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Aims and Scope
Editorial Board

1. Mechanical behaviour of membrane electrode assembly (MEA) during cold start of PEM fuel cell from subzero environment temperature

Maher A.R. Sadiq Al-Baghdadi

Fuel Cell Research Center, International Energy and Environment Foundation, Najaf, P.O.Box 39, Iraq.

Abstract: Durability is one of the most critical remaining issues impeding successful commercialization of broad PEM fuel cell transportation energy applications. Automotive fuel cells are likely to operate with neat hydrogen under load-following or load-levelled modes and be expected to withstand variations in environmental conditions, particularly in the context of temperature and atmospheric composition. In addition, they are also required to survive over the course of their expected operational lifetimes i.e., around 5,500 hrs, while undergoing as many as 30,000 startup/shutdown cycles. Cold start capability and survivability of proton exchange membrane fuel cells (PEM) in a subzero environment temperature remain a challenge for automotive applications. A key component of increasing the durability of PEM fuel cells is studying the behaviour of the membrane electrode assembly (MEA) at the heart of the fuel cell. The present work investigates how the mechanical behaviour of MEA are influenced during cold start of the PEM fuel cell from subzero environment temperatures. Full three-dimensional, non-isothermal computational fluid dynamics model of a PEM fuel cell has been developed to simulate the stresses inside the PEM fuel cell, which are occurring during fuel cell assembly (bolt assembling), and the stresses arise during fuel cell running due to the changes of temperature and relative humidity. The model is shown to be able to understand the many interacting, complex electrochemical, transport phenomena, and stresses distribution that have limited experimental data.

Volume 6, Issue 2, 2015, pp.107-114.

2. Updated equation to compute the soil voltage contour under fault condition

M. Nassereddine, J. Rizk, M. Nagrial, A. Hellany

School of Computing, Engineering & Mathematics, University of Western Sydney, Australia.

Abstract: The neighboring rates between high voltage substation and residential buildings are amplified due to populations increase. Under fault or system malfunction, earth potential rise could reach an unsafe condition. This earth potential rise extends to the surrounding soil and known as the soil voltage. To guarantee safety acquiescence of the new system, earthing system design is required. Earthing system offers a safe working atmosphere for employees and people transitory by during a fault or malfunction of a power system. The soil voltage due to high voltage EPR plays important roles when it comes to step and touch voltage computation. In this paper, a new equation is studied to compute the soil voltage at distance x from the fault location. Numerous field tests is included to verify the proposed method.

3. Analytical and numerical thermal buckling analysis investigation of unidirectional and woven reinforcement composite plate structural

Muhannad Al-Waily

Mechanical Engineering department, Faculty of Engineering, Al-Kufa University, Ministry of Higher Education & Scientific Research, Iraq.

Abstract: In this study, evaluated of the critical thermal effect caused the buckling of unidirectional and woven composite plate with different aspect ratio of plate combined from different types of long and woven reinforcement fiber and different resin material types. The thermal buckling analysis by using theoretical analysis with solution the general equation of motion of orthotropic composite simply supported plate with buckling thermal effect and evaluated the effect of reinforcement type and resin types on the buckling temperature with effect of volume fraction of reinforcement fiber and resin materials. In addition to, analysis the problem of thermal buckling by numerical study with using finite element method and compare the results of numerical analysis with theoretical results of thermal bucking plate and evaluated the agreement between the two methods used. The results are the critical thermal buckling temperature of orthotropic composite plate with effect of different reinforcement fiber as unidirectional or woven fiber and different resin materials with various volume fraction of reinforcement fiber and effect of aspect ratio of composite plate and compare of critical temperature with different reinforcement types. In addition to compare between the theoretical and numerical analysis and evaluated the maximum percent error about (3.5%). And, the results showed that the critical temperature buckling of unidirectional reinforcement fiber more than critical bucking temperature of woven reinforcement fiber and the buckling temperature increasing with increase the volume fraction of reinforcement fiber.

