Paper Title, Authors, Abstract (Issue 1, Volume 1, 2007)

Pages

Remotely Operated Vessel for Environmental Studies in Shallow Water Areas
Rafic Bachnak and Jack Esparza

Abstract: Data collection in shallow water areas presents several challenges to the scientist. In addition to being redundant and time consuming, this task when performed manually has a high probability of disturbing the test area. Obstacles that are encountered
in such environments include difficulty in covering large territories and the presence of inaccessible areas due to a variety of reasons, such as soft bottoms or contamination. There is also a high probability of disturbing the test area while placing the sensors. This
paper describes the development of a remotely-controlled, shallow draft vehicle designed as a supplemental tool for our studies of the South Texas Coastal waters. The system transmits environmental
 

A real-time monitoring and diagnostic procedure for electrical distribution networks
Francesco Muzi, Luigi Passacantando

Abstract: A monitoring and diagnostic approach based on the circuit theory is presented. The proposed procedure allows a continuous control of all network branch admittances, including conductances associated to insulation levels between phases and phase-to-ground. The detection of possible anomalies can be suitably used to activate proper protection or maintenance procedures. The monitoring process allows to prevent sudden, large-scale supply interruptions which might give rise to very serious problems in the operation of secondary networks. In addition, corrective maintenance of an electrical system can be usefully scheduled subdividing the network into different zones in order to achieve both considerable maintenance savings and remarkable quality improvements in distribution services. Finally, the possibility to promptly eliminate small anomalies can avoid more serious damages involving large network areas. An extensive simulation work was performed to test the proposed algorithm and results, mainly concerning the diagnosis of insulation between phases, are reported and discussed.
 

Power and Energy Characteristics of Continuous Waves / Pulsed CO2 Laser Application in CNG-DI Ignition
N. Mariun, N. Md. Saad, M. F. Abas, N. Khan and S. Abdullah

Abstract: This work was arranged to develop the scientific database and integrate the application of lasers in high voltage engineering. The design and experimental studies on continuous wave (CW) / repetitively pulsed CO2 laser was carried out in detail to determine the laser characteristics between various design parameters and the effect of varying one parameters on others. The thresholds and steady state input voltage and power across the laser tube are determined. The maximum and minimum output energy and power of the laser system are also presented as function of the pulse repetition rate and discharge current. The CO2 laser system was operated at 10.6 μm wavelengths range of infrared electromagnetic spectrum. This study is presented due to the wide applications of CO lasers in industry and for this project for compressed natural gases-direct injection (CNG-DI) ignition.
 

Economic Analysis of Geothermal Heat Source for Residential Area Project
S.Poberžnik, D. Goricanec, J. Krope

Abstract: The article discusses the economic analysis of heat source for residential area project. The energy source is geothermal energy. Every house has its own borehole heat exchanger (BHE) and heat pump in basement. In this system low temperature floor and wall heating was carried out. The economic analysis was performed as a pilot study for real system with all installation needed to run the system. The analysis has been done using the method of the net present value. In the research the coefficient of profitability and the period of time in which the investment is going to return itself were established. The system has been compared to the conventional system that uses fossil fuel (Liquidized naphtha gas- LNG) to heat the building and domestic hot water.
 

        Paper Title, Authors, Abstract (Issue 2, Volume 1, 2007)

Pages

Voltage Deviation of Wind Power Generation due to Wind Velocity Change
J. Arai, R. Yokoyama, K. Iba, Y. Zhou, Y. Nakanishi

Abstract: The present paper treats an induction machine as a wind power generator, and voltage deviation due to wind velocity change is simulated by a dynamic stability calculation program. The ac bus voltage connected to the wind generator depends strongly on the wind velocity variation. The wind velocity, which is used for the simulation, was measured. The present paper shows that one-second sampling data of the wind velocity is needed for evaluation of voltage deviation.
 

Characterization of the Radial Structures for the Operation of a Real Medium Voltage Distribution System
Horia Andrei, Gianfranco Chicco, Mircea Popa, and Marius Silaghi

Abstract: Distribution system reconfiguration is based on searching for effective radial network structures from the weakly meshed structure of the physical network. For large distribution systems, this search is particularly challenging, due to the extremely high number of possible radial structures. This paper illustrates a suitable technique based on the creation of a reduced weakly meshed network containing the basic information required to apply further numerical techniques for identifying the radial network structures. The network components, including branches, loads and the connections to the supply system, are taken into account to form a layered structure. This layered structure can be used as a reference for identifying the most suitable radial configuration according to a specified objective function, by resorting to deterministic or heuristic methods. An example of application to a large real distribution system is shown.
 

