakes. This study presents a novel bionic structural design approach for high-performance latent heat storage systems.

Effect of porous fin parameters on the turbulent natural convection heat transfer in the side-heated cavity containing the internal heat source

In order to study the effect of porous fin parameters on the natural convection heat transfer in the side-heated cavity containing the internal heat source, the influence of the structural parameters of porous fins (length of porous fins l, installation position of porous fins s, Installation angle of porous fins θ) and the physical property parameters of porous fins (effective thermal conductivity Ke, Darcy number Da) on the natural convection heat transfer in the cavity was numerically analyzed by arranging a porous fin on the hot wall. The effect of the coupling effect of the structure parameters of porous fins was analyzed by the response surface method, and it was found that the coupling effect of the installation position and installation angle of porous fins had the most significant effect on the convective heat transfer in the cavity, the combination of the structural parameters of porous fins with the optimal convective heat transfer effect is l = 0.053 H, s = 0.373 H, and θ = 93.21°, which increases the average Nusselt number of the hot wall by 38.72% compared with no-fin structure; The effect of Darcy number and effective thermal conductivity of porous fins on the average Nusselt number of the hot wall surface is analyzed. The results of the study can guide the study of solar radiation in buildings, the internal temperature control of automobiles, and the study of the thermal performance of electronic components.

Enhancing Heat Storage Cooling Systems via the Implementation of Honeycomb-Inspired Design: Investigating Efficiency and Performance

This study presents a novel approach inspired by the hexagonal honeycomb structure found in nature, leveraging image processing algorithms to precisely define complex geometries in thermal systems. Hexagonal phase change material containers and thermally conductive fins were meticulously delineated, mirroring the intricate real-world designs of honeycombs. This innovative methodology not only streamlines setup processes but also enhances our understanding of melting dynamics within enclosures, highlighting the potential benefits of biomimetic design principles in engineering applications. Two distinct honeycomb structures were employed to investigate their impact on the melting process within cavities subject to heating from the left wall, with the remaining walls treated as adiabatic surfaces. The incorporation of a thermally conductive fin system within the enclosure significantly reduced the time required for a complete phase change, emphasizing the profound influence of fin systems on thermal design and performance. This enhancement in heat transfer dynamics makes fin systems advantageous for applications prioritizing precise temperature control and expedited phase change processes. Furthermore, the critical role of the fin system design was emphasized, influencing both the onset and location of the final point of melting. This underscores the importance of tailoring fin systems to specific applications to optimize their performance. Our study highlights the significant impact of the Rayleigh (Ra) number on the melting time in a cavity without fins, revealing a decrease from 6 to 0.4 as the Ra increased from 102 to 105; the introduction of a fin system uniformly reduced the melting time to Ste.Fo = 0.5, indicating fins’ universal effectiveness in optimizing thermal dynamics and expediting the melting process. Moreover, the cavity angle was found to significantly affect the fluid fraction diagram in unfanned cavities but had minimal impact when fins were present, highlighting the stabilizing role of fins in mitigating gravitational effects during melting processes. These insights expand our understanding of cavity geometry and fin interactions in heat transfer, offering potential for enhanced thermal system designs in various engineering applications. Decreasing thermal conductivity (λ) by increasing the fin thickness can halve the melting time, but the accompanying disadvantages include a heavier system and reduced energy storage due to less phase change material, necessitating a careful balance in decision-making.

Heat transfer performance enhancement and mechanism analysis of thermal energy storage unit designed by using a modified transient topology optimization model

