Faculty Publications
Permanent URI for this communityhttps://idr.nitk.ac.in/handle/123456789/18736
Publications by NITK Faculty
Browse
20 results
Search Results
Item Drying induced shrinkage stresses of a two-dimensional rectangular brick of aspect ratio 2 is studied numerically. The drying of brick is analysed as a conjugate problem. The conservation equations for the solid are obtained using continuum approach and the Navier-Stokes equations have been solved for the flow field. An elastic model has been used to calculate the shrinkage stresses. The present unified model predicts the stress concentration at the leading edge where it is expected to be maximum due to large shrinkage. Copyright © 2000 John Wiley & Sons, Ltd.(John Wiley and Sons Ltd, Study of shrinkage stresses for drying of brick as a conjugate problem) Murugesan, K.; Seetharamu, K.N.; Aswatha Narayana, P.A.; Thomas, H.R.; Ferguson, W.J.2000Item The evaporative drying of a two-dimensional rectangular brick is studied numerically as a conjugate problem. The conservation equations for the solid are obtained using the continuum approach. The Navier-Stokes equations have been employed for obtaining the flow field and the corresponding flow solutions are used for predicting the drying behavior of the brick. The predictions of temperature and moisture content show that the leading edge dries faster compared to other sides of the solid. The full two-dimensional solutions differ considerably from the solutions based on heat and mass transfer through the boundary layers over the top surface. Average heat and mass transfer coefficients appropriate to the conjugate problem have been defined, based on constant temperature and moisture differentials between the solid and the ambient. The corresponding Nusselt and Sherwood number values indicate that analogy does not exist between heat and mass transfer, until the entire brick reaches wet bulb conditions. Free convection effects on drying are also studied for some initial period for low Reynolds number. Due to the influence of buoyant forces imparted by gravity, the overall drying rate has improved. © 2001 Elsevier Science Ltd. All rights reserved.(Elsevier Ltd, A theoretical model of brick drying as a conjugate problem) Murugesan, K.; Suresh, H.N.; Seetharamu, K.N.; Aswatha Narayana, P.A.; Sundararajan, T.2001Item A comparison of the effects of microwave versus conventional drying on the mechanical properties distribution of dried green porcelains(2008) Hemanthakumari, P.N.; Satapathy, L.N.The effect of fast microwave drying of electroporcelain insulator component was studied by determining the reliability parameter. The Weibull modulus was calculated using the three-point bend strength data of a large number of green samples which were dried using microwave energy. The results were compared with those obtained by conventional drying methods. It was observed that in most cases, microwave-dried components yielded higher Weibull modulus than their conventionally dried counterparts. A high modulus value of >15 was achieved on the microwave-dried samples. The analysis of the result was useful in understanding the fast drying process in ceramics. © 2008 The American Ceramic Society.Item An empirical model for the estimation of moisture ratio during microwave drying of plaster of Paris(2008) Ganesapillai, M.G.; Iyyaswami, I.; Murugesan, T.The drying characteristics of plaster of Paris (POP) under microwave irradiation were studied for different shapes of materials through various drying parameters like microwave power, initial moisture content, and drying time. An empirical model for the estimation of moisture ratio was developed using the drying kinetic data of POP. Further, the experimental data on moisture ratio of POP for different operating conditions were fitted with the nine basic drying model equations. Based on the observations, the constants and coefficients of the literature models were rewritten in the form of Arrhenius and logarithmic expressions considering microwave power as input variable. Fifty-eight new model expressions were derived by changing the constants and coefficients and tested using the present experimental data. From the analysis of RMSE, ?2, and EF parameters for the derived models, a suitable empirical model (Model No. 55, RMSE = 0.0874; ?2 = 0.0020; EF = 0.9999) was established to represent the present experimental data on microwave drying of POP.Item Characterization and process optimization of microwave drying of plaster of Paris(2008) Ganesapillai, M.G.; Iyyaswami, I.; Murugesan, T.The changes in the characteristics of plaster of Paris (pop) during drying operation under microwave irradiation conditions, namely surface morphology, effective moisture diffusivity, and absorption of microwave, were studied. The drying characteristics and kinetics of the process during microwave drying of plaster were studied for rectangular-faced cuboids (80 × 70 × 15, L × B × H in mm) through various drying parameters like microwave power input, initial moisture content, and drying time. Further, the experimental data on moisture ratio of plaster for different operating conditions were obtained and the optimization of the microwave drying process parameters was performed with response surface methodology (RSM) by considering all the above-said independent variables. Based on the RSM analysis, the optimum values of the process variables were obtained as: initial moisture content (A) 60%; microwave power input (B) 180 W; and drying time (C) 480 S.Item Moisture diffusivity and energy consumption during microwave drying of plaster of