Ashok Misra

PARAMETRIC OPTIMIZATION AND PERFORMANCE ANALYSIS OF A REGENERATIVE ORGANIC RANKINE CYCLE USING LOW-GRADE WASTE HEAT FOR POWER GENERATION

This paper presents an analysis of regenerative Organic Rankine Cycle (ORC), based on the parametric optimization, using R-12, R-123, R-134a, and R-717 as working fluids superheated at constant pressure. A computer program has been developed to parametrically optimize and compare the system and second law efficiency, irreversibility rates of the system and their components, availability ratio, work output, system mass flow rate with increase in turbine inlet temperature under different heat source temperature conditions. The calculated results reveal that selection of a regenerative ORC during superheating using R-123 as working fluid appears to be a choice system for converting low-grade waste heat to power.

Can a stress alone applied to a demagnetized ferromagnetic specimen produce any magnetization

Abstract This paper attempts to investigate whether a stress alone applied to a demagnetized ferromagnetic specimen can produce any magnetization. It has been concluded that the complex dislocation configuration during the necking and just prior to tensile fracture, is capable of abruptly orienting the magnetization vectors producing a net resultant component along the axial direction of the circular specimen which gives rise to the observed generation of the high transient magnetic field.

Electromagnetic radiation during plastic deformation under unrestricted quasi-static compression in metals and alloys

Abstract Intermittent electromagnetic radiation (EMR) emissions from metals and alloys during deformation under unrestricted quasi-static compression are reported in this paper. The end surface conditions of the compressing platens, whether lubricated or unlubricated, influence the EMR emission characteristics. The EMR emissions under compression show shape anisotropy. The first EMR emission invariably occurs near the yield. The EMR emission characteristics are also influenced by the crystal structure. During axial compression, dead metal zones formed on the top and bottom portions of the specimens possibly generate a climbing motion of edge dislocations in the radially outward mid-regions. During the climbing motion, these edge dislocations form accelerated electric line dipoles and emit electromagnetic radiation. These EMR emissions can be used to evaluate the degree of damage in metallic components under compression.

Some Experimental and Theoretical Investigations on Fire Retardant Coir/Epoxy Micro-Composites

This article reports some experimental and theoretical investigations on fire retardant coir/epoxy micro-composites. The coir fiber is treated with saturated bromine water for increasing the electrical properties and then mixed with stannous chloride solution for improving the fire retardant properties. Only 5% (approximately) of fire retardant filler reduces the smoke density by 25% and the LOI value increases to 24%. The mechanical properties of the coir/epoxy micro-composites are not affected much after incorporation of filler. Flexural strength and flexural modulus of the NET increases tremendously compared to NEU and NE. Multiquadric radial basis function (MQRBF) method is applied for static and dynamic analysis of coir/epoxy micro-composite plate under uniformly distributed load. Damping behavior and natural frequencies are observed in NE, NEU, and NET. MQRBF is applied for spatial discretization and Newmark implicit scheme is used for temporal discretization. The discretization of the differential equations generates greater number of algebraic equations than the unknown coefficients. The multiple linear regression analysis, which is based on the least square error norm, is employed to obtain the coefficients. Simple supported and clamped boundary conditions are considered for verification of present results and they are compared with other existing analytical methods.

Effect of rate of deformation on electromagnetic radiation during quasi-static compression of sintered aluminium preforms

Abstract This paper presents some experimental results on the intermittent electromagnetic radiation (EMR) characteristics of sintered aluminium powder preforms under quasi-static compression. The stress level within the gross elastic limit and yielding of the partially compact preforms at which first EMR emission is observed, bears a distinct parabolic relation with the rate of compressive deformation. These observations can be developed into a new technique to detect the compactness of sintered metal powder preforms for industrial components. Further, each successive intermittent EMR emission at all rates of deformation requires increasing incremental strain energy during progressive plastic deformation. The electromagnetic energy release rate decreases sharply as the rate of deformation is increased and then attains a more or less constant value at higher rates of deformation. These results appear significant in understanding the mechanism of plastic deformation in metal powder preforms at the microscopic level, not yet reported in the literature.

Assessment of grain size and lattice parameters of titanium alloy through electromagnetic emission technique

Effects of variation in grain size and lattice parameters at elevated temperatures on the electromagnetic radiation (EMR) during failure under tension of ASTM B265 Grade 2 titanium have been investigated. The EMR is observed to be anisotropic in nature. The EMR amplitude decreases with increase in grain size. The magnitude of variation depends upon the processing history of specimens. The EMR amplitude decreases exponentially with lattice parameters in titanium while the decrease in EMR frequency is polynomial in nature. The experimental results are in close agreement with the theoretical predications presented in this paper. A comparison with the results reported earlier shows that the nature of EMR responses with lattice parameters is independent of metal crystal structure. These investigations lead to a new technique for the assessment of grain size and lattice parameters in metals.

Correlation of plastic deformation induced intermittent electromagnetic radiation characteristics with mechanical properties of Cu–Ni alloys

Abstract This paper presents experimental results on intermittent electromagnetic radiation during plastic deformation of Cu–Ni alloys under tension and compression modes of deformation. On the basis of the nature of electromagnetic radiation signals, oscillatory or exponential, results show that the compression increases the viscous coefficient of Cu–Ni alloys during plastic deformation. Increasing the percentage of solute atoms in Cu–Ni alloys makes electromagnetic radiation strength higher under tension. The electromagnetic radiation emission occurs at smaller strains under compression showing early onset of plastic deformation. This is attributed to the role of high core region tensile residual stresses in the rolled Cu–Ni alloy specimens in accordance with the Bauschinger effect. The distance between the apexes of the dead metal cones during compression plays a significant role in electromagnetic radiation parameters. The dissociation of edge dislocations into partials and increase in internal stresses with increase in solute percentage in Cu–Ni alloys under compression considerably influences the electromagnetic radiation frequency.

Comparative performance study of different configurations of organic Rankine cycle using low-grade waste heat for power generation

ABSTRACT This paper aims at analyzing the feasibility of a waste heat recovery power generation plant based on parametric optimization and performance analysis using different organic Rankine cycle configurations and heat source temperature conditions with working fluid R-12, R-123, R-134a, and R-717. A parametric optimization of turbine inlet temperature(TIT) was performed to obtain the irreversibility rate, system efficiency, availability ratio, turbine work output, system mass flow rate, second-law efficiency, and turbine outlet quality, along the saturated vapor line and also on superheating at an inlet pressure of 2.50 MP in basic as well as regenerative organic Rankine cycle. The calculated results reveal that selection of a basic organic Rankine cycle using R-123 as working fluid gives the maximum system efficiency, turbine work output, second-law efficiency, availability ratio with minimum system irreversibility rate and system mass flow rate up to a TIT of 150°C and appears to be a choice system for generation of power by utilizing the flue gas waste heat of thermal power plants and above 150°C the regenerative superheat organic Rankine cycle configuration using R 123 as working fluid gives the same results.