Effects Of Fin Configurations Research Articles

Investigation on Thermal and Hydraulic Performances in a Printed Circuit Heat Exchanger with Airfoil and Vortex Generating Fins

In this study, the effects of fin configurations and layouts on thermal and hydraulic performances in a printed circuit heat exchangers with supercritical liquefied natural gas as the working fluid are numerically studied, and the overall heat transfer performance is evaluated by the thermal performance factor. Firstly, the effect of three different airfoil configurations, that is, NACA 0024, NACA 0024 with vortex generator, and NACA 0024 with curved vortex generator (CVG) is investigated. The comparative results indicate that NACA 0024 and CVG combined configurations offer the best overall heat transfer performance. Furthermore, the effect of the CVG minimum transverse distance is analyzed in detail. The results show that for a given CVG configuration, the CVG minimum transverse distance should not be too small or too large, so that the longitudinal vortices (LVs) generated will not interact with each other and the LVs’ influences may reach a longer distance. The optimal CVG minimum transverse distance is 1.75 of maximum airfoil thickness. Finally, the effect of CVG attack angle is studied. The results indicate that the optimal CVG attack angle of combined configurations is 45° for improving the overall heat transfer performance, and an optimal CVG and airfoil fin arrangement is suggested.

Effect of fin configuration and orientation of latent heat storage system on the melting and solidification performance

Phase change materials (PCMs) are used to store thermal energy. They possess high specific energy at nearly constant temperatures. The usage of the PCMs is limited due to their very low thermal conductivity, which results in poor heat transfer. To overcome this problem usage of fins is a potential technique. In the current analysis, the surface area of the heat transfer fluid (HTF) tube is increased by radial (R-type), spiral (S-type), and longitudinal (L-type) fins. A 3D numerical analysis of melting and solidification is carried out on R-type, S-type, and L-type shell and tube (S&T) PCM heat exchanger (HX) by considering the inclination effects. Lauric acid is used as PCM. Phase change time, energy ratio, and exergy efficiency are considered to analyze the performance of HXs. MOORA analysis is carried out to select the best HX. It is observed that R-type HX at the vertical position has shown better performance among the selected HXs. Among the considered geometries, the maximum average exergy efficiency is obtained for 45° inclination with R-type HX and minimum for horizontally positioned L-type HX during both melting and solidification. The charging time of the vertically positioned HX, when compared to 45o oriented HX with R type, S type, and L type HX is observed to decrease by 47.5%, 45.7%, and 23%, respectively.

Investigation of the Effect of Fin Configuration and Fin Angle on Thermal Performance of Finned-Tube Heat Exchanger. Experimental Study

Investigation of the Effect of Fin Configuration and Fin Angle on Thermal Performance of Finned-Tube Heat Exchanger. Experimental Study

Experimental and numerical investigations of thermal performance enhancement in a latent heat storage heat exchanger using bifurcated and straight fins

In this paper, the effects of applying straight and bifurcated fin configurations on melting behavior of paraffin inside the shell-and-tube heat exchangers are both experimentally and numerically investigated. Three different fin arrangements for each of the fin configurations were considered: (a) cross arrangement, (b) diagonal cross arrangement and (c) arranged evenly at the lower half of the heat exchanger. The evolution of the melt front was photographed to obtain the instantaneous melt fractions and gain a better insight into the effect of fin configuration on the melting process of phase change material under different Rayleigh and Stefan numbers. The impacts of fin length and thickness on the thermal performance of the heat exchangers were also investigated while the mass of fins for all cases was kept constant. It was found that the bifurcated fin configuration outperforms the straight fin configuration. Also, the fin arrangement showed a significant effect on the melting process. Numerical results revealed that the optimum fin arrangement depends on the fin length which was more pronounced when the fins located at the lower half of the annulus. For charging temperature of 95 °C (Ste = 1.08, Ra = 1.73 × 106), the maximum melting time reductions of bifurcated fin heat exchangers with dimensionless fin lengths of 0.51 and 0.89 mm, compared to those of the straight fin heat exchangers, were 19.5% for the (c)-type fin arrangement and 61.6% for the (b)-type fin arrangement, respectively.

Optimization of fin configurations and layouts in a printed circuit heat exchanger for supercritical liquefied natural gas near the pseudo-critical temperature

In this study, the effects of fin configurations and layouts on thermal and hydraulic performances of printed circuit heat exchangers (PCHEs) with supercritical liquefied natural gas as the working fluid are studied by a numerical method, and the overall heat transfer performance of various parameters is evaluated by the JF factor. Firstly, the effect of four different airfoil configurations, i.e., NACA 0015, NACA 0018, NACA 0021, and NACA 0024, on thermal and hydraulic performances is investigated. The comparative results indicate that NACA 0024 offers the best overall heat transfer performance. Furthermore, the effect of the vortex generator (VG) minimum transverse distance on thermal and hydraulic performances is analyzed in detail. The results show that, for a given VG configuration, the VG minimum transverse distance should not be too small or too large, so that the longitudinal vortices (LVs) generated will not interact with each other and the LVs’ influences may reach a longer distance. The optimal VG minimum transverse distance is 2.0Wa. Finally, the nonuniform segmented heat transfer enhancement mechanism of PCHEs with VG and airfoil fins near the pseudo-critical temperature is explained. The results indicate that the upstream-denser VG and airfoil fins are good choices for improving the overall heat transfer performance, and an optimal VG and airfoil fin arrangement is suggested.

Experimental investigation of n-eicosane based circular pin-fin heat sinks for passive cooling of electronic devices

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 2mm, 3mm and 4mm 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 3mm fin thickness heat sink has best enhancement in operation for TM module controlling temperature of electronic devices.

Numerical simulation of natural convection in annuli with internal fins

The solution for the natural convection in internally finned horizontal annuli is obtained by using a numerical simulation of time-dependent and two-dimensional governing equations. The fins existing in annuli influence the flow pattern, temperature distribution and heat transfer rate. The variations of the fin configuration suppress or accelerate the free convective effects compared to those of the smooth tubes. The effects of fin configuration, number of fins and ratio of annulus gap width to the inner cylinder radius on the fluid flow and heat transfer in annuli are demonstrated by the distribution of the velocity vector, isotherms and streamlines. The governing equations are solved efficiently by using a parallel implementation. The technique is adopted for reduction of the computation cost. The parallelization is performed with the domain decomposition technique and message passing between sub-domains on the basis of the MPI library. The results from parallel computation reveal in consistency with those of the sequential program. Moreover, the speed-up ratio shows linearity with the number of processor.

1813 ハイブリッド型ガス-ガス熱交換器の伝熱特性に関する実験的研究(フィン形状の影響)

1813 ハイブリッド型ガス-ガス熱交換器の伝熱特性に関する実験的研究(フィン形状の影響)

Heat transfer characteristics of a latent heat storage unit with a finned tube. Effects of fin configuration.

Effects of the configuration of a finned tube on the heat transfer characteristics of latent heat storage have been studied experimentally and theoretically. As a result, it has been shown that the performance of the latent heat storage unit is almost the same for finned tubes having the same surface area even if the fin configuration is different. Calculated results of heat fluxes for two types of finned tube have been in good agreement with the experimental values, and the validity of the calculations has been indicated.