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    Experimental and theoretical investigations on the cyclic operation of TSA cycle for air dehumidification using packed beds of silica gel particles
    (Elsevier Ltd, 2013) Ramzy K, A.K.; Kadoli, R.; Ashok Babu, T.P.
    Dehumidification using desiccant beds provide a good alternative for the conventional vapor compression cooling system. Desiccant material in the desiccant dehumidification system should undergo both adsorption and desorption processes. In the present work, experimental tests have been carried out for thermal swing adsorption (TSA) cycle utilizing two packed beds of silica gel spherical particles. The pseudo gas side controlled (PGC) mathematical model has been presented for predicting the cycle performance. The mathematical model has been validated using the experimental results. The root mean square of errors ranges from 1.15% to 9.03% for the exit air humidity ratio and from 1.08% to 9.68% for exit air temperature. The dynamics of desiccant bed during the cyclic operation has been investigated numerically. In addition, it has been found from the parametric study that the cycle efficiency is maximum for a regeneration temperature of 90-95°C when the bed length varies from 50 to 300mm and for desiccant particle diameter ranging from 2 to 5mm. A sensible cooling for the process air before undergoing the dehumidification period is recommended for increasing the cycle efficiency and the dehumidification time which is an added advantage. © 2013 Elsevier Ltd.
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    Colorimetric and fluorometric turn-on sensor for selective detection of fluoride ions: Sol-gel transition studies and theoretical insights
    (Royal Society of Chemistry, 2018) Pangannaya, S.; Mohan, M.; Trivedi, D.R.
    A new organic receptor R1 based on a naphthyl unit covalently linked to a long alkyl chain has been designed, synthesized and characterized by standard spectroscopic techniques. The colorimetric response of receptor R1 from colorless to a pale yellow color and blue fluorescence emission in the presence of F- ions revealed its selective sensing ability in the solution phase. UV-Vis titration, fluorescence titration and 1H NMR titration studies confirmed the formation of the R1-F- complex. Receptor R1 formed a stable gel in DMSO and was confirmed through the standard heating-and-cooling method. Addition of F- ions resulted in disruption of the gel forming a solution that exhibited blue fluorescence emission. The binding constant of the R1-F- complex was found to be of the order of 5.9 × 105 M-1. DFT studies revealed the formation of the receptor-anion complex agreeing well with the experimental results. The detection limit was calculated and found to be 0.8 ppm, implying the potential for application of receptor R1 in environmental applications. © 2018 The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.
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    Exploring the relationship between LST and land cover of Bengaluru by concentric ring approach
    (Springer Science and Business Media Deutschland GmbH info@springer-sbm.com, 2020) Govind, N.R.; Ramesh, H.
    The present study aims at investigating the impact of land cover features in enhancing or mitigating Land Surface Temperature (LST) in a semi-arid tropical metropolitan city of Bengaluru, India. Spatial distribution of LST and land cover types of the area were examined in the circumferential direction, and the contribution of land cover classes on LST was studied over 28 years. Urban growth and LST were modelled using Landsat and MODIS data for the years 1989, 2001, 2005 and 2017 based on the concentric ring approach. The study provides an efficient methodology for modelling and parameterisation of LST and urban growth by fitting an inverse S-curve into urban density (UD) and mean LST data. In addition, multiple linear regression models which could effectively predict the LST distribution based on land cover types were developed for both day and night time. Based on the analysis of remotely sensed data for LST, it is observed that over the years, urban core area has increased circumferentially from 5 to 10 km, and the urban growth has spread towards outskirts beyond 15 km from the city centre. As urban expansion occurs, the area under the study experiences an expansive cooling effect during day time; at night, an expansive heating effect is experienced in accordance with the growth in UD in the suburban area and outskirts. The regression models that were developed have relatively high accuracy with R2 value of more than 0.94 and could explain the relationship between LST and land cover types. The study also revealed that there exists a negative correlation between urban, vegetation, water body and LST during day time while a positive correlation is observed during night. Thus, this study could assist urban planners and policymakers in understanding the scientific basis for urban heating effect and predict LST for the future development for implementing green infrastructure. The proposed methodology could be applied to other urban areas for quantifying the distribution of LST and different land cover types and their interrelationships. © 2020, Springer Nature Switzerland AG.
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    Experimental study on failure and fracturing attributes of granite after thermal treatments with different cooling conditions
    (Elsevier B.V., 2022) Srinivasan, V.; Hasainar, H.; Singh, T.N.
    Thermal damage is one of the fundamental mechanisms affecting the stability of rocks encountered in many deep geo-engineering ventures such as nuclear waste isolation, geothermal extraction etc. In the present study, the findings on influence of heating and subsequent cooling conditions on the fracturing and mechanical behaviour of an Indian granite are discussed. The granite samples from Jalore region of India were heated from room temperature to 600 °C followed by slow cooling and water quenching treatments. It was observed that rapid cooling through quenching had a greater impact on strength, elastic properties than slow cooling rate. Moreover, a drastic shift in terms of fracturing thresholds was witnessed, as a function of both temperature and sudden thermal shock experienced by rock at higher cooling rate. The simultaneous AE monitoring results suggested an early crack damage at higher thermal regimes. With help of microscopic observations, it was observed that inter-granular crack boundaries widened with increasing thermal damage experienced by minerals under both cooling conditions. However, the fracturing process was intense under rapid cooling treatment due to the invasion of water due to quenching which accelerated severe intra-crack growths, especially at higher thermal stress because of the rapid cooling rate than the slow cooling. The increased intensity of thermal cracks with temperatures and with variation in cooling rate was inferred as the primary reason for decay of rock characteristics. This was very well supplemented by decay in strength properties and changes in fracturing attributes of the tested granite as inferred from acoustic monitoring. © 2022
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    Sorption–desorption characteristics of dried cow dung with PVP and clay as composite desiccants: Experimental and exergetic analysis
    (Elsevier Ltd, 2023) Dasar, S.R.; Boche, A.M.; Yadav, A.K.; Anish, S.
