Dixit, Ambesh

Metastable supercooled liquid phase change material (MSLPCM) is prepared by homogeneous mixing of sodium acetate trihydrate (SAT), water and ethylene glycol (EG) in 92:5:3 weight fractions, respectively. A stainless steel (SS-306) triggering disk of size 20 mm (L) × 18 mm (W) × 0.2 mm (T) is fabricated by engraving grooves on SS disk for initiating nucleation in heat pack and release of heat at the time of requirement. The PCM heat pack containing 300 g PCM and a triggering disk is fabricated using high frequency PVC sealing machine. Thermal performance of identical PCM heat pack and water pack (300 g water) is carried out inside temperature history measuring setup at 0 °C ambient temperature. The temperature of PCM heat pack and water heat pack reduces from 70 to 30 °C in 210 and 48 min, respectively at 0 °C ambient temperature. The heating time of PCM heat pack is ~4.4 times more compared to water heat packs.

Supercapacitors (SCs) are energy storage devices with high power density and robust charge/discharge life cycles. The high power density of these energy storage devices makes them attractive storage devices in conjunction with other reversible electrical energy storage devices such as batteries and conventional capacitors. The common SCs are made of nanostructured carbonous electrode materials, which are limited with their relatively lower operating window and specific energy densities. Nanostructured metal oxide based carbonous composites are widely explored to overcome carbonous SCs. Rare earth (RE) oxides such as Nd2O3, Y2O3, and Eu2O3 are used in conjunction with carbonous/conducting polymers matrix for high specific density and operating voltage supercapacitors. The high band gap of RE oxides assists in achieving higher operating voltage window. The article will review the current status of RE oxide based supercapacitors and their physical properties in conjunction with underlying physical principles.

The concentrated solar thermal technologies (CST) are versatile in view of their multi-faceted applications, such as, process heat, cooling, and electricity generation. These are of line and point-focusing types with the later having much higher flux concentration (in Suns). This allows achieving a temperature in excess of 1200 K using, for instance, the open volumetric air receiver (OVAR). Such a high temperature is useful for applications, like the one which is developed at IIT Jodhpur, namely the solar convective furnace for heat treatment of aluminum. This requires a temperature of up to 750 K in the first phase of development. Thus, a suitable solar selective coating withstanding such a high temperature and having a thermal conductivity close to the base material for operating in an open atmosphere is desirable. Because of its atmospheric exposure, air and dust-induced degradation is inevitable, which may lead to its failure. These challenges are to be addressed for adapting such high-temperature CST technologies in arid deserts of India, the Middle-East, and Africa. In view of such challenges, the following details and foreseen developments are discussed in the paper: (a)design of OVAR including various sub-components;(b)flow-stability and the effect of heat-flux distribution on an absorber pore;(c)the developed coating and its characterization for OVAR.

First principle calculations are carried out to investigate the ground state electronic and magnetic properties of G-type antiferromagnetic (AFM) LaCrO3 compound in orthorhombic phase. The orthorhombic LaCrO3, a distorted GdFeO3 - type perovskite exhibits AFM transition at ~290 K. Additionally; this system shows weak ferromagnetism at room temperature, in conjugation with its semiconducting properties. In this paper, we will discuss the onset of weak ferromagnetism and electronic properties of LaCrO3, implementing generalized gradient approximation for exchange correlation potential. We present results for electronic structure and density of states, including the effect of onsite Coulomb interaction and non-collinear arrangement of Cr³⁺ magnetic ions in G-type AFM geometry. © (2012) Trans Tech Publications, Switzerland.

Solar selective coatings (SSC) are integral part of the receiver in any concentrated solar thermal system for efficient conversion of incident solar energy into thermal energy. The most common solar thermal systems are based on parabolic trough collectors, which are operating at 350 °C. Thus, the absorber coating should be robust and efficient to operate at such temperatures without any degradation. There are limited such solar selective coatings and very few are commercially available. These are cermet based structure and are stable at high temperature in vacuum. These structures are prone to chemical reaction in open-air condition, which results in degraded optical performance of SSC structures. Thus, there are issues and challenges in SSCs, especially for higher operating temperatures, which is essential to realize the higher efficiency of solar thermal systems. The work is focusing on such constraints towards realizing high temperature solar selective coatings.