Cover

Aims and Scope
Editorial Board

1. Intrusion problematic during water supply systems’ operation

Jesús Mora-Rodríguez¹, P. Amparo López-Jiménez¹ , Helena M. Ramos²

1 Departamento de Ingeniería Hidráulica y Medio Ambiente, Universidad Politécnica de Valencia, Camino de Vera, s/n, 46022, Valencia, España.

2 Civil Engineering Department and CEHIDRO, Instituto Superior Técnico, Technical University of Lisbon, Av. Rovisco Pais, 1049-001, Lisbon, Portugal.

Abstract: Intrusion through leaks occurrence is a phenomenon when external fluid comes into water pipe systems. This phenomenon can cause contamination problems in drinking pipe systems. Hence, this paper focuses on the entry of external fluids across small leaks during normal operation conditions. This situation is especially important in elevated points of the pipe profile. Pressure variations can origin water volume losses and intrusion of contaminants into the drinking water pipes. This work focuses in obtaining up the physical representation on a specific case intrusion in a pipe water system. The combination of two factors is required to generate this kind of intrusion in a water supply system: on one hand the existence of at least a leak in the system; on the other hand, a pressure variation could occur during the operation of the system due to consumption variation, pump start-up or shutdown. The potential of intrusion during a dynamic or transient event is here analyzed. To obtain this objective an experimental case study of pressure transient scenario is analyzed with a small leak located nearby the transient source.

Volume 2, Issue 3, 2011, pp.391-400.

2. Numerical simulation and performance test of metal hydride hydrogen storage system

Tzu-Hsiang Yen¹, Bin-Hao Chen², Bao-Dong Chen¹

1 Refining & Manufacturing Research Institute, CPC Corporation, Chia-Yi City 60036, Taiwan, ROC.

2 Industrial Technology Research Institute, Energy and Environment Laboratories, C600, Rm. 511, No. 8, Gongyan Rd., Liujia Shiang, Taiwan County, Taiwan, ROC.

Abstract: Metal hydride reactors are widely used in many industrial applications, such as hydrogen storage, thermal compression, heat pump, etc. According to the research requirement of metal hydride hydrogen storage, the thermal analyses have been implemented in the paper. The metal hydride reaction beds are considered as coupled cylindrical tube modules which combine the chemical absorption and desorption in metal hydride. The model is then used metal hydride LaNi5 as an example to predict the performance of metal hydride hydrogen storage devices, such as the position of hydration front and the thermal flux. Under the different boundary condition the characteristics of heat transfer and mass transfer in metal hydride have influence on the hydrogen absorption and desorption. The researches revealed that the scroll design can improve the temperature distribution in the reactor and the porous tube for directing hydrogen can increase the penetration depth of hydride reaction to decrease the hydrogen absorption time.

3. CO2e emissions from HVAC equipment and lifetime operation for common U.S. building types

Aik Jong Tan, Darin W. Nutter

Department of Mechanical Engineering, University of Arkansas, Fayetteville, AR 72701, USA.

Abstract: Greenhouse gas emissions associated with the lifetime operational energy use and equipment manufacture of the heating, ventilating, and air-conditioning equipment for ten common commercial building types were presented. The influence of operating the building in several different climate regions were included in the analysis. Emission factors for natural gas and each of the three North American Electric Reliability Corporation major interconnections were used. Results found emissions associated with a building’s lifetime operational energy use were dominant compared to those from the equipment manufacture and production which ranged from 1.9 – 4.2%. Primary factors that influenced the emission rates were found to be regional electrical emission factors, building type, and climate.

4. Assessment of pretreatments and enzymatic hydrolysis of wheat straw as a sugar source for bioprocess industry

Bohdan Volynets, Yaser Dahman

Department of Chemical Engineering, Ryerson University, Toronto, Ontario, Canada.

Abstract: Environmental concerns and rising oil prices have led to development of biofuels from crop residue lignocelluloses, among which wheat straw is an important feedstock used in leading commercial bioethanol processes. Lignocellulose is structured in a way that makes direct bioconversion of biomass into sugars by hydrolytic enzymes difficult and unfeasible, requiring a pretreatment step. Common biomass pretreatment technologies are assessed for potential application in obtaining fermentable sugars of wheat straw. Current outlook, challenges and opportunities on enzymatic hydrolysis of lignocellulose are also presented.

