Fin Arrangement Research Articles

Investigation of the geometrical structure of louvered fins in fin-tube heat exchangers for determining the minimum distance of the headers

The effects of the geometrical arrangement of fins on the streamlines, pressure drop and heat transfer in louvered fin and tube compact heat exchangers were numerically studied using the e-NTU method. The effects of pitch variation, angle, the number of louvers, and flow redirection location in a series of the fins, as well as non-louvered inlet and exit fin length were investigated. Also, the effects of the aligned, non-aligned, positive, and negative louver angles were examined. The simulation results show that the redirection of streamlines depends on the louver angle and the distance of flow re-direction location from the inlet edge of the fin and not on the non-louvered inlet and exit fin lengths, fin pitch, or the number of louvers. Moreover, based on the obtained results, the angle relative to horizon of suction or blowing direction does not affect heat exchanger efficiency. In contrast, the alignment of suction or blowing directions in multiple fins has a significant impact on heat exchanger performance, increasing the amount of heat transfer by 40 %. An analytical equation has been proposed for estimating the maximum height of flow deviation based on two effective parameters of louver angle and the distance of flow redirection location from the inlet edge of the fin.

A Comparison of the Performance of Constant and Dual Height Pin Fins in Phase Change Material Cooling Technique

Abstract This experimental study explores the passive cooling of electronic devices using phase change materials (PCM). Pin fin configurations made of aluminum are considered as thermal conductive enhancers and eicosane as the PCM for the study. The experiment considers four different heat sinks, with 40 and 56 numbers of pin fins. For the same number of pin fin, dual and constant height fin arrangements are study. The volume fractions of TCEs are 9%, 11%, 13%, and 16%. Apart from these heat sinks, a heat sink with no fin (blank heat sink) is considered for baseline comparison. Five different heat fluxes are considered (ranging from 1.17 kW/m2 to 2.35 kW/m2). The effect of number of fins, type of fins, and volumes of PCM has been reviewed. It has been observed that the introduction of fins enhances the heat transfer. An elongation in operational time is achieved in the case of dual height heat sinks compared to constant height heat sink filled with PCM. All the experiments are performed in a temperature-controlled room to avoid environment fluctuation.

Thermo-Hydraulic Performance of Square Micro Pin Fins under Forced Convection

Thermal management of the new generation’s high performance electronic and mechanical devices is becoming important due to their miniaturization. Conventionally, the plate fin arrangement is widely used for removal of dissipated heat but, their effectiveness is not up to mark. Among different options, the most attractive and efficient alternative for overcoming this problem is micro pin fin heat sink. This paper presents the experimental investigation of square micro-pin fins heat sink for identifying the most suitable pin fin geometry for heat removal applications under forced convection. Twenty five square micro pin fin heat sinks were tested for three different heat load and Reynolds number. The results show that for large fin height lower thermal resistance was observed at the cost of large pressure drop. The dimensionless heat transfer coefficient increases with fin height and Reynolds number while it decreases with increasing fin spacing. The improvement in micro pin fin efficiency were observed by about 2 to 9% owing to presence of fins on the impingement surface, flow mixing, disruption of the boundary layers, and augmentation of turbulent transport.

Performance analysis of arc rib fin embedded in a solar air heater

A thermal model is developed for analysing the influences of arc rib fin arrangement and length of absorber plate on the heat transfer characteristics of a solar air heater. The arc rib fin arrangement is designed by varying the fin relative roughness height ratio (e/De) in the absorber plate. Solar air heater with fixed arc rib fin configuration with e/De (0.0422) and variable arc rib fin configuration with two different relative roughness height ratios of e/De (0.0422 and 0.0541) are modelled. The influence of absorber plate length (1 and 2 m) on the solar air heater performance is compared with the configurations mentioned above at various mass flow rates of air (0.02 kgs−1 to 0.06 kgs−1). The outlet air temperature of solar air heater, mean absorber plate temperature, heat transfer characteristics (Nusselt number and frictional factor), pressure drop, thermo-hydraulic performance parameter, efficiencies (thermal, effective, and exergy), collector efficiency factor, and collector heat removal factor are predicted at different air flow rates. The variable arc rib fin arrangement in the solar air heater leads to maximum utilization of available solar energy from the absorber plate, and reported maximum outlet air temperature and lower mean absorber plate temperature when compared to fixed arc rib fin arrangement and smooth duct. Further, the variable arc rib fin arrangement has better heat transfer and thermo-hydraulic characteristics than the fixed arc rib fin arrangement and smooth duct. Thus implementation of the variable arc rib fin arrangement will significantly enhance the overall performance of the solar air heater.

