•Thermal energy storage heat exchanger utilizing PCMs is designed and built.•Optimal plate-plate spacing is found to achieve maximum system performance.•Effectiveness greater than 80% at 4795 W power ...output was achieved.•The number of modular units is found for a targeted heat storage capacity.
The study presents an experimental investigation of a thermal energy storage vessel for load-shifting purposes. The new heat storage vessel is a plate-type heat exchanger unit with water as the working fluid and a phase change material (PCM) as the energy storage medium. The thermal characteristics of the heat exchanger such as heat transfer coefficient, effectiveness, efficiency, water exit temperature, heat storage rate, total energy storage capacity and storage time were experimentally evaluated as a function of various inlet conditions. The compact parallel plate design showed an enhanced the performance compared to conventional storage systems with an effectiveness up to 83.1% even when a PCM of low thermal conductivity is used. The proposed phase change energy storage system not only can deliver substantial benefits as a thermal energy storage medium, but also provides cost savings in infrastructure, equipment, and maintenance/operations compared to conventional systems.
Suitable high temperature PCMs for thermal energy storage are characterized and proposed as a promising candidate for nuclear reactor safety applications in the containment structure in the event of ...LOCA accidents. PCM with phase transition temperature in the range 70 °C to 90 °C and latent heat of around 200 kJ/kg or higher can be utilized to reduce temperature and pressure in the reactor containment during accidents. Reviewing the available data for high-temperature PCMs indicated significant deficiencies in published data and further investigations revealed that a material misrepresentation has occurred in some cases. Octadecanoic acid was identified as the most promising PCM for this application and the temperature-dependent thermo-physical properties and phase change behavior of octadecanoic acid were studied in detail. The results closed the gaps in the existing experimental database, studied the feasibility of utilizing several PCM candidates, measured the currently unknown temperature-dependent properties for optimum PCM, measured the specific heat capacity in the overlap and phase transition regions, and provided a valuable database for future design concepts, experiments and predictive simulation and modelling models.
•Phase change materials has potential uses for passive safety in nuclear reactor systems.•Comprehensive thermophysical properties of octadecanoic acid are measured and published for the first time.•Modulated DSC measurements were used to obtain previously-impossible measurements.
Sigma-nucleus potential in A=28 Noumi, H; Saha, P K; Abe, D ...
Physical review letters,
08/2002, Letnik:
89, Številka:
7
Journal Article
Recenzirano
We have studied the (pi(-),K+) reaction on a silicon target to investigate the sigma-nucleus potential. The inclusive spectrum was measured at a beam momentum of 1.2 GeV/c with an energy resolution ...of 3.3 MeV (FWHM) by employing the superconducting kaon spectrometer system. The spectrum was compared with theoretical calculations within the framework of the distorted-wave impulse approximation, which demonstrates that a strongly repulsive sigma-nucleus potential with a nonzero size of the imaginary part reproduces the observed spectrum.
The spin-orbit splitting of Lambda single-particle states in (13)(Lambda)C was measured. The 13C(K-,pi(-))(13)(Lambda)C reaction was used to excite both the 1/2(-) and 3/2(-) states simultaneously, ...which have predominantly 12C(0(+)) x p(Lambda) configuration. gamma rays from the states to the ground state were measured in coincidence with the pi(-)'s, by which ls splitting was found to be 152+/-54(stat)+/-36(syst) keV. The value is 20-30 times smaller than exhibited by the ls splitting in the nuclear shell model. This value gives us new insight into the YN interaction.
•Thermal enhanced form-stable binary eutectic PCM of a methyl ester and fatty acid, is studied for thermal energy storage.•Hydroxypropyl ether cellulose was introduced so that PCMs become ...shape-stable, and overcome liquid leakage problem.•Nano-graphene platelets (NGPs) were added in order to enhance the heat transfer.•Experimentally studied all the important thermo-physical properties of the enhanced form-stable PCM.•The phase transition temperatures, and enthalpy of fusion were thermally stable over a postulated lifetime of 80 years.
This study presents the development of form-stable eutectic mixtures, modified with nanoscale structures for enhanced thermal performance. These additives may result in the next generation of phase change materials (PCMs) for thermal energy storage systems. An appropriate gelling or thickening agent (2-hydroxypropyl ether cellulose) is introduced so that the PCM will lose its fluidity, become form-stable, and the liquid leakage problem will be overcome. Nano-graphene platelets (NGPs) are added in order to enhance the thermal properties and overall heat transfer. Differential scanning calorimetry (DSC) was carried out for the thermal analysis of the PCMs. The paper experimentally studied in detail the enhanced thermo-physical properties required for stimulating and modelling the PCM in energy storage applications such as specific heat, thermal diffusivity, thermal conductivity, enthalpy, and density. The principle of the T-history method was applied using a parallel plate heating/cooling guarded plate apparatus to determine the true phase transition temperatures of bulk PCM. The supercooling of the enhanced shape stable mixture was found to be less than 0.1°C. The thermal reliability test indicated that the enhanced form-stable eutectic mixture had reliable thermal performance over a postulated lifetime of 80 years. As a result, the developed form stable PCM eutectic mixture is a promising material for thermal energy storage.