Laminar mixed convection in the entrance region of horizontal quarter circle ducts
Yousef M. F. El. Hasadi

Abstract: Laminar mixed convection in the entrance region for horizontal quarter circular ducts with the curved wall on top has been investigated. The governing momentum and energy equations were solved numerically using a marching technique with finite control volume approach following the SIMPLER algorithm. Results were obtained for the thermal boundary conditions of uniform heat input axially and with uniform wall temperature circumferentially (H1 boundary condition) with Pr=0.7 and a wide range of Grashof numbers. These results include velocity, temperature distributions, at different axial locations, covering all aspects of flow, axial distribution of local Nusselt numbers and local friction factor. It was found that Nusselt numbers were close to the forced convection values near the entrance region and then decreasd to a minimum as the distance from the entrance increases and then rises due to the effect of free convection before reaching constant value (fully developed). As Grashof number increases Nusselt number and friction factor increases in both developing and fully developed regions and the location of the onset of the secondary flow moves upstream.
 

        Paper Title, Authors, Abstract (Issue 3, Volume 1, 2007)

Pages

A Numerical Discretization Method for the Dynamic Simulation of a Double-Pipe Heat Exchanger
Stefano Bracco, Ilka Faccioli, and Michele Troilo

Abstract: The present paper deals with both the steady-state and dynamic simulation of a double-pipe heat exchanger, in parallel-flow or counterflow arrangement. In particular, the article describes the thermodynamic model that has been implemented in the Matlab/Simulink environment; the main hypotheses and physical parameters, which characterize the simulation model, are listed. The paper is focused on the discretization of the heat exchanger which has been divided into N cells, each modeled by means of the energy balance equation. It’s important to point out that the model considers the storage of thermal energy in the metal parts and the method of discretization, that has been adopted, gives just acceptable results dividing the heat exchanger in a small number of cells. The paper shows some results of the steady-state simulation of a counterflow heat exchanger, as a function of the number of cells, and the effects of some typical transient operating conditions are described.
 

Renewable Energy Sources in Combined Systems – On-line System for Measuring and Collecting Data
Petr Mastny, Antonin Matousek, and Jan Machacek

Abstract: Research on the Department of Electrical Power Engineering FEEC, Brno University of Technology is among other things focused on the utilization of alternative power sources. The present situation within the field of power engineering positively encourages the research development of alternative power sources. Great attention is paid to increasing the efficiency and effectivity of power system operation. The paper presents results of the research in the field of alternative power sources utilization. It mainly points the possibilities of increasing the efficiency of alternative power sources operation by its mutual cooperation. Aspects of the cooperation are evaluated mainly from the energy point of view but the economic parameters of these systems are pointed as well. The paper also presents results of long-term measuring on active solar system connected into one unit together with a heat pump- the system has been installed in the university laboratories. The parameters of the measuring system that has been installed in the laboratories of the Department of Power Engineering are described as well. The research proved that new approach to the cooperation of heat pump and solar system working in common power unit results in higher heating factor of a heat pump and high efficiency of a solar system which finally decreases prime energy demand.
 

Energy Conservation Opportunities: Cement Industry in Iran
Akram Avami, Sourena Sattari

Abstract: Growing concerns arise about energy consumption and its adverse environmental impact in recent years in Iran in which cause manufactures to establish energy management groups. Cement production has been one of the most energy intensive industries in the world. Focusing on energy consumption reduction efforts through process improvement, production management and introducing new technologies can achieve significant results. This study, based on conducting on-site energy audits of over 30 cement firms in Iran during 2004–2005, discovered the following energy-saving potentials: electricity savings of 223.5*106 KWh equivalent to 11.3M$, fuel oil savings of 168*106 Lit equivalent to 39.4M$ in FOB prices. The present paper will study the energy consumption in cement industry in Iran through real auditing and identify technological opportunities in order to decrease energy consumption of the relevant factories, increase the productivity, and improve the production process. Relevant standards planned by government that can provide significant potentials, are discussed too.
 

