Balaram Kundu

A decomposition analysis on convecting–radiating rectangular plate fins for variable thermal conductivity and heat transfer coefficient

Abstract The present study concentrates to make a complete thermal analysis on a rectangular fin with its primary surface by taking into consideration of radiation heat exchange with the surrounding along with the convective mode of heat transfer. The one side of the primary surface is heated by a fluid with high temperature which may be required to dissipate heat quickly by a fin array system. To analyze an actual case study, the thermal conductivity of the fin material and convective heat transfer coefficient over the surface are treated as a variable and they are as a function of the local fin surface temperature. With the aforementioned condition, the energy equations for both the fin and primary surface become nonlinear. The decomposition method is suggested to solve these highly nonlinear equations to obtain a closed form temperature distribution. The result of temperature distribution determined by the present analysis is compared with that of the numerical values. With the adaptation of the simplified case, the present method is also compared with the exactly closed form results. From both of these comparisons, an exact matching of results is found. The fin performances, namely, fin efficiency, surface efficiency and augmentation factor are evaluated for a wide range of thermogeometric parameters.

Approximate Analytical Method for Porous Stepped Fins with Temperature-Dependent Heat Transfer Parameters

This work presents the thermal investigation of a porous stepped fin made from different ceramic porous materials (Al and SiC) having temperature-dependent internal heat generation. The fin is dissipating heat to the environment by means of convection and radiation modes of heat transfer, which are further considered to be temperature dependent. The approximate analytical Adomian decomposing method is used to solve this nonlinear problem along with the Newton–Raphson method. The results obtained using the Adomian decomposing method are compared with relevant results available in literature. The effect of various thermophysical parameters on the thermal behavior of the fin is critically analyzed. An optimization study to maximize the heat transfer rate for a constant material volume has been also conducted. The performance of the porous stepped fin is compared with a porous straight fin and solid stepped fin, which proves that the porous stepped fin is a better alternative.

Exact analysis for propagation of heat in a biological tissue subject to different surface conditions for therapeutic applications

Temperature response in skin tissue for therapeutic conditions.Thermal behavior in a skin tissue subject to various surface heating.Temperature response for Fourier and non-Fourier heat conduction.Analytical determination based on separation of variables.Non-Fourier temperature response has significance on boundary conditions.A greater temperature response from isothermal heating. The thermal therapy to kill cancereous cells is gradually increasing due to no side effect for the treatment. For this therapeutic application, different boundary conditions can be selected to establish the effective heating. In the present study, the separation of variables was used to determine the exact expression for temperature response in a biological tissue under Fourier and non-Fourier heat conduction subject to a therapeutic application. As the thermal therapy is dependent on the surface conditions, isothermal, isoflux, and convective-radiative boundary conditions are taken in the present study. Depending upon the inner core condition, five different boundary conditions were adopted to show the temperature response in a tissue. For every case study, the temperature response was explicitly derived. From the results, it can be highlighted that the temperature distribution in a thermal therapy is a strong function of Fourier number F, Vernetto number Ve, and dimensionless blood flow parameter β. However, the temperature is also strong function of the boundary condition applied to the surface and it is also dependent on the inner core condition. The average temperature response was plotted as a function Fourier number and biological parameters, and is always a sinusoidal nature for a lower value of Fourier number. The ripple of sinusoidal curves is dependent on the therapeutic boundary condition applied.

Optimized Envelope Shape of Wet Fins for Nonlinear Heat and Mass Transport

This study presents an analysis for establishing a method to determine an optimum profile of a fin by minimizing its volume for a given heat transfer duty under wet environments with variable thermal conductivity and heat transfer coefficient. A polynomial relationship between the humidity ratio and temperature for mass transfer is employed for predicting its energy transfer accurately. Both fully and partially wet surfaces were investigated over a wide range of thermopsychrometric parameters according to the suitability of any application. The optimality criteria were derived as a function of temperature-dependent parameters, and optimization was carried out by minimizing the fin volume for a constrained heat transfer rate and design constants. From the result, it can be highlighted that the minimum envelope shape of wet fins is a strong function with the heat transfer coefficient. However, the thermal conductivity effect on the optimized fin shape shows marginally.