5. Carbon emission patterns in different income countries

Kai Wang¹, Le-Le Zou², Jie Guo³, Wen-Jing Yi², Zhen-Hua Feng³, Yi-Ming Wei^4,5

1 Research Institute of Petroleum Exploration & Development, PetroChina, Beijing, 100083, China.

2 Institute of Policy and Management, Chinese Academy of Sciences, Beijing, 100190, China.

3 School of Management, University of Science and Technology of China, Hefei, 230026, China.

4 Center for Energy and Environmental Policy Research, Beijing Institute of Technology, Beijing, 100081, China.

5 School of Management and Economics, Beijing Institute of Technology, Beijing, 100081, China.

Abstract: In order to find the main driving forces affecting CO₂ emission patterns and the relationship between economic development and CO₂ emissions, this paper uses models of -convergence, absolute Beta-convergence and conditional Beta-convergence to analyze the inner characteristics of CO₂ emissions and the income level of 128 countries (and regions) in the world. The countries (and regions) are divided into 5 groups based on their per capita income levels. The results show that in the past 40 years, all the groups showed trends of convergence on the CO₂ emissions. In terms of emission levels, lagging countries (and regions) tend to catch up with advanced nations, with convergence tending to be conditional on country-specific characteristics such as energy use and energy structures rather than absolute convergence. Then this paper examines the impacts of selected variables such as GDP per capita, population, oil, gas, coal etc. on the emission trends. The analysis on the impacting factors shows that for the developing countries (and regions), the levels of economic development have greater effects on their carbon emissions patterns. And for the developed countries (and regions), the energy consumption structures wielded a big influence for the past 40 years. We find that the growth speed of CO₂ emissions in developed countries (and regions) would get slower, and those of the developing countries (and regions) give expression to catching-up effects. These findings are expected to shed a light on the global policy making in coping climate change.

6. Exergoeconomic optimization and improvement of a cogeneration system modeled in a process simulator using direct search and evolutionary methods

Alexandre S. Cordeiro¹, Leonardo S. Vieira², Manuel E. Cruz³

1 UFRJ – Federal University of Rio de Janeiro, Department of Mechanical Engineering, COPPE/Politecnica, CP 68503, CT, Cidade Universitaria, Rio de Janeiro, RJ, 21945-970, Brazil.

2 CEPEL – Electrical Energy Research Center, Special Technologies Department, CP 68007, Av. Hum s/n, Cidade Universitaria, Rio de Janeiro, RJ, 21944-970, Brazil.

3 UFRJ – Federal University of Rio de Janeiro, Department of Mechanical Engineering, COPPE/Politecnica, CP 68503, CT, Cidade Universitaria, Rio de Janeiro, RJ, 21945-970, Brazil.

Abstract: The optimal design and operation of energy systems are critical tasks to sustain economic growth and reduce environmental impacts. In this context, this paper presents the mathematical optimization and exergoeconomic improvement of an energy system modeled in a professional thermodynamic process simulator using the direct search method of Powell and an evolutionary stochastic method of the genetic type. In the mathematical optimization approach, as usual, the minimum system total cost is sought by simultaneous manipulation of the entire set of decision variables. At times, the global minimum is not exactly reached. On the other hand, the exergoeconomic improvement methodology determines, based on the exergetic and economic analyses of the system at each iteration, a subset of most significant decision variables which should be modified for each component, and applies an optimization algorithm to these variables only. In the improvement process an appreciable reduction, not strict minimization, of the system total cost is sought. The energy system analyzed is a 24-component cogeneration plant, denoted CP-24, which is representative of complex industrial installations. As opposed to a conventional optimization approach, the integrated optimization with a professional process simulator eliminates the necessity to implement explicitly the constraints associated with the physical and thermodynamic models of the system. Therefore, the integrated strategy can tackle large systems, and ought to be more easily applied by practicing energy engineers. The results obtained permit, first, to compare the performance of mathematical optimization algorithms belonging to different classes, and, second, to evaluate the effectiveness of the iterative exergoeconomic improvement methodology working with these algorithms.

