Controlling and maximizing effective thermal properties by manipulating transient behaviors during energy-system cycles. (July 2016)

• Record Type: Journal Article
• Authors: Gao, Zhaojing; Shih, Tien-Mo; Merlitz, Holger; Chen, Zhong
• Is Part Of: International communications in heat and mass transfer. Volume 75(2016:Jul.)
• Page Start: 137
• Page End: 146
• Publication Date: 2016-07
• Subjects: Conductivity -- Capacity -- Nonlinear thermal bias -- Transient states -- Ocean energy; Heat -- Transmission -- Periodicals; Mass transfer -- Periodicals; Chaleur -- Transmission -- Périodiques; Transfert de masse -- Périodiques; Heat -- Transmission; Mass transfer; Periodicals; 621.4022
• DOI: 10.1016/j.icheatmasstransfer.2016.04.015
• Languages: English
• ISSNs: 0735-1933

Abstract

Abstract: Transient processes generally constitute part of energy-system cycles. If skillfully manipulated, they actually are capable of assisting systems to behave beneficially to suit designers' needs. In the present study, behaviors related to both thermal conductivities ( κ ) and heat capacities ( c v ) are investigated. Three major findings validated by COMSOL simulations and micro-Hamiltonian-Oscillator analyses are reported: (1) effective κ and effective c v can be controlled to vary from their intrinsic material-property values to a few orders of magnitude larger; (2) a parameter, tentatively named as "nonlinear thermal bias", is identified and can be used as a criterion in estimating energies transferred into the system during heating processes; (3) For bodies of fluids confined by a cold bottom and a hot top, it may be feasible to install a propeller that can be turned by a weak buoyancy force induced by the top-to-bottom heat conduction via the propeller, provided that densities of the propeller and the fluid are similar. Such a turning motion serves double purposes of performing the hydraulic work and increasing the effective κ of the propeller. Hence, hot-top-and-cold-bottom fluid-filled enclosures (e.g., oceans) that induce nearly no buoyancy flows may now, in principle, become energy-harnessing sources.