Performance Evaluation of Modified Low-Temperature Cascade (MLTC) Type Refrigeration System

Siddiqui Mohd Waseem,Das Nishith Kumar,Sahoo R. K. 대한설비공학회 2021 International Journal Of Air-Conditioning and Refr Vol.29 No.3

An experimental investigation was carried out to study the performance evaluation of Modified Low-Temperature Cascade (MLTC) system, based on two-stage cascade type refrigeration system using the combination of R404A/R23 refrigerants. This system was developed using chilled water (CHW) in the condenser of high-temperature circuit (HTC) and pre-cooler (PC) in the low-temperature circuit (LTC). Isentropic compression efficiency is computed in this work and used here as an important parameter. Performance of MLTC system was compared with or without the introduction of PC into LTC. System’s coefficient of performance (COP) has also been compared with using CHW, cooling tower water (CTW), normal water (NW) into the HTC condenser. It has also been shown that COPs of the system are significantly affected by slight variation in the LTC and HTC evaporating temperatures. Presented parameters and comparisons are likely to help in developing a low-temperature (LT) refrigeration system with higher efficiency for industrial and other applications.

Substrate bias effects during diamond like carbon film deposition by microwave ECR plasma CVD

R.M. Dey,S.B. Singh,A. Biswas,R.B. Tokas,N. Chand,S. Venkateshwaran,D. Bhattacharya,N.K. Sahoo,S.W. Gosavi,S.K. Kulkarni,D.S. Patil 한국물리학회 2008 Current Applied Physics Vol.8 No.1

Diamond like carbon (DLC) coatings were deposited on silicon(11) substrates by microwave electron cyclotron resonance (ECR)plasma CVD process using a plasma of Ar and CH4 gases under the inuence of DC self bias generated on the substrates by applicationof RF (13.56 MHz) power. DLC coatings were deposited under the varying inuence of DC bias (. 60 V to. 150 V) on the Si substrates.atomic force microscopy (AFM), Hardness and elastic modulus determination technique, Raman spectroscopy, scanning electronmicroscopy (SEM) and contact angle measurement. The results indicate that the lm grown at. 100 V bias has optimised propertieslike high sp3/sp2 ratio of carbon bonding, high refractive index (2.262.17) over wide spectral range 4001200 nm, low roughness of0.8 nm, high contact angle (80.) compared to the lms deposited at other bias voltages (. 60 V and . with each other and nd august explanation under the subplantation model for DLC growth.

A Multizone Adaptive Parallel Scheme for Solidification in a Rectangular Cavity

R. K. Sahoo,V.Prasad,H. Zhang,W. K. Chui,F. Tangerman,J. Glimm 대한기계학회 1998 Heat transter conference Vol.7 No.1

Parametric Resonance Characteristics of Laminated Composite Curved Shell Panels in a Hygrothermal Environment

S.K Sahu,M.K.Rath,P.K Datta,R. Sahoo 한국항공우주학회 2012 International Journal of Aeronautical and Space Sc Vol.13 No.3

The present study deals with the parametric resonance behaviour of laminated composite curved shell panels in a hygrothermal environment using Bolotin’s approach. A simple laminated model is developed using first order shear deformation theory (FSDT) for the vibration and dynamic stability analysis of laminated composite shells subjected to hygrothermal conditions. A computer program based on the finite element method (FEM) in a MATLAB environment is developed to perform all necessary computations. Quantitative results are presented to show the effects of curvature, ply-orientations, degree of orthotropy and geometry of laminates on the parametric instability of composite curved shell panels for different temperature and moisture concentrations. The excitation frequencies of laminated composite panels decrease with the increase of temperature and moisture due to reduction of stiffness for all laminates.