The spatial layout of the highly conductive fin and phase change materials (PCM) and the thermophysical properties of PCM are important factors restricting the heat transfer rate of the latent heat thermal energy storage (LHTES). The current fin design concentrates on the limited design space, and rarely adopts the optimizing form of unconstrained structure evolution in the process. So this study proposes a modified transient topology optimization (TO) model to seek the optimal distribution of the fins embedded into PCM subject to the constraints of fin area and specified time. This topology optimization problem is formulated using the density-based material design variable in governing equations, physical constraints, etc. The design freedom and procedural iterative solving of TO model allow for the free evolution of innovative fin structures and elucidate the interaction mechanism between the fin design and physical occurring processes. The double interpolation function, variable regularization, adjoint-based sensitivity analysis and GCMMA algorithm are established to further improve TO model to obtain high-precision solutions. Using above methods, the regular evolution mechanism of fins and physical performance parameters and the trade-off between performance and structure are analyzed. Then, the effects and reasons of pure paraffin (PW) and the adding carbon nanotubes (nPW) on changes in topology structure and performance parameters are also comparatively studied. Finally, by comparing TO-fins with conventional rectangular fins, the superiority of the established method is verified, and the performance improvement mechanism and extent of TO-fins are revealed. Results show that TO-fin LHTES with nPW can achieve better performance than TO-fin LHTES with PW under fewer branches and shorter branch length. The uniform distribution and multi-branch characteristics of TO-fins greatly shorten the heat conduction path, and its local segmentation of whole PCM enhances the local convection effect.

Topology optimization of a rectangular phase change material module

Latent heat storages have numerous times been demonstrated to benefit from including highly conductive fin structures for elevated charging and discharging properties. However, to this point it is still unclear how fins should be designed for optimal charging performance while meeting constraints on minimum storage density and manufacturability. Therefore, in the present work, we use topology optimization to obtain optimal designs for rectangular Phase Change Material (PCM) modules charged by a water flow, based on a conductive heat transfer model for the PCM. The optimal topologies are designed for maximum mean charging power of the PCM over a desired charge time. The optimal designs feature tree-like metal structures with an increased amount of branching for higher power requirements. Moreover, the optimal topologies are compared with straight fins with an equal minimal length scale. This comparison reveals the sub-optimality of the obtained tree-like designs for conduction driven phase-change problems.

Simulation of conductive fins effect on mixed convection heat transfer in a two-dimensional inclined channel using the lattice Boltzmann method

The simulation of the laminar mixed convection heat transfer inside a 2-D inclined channel was investigated here by employing the lattice Boltzmann method (LBM). The channel was equipped with conductive fins. The effects of inclination angle (φ), geometrical parameters (e and A), and a wide range of the Richardson numbers (Ri = 0.1-10) at fixed Reynolds number (Re = 100) on the heat transfer and flow structure were studied. The numerical model was validated by the published benchmark problems. Results were analyzed in terms of isotherms, streamlines, average Nusselt number, and average temperature. It found that the Nu increases with a decrease in the number, height, and width of fins. Results showed that when the channel equipped with 16 fins the reduction in Nu value reaches 62% compared to the empty channel. In addition, at Ri = 1 and N = 8, the Nusselt number decreased by about 52-77% for different fin widths compared to the channel without fins. However, the Richardson number and inclination angle enhanced the heat transfer rate in terms of the average Nusselt number. It revealed that a higher heat transfer rate belongs to the Ri = 10 and φ = 60°. The finding of this work showed the capability of LBM in simulating the mixed convection heat transfer in an inclined channel equipped with fins. A numerical analysis of the results produced a comprehensive set of results that could be utilized to reduce heat transfer. This paper can provide a novel framework for the design of air solar collectors and heat exchange systems.

Optimization of Conductive Fins to Minimize UO2 Fuel Temperature and Radial Temperature Gradient

To further the development of low-enriched uranium fuels, precedence has been placed on delivering the same amount of power while lowering the fuel temperature and radial temperature gradient. To address this, modeling efforts have resulted in a novel design featuring conductive fins of varying thermal conductivities and geometries inserted into the fuel matrix. These conductive inserts were not allowed to exceed 6% of the original fuel volume. This constraint was imposed due to other designs displacing 10% of fuel volume. A parametric study was performed that consisted of 2.56 million BISON simulations involving varying fin characteristics (i.e., fin thermal conductivity, number, and geometry) to determine the optimal geometric configuration for a desired amount of fuel volume displaced. The results from this study show that the thickness and length of each fin affect the fuel temperature and temperature gradient more than varying the number and thermal conductivity of the fins. The parametric study resulted in the development of an optimized combination to produce the lowest peak fuel temperature, lowest radial temperature gradient, and highest temperature reduction for the amount of original fuel volume displaced. The simulations presented in this work will eventually be compared with irradiation experiments of similar fuel designs at Idaho National Laboratory’s Advanced Test Reactor.

