How to measure the effectiveness of the fin?
The fin efficiency is defined as the ratio of the heat transfer to the fin to the heat transfer to an ideal fin. ηth= qfin hAfin(Tb−T∞), Tf=T∞,and Afin=2Ac+Atip (Square and Recatngular ) 1.35 Atip=t×W Fig. 2.4. Rectangular Fin For cylindrical: Afin=πDL+ πD2 4 From Eq.(1.29 ), the heat transfer to the fin is at x =0 yields
What are fins used for?
In this work the performance of pin-fin heat sinks having an unconventional fin profile is compared with the use of cylindrical fins. The fin profile is a …
What is the purpose of a fin in a heat exchanger?
of the fin NTU f is the number of heat transfer units for the fin: NTU f =Ahm& a c p (6) where A and m& a c p are the fin surface area and heat capacity of fluid side contacted with fin. The fin temperature shows one-dimensional distribution and the theoretical fin efficiency was the same as the Q/Qmax. 0.0 0.2 0.4 0.6 0.8 1.0 x/L 0.0 0.2 0.4 0 ...
How do cooling fins work?
Sep 04, 2011 · Steady heat transfer through a pin fin is studied. Thermal conductivity, heat transfer coefficient, and the source or sink term are assumed to be temperature dependent. In the model considered, the source or sink term is given as an arbitrary function. We employ symmetry techniques to determine forms of the source or sink term for which the extra Lie point …
What are the assumptions made in deriving an expression for finding temperature distribution along a circular fin?
The following assumptions are made for the analysis of heat flow through the fin: Steady state conduction. No heat generation within the fin. Uniform heat transfer coefficient (h) over the entire surface of the fin.
What are pin fins used for?
Pin fins are used to increase heat transfer from heated surfaces to air. Industrial experience has shown that for the same surface area, pin fins can transfer considerably more energy than straight fins. The analysis of a single pin fin is well known.
How does a fins enhance heat transfer at a surface?
Fins are extensions on exterior surfaces of objects that increase the rate of heat transfer to or from the object by increasing convection. This is achieved by increasing the surface area of the body, which in turn increases the heat transfer rate by a sufficient degree.
At which of the given conditions will the rate of heat transfer of a rectangular fin increase?
If effectiveness is greater than one then only added fin will increase the heat transfer rate otherwise it will have no meaning of adding it to the surface. Now if the value of h A k p < 1 then the effectiveness will be greater than one, which ultimately will increase the heat transfer.
What are the advantages of pin fin?
In particular, the pin fin heat sink geometry is designed to provide increased surface area for heat transfer, low thermal resistance from base to fins at high airflow (200-plus LFM), and work in environments where the direction of airflow is ambiguous.Aug 22, 2017
What is pin fin experiment?
Pin Fin Apparatus: This setup is designed to study the heat transfer in a pin fin. It consists of cylindrical fin fitted to the base in rectangular duct. A blower is provided on one side of duct to conduct experiments under forced convection heat transfer mode.Sep 13, 2021
What is the purpose of using fins in heat transfer?
Application of fins: Fins are the extended bodies attached to accelerate heat transfer rate by increasing the area exposed to convective heat transfer.
Why fins are provided on the surface of the cylinder?
Abstract. An air cooled motorcycle engine release the heat to the atmosphere through the mode of forced convection, fins are provided on the outer surface of the cylinder block of the engine. The heat transfer is depends upon the velocity of the air, ambient temperature, geometry of the fin and the surface of the fin.
How does a fin enhance heat transfer at the surface and state the mode of heat transfer through a fin?
Fins enhance heat transfer from a surface by increasing heat transfer surface area for convection heat transfer. However, adding too many fins on a surface can suffocate the fluid and retard convection, and thus it may cause the overall heat transfer coefficient and heat transfer to decrease.
What is the rate of heat transfer from the fin in case of fin insulated at the tip?
Explanation: The fin is of finite length with the tip insulated and so no heat is transferred from the tip.
What is fin efficiency and fin effectiveness derive the relation of rate of heat transfer for the infinite long fin?
ηfin=h.P.K.Ach.As. Effectiveness of fin (εfin): It is defined as the ratio of the actual heat transfer that takes place from the fin to the heat that would be dissipated from the same surface area without fin. By above definition ε for infinite length fin is given by εfin=h.P.K.Ac(ts-ta)h.Ac(ts-ta) εfin=P.Kh.Ac.
What is fin effectiveness and fin efficiency?
2 Fin Efficiency and Surface Effectiveness. Fin efficiency is defined as the ratio of actual heat flow of the fin to that which would be obtained with a fin of constant temperature uniformly equal to the base surface temperature, that is, one with infinite thermal conductivity.
What are the benefits of using a strip fin heat sink?