A dynamically SVC based compact control algorithm for load balancing in distribution systems
A. Kazemi, A. Moradi Koochi and R. Rezaeipour

Abstract: An algorithm for applying a fixed capacitor-thyristorcontrolled reactor (FC-TCR) type of static var compensator (SVC) for dynamically balancing a system is introduced. With a developed individual phase control scheme, an SVC can reduce negativesequence current caused by the load to improve system balancing. In addition, the power factor can be improved simultaneously by selecting an appropriate amount of capacitive/inductive compensation. A compact control algorithm for reactive power compensation and load balancing with the static var compensator (SVC) in three-phase systems is used in this paper. Each phase susceptance of the SVC can be obtained from a very simple function of voltage and power signals which are measured by a three-phase voltage transducer and two single-phase active and reactive power (P-Q) transducers at the load bus. The calculation of compensation susceptances is based on the criterion of a unity power factor and zero sequence currents after compensation. This Method is simulated on the IEEE 13 node system balancing and total harmonic distortion (THD) is studied in unbalanced load node and Substation bus and results is presented.
 

Optimization of Renewable Energy Hybrid System by Minimizing Excess Capacity
Juhari Ab. Razak, Kamaruzzaman Sopian, Yusoff Ali

Abstract: Optimization of renewable energy hybrid system looks into the process of selecting the best components and its sizing with appropriate operation strategy to provide cheap efficient, reliable and cost effective. The technoeconomic analysis usually looks at the cheapest cost of energy produced by of system components while neglecting the excess capacity of the combination. This paper discusses the optimization of the hybrid system in context of minimizing the excess energy and cost of energy. The hybrid of pico hydro, solar, wind and generator and battery as back-up is the basis of assessment. The system configuration of the hybrid is derived based on a theoretical domestic load at a remote location and local solar radiation, wind and water flow rate data. Three demand loads are used in the simulation using HOMER to find the optimum combination and sizing of components. Another set of demand loads is used to investigate the effect of reducing the demand load against the dominant power provider of the system. The results show that the cost of energy can be reduced to about 50% if the demand load is increased to the maximum capacity. Reducing the load to the capacity of the dominant power provider will reduce the cost of energy by 90%.
 

Solar Absorption Refrigeration System Using New Working Fluid Pairs
Jasim M. Abdulateef, Kamaruzzaman Sopian, M. A. Alghoul, Mohd Yusof Sulaiman, Azami Zaharim and Ibrahim Ahmad

Abstract: Absorption refrigeration systems powered by solar energy increasingly attract research interests in the last years. In this study, thermodynamic analyses for different working fluid pairs are performed. A computer simulation model has been developed to predict the performance of solar absorption refrigeration system using different working fluid. The model is based on detailed mass and energy balance and heat and mass transfer for the cycle component. Detailed thermodynamic properties for ammonia- water, ammonia-lithium nitrate and ammonia-sodium thiocyanate are expressed in polynomial equations and used in cycle simulation. The performances of these three cycles against various generator, evaporator, and condenser temperatures are compared. The results show that the ammonia-lithium nitrate and ammonia-sodium thiocyanate cycles give better performance than the ammonia-water cycle. The ammonia-sodium thiocyanate cycle cannot operate at evaporator temperatures below -10°C for the possibility of crystallization. Increasing condenser temperatures cause a decrease in system performance for each cycle. With the increase in evaporator temperature, the COP values for each cycle increase. These results can serve as a source of reference for developing new cycles and searching for new working fluids pairs. They can also be used in selecting operating conditions for existing systems and achieving automatic control for maintain optimum operation of the system.
 

Evaluation Of 1d And 2d Texturing Of Monocrystalline Solar Cell
F. Jahanshah, K. Sopian, I. Ahmad, M. Y. Othman, Azami Zaharim, S. H. Zaidi

Abstract: The performance of solar cell with periodic surface texture pattern was reported. One and two dimensions texturing with the nitride antireflection coating were compared. An I-V tester calibrated by Sandia National Laboratories was used. A 2 cm2 bare monocrystalline silicon solar cell was chosen for comparison. 2D surface texturing showed the best output with maximum short current 0.050 mA. A meteoritic 3D microscope was used to check the textured surface as a non distractive test (NDT).
 

