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Thermal Energy Storage Technologies
Published in Viorel Badescu, George Cristian Lazaroiu, Linda Barelli, POWER ENGINEERING Advances and Challenges, 2018
Kostantin G. Aravossis, Vasilis C. Kapsalis
Solar ponds are shallow bodies of water in which an artificially maintained salt concentration gradient prevents convention. The combination of heat collection, through the radiation adsorption passing the water layers, with long term storage can provide sufficient heat for the entire year (Rabl and Nielsen 1975). The absorbed radiation may be further increased with the dark colored bottom while the cover with an impermeable light transmitting heat insulating layer like the similar technique in swimming pools to avoid evaporation of water. Typically, there are three distinct convection layers, namely the lower zone (LCZ), the non-convective zone (NCZ) and the upper zone (UCZ), Fig. 4.
High resolution STEM/EDX spectral imaging to resolve metal distributions within ∼100 nm combustion generated ash particles
Published in Aerosol Science and Technology, 2019
Yueming Wang, Brian Van Devener, Xiaolong Li, Jost O. L. Wendt
All the ultrafine fly ash particles investigated in this work were generated in a 100 kW (rated) down-fired oxy-fuel combustor (OFC) at University of Utah’s industrial combustion and gasification research facility (ICGRF). OFC is a self-sustained pilot-scale reactor and it mainly consists of an ignition zone, a radiation zone, and a convection zone. OFC can be systematically controlled, and it operates at realistic stoichiometric ratios, with turbulent diffusion flames in ignition zone causing realistic temperature/time profiles, which are comparable to practical units. The ash aerosols are sampled downstream where the exhaust gases become laminar. The OFC has been extensively used in previous studies for various pulverized solid fuels including coal and biomass, and details regarding its configuration can be found elsewhere (Wang, Li, and Wendt 2018; Zhan et al. 2016; Zhang et al. 2011; Zhou et al. 2019).
Bridge durability design after EN standards: present and future
Published in Structure and Infrastructure Engineering, 2019
The right-hand side of Figure 6 sketches a typical chloride profile (black dots and dotted line). Fitting the solution of Fick’s second Law (Equations (3)–(5)), discussed later, requires disregarding some point(s) close to the surface, leading to the full black line, characterised by the surface concentration Cs (intercept with x = 0) and the apparent Coefficient of Diffusion D (which is lower the steeper the ‘slope’ of the curve). An alternative approach, followed by (fib, 2006), is to displace the origin of the chart a distance Δx to the right (see red lines in Figure 6), to where it is considered that the process is purely diffusive. This Δx portion is defined as ‘convection zone’. In any case, what is demonstrated is that assuming a purely diffusive process of chloride ingress is incompatible with experimental evidence and needs some accommodation.
Effects of a subadiabatic layer on convection and dynamos in spherical wedge simulations
Published in Geophysical & Astrophysical Fluid Dynamics, 2019
P. J. Käpylä, M. Viviani, M. J. Käpylä, A. Brandenburg, F. Spada
We perform three sets of simulations denoted as HD, RHD and MHD. In Set HD, we model non-rotating convection, where is varied to control the depth of the convection zone. The effect of increasing is to make radiative diffusion more efficient. This is particularly important in the deep parts of the domain where the temperature is high due to the strong temperature dependency of the heat conduction (, see (9)). Thus the expectation is that with higher values of , a radiative layer develops at the bottom of the domain. In the RHD runs, we take the HD runs and add rotation with , where s−1 is the mean solar rotation rate. In the MHD set, magnetic fields are added to the RHD setup to study the effects of stably stratified layers on the dynamo. Each set consists of four runs, denoted by a suffix running from 1 to 4, where the value of is systematically increased. A run with a fixed profile of K, denoted by a suffix “p”, is used as a reference in each set with the same variation of physical ingredients. The runs are listed in table 1.