Heat Transfer最新文献

The key attention of this work is on the impact of suction/injection on the free convective flow of a viscous fluid passing between two infinite, parallel, vertical and porous plates with non-Fourier effects. The analysis focuses on a porous channel with boundaries featuring a steady–periodic temperature regime. The governing equations, representing velocity(momentum) and temperature(energy) fields, are well-stated in dimensional form. Employing a separation technique, the momentum and energy equations are separated into steady and periodic components. On solving, the resulting second-order ordinary differential equations derived, revealed the expressions for velocity and temperature in dimensionless form. However, the study investigates the influence of various flow parameters used in this work, including suction/injection $��\; ���\left(�\; �s�\; �\right)���$, heat source/sink $��\; ���\left(�\; �H�\; �\right)���$, Strouhal number $��\; ��\left(�\; �\mathrm{St}�\; �\right)��$, Prandtl number $��\; ��\left(�\; �P�\; �r�\; �\right)��$, and dimensionless relaxation time $��\; ���\left(�\; �\gamma �\; �\right)���$

In this study, experimental and computational studies of the impact of forced convective flow on the heat transfer characteristics of staggered pin fins with perforations are investigated in a rectangular channel at constant heat flux with Reynolds numbers (Re) of 2 × 10³–12 × 10³. In particular, cylindrical pin fins with circular longitudinal (L) perforation, longitudinal/transverse (LT) perforation, and longitudinal/transverse/vertical (LTV) perforation perforations are compared to solid pin fins to find out how adding different perforation arrays affects overall heat transfer performance and also to find the best perforation configuration for maximum performance. ANSYS-FLUENT is employed for numerical simulation, validated by experimental data. Experimental validation is conducted by attaching the heat sink to a Peltier module, inducing heat generation through current on one face in the Armfield Free and Forced Convection Heat Transfer Service Units HT 19 and HT10XC. Results highlight significant increases in Nusselt number (Nu) for perforated pins compared to solid pins, with L perforations at 8%, LT perforations at 33%, and 67% for LTV perforated pins due to transverse perforations that act as slots, which stir up the primary flow and induce secondary flow generated by vertical perforations. Regarding pressure drops, L perforations reduce by 9%, LT by 19%, and LTV by 27% compared to solid pins. The overall enhancement ratio peaks at the minimum Reynold number, notably achieving a 38% increase in the LTV perforation pin fin array. This innovative study holds promise for diverse electronic applications, offering enhanced heat transfer performance in electronic cooling systems.

In cold climates or winter countries, maintaining optimal room temperatures is essential for comfort and energy efficiency. Conventional square or rectangle-shaped rooms often face challenges in achieving efficient heat transfer (HT) and uniform temperature distribution. To address these limitations, this study has been explored using curved corner cavities, varying their aspect ratio (AR = 1.0 and 0.5), and incorporating a circular shape cooler to enhance HT within the room. The curved corners promote better airflow circulation, creating a more efficient HT environment. The dimensionless governing equations and corresponding boundary conditions are solved numerically using the finite element method. This research aims to assess the optimized HT and entropy production within a curved corner cavity, varying their AR and enclosing a circular shape cooler to determine the most effective configuration for maximizing HT and energy efficiency in winter conditions. This study reveals that in the case without a cooler (WOC), the average Nusselt number ($��\; ��N�\; �u_{��\; �a�\; �v�\; �g��}��$) is higher in the curved rectangle cavity compared with the curved square cavity for all $��\; ��R�\; �a��$ values. Using the curved square (AR = 1.0), $��\; ��N�\; �u_{�a�\; �v�\; �g�}��$

A novel approach to assess the thermal conformance between two metallic materials under transient conditions was proposed in the present investigation. Thermal conformance parameters (ƞ, ϴ, t_g) were defined to quantify the contact condition between a metal–metal interface. To assess the effect of load and thermophysical properties of the sink and source materials on the degree of thermal conformance, a thermal conformance assessment parameter (TCAP) was proposed. Heat flux transients at the thermal interface was estimated by using an inverse heat conduction approach for various similar and dissimilar metallic surfaces in contact such as Cu─Cu, Al─Al, Al─Cu, and Cu─Al under both load and no load conditions. Commercially available silicone grease (SG) and thermal grease (CTG) were used as thermal interface materials (TIMs). The thermal conformance parameters increased with the increase in load for all the combinations of interfaces with and without TIMs. It was observed that, except for the copper–copper combination, thermal conformance parameters showed a linear relation with the TCAP. The enhancement in the heat transfer due to the application of load and TIM was validated by determining the maximum temperature difference (∆T_max) across the interface. The experimental study revealed that the ∆T_max decreases with the application of load and application of TIM leading to enhanced heat transfer. For the copper–copper combination, the thermal conformance depended solely on the load applied. Due to the lower thermal resistance offered by copper source/sink materials, the interfacial resistance between them becomes a dominant factor. The effect of TIM on heat absorbed by the sink was significant for the Cu/Cu interface.

This research paper focused on investigating the influence of various factors on steady Couette flow beneath a permeable bed. Factors studied included aligned magnetic field, thermal radiation, temperature gradient heat source, viscous dissipation, and Joules dissipation. The momentum and energy equations governing flow and heat transmission were analytically solved to predict the generation of entropy. The findings were visually presented through graphical representations, which effectively demonstrated the effect of these factors on the fluid's velocity, temperature, entropy production, and Bejan number. In addition, the shear stress and rate of heat transfer coefficient at the channel walls were computed and their behavior was documented in tables to provide further insights.

The microchannel heat sink with periodically arranged triangular cavities and arc-shaped ribs (MC-ARTC) is investigated numerically under the conditions of Reynolds number 147–736. The effects of triangular cavities and arc-shaped ribs on velocity, pressure, and temperature distribution in the channel are analyzed in comparison with a rectangular microchannel heat sink, microchannel heat sink with arc-shaped ribs, and microchannel heat sink with triangular cavities. The results show that the triangular cavity and the arc-shaped rib have important effects on the flow and heat transfer characteristics in the microchannel heat sink. Both rib and cavity can cause a change in fluid flow direction and disturb the development of the flow boundary layer. The fluid flow and heat transfer characteristics of microchannels are improved. Among the four microchannels, the MC-ARTC has the optimum comprehensive performance for the combined effect of the rib and cavity. Relative cavity width ($��\; ��\beta ��$) and relative rib height ($��\; ��\theta ��$) are also defined to study the effects of cavity width ($��\; ��W_t��$ = 89–200 μm) and rib height ($��\; ��H_a��$ = 8.9–28.9 μm) on the flow and heat transfer characteristics. It is found that the heat transfer of MC-ARTC is enhanced with increasing $��\; ��W_t��$ and