    The present study investigates the sorption and desorption characteristics of a natural composite desiccant based on dried cow dung (DCD). Polyvinyl Pyrrolidone (PVP) and clay are used as binders with DCD. The moisture uptake capacity of composite desiccants is measured with an isotherm experiment under different DCD to binder ratios. Based on their isotherms, composite desiccants are chosen for characteristic study under different humid conditions and validated with available literature data. Brunauer–Emmett–Teller (BET) and Barrett–Joyner–Halenda (BJH) analyses are carried out to understand the physical properties of DCD, DCD+PVP (3:1) and DCD+Clay (3:1). Total heat load reduction, exergy efficiency and power required for these dehumidification systems are calculated for different inlet conditions. Desorption characteristics are tested at 328 K and 6% RH. Results show the maximum moisture uptake capacity of DCD and DCD+PVP as 14.42 and 14.72 g/100 g, respectively. The maximum exergy efficiency of the DCD+PVP dehumidification system is found to be 55%. Desorption time for DCD+PVP desiccant is 17 min, which is 4 and 2 min higher compared to DCD, and DCD+Clay, respectively. With this experimental study, it is concluded that the DCD+PVP has the potential to become an alternative to chemical desiccants based on their exergy efficiency and moisture uptake capacity. © 2022 Elsevier Ltd
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    Insulator-to-metal-like transition in thin films of a biological metal-organic framework
    (Nature Research, 2023) Sindhu, P.; Ananthram, K.S.; Jain, A.; Tarafder, K.; Ballav, N.
    Temperature-induced insulator-to-metal transitions (IMTs) where the electrical resistivity can be altered by over tens of orders of magnitude are most often accompanied by structural phase transition in the system. Here, we demonstrate an insulator-to-metal-like transition (IMLT) at 333 K in thin films of a biological metal-organic framework (bio-MOF) which was generated upon an extended coordination of the cystine (dimer of amino acid cysteine) ligand with cupric ion (spin-1/2 system) – without appreciable change in the structure. Bio-MOFs are crystalline porous solids and a subclass of conventional MOFs where physiological functionalities of bio-molecular ligands along with the structural diversity can primarily be utilized for various biomedical applications. MOFs are usually electrical insulators (so as our expectation with bio-MOFs) and can be bestowed with reasonable electrical conductivity by the design. This discovery of electronically driven IMLT opens new opportunities for bio-MOFs, to emerge as strongly correlated reticular materials with thin film device functionalities. © 2023, The Author(s).
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    State-of-the-art assessment-based review of boiling heat transfer and friction factor correlations for NH3–H2O, NH3–LiNO3 and NH3–LiNO3–H2O mixtures in a plate heat exchanger
    (Nature Research, 2025) Chauhan, V.K.S.; Sathyabhama, A.; Hegde, R.N.
    The increasing demand for energy-efficient and environmentally sustainable cooling technologies has led to a renewed focus on ammonia and lithium nitrate-based absorption refrigeration systems, particularly those utilizing Plate Heat Exchangers (PHEs). Despite their importance, reliable predictive models for boiling heat transfer and frictional pressure drop in PHEs using ammonia and lithium nitrate mixtures, such as NH3–LiNO3 and NH3–LiNO3–H2O, remain limited and often suffer from structural deficiencies. This study provides a comprehensive evaluation of existing correlations for boiling heat transfer and friction factor in PHEs, specifically focusing on ammonia-based mixtures (NH3–H2O, NH3–LiNO3, and NH3–LiNO3–H2O). More than 20 correlations for boiling heat transfer coefficient and friction factor were critically analysed and adjusted to account for the unique thermophysical behaviors of multi-component salt mixtures. The study reveals that many correlations fail to accurately predict boiling heat transfer in NH3–H2O mixtures due to inadequate sensitivity to heat flux. Scaling these correlations led to notable improvements in prediction accuracy, underlining the significance of appropriate scaling for different PHE configurations. Additionally, the study validates the assumption that lithium nitrate remains in the liquid phase in NH3–LiNO3 and NH3–LiNO3–H2O mixtures, supporting its exclusion from latent heat calculations. Friction factor correlations that include positive exponents for Reynolds and Weber numbers were found to be structurally inconsistent, resulting in inaccurate predictions. The analysis further highlights that many correlations are overly empirical or based on narrow experimental conditions, limiting their applicability to diverse heat exchanger geometries. A key contribution of this work is the unique visual comparison of the correlations, providing a detailed depiction of their structural characteristics and offering more precise insights than those available in previous studies. © The Author(s) 2025.