Results show that strip fins provide another effective means of enhancing heat transfer , especially when staggered arrangements of strip fins are used. A detailed parameter investigation demonstrates that perforating the strip fins provide additional improvements in terms of enhanced heat transfer, together with reduced pressure loss and heat sink mass. Results are also given which show that, for practical applications in micro-electronics cooling, perforated SFHSs offer important benefits as a means of achieving smaller processor temperatures for reduced mechanical power consumption.
What are the characteristics of a PEM fuel cell?
Some of those features are low start-up, high power density, high efficiency and remote applications . In the present study, a numerical investigation was conducted to analyse the flow field and reactant gas distribution in a PEM fuel cell channel with transversely inserted pin fins in the channel flow aimed at improving reactant gas distribution. A fin configuration of small hydraulic diameter was employed to minimise the additional pressure drop. The influence of the pin fin parameters, the flow Reynolds number, the gas diffusion layer (GDL) porosity on the reactant gas transport and the pressure drop across the channel length were explored. The parameters examined were optimized using a mathematical optimization code integrated with a commercial computational fluid dynamics code. The results obtained indicate that a pin fin insert in the channel flow considerably improves fuel cell performance and that optimal pin fin geometries exist for minimized pressure drop along the fuel channel for the fuel cell model considered. The results obtained provide a novel approach for improving the design of fuel cells for optimal performance.
What are microchannels used for?
Microchannels have been studied extensively for a variety of heat transfer applications including electronic cooling. Many configurations of microchannels have been studied and compared for their effectiveness in terms of heat removal. Recently, the use of staggered pins in microchannels has gained considerable traction since they can promote internal flow fluctuations that enhance internal heat transfer. Furthermore, staggered pins in microchannels have shown higher heat removal characteristics because of the continuous breaking and formation of the heat transfer fluid boundary layer. However, they also exhibit higher pressure drop because the pins act as flow obstructions. This paper presents numerical results of two characteristic staggered pins (square and circular) in microchannels. The heat transfer performance of a single phase fluid in microchannels with staggered pins, and the corresponding pressure drop characteristics are presented. Furthermore, a phase change material (PCM) fluid was also considered by implementing the effective specific heat capacity model approach to account for the corresponding phase change process of PCM fluid. Comparisons of the heat transfer characteristics of single phase fluid and PCM fluid are presented for two different pin geometries and three different Reynolds numbers. Circular pins were found to be more effective in terms of heat transfer by exhibiting higher Nusselt number. Microchannels with circular pins were also found to have lower pressure drop compared to the square pin microchannels.
What is PCM in electronics?
Efficient thermal management (TM) based on phase change material (PCM) is adopted for the cooling of portable electronic devices. PCM namely n-eicosane is employed to absorb thermal energy released by such electronics. Four different configurations of circular pin-fin heat sinks with fin thickness of 2 mm, 3 mm and 4 mm including a no fin heat sink (used as a reference heat sink) were adopted. Pin-fins were made of aluminum due to light weight and good thermal conductivity to act as a thermal conductivity enhancers (TCEs). Pin-fin heat sinks of constant (9%) volume fraction of TCE are filled with four volumetric fractions of PCM to explore the best amount of PCM volume. A wide range of heat flux is provided at the heat sink base and the effect of fin configuration, PCM volume, latent heat phase, power densities, thermal capacity and thermal conductance are reported in this study. Three different critical set point temperatures (SPTs) are selected for this investigation. Enhancement ratios are reported against various PCM fractions to illustrate the thermal performance for passive cooling. The results show that 3 mm fin thickness heat sink has best enhancement in operation for TM module controlling temperature of electronic devices.
What is heat dissipation?
— Heat dissipation techniques are the prime concern to remove the waste heat produced by Electronic Devices, to keep them within permissible operating temperature limits. Heat dissipation techniques include heat sinks, fans for air cooling, and other forms of cooling such as liquid cooling. Heat produced by electronic devices and circuitry must be dissipated to improve reliability and prevent premature failure. Integrated circuits such as CPUs, chipset, graphic cards, and hard disk drives are susceptible to temporary malfunction or permanent failure if overheated. As a result, efficient cooling of electronic devices remains a challenge in thermal engineering. The objective of this paper is to present an Optimal Heat Sink for efficient cooling of electronic devices. The choice of an optimal heat sink depends on a number of geometric parameters such as fin height, fin length, fin thickness, number of fins, base plate thickness, space between fins, fin shape or profile, material etc. Therefore for an optimal heat sink design, initial studies on the fluid flow and heat transfer characteristics of a standard pin fin, splayed pin fin and Hybrid pin fin heat sinks have been carried through CFD modelling and simulations. It is observed from the results that optimum cooling is achieved by splayed & hybrid pin fin heat sinks. These heat sink designs promises to keep electronic circuits 20 to 40% cooler than standard pin-fin heat sinks.