Cover

Aims and Scope
Editorial Board

1. A parametric study of the natural vibration and mode shapes of PEM fuel cell stacks

Maher A.R. Sadiq Al-Baghdadi

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

Abstract: A PEM fuel cell stack is laminated with a number of plate-type cells, and the latest model is assembled by compression from both ends of plates. PEM fuel cells are exposed to high magnitude vibrations, shocks, and cyclic loads in many applications. Vibrations during operation show significant impact in the longer run of the fuel cells. Frequencies which are not close to the resonant frequencies or natural frequencies show very little effect on the overall performance. However, if the frequency ranges of operation approaches the resonant frequency range, the probability of component failure increases. It is possible that there will be lateral transition of cells or leakage of fuel gas and coolant water. Therefore, it is necessary to evaluate the effects vibration has on the fuel cell. This work aims to understand the vibration characteristics of a PEM fuel cell stack and to evaluate their seismic resistance under a vibration environment. Natural frequencies and mode shapes of the PEM fuel cell stack are modelling using finite element methods (FEM). A parametric study is conducted to investigate how the natural frequency varies as a function of thickness, Young’s modulus, and density for each component layer. In addition, this work provides insight into how the natural frequencies of the PEM fuel cell stack should be tuned to avoid high amplitude vibrations by modifying the material and geometric properties of individual components. The mode shapes of the PEM fuel cell stack provide insight into the maximum displacement exhibited under vibration conditions that should be considered for transportation and stationary applications.

Volume 7, Issue 1, 2016, pp.1-22.

2. Experimental and theoretical investigation of the effect of rotating circular cylinder speed on the lift and drag forces

Ghassan F. Smaisim^1,2, Oula M.H. Fatla^1,3, Agustin Valera-Medina¹, A.M. Rageb4, N. Syred¹

1 School of Engineering, Cardiff University, Cardiff, United Kingdom.

2 College of Engineering, Kufa University, Iraq.

3 College of Engineering, Al-Qadisya University, Iraq.

4 College of Engineering, Basrah University, Iraq.

Abstract: Flow past a circular cylinder is a problem for understanding flow around bluff bodies. This flow has been studied both experimentally and numerically of laminar infinite flow of viscous incompressible fluid around a rotating circular cylinder at Reynolds number 80,120,160 and dimensionless rotation rate, α , (ratio of cylinder surface speed to the free stream velocity) varying from 0 to 6 has been carried out. Navier–Stokes and continuity equations were solved numerically by using finite volume technique is conducted with ANSYS CFX 15 package program. High Speed Photography and LDV, present new experimental results for correlation purposes, captured the flow profile. Rotation can be used as a drag reduction technique. Comparison with previous studies showed good agreement.

3. CFD model using for natural ventilation study in the local building of hot-humid climate in Vientiane Capital, Lao PDR

Pakasith Phonekeo¹, P. Amparo López-Jiménez², Ignacio Guillén Guillamón¹

1 Applied Physics Department. Universitat Politécnica de Valencia. Spain.

2 Hydraulic and Environmental Engineering Department. Universitat Politécnica de Valencia. Camino de Vera s.n. 46022. Valencia, Spain.

Abstract: In Laos, the research of the relationship between local climate and the building is still less, therefore the attentiveness of passive design in building is also rare and depreciates. This study will be some basic guideline for studying about air movement that impact to the building in Laos which has the hot-humid weather all year. This study analyzes how the physical characteristics of air flow affect to the local accommodation building in Vientiane Capital of Laos by using Computational Fluid Dynamics (CFD) techniques. Furthermore, the study aims to investigate the air movement appearance inside the room influenced by the environment around building, particularly the main factors of human comfort including the air movement, the age of air, temperature and pressure.