Parametric Analysis Of Multipurpose Solar Adsorption System- Cooling And Heating
M. A. Alghoul, M.Y.Sulaiman, K.Sopian, B.Z. Azmi, M. Abd. Wahab and A. Zaharim

Abstract: A computer simulation program in visual basic was developed to guide in the design of a multipurpose solar continuous adsorption system and predict its applicability under various operating conditions for specific applications with sufficient accuracy is described. Malaysian activated carbons and methanol are used as the adsorbent-adsorbate pair. The most preferable way to popularize such multipurpose solar system in acceptable efficiency, size and cost is based on using efficient activated carbon and heat-sheet collectors as can be shown in the analysis.
 

Heat and Mass Transfer for a Non-Newtonian Fluid Flow along a Surface Embedded in a Porous Medium with Uniform Wall Heat and Mass Fluxes and Heat Generation or Absorption
Ali J. Chamkha

Abstract: The problem of steady, laminar, double-diffusive mixed convective flow of a non-Newtonian power-law fluid past a vertical semi-infinite permeable surface embedded in a porous medium with uniform heat and mass fluxes in the presence of heat generation or absorption effects. A mixed convection parameter for the entire range of free-forced-mixed convection is employed and a set of non-similar equations are obtained. These equations are solved numerically by an efficient implicit, iterative, finite-difference method. The obtained results are checked against previously published work for special cases of the problem and are found to be in good agreement. A parametric study illustrating the influence of the concentration to thermal buoyancy ratio, power-law fluid viscosity index, mixed convection parameter, suction or injection parameter, dimensionless heat generation or absorption parameter and the Lewis number on the local Nusselt and the Sherwood numbers is conducted. The obtained results are shown graphically and the physical aspects of the problem are discussed.
 

        Paper Title, Authors, Abstract (Issue 4, Volume 1, 2007)

Pages

Application of Neural Network to the Cogeneration System by Using Coal
Y. Ozel, I. Guney, and E. Arca

Abstract: Thermodynamic analysis of power plants that generate electricity with the use of coal requires quite a complex and sophisticated mathematical model. In this study relationships between electricity produced in power plant and properties of coal used in cogeneration systems was investigated by using Artificial Neural Network (ANN) with backpropagation learning method. In this method two types of ANN models; single and multi-layer model were used and training with the multi-layer model gave us better result (R2=0,954) than the single layer model which is quite represent the system. The proposed method in this paper does not require complicated calculation and mathematical model with only use coal data.
 

Use of PQV Surface as a Tool for Comparing the Effects of FACTS Devices on Static Voltage Stability
Ali Zare, Ahad Kazemi

Abstract: PV or QV curves are commonly used to determine static voltage stability margin of a power system. Using PV or QV curves has its own advantages, disadvantages and limitations. In this paper, a novel method based on a surface in active power, reactive power and voltage (PQV) space is proposed; and PQV surface has been used for a comprehensive comparison of series and shunt FACTS devices for enhancing static voltage stability. Using this method can show a perfect image of the effects of FACTS devices on voltage stability. By using Power System Analysis Toolbox (PSAT), on the 6-bus test system and the IEEE 14-bus test system, the optimal locations of these controllers are determined. Some of the results obtained by the proposed method are compared with the results obtained by the computation of maximum loading point method. The results of the proposed method are more reasonable
 

Voltage and Current Harmonic Variations in Three-phase Induction Motors with Different Stator Coil Pitches
Yasar Birbir, H. Selcuk Nogay

Abstract: In this study, firstly a sinusoidal pulsewidth modulation (SPWM) inverter feeding five different chorded three-phase induction motors were tested for low-order odd harmonic voltage component and efficiency at different loads. Secondly the motors fed by sine voltage again were tested for low – order odd harmonic voltage and current component and efficiency at different loads. In both two situations; total harmonic distortion (THD) due to 3rd, 5th, 7th, 9th, 11th and 13th harmonics were less in a motor with (1-7) 120o coil pitch at over load. Particular harmonic order for each coil pitch was suppressed and the increasing quantity of efficiency in a motor with (1-6)1000 coil pitch was increased by 4, 92 % fed by PWM and 8, 86 % fed by sine voltage. The full pitch motor with (1-10) 180o coil pitch has more harmonics than other motors.