Paper Title, Authors, Abstract (Issue 1, Volume 3, 2009)

Pages

Energy Efficient Lighting - A Way to Conserve Energy
Arvind Dhingra, Tejinder Singh

Abstract: Energy is the source that has been driving the mankind in this technological era. Usage of energy depicts the level of development of a nation. The energy resources of the world are under severe pressure to cope up with the growing need of energy. The technological changes and changes in the lifestyle have increased the demand for energy tremendously. With the resources become scarce and energy costs growing, it becomes imperative for everyone to save energy or to use the available energy judiciously. The need is to either find new sources of energy or to use the energy available carefully. Lighting forms a major chunk of load on our electrical power system. Energy efficiency in lighting involves building architecture, selection of proper luminaries and light sources. This paper presents the study of energy conservation measures adopted in a spinning unit. The payback period is also calculated.
 

A New Power Swing Detection Scheme for Distance Relay Operations
Ahmad Farid Bin Abidin, Azah Mohamed, Hussain Shareef

Abstract: This paper presents a new detection scheme based on the derivative of the line reactive power as seen by a relay to prevent distance relay mal-operation during power swings. This proposed scheme overcomes the shortcoming of conventional power swing detector (PSD) by removing the pre-defined R-X diagram. The conventional PSD has the difficulty in obtaining the timer setting at pre-defined R-X diagram due to varying cycle of power swings. To illustrate the effectiveness of the proposed detector, the simulation were conducted on the IEEE 39 bus test system using the PSS/E software. The results show the effectiveness of the proposed detection technique to distinguish between a fault, fault clearance and power swing in order to activate the correct relay trip signals during power swings.
 

    Paper Title, Authors, Abstract (Issue 2, Volume 3, 2009)

Pages

Progress on the Problems of the Study in the Performance of a Solar Module under Conditions of Random Changes of Radiation
Liliana Cortez, J. Italo Cortez, Alejandro Adorno, Ernest Cortez, Mariano Larios

Abstract: The challenge of studying the performance of a solar array capable of abrupt changes in the radiation has a significant importance therefore the present work is based on the simulation of the interconnection of 36 solar cells in a photovoltaic solar module (MS), of the Solar Shell brand, model Shell Power Max 85-P, by means of a mathematical simulator MATLAB, which offers swiftness and easiness of use. Relating the percentage of shade in given conditions of radiation to the point of maximum transference of power is intended, in order to be able to analyze the effects of random changes in solar radiation, on the production of energy, in outdoor conditions. The simulator provides the parameters of an open circuit tension (Voc)), the short circuit current (Isc), the maximum power (Pmax), and the characteristic curves of the solar module, depending on the shade effect that can hover on it, enabling the random study of changes of solar energy, in energy production. The experimental segment for attestation, as well as some of the trials carried out in different conditions of solar radiation are shown.
 

Investigation of Realizing SDI with High Swirl Charge in a Motorcycle Engine
Yuh-Yih Wu, Hsien-Chi Tsai, Manh-Cuong Nguyen

Abstract: The targeted developments for future vehicles are how to reduce fuel consumption, pollutant emission while maintaining high level of engine performance. To deal with those issues, fuel system has been taken great concerns by scientists for a long period of time. As we know, Port Fuel Injection system (PFI) and Gasoline Direct Injection system (GDI) are popular techniques which are being used on commercial vehicles. This paper presents the possible improvement of engine performance by applying effect of swirl motion on lean-limit of semi-direct injection SI engine. The fuel goes into cylinder directly through intake valve near the middle intake stroke to make richer mixture around the spark plug, which is called semi-direct injection (SDI). Thus, this system includes high swirl charge, injection during intake valve opening, and air-assisted fuel injection. The modifications of intake port by using baffle plate and the other by closing one intake valve for the 125 cc, 4-valve, port-fuel-injection (PFI) engine to increase swirl ratio of in-cylinder air motions which helped to form rich mixture around spark plug, and lean mixture at other location which is so-called stratified charge. The CFD software was use to investigate the in-cylinder air motion. After that, the combustion characteristics of swirl charge were investigated. The SDI engine then was tested under lean conditions at 4500 rpm and 5300 rpm. Experimental results indicated that lean-limit was extended to maximum air-fuel ratio 25.26 (excess air ratio = 1.73) at swirl ratio 3.5 while brake specific fuel consumption and coefficient of cycle variation were very low. Finally, the ECE-40 driving cycle simulation was employed for lean burn SDI engine as well as the original PFI engine. Results show that by using SDI mode at low engine load operation of ECE-40 driving cycle, the fuel consumption, CO emission, and NOx emission were improved by 4%, 31.1%, and 5.9%, respectively. However, the HC emission was increased by 25%.
 