A Review on Analysis of Heat Transfer Coefficient in Internal Rib Tube

The rate of heat transfer is increased by a fin arrangement applied to the rectangular duct. In order to save energy, many industrial heat exchange devices use various techniques to improve heat transfer, such as: B. fins, dimples, vortex chamber and ribbed tabs. The most common technique used to improve heat transfer is to add fins to the flow channel. The ribs are of simple construction and are widely used in many industries. Turbulent kinetic energy generation increases turbulent heat transfer in the duct due to flow disturbances caused by fin arrangements. The shape of the fin plays an important role in improving heat transfer as it affects the formation of bubble separation behind the fin and the amount of turbulent kinetic energy generated.

Analysis of heat transfer enhancement in microchannel by varying the height of pin fins at upstream and downstream region

In this study, a numerical analysis of a microchannel with the different configuration of varying height of pin fins entrenched at the bottom of the channel base wall has been carried out. Five different configurations of pin fins arrangement which are considered in this study are, Case 1(Full length fins in complete microchannel), Case 2(Full length fins at the upstream), Case 3(Full length fins at the downstream), Case 4(Full length fin at the center of microchannel), Case 5(Full length fins at the inlet and exit of microchannel) and the results of these five cases are compared with the plain rectangular microchannel. In this investigation, deionized ultra-filtered water is used and Reynold’s number is ranging from 150 to 350. Results reveals that the highest Nusselt number is achieved by case 2 at a lesser value of Reynold’s number while by case 5 at higher Reynold’s number and the lowest pressure drop is occurring in case 4. The overall thermal performance of case 2 beats the corresponding cases.

Geometrical variation in receiver tube of SEGS LS-2 parabolic trough collector (PTC) based on heat flux distribution to improve the thermal performance

Heat flux (HF) distribution around the receiver tube of parabolic trough collectors (PTC) has a crucial effect on their outlet temperature (To) and thermal efficiency (ηth). Since its receiver tube is as a heat exchanger, the higher amounts of ηthcan be achieved by changing the geometry of the receiver tube. In previous researches, the geometrical variations were made in the internal geometry of the receiving tube, such as the use of corrugated paths, the installation of fins, using porous media, using twisted tape, etc. In this work, changes are simultaneously made in the internal and external geometry of the receiving tube, which is for the first time based on the model of HF distribution around the receiver tube. These changes include usVηing and moving the receiver's central plug, and creating concavities on the receiver tube to augment the contact surface of the wall with the internal working fluid. These concavities are created in regions of the tube that have a higher heat transfer to increase the heat transfer rate as a fin. In order to generate various HFs around the receiver tube and consequently create different arrangements of fins, two types of PTCs have been used in this research. To compare the improvement of each case-studies rather than smooth case, two indices of efficiency-based (VfNu) and two-objective evaluation () are defined. Finally the results show that, in view point of Vη index, PTC with three-piece reflector and also with the central plug as well as the big fins can give the optimum results than the other case-studies. On the other hand, considering the index of VfNu, the conventional PTC with E.F = 2/3 and the big fins can give the optimum results.

Study of the performance of multiple v-type fin arrangements as an enhancement of natural heat transfer from a vertical surface

Thermal influence on home appliances, devices and other engineering systems is so high that it causes a system failure. The dominant mode of heat transfer through these systems is the natural heat transfer. As the value of heat transfer coefficient is low, an extension in the heat transfer area becomes essential. The extension is merely to add fins with different shapes and configurations depends on the geometry of systems and space available. One of these configurations is the V type fin array. A testbed was built using two different configurations of fin array. The first array looks like the letter “V” with two discrete parts and the other array is the upset of the letter “V”. The array consists of two columns and five rows separated by a certain distance. The variable heat fluxes were achieved by changing the voltage of three heating elements fixed to the backside of the testbed. Seven thermocouples were fixed at different positions on the testbed and the experiment was run to calculate the natural heat convection through the testbed. The configuration with upset V shape fin shows better performance because it allows the air to flow faster through the middle passage separating the fin array.