4. Renovation of NZCB in a poor solar irradiation zone: An investigative case study of residential buildings in Chongqing urban areas

Md Sahadat Hossain^1,2, Baizhan Li^2,3

1 Department of Thematic Studies-Environmental Change, Linköping University, Se-581 83, Linköping, Sweden.

2 Faculty of Urban Construction and Environmental Engineering, Chongqing University, Chongqing, 400045, China.

3 Key Lab of the Three Gorges Reservoir Region’s Eco-Environment, Chongqing University, Ministry of Education, Chongqing, 400045, China.

Abstract: The energy requirements of Chongqing, a major economic hub of Southwest China, have increased annually with at an average of 10.49% per annum since 1997. The predominant primary source of energy is coal. China’s long range goal is for a green economy and solar energy is considered a prime renewable energy source. This investigation assessed the feasibility of solar energy utilization in existing residential buildings in Chongqing Urban Areas. The main objectives of the research were to see “available solar renewable energy resource for utilization” and “how much CO₂ emission could be abated by using solar energy from these residential buildings”. On the basis of average 3.47 kWhm-2d-1 and per capita 20.46m2 residential areas in 2012, the feasibility study found the availability of 1250 kWhm-²d-1 irradiation. In addition, 15% yielding from this availability had the potential of 2.88 MWh annual clean energy generations abating 89.6% of CO₂ emissions from current electricity consumption. The investigative case study in three residential buildings of the Shapingba district of Chongqing found the 0.089, 0.086 and 0.126 tce of CO₂ emissions for per capita 187.89 kWh, 182.23 kWh and 265.37 kWh monthly energy demand. Although the long cash pay back periods (46, 43 and 31 years) don’t suggest immediate strong PV utilization in this area this form of renewable energy in Chongqing could form a distinctive substitute as a flanking measure for zero carbon residential buildings.

5. Exergy analysis for combined regenerative Brayton and inverse Brayton cycles with regeneration after the inverse cycle

Zelong Zhang^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.

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

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

Abstract: Exergy analysis and optimization is carried out for combined regenerative Brayton and inverse Brayton cycles with regenerator after the inverse cycle. The analytical formulae of exergy efficiency of the combined cycle and exergy losses of each component are derived. The largest exergy loss location is determined. It is shown that exergy efficiency increases with the increase in the effectiveness of regenerator in the critical range of the compressor pressure ratio of the bottom cycle. Furthermore, the exergy loss of combustion chamber is the largest in the combined cycle.

6. Distributed energy resources systems towards carbon-neutral urban development: A review and application

Aumand Phdungsilp, Ivo Martinac

Division of Building Service and Energy Systems, KTH Royal Institute of Technology, Stockholm, Sweden.

Abstract: A new trend in energy systems planning through distributed energy systems has attracted increasing research attention worldwide. Through a comprehensive literature review, this paper presents the latest research and development in the field of distributed energy resource (DER) systems. The review identified five key areas of practice: Relevant concept, supply technology, modeling study, energy systems design, and policy assessment. DER systems offer a wide range of benefits and are linked to sustainable built environments. The paper discusses the applicability of the DER systems in the local energy system of a case study in Stockholm, Sweden. The paper describes a plan and system configurations involved in the search for energy supply options to achieve urban carbon-neutrality in the case study.

7. The role of local renewable energy sources in regional energy production: The case of South-East Finland

M. Laihanen, A. Karhunen, T. Ranta

Lappeenranta University of Technology - LUT Energy, P.O. Box 20, FI-53851 Lappeenranta, Finland.

Abstract: The focus of the paper was on discussing the challenges and possibilities of promoting and utilising various renewable energy sources at the regional level. National obligations and the rising prices of fossil fuels have put pressure on energy producers and end users to start utilising renewable energy sources. South-East Finland has one of Europe’s highest forest industry concentrations, and renewable energy sources such as wood fuels are utilised widely. The study utilises earlier regional studies and statistics as well as new results from this study. These results are combined into regional potentials which are presented by regional energy balance. The analyses provide important background information for decision making. The various regions of Finland have different operational environments and local participants need motivation and activation regarding these local possibilities.