7. The effect of EGR rates on NOX and smoke emissions of an IDI diesel engine fuelled with Jatropha biodiesel blends

M. Gomaa, A.J. Alimin, K.A. Kamarudin

Faculty of Mechanical and Manufacturing Engineering, Universiti Tun Hussein Onn Malaysia (UTHM) 86400 Parit Raja, Batu Pahat, Johor, Malaysia.

Abstract: The depletion of fossil fuels and the worst impact on environmental pollution caused of their burning have led to the search for renewable clean energies. Nowadays, there are many sources of renewable energy.  Biodiesel is just one source, but a very important one. Biodiesel has been known as an attractive alternative fuel although biodiesel produced from edible oil is very expensive than conventional diesel. Therefore, the uses of biodiesel produced from non-edible oils are much better option. Currently Jatropha biodiesel (JBD) is receiving attention as an alternative fuel for diesel engine. However, previous studies have reported that combustion of JBD emitted higher nitrogen oxides (NOX), while hydrocarbon (HC) and smoke emissions were lower than conventional diesel fuel. Exhaust gas recirculation (EGR) is one of the techniques being used to reduce NOX emission from diesel engines; because it decreases both flame temperature and oxygen concentration in the combustion chamber. Some studies succeeded to reduce NOX emission from biodiesel fuelled engines using EGR; but they observed increase in smoke emission with increasing engine load and EGR rate. The aim of the present work is to investigate the effect of EGR on an indirect injection (IDI) diesel engine fuelled with JBD blends in order to reduce NOX and smoke emissions. A 4-cylinder, water-cooled, turbocharged, IDI diesel engine was used for investigation. Smoke, NOX, carbon monoxide (CO) and carbon dioxide (CO2) emissions were recorded and various engine performance parameters were also evaluated. The results showed that, at 5% EGR with JB5, both NOX and smoke opacity were reduced by 27% and 17% respectively. Furthermore, JB20 along with 10% EGR was also able to reduce both NOX and smoke emission by 36% and 31%, respectively compared to diesel fuel without EGR.

8. Spatial moment analysis of colloid facilitated radionuclide transport in a coupled fracture-matrix system

N. Natarajan^{1, G. Suresh Kumar2}

1 EWRE Division, Department of Civil Engineering, Indian Institute of Technology – Madras, Chennai 36, India.

2 Department of Ocean Engineering,  Indian Institute of Technology – Madras, Chennai-36, India.

Abstract: A numerical model is developed for studying the transport of colloid facilitated radionuclide transport in a coupled fracture-matrix system. The radionuclides and the colloids are assumed to decay, sorb on the fracture surface, as well as diffuse into the rock matrix. The sorption of the radionuclides onto the mobile and immobile colloids within the fracture is assumed to be linear. The governing equations describing the radionuclide and colloidal transport along the fracture axis and diffusive mass transport within the rock matrix, which is normal to the fracture axis are coupled together, while maintaining the continuity of fluxes at the fracture-matrix interface. Constant concentration is assumed at the inlet of the fracture for both colloids as well as radionuclides and varying grid is adopted at the fracture and rock-matrix interface to capture the flux transfer. Spatial moments are performed on the concentration profiles of the radionuclides in order to investigate the impact on the mobility and dispersion behavior of the radionuclides. Results suggest that a combination of fluid velocity and colloidal velocity, which influences the residence time of radionuclides within the fracture (against sorption onto the fracture walls, diffusion into the rock-matrix and sorption onto the colloids) ultimately decides the mobility of radionuclides. The presence of colloids retards the mobility of radionuclides in the aqueous phase. The presence of colloids have reduced the mixing of radionuclides within the fractures significantly as against the mixing experienced in a coupled fracture-matrix system in the absence of colloidal transport.

9. Noise evaluation of automotive A/C compressor

Sameh M.  Metwally, Mohamed I. Khalil, Shawki A. Abouel-seoud

Automotive and Tractors Dept., Faculty of Engineering, Helwan University, Cairo, Egypt.