Review on Heat Transfer Enhancement by Louvered Fin

The heat transfer enhancement is recycled in many engineering uses such as heat exchangers, refrigeration and air conditioning structures, chemical apparatuses, and automobile radiators. Hence many enhancing extended fin patterns are developed and used. In multi louvered fin, in this segment for multi-row fin and tube heat exchanger, an increase in heat transfer enhancement is found 58% for ReH = 350. When the Reynolds number is 1075, the temperature gradient is more distinct for greater louver angle that is the higher heat transfer enhanced for large louver angle. For variable louver angle heat exchanger, the maximum heat transfer improvement achieved by 118% Reynolds number at 1075. In the vortex generator for the delta winglet vortex generator, the extreme enhancement of heat transfer increased to 16% compared to the baseline geometry (at ReDh = 600). For a compact louvered heat exchanger, the results showed that a regular arrangement of louvered fins gives a 9.3% heat transfer improvement. In multi-region louver fins and flat tubes heat exchanger, the louver fin with 4 regions and the louver fin with 6 regions are far better than the conventional fin in overall performance. At the same time, the louver fin with 6 regions is also better than the louver fin with 4-region. The available work is in experimental form as well as numerical form performed by computational fluid dynamics.

Thermal Performance of Flat Plate Solar Collectors for Humid and Unpredicted Weather using Air Properties and Energy Method

Devising technologies to make use of renewable energy such as solar energy is very innovative and progressive sincetapping energy from a free source is cost effective in the long-term and totally ecologically friendly. The main aim ofsolar drying of crops is to preserve them by removing the excess moisture that will cause their deterioration in orderto improve their shelf life. Solar drying though found to be a mature, cost-effective and an efficient method ofdrying especially crops, it has not been widely deployed for crop drying both at the commercial and industrial levelin Ghana. The purpose of this research is to produce a solar heat collector for space heating using cheap andavailable materials and also to demonstrate the importance of incorporating obstacle/fins on plates to improve theefficiency of solar collectors. This study investigates the effect of increased air contact area of various configurationon the efficiency of solar air heaters. Nine different absorber plates (with and without fins) were considered by thisresearch in an experimental study to select the best design that will be suitable for absorbing or providing a highfraction of heat for conditioning humid atmospheric air (lowest relative humidity of the collector air). The bestdesigns of this study had an efficiency between 58% to 72% and maximum absorber temperatures above 80oC,collector air temperature above 70oC and collector air relative humidity below 20% while the worst design had anefficiency between 35% and 50%, collector air temperature bellow 45oC and the lowest collector air relativehumidity of 26%. The findings of this research have revealed that increasing the contact area of the air current orcirculation and the shapes of the fins attached to flat absorber plates increase their air contact areas and affect thethermal efficiency of the solar collectors. Also, it has revealed that the arrangement of fins contributes positively tothe efficiency of solar collectors.
 Citation: Felix Uba, Eric Osei Essandoh, Gilbert Ayine Okolo, Charles Nunya Dzikunu. Thermal Performance of Flat PlateSolar Collectors for Humid and Unpredicted Weather using Air Properties and Energy Method, 2020; 5(4): 30-49.
 Received: September 17, 2020Accepted: December 31, 2020

Finite element design and thermal analysis of an induction motor used for a hydraulic pumping system

In our day-to-day applications, we are using so many electrical motors. In those, Induction motor (IM) is the most used one in domestic and industrial applications. Mainly the Induction motors are used for water hydraulic pumping system in domestic applications. In Agriculture also, it plays a significant role. The induction motor needs to run for a very long time in such circumstances. It is very significant from the perspective of agricultural production. Mostly because of this continuous operation, the motor tends to get overheated. It will damage the motor if the condition persists. Therefore, the cooling of the induction motor becomes mandatory. For efficient cooling, the fin arrangement is provided over the induction motor. Thus, by adding fins, the heat dissipation surface area for convective heat transfer gets increased, and through natural convection, the motor temperature gets reduced. In the present work, the thermal analysis of induction motor is investigated by means of varying the total number and height of the fins. In this regard, the induction motor used for pumping system is designed by using the Flux 2D software package. And also, thermal analysis is carried out by using Finite element software packages Motor-CAD and ANSYS.

FLUID FLOW AND HEAT TRANSFER BEHAVIOR IN DISTINCT ARRAY OF STEPPED MICRO-PIN FIN HEAT SINK

In this paper, numerical analysis has been performed on micro-pin fin heat sinks with novel arrangements of the fins. Varying the fin height in an array of two, three, and four fins evolves stepped-type pin fin heat sink. Geometry selection of all seven configurations of the heat sinks is made on the basis of equal footprint area as well as net convective surface area. Single-phase liquid water has been used as a cooling medium where inlet Reynolds number (Re) varied from 200-600. Comparative numerical results are presented through the illustration of temperature distribution, Nusselt number (Nu), pressure drop, velocity contour, and thermal performance factor. Estimated findings clearly indicate that the overall performance of the stepped configurations is better than uniform fin height. Moreover, arrays of increasing fin heights facilitate favorable flow behavior compared to decreasing fin height; consequently, they support higher heat transfer rate from the heat sink. Among the stepped heat sinks, THSI (three-stepped increasing) configuration exhibits superior performance due to distinct coolant flow and favorable heat dissipation circumstances originated by constructive fin arrangements. Similarly, the thermal performance factor of THSI is found to be consistently higher compared to all other heat sinks.

