Research on the design of hydrogen supply system of 70 MPa hydrogen storage cylinder for vehicles

A hydrogen supply system of 70 MPa hydrogen storage cylinder on vehicles is designed, in which a compressor is proposed to use the new type of ion compressor. The system is simulated statically by Aspen Plus. Meanwhile, during the process of hydrogen charged from the third-stage high-pressure hydrogen storage tank to the hydrogen storage cylinder on vehicles, the dynamic variety of the third-stage high-pressure hydrogen storage tank is simulated dynamically by Aspen HYSYS Through the simulation, obtaining the results that there are difference between theoretical calculation and simulation for the volume of third-stage high-pressure hydrogen storage tank and the average volume flow of hydrogen in a third-stage high-pressure hydrogen storage tank varies with its pressure and volume. By comparing the results of Aspen Plus simulation and Aspen HYSYS simulation, there are some differences. The designed system can be applied to hydrogen stations and any operating conditions involving the supply hydrogen.     

Stress concentration in cone–cylinder intersection

The finite element method and shell theory were employed to investigate cone–cylinder shell intersections. The developed special-purpose computer program Sais (stress analysis in intersecting shells) was used for elastic stress analysis of branch connections. A comparison of calculated results with experimental data is presented. A parametric study of non-radial models of the cone–cylinder shell intersection subjected to internal pressure loading was performed. The intersections of thin and middle thickness shells were analysed. The results are presented in graphical form. Non-dimensional geometric and angular parameters are considered to analyse the effects of changing these parameters on stress ratios in the shell intersection.     

Laminar film condensation of downward flowing vapour on a horizontal elliptic cylinder — A numerical solution

An explicit numerical method for two dimensional film condensation problems is proposed and applied to evaluate the overall heat transfer on elliptic cylinders. The effect of liquid film inertia, enthalpy convection, pressure gradient and surface tension have been taken into account. The agreement between the results of the present calculations with existing theories is satisfactory.     

Numerical simulation of heat transfer and fluid flow past a rotating isothermal cylinder – A LBM approach

In this paper, a viscous fluid flowing past a rotating isothermal cylinder with heat transfer is studied and simulated numerically by the lattice Boltzmann method (LBM). A numerical strategy for dealing with curved and moving boundaries of second-order accuracy for both velocity and temperature fields is proposed and presented. The numerical strategy and method are validated by comparing the present numerical results of flow without heat transfer with those of available previous theoretical, experimental and numerical studies, showing good agreements. On this basis, the convective heat transfer performance in such rotational boundary environments is further studied and validated; the numerical results are reported in the first time. The effects of the peripheral-to-translating-speed ratio, Reynolds number and Prandtl number on flow and heat transfer are discussed in details.     

Effect of hydrogen-diesel fuel co-combustion on exhaust emissions with verification using an in–cylinder gas sampling technique

The paper presents an experimental investigation of hydrogen-diesel fuel co-combustion carried out on a naturally aspirated, direct injection diesel engine. The engine was supplied with a range of hydrogen-diesel fuel mixture proportions to study the effect of hydrogen addition (aspirated with the intake air) on combustion and exhaust emissions. The tests were performed at fixed diesel injection periods, with hydrogen added to vary the engine load between 0 and 6 bar IMEP. In addition, a novel in–cylinder gas sampling technique was employed to measure species concentrations in the engine cylinder at two in–cylinder locations and at various instants during the combustion process.     

Natural convection flow of Cu–Water nanofluid in horizontal cylindrical annuli with inner triangular cylinder using lattice Boltzmann method

In this paper the lattice Boltzmann method is used to investigate the effect of nanoparticles on natural convection heat transfer in two-dimensional horizontal annulus. The study consists of an annular-shape enclosure, which is created between a heated triangular inner cylinder and a circular outer cylinder. The inner and outer surface temperatures were set as hot (T_h) and cold temperatures (T_c), respectively and assumed to be isotherms. The effect of nanoparticle volume fraction to the enhancement of heat transfer was examined at different Rayleigh numbers. Furthermore, the effect of vertical, horizontal, and diagonal eccentricities at various locations is examined at Ra = 10⁴. The result is presented in the form of streamlines, isotherms, and local and average Nusselt number. Results show that the Nusselt number and the maximum stream functions increase by augmentation of solid volume fraction. Average Nusselt number increases when the inner cylinder moves downward, but it decreases, when the location of inner cylinder changes horizontally.     