4. Linear irreversible thermodynamic performance analyses for a generalized irreversible thermal Brownian refrigerator

Zemin Ding^1,2,3, Lingen Chen^1,2,3, Yanlin Ge^1,2,3, Fengrui Sun^1,2,3

1 Institute of Thermal Science and Power Engineering, Naval University of Engineering, Wuhan 430033, China.

2 Military Key Laboratory for Naval Ship Power Engineering, Naval University of Engineering, Wuhan 430033, China.

3 College of Power Engineering, Naval University of Engineering, Wuhan 430033, China.

Abstract: On the basis of a generalized model of irreversible thermal Brownian refrigerator, the Onsager coefficients and the analytical expressions for maximum coefficient of performance (COP) and the COP at maximum cooling load are derived by using the theory of linear irreversible thermodynamics (LIT). The influences of heat leakage and the heat flow via the kinetic energy change of the particles on the LIT performance of the refrigerator are analyzed. It is shown that when the two kinds of irreversible heat flows are ignored, the Brownian refrigerator is built with the condition of tight coupling between fluxes and forces and it will operate in a reversible regime with zero entropy generation. Moreover, the results obtained by using the LIT theory are compared with those obtained by using the theory of finite time thermodynamics (FTT). It is found that connection between the LIT and FTT performances of the refrigerator can be interpreted by the coupling strength, and the theory of LIT and FTT can be used in a complementary way to analyze in detail the performance of the irreversible thermal Brownian refrigerators. Due to the consideration of several irreversibilities in the model, the results obtained about the Brownian refrigerator are of general significance and can be used to analyze the performance of several different kinds of Brownian refrigerators.

5. Optimization of long-term performance of municipal solid waste management system: A bi-objective mathematical model

Hao Yu¹, Wei Deng Solvang¹, Shiyun Li^1,2

1 Department of Industrial Engineering, Narvik University College, Postboks 385 Lodve gate 2, 8505 Narvik, Norway.

2 College of Mechanical Engineering, Zhejiang University of Technology, No. 18 Caowang Road, 310016 Hangzhou, P.R.China.

Abstract: Management of municipal solid waste has becoming an extremely important topic for any urban authorities in recent years due to the rapidly increasing solid waste quantity and potential environmental pollution. In this paper, a bi-objective dynamic linear programming model is developed for decision making and supporting in the long-term operation of municipal solid waste management system. The proposed mathematical model simultaneously accounts both economic efficiency and environmental pollution of municipal solid waste management system over several time periods, and the optimal tradeoff over the entire studied time horizon is the focus of this model. The application of the proposed model is also presented in this paper, and the computational result and analysis illustrate a deep insight of this model.

6. Exergy analysis of CO₂ heat pump systems

A. Papadaki, A. Stegou-Sagia

School of Mechanical Engineering, Department of Thermal Engineering, National Technical University of Athens, 9 Iroon Polytechniou Str., Zografou 15780, Athens, Greece.

Abstract: Carbon dioxide (CO₂, R744), a natural refrigerant of beneficial properties found everywhere in our ambiance, can provide answer to the environmental problems caused by other refrigerants’ use. The intention of this work is to outline the variation of exergy efficiency factor, COP and exergy flow related to the use of CO₂ in two stage and single stage heat pumps. The relevant mathematical models to the thermodynamic cycles were developed and an attempt was made for our efficiency and exergy losses results to be displayed. Moreover, fundamental process and system design issues of the applicable CO₂ heat pumps cycles were inaugurated, along with their properties and characteristics, comparing CO₂ use to that of R22 and its substitutes R407C and R410A applied in relevant conditions. Since exergy analysis is important theoretical basis for optimizing the systems operation and minimizing the losses, the results of this paper will advance the systems’ design and performance.

