The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
An exergy balance of a system helps to identify causes of losses. Establishing an exergy balance necessitates correction terms if environmental conditions change over the time period under consideration or the system is moving with respect to the environment. Applications show that these effects are considerable in some cases. On the other hand an exergy balance is also a means for checking a computational...
A very small oil-in-glass tube thermal energy storage (TES) system is designed to allow for rapid heat transfer experiments. An electrical hot plate in thermal contact with a steel spiral coil (SSC) is used to charge the TES system under different hot plate temperatures and under different average charging flow rates. Thermal performance during charging is presented in terms of the axial temperature...
Combined heat, cooling and power (CHCP) systems are interesting for the supply of different energy services in urban districts and in large buildings. CHCP systems utilize a fuel's energy to a greater extent, because the cogenerated heat can be used for heating in winter as well as for cooling in summer with an absorption refrigerator. The use of thermal energy storage (TES) provides the additional...
A small glass tube containing oil and glass pebbles is constructed to evaluate rapidly the volumetric heat transfer characteristics during charging. An electrical hot-plate in thermal contact with a steel spiral coil is used to charge the oil/pebble-bed storage under different average charging flow rates. The heat transfer characteristics are presented in terms of the average temperature of the oil,...
Stearic acid/expanded graphite composites with different mass ratios were prepared by absorbing liquid stearic acid into the expanded graphite. In the composite materials, the stearic acid was used as the phase change material for thermal energy storage, and the expanded graphite acted as the supporting material. Fourier transformation infrared spectroscopy, X-ray diffraction, scanning electron microscopy...
This paper describes the theoretical rationale for a new low temperature phase-change desalination process, and six examples of applications to illustrate how this process can be engineered for sustainable desalination. In this process, brackish water is evaporated at near-ambient temperatures under near-vacuum pressures created by the barometric head without any mechanical energy input. Thermodynamic...
In this study, energy and exergy analyses are carried out for the charging period of an ice-on-coil thermal energy storage system. The present model is developed using a thermal resistance network technique. First, the time-dependent variations of the predicted total stored energy, mass of ice, and outlet temperature of the heat transfer fluid from a storage tank are compared with the experimental...
A series of MicroPCMs with gelatin-gum arabic shell, polyurethane shell and styrene-based copolymer shell were fabricated via complex coacervation, interfacial polymerization and suspension polymerization, respectively. Furthermore, a novel MicroPCMs with styrene-divinylbenzene copolymer as inner shell and polyurethane as outer shell was investigated, where styrene and divinybenzene were employed...
Thermal energy storage is an expanding field within the subject of renewable energy technologies. After a listing of the different possibilities available for energy storage, this paper provides a comparison of various materials for High Temperature Thermal Energy Storage (HTTS). Several attributes and needs of each solution are listed. One in particular is using the latent heat as one of the most...
TES (Thermal energy storage) can enhance energy systems by reducing environmental impact and increasing efficiency. Thermochemical TES is a promising new type of TES, which permits more compactness storage through greater energy storage densities. In this article, closed and open thermochemical TES is investigated using energy and exergy methods. The latter method enhances assessments of made using...
The solidification process in encapsulated ice thermal energy storage (EITES) system is simulated for water-filled capsules while neglecting storage tank wall effects and heat penetration. Energy and exergy efficiencies were calculated while varying capsule shape, inlet Heat Transfer Fluid (HTF) temperature as well as HTF flow rate. 105 test cases are conducted including seven geometries, five inlet...
A novel type of bulk electricity storage – electrothermal energy storage (ETES) – is presented. The concept is based on heat pump and heat engine technologies utilizing transcritical CO2 cycles, storage of pumped heat in hot water, and ice generation and melting at the cold end of the cycles. The paper first describes the growing need for large scale electrical energy storage and the role of storage...
A novel technique for solving a dynamic optimal chiller loading problem is presented. This method reduces the complexity of the dynamic problem by considering all chillers to be a single, optimal chiller, which significantly reduces the number of decision variables. A static optimal chiller loading problem is solved as a sub-problem to give the optimal total power required at each time interval. The...
The aim of this work is to investigate design improvements of a shell-and-tube latent heat thermal energy storage unit using an approach based on the analysis of entropy generation. The study is conducted by means of a computational fluid-dynamic (CFD) model which takes into account phase change phenomenon by means of the enthalpy method. Thermal-fluid dynamic problem is solved both for the phase...
A latent heat storage nanocomposite made of stearic acid (SA) and multi-walled carbon nanotube (MWCNT) is prepared for thermal energy storage application. The thermal properties of the SA/MWCNT nanocomposite are characterized by SEM (scanning electron microscopy) and DSC (differential scanning calorimeter) analysis techniques, and the effects of different volume fractions of MWCNT on the heat transfer...
The discontinuous nature of the solar energy forces to study the dynamic behavior of solar plants to characterize their operations, to deepen their process understanding and to improve the performance and maintenance. The present paper focuses on the dynamic simulation and control of concentrating solar plants with the aim to define a reasonably simplified layout as well as to highlight the main issues...
Three kinds of macro-encapsulated phase change materials (MacroPCMs) were fabricated, i.e., MacroPCMs with a single core–shell structure, MacroPCMs containing microencapsulated phase change materials (MicroPCMs), and composite macrocapsules of MicroPCMs/expanded graphite prepared by suspension-like polymerization followed by a piercing–solidifying incuber process. The morphology, microstructure, phase...
PA/GO (palmitic acid/graphene oxide) as PCMs (phase change materials) prepared by vacuum impregnation method, have high thermal conductivity. The GO (graphene oxide) composite was used as supporting material to improve thermal conductivity and shape stabilization of composite PCM (phase change material). SEM (Scanning electronic microscope), FT-IR (Fourier transformation infrared spectroscope) and...
This paper presents an innovative finned-plate latent heat thermal energy storage system for its integration in cogeneration systems. For optimization purposes it is very important to maximize the efficiency of the computational calculations. Therefore, three approaches are presented for the simulation of the same storage system: a numerical model, a simplified analytical one and a simplified numerical...
The quest towards energy conservative building design is increasingly popular in recent years, which has triggered greater interests in developing energy efficient systems for space cooling in buildings. In this work, energy efficient silver–titania HiTES (hybrid nanocomposites-based cool thermal energy storage) system combined with building A/C (air conditioning) system was experimentally investigated...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.