Rajnish K. Calay

Energy harvesting from suspension systems using regenerative force actuators

In this paper, harvesting vibration energy from suspension is investigated. Theoretical values for the harvested energy are calculated. Experimental evaluation of the energy is performed using vehicle road simulation facilities. An excitation signal in the frequency range of 0.5 Hz to 20 Hz is applied to the vehicle and the harvested power is calculated. Experimental results give a maximum harvested power of 984.4 W at the highest frequency, which is close to the theoretically computed value of 1,106 W, for each suspension. Application of regenerative force actuators (RFA) is explored for harvesting the vibration energy and controlling vibration. It is shown that the harvested power increases with the value of the actuator constant.

Modelling and analysis of a novel wind turbine structure

This study introduces a novel wind turbine structure for an urban environment. A computational modelling has been conducted to investigate the effect of the new structure on the flow behaviour of entrance wind through the structure and the feasibility of the new wind turbine working at different wind speeds in an urban area. The wind flow behaviour through a chamber of the wind turbine structure has resulted in an increase of 1.3 times of the wind velocity at the outlet of the wind turbine. This is equivalent to 2.5 times increase of wind energy. The wind tunnel tests were carried out to validate the simulation results. There is a good correlation between the experimental and computational results. It is evident that the presented computational method can predict and evaluate the performance of this new type of shroud structure in an urban environment.

On power and control systems of the multibody advanced airship for transport

The concept of the multibody advanced airship for transport (MAAT) is presented. The power, propulsion and control systems of the airship are discussed. The energy required for operation of this airship is supplied by a solar-fuel cell system. Solar panels and fuel cells provide the power associated with the airship motion and avionics, including the control and propulsion systems. Uncertainties in modelling of the airship and a method of dealing with such uncertainties are addressed in the framework of optimal uncertainty quantification. A complete model of this airship is presented by integrating the power, propulsion and control system. The model provides the base line for the design and analysis of the airship and investigation of its components, i.e., energy, control and propulsion systems.

CFD Simulation of Soil Flow Over Augers

The modelling of soil as an engineering material is confined, in the most part, to the investigation of how it behaves under loading and unloading. A key assumption made in existing models is that the soil is similar in behaviour to a solid and is generally elastic-perfectly plastic and has a linear stress strain relationship. The rapid displacement of soil, such as flow, has been studied far less. The aim of this paper is to study such behaviour and present the initial results of the flow around a rotating auger assuming the soil acts as a fluid. These initial simulations rely on the governing equations of fluid flow assuming Newtonian viscosity. Although evidence points to soil not having constant coefficient of viscosity, this study and a further study by Tardos [1] shows that for loose soils with a low angle of internal friction, such as liquefied sand, the Newtonian viscosity is an acceptable assumption. The patterns of soil movement around the auger are shown over two different drilling tools. Visual and numerical results of soil movement are presented.© 2002 ASME

Experimental Investigation of a Novel Design of Proton Exchange Membrane Fuel Cell Stack

A design study of a novel proton exchange membrane fuel cell (PEMFC) is presented in this article. The PEMFC is particularly suited to the automotive and small-scale stationary industries; however, at this stage it fails to be a viable commercial alternative to the internal combustion engine. This is mainly due to large material and manufacturing costs associated with components used in the fuel cell. A new design approach that removes the bipolar plate from the PEMFC stack is investigated. A single PEMFC, which features the design changes that can be integrated in the main stack, has been designed, manufactured, assembled, and tested to obtain performance characteristics for a range of operating conditions. Two different flow configurations for the reactants, that is, dead-end gas flow and through-mode flow, were tested. The new design achieved performance comparable to that with conventional designs reported in literature. The experimental results confirmed that bipolar plate can be removed and it is possible to bring down the costs and weight of the stack drastically. It is envisaged that the new design will allow the PEMFC to potentially inject into the current market.

Challenges Facing Hydrogen Fuel Cell Technology to Replace Combustion Engines

In this paper; technological challenges and commercialization barriers for Proton Exchange Membrane (PEM) fuel cell are presented. Initially, the criteria that must be met by the energy source of the future is presented from the point of view of the authors. Sustainability, high energy content and combustion independence are recognized as the main decisive factor of future fuels, which are all met by hydrogen, consequently the application of fuel cells as combustion free direct energy converters of the future. Fuel cell technology as an alternative to heat engines is discussed in the context of the current status of fuel cells in various applications. Finally, the challenges facing fuel cell technology to replace heat engines from the commercial and research points of view are presented and discussed supported by current trends in the industry. It is concluded that there have been several advancements and breakthrough in materials, manufacturing and fabricating techniques of fuel cells since the eighties, many of these challenges which are associated with cost and durability still exist when compared with the already matured technology of internal combustion engines. Any effort to achieve these goals would be a significant contribution to the technology of the fuel cell.