Synchronization and Operation of Parallel Inverters using Droop Control

L. K. Sahoo,N. D. Thakur,K. Rai,P Sensarma,R. D. Jha,P. Mohanty,A Sharma 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5

To obtain a continuous power supply Distributed Generation (DG) with a Decentralized Power System (DPS), i.e. replacing a single UPS unit with multiple, smaller units in parallel, is emerging as new paradigm. The technically challenging aspect of DPS is the synchronization of inverters and load sharing among the parallel connected inverters. In this paper, a control method is proposed and implemented for synchronization and parallel operation of inverters. Droop control method has been used for equal power sharing, and design of power control loop. The design issues for voltage control loop are analyzed with the discussion of relative stability of the system. A current control loop is designed and analyzed to provide synchronization between the inverters.

Design and Construction of Nitrogen Liquefier

B. K, Choudhury,R. K. Sahoo,S. K. Sarangi 국제문화기술진흥원 2015 International Journal of Advanced Culture Technolo Vol.3 No.2

The design and construction of nitrogen liquefier begins with the process design of the cycle. The simulation of the cycles has been done using the software Aspen HYSYS. The compressor unit is available in the laboratory. Two number of high effectiveness, vacuum brazed aluminum plate fin heat exchangers are designed and fabricated. Turboexpander is designed and all of its components are fabricated. A suitable modification has been done with a precession needle valve to operate as a long stem JT valve. For separating the liquid, a phase separator is designed and fabricated. All the components are assembled inside a double walled cold box with pipes as per the process need. The necessary pressure, temperatureand other measuring instruments, valves and safety devices are mounted on the liquefier. After successful running of the liquefier, for the mass flow rate of 296 kg/hr for gaseous nitrogen, it is expected to deliver 17.44 lit/hr of liquid nitrogen.

Parametric Resonance Characteristics of Laminated Composite Curved Shell Panels in a Hygrothermal Environment

Sahu, S.K.,Rath, M.K.,Datta, P.K.,Sahoo, R. The Korean Society for Aeronautical and Space Scie 2012 International Journal of Aeronautical and Space Sc Vol.13 No.3

The present study deals with the parametric resonance behaviour of laminated composite curved shell panels in a hygrothermal environment using Bolotin's approach. A simple laminated model is developed using first order shear deformation theory (FSDT) for the vibration and dynamic stability analysis of laminated composite shells subjected to hygrothermal conditions. A computer program based on the finite element method (FEM) in a MATLAB environment is developed to perform all necessary computations. Quantitative results are presented to show the effects of curvature, ply-orientations, degree of orthotropy and geometry of laminates on the parametric instability of composite curved shell panels for different temperature and moisture concentrations. The excitation frequencies of laminated composite panels decrease with the increase of temperature and moisture due to reduction of stiffness for all laminates.

Carbon nanoflake growth from carbon nanotubes by hot filament chemical vapor deposition

Sahoo, S.C.,Mohapatra, D.R.,Lee, H.J.,Jejurikar, S.M.,Kim, I.,Lee, S.C.,Park, J.K.,Baik, Y.J.,Lee, W.S. Pergamon Press ; Elsevier Science Ltd 2014 Carbon Vol.67 No.-

We report the growth of carbon nanoflakes (CNFs) on Si substrate by the hot filament chemical vapor deposition without the substrate bias or the catalyst. CNFs were grown using the single wall carbon nanotubes and the multiwall carbon nanotubes as the nucleation center, in the Ar-rich CH<SUB>4</SUB>-H<SUB>2</SUB>-Ar precursor gas mixture with 1% CH<SUB>4</SUB>, at the chamber pressure and the substrate temperature of 7.5Torr and 840<SUP>o</SUP>C, respectively. In the H<SUB>2</SUB>-rich condition, CNF synthesis failed due to severe etch-removal of carbon nanotubes (CNTs) while it was successful at the optimized Ar-rich condition. Other forms of carbon such as nano-diamond or mesoporous carbon failed to serve as the nucleation centers for the CNF growth. We proposed a mechanism of the CNF synthesis from the CNTs, which involved the initial unzipping of CNTs by atomic hydrogen and subsequent nucleation and growth of CNFs from the unzipped portion of the graphene layers.