Investigation on the effect of injection system parameters on performance and emission characteristics of a twin cylinder compression ignition direct injection engine fuelled with pongamia biodiesel–diesel blend using response surface methodology

This study is aimed at investigating the effect of injection system parameters such as injection pressure, injection timing and nozzle tip protrusion on the performance and emission characteristics of a twin cylinder water cooled naturally aspirated CIDI engine. Biodiesel, derived from pongamia seeds through transesterification process, blended with diesel was used as fuel in this work. The experiments were designed using a statistical tool known as Design of Experiments (DoE) based on response surface methodology (RSM). The resultant models of the response surface methodology were helpful to predict the response parameters such as Brake Specific Energy Consumption (BSEC), Brake Thermal Efficiency (BTE), Carbon monoxide (CO), Hydrocarbon (HC), smoke opacity and Nitrogen Oxides (NO_x) and further to identify the significant interactions between the input factors on the responses. The results depicted that the BSEC, CO, HC and smoke opacity were lesser, and BTE and NO_x were higher at 2.5 mm nozzle tip protrusion, 225 bar of injection pressure and at 30° BTDC of injection timing. Optimization of injection system parameters was performed using the desirability approach of the response surface methodology for better performance and lower NO_x emission. An injection pressure of 225 bar, injection timing of 21° BTDC and 2.5 mm nozzle tip protrusion were found to be optimal values for the pongamia biodiesel blended diesel fuel operation in the test engine of 7.5 kW at 1500 rpm.     

Hybrid nanofluid flow over a stretched cylinder with the impact of homogeneous–heterogeneous reactions and Cattaneo–Christov heat flux: Series solution and numerical simulation

The Catteno–Christov heat flux plays a dynamic role in flow of heat enhancement in various manufacturing, industrial, and engineering applications. This present work focuses on the influence of Catteno–Christov heat flux model on Darcy–Forchheimer flow of a hybrid nanofluid placed in a porous medium. The formulation of the mathematical model is done by considering a fluid with two different nanoparticles Al₂O₃ and Cu dispersed in the water as the base fluid. The set of partial differntial equations is reduced by using similarity variables and boundary conditions to obtain ordinary differntial equations. The coupled nonlinear governing differential equations are solved using Runge–Kutta fourth–fifth order (RKF-45). The impact of numerous dimensionless parameters on the velocity, thermal, and concentration profiles are plotted and studied. Furthermore, the coefficient of skin friction for the relevant parameters are analysed through graphs. Result reveals that, increase in the porosity parameter declines the velocity gradient and shoots up the thermal and concentration gradients. Inclination in magnetic parameter declines velocity and concentration profiles due to the Lorentz force. Enhancement in the thermal relaxation parameter declines the thermal profile. Inclination in homogeneous-heterogeneous reaction parameters declines the mass transfer rate. Also, the well-known differential transform method is used for the validity of RKF-45 method and an impressive agreement is noticed between the results of RKF-45 and DTM.     

Non-linear,unsteady free convection in a vertical cylinder submitted to a horizontal thermal gradient: measurements in water between 6 and 21°C and a theoretical model of convection

The non-linear, unsteady behaviour of water contained in a vertical cylinder of yellow brass when submitted to a horizontal initial thermal gradient is investigated by following the temperature decay in the centre of a cylinder. Experimental results are interpreted by means of a theoretical model which allows the deduction of equations for temperature, velocity, pressure and density in the nucleus. The new equations are compared with those of conduction to provide an evaluation of the convective contribution to heat transfer. Our data indicate that when a characteristic dimensionless group which has the form of a Rayleigh number reaches a critical value of 1600 ± 50, the heat transfer may be described by a pure conduction equation.     

Entropy generation in a hollow cylinder with temperature dependent thermal conductivity and internal heat generation with convective–radiative surface cooling

This article investigates entropy generation in an asymmetrically cooled hollow cylinder with temperature dependent thermal conductivity and internal heat generation. The inside surface of the cylinder is cooled by convection on its inside surface while the outside surface experiences simultaneous convective–radiative cooling. The thermal conductivity of the cylinder as well as the internal heat generation within the cylinder are linear functions of temperature, introducing two nonlinearities in the one-dimensional steady state heat conduction equation. A third nonlinearity arises due to radiative heat loss from the outside surface of the cylinder. The nonlinear system is solved analytically using the differential transformation method (DTM) to obtain the temperature distribution which is then used to compute local and total entropy generation rates in the cylinder. The accuracy of DTM is verified by comparing its predictions with the analytical solution for the case of constant thermal conductivity and constant internal heat generation. The local and total entropy generations depend on six dimensionless parameters: heat generation parameter Q, thermal conductivity parameter β, conduction–convection parameters Nc₁ and Nc₂, conduction–radiation parameter Nr, convection sink temperature δ and radiation sink temperature η.     

