Abstract
This study seeks to investigate the concept of using large waste rocks from mining operations as waste-heat thermal energy storage for remote arctic communities, both commercial and residential. It holds its novelty in analyzing such systems with an experimentally validated transient three-dimensional computational fluid dynamics and heat transfer model that accounts for interphase energy balance using a local thermal non-equilibrium approach. The system performance is evaluated for a wide range of distinct parameters, such as porosity between 0.2 and 0.5, fluid velocity from 0.01 to 0.07 m/s, and the aspect ratio of the bed between 1 and 1.35. It is demonstrated that the mass flow rate of the heat transfer fluid does not expressively impact the total energy storage capacity of the rock mass, but it does significantly affect the charge/discharge times. Finally, it is shown that porosity has the greatest impact on both fluid flow and heat transfer. The evaluations show that about 540 GJ can be stored on the bed with a porosity of 0.2, and about 350 GJ on the one with 0.35, while the intermediate porosity leads to a total of 450 GJ. Additionally, thermal capacity is deemed to be the most important thermophysical factor in thermal energy storage performance.
Highlights
Increasing population and economic growth in the past years has significantly amplified fossil fuel dependency and its impact on the environment [1]
Such technologies aid in the reduction of both carbon footprints and energy costs from small to big scales, being even deemed vital in some applications [4,5]. Such technologies are mostly used in solar energy applications, mainly concentrated solar power plants (CSP) [3,6,7,8] and solar district heating [9,10,11,12,13], but waste-heat storage systems can take great advantage of their use [14,15,16,17]
This study focuses on a Thermal energy storage (TES) system being charged by a stream of hot air, the product of the exhaust from a local power plant
Summary
Increasing population and economic growth in the past years has significantly amplified fossil fuel dependency and its impact on the environment [1]. Cascetta et al worked on experimental and numerical tests, focusing on their comparison, and achieved satisfactory results on simulations that had input temperatures from experiments [31] When it comes to design and operation of porous media storage systems, two important parameters ought to be highlighted: the rate of heat transfer between fluid and solid domains, and the power necessary to run the heat transfer fluid through the system. This research holds its novelty on the investigation of the effects of several physical characteristics of a rock-bed TES charged through waste heat for space heating applications Such a task is achieved employing a three-dimensional, transient model, based on the LTNE approach, by which heat transfer and fluid flow within the packed bed thermal storage system are studied through the use of computational fluid dynamics (CFD) models. The impact of several parameters on the performance of the large-sized, rock-bed waste-heat storage for remote communities is evaluated for several distinct scenarios, while focusing on the simultaneous impact of these with changes in system dimensions, i.e., aspect ratios (AR), which to the best knowledge of the authors, has not been performed before
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