Improved Performance of Latent Heat Energy Storage Systems in Response to Utilization of High Thermal Conductivity Fins

Analytical, computational and experimental investigations directed at improving the performance of latent heat thermal energy storage systems that utilize high thermal conductivity fins in direct contact with phase change materials are reviewed. Researchers have focused on waste heat recovery, thermal management of buildings/computing platforms/photovoltaics/satellites and energy storage for solar thermal applications. Aluminum (including various alloys), brass, bronze, copper, PVC, stainless steel and steel were the adopted fin materials. Capric-palmitic acid, chloride mixtures, dodecanoic acid, erythritol, fluorides, lauric acid, naphthalene, nitrite and nitrate mixtures, paraffins, potassium nitrate, salt hydrates, sodium hydrate, stearic acid, sulfur, water and xylitol have been the adopted fusible materials (melting or fusion temperature Tm range of −129.6 to 767 °C). Melting and solidification processes subject to different heat exchange operating conditions were investigated. Studies of thawing have highlighted the marked role of natural convection, exhibiting that realizing thermally unstable fluid layers promote mixing and expedited melting. Performance of the storage system in terms of the hastened charge/discharge time was strongly affected by the number of fins (or fin-pitch) and fin length, in comparison to fin thickness and fin orientation. Strength of natural convection, which is well-known to play an important role on thawing, is diminished by introduction of fins. Consequently, a designer must consider suppression of buoyancy and the extent of sacrificed PCM in selecting the optimum positions and orientation of the fins. Complex fin shapes featuring branching arrangements, crosses, Y-shapes, etc. are widely replacing simple planar fins, satisfying the challenge of forming short-distance conducting pathways linking the temperature extremes of the storage system.

Thermal Energy Storage with PCMs in Shell-and-Tube Units: A Review

The paper presents a survey of the experimental and numerical studies of shell-and-tube systems in which phase change material (PCM) is used. Due to the multitude of design solutions for shell-and-tube systems, the emphasis is placed on double-tube (DT), triplex-tube (TT), and multi-tube (MT) units. Additionally, only single-pass systems are considered. Particular attention is paid to the method of heat transfer intensification. The analysis of the research results begins with the classification of each of the three mentioned systems. The systems are divided according to the angle of inclination, the method of heat transfer enhancement (HTE), the flow direction of heat transfer fluid (HTF), and the arrangement of tubes in the bundle. Moreover, the simplified schemes of the particular research cases are proposed. Then, the works on each of the mentioned systems, i.e., DT, TT, and MT, are discussed chronologically. Finally, in the corresponding tables, details of the discussed cases are presented, such as geometric dimensions, and the type of PCM or HTF used. A novelty in the present work is the precise classification of PCM TESUs as DT, TTH, and MTH. In the literature, there is a lot of discretion in this regard. Second, the methods of heat transfer intensification in the presented PCM TESUs are listed and discussed. Third, unified schemes of design solutions for the discussed PCM TESUs are proposed. The review shows that development directions for shell-and-tube TESUs include systems with high conductivity fins of different shapes, heights, and spacing, several PCMs, and modified shells.

Structure Optimization of Longitudinal Rectangular Fins to Improve the Melting Performance of Phase Change Materials through Genetic Algorithm

In this paper, the structural parameters of longitudinal rectangular fins used in a horizontal shell-and-tube latent heat storage unit (LHSU) are optimized to increase the melting rate of phase-change materials. The influence of natural convection on the melting process is considered. Due to the extremely nonlinear and expensive computational cost of the phase-change heat-transfer-optimization problem, a new coupling algorithm between genetic algorithm and computational fluid dynamics is developed. The effects of the thermal conductivity of fins; the filling rate of fins; and the number of fins on the optimal structure parameters, including the length, width, and position of each fin, are discussed. The results show that when a single fin is inserted in the half-ring region, the optimal dimensionless fin angle is about 0.2, and the optimal dimensionless fin length is about 0.96. The use of optimal single fin can shorten the dimensionless total melting time by 68% compared with the case of no fin, and 61.3% compared with uniformly arranged single fin. When the number of fins exceeds one, each fin should have a specific length (L), thickness (∆), and position (ψ) instead of uniform distribution. The advantage of the optimized fins decreases as the number of fins increases. When the number of fins is four, the optimized fin distribution is almost uniform, and the dimensionless total melting time is only 15.9% less than that of the absolutely uniform fin. The number of fins is a more sensitive parameter affecting the optimal position and structure of fins than the filling rate and thermal conductivity of fins.