Theoretical and technological aspects of flow batteries：Measurement of state of charge

电池实际可放出的瓦时容量与实际可放出的最大瓦时容量的比值定义为荷电状态,准确测定荷电状态对储能应用十分重要。本文从理论和应用角度,讨论全钒液流电池荷电状态的理论概念、工程定义和主要影响因素;提出2种确定最大瓦时容量的方法,其中实测法准确度更高,包含钒离子跨膜迁移、水分子扩散、负极电解液析氢和被氧化的信息,用于表征储能系统的荷电状态具有实际价值;阐述最大瓦时容量、电化学瓦时容量和理论瓦时容量的区别与联系。所提出的荷电状态确定方法,能够用于全钒液流电池SOC的估计。     

An Experimental Study of Three-Dimensional Characteristics of Turbulent Wakes of Axial Compressor Rotors

This paper presents an experimental investigation of the characteristics of three-dimensional turbulent wakes of an isolated axial compressor rotor and a single-stage axial compressor rotor. The wakes were measured from hub to tip using a single-slant hot-wire and a four-hole conical high frequency pressure probe. The experiments were made at both design and near stall conditions. Variations of mean velocities, total pressure, static pressure and turbulence stresses in the wakes are shown and interpreted. The experimental data from the isolated compressor rotor wake are compared with that from the single-stage compressor rotor.     

Challenges of Tomorrowm——Fire Hazards of Systems Using Renewable Sources of Energy

Dramatic climate change, caused by over consumption of coal, oil and other traditional energy sources, as well as exhaustion of their reserves, imposed technological need to look for their substitution with new, renewable energy sources. The exploitation of these new forms of energy, solar, wind, earth and bio-fuels, initiated the development and application of new technologies, so far unused in practice. Rapid development and wide application of installations for use of renewable energy in many households and companies opened a whole new risk and danger in the fire protection field. With the purpose of introducing this problem to engineers in the area of fire protection, health and safety at work, this paper systematically presents various types of facilities for exploitation of renewable energy sources as well as potential dangers, risks and issues related to their safe operation.     

Evaluation of criteria for design of current collectors of the lead–acid battery

The effect of the main structural parameters of the current collectors on efficiency of operation of the positive electrode of the lead–acid battery was investigated.     

Simulation of the behaviour of a set of Cu2SCdS unit photocells

With the help of a general simulation program (the Spice II program from the University of California, Berkeley), adapted to photocell modelling, we studied the behaviour of a large solar photocell consisting of smaller Cu₂SCdS unit solar cells in parallel. In particular we examined a theoretical set of photocells identical with the best cell made in the laboratory, a set of 30 real photocells characterized individually and the effect of introducing low efficiency cells.We indicate the role of each parameter characterizing the photocells in order to improve the behaviour of photovoltaic panels of larger dimensions.     

Energy consumption in iodine section of I–S: Effect of operating parameters of electro-electrodialysis on overall efficiency of cycle

Reducing heat demand for increasing concentration of HI in the HI_x solution of the iodine circuit of the Iodine–Sulphur cycle is considered the most effective way of increasing efficiency of the cycle. Electro-electrodialysis has emerged as an energy efficient way of increasing the HI_x concentration above azeotropic value. Simulation of the iodine circuit consisting of an EED, a flash and a decomposer was carried out in Aspen Plus™ simulation platform to study the effect of EED current density and outlet HI concentration on the efficiency of the cycle. Efficiency reduced strongly with increase in current density. For EED current density of 5 A/dm², maximum efficiency was ∼35.9% and the optimal range of EED catholyte's exit HI concentration, iodine-free, mole fraction was 0.19–0.21. Simulation results showed that reducing EED resistance was most effective, among all EED parameters, in increasing the cycle's thermal efficiency and if the EED resistance is completely eliminated the thermal efficiency value would increase to 39.4%.     

Characteristics of Compression Wave Caused by Reflection of Expansion Wave at Open End of Tube

When an expansion wave propagated along a constant area straight tube reaches at the open end, the negative impulsive wave and the compression wave are formed by the emission and reflection of expansion wave. The negative impulsive wave is emitted toward the surrounding area and causes an impulsive noise like the sonic boom. The compression wave propagates in the tube toward the upstream and may cause the impulsive noise at the surrounding area of tube portal. With the advance of industrial engineering, it seems that the discharging of the expansion wave will become important problems. In this study, the experimental and numerical investigations are carried out using the shock tube and the TVD numerical method. The formation process of compression wave near the open end, the relationship with the compression wave and the expansion wave and the characteristics of compression wave are discussed.     

Comparison of Performances of Turbines for Wave Energy Conversion

The Wells turbine for a wave power generator is a self-rectifying air turbine that is available for an energy conversion in an oscillating water-air column without any rectifying valve. The objective of this paper is to compare the performances of the Wells turbines in which the profile of blade are NACA0020, NACA0015, CA9 and HSIM15-262123-1576 in the small-scale model testing. The running characteristics in the steady flow, the start and running characteristics in the sinusoidal flow and the hysteretic characteristics in the sinusoidal flow were investigated for four kinds of turbine. As a conclusion, the turbine in which the profile of blade is NACA0020 has the best performances among 4 turbines for the running and starting characteristics in the small-scale model testing.     

The Study of the Damage Laws of Pool Fires

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