Paris(2010) Ganesapillai, M.G.; Iyyaswami, I.; Miranda, L.R.; Murugesan, T.The drying characteristics of plaster of paris (POP) under microwave conditions at different microwave power input, initial moisture content, sample thickness and drying time were studied. Further the experimental data on moisture ratio of POP for different operating conditions were obtained and calculations were made using nine basic drying model equations. The appropriate model with modified constants and coefficients to represent the drying kinetics of POP was found through the analysis of the statistical analysis. The effective moisture diffusivity of the drying process was also computed for different experimental conditions and a relationship between the drying rate constant and the effective moisture diffusivity was obtained. The energy consumption for microwave drying of plaster of paris at different experimental conditions were also computed. © 2010 The Berkeley Electronic Press. All rights reserved.Item Effect of Drying on the Index Properties of Lateritic Soils(2012) Sunil, B.M.; Krishnappa, H.Due to significant variation in geological and climatic conditions the characteristics of lateritic soils vary from place to place. Because of the prevailing climatic conditions, the laterites and lateritic soils of a particular region may be different from those found in other parts of the world. Some investigators report that the pretest drying has significant effect on the properties of soils. In such studies the authors associate the effect of drying on the properties of soils due to the mineralogy of soil. From this context there is a need to investigate the effect of sample preparation on lateritic soils prior to testing. In the present study lateritic soils from different sources in west coast region of India were studied to investigate the effect of drying on their index properties. Due to pretest drying it is observed from the results that there is a significant change in Atterberg limits and other properties of soils tested. These changes are attributed due to aggregation of particles. The observed changes are found to be permanent. © 2012 Springer Science+Business Media B.V.Item Influence of Drying Temperature on Three Soils Physical Properties(Springer International Publishing, 2016) Sunil, B.M.; Deepa, A.V.Changes in plasticity characteristics of three soils upon drying are examined in this paper. These changes are attributed to aggregation of particles. The key characteristic evaluated was the impact of drying temperature on the index properties, compaction characteristics and California bearing ratio. The study found the effect of drying strongly depended on soil type, mineralogy or presence of cementing agents. The observed changes are found to be permanent and the implications are that these changes may affect the field performance of test soils. © 2016, Springer International Publishing Switzerland.Item Drying of Agricultural Grains in a Multiple Porous Draft Tube Spouted Bed(Taylor and Francis Ltd. michael.wagreich@univie.ac.at, 2017) Rajashekhara, S.; Murthy, D.V.R.A multiple porous draft tube spouted bed (MPDTSB) was used to carry out drying of Ragi (Eleusine coracana), Barley, and Wheat grains. Batch experiments were conducted under varied conditions of initial moisture contents of grains, air inlet temperatures, and airflow rates. The draft tube parameters and fluid inlet sizes were also varied in the study. The results indicated that MPDTSB has the potential to be used for scale up to large-scale solids drying. In addition, two single porous draft tube spouted beds (SPDTSBs) were used for comparison with MPDTSB; the batch drying times in the MPDTSB were found to be lower when compared to those in SPDTSB under identical operating conditions. © 2017, Copyright © Taylor & Francis Group, LLC.Item Effect of working parameters on the surface integrity in cryogenic diamond burnishing of 17-4 PH stainless steel with a novel diamond burnishing tool(Elsevier Ltd, 2019) Sachin, B.; S, N.; Dupadu, D.The productivity of the components is adversely affected by the poor surface integrity characteristics as a consequence of the generation of high temperature in the burnishing zone. The abundant use of conventional lubricants causes environmental pollution and health problems. To overcome these issues, cryogenic cooling has been used across the world to reduce the temperature generated in the burnishing zone. It is well known that most of the accidents which involve aero engines have revealed that the reason for this may be due to the failure of the first stage of compressor blades. Hence aerospace material, 17-4 precipitation hardenable (PH) stainless steel can be used in aero engines to minimize the failure occurring due to foreign object damage. In the present study, the effect of cryogenic diamond burnishing on the surface integrity characteristics such as surface roughness, surface hardness, surface morphology, surface topography, subsurface microhardness, and residual stress of 17-4 pH stainless steel have been investigated with a novel diamond burnishing tool and also it has been related to dry and minimum quantity lubrication (MQL) environments. From the experimental results of diamond burnishing process, surface roughness was observed to be reduced by 33%–50%, 34%–51% and 25%–40% in the cryogenic cooling environment in contrast with MQL and dry environments. Similarly, the surface hardness improvement in a cryogenic cooling environment was found to be 5%–7%, 6%–10%, and 6%–9%, in comparison with MQL and dry environments respectively. © 2019 The Society of Manufacturing Engineers