Effects of pin fin arrangement its heat transfer characteristics on performance of heat sink

Abstract The use of pin fins is to increase the rate of heat transfer to the environment by increasing the convection. The amount of heat transfer is determined by the amount of conduction, convection, radiation. If the “temperature gradient between the object increases” then the heat transfer rate also increases. The main aim of our project is to increase the heat transfer rate at constant Reynolds number by comparing two types of fin geometry with dimples. The 3D model is fabricated in CATIA software. The experimental testing is carried out and then the result & conclusion is drawn.

Performance of displaced fin heatsink in natural convection subject to upward and downward arrangement

In this study, a heat sink with a displaced fin arrangement is proposed to enhance the thermal performance in natural convection. To demonstrate the competence of the proposed heat sink design, an experimental investigation was carried out for the upward and downward configurations for the heat flux range of 30–470 Wm-2. The experimental results suggest that the proposed heat sink with the fin displacement distance of 20 mm can reduce the total thermal resistance by 11% and 14% for the upward and downward configurations, respectively. The parametric study was conducted with the Definitive Screening Designs (DSDs) method, and it suggested thirteen optimized test conditions. The outcome of the parametric study implies that the fin spacing plays a vital role in determining the heat sink performance, followed by the fin height and fin length; and the effect of heat flux is insignificant. For the thirteen test conditions suggested by the DSDs method, the numerical investigation was conducted. The numerical results show that for the same volume, when compared to the regular rectangular heat sink the proposed heat sink can provide an 11% performance enhancement with a 28.7% reduction in mass.

Experimental study of flow boiling performance of open-ring pin fin microchannels

A type of open-ring pin fin microchannels (ORPFM) was proposed and developed for advanced microchannel heat sinks. They consist of an internal cavity for bubble nucleation and two inner small and outside large rings with separated and converged flow passages. Two arrangements of open-ring pin fins, inline and staggered ones, were prepared and compared for optimization. Flow boiling experiments were performed to assess the two-phase boiling performance of both inline and staggered ORPFM. Tests were conducted using subcooled deionized water with an inlet subcooling of 10°C and mass fluxes of 200 kg/m2·s and 300 kg/m2·s. Two-phase boiling heat transfer performance, pressure drop and two-phase flow instabilities of the ORPFM were systematically explored. Experimental results indicated that both inline and staggered ORPFM samples presented a small wall superheat of 1-2°C for onset of nucleate boiling (ONB). Nucleate boiling, both nucleate boiling and thin film evaporation, and convective boiling in turn dominated with increasing heat flux and vapor quality for ORPFM. The inline ORPFM generally presented a 10% to 80% augmentation in boiling heat transfer at moderate and high heat fluxes, a 2%-20% smaller pressure drop, and more stable flow boiling process with a mitigation of two-phase flow instabilities than the staggered one. Therefore, the inline ORPFM seemed to be more favorable for high heat flux dissipation of advanced microchannel heat sinks.

Influence of fin orientation on the natural convection of aqueous-based nano-encapsulated PCMs in a heat exchanger equipped with wing-like fins

The heat transfer enhancement in pin-fin heat exchangers is achieved by fluid mixing, disruption of the thermal-viscous boundary and the extension of the effective surface area for maximum heat exchange. The orientation and configuration of the fins are among the prime factors influencing the performance of these heat exchangers. Therefore, the present study investigates the combined influences of fin angle (0≤ζ≤270), arrangement and position of the wing-like fins on the natural convection of aqueous-based nano-encapsulated phase change material (PCM) in a fin heat exchanger. The analysis is performed for Rayleigh and Stefan numbers of 1e3-1e5 and 0.2 respectively by considering the PCM concentration of 0.05. The flow is assumed to be laminar, incompressible and Newtonian. The results demonstrate that the vertical alignment of the fins contributes to the augmentation of the thermal performance compared to the horizontally arranged fins. At the larger Rayleigh number, the mode of heat transfer is predominantly convective and thermal performance slightly deteriorates due to the blockage caused by adjacent fins. For low Rayleigh number, the conduction is the primary mode of heat transfer between the source and sink fins. This phenomenon is crucial to determine the heat exchanger thermal performance.

