Cover

Aims and Scope
Editorial Board

1. Atmospheric icing on large wind turbine blades

Muhammad S. Virk¹, Matthew C. Homola², Per J. Nicklasson¹

1 Department of Technology, Narvik University College, 8505 Narvik, Norway.

2 Nordkraft Produksjon, Narvik, Norway.

Abstract: A numerical study of atmospheric ice accretion on a large horizontal axis ‘NREL 5 MW’ wind turbine blade has been carried out using the computational fluid dynamics based technique. Numerical analyses were carried out at five different sections along the wind turbine blade for both rime and glaze ice conditions. Based upon the flow field calculation and the droplet collision efficiency, the rate and shape of accreted ice was simulated at different atmospheric temperatures. Results indicate that the icing is less severe near the blade root sections, where the blade profiles are larger and thicker, both in terms of local ice mass and accreted ice thickness. Change in accreted ice growth with the atmospheric temperature is significant along the blade sections from centre to tip. The research work also highlighted that the ice accretion on wind turbine blades can also be controlled by optimizing its geometric design features instead of only using the energy consuming anti icing and de-icing systems.

Volume 3, Issue 1, 2012, pp.1-8.

2. Optimum sizing of steam turbines for concentrated solar power plants

Andreas Poullikkas, Constantinos Rouvas, Ioannis Hadjipaschalis, George Kourtis

Electricity Authority of Cyprus, P.O. Box 24506, 1399 Nicosia, Cyprus.

Abstract: In this work, a selection of the optimum steam turbine type and size for integration in concentrated solar power (CSP) plants is carried out. In particular, the optimum steam turbine input and output interfaces for a range of CSP plant capacity sizes are identified. Also, efficiency and electricity unit cost curves for various steam turbine capacities are estimated by using a combination of the Steam Pro software module of the Thermoflow Suite 18 package and the IPP v2.1 optimization software tool. The results indicate that the estimated efficiency and the expected specific capital cost of the power block are very important criteria in choosing the best steam turbine size of a CSP plant. For capacity sizes of 10kWe up to 50MWe, the steam turbine efficiency increases and the steam turbine expected specific capital cost of the power block decreases at a high rate, whereas for larger sizes they remain almost constant. Thus, there is significant efficiency gains to be realized and large cost savings in increasing the turbine size up to 50MWe. Finally, although the cost of electricity of a CSP plant with capacities greater than 1MWe is significantly reduced to less than 1US$/kWh, currently such technology can only become economically viable through supporting schemes.

3. Finite time exergoeconomic performance optimization of a thermoacoustic cooler with a complex heat transfer exponent

Lingen Chen¹, Xuxian Kan^1,2,  Feng Wu ^1,2,  Fengrui Sun¹

1 College of Naval Architecture and Power, Naval University of Engineering, Wuhan 430033, P. R. China.

2 School of Science, Wuhan Institute of Technology, Wuhan 430073, P. R. China.

Abstract: The finite time exergoeconomic performance optimization of a generalized irreversible thermoacoustic cooler with heat resistance, heat leakage, relaxation effect, and internal dissipation, in which heat transfer between the working fluid and heat reservoirs obeys a complex generalized heat transfer law (Q proportional delta (Tⁿ)), where n is a complex heat transfer exponent, is investigated in this paper. Both the real part and the imaginary part of the complex heat transfer exponent change the optimal profit rate versus the coefficient of performance (COP) relationship quantitatively. The operation of the generalized irreversible thermoacoustic cooler is viewed as a production process with exergy as its output. The finite time exergoeconomic performance optimization of the generalized irreversible thermoacoustic cooler is performed by taking profit rate as the objective. The analytical formulae about the profit rate and the COP of the thermoacoustic cooler are derived. Furthermore, the comparative analysis of the influences of various factors on the relationship between optimal profit rate and the COP of the generalized irreversible thermoacoustic cooler is carried out by detailed numerical examples. The optimal zone on the performance of the thermoacoustic cooler is obtained.

4. Heat transfer and friction factor characteristics using continuous M shape ribs turbulators at different orientation on absorber plate solar air heater

Sachin Chaudhary¹, Varun¹, Manish Kumar Chauhan²

1 Department of Mechanical Engineering, NIT Hamirpur-177005, India.

2 Department of Mechanical Engineering, College of Engineering Roorkee, Roorkee-247667, India.

Abstract: This paper having more concern with enhancement of heat transfer coefficient using artificial roughened absorber plate on solar air heater. The increment in heat transfer also leads to increase in friction factor which leads to increase in pumping power. In this study M shape geometry has been studied which is having different orientation. The effect of roughness parameters relative roughness height (e/D), relative roughness (P/e) and angle of attack (α) on Nusselt number and friction factor have been seen. The range of Reynolds number 3000-22000, e/D, P/e and α are 0.037-0.0776, 12.5-75 and 30-60° respectively.. It has been found out that providing the artificial roughness of M shape increases heat transfer up to 1.7-1.8 times over the smooth duct.

