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Aims and Scope
Editorial Board

1. CFD model of thermal and velocity conditions in a particular indoor environment

Miguel Mora Pérez¹, Gonzalo López Patiño¹, Ignacio Guillén Guillamón², P. Amparo López Jiménez¹

1 Hydraulic and Environmental Engineering Department. Universitat Politècnica de Valencia. Spain.

2 Applies Physics Department. Universitat Politècnica de Valencia. Spain.

Abstract: The demand for maintaining high indoor environmental quality (IEQ) with the minimum energy consumption is rapidly increasing. In the recent years, several studies have been completed to investigate the impact of indoor environment factors on human comfort, health and energy efficiency. Therefore, the design of the thermal environment in any sort of room, specially offices, has huge economic consequences. In this paper, a particular analysis on the air temperature in a multi-task room environment is modeled, in order to represent the velocities and temperatures inside the room by using Computational Fluid Dynamics (CFD) techniques. This model will help to designers to analyze the thermal comfort regions inside the studied air volume and to visualize the whole temperatures inside the room, determining the effect of the fresh external incoming air in the internal air temperature.

Volume 4, Issue 6, 2013, pp.903-910.

2. Computational fluid dynamics modeling of mixed convection flows in buildings enclosures

Alexander Kayne, Ramesh K. Agarwal

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

Abstract: In recent years Computational Fluid Dynamics (CFD) simulations are increasingly used to model the air circulation and temperature environment inside the rooms of residential and office buildings to gain insight into the relative energy consumptions of various HVAC systems for cooling/heating for climate control and thermal comfort. This requires accurate simulation of turbulent flow and heat transfer for various types of ventilation systems using the Reynolds-Averaged Navier-Stokes (RANS) equations of fluid dynamics. Large Eddy Simulation (LES) or Direct Numerical Simulation (DNS) of Navier-Stokes equations is computationally intensive and expensive for simulations of this kind. As a result, vast majority of CFD simulations employ RANS equations in conjunction with a turbulence model. In order to assess the modeling requirements (mesh, numerical algorithm, turbulence model etc.) for accurate simulations, it is critical to validate the calculations against the experimental data. For this purpose, we use three well known benchmark validation cases, one for natural convection in 2D closed vertical cavity, second for forced convection in a 2D rectangular cavity and the third for mixed convection in a 2D square cavity. The simulations are performed on a number of meshes of different density using a number of turbulence models. It is found that k-epsilon two-equation turbulence model with a second-order algorithm on a reasonable mesh gives the best results. This information is then used to determine the modeling requirements (mesh, numerical algorithm, turbulence model etc.) for flows in 3D enclosures with different ventilation systems. In particular two cases are considered for which the experimental data is available. These cases are (1) air flow and heat transfer in a naturally ventilated room and (2) airflow and temperature distribution in an atrium. Good agreement with the experimental data and computations of other investigators is obtained.

3. Numerical simulation for regional ozone concentrations: A case study by weather research and forecasting/chemistry (WRF/Chem) model

Khandakar Md Habib Al Razi, Moritomi Hiroshi

Environmental and Renewable Energy System, Graduate School of Engineering, Gifu University, 1-1 Yanagido, Gifu City, 501-1193, Japan.

Abstract: The objective of this research is to better understand and predict the atmospheric concentration distribution of ozone and its precursor (in particular, within the Planetary Boundary Layer (Within 110 km to 12 km) over Kasaki City and the Greater Tokyo Area using fully coupled online WRF/Chem (Weather Research and Forecasting/Chemistry) model. In this research, a serious and continuous high ozone episode in the Greater Tokyo Area (GTA) during the summer of 14–18 August 2010 was investigated using the observation data. We analyzed the ozone and other trace gas concentrations, as well as the corresponding weather conditions in this high ozone episode by WRF/Chem model. The simulation results revealed that the analyzed episode was mainly caused by the impact of accumulation of pollution rich in ozone over the Greater Tokyo Area. WRF/Chem has shown relatively good performance in modeling of this continuous high ozone episode, the simulated and the observed concentrations of ozone, NOx and NO₂ are basically in agreement at Kawasaki City, with best correlation coefficients of 0.87, 0.70 and 0.72 respectively. Moreover, the simulations of WRF/Chem with WRF preprocessing software (WPS) show a better agreement with meteorological observations such as surface winds and temperature profiles in the ground level of this area. As a result the surface ozone simulation performances have been enhanced in terms of the peak ozone and spatial patterns, whereas WRF/Chem has been succeeded to generate meteorological fields as well as ozone, NOx, NO₂ and NO.