The Influence of Collector Fluid Inlet Temperature on the Performance of a Solar-Assisted Absorption System Using Step-Finned Flat-Plate Collector

In the present work, an extensive analysis is developed for an evaluation of the thermal performance of a solar-powered H2O/LiBr absorption cooling system using a step-fin flat-plate collector (SFC). The performance parameters, namely, collector efficiency factor, heat removal factor, and collector efficiency, for the SFC is derived. A system simulation model has been developed to analyze the system performance—that is, to identify an operating criterion as a function of the collector fluid inlet temperature (T FI). It has been observed from the results that the performance of the system depends strongly on T FI. Simulation results show that the system operates optimally (maximum coefficient of performance) at an optimal T FI. When the system runs at this optimal value of T FI, minimum collector material is required. Thus, when using SFC in place of a rectangular-fin flat-collector, thirty-five percent or more collector material can be saved. However, it has been observed that the effect of thermal conductivity on the plate volume of SFC has a marginal effect.

Performance Analysis of Plate Fins Circumscribing Elliptic Tubes

The thermal performance of rectangular plate fins circumscribing elliptic tubes is presented in this paper. Based on the assumption of uniform convective heat transfer the two-dimensional conduction equation has been formulated, and the solution has been obtained through the finite element method. Performance of rectangular plate fins for both inline and staggered arrangement of tubes has been investigated for a variation of geometric and thermo-geometric parameters. The necessity of optimizing the fin geometry for a given fin surface area has also been highlighted.

Prediction of Heat Generation in a Porous Fin from Surface Temperature

The present paper demonstrates a nondestructive inverse methodology aimed at estimating the volumetric rate of internal heat generation within a porous fin using the golden section search method (GSSM) algorithm. Distinct from previously reported studies, the present study considers the nonlinear dependency of the heat generation on the temperature in the inverse solution in addition to accounting for all temperature-dependent heat dissipation modes. Using simulated local temperature distribution, an inverse problem is solved using an implicit fourth-order Runge–Kutta procedure in conjunction with the GSSM algorithm. A case study of Inconel is demonstrated with numerical examples. The influence of random measurement errors is also studied. For uncontaminated temperature data, an exact estimation of the internal heat generation rate is accomplished, whereas, even with noisy data, satisfactory estimation of the heat generation rate is also realized as revealed by the temperature reconstructions.

Unique Analysis for Cascaded Rectangular-Triangular Fins with Convection-Radiation Transport

A double-differential transform method has been used to analyze a cascaded rectangular–triangular fin losing heat by simultaneous convection and radiation to its surroundings. The base of the fin is heated by convection by a hot fluid at a uniform temperature. The thermal conductivity of the fin material assumed to be a linear function of temperature. An exact analytical solution is developed for a pure convection cascaded rectangular–triangular fin of constant thermal conductivity. Results are presented for the temperature distribution for a range of dimensionless parameters governing the problem. Both single- and two-material cascaded rectangular–triangular fins are analyzed. An optimization study has been performed to establish data for optimum heat transfer rate, cold fluid Biot number, fin efficiency, and fin effectiveness. If properly designed, a cascaded rectangular–triangular fin can be more effective than a rectangular or a triangular fin.

Establishment of Modified-One-Dimensional and Two-Dimensional Models for Two-Directional Heat Conduction in a Wet Fin Assembly

Abstract This paper deals with an analysis of two-dimensional temperature distribution within a rectangular fin assembly under wet conditions and subject to convective condition at the primary inner wall. An analytical method based upon the separation of variables was suggested to determine the two-dimensional temperature field. A modified one-dimensional model was used to more closely approximate the results of the two-dimensional model; a one-dimensional classical model was also elaborated to provide a basis for comparison, allowing the two-dimensional effect to be established in the case of wet fins. Next, wet fin efficiency was determined. To establish the merit of the present work in considering the two-dimensional effect in wet fins, the results of the two-dimensional model were compared with those obtained from the one-dimensional classical models, demonstrating a considerable difference in their results for various design and psychrometric conditions. The wet-fin analysis presented herein is equally suitable for dry-surface fins by accounting for the absence of latent heat transfer.

Smoke Control of a Car Park by Means of CFD Analyses Using Jet Fans

Analysis and interpretation of daily emission ventilation with fire ventilation systems in indoor parking lots coupling with jet fans have been done by a CFD program. The ventilation of an eight-story parking lot in Istanbul is carried out and the investigation for a simplified one-story of this system is also considered. The placement of jet fans has been identified on the basis of eliminating dead jones in the passage with the help of air flow analysis. Therefore, the present study may be of great importance as both the fire and smoke can be evacuated effectively by using the optimal position of jet fans in the parking lots to maintain a less polluted atmosphere inside.Copyright