Renewable energy technologies and practices: Prospective for building integration in cold climates (Kazakhstan)

Renewable energy generation and its integration with the built environment are becoming one of the main concerns of the global construction industry. It is believed that this solution is essential in addressing the growing challenges of global energy scarcity and the consequences of greenhouse gas effect. Buildings are the major end-users of energy worldwide; therefore, any measures implemented by the industry to generate and apply renewable energy should lead to the target cuts in CO2 emissions. Kazakhstan, as a member of the international community, is not an exception. Rapid economic growth and associated booms in the construction industry have caused a sharp increase in energy usage, simultaneously causing a significant negative impact on the environment. The government is seeking ways of learning and transferring international knowledge and experience in this field to cope with the above mentioned challenges. Thus, this work outlines and discusses modern building design strategies and measures and the use of renewable technologies, with specific focus on countries with cold climates. It also attempts to develop up-to-date expertise on renewable energy integration into contemporary buildings. Among others, these include the use of alternative and low impact, renewable energy forms such as solar, wind, geothermal, and biomass energy. A case study was conducted in order to test the hypothesis that renewable energy technologies, solar photovoltaic (PV) systems in particular, can be a sensible and practical solution to reduce the building sectors energy use from the grid and subsequently diminish carbon dioxide emissions. Thus, the paper has attempted to estimate energy usage of a building model with and without installation of a PV system and makes a basic economic calculation based on approximate market prices for installation and maintenance. This has allowed an estimation of estimating the approximate payback periods and make conclusions on the rational of integration of this solar energy technology in Kazakhstan (for cold, as well as, warm temperatures). Findings have shown that with present underdeveloped PV market and prohibitively expensive initial cost, the payback period is far more than it is in developed countries. A number of recommendations have been made to the government of Kazakhstan to make this technology more applicable and financially viable.

Experimental Investigation of Emissions from Biodiesel

Biodiesel from waste cooking oil offers sustainable alternative to diesel. This paper presents an experimental investigation of combustion of biodiesel derived from waste cooking oil to study the characteristics of biodiesel emissions compared to diesel. The combustion of neat biodiesel and biodiesel blended in different ratios with diesel was investigated using continuous combustion rig. The temperature of combustion gases, emissions of un-burnt HC and NO for different airflow rates were evaluated. Differences in the chemical composition between biodiesel and diesel result in different mechanisms of NO and HC formation. The results provide insight into combustion and emission from biodiesel. It was observed that the combustion gas temperature (CGT), adiabatic flame temperature, unburned hydrocarbon (HC) and carbon monoxide (CO) decrease, while nitrogen oxides (NOx) increases when the proportion of biodiesel is increased in the blend. Combustion of biodiesel blends for 2% excess O2 shows the best compromise between the reduction in unburned HC and the lowest increase in NOx. It can be concluded that biodiesel made from waste cooking oil has potential to use as alternative to diesel fuel in internal combustion engine and has significant environmental benefits compare to diesel.

A Model to Predict Stratification in Two Phase Flow in Horizontal Pipes

Stratified flow is encountered in many situations. The flow of hydrocarbons transported in horizontal pipes often gets stratified. The prediction of pressure drop and liquid hold-up is essential for reservoir and pipe management and optimizing the cost of transportation of constituents. The present paper presents a simple mathematical model to predict the pressure drop, water and oil hold up and stratified layer. A good agreement with the experimental data was found. The model will be further developed and incorporated within a numerical model in order to investigate the flow field characteristics and establish correlations for a wide range of parameters.Copyright

CFD Modelling of Multiphase Flows: An Overview

The Computational Fluid Dynamics (CFD) is now increasingly being used for modeling industrial flows, i.e. flows which are multiphase and turbulent. Numerical modeling of flows where momentum, heat and mass transfer occurs at the interface presents various difficulties due to the wide range of mechanisms and flow scenarios present. This paper attempts to provide a summary of available mathematical models and techniques for two-phase flows. Some comments are also made on the models available in the commercially available codes.Copyright