A comparative morphological study of electron beam co-deposited binary optical thin films of HfO2:SiO₂ and ZrO₂:SiO₂

R.B. Tokas,N.K. Sahoo,S. Thakur,N.M. Kamble 한국물리학회 2008 Current Applied Physics Vol.8 No.5

A comparative morphology, grain structure and optical properties studies of reactive electron beam co-evaporated mixed thin films of hafnia–silica (HfO₂:SiO₂) and zirconia–silica (ZrO₂:SiO₂) systems have been carried out using atomic force microscopy and phase modulated ellipsometry. The addition of silica, especially with small fractions, has demonstrated altogether different types of evolutions in the microstructure and morphology in these binary thin film systems possibly forming new solid solution phases. Such morphological evolutions are probed through RMS roughness, power spectral density, height–height correlation and autocorrelation analyses of the topographic data acquired through atomic force microscopy. The present investigations indicated that with composition-control morphological quality improvement is more favourable in composite hafnia–silica over the zirconia–silica films. So for ultraviolet optical coating applications which demand low light scattering thin film microstructure, hafnia–silica binary composite system has a definite edge over the zirconia–silica counterpart. A comparative morphology, grain structure and optical properties studies of reactive electron beam co-evaporated mixed thin films of hafnia–silica (HfO₂:SiO₂) and zirconia–silica (ZrO₂:SiO₂) systems have been carried out using atomic force microscopy and phase modulated ellipsometry. The addition of silica, especially with small fractions, has demonstrated altogether different types of evolutions in the microstructure and morphology in these binary thin film systems possibly forming new solid solution phases. Such morphological evolutions are probed through RMS roughness, power spectral density, height–height correlation and autocorrelation analyses of the topographic data acquired through atomic force microscopy. The present investigations indicated that with composition-control morphological quality improvement is more favourable in composite hafnia–silica over the zirconia–silica films. So for ultraviolet optical coating applications which demand low light scattering thin film microstructure, hafnia–silica binary composite system has a definite edge over the zirconia–silica counterpart.

Growth Performance of Lambs Fed Diet Supplemented with Rice Bran Oil as Such or as Calcium Soap

Bhatt, R.S.,Karim, S.A.,Sahoo, A.,Shinde, A.K. Asian Australasian Association of Animal Productio 2013 Animal Bioscience Vol.26 No.6

Forty two Malpura lambs (21 d old) were divided into three groups of 14 each consisting of 8 females and 6 males. Lambs were allowed to suckle their respective dams twice daily up to weaning (13 wks) and offered free choice concentrate and roughage in a cafeteria system. The lambs in control group were fed conventional concentrate mixture, in RBO group concentrate mixture fortified with 4% industrial grade rice bran oil and in Ca-soap rice bran oil (as in RBO group) was supplemented in the form of calcium soap. The concentrate intake decreased($p{\leq}0.05$) in RBO group as a result total dry matter, crude protein and metabolizable energy intake decreased compared to control whereas Ca-soap prepared from the same rice bran oil stimulated the concentrate intake leading to higher total dry matter, crude protein and energy intakes. The digestibility of dry matter ($p{\leq}0.05$), organic matter ($p{\leq}0.05$) and crude protein ($p{\leq}0.05$) was higher in RBO group followed by Ca-soap and control whereas no effect was observed for ether extract digestibility. Higher cholesterol ($p{\leq}0.05$) content was recorded in serum of oil supplemented groups (RBO and Ca-soap) while no effect was recorded for other blood parameters. Rice bran oil as such adversely affected and reduced the body weight gain ($p{\leq}0.001$) of lambs in comparison to control whereas the Ca-soap of rice bran oil improved body weight gain and feed conversion efficiency in lambs. Fat supplementation decreased total volatile fatty acids ($p{\leq}0.05$) and individual volatile fatty acid concentration which increased at 4 h post feeding. Fat supplementation also reduced ($p{\leq}0.05$) total protozoa count. Ca-soap of rice bran oil improved pre slaughter weight ($p{\leq}0.05$) and hot carcass weight ($p{\leq}0.05$). It is concluded from the study that rice bran oil in the form of calcium soap at 40 g/kg of concentrate improved growth, feed conversion efficiency and carcass quality as compared to rice bran oil as such and control groups.