• Energy Research

Abstract This paper focus on the study of peritectic compound Li4(OH)3Br for thermal energy storage in solar power applications. A thoroughly characterization of Li4(OH)3Br as storage material has been performed by measuring transition temperatures (280–289 °C), enthalpies of transition (247 J/g), specific heats (c.a. 1.68 J/g/K in solid, 2.52 J/g/K in liquid) and thermal conductivity (0.47 W/m/K at room temperature). The effect of the synthesis conditions on the storage properties has been investigated as well. It is concluded that neither the cooling rate applied during the synthesis stage nor the type of atmosphere used (ambient air and protective argon atmosphere) has an influence on the material's performance. The stability of the material to thermal cycling has also been analysed, showing good cycling stability. Moreover, particular attention is paid to the elucidation of mechanisms of formation of Li4(OH)3Br. It is shown that Li4(OH)3Br needs neither the presence nor contact with the pro-peritectic phase to form. It nucleates and grows directly from the melt so as pure-phase Li4(OH)3Br final microstructure is achieved. An attempt to enhance the storage capacity of the material by addition of different types of carbon nanoparticles has been carried out. Assets of Li4(OH)3Br as storage materials for high-pressure DSG solar power plants have been assessed through comparison with reference material NaNO3. Main advantages of Li4(OH)3Br are higher volumetric latent heat storage capacity (+54%) and lower volume changes during phase transitions (3% vs. 11%), which would translate into smaller storage tanks (−33%), lower size heat exchangers and longer lifetime.

A two-dimensional model is built to analyze the coupled heat and mass transfers occurring in the zeolite 13X - water pair within a closed storage system. The proposed model consists of nonlinear coupled differential partial equations, is robust and solved for entire cycles under extreme conditions using the Gear method. The results match observations for a large set of adsorber dimensions even under extreme solicitations. They apply to both adsorption and desorption dynamics, allow energetic predictions and can be helpful to improve design and management of storage systems for building applications. (C) 2014 Elsevier Ltd. All rights reserved.

A new method based on the thermal quadrupoles technique for heat transfer modelling in multilayered slabs with heat sources is proposed. Classical thermal quadrupoles use hyperbolic functions and numerical problems occur according to the argument value that depends on thermophysical and geometrical properties as well as characteristics times. We propose a new formulation based on exponential function with negative argument. Using this formulation in the classical equivalent impedance network allows to compute efficiently the thermal behaviour of multilayered slabs with internal heat sources whatever the time and the thermophysical properties. This approach is applied in order to simulate heat transfer in three different multilayered materials with heat sources. These simulations show the capability of such a methodology to simulate time and space multiscale heat diffusion problems.

Abstract In this study, the LiBr/LiOH phase diagram and the key related thermodynamic properties of its specific compounds were theoretically and experimentally estimated (by thermodynamic modeling and differential scanning calorimetry experiments, respectively) and compared with previously reported results. The peritectic compound Li4Br(OH)3 was identified as a highly promising candidate for heat storage applications at around 300 °C, mainly because of its outstanding energy density. As a precaution, the two limiting cases of thermodynamic solidification simulations (equilibrium and Scheil–Gulliver cooling conditions) were considered to confirm the relevance of synthesizing and experimentally studying this new potential heat storage material. After many tests and adjustments, a suitable synthesis protocol was developed and validated for characterizing the Li4Br(OH)3 compound using the X-ray powder diffraction technique. Preliminary thermal analysis was also performed for the successfully synthesized peritectic compound to confirm its high potential as a heat storage material. Our results indicate that it would be useful to comprehensive analyze the thermophysical properties of this material to assess its capacity for utilization in thermal energy storage applications.

Coupling optical and thermal properties of a terahertz (THz) thermal converter based on the Seebeck effect provides an unsupplied room-temperature measuring device dedicated to THz power metrology. Performance characteristics such as broadband response (0-30 THz), high sensitivity (<25 μW·Hz(-0.5)), and the possibility to develop an internal absolute self-calibration estimated at 9.93 W·V(-1) are reported. Advantages and drawbacks of this THz powermeter are discussed.

This work focuses on an experimental study of the influence of e-liquid composition on the mass of vaporized e-liquid after standardized emission generation using a U-SAV (Universal System for Analysis of Vaping) vaping machine. All the experiments were based on the use of a Cubis 1Ω clearomiser and on the standard protocol for electronic cigarettes emission generation. Currently, there is no standardized method available to calibrate the emission generations of electronic cigarettes. Since the e-liquid compositions are not always known, we propose a simple, practical, effective, and fast method of emission generation calibration. Therefore, this paper examines a major issue in this new and constantly evolving field, allowing the validation of the emission generation results. To our knowledge, this method is a novelty in our discipline and could be easily developed in laboratories. Pure propylene-glycol, glycerol, ethanol, and water and their mixtures (20 e-liquids) were tested as reference materials, allowing an e-liquids benchmarking and the characterization of 800 commercial e-liquids (with known and unknown compositions) at a fixed power and for one inhalation profile (3 s puff duration and 55 mL of puff volume). The influence of ethanol and/or water addition in the e-liquid was characterized.