Performance evaluation of cascaded storage system with multiple phase change materials

The charging enhancement of latent heat thermal energy storage system is of great significance for the efficient transfer of non-uniform thermal sources. In order to solve the problem of long charging time caused by the low thermal conductivity of phase change materials (PCMs), multiple PCMs - uneven fins combination as a compound enhancement approach was proposed to improve thermal storage rate. The transient heat transfer and melting process of PCMs was numerically studied by the finite volume method and enthalpy-porosity method. Firstly, the filling ratio of high melting point PCM to high melting point PCM was optimized as 60%: 40%. Under the optimal ratio, the charging time was reduced by 29% and the thermal storage rate was increased by 9%. Then, the effect of natural convection on multiple PCMs melting characteristics was analyzed. Finally, the thermal storage performance of multiple PCMs - uneven fins combination was investigated. The results indicated that the reasonable fin arrangement (upper dense - lower sparse fins) strengthens the local convection and improves the melting uniformity, which reduces the melting time by 16% and increases the thermal storage rate by 7%. Therefore, multiple PCMs - uneven fins combination can obviously reduce the charging time and increase the thermal storage capacity, which contributes to promote efficient utilization of fluctuating thermal energy.

Melting process of nanoparticle enhanced PCM through storage cylinder incorporating fins

This paper discusses how the arrangement of fins can affect the charging process. Mixture of paraffin and copper oxide nanomaterial has been utilized. Several configurations of fins with various position, thickness and length were discussed. Volume fraction of NEPCM in domain is constant, thus reducing melting time is criterion for good efficiency. Outputs reveal that with incorporating fins in both sides, melting process becomes more uniform. Lower melting time with using longer fins is a result of more effective buoyancy forces by dividing the whole domain into smaller blocks. Using fins over both inner and outer pipes shorten the melting time. The main purpose of current modeling is finding the optimized style of fins to gain the highest performance. Nice accommodation of outputs with empirical previous data indicates the verification of code.

A Parametric Study of Wind Pressure Distribution on Façades Using Computational Fluid Dynamics

This paper uses Computational Fluid Dynamics (CFD) to determine wind pressures on façades for the purpose of efficient design of these elements. An outstand fin arrangement was modeled where local brackets are used to protrude the fins from the building. A parametric study, for both changes in the length of the bracket and the fin, was derived from CFD simulations with 1-in-50-year storm conditions adopted throughout. Further simulations are performed for revised wind directions that ensure all fins are equally exposed to oncoming winds. In total, 15 models are created to act as a representative sample of the total number of possible configurations. Peak values for pressure are used to calculate forces and moments on the fins. These wind loading results were then used to interpolate the values for the remaining façade geometries. From interpreting the trends that are apparent in the relationship of fin size and bracket length to efficient loading, a set of design criteria is established. The optimal façade design is defined, based on placing equal importance onto minimizing the force along the fin’s length and the moment acting at the fin-bracket connection. The performance of some façade elements is shown to worsen the effects of the wind, relative to other designs, with the potential for very negative consequences. Wind direction is shown to have a significant effect on loading, with the magnitude of wind pressures reduced considerably for the worst affected fin, if the sheltering effect is absent between the fins.

Evaluation and optimization of melting performance in a horizontal thermal energy storage unit with non-uniform fins

The shell and tube latent heat thermal storage systems are widely used in the storage and utilization of fluctuating thermal energy resources due to high thermal storage density, constant discharge temperature, simple processing and low cost. Adding fins to phase change materials is an effective method to expand the heat transfer area and improve the heat transfer rate. However, the obvious thermal stratification phenomenon and slow melting rate problem are exited in the horizontal latent heat thermal energy storage system. In order to improve the melting rate and uniformity, different non-uniform fin arrangements were designed and investigated in this study to improve the thermal performance. A numerical model of the melting characteristics of phase change materials was established and validated by the experimental results in the literature. The effects of fin arrangement, angle and length on the thermal performance of the melting process were quantitatively evaluated by analyzing the temperature field, velocity field and liquid fraction distribution before and after melting. Results indicated that when the fin angle α=25° and the fin length L=40 mm, the melting time is decreased by 83.9% and thermal storage density is improved by 466%, which meant that the lower fin arrangement realized the synergistic enhancement of natural convection and heat conduction. On this basis, the effect of the heat transfer fluid temperature on the thermal storage performance of the optimal scheme was further studied. The non-uniform fins design proposed in this study can provide theoretical support for the design method of thermal storage system, and contribute to the efficient utilization of intermittent thermal energy resources such as solar energy and industrial waste heat.