Sorption thermal storage for solar energy Yu, N.; Wang, R.Z.; Wang, L.W.
Progress in energy and combustion science,
10/2013, Letnik:
39, Številka:
5
Journal Article
Recenzirano
Sorption technologies, which are considered mainly for solar cooling and heat pumping before, have gained a lot of interests for heat storage of solar energy in recent years, due to their high energy ...densities and long-term preservation ability for thermal energy. The aim of this review is to provide an insight into the basic knowledge and the current state of the art of research on sorption thermal storage technologies. The first section is concerned with the terminology and classification for sorption processes to give a clear scope of discussion in this paper. Sorption thermal storage is suggested to cover four technologies: liquid absorption, solid adsorption, chemical reaction and composite materials. Then the storage mechanisms and descriptions of basic closed and open cycles are given. The progress of sorption materials, cycles, and systems are also reviewed. Besides the well-known sorbents like silica gels and zeolites, some new materials, including aluminophosphates (AlPOs), silico-aluminophosphates (SAPOs) and metal-organic frameworks (MOFs), are proposed for heat storage. As energy density is a key criterion, emphais is given to the comparison of storage densities and charging tempertures for different materials. Ongoing research and development studies show that the challenges of the technology focus on the aspects of different types of sorption materials, the configurations of absorption cycles and advanced adsorption reactors. Booming progress illustrates that sorption thermal storage is a realistic and sustainable option for storing solar energy, especially for long-term applications. To bring the sorption storage solution into market, more intensive studies in fields of evaluation of advanced materials and development of efficient and compact prototypes are still required.
•Three available seasonal heat storage technologies are covered in this review.•Seasonal heat storage can largely increase the solar fraction for space heating.•Well-developed sensible heat storage ...is still dominant in large-scale applications.•Latent and chemical storage need further investigations prior to practical use.•Latest studies and related projects are included.
Solar energy storage has been an active research area among the various solar energy applications over the past few decades. As an important technology for solving the time-discrepancy problem of solar energy utilisation, seasonal/long-term storage is a challenging key technology for space heating and can significantly increase the solar fraction. It widens the use of solar collectors and results in better solar coverage of the space heating demand. This paper reviews all three available technologies for seasonal heat storage: sensible heat storage, latent heat storage and chemical storage. Sensible heat storage is a comparatively mature technology that has been implemented and evaluated in many large-scale demonstration plants. Water, rock-sort material and ground/soil are frequently used as storage materials. Latent heat and chemical storage have much higher energy storage densities than sensible storage, which means that they can remarkably reduce the storage volume, and they seldom suffer from heat loss problems. However, the latter two technologies are currently still in the stages of material investigations and lab-scale experiments. The characteristics of each concept have been presented in detail in this review. The latest studies and related projects are reviewed. The paper is structured as follows: fundamental investigation on storage materials, existing plants or projects and future outlook.
Superelastic conducting fibers with improved properties and functionalities are needed for diverse applications. Here we report the fabrication of highly stretchable (up to 1320%) sheath-core ...conducting fibers created by wrapping carbon nanotube sheets oriented in the fiber direction on stretched rubber fiber cores. The resulting structure exhibited distinct short- and long-period sheath buckling that occurred reversibly out of phase in the axial and belt directions, enabling a resistance change of less than 5% for a 1000% stretch. By including other rubber and carbon nanotube sheath layers, we demonstrated strain sensors generating an 860% capacitance change and electrically powered torsional muscles operating reversibly by a coupled tension-to-torsion actuation mechanism. Using theory, we quantitatively explain the complementary effects of an increase in muscle length and a large positive Poisson's ratio on torsional actuation and electronic properties.
Preoperative evaluation of the number of lymph node metastasis (LNM) is the basis of individual treatment of locally advanced gastric cancer (LAGC). However, the routinely used preoperative ...determination method is not accurate enough.
We enrolled 730 LAGC patients from five centers in China and one center in Italy, and divided them into one primary cohort, three external validation cohorts, and one international validation cohort. A deep learning radiomic nomogram (DLRN) was built based on the images from multiphase computed tomography (CT) for preoperatively determining the number of LNM in LAGC. We comprehensively tested the DLRN and compared it with three state-of-the-art methods. Moreover, we investigated the value of the DLRN in survival analysis.
The DLRN showed good discrimination of the number of LNM on all cohorts overall C-indexes (95% confidence interval): 0.821 (0.785–0.858) in the primary cohort, 0.797 (0.771–0.823) in the external validation cohorts, and 0.822 (0.756–0.887) in the international validation cohort. The nomogram performed significantly better than the routinely used clinical N stages, tumor size, and clinical model (P < 0.05). Besides, DLRN was significantly associated with the overall survival of LAGC patients (n = 271).
A deep learning-based radiomic nomogram had good predictive value for LNM in LAGC. In staging-oriented treatment of gastric cancer, this preoperative nomogram could provide baseline information for individual treatment of LAGC.
•Evaluation of the lymph node metastasis (LNM) is the basis of individual treatment of locally advanced gastric cancer (LAGC).•Deep leaning radiomic nomogram (DLRN) based on CT images can preoperatively determine the number of LNM in LAGC.•DLRN is significantly superior to the routinely used clinical N stages, tumor size, and clinical model.•DLRN is significantly associated with the overall survival of LAGC.