    Paper Title, Authors, Abstract (Issue 3, Volume 3, 2009)

Pages

Falling Film Heat Exchange and Backsplash on Horizontal Tube Bundles
Jiri Pospisil, Libor Chroboczek, Zdenek Fortelny, Pavel Charvat

Abstract: Tube bundles represent a very common type of heat exchanger that is used in many technical applications. The problem of heat and mass transfer in tube bundles attracts a lot of attention in connection with falling films in absorption processes employed in absorption cooling and refrigeration cycles. The paper presents results of parametrical studies focused on expression of horizontal tube spacing and falling liquid flow rate influence on falling film formation and heat transfer in atmospheric pressure. Due to the complexity of the problem the research was done experimentally on an experimental set-up with a bundle of horizontal replaceable tubes.
 

Optimization of Heat Carrier Distribution System in Thermal Power Stations
Ioan Sarbu, Doru Pelivan

Abstract: The present paper is a summary developed from the author’s studies, conducted over a period of many years and throughout the design, implementation, commissioning and servi-cing hot water boiler rooms, with temperature not exceeding 115 ?C. This paper relates to study the advantages and disadvantages of the principal, systems and modes of distribution of heat carrier, desig-ned according to the most used thermo hydraulic schemes of hot water boiler rooms with power over 100 kW. To eliminate these disadvantages, the authors propose a new distribution system apparently similar to those existing, but actually different, by its advantages. The main component of the proposed system is a "different" flow/return manifold of the heating carrier, called “monoblock flow/return manifold with separating diaphragm”.
 

    Paper Title, Authors, Abstract (Issue 4, Volume 3, 2009)

Pages

Numerical Analysis of the Laminar Forced Heat Convection between Two Coaxial Cylinders
Ioan Sarbu, Anton Iosif

Abstract: This paper presents a study of the dual reciprocity boundary element method (DRBEM) for the laminar heat convection problem between two coaxial cylinders with constant heat flux boundary condition. DRBEM is one of the most successful technique used to transform the domain integrals arising from the non-homogeneous term of the Poisson equation into equivalent boundary only integrals. This recently developed and highly efficient nume-rical method is tested for the solution accuracy of the fluid flow and heat transfer study between two coaxial cylinders. Since their exact solutions are available, DRBEM solutions are verified with different number of boundary element discretizations and internal points. The results obtained in this study are discussed with the relative error percentage of velocity and temperature solutions, and potential applicability of the method for the more complicated heat convection problems with arbitrary duct geometries.
 

Design of Optimal Water Distribution Systems
Ioan Sarbu

Abstract: The paper approaches the optimization of water distribution networks supplied from one or more node sources, according to demand variation. Traditionally, in pipe optimization, the objective function is always focused on the cost criteria of network components. In this study an improved linear model is developed, which has the advantage of using not only cost criteria, but also energy consumption, consumption of scarce resources, operating expenses etc. The paper treats looped networks wich have concentrated outflows or uniform outflow along the length of each pipe. An improved model is developed for optimal desing of new or partially extended water distribution networks, which operate either by means of gravity or a pump system.The model is based on the method of linear programming and allows the determination of an optimal distribution of commercial diameters for each pipe in the network and the length of the pipes which correspond to these diameters. Also, it is possible to take into account the various functional situations characteristic found during operation. This paper compares linear optimization model to the some others, such as the classic model of average economical velocities and Moshnin optimization model. This shows the good performance of the new model. For different analyzed networks, the saving of electrical energy, due to diminishing pressure losses and operation costs when applying the developed model, represents about 10…35%.`