Thermal performances of finned heat sink filled with nano-enhanced phase change materials: Design optimization and parametric study

The present numerical study proposes a novel heat sink model with combined NANO- enhanced Phase Change Materials (NANOPCM) and pin fins for the thermal management of electronic devices. The governing equations, model the heat transfer and the NANOPCM melting process, resolved by using CFD software (ANSYS Fluent) based on a finite volume method scheme. First, a comparison between heat sink with and without phase change material (PCM) was carried out. Then, different configurations of finned-heat sinks are studied to investigate the effect of 2 key parameters: the pin fin thickness and the pin fin numbers on the performance of the PCM-based heat sink. Furthermore, the effects of nanoparticles: graphene (GNP), copper oxide (CUO), and aluminium oxide (AL2O3) are investigated. The same volume fraction of nanoparticles 1.65%vol (5%wt weight fraction) was adopted to explore the most efficient NANOPCMs. Further, the impact of nanoparticle weight fractions (5%wt and 7%wt) are also detailed.This study demonstrated that the rise of pin fins volume fraction and the nanoparticles concentration don't improve the heat sink performances; the insertion of 9% pin fins volume fraction and the dispersion of 1.65 %vol graphene showed advanced performances (the operating time has been extended by 2.75 times). The results demonstrated also that the nanoparticle dispersion inside the finned heat sink does not have a significant effect on the thermal response due to the high thermal conductivity of the pin fins.

Large-eddy-simulation of turbulent buoyant flow and conjugate heat transfer in a cubic cavity with fin ribbed radiators

Turbulent convective flow in a cubic cavity is a fundamental model observed in various processes that appeared in environmental and industrial applications. The turbulent fluctuations in the flow field, fluid-solid interaction/coupling, and the transient nature of the problem make it challenging to establish numerical modeling. The turbulent flow and convective heat transfer in a cubic cavity fixed with three fins are studied here. The numerical solutions are obtained through large-eddy simulation with Smagorinsky subgrid-scale model combined with conjugate heat transfer to incorporate temperature distribution in solid fins. The upper and lower walls of the enclosure are differently heated, while the lateral walls are adiabatic, and equally spaced conductive fins are located at the bottom surface. The solutions are initially compared with the numerical and experimental results for validation purposes. Successively, the model is applied to explore the impact of a material (copper) that makes up the horizontal wall on the flow field. We found that the heat transfer essentially alters the turbulent field, and the flow field becomes less homogeneous along the vertical direction. A number of streaky and coherent turbulent structures are found with varying magnitudes. The Q-criterion, second-invariant of the velocity-gradient tensor, predicted that strong vortices occur near the fins and in the surrounding regions of the cavity. Moreover, the energy (entropy) spectral, which plays a crucial role in engineering applications and turbulent theory, is also presented, showing the contribution of each frequency component to the velocity (temperature) variance at a given point. The velocity and temperature fields are found to be anti-symmetric, except close to the front and back walls. The major cause for this is the conducting bottom and fins, which produces thermal stratification in the cavity. The conducting bottom induces the locally unstable thermal stratification in the vicinity of the wall, which intensifies the turbulence as the flow advances toward the temperature-controlled boundaries. Further, the turbulent exchange in the central region is more responsible for the heat transfer than convection that occurs due to the differentially heated walls.

