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Generation
Published in Joel L. Plawsky, Transport Phenomena Fundamentals, 2020
Constant sources of heat generation are very common occurrences. They may result from radioactive decay or more commonly from Joule heating. Joule heating occurs when we pass a current through a material having a measurable electrical resistance. The nature of the problem illustrating this form of generation is shown in Figure 5.9. Here we have a wire of resistivity, ρr = 1.0 × 10−7 Ω · m, and diameter, d = 0.0033 m, carrying a current I. The metal wire has a thermal conductivity of 20 W/mK. The wire is covered with a layer of electrical insulation that has an extremely low electrical conductivity, but whose thermal conductivity, k, is on the order of 0.05 W/mK. We would like to calculate the critical insulation thickness to insure the maximum heat transfer rate from the wire. We must assume that the wire will be carrying the maximum current allowed by the National Electric Code, I = 35 amps. The wire is also exposed to an environment where the average heat transfer coefficient to the atmosphere is on the order of 10 W/m2K.
Improving the Performance of Shape Memory Polymers
Published in Witold M. Sokolowski, Cold Hibernated Elastic Memory Structure, 2018
When a material becomes electrically conductive, the possibility arises to heat the material through resistive or Joule heating. An electric current is passed through a conductor and releases heat. According to the most general and fundamental formula for Joule heating, P=VI=V2/R with P the power, or energy per unit time, converted from electrical energy to thermal energy, V the voltage drop over the sample, I the electrical current through the sample, and R the electrical resistance of the sample. So, when attached to a power source, the lower the resistivity or better conducting the material, the higher the energy converted. As with microwave heating, the bulk of the material is heated, which is lot faster than conventional surface heating. Figure 6.8 shows the temperature-time graph for a sample of CNT-filled SMP undergoing four cycles of applying voltage and cooling. The increase of heating rate after the first cycle is probably due to aligning of the CNTs into a more conductive network (Figure 6.9).
Ablation
Published in John G Webster, Minimally Invasive Medical Technology, 2016
The bio-heat equation (15.1) governs the temperature and potential distributions in the tissue during RF ablation. Joule heating arises when energy dissipated by an electric current flowing through a conductor is converted into thermal energy() ρc∂T∂t=∇.k∇T+J⋅E−Qh.
Boundary layer formations over a stretchable heated cylinder in a viscoelastic fluid with partial slip and viscous dissipation effects
Published in Numerical Heat Transfer, Part A: Applications, 2023
To investigate the consequences of varying magnetic field strength on the flow and resulting heat transfer, Figures 4a, b are included. Joule heating is the process by which the flow of an electric current through a conductor generates heat. It is a significant phenomenon because it can be used to generate heat for a variety of applications. It is obvious that vertical magnetic field sets up a drag that opposes momentum transport due to which velocity boundary layer declines, as demonstrated from the results of Figure 4a. Moreover, the contribution of Joule heating toward heat generation grows upon increasing the magnetic interaction parameter as can be noticed from last term of the energy equation Eq. (4). Eventually, thermal boundary layer becomes substantially broader whenever higher value of is invoked. Such observation is in compliance with the findings of other authors (see [39, 40] etc.).
Analysis of nanofluid flow subject to velocity slip and Joule heating over a nonlinear stretching Riga plate with varying thickness
Published in Waves in Random and Complex Media, 2022
Zakir Hussain, Zeenat Bashir, M. S. Anwar
Joule heating occurs when an electric current passes through any conducting material while the moving particles collide with each other. The investigators are concerned to enhance the coherence of sundry mechanical and industrial machinery structures. These complications can be restrained to decline the temperature produced by Joule heating. Babazadeh et al. [50] addressed the magnetic force effect on nanomaterial flow between two sheets. Thermal investigation of nano-materials in a curved channel for peristaltic flow has been documented by Riaz et al. [51]. Ellahi et al. [52] discussed cavitation of spherical type bubbles in tube nozzle. The influence of varying characteristics on non-Newtonian liquid flow with double diffusion is analyzed by Waqas et al. [53].
Numerical study on the effect of fin length variation on the thermal performance of a bus duct conductor
Published in Numerical Heat Transfer, Part A: Applications, 2023
Mark Selvan, Mohd Sharizal Abdul Aziz, M. S. Nurulakmal, H. P. Ong, C. Y. Khor
The heat source was a crucial piece of the puzzle in the simulation setup. The heat source in this study was mainly from the Joule losses of the copper conductor. Joule heating, also known as resistive heating, is the process of generating heat when a current is passed through a conductor. The heat loss in the form of Joule losses for one volumetric heat source was considered. As both heat and electricity were involved, the thermal-electric analysis system was employed to study the magnitude of the heat source. Eqs. (11) and (12) were used to calculate Joule losses from the bus bar using the analytical method. where