5. Heat transfer enhancement through inner grooved copper tubes with different tube parameters

M. M. Rahman, Y. M. Ling, G. W. Soon, G. A. Kuan

Department of Mechanical Engineering, Universiti Tenaga Nasional, Putrajaya Campus, 43009 Kajang, Selangor Darul Ehsan, Malaysia.

Abstract: This paper presents the evaluation of heat transfer coefficients for the flow of R22 through internally grooved copper tubes. A series of tests were conducted using two types of tubes namely Tube A and Tube B, which have different tube parameters. The straight and horizontal test section of the test apparatus with a length of 3.67 m was heated or cooled by water circulated in a surrounding annulus. Condensation tests were conducted at mass flux rates of 180 to 537 kg/m2s and the vapor qualities ranged from a nominal value of 83% at the test section inlet to 6% at the outlet. Evaporation tests were conducted at mass flux rates of 110 to 404 kg/m2s and the nominal vapor qualities at the inlet and outlet were 0 and 85%, respectively. For both the condensation and evaporation tests, the heat transfer coefficients are found to increase as the mass flux rate increases.

6. Intake manifold design effect on air fuel mixing and flow for an LPG heavy duty engine

M. A. Jemni, G. Kantchev, M. S. Abid

University of Sfax, National School of Engineers of Sfax (ENIS), Laboratory of Electro-Mechanic Systems (LASEM), B.P. 1173, km 3.5 Soukra, 3038 Sfax, TUNISIA.

Abstract: The paper presents an investigation of mixture preparation in the intake manifold of a Diesel converted engine into LPG spark-ignition engine operation. The formation process of air-LPG (liquefied petroleum gas) mixture was studied using computation fluid dynamics (CFD) mode. Two manifold shapes are used in order to test the adequate design in view of flow and air-gas homogenization. The first is designed according the acoustic-wave-filling phenomena, and the second present an unspecified design. The model of simulation is based on solving Navier-Stokes and energy equations in conjunction with the standard k-ε turbulence model, using the 3D CFD code FloWorks. Experiment test are carried out also to test the intake manifold effect on engine performance. Air-fuel ratio and specific fuel consumption are determined. The results indicate the effectiveness of the first manifold.

7. Performance enhancement of solar module by cooling: An experimental investigation

P G Nikhil, M Premalatha

National Institute of Technology, Tiruchirappalli - 620015, India.

Abstract: The study evaluates the silicone oil cooling of the solar module surface. Solar module with maximum power of 7W was employed for cooling. This paper summarizes the result of an outdoor experiment. The experiments were conducted in batch mode, with the cooling medium spread on the module surface at different thickness from 0mm to 6mm. The performance of the module, throughout the day, for different thickness of the medium is reported. The study also presents a mathematical model, predicting the variation of the maximum power when the module surface is cooled using silicone oil. The results of the equation model are compared and validated with the experimental as well as with results reported in the earlier works. The cooling contributes to appreciable improvement in the module efficiency to above 20%.

8. Thermal evaluation of a sun tracking solar cooker

Yousif El-Tous¹, Omar. O. Badran², Anwar Al-Mofleh³

1,3 Department of Electrical Engineering, Faculty of engineering Technology, Al-Balqa’ Applied University, P.O.Box 15008, Amman, Jordan.

2 Department of Mechanical Engineering, Faculty of engineering Technology, Al-Balqa Applied University, P.O.Box 15008, Amman, Jordan.

Abstract: Solar energy is one of many important types of renewable energy. Jordan is of great needs for renewable energy systems applications since it depends totally in generation of its required energy on imported oil. This study is an experimental work of tracking system developed for enhancing the solar heating using solar cooker. An electronic sun tracking device was used for rotating the solar heater with the movement of the sun. A comparison between fixed and sun tracked cooker showed that the use of sun tracking increased the heating temperature by 36% due to the increase in radiation concentration and using internal mirror reflectors. The programming method used for tracking control works efficiently in all weather conditions regardless of the presence of clouds. It can be used as backup control circuit in which relays are the essential control devices.