7. CO₂ emission optimization for a blast furnace considering plastic injection

Xiong Liu^1,2,3, Xiaoyong Qin^1,2,3, Lingen Chen^1,2,3, Fengrui Sun^1,2,3

1 Institute of Thermal Science and Power Engineering, Naval University of Engineering, Wuhan 430033, P. R. China.

2 Military Key Laboratory for Naval Ship Power Engineering, Naval University of Engineering, Wuhan 430033, P. R. China.

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

Abstract: An optimization model based on mass balance and energy balance for a blast furnace process is established by using a nonlinear programming method. The model takes the minimum CO₂ emission of a blast furnace as optimization objective function, and takes plastic injection or pulverized coal injection into account. The model includes sixteen optimal design variables, six linear equality constraints, one linear inequality constraint, six nonlinear equality constraints, one nonlinear inequality constraint, and thirteen upper and lower bound constraints of optimal design variables. The optimization results are obtained by using the Sequential Quadratic Programming (SQP) method. Comparative analyses for the effects of plastic injection and pulverized coal injection on the CO₂ emission of a blast furnace are performed.

8. Assessment of air pollution elements concentrations in Baghdad city from periods (May-December) 2010

Ahmed F. Hassoon

Department of Atmospheric Sciences, College of Sciences, Al-Mustansiriyah University, Baghdad, Iraq.

Abstract: Air pollution in developing countries has recently become a serious environmental problem, which needs more active air quality monitoring and analyses. To assess air quality characteristics over the city of Baghdad. temporal variations in CO, NO, NO₂, NOX, O₃, SO₂ and PM10 Concentrations measured between May-December 2010 (245 days), at period from 8:00-16:00 daily hour from location called AL-Jadriyah station (44.1E -33.3N, 38.5m above sea level). From diurnal variability of these concentration, we see high daily values of CO and CH₄ 3.25, 1.9 PPM at November while NOX record 0.23 PPM at December that consider as highest daily value. While other pollutant concentration don’t have large variation have 0.14-0.18 PPM. Particular matter at 10um (PM10) have 1.6g/m3 at 21/7/2010. At winter season and specifically at December month, there is good relation between the hourly concentration of PM10 and other chemical pollutant concentration such as CO,SO₂, NO, NOX this can be putting by correlation coefficient r =0.7-0.5. The monthly mean concentration of pollutant CO, NOX, CH₄, NO, NO₂ recorded high value at August Month. While O₃ have large mean concentration in November, while PM10 have large monthly mean concentration at June and July months where there is most frequent dust-storm events. High concentration and its frequency distribution shifts towards large values concentrated at summer seasons June, July, Aug. about 0.25-1.25 PPM and have frequency percent about 82.6%. In winter the frequency distribution shifts towards large values of O₃ even above 61.2% in range 0.085-0.105 PPM. Regarding the frequency distribution of SO₂ all season where shifts towards lower except spring (May) 88.2% at range concentration 0.025-0.125 PPM. Nitrate oxide have different concentration an frequency at several season but NOX have large frequency at summer, other pollutant concentration CH₄ and PM10 have high concentration frequency at this period.

9. Process simulation and maximization of energy output in chemical-looping combustion using ASPEN plus

Xiao Zhang, Subhodeep Banerjee, Ling Zhou, Ramesh Agarwal

Department of Mechanical Engineering & Materials Science, Washington University in St. Louis, 1 Brookings Drive, St. Louis, MO 63130, USA.

Abstract: Chemical-looping combustion (CLC) is currently considered as a leading technology for reducing the economic cost of CO2 capture. In this paper, several process simulations of chemical-looping combustion are conducted using the ASPEN Plus software. The entire CLC process from the beginning of coal gasification to the reduction and oxidation of the oxygen carrier is modeled and validated against experimental data. The energy balance of each major component of the CLC process, e.g., the fuel and air reactors and air/flue gas heat exchangers is examined. Different air flow rates and oxygen carrier feeding rates are used in the simulations to obtain the optimum ratio of coal, air, and oxygen carrier that produces the maximum power. Two scaled-up simulations are also conducted to investigate the influence of increase in coal feeding on power generation. It is demonstrated that the optimum ratio of coal, air supply, and oxygen carrier for maximum power generation remains valid for scaled-up cases with substantially larger coal feeding rates; the maximum power generation scales up linearly by using the process simulation models in ASPEN Plus. The energy output from four different types of coals is compared, and the optimum ratio of coal, air supply and oxygen carrier for maximum power generation for each type of coal is determined.