Investigation Of Heat Transfer Phenomena Research Articles

Investigation of heat transfer phenomenon in a complex wavy divergent channel under the effects of thermal radiation, joule heating and electroosmosis

The heat transfer analysis in electro osmotic flow of nanofluid is studied through the complex wavy channel under the consideration of joule heat and thermal radiation effects. The Ellis fluid is considered a base fluid and gold particles are suspended in them. The complex system of equations is converted to dimensionless form with the help of dimensionless transformation and parameters. The concepts of longer wavelength and lower Reynolds number are utilized to simplify the problem and obtain the exact solution of velocity and temperature distribution by using the built-in command DSolve in the mathematical software MATHEMATICA 13.3. The graphs are plotted with the same software to check the effects of various parameters on velocity, temperature, heat transfer rate, and streamlines with the following range of parameters − 5 ≤ U H S ≤ 5 , 0 ≤ β ≤ 5 , 0 ≤ α ≤ 3 , 0 < k ≤ 5 , 0 ≤ ϕ ≤ 0.04 , 20 ≤ P r ≤ 28 , 0 ≤ R n ≤ 5 . The computational results reported that the electroosmotic parameter, Helmholtz-Smoluchowski velocity, and material parameter reduce the velocity in the initial region and enhance the final region of the channel. It is also noted that the velocity profile exhibits increasing and decreasing behavior in the initial and final region respectively with upgrading the values of volumetric concentration of nanoparticles. The heat transfer rate is strongly affected by material parameters α and β , thermal radiation parameter, Prandtl number, and joule heating and these parameters promote the heat transfer rate of the system. The novel research of the current study shows the examination of the heat transfer analysis of blood-gold nanofluid in the presence of an electrical double layer and thermal radiation with the help of the Ellis nanofluid flow model through a complex symmetric wavy channel. The results of the present investigation are useful for the early detection of renal diseases and monitoring of disease progression because of the unique properties of gold nanoparticles. The role of gold nanoparticles as imaging agents, drug delivery antioxidant properties, biosensing, targeted therapy, and renal clearance makes them the perfect choice for renal diseases.

Non-intrusive investigation of flow and heat transfer characteristics of a channel with a built-in circular cylinder

Interferometry-based experimental investigation of heat transfer phenomena associated with a channel fitted with a circular cylinder has been reported. Experiments have been performed with water as the working fluid, and the range of Reynolds number considered is 75 ≤ Re ≤ 165. The circular cylinder, placed at the inlet section of the channel, provides a blockage ratio of 0.5. The experimental methodology has been benchmarked against the results of transient numerical simulations. In order to assess the performance of the channel fitted with a circular cylinder for possible heat transfer enhancement from the channel wall(s), experiments have also been performed on a plane channel (without a cylinder). The interferometry-based experiments clearly highlighted the influence of the built-in cylinder in generating the flow instabilities and alterations in the thermal boundary layer profile along the heated wall of the channel. The phenomenon of vortex shedding behind the cylinder was successfully captured. A gradual increase in the vortex shedding frequency was observed with increasing Reynolds number. Quantitative data in the form of two-dimensional temperature distributions revealed an increase in the strength of wall thermal gradients in the wake region of the cylinder due to the periodic shedding of the vortices. In turn, a clear enhancement in the wall heat transfer rates was observed for the case of the channel fitted with a cylinder vis-à-vis the plane channel. To the best of the knowledge of the authors, the work reported is one of the first attempts to provide the planar field experimental data for a channel configuration with a built-in circular cylinder using non-intrusive imaging techniques and has the potential to serve as one of the benchmark studies for validating the existing as well as future numerical studies in the related area.

Convective heat transfer characteristics of low Reynolds number nanofluid flow around a circular cylinder

Numerical investigation of heat transfer phenomena of low Reynolds number nano-fluid flow over an isothermal cylinder is presented in this paper. Steady state governing equations (continuity, N–S and energy equations) have been solved using finite volume method. Stationary heat transfer, and flow characteristics over the cylinder have been studied for water based copper nanofluid with different solid fraction values. The effect of volume fraction of nano- particles on the fluid flow and heat transfer were investigated numerically. It was found that at a given Nusselt number, drag coefficient, re-circulation length, and pressure coefficient increase by increasing the volume fraction of nano-particles.

Experimental investigation of a packed bed thermal energy storage system

In this work experimental investigations on a thermal energy storage system with a solid material as storage media and air as heat transfer fluid will be presented. The experimental test rig, installed at the DIMCM of the University of Cagliari, consists of a carbon steel tank filled with freely poured alumina beads that allows investigations of heat transfer phenomena in packed beds. The aim of this work is to show the influence of the operating conditions and physical parameters on thermocline formation and, in particular, the thermal behaviour of the thermal energy storage for repeated charging and discharging cycles. Better charging efficiency is obtained for lower values of mass flow rate and maximum air temperature and for increasing aspect ratio. A decreasing influence of the metal wall with continuous operation is also highlighted. In conclusion, the analysis focuses on the thermal hysteresis phenomenon, which causes degradation of the thermocline and the reduction of the energy that can be stored by the accumulator as the repeated number of cycles increases.

Heat Transfer Characteristics of Low Reynolds Number Flow of Nanofluid Around a Heated Circular Cylinder

Numerical investigation of heat transfer phenomena over an isothermal cylinder, for low Reynolds number flow of nanofluid is presented. Conservation equation of mass, momentum and energy under steady state have been solved using finite volume method. Heat transfer characteristic and flow over the stationary cylinder has been studied for water based copper nano fluid with different solid fraction values. Local Nusselt number over the cylinder surface has been found to increase with increase in nano particle fraction as well as increase in flow strength, though, the physics behind the rise in two cases is entirely different. Local heat flux drops along the cylinder wall and increases with increase in nano particle fraction as well as Reynolds number. Neglecting buoyancy effect, flow separation angle is not affected by presence of nano particles in the base fluid.

In vitro investigation of heat transfer phenomenon in human immature teeth.

Background and aims. Heat generated within tooth during clinical dentistry can cause thermally induced damage to hard and soft components of the tooth (enamel, dentin and pulp). Geometrical characteristics of immature teeth are different from those of mature teeth. The purpose of this experimental and theoretical study was to investigate thermal changes in immature permanent teeth during the use of LED light-curing units (LCU).Materials and methods. This study was performed on the second mandibular premolars. This experimental investiga-tion was carried out for recording temperature variations of different sites of tooth and two dimensional finite element models were used for heat transfer phenomenon in immature teeth. Sensitivity analysis and local tests were included in the model validation phase. Results. Overall, thermal stimulation for 30 seconds with a low-intensity LED LCU increased the temperature from 28°C to 38°C in IIT (intact immature tooth) and PIT (cavity-prepared immature tooth). When a high-intensity LED LCU was used, tooth temperature increased from 28°C to 48°C. The results of the experimental tests and mathematical modeling illustrated that using LED LCU on immature teeth did not have any detrimental effect on the pulp temperature. Conclusion. Using LED LCU in immature teeth had no effect on pulp temperature in this study. Sensitivity analysis showed that variations of heat conductivity might affect heat transfer in immature teeth; therefore, further studies are required to determine thermal conductivity of immature teeth.

Investigation of Heat Transfer Phenomena in a Ventilated Disk Brake Rotor with Straight Radial Rounded Vanes

Investigation of Heat Transfer Phenomena in a Ventilated Disk Brake Rotor with Straight Radial Rounded Vanes