9. Purpose of neuronal method for modeling of solar collector

 Omari Tariq^1,2,3, Hanini Salah¹, Cherif Si Moussa¹, Hamid Abdi²

1 LBMPT, Université Yahia Fares de Médéa, Quartier Ain D'Heb, 26000, Médéa, Algérie.

2 SEES/MS, B.P. 478, Route de Reggane, Adrar, Algérie.

3 Unité de développement des équipements solaires, Bou-Ismaïl, Tipaza, Algérie.

Abstract: Artificial Neural Networks (ANN) are widely accepted as a technology offering an alternative way to tackle complex and ill-defined problems. They have been used in diverse applications and have shown to be particularly effective in system identification and modeling as they are fault tolerant and can learn from examples. On the other hand, ANN are able to deal with non-linear problems and once trained can perform prediction at high speed. The objective of this work is the characterization of the integrated collector-storage solar water heater (ICSSWH) by the determination of the day time thermal (and optical) properties, and Night time heat loss coefficient with experimental temperatures, and predictive temperatures by (ANN). Because of that, an ANN has been trained using data for three types of systems, all employing the same collector panel under varying weather conditions. In this way the network was trained to accept and handle a number of unusual cases. The data presented as input were, the working systems (day or night), the type of system, the year, the month, the day, the time, the ambient air temperature, and the solar radiation. The network output is the temperature of the four tanks of storage unit. The correlations coefficients (R2 –value) obtained for the training data set was equal to 0.997, 0.998, 0.998, and 0.996 for the four temperatures of each tank. The results obtained in this work indicate that the proposed method can successfully be used for the characterization of the ICSSWH.

10. An investigation on the performance characteristics of solar flat plate collector with different selective surface coatings

Madhukeshwara. N¹, E. S. Prakash²

1 Department of Mechanical Engineering, B.I.E.T, Davanagere, Karnataka, India.

2 Department of Studies in Mechanical Engineering, U.B.D.T.C.E, Davanagere, Karnataka, India.

Abstract: In the present work, investigations are made to study performance characteristics of solar flat plate collector with different selective surface coatings. Flat plate collector is one of the important solar energy trapping device which uses air or water as working fluid. Of the many solar collector concepts presently being developed, the relative simple flat plate solar collector has found the widest application so far. Its characteristics are known, and compared with other collector types, it is the easiest and least expensive to fabricate, install, and maintain. Moreover, it is capable of using both the diffuse and the direct beam solar radiation. For residential and commercial use, flat plate collectors can produce heat at sufficiently high temperatures to heat swimming pools, domestic hot water, and buildings; they also can operate a cooling unit, particularly if the incident sunlight is increased by the use of reflector. Temperatures up to 70 C are easily attained by flat plate collectors. With very careful engineering using special surfaces, reflectors to increase the incident radiation and heat resistant materials, higher operating temperatures are feasible.

11. Unsteady hydromagnetic convective flow past an infinite vertical porous flat plate in a porous medium

S. S. Das¹, M. Maity², J. K. DAS³

1 Department of Physics, KBDAV College, Nirakarpur, Khurda-752 019 (Orissa), India.

2 Department of Physics, Suddhananda Residential Polytechnic, Bhatapatna, Phulnakhara, Cuttack-
752 115 (Orissa), India.

3 Department of Physics, Stewart Science College, Mission Road, Cuttack-753 001(Orissa), India.

Abstract: This paper theoretically investigates the unsteady free convective flow of a viscous incompressible electrically conducting fluid past an infinite vertical porous flat plate in a porous medium with constant suction in presence of a uniform transverse magnetic field. The governing equations of the flow field are solved using multi parameter perturbation technique and approximate solutions for velocity, temperature, skin friction and rate of heat transfer are obtained. The effects of the various flow parameters characterizing the flow field are analyzed with the help of figures and table. It is observed that a growing magnetic parameter M or permeability parameter Kp decelerates the transient velocity of the flow field at all points, while a growing Grashof number for heat transfer Gr accelerates the transient velocity at all points. Further, the effect of growing Prandtl number Pr is to diminish the transient temperature of the flow field at all points and on the other hand, the permeability parameter reverses the effect. The permeability parameter Kp enhances the skin friction as well as the rate of heat transfer at the wall and the magnetic parameter shows the reverse effect.

