Magnetohydrodynamic Effect on Thermal Transport by Silver Nanofluid Flow in Enclosure with Central and Lower Heat Sources

2021 ◽  
pp. 1-14
Author(s):  
Mahalakshmi Thangavelu ◽  
Nithyadevi Nagarajan ◽  
Ruey-Jen Yang
Keyword(s):  
Thermal Transport ◽  
Heat Sources ◽  
Nanofluid Flow ◽  
Magnetohydrodynamic Effect ◽  
Lower Heat

scholarly journals A new regime of nanoscale thermal transport: Collective diffusion increases dissipation efficiency

2015 ◽  
Vol 112 (16) ◽  
pp. 4846-4851 ◽  
Author(s):  
Kathleen M. Hoogeboom-Pot ◽  
Jorge N. Hernandez-Charpak ◽  
Xiaokun Gu ◽  
Travis D. Frazer ◽  
Erik H. Anderson ◽  
...  
Keyword(s):  
Integrated Circuits ◽  
Free Path ◽  
Thermal Management ◽  
Thermal Transport ◽  
Heat Dissipation ◽  
Mean Free Path ◽  
Heat Sources ◽  
Nanoscale Systems ◽  
Nanoscale Thermal Transport ◽  
Thermal Therapies

Understanding thermal transport from nanoscale heat sources is important for a fundamental description of energy flow in materials, as well as for many technological applications including thermal management in nanoelectronics and optoelectronics, thermoelectric devices, nanoenhanced photovoltaics, and nanoparticle-mediated thermal therapies. Thermal transport at the nanoscale is fundamentally different from that at the macroscale and is determined by the distribution of carrier mean free paths and energy dispersion in a material, the length scales of the heat sources, and the distance over which heat is transported. Past work has shown that Fourier’s law for heat conduction dramatically overpredicts the rate of heat dissipation from heat sources with dimensions smaller than the mean free path of the dominant heat-carrying phonons. In this work, we uncover a new regime of nanoscale thermal transport that dominates when the separation between nanoscale heat sources is small compared with the dominant phonon mean free paths. Surprisingly, the interaction of phonons originating from neighboring heat sources enables more efficient diffusive-like heat dissipation, even from nanoscale heat sources much smaller than the dominant phonon mean free paths. This finding suggests that thermal management in nanoscale systems including integrated circuits might not be as challenging as previously projected. Finally, we demonstrate a unique capability to extract differential conductivity as a function of phonon mean free path in materials, allowing the first (to our knowledge) experimental validation of predictions from the recently developed first-principles calculations.

scholarly journals Combined heat pump-district heating network energy source

2018 ◽  
Vol 49 ◽  
pp. 00063
Author(s):  
Karolina Kurtz-Orecka ◽  
Wojciech Tuchowski
Keyword(s):  
Energy Efficiency ◽  
Heat Source ◽  
Heat Pump ◽  
District Heating ◽  
Heat Sources ◽  
Medium Temperature ◽  
Efficient Operation ◽  
Energy Needs ◽  
Working Medium ◽  
Lower Heat

The article describes the innovative combination of the heat pump's operation with the heating network called as cHPNes. The heat pump's lower heat sources used so far are air, water or ground. Their efficiency is usually incoherent with the energy needs of recipients. In the period of the lowest temperatures of the source, we have the highest demand for heat in the supplied facility. A combination of the water heat pump and the heating network is aimed at increasing the energy efficiency (COP) of the heat source and indirectly increasing the participation of renewable energy in the energy balance of buildings. The essence of the new solution is the use of returning water in the heating network to supply the heat pump evaporator. The working medium temperature of the heating network on the return in the all-year cycle is stable and high, which allows further use of energy of the heating water on the return. These are the two main advantages of network water used as the lower heat source, allowing for stable and efficient operation of the heat pump with COP above 13. This solution is a response to the need to improve the energy efficiency of highly urbanized spaces.

scholarly journals Analysis of Peristaltic Motion of a Nanofluid with Wall Shear Stress, Microrotation, and Thermal Radiation Effects

2016 ◽  
Vol 2016 ◽  
pp. 1-15 ◽  
Author(s):  
C. Dhanapal ◽  
J. Kamalakkannan ◽  
J. Prakash ◽  
M. Kothandapani
Keyword(s):  
Shear Stress ◽  
Thermal Radiation ◽  
Radiation Effects ◽  
Heat Sources ◽  
Nanofluid Flow ◽  
Long Wavelength ◽  
Flow Reynolds Number ◽  
Micropolar Nanofluid ◽  
Flow Variables ◽  
Coupling Number

This paper analyzes the peristaltic flow of an incompressible micropolar nanofluid in a tapered asymmetric channel in the presence of thermal radiation and heat sources parameters. The rotation of the nanoparticles is incorporated in the flow model. The equations governing the nanofluid flow are modeled and exact solutions are managed under long wavelength and flow Reynolds number and long wavelength approximations. Explicit expressions of axial velocity, stream function, microrotation, nanoparticle temperature, and concentration have been derived. The phenomena of shear stress and trapping have also been discussed. Finally, the influences of various parameters of interest on flow variables have been discussed numerically and explained graphically. Besides, the results obtained in this paper will be helpful to those who are working on the development of various realms like fluid mechanics, the rotation, Brownian motion, thermophoresis, coupling number, micropolar parameter, and the nondimensional geometry parameters.

Natural Convection Cooling of Multiple Heat Sources in Parallel Open-Top Cavities Filled With a Fluorinert Liquid

1998 ◽  
Vol 120 (1) ◽  
pp. 73-81 ◽  
Author(s):  
M. Behnia ◽  
A. A. Dehghan ◽  
H. Mishima ◽  
W. Nakayama
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Heat Source ◽  
Alumina Ceramic ◽  
Heat Sources ◽  
Flow And Heat Transfer ◽  
Discrete Heat Sources ◽  
Vertical Walls ◽  
Convection Cooling ◽  
Lower Heat

Natural convection immersion cooling of discrete heat sources in a series of parallel interacting open-top cavities filled with a fluorinert liquid (FC–72) has been numerically studied. A series of open-top slots which are confined by conductive vertical walls with two heat sources on one side are considered. One of the slots is modeled and simulated. The effect of the separation between the heat sources on the flow and heat transfer characteristics of the wall and the effect of strength of the lower heat source (which location is upstream of the other one) on the flow and heat transfer of the upper heat source are considered. The wall thermal conductivity considered ranges from adiabatic to alumina-ceramic. The results of bakelite and alumina-ceramic are shown, which are commonly used as wiring boards in electronic equipment. It is found that conduction in the wall is very important and enhances the heat transfer performance.

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