Performance of Functionally Graded Exponential Annular Fins of Constant Weight

The present work aims at investigating the performance of exponential annular fins of constant weight made of functionally graded materials (FGM). The work involves computation of efficiency and effectiveness of such fins and compares the fin performances for different exponential profiles and grading parameters, keeping the weight of the fin constant. The functional grading of thermal conductivity is assumed to be a power function of radial co-ordinate which consists of parameters, namely grading parameters, varying which different grading combinations can be investigated. Fin material density is assumed to be constant and temperature gradient exists only along the radial direction. The convective coefficient between the fin surface and the environment is also assumed to be constant. A general second-order governing differential equation has been derived for all the profiles and material grading. The efficiency and effectiveness of the annular fin of different geometry and grading combinations have been calculated and plotted and the results reveal the dependence of thermal behavior on geometry and grading parameter. The effect of variation of grading parameters on fin efficiency and effectiveness is reported. The results are provided in the form of 2-D graphs, which can be used as design monograms for further use

AN INVESTIGATION OF STRESSES AND DEFORMATION STATES OF CLAMPED ROTATING FUNCTIONALLY GRADED DISKS

The present study deals with the linear elastic analysis of variable thickness rotating disks made of functionally graded materials (FGMs) by the finite element method. The disks have radially varying material properties according to an exponential law, which is achieved by the element based grading of the material properties on the meshed domain. The results are reported for three types of thickness profiles, namely, uniform, linearly varying and concave thickness, having their mass constant. The disks are subjected to the clamped boundary condition at the inner surface and the free boundary condition at the outer surface. The obtained results show that in a variable thickness rotating disk, deformation and stresses are less as compared to the uniform thickness disk

Thermodynamic analysis of diesel engine using producer gas as secondary fuel

Paper presented to the 10th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Florida, 14-16 July 2014.The proposed work reports a combustion model for a dual fuel CI engine for Diesel cycle and Dual cycle. The work then analytically examines the performance of a CI engine with the minimum use of diesel as primary fuel, with producer gas as secondary fuel. The performance has been analysed for work output and thermal efficiency. The combustion model has been developed for ideal diesel engine, diesel-producer gas engine with diesel as primary fuel. The combustion models have been simulated using MATLAB® codes. The specifications of a standard CI engine have been used for numerical calculations. The equation of state in each process in the cycles has been critically analysed based on laws of thermodynamics. The performance analysis shows that, in a diesel-producer gas engine, thermal efficiency increases and work done decreases as the percentage of diesel supplied during combustion process decreases. Also, the addition of producer gas in a dual-fuel (Diesel-Producer gas) engine allows the engine to run over a lower range of maximum temperature of the cycle which reduces the chances of Nox formation.dc201

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

A PMV-PPD model based study of thermal comfort in Low-Income Group house in Chhattisgarh

People tend to maintain symmetry between comfort and economy while choosing essential commodities needed in their life. Families buy a house which may offer comfort condition, but at minimum in term expenses of energy throughout a life. Thus, it is most important to erect a house to provide comfortable condition and moderate the lifetime expenditure by saving energy consumption. Sensation of thermal comfort varies from people to people, even in an identical environment. To minimize the consumption of energy of building, cost of consumed energy and to provide a comfortable house, thermal comfort analysis in indoor environments have attracted many researchers. Fanger’s Predicted Mean Vote (PMV) - Predicted Percentage of Dissatisfied (PPD) model is widely accepted theory for assessment of building indoor thermal conditions. In the present work, thermal comfort of an LIG house in Chhattisgarh region of India has been analyzed based on PMV-PPD method for months representing three different seasons in a year i.e. May, September and December representing summer, post monsoon and winter respectively. Cooling, heating and actual energy load of LIG house has been calculated and reported for the above mentioned months. From analysis it is concluded that inhabitants are comfortable only during the winter

A PMV-PPD model based study of thermal comfort in Low-Income Group house in Chhattisgarh

People tend to maintain symmetry between comfort and economy while choosing essential commodities needed in their life. Families buy a house which may offer comfort condition, but at minimum in term expenses of energy throughout a life. Thus, it is most important to erect a house to provide comfortable condition and moderate the lifetime expenditure by saving energy consumption. Sensation of thermal comfort varies from people to people, even in an identical environment. To minimize the consumption of energy of building, cost of consumed energy and to provide a comfortable house, thermal comfort analysis in indoor environments have attracted many researchers. Fanger’s Predicted Mean Vote (PMV) - Predicted Percentage of Dissatisfied (PPD) model is widely accepted theory for assessment of building indoor thermal conditions. In the present work, thermal comfort of an LIG house in Chhattisgarh region of India has been analyzed based on PMV-PPD method for months representing three different seasons in a year i.e. May, September and December representing summer, post monsoon and winter respectively. Cooling, heating and actual energy load of LIG house has been calculated and reported for the above mentioned months. From analysis it is concluded that inhabitants are comfortable only during the winter

Exact solution for the thermo-elastic deformation and stress states of FG rotating spherical body

In this paper, a generalized solution for 1-D steady-state mechanical and thermal deformation and stresses in rotating hollow functionally graded spherical body is presented. Spherical shells are treated under mechanical and thermal loads in the form of rotational body force with heat generation. Temperature distribution is assumed to vary along the radial direction due to variable heat generation. General uniform mechanical boundary condition at inner and outer surfaces along with prescribed temperatures at both the ends are assumed as boundary conditions. In the present study, material properties are taken as power function of radius with grading parameter ranging between −2 to 3. Governing differential equation with variable coefficient is developed and solved to find deformation and stresses. The obtained results are verified with benchmark results and are found to be in good agreement. Results show that deformation and stresses decrease with an increase in the value of grading parameter and are less as compared to the homogeneous body