Investigation of Trapezoidal-Cut Twisted Tape Insert in a Double Pipe U-Tube Heat Exchanger using Al2O3/Water Nanofluid

AbstractAn attempt is made to enhance the rate of heat transfer in heat exchangers using Al2O3 nanofluid. In this work an experimental analysis on trapezoidal-cut twisted tape insert in a double pipe U-tube heat exchanger using Al2O3 water based nanofluid is presented. The heat transfer coefficients and the corresponding friction factors required for performance analysis are determined taking into account the typical operating conditions of the heat exchangers in turbulent flow regimes with particle volume concentration of 0.01% and 0.03% and twist ratios ranging between 5 and 20. Experimental data is generated at flow rates ranging from 0.0333kg/s to 0.2667kg/s. Experimental data is generated with water and nanofluid for Reynolds number in the range 3000<Re<30000, the Nusselt number of entire pipe for 0.03% concentrations of nanofluid with trapezoidal-cut twisted tape inserts of H/D = 5 is enhanced by 34.24% as compared to water. The friction factor of entire pipes for 0.03% concentration of nanofluid with trapezoidal-cut twisted tape inserts of H/D=5 is enhanced by 1.29 times as compared to water. The results of the investigation indicate an enhancement in the performance parameters of the heat exchanger namely heat transfer coefficient and friction factor with an increase in volume concentration of the nanoparticle

Hydrodynamic Performance and Acoustic Response of Ship Propeller

The aim of the paper is to predict the hydrodynamic performance and noise generated by the propeller at different advance ratio and the speed of the propeller. Three bladed, DTMB 4119 propeller model was created using the NACA66 modified line, a = 0.8 hydrofoil profile. ANSYS Workbench software is used for mesh generation and computational analysis. A large-eddy simulation turbulence model and Ffowcs Williams-Hawkings (FWH) acoustic model is used for all simulations. A moving reference frame is used to simulate the rotational effects of the propeller. The speed of the propeller is 792 rpm, the propeller being 0.2 m, and inlet velocity is varied to study the effect of the advance ratio. A transient analysis is carried out using a time step value of 0.0005 seconds and the total simulation time is 0.6 seconds. The hydrodynamic performance parameters are validated by comparing with the experimental data available in the literature. The sound pressure level (SPL) is plotted over the frequency range of 0 to 1000 Hz at different locations, speed, and an advance ratio of 0.5, 0.7, 0.833, and 0.9,1. The structural, acoustic and hydrodynamic behaviour of the propeller was predicted using a two-way fluid structure interaction at an advance ratio of 0.833. The major conclusions drawn from the analysis are that the sound pressure level values are increased at the propeller off-design conditions and varying with the receiver locations. The data generated from this study is useful for the designers to carry out further research in order to reduce the noise generated from the propeller

Evaluation of Contact Stresses in Bearings Made of Al – Beryl Metal Matrix Composites by Finite Element Method

AbstractIn the present investigation, interference fitted assemblies were analyzed using finite element method to evaluate contact stresses. The main objective of this research work is to develop metal matrix composite of commercially available pure aluminum reinforced with different weight percentage of Beryl to attain a most desirable property combination for bearings. A detailed analysis on the effect of bearing material on contact stresses was undertaken. The work covers the analysis based on Hertzian contact stresses. An appropriate finite element model was developed to analyze the pattern of contact stresses in the interference assemblies. Ansys workbench was used as a tool to construct the model and to perform analysis. The model was simulated by applying a pressure of 100MPa and at different speeds of the shaft. A comparative study on the effect of bearing materials such as bronze, Al-SiC and Al-Beryl MMCs on contact stresses were clearly demonstrated. It has been found that the contact stresses in the bearings made of Al-Beryl metal matrix composite was in the range of 4678.7 to 4680Pa at different speeds which was very much less when compared to the bronze and Al- SiC MMC. The results clearly demonstrated Al-Beryl can be used as one of the most suitable materials for fabricating bushes

Multi-Level Inverter with Facts Capability for Reliable Power Distributions Using Wind Energy as Source

The paper manages the multilevel converters control procedure for photovoltaic framework coordinated in dispersion matrices. The proposed control plan guarantees the infusion of the produced power in the conveyance network with quick element reaction, while giving an extra dynamic force sifting ability giving the required consonant and responsive streams to be considered. The control plan is accepted by method for reenactments with a course converter which interfaces to a dispersion network. Additionally, for DC join voltage control, it is required that balances out the voltage at the inverter data to protect a ceaseless stream of vitality trade between the matrix and the PV framework. Likewise, a LC channel is important to channel the yield current and voltage from the sounds and to shield the network from their ruinous impact. At long last, this paper presents nitty gritty demonstrating of the framework joined photovoltaic era framework parts, in Simulink/Mat lab programming. Recreation results displayed to approve the parts models and the picked control plans. The outline and correlation of multi-level inverter with D-STATCOM for wind vitality frameworks utilizing Modular Multi-level Converter (MMC). The point of the work is to outline diverse levels of inverter with FACTS gadgets to give utilities more learning about the appropriation frameworks, particularly toward the end focuses. Henceforth made the correlation between these levels of inverters where the yield of the framework does not change with the levels of inverter but rather the Total Harmonic Distortion (THD) of the framework will lessens as the level increments. This inverter is put between the wind turbine and the conveyance network where the dynamic and responsive force is direct which is required by the lattice. Recreations of the proposed inverter with 11 level and 17 level have been done in MATLAB/Simulink. The reenactment results accept the execution of the proposed control system

