Publications

This paper discusses about the significance of naturally occuring nano-crystalline minerals  on the adsorption and entrapment of critical metals like rare earth and rare metals of National importance. 

This study presents the development, validation, and application of a multiscale numerical model for an open thermochemical energy storage (TCES) reactor using SrBr2·6H2O as the representative reactive medium. The objective is to accurately capture and predict the coupled phenomena of heat and mass transfer occurring across two physical scales—the reactor bed and individual salt grains—during hydration and dehydration cycles. Experiments are conducted on a rectangular stainless-steel reactor filled with SrBr2·6H2O under controlled inlet air conditions. SEM images are used to estimate grain-level porosity and the particle size distribution. Grain diameters range from 0.2 mm to 4.0 mm, and porosities vary from 0.13 to 0.22 across cycles. The multiscale model is developed in MATLAB, where the bed-level routine solves conservation equations using Darcy's law and volume-averaged properties. Conversely, the grain-level routine solves unsteady diffusion-reaction equations inside the spherical salt grains. Reaction advancement modifies the grain size and the porosity dynamically, and volume-averaged source terms aid in coupling the two scales. A representative grain approach is adopted for better computational efficiency without compromising the accuracy of the results. The developed model is validated against in-house experiments and prominent literature with outlet temperature predictions, achieving R2 values of 0.93 and 0.98 for hydration and dehydration, respectively. A parametric study reveals that smaller grain sizes (0.2 mm) reduce reaction time by 47 % but increase pressure drop up to 2843 Pa. Higher energy densities (∼1.6 GJ/m3) enhance storage while increasing flow resistance. The novel framework helps evaluate TCES reactor performance with evolving material properties across different scales, and enables performance optimisation by balancing energy density, thermal output, and auxiliary power demand.

High energy density and minimal energy losses render thermochemical energy storage (TCES) systems a promising long-term solution for space heating applications. While inorganic salt hydrates are considered effective thermochemical materials, challenges such as cycling stability, agglomeration, and deliquescence during the charging and discharging processes limit their efficacy. Porous matrices, like silica gel (SiO2), present a viable alternative to address these issues. In this study, a two-dimensional numerical model for SiO2 is developed for an open TCES system and validated against in-house experimental data. A parametric analysis was conducted to examine the effects of varying inlet airflow rates and air temperature on the system's discharging performance. The numerical results exhibit the maximum temperature rise of ~ 33°C and peak discharging efficiency of ~49% for the lowest airflow rate of 0.00639 kg/s. Additionally, the highest discharging efficiency of 60.38% was observed at the highest inlet air temperature of 27°C. These findings offer valuable insights for optimizing material composition to enhance the stability and sustainability of energy storage systems.

The present study uses a three-dimensional numerical model to investigate the thermal stratification performance of vertical cylindrical thermal energy storage under simultaneous charging and discharging operations pertinent to low-temperature (below 100 ℃) industrial applications. First, the study investigates an oil-based TES using Hytherm 600 as the heat storage medium, and water circulating through the

immersed helical discharging coil serves as the heat extraction fluid. To compare the energy-harnessing features, the study considers the reverse scenario with water as the heat storage medium and oil as the discharging fluid. The charging temperature and flow rate are kept constant at 90 ℃ and 0.5 L/min, respectively. Three discharging flow rates (i.e., 0.5, 1.25, and 2 L/min) are considered to understand the realistic interplay between energy demand and supply. Results show that the water-based TES system exhibits the highest energy discharged (3733.9 kJ) and discharging efficiency (72.7%), accompanied by peak average stratification number and low energy losses to the surroundings (263.2 kJ), with the coil-side discharging (oil) flow rate of 2 L/min. However, for the oil-based TES system, the energy discharged (1343 kJ) and discharging efficiency (57%) are comparatively lower for the 2 L/min water flow rate through the discharging coil.

Multispecies ethnographies have begun to understand the sentient lives of nonhuman beings within increasingly human-dominated, ecological contexts of the Anthropocene, especially in India, where the close physical and emotional proximity of humans and macaques over centuries have led to intense interspecies behavioural exchanges and to slow, but irreversible, processes of synurbisation, wherein individual macaques have begun to adapt to urban ecologies. Drawing on our ongoing studies on the synurbisation of rhesus and bonnet macaque populations from across the country, I highlight, in this chapter, what living in altered socioecological environments might mean to both macaques and humans, and, in the process, reflect on the urban ecologies of our future.