Experimental and numerical study of inverse natural convection-conduction heat transfer in a cavity with a fin

The computational fluid dynamics (CFD) method along with the least squares method and overdetermined experimental data is used to investigate inverse 3D turbulent natural convection-conduction heat transfer in a cavity with a horizontal conduction fin on the vertical hot wall. The main purpose of this study is to predict the unknown heat transfer rate Qh , the heat transfer coefficient on the solid wall, and fluid flow and heat transfer characteristics. To verify the accuracy of an appropriate flow model selected, the root mean square error between the CFD results for temperature obtained from it and all experimental data needs to be the smallest among the selected flow models. The Nusselt numbers obtained also need to be closer to existing correlations or results than those obtained by other flow models. The validation tests through various flow models show that the appropriate flow model for dimensionless distance Sp = Hfp/Lw = 7/24 is the standard k-ε model with dimensionless fin length Lp = L/Lw = 1/4 and Ra = 4.59 × 106 and the zero-equation model with Lp = 2/3 and Ra = 2.33 × 106, respectively. This means that an appropriate flow model may be related to L and Ra. Compared to the isothermal wall assumption, the present results are more accurate, and less experimental temperature data are required.

Porous-fin microchannel heat sinks for future micro-electronics cooling

Porous-fin microchannel heat sinks offering high solid-fluid interfacial areas have the potential to be an integral part of future microelectronic cooling systems. Replacing solid with porous fins reduces the pressure drop penalty of the straight plate-fin microchannel heat sinks. However, prior research has shown that in some cases porous fins adversely affect the thermal performance of the microchannel heat sinks. The reduced effective thermal conductivity of the porous fins compared to the solid ones has been considered the main reason for the reduced thermal performance of porous-fin microchannels. In this work, a detailed study is conducted to assess the feasibility of using porous fins to simultaneously improve the thermal and hydraulic performances of the straight plate-fin microchannel heat sinks. Results revealed that the porous-fin microchannels outperform the solid-fin microchannels at small channel heights. However, at high channel heights, the low effective thermal conductivity of porous fins results in a weak vertical thermal diffusion. Consequently, replacing solid with porous fins degrades the thermal performance of the microchannel at high channel heights. Additionally, the porous-fin microchannels exhibit better thermal performance than the solid-fin microchannels at fin to fluid width ratios above 0.25. The increased coolant mass flow penetrated the porous fin section is the main reason for the enhanced heat transfer rate of the porous-fin microchannels at higher width ratios. Moreover, the porous-fin microchannels offer a lower pressure drop penalty than the solid-fin microchannels under all examined operating conditions. This research confirms the potential of substituting solid with porous fins to simultaneously improve the thermal and hydraulic performances of the straight plate-fin microchannel heat sinks.

Numerical analysis on the geometrical design of liquid cooling based carbon capture by adsorption for higher thermal efficiency

Thermal design and management is important to improve the CO2 capture by adsorption's efficiency, but current studies only consider geometric designs of a specific size. This paper develops a 2D multi-physics model to study how the spacing between two fluid pipes in the adsorbent bed affects the desorption performance, which couples the species transport, fluid dynamics, and heat transfer modules. Specifically, the model involves sandwiching the adsorbent bed between two fluid pipes, which will be parametrically studied in terms of the CO2 desorption performance, with indicators being the thermal efficiency, and the speed of CO2 desorption. Results reveal that a trade-off exists where the desorption speed decreased from 0.9 to 0.05 mol/(m3 s) when the bed height changes from 1 cm to 10 cm, but the thermal efficiency will correspondingly increase from 0.52 to 0.85. Furthermore, a sensitivity analysis on this trade-off situation is conducted by varying the thermal conductivity, regeneration temperature, CO2 feed concentration, and applying thermally conductive fins. Results reveal that increasing the thermal conductivity provides the most reasonable performance improvement characteristics as it halved the desorption time while the specific energy consumption for CO2 capture remains largely unaffected.