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We present sensitive 850 m imaging of the Cosmological Evolution Survey (COSMOS) field using 640 hr of new and archival observations taken with SCUBA-2 at the East Asian Observatory's James Clerk ...Maxwell Telescope. The SCUBA-2 COSMOS survey (S2COSMOS) achieves a median noise level of 850 m = 1.2 mJy beam−1 over an area of 1.6 sq. degree (main; Hubble Space Telescope/Advanced Camera for Surveys footprint), and 850 m = 1.7 mJy beam−1 over an additional 1 sq. degree of supplementary (supp) coverage. We present a catalog of 1020 and 127 sources detected at a significance level of >4 and >4.3 in the main and supp regions, respectively, corresponding to a uniform 2% false-detection rate. We construct the single-dish 850 m number counts at S850 > 2 mJy and show that these S2COSMOS counts are in agreement with previous single-dish surveys, demonstrating that degree-scale fields are sufficient to overcome the effects of cosmic variance in the S850 = 2-10 mJy population. To investigate the properties of the galaxies identified by S2COSMOS sources we measure the surface density of near-infrared-selected galaxies around their positions and identify an average excess of 2.0 0.2 galaxies within a 13″ radius (∼100 kpc at z ∼ 2). The bulk of these galaxies represent near-infrared-selected submillimeter galaxies and/or spatially correlated sources and lie at a median photometric redshift of z = 2.0 0.1. Finally, we perform a stacking analysis at submillimeter and far-infrared wavelengths of stellar-mass-selected galaxies (M = 1010-1012 M ) from z = 0-4, obtaining high-significance detections at 850 m in all subsets (signal-to-noise ratio, S/N = 4-30), and investigate the relation between far-infrared luminosity, stellar mass, and the peak wavelength of the dust spectral energy distribution. The publication of this survey adds a new deep, uniform submillimeter layer to the wavelength coverage of this well-studied COSMOS field.
A theory on skyrmion size Wang, X. S.; Yuan, H. Y.; Wang, X. R.
Communications physics,
07/2018, Letnik:
1, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Abstract
A magnetic skyrmion is a topological object consisting of a skyrmion core, an outer domain, and a wall that separates the skyrmion core from the outer domain. The skyrmion size and wall ...width are two fundamental quantities of a skyrmion that depend sensitively on material parameters such as exchange energy, magnetic anisotropy, Dzyaloshinskii–Moriya interaction, and magnetic field. However, quantitative understanding of the two quantities is still very poor. Here we present a general theory on skyrmion size and wall width. The two formulas we obtained agree almost perfectly with simulations and experiments for a wide range of parameters, including most of the existing materials that support skyrmions.
The fundamental features of one kind of rarely known stratocumulus, which was termed as “Millipede Cloud,” occurred over the Eastern Pacific Ocean in 2017 were first documented by using Moderate ...Resolution Imaging Spectroradiometer (MODIS) satellite imagery. These clouds had long and meandering “central axes” extending from several hundreds to thousands kilometers, and a number of “radical cloud arms” extending several tens of kilometers in its two sides. Total 59 “Millipede Clouds,” 4 and 55 of them, were formed over the Northern and the Southern Hemispheres, respectively. Their environmental backgrounds were analyzed by using ERA5 reanalysis data and MODIS sensor Level‐2 data. The cloud top pressures of these “Millipede Clouds” were between 850 and 800 hPa, and their top heights were about 1–2 km. There existed “inversion layer” of air temperature near the cloud tops at 800 hPa, which strongly suggested that these clouds were lower stratocumulus in essence.
Plain Language Summary
“Millipede Cloud,” one kind of rarely known stratocumulus which looks like “Millipede” shape, is termed for the first time in this paper. It has an obvious “central axis” and a number of well‐organized “radial cloud arms” in two sides of the “central axis” extending in several tens of kilometers length. This paper introduces the fundamental features of “Millipede Clouds” occurred over the Eastern Pacific Ocean in 2017 from the perspective of satellite image. Totally, 59 “Millipede Clouds” were found to occur over the Eastern Pacific Ocean. Their geographic distribution, cloud top features and vertical structure of one typical case on 16 July 2017 were documented.
Key Points
The fundamental features of “Millipede Clouds” over the Eastern Pacific Ocean in 2017 were documented by using Moderate Resolution Imaging Spectroradiometer (MODIS) satellite imagery
The environmental backgrounds of these “Millipede Clouds” were analyzed by using ERA5 reanalysis data and MODIS data
The cloud top pressures of these “Millipede Clouds” are between 850 and 800 hPa, and their top heights are about 1–2 km
Thermal energy storage is a necessary technology for the application of renewable energy and low-grade thermal energy. Chemical heat storage has been proved to be a feasible and promising method to ...store thermal energy. As compared to other thermal energy storage methods, chemical heat storage exhibits high energy storage density as well as feasibility for long-duration energy storage. In this paper, the basic principle of the chemical heat storage is firstly elaborated. Then the selection criteria of the chemical reaction are given. The aim of this review is to provide an insight into the promising candidate reactions for chemical heat storage application. The associated reversible chemical reactions available for thermal energy storage systems are summarized. Ongoing research and development studies illustrate that chemical heat storage is a very favorable option for the different application when diverse promising candidate reactions are selected. As working temperature is one of the key parameters for thermal energy storage systems, emphasis is given to the judgment of application temperature range for chemical heat storage. The determination of applicative temperature range of reversible chemical reactions is discussed. Besides, the challenge and prospect of the chemical heat storage technology are analyzed in the paper.
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