Abstract: Passenger compartment's interior noise and thermal performance are essential criteria for the driving comfort of vehicles. The air-conditioning system influences both field of comfort. It creates comfortable thermal conditions. On the other hand, the noise radiation of the air-condition system's components can be annoying. The blower, the air distribution ducts and the registers affect air rush noise. In some cases, the refrigerant flow creates hissing noise.  Such noise has a great influence on vehicle acoustical comfort and on overall quality perception of a vehicle Therefore, the acoustic performance of air-condition compressors become more important for passenger comfort. At engine idling and at extreme temperatures the air-condition compressor can be audible as the significant sound source. However, the aim of this paper is to quantify air-borne noise characteristics of vehicle air-condition compressor. A simulated experimental model comprises a small wooden box with dimensions of 0.5 x 0.5 x 0.5 m represented the principle of hemi-anechoic room was designed and acoustic characteristics of the sound field inside the box were determined. The air-condition compressor characteristics parameters considered in this paper are fan position and electric motor speed. In addition, a single number of the air column natural frequency is calculated. The results indicate that significant information can be obtained in order to investigate the vehicle air-condition compressor and consequently improve the vehicle interior quietness.

10. Renewable energy scenario and disregarded petition of rural populace of an Indian island: A critical survey and concept of an inexpensive artifact

Tamal Ghosh, Saswata Nath, Tanmoy Chakraborty, Pranab K Dan

Department of Industrial Engineering and Management, West Bengal University of Technology, BF 142, Sector 1, Salt Lake City, Kolkata, India.

Abstract: This study attempts to establish the challenges associated to solar energy scenario in rural living of south-east of Indian province namely West Bengal and to suggest an inexpensive solar artifact with an aim to cater to the areas which are scarcely electrified and primarily in countryside. Stockpile of fossil fuels are depleting and there is an urgent need of promoting renewable energy products that can pertinently be supported by this clean energy. Renewable energy is alternate source of energy or non-conventional energy such as, solar energy, water energy, wind energy, biomass and bio-gas energy, tidal energy, Geo-thermal energy, hydrogen energy. Scope of this article converges on disregarded demand scenario of rural inhabitants and fostering inexpensive appropriate solar technology based product. For subsequent investigation a critical socio-technical survey has also been conducted in the rural Sundarban area of Southern part of West Bengal, with an aim to acquire the glimpse of the presently operating government project on solar technology and to identify the demand and solar product there for.

11. Development of bioenergy conversion alternatives for climate change mitigation

Nana S.A. Derkyi¹, Daniel Sekyere¹, Philip Y. Okyere², Nicholas A. Darkwa³, Samuel K. Nketiah⁴

1 CSIR-FORIG, Kwame Nkrumah University of Science and Technology KNUST Box 63, Ghana.

2 Electrical Engineering Department, Kwame Nkrumah University of Science and Technology KNUST, Ghana.

3 FRNR, Kwame Nkrumah University of Science and Technology KNUST, Ghana.

4 TROPENBOS International, Ghana.

Abstract: Traditional charcoal production, firewood sourcing and over-dependence on the national grid for electricity are associated with high greenhouse gas emissions relative to other common energy options. However, there have been few attempts to analyze the potential of cogeneration and briquetting as favourable energy options for climate change mitigation. The possibility of utilizing abundant wood residues to produce energy for domestic and industrial application through co-generation and sawdust briquetting was assessed. Annual residues generated in the three mills studied ranged from 19,230 m3 to 32,610 m3. Annual output of semi-carbonized and carbonized sawdust briquette from the briquette factory studied was 1400 tonnes. Heating values of the wood species ranged from 8.2 to 20.3 MJ/kg. Power requirements for the mills, necessary for sizing co-generation units were derived from their monthly electricity bills. Power ratings for co-generation units were specified between 400 kWe to 2000 kWe with heat to power ratios of 19 to 21. The energy generated could be used to produce electrical power and reduce dependency on the national grid. Conversion of sawdust in the briquette factory potentially contributes a saving of 5,600 tonnes of trees/year that would have been cut from the forest. Thus, adoption of co-generation and sawdust briquetting nationwide could be of immense benefit to the country in terms of climate change mitigation.

12. Study of oxidation stability of Jatropha curcas biodiesel/ diesel blends

Siddharth Jain, M.P. Sharma

Biofuel Research Laboratory, Alternate Hydro Energy Centre, Indian Institute of Technology Roorkee, Uttarakhand- 247667,India.

