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Abstract
In high pressure calorimetry the pressure change is used to obtain the desired phenomenon (i.e. phase change) at constant temperature. Two high pressure calorimeters have been developed to measure the latent heat of fusion of pure water (hexagonal ice-type I) at subzero temperature. Both calorimeters used a constant pressurisation rate produced with a high pressure pump driven by a step motor. The first calorimeter was a single cell calorimeter where mercury acted as the pressurisation fluid, while the second one was differential (two cells) and was pressurised with pentane. Both calorimeters gave high accuracy data of latent heat of fusion of pure water, which were determined taking into account that either the fluid used to pressurise or the pressurisation rate affected the calorimetric signal.
technology. There are numerous ways to implement this technology, including storing energy via a thermochemical process and using sensible and latent heat [ 4 ]. Phase Change Materials (PCMs) are used in the Latent Heat Storage (LHS) system [ 5 ]. Studies on
/paraffin increased with the mass fraction of Al 2 O 3 nanoparticles. Hong et al. [ 15 ] added the encapsulated phase-change nanoparticles into a single-phase liquid to enhance its heat transfer property. It showed that the heat-transfer coefficients of
. During the material phase change from solid to liquid or from liquid to gases, some heated energy will be absorbed for storage and vice versa. Two main components are required to utilize solar energy: collector units and storage units. Both components are
Introduction The energy deficiency and environmental pollution during the energy utilization prompt the utilization of clean energy, such as solar, wind, and cheap power. The energy storage technology with phase change material
latent heat of melting, is a promising kind of high temperature phase change materials. Basic thermo physical properties of nitrate salts mixture at different temperature, such as specific heat, thermal conductivity, density, dynamic viscosity and so on
Abstract
The reproducibility of the phase changes at 533–543, 573–593K and 603–623 K in the system CuCl2−KCl was investigated by DTA analysis, supplemented with röntgenographic analysis. Conclusions were drawn in connection with a liquid melt and the solid state of the system.
Abstract
One of the greatest challenges in the application of organic phase change materials (PCMs) is to increase their thermal conductivity while maintaining high phase change enthalpy. 1-Tetradecanol/Ag nanowires composite PCM containing 62.73 wt% (about 11.8 vol%) of Ag nanowires showed remarkably high thermal conductivity (1.46 W m−1 K−1) and reasonably high phase change enthalpy (76.5 J g−1). This behavior was attributed to the high aspect ratio of Ag nanowires, few thermal conduct interfaces, and high interface thermal conductivity of Ag nanowires in the composite PCM. These results indicated that Ag nanowires might be strong candidates for thermal conductivity enhancement of organic PCMs.
Abstract
A BET thermodynamic model and its recently modified version were applied to predict the phase diagrams of the systems NH4NO3–LiNO3–H2O and NaNO3–LiNO3–Mg(NO3)2–H2O, in which two eutectic points were found with melting point at temperatures between 15 °C and 25 °C. Simple experiments were designed to measure the exothermal and endothermal behavior of the predicted phase change materials. The experimental results showed that the theoretically predicted materials possess excellent exothermal and endothermal behavior at room temperatures. Besides, the fusion and solidification heats of the predicted phase change materials were measured.
Abstract
This article is dedicated to develop an experimental approach for directly visualizing the global freezing phase change behavior of micro liquid droplets. The infrared (IR) thermograph was proposed to image the basic solidification phenomena of droplet and to acquire its temperature variations during the transient process. In particular, the volumetric recalescence event, regarded as initiation of freezing, was revealed by IR images for the first time. Preliminary results demonstrated that the involved temperature transition due to release of the latent heat can be accurately characterized by evident color break in IR images. Further, experiments were also performed simultaneously on three kinds of droplets made of pure water, dimethylsulfoxide (DMSO) and nano liquid to grasp more precise temporal and spatial temperature distribution. Types of the occurring solidification and the initial frozen volume produced from the recalescence were generally discussed. The IR monitoring method suggests a straightforward way for detecting the freezing phase change activity and its temperature evolution at micro scale.