•A binary system of methyl palmitate and lauric acid with ratio of 60/40 was found to be an optimum PCM eutectic mixture.•The eutectic PCM has a suitable phase transition temperature (Tm=25.6°C, ...Tf=20.2°C) within the comfort temperature range and high latent heat capacity (ΔHm=205.4J/g, ΔHf=205.8J/g).•Minimal volume change of less than 5.3% during phase transition; suitable for encapsulation in panels or capsules for any application.•Negligible change in thermal performance after 350 thermal cycles.
A series of binary mixtures of Methyl Palmitate (MP) and Lauric Acid (LA) were prepared and investigated, aiming for potential phase change material (PCM) for thermal energy storage systems. The thermal analysis of the PCM binary mixtures was investigated by means of Differential Scanning Calorimetry (DSC). A theoretical and experimental determination of the eutectic mixture was established. The results indicated that the eutectic binary mixture of 60%MP and 40%LA has desirable properties of phase transition temperatures within the comfort temperature range (Tm=25.6°C, Tf=20.2°C) and high latent heat capacity (ΔHm=205.4J/g, ΔHf=205.8J/g). The paper experimentally studied the other important thermo-physical properties required for modelling and stimulating the PCM in any storage systems such as thermal conductivity, enthalpy curve, phase diagram, specific heat, thermal diffusivity, and density. The thermal stability test indicated that the eutectic mixture had reliable thermal performance upon thermal cycling. Based on all these results, the MP-LA eutectic mixture is a promising material for thermal energy storage.
Tensor polarization observables ( t(20), t(21), and t(22)) have been measured in elastic electron-deuteron scattering for six values of momentum transfer between 0.66 and 1.7 (GeV/c)(2). The ...experiment was performed at the Jefferson Laboratory in Hall C using the electron High Momentum Spectrometer, a specially designed deuteron magnetic channel and the recoil deuteron polarimeter POLDER. The new data determine to much larger Q2 the deuteron charge form factors G(C) and G(Q). They are in good agreement with relativistic calculations and disagree with perturbative QCD predictions.
The purpose of this study was to investigate the effect of different commercially used dental materials (RelyX Luting Plus and Dyract Extra) mixed with either a metallic ionic solution or a colloidal ...suspension of metallic nanoparticles. Both the solution and the suspension contained a mixture of silver, copper, and lithium ions.
The metal/ion-incorporated dental materials were prepared into disk-shaped samples and tested against the growth of
. The susceptibility of bacteria against the antibacterial dental disks was tested using two methods: counting the colony-forming units per milliliter and disk diffusion (Kirby-Bauer). The incorporated materials (Dyract and Rely cement) were tested for ion release using flame atomic absorption spectroscopy.
Assessment showed efficient antibacterial activity of metal ion-incorporated Rely luting cement, exhibited by the formation of inhibition zones larger than those formed by the standard antibiotic, as well as a reduction in bacterial number of sevenfold after incubation for 24 hours. Dyract material incorporated with nanoparticles showed no significant clear zones and had no inhibiting effect on bacterial colony numbers after incubation for 24 hours. The release of silver, copper, and lithium metal ions depended on the type of both dental material and the incorporated nanoagents. The metal ion-incorporated Rely Plus cement released the highest levels of metal ions, which was attributed to its antibacterial efficiency.
Rely Plus cement incorporated with the nanoparticle suspension demonstrated high antibacterial potency, due to the release of the highest concentrations of silver, copper, and lithium metal ions. This work is the first direct comparative study of dental materials with different forms of nanomixtures (metallic nanoparticles and soluble metallic ions) and their antibacterial effects after incubation with bacterial culture for 24 hours.
A rigorous extraction of the deuteron charge form factors from tensor polarization data in elastic electron-deuteron scattering, at given values of the 4-momentum transfer, is presented. Then the ...world data for elastic electron-deuteron scattering is used to parameterize, in three different ways, the three electromagnetic form factors of the deuteron in the 4-momentum transfer range 0-7 fm^-1. This procedure is made possible with the advent of recent polarization measurements. The parameterizations allow a phenomenological characterization of the deuteron electromagnetic structure. They can be used to remove ambiguities in the form factors extraction from future polarization data.
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