Diversity pattern elucidating choice of parents for hybridization in varieties of groundnut, Arachis hypogaea L.

Genetic divergence within and between the four varietal groups, Spanish bunch, Valencia, Virginia bunch and Virginia runner, of groundnut (Arachis hypogaea L.) was assessed by Mahalanobis's D2 statistic using a representative sample of 40 germplasm lines in each group. Estimates of divergence were based on 17 characters spanning the seedling, flowering, post-flowering and harvest stages. The diversity within bunch groups was high enough to form six different clusters out of the total sixteen. The method used was thus efficient in diagnosing within-group divergence. The clustering pattern of the varieties remained essentially the same when the experiment was repeated on a sub-sample of 48 germplasm lines in the next season. The results revealed that identified bunch x bunch crosses involving divergent parents could combine earliness with productivity, and should be used to complement the currently advocated bunch x runner crosses. Flowering time, weight of mature pods, shelling percentage and seedling attributes, like number of leaves and shoot-root dry weight ratio, were found to be important in assessing genetic variance

Managing contamination delay to improve Timing Speculation architectures

Timing Speculation (TS) is a widely known method for realizing better-than-worst-case systems. Aggressive clocking, realizable by TS, enable systems to operate beyond specified safe frequency limits to effectively exploit the data dependent circuit delay. However, the range of aggressive clocking for performance enhancement under TS is restricted by short paths. In this paper, we show that increasing the lengths of short paths of the circuit increases the effectiveness of TS, leading to performance improvement. Also, we propose an algorithm to efficiently add delay buffers to selected short paths while keeping down the area penalty. We present our algorithm results for ISCAS-85 suite and show that it is possible to increase the circuit contamination delay by up to 30% without affecting the propagation delay. We also explore the possibility of increasing short path delays further by relaxing the constraint on propagation delay and analyze the performance impact

Expectation of forward-backward rapidity correlations in p+pp+p collisions at the LHC energies

Forward-backward correlation strength ($b$) as a function of pesudorapidity intervals for experimental data from $p+\bar{p}$ non-singly diffractive collisions are compared to PYTHIA and PHOJET model calculations. The correlations are discussed as a function of rapidity window ($\Delta \eta$) symmetric about the central rapidity as well as rapidity window separated by a gap ($\eta_{gap}$) between forward and backward regions. While the correlations are observed to be independent of $\Delta \eta$, it is found to decrease with increase in $\eta_{gap}$. This reflects the role of short range correlations and justifies the use of $\eta_{gap}$ to obtain the accurate information about the physics of interest, the long range correlations. The experimental $b$ value shows a linear dependence on $\ln \sqrt{s}$ with the maximum value of unity being reached at $\sqrt{s}$ = 16 TeV, beyond the top LHC energy. However calculations from the PYTHIA and PHOJET models indicate a deviation from linear dependence on $\ln \sqrt{s}$ and saturation in the $b$ values being reached beyond $\sqrt{s}$ = 1.8 TeV. Such a saturation in correlation values could have interesting physical interpretations related to clan structures in particle production. Strong forward-backward correlations are associated with cluster production in the collisions. The average number of charged particles to which the clusters fragments, called the cluster size, are found to also increase linearly with $\ln \sqrt{s}$ for both data and the models studied. The rate of increase in cluster size vs. $\ln \sqrt{s}$ from models studied are larger compared to those from the data and higher for PHOJET compared to PYTHIA. Our study indicates that the forward-backward measurements will provide a clear distinguishing observable for the models studied at LHC energies.Comment: 15 pages, 14 Figures, accepted for publication in International Journal of Modern Physics

Methyl 2-(thio­phene-2-carboxamido)­benzoate

The title compound, C13H11NO3S, was synthesized from methyl anthranilate, triethyl­amine and 2-thio­phenoyl chloride in benzene. The mol­ecular conformation is stabilized by an intra­molecular N—H⋯O hydrogen bond. The dihedral angle between the rings is 2.74 (12)°. In the crystal, C—H⋯O inter­actions link neighbouring mol­ecules into a three-dimensional network