Abstract: Biodiesel production is undergoing rapid technological reforms in industries and academia. This has become more obvious and relevant since the recent increase in the petroleum prices and the growing awareness relating to the environmental consequences of the fuel overdependency. However, the possibilities of production of biodiesel from edible oil resources in India is almost impossible, as primary need is to first meet the demand of edible oil that is already imported therefore it is essential to explore non-edible seed oils, like Jatropha curcas and Pongamia as biodiesel raw materials. The oxidation stability of biodiesel from Jatropha curcas oil is very poor. Therefore the aim of the present paper is to study the oxidation stability of Jatropha curcas biodiesel/ diesel blend. Also the effectiveness of various antioxidants is checked with respect to various blends of biodiesel with diesel.

13. Reducing the vehicles fuel consumption by using the optimization technique

Mohamed I. Khalil

Faculty of Engineering – Mataria, Automotive & Tractor Dept., Helwan University, Egypt.

Abstract: Most modern searches are directed to alternative fuels and hybrid vehicles because the buffer stock from the petroleum oils reduces with time. On the other hand, there are millions from vehicles that already operates by petrol and diesel engines and not logic the searches neglect all these vehicles. This paper presents a solution of reducing fuel consumption for a branch from these vehicles especially works in public transport companies whereas these companies almost have thousands from the vehicles and these companies exist in all countries. The vehicles fuel consumption is function in the travelled kilometres. The aim of this paper reduces the fuel consumption of the public transport companies by minimizing the non-productive distance, where the non-productive distance are the distance between garages and first bus station to start the trip and inverse. The proposed model is based on using the transportation technique for minimizing the total non-productive distance by redistribution the vehicles of these companies on their garages. Using this model is powerful for minimizing the running cost of public transport companies, addition to reducing the bus emission and saving the energy. The results indicate that significant information gained for minimizing the total non-productive distance by redistribution the vehicles on garages that will save the extra driving that helps for saving the fuel consumption, oil consumption, spare parts,.., and reducing the emission and the congestion traffic problem.

14. Investigations in gasification of biomass mixtures using thermodynamic equilibrium and semi–equilibrium models

Buljit Buragohain, Pinakeswar Mahanta and Vijayanand S. Moholkar

Center for Energy, Indian Institute of Technology Guwahati, Guwahati – 781 039, Assam, India.

Abstract: Biomass gasifiers with power generation capacities exceeding 1 MW have large biomass consumption. Availability of a single biomass in such large quantities is rather difficult, and hence, mixtures of biomasses need to be used as feed–stock for these gasifiers. This study has assessed feasibility of biomass mixtures as fuel in biomass gasifiers for decentralized power generation using thermodynamic equilibrium and semi–equilibrium (with limited carbon conversion) model employing Gibbs energy minimization. Binary mixtures of common biomasses found in northeastern states of India such as rice husk, bamboo dust and saw dust have been taken for analysis. The potential for power generation from gasifier has been evaluated on the basis of net yield (in Nm3) and LHV (in MJ/Nm3) of the producer gas obtained from gasification of 100 g of biomass mixture. The results of simulations have revealed interesting trends in performance of gasifiers with operating parameters such as air ratio, temperature of gasification and composition of the biomass mixture. For all biomass mixtures, the optimum air ratio is ~ 0.3 with gasification temperature of 800oC. Under total equilibrium conditions, and for engine–generator efficiency of 30%, the least possible fuel consumption is found to be 0.8 kg/kW–h. As revealed in the simulations with semi–equilibrium model, this parameter shows an inverse variation with the extent of carbon conversion. For low carbon conversions (~ 60% or so), the specific fuel consumption could be as high as 1.5 kg/kW–h. The results of this study have also been compared with previous literature (theoretical as well as experimental) and good agreement has been found. This study, thus, has demonstrated potential of replacement of a single biomass fuel in the gasifier with mixtures of different biomasses.

15. A Z-source single phase matrix converter with safe commutation strategy

P. Deivasundari , V. Jamuna

Jerusalem College of Engg. Chennai, India.

Abstract: This paper presents a type of converter that can buck and boost with step-changed frequency called a Single-Phase Z-Source Buck-Boost Matrix Converter. It employs a safe-commutation strategy which results in the elimination of voltage spikes on switches without the need of a snubber circuit. This is facilitated through proper switching control algorithm. The operating principles of this converter are described and the circuit behaviour is confirmed by MATLAB / Simulink simulation results.