Faculty Publications
Permanent URI for this communityhttps://idr.nitk.ac.in/handle/123456789/18736
Publications by NITK Faculty
Browse
5 results
Search Results
Item Experimental and theoretical study on dehumidification potential of clay-additives based CaCl2 composite desiccants(Elsevier Ltd, 2018) Hiremath, C.R.; Kadoli, R.; Katti, V.V.Transported clay suitable for pot making is used as desiccant carrier. Additives like saw dust and horse dung are considered in particle preparation. Particles nearly spherical in shape are prepared manually and are dried under shadow and subsequently the particles are dried at different temperatures. These burnt particles are characterized for pore volume and surface area. The BET test reveals that clay particles subjected to 500 °C possess higher pore volume but clay-horse dung particles exhibit higher surface area. Heat treated particles of clay with additives are impregnated with CaCl2 solution of 50% concentration. The ratio of desiccant water content to surrounding layer water content varies from 14.09 to 75.34 for CaCl2 based composite desiccants. One dimensional PGC mass transfer model for process air through burnt clay – additives - CaCl2 desiccant bed is adopted. The RMSE of measured and predicted results for reduction of moisture content from the process air by composite desiccant beds are in the range of 3.26–13.2%. © 2017 Elsevier LtdItem Experimental analysis of low-temperature grain drying performance of vertical packed clay and clay-additives composite desiccant beds(Springer, 2021) Hiremath, C.R.; Kadoli, K.A laboratory model of a forced circulation desiccant based green pea drying system operating in an open-loop is constructed and tested. The green pea drying process is divided into two stages involving dehumidification by the desiccant bed and green peas drying by dehumidified process air. Removal of moisture from the process air has been achieved by vertical packed composite desiccant beds. The composite desiccant used are heat treated clay with CaCl2 being impregnated and clay with additives like horse dung and sawdust, again being heated, treated and later impregnated with CaCl2. The green peas were dried for a process time of one hour. The drying was quite sharp during the initial process time of 500 s and from then onwards proceeded at a constant rate. For the identical bed masses, The performance of heat treated clay-additives based beds in moisture reduction and enhancement in enthalpy of process air is higher. The experimental study reveals the average heat content of air entering the dryer is 1.46, 2.46 and 2.38 kJ for heat-treated clay-CaCl2, clay-horse dung-CaCl2 and clay-sawdust-CaCl2 composite desiccant beds of 700 g mass. © 2021, Indian Academy of Sciences.Item Adsorption and desorption through packed and fluidized clay-based composite desiccant beds: a comparison study(Springer Science and Business Media Deutschland GmbH, 2022) Hiremath, C.R.; Kadoli, R.The present study considers the composite desiccant employing horse dung, sawdust with clay and later impregnating CaCl2 into the host material. The microscopic and spectroscopic experimental methods such as scanning electron microscope (SEM) and X-ray diffraction (XRD) were used to characterize the composite desiccants. The specific heat (Cp) quantification reveals higher values for clay-additives composite desiccants with lower pore volume and larger grain sizes, whereas lower values for clay composite desiccants with higher pore volume and smaller grain sizes. Adsorption–desorption experiments for moisture removal and addition are conducted in a vertical column in static and fluidized states. The desiccant beds are subjected to an initially set value of process air velocity, relative humidity, temperature and mass of bed. Moisture removal capacity, moisture addition capacity and mass transfer coefficient are the parameter indices adopted to measure the heat and mass transfer characteristics of vertical packed and fluidized bed comprising clay-additives-CaCl2 composite desiccants. Comparing packed and fluidized beds, a higher surface area of bed in fluidization improves dehumidification performance and results in higher desorption rates. Experimental results confirmed that clay and clay-additives-based desiccants have desired adsorption–desorption characteristics of a suitable desiccant. The interesting advantage of fabricated clay and clay-additives-based composite adsorbents is that the air exits the desiccant bed at a lower temperature, saving cooling energy requirements of sorption-based systems. © 2022, The Author(s), under exclusive licence to The Brazilian Society of Mechanical Sciences and Engineering.Item 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 LtdItem Experimental study on sorption–desorption characteristics of natural composite desiccant with metal embedment(Elsevier Ltd, 2023) Dasar, S.R.; Anish, S.; Kadoli, R.; Yadav, A.K.The present study investigates the effect on total moisture sorption, moisture sorption rate, moisture desorption rate, and reduction in the temperature of dehumidified air of metal-embedded natural composite desiccants (MENCDs), which can be used in dehumidification systems. A natural composite desiccant, in which the unutilized portion of the spherical desiccant material is replaced with a metallic ball, is proposed. Stainless steel balls with a diameter of 4.75 and 6.35 mm are used to make different thickness ratios (TR = 1, 0.525, and 0.365) of MENCDs. The natural composite desiccant is prepared from dried cow dung and polyvinyl pyrrolidone with a ratio of 3:1. Experiments are conducted to find the optimum thickness ratio of MENCDs. The total moisture sorption, moisture sorption rate, total heat load reduction, and exergy efficiency of these dehumidification systems are investigated under different relative humidities (RH = 65% to 85%), and at a constant temperature and velocity. Desorption characteristics are tested under 328 K and 5% RH. The total moisture sorption of MENCDs with a TR of 0.365 is found to be 11.84 g/100 g, which is 17% higher compared to natural composite desiccants (i.e., TR = 1) at 85% RH, whereas, the total moisture sorption rate is 0.4 g/100 g⋅min, which is 20.57% higher for TR of 0.365 compared to TR = 1. Moisture desorption rate for TR = 0.365 is 16.66% higher compared to TR = 1. The average exergy efficiency of these systems is 60%. The average exergy efficiency of these composite desiccants with a TR = 0.365 is 9.6% higher compared to TR = 1. The average total heat load reduction for composite desiccants with a TR = 0.365 is 24% higher compared to TR = 1. The experimental study shows that the MENCDs will help to increase total heat load reduction, sorption and desorption rate, and total moisture sorption of dehumidified air with optimum thickness ratio for enhanced utilization of a composite desiccant for dehumidification systems. © 2023 Elsevier Ltd