12. Development of MCESC software for selecting the best stormwater erosion and sediment control measure in Malaysian construction sites

Ibrahiem Abdul Razak Al-Hadu¹, Lariyah Mohd Sidek¹, Mohamed Nor Mohamed Desa², Noor Ezlin Ahmad Basri²

1 Civil Engineering, Universiti Tenaga Nasional, Kajang, Selangor, Malaysia.

2 Civil & Structural Engineering, Universiti Kebangsaan Malaysia, Bangi, Selangor, Malaysia.

Abstract: Malaysia located in a tropical region which is interested with a heavy rainfall through the whole seasons of the year. Construction stages usually associated with soil disturbing due to land clearing and grading activities, this combined with the tropical climate in Malaysia, will generate an enormous amount of soil to be eroded and then deposited into the adjacent water bodies. There are many kinds of mitigation measures used so as to reduce the impact of erosion and sedimentation that are generated due to the stormwater in construction sites. This paper aims to develop and apply Multi Criteria Analysis (MCA) software called Multi Criteria Erosion and Sediment Control (MCESC) software in which it can be applied in selecting the best stormwater control measure by depending on specified criteria and criterion weight. Visual Basic 6 was adopted as a development tool. This software can help the engineers, contractors on site and decision makers to find the best stormwater control measure in any construction site in Malaysia. Users of the MCESC software are given the opportunity to select the best stormwater control measure via expert’s judgments that are built in the system or via their own expertise.  MCESC software has many benefits since the experts are not always available and the consultancy is a costly issue which add further financial allocations to the project.

13. Economical hydrogen production by electrolysis using nano pulsed DC

Dharmaraj C.H ¹, AdishKumar S.²

1 Tangedco, Tirunelveli, ME Environmental Engineering.

2 Department of Civil Engineering, Anna University of Technology Tirunelveli, Tirunelveli -627007, India.

Abstract: Hydrogen is an alternate renewable eco fuel. The environmental friendly hydrogen production method is electrolysis. The cost of electrical energy input is major role while fixing hydrogen cost in the conventional direct current Electrolysis. Using nano pulse DC input make the input power less and economical hydrogen production can be established. In this investigation, a lab scale electrolytic cell developed and 0.58 mL/sec hydrogen/oxygen output is obtained using conventional and nano pulsed DC. The result shows that the nano pulsed DC gives 96.8 % energy saving

14. Effects of temperature dependence of thermoelectric properties on the power and efficiency of a multielement thermoelectric generator

Fankai Meng, Lingen Chen, Fengrui Sun

College of Naval Architecture and Power, Naval University of Engineering, Wuhan 430033, P. R. China.

Abstract: Taking temperature dependence of thermoelectric properties and external heat transfer irreversibility into account synchronously, an improved finite time thermodynamic model of a multi-element thermoelectric generator is established. The theoretical iterative functions of the hot and cold junction temperatures are obtained. The model is applied to the analysis of a multi-element thermoelectric generator, which is made of typical thermoelectric materials. The effects of output electrical current, length of thermoelectric element and ratio of thermal conductance allocation of heat exchangers on the power and efficiency are analyzed, along with the optimal variables. Comparing this temperature dependent model with the traditional temperature independent model, it is found that the temperature dependence of thermoelectric properties has significant effects on the power, efficiency and optimal variables. Specially, for a large temperature difference, the temperature independent model will cause a considerable error, so it is recommended to apply this temperature dependent model for the analysis of practical thermoelectric generator. Because of the effects of temperature dependence of thermoelectric properties, a limit of efficiency of about 7% can not be overrun. The model and calculation method provided in this paper may be applied to not only the calculation, prediction but also the design and optimization of thermoelectric generators.

15. Vibration signatures of a biodiesel fueled CI engine and effect of engine parameters

S. Jindal

College of Technology & Engineering, Maharana Pratap University of Agriculture and Technology, Udaipur - 313001, India.

Abstract: With increasing emphasis on use of biodiesel in compression ignition engines, the long term effects are yet to be evaluated. Through many studies, the suitability of biodiesel blends upto 20% are well established and are being adopted by many organizations with recommended use of biodiesel. But in all of these studies the combustion and emission evaluations are the main characteristics which received the attention of researchers and the objectives targeted are good performance and low emissions. The long term effects are difficult to be assessed as it requires long time as well as consistent conditions of operation. A short route is suggested in this study using the vibration signatures of the engine cylinder and head vibrations. The comparison between the vibration signatures of an engine fueled with diesel and biodiesel blends under different compression ratio and injection pressures show significant changes in the vibration patterns and the difference can be used to asses the long term effects. The method is based on fundamental relationship between the engines vibration pattern and the relative characteristics of the combustion process under different operating conditions.

VIENNA INTERNATIONAL CONFERENCES - FEBRUARY 2012.