Integration of hydrogen storage and heat storage in thermochemical reactors enhanced with optimized topological structures: Charging process

The low density for hydrogen storage can be solved by metal hydrides, and the energy loss for hydrogen storage with metal hydrides can be recovered by the combination of metal hydrides (Mg/MgH2) with thermochemical heat storage materials (MgO/Mg(OH)2) under the different reaction temperatures. However, the poor heat conduction of thermochemical materials limits the heat transfer rate and the implementation of this technology. In this study, an accurate theoretical model of hydrogen charging process in the hydrogen storage reactor assisted with heat storage was developed to accommodate the operating pressure. A novel method to overcome the poor heat transfer problem was proposed by topology optimization of high thermal conductivity fins for matching the heat transfer and reaction rate in the hydrogen storage side with those in the heat storage side. Increasing the average temperature of MgO/Mg(OH)2 was considered for the formulation of the topology optimization problem, and a density-based approach was used. The influence of the conductivity of materials on the topology optimization was discussed. The outcomes displayed that higher thermal conductivity accommodated more heat transfer directions, resulting in a distinct branch structure. Furthermore, the obtained topologies were geometrically reconstructed and evaluated during the hydrogen charging process. Results revealed that the topology optimized geometry had outstanding heat transfer performance, with an obvious improvement in terms of hydrogen charging time over the reactor without fins. This work can provide the theoretical basis for thermochemical conversion processes of hydrogen storage and heat storage, the implementation procedure for topology optimization, and the design guidance of thermochemical reactors for hydrogen storage assisted with heat storage.

Performance evaluation of bifacial PV modules using high thermal conductivity fins

The air cooling method for bifacial PV modules is highly significant for PV power station, especially when the environmental wind speed is low, as the high temperature of bifacial PV modules will reduce the power conversion efficiency and lifetime. In this paper, a new concise and convenient air cooling method (natural convection hybrid air-fin heat sink cooling method) for the bifacial PV module is developed, which uses fins with high thermal conductivity material to achieve passive cooling of the bifacial PV module. The results show that bifacial PV modules coupled with natural convection hybrid air-fin heat sink cooling method can decrease the maximum and average temperatures in subtropic climate(Dubai) and temperate climate(Harbin). For the bifacial PV module with high thermal conductivity embedded fins in Dubai, the best temperature drops of 13.6 K and 11.9 K can be acquired for the maximum and average temperatures, respectively. The best fin height is 60 mm by considering the structural stability and convenient installation, and the best thermal conductivity of non-embedded or embedded fins is around 200 W/(m K). The power conversion efficiency improvement of 4.4 % can be achieved when high thermal conductivity embedded fins are applied for the bifacial PV module.

A numerical study of phase change material melting enhancement in a horizontal rectangular enclosure with vertical triple fins

In renewable energy systems, energy storage with phase change materials (PCM) is important, but these materials have poor thermal conductivity; therefore, approaches for improving the performance of these storage systems have become required. This research investigates numerically whether fins affect thermal energy storage (TES) units' behavior during phase changes. Three conductive fins at different positions were attached to the heated bottom wall to enhance the PCM melting process. Different dimensionless fin lengths (a/H = 0.25, 0.50, and 0.75) and dimensionless fin positions (b/L = 0.15, 0.25, 0.35, and 0.75) were considered as parameters to investigate their effect on melting rate. The main objective is to detect the best lengths of the fins and the optimum distance between them to achieve the highest storage performance. The enthalpy-based lattice Boltzmann technique is used to solve velocity and temperature fields for simulations. The results from other researchers validate the numerical predictions. It is found that significant enhancement in the heat transfer is shared between thermal conduction and convection at the initial and final stages of melting, respectively. Increasing the ratios fin lengths of a/H from 0.25 to 0.75, the whole melting period is shortened by 15.1%, 40.7%, and 70.1%, respectively. The best compromise positions ratio for short fins at a/H = 0.25 is b/L = 0.48 till the complete melting of PCM, while its b/L = 0.35 when the fine longer than a/H > 0.50.

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 Investigation of the Double Diffusive Convection in 3D Trapezoidal Solar Still Equipped with Conductive Fins

In this paper a numerical investigation on the double diffusive natural convection in a finned solar still is performed using the finite volume method. The 3D vector potential-vorticity formalism is used to eliminate the gradient pressure terms and due to the complex shape of the cavity the blocked-off-region method is adopted. After getting the dimensionless governing equations, they are written in a generalised form then discretised. The effects of the buoyancy ratio, conductivity ratio and Rayleigh number of the flow structure, temperature field and heat and mass transfer are studied. The results show that the increase of conductivity ratio and Rayleigh number leads to an enhancement of the heat and mass transfer.