4. Modeling impact of environmental factors on photovoltaic array performance

Jie Yang, Yize Sun, Yang Xu

College of Mechanical Engineering, Donghua University NO.2999, North Renmin Road, Shanghai, China.

Abstract: It is represented in this paper that a methodology to model and quantify the impact of the three environmental factors, the ambient temperature, the incident irradiance and the wind speed, upon the performance of photovoltaic array operating under outdoor conditions. First, A simple correlation correlating operating temperature with the three environmental variables is validated for a range of wind speed studied, 2-8, and for irradiance values between 200 and 1000. Root mean square error (RMSE) between modeled operating temperature and measured values is 1.19% and the mean bias error (MBE) is -0.09%. The environmental factors studied influence I-V curves, P-V curves, and maximum-power outputs of photovoltaic array. The cell-to-module-to-array mathematical model for photovoltaic panels is established in this paper and the method defined as segmented iteration is adopted to solve the I-V curve expression to relate model I-V curves. The model I-V curves and P-V curves are concluded to coincide well with measured data points. The RMSE between numerically calculated maximum-power outputs and experimentally measured ones is 0.2307%, while the MBE is 0.0183%. In addition, a multivariable non-linear regression equation is proposed to eliminate the difference between numerically calculated values and measured ones of maximum power outputs over the range of high ambient temperature and irradiance at noon and in the early afternoon. In conclusion, the proposed method is reasonably simple and accurate.

5. Fuel gas and char from pyrolysis of waste paper in a microwave plasma reactor

Parin Khongkrapan, Patipat Thanompongchart, Nakorn Tippayawong, Tanongkiat Kiatsiriroat

Department of Mechanical Engineering, Faculty of Engineering, Chiang Mai University, Chiang Mai 50200, Thailand.

Abstract: In this study, a microwave plasma reactor was used for pyrolysis of waste papers. The effects of different argon flow rates on char and gas generation were investigated. Changes in carbon and oxygen contents from those in paper to char were significant. Char yield of over 25 % was obtained with the heating value of about 38 MJ/kg. Average gas yield and total content of combustible fraction (CO, CH₄ and H₂) in the gas product were 2.56 m³/kg and 36 %, respectively. The heating value of gas product and carbon conversion efficiency of the process were maximum at 6.0 MJ/m³ and 73 %, respectively.

6. A review of net metering mechanism for electricity renewable energy sources

Andreas Poullikkas, George Kourtis, Ioannis Hadjipaschalis

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

Abstract: In this work, an overview of the net metering mechanism for renewable energy sources for power generation (RES-E) systems is carried out. In particular, the net metering concept is examined with its benefits and misconceptions. Furthermore, a survey of the current operational net metering schemes in different countries in the world, such as, in Europe, USA, Canada, Thailand and Australia, is carried out. The survey indicated that there are different net metering mechanisms depending on the particularities of each country (or state in the case of USA). Especially, in Europe, only five countries are using net metering in a very simple form, such as, any amount of energy produced by the eligible RES-E technology is compensated from the energy consumed by the RES-E producer, which results to either a less overall electricity bill or to an exception in payment energy taxes. In the USA and the USA territories, any customer’s net excess generation is credited to the customer’s next electricity bill for a 12-month billing cycle at various rates or via a combination between rates. The actual type of net excess generation (NEG) credit is decided by a number of set criteria, such as the type of RES-E technology, the RES-E capacity limit, the type of customer and the type of utility. Regarding any excess credit at the end of the 12-month billing cycle, this is either granted to the utilities, or carries over indefinitely to the customer’s next electricity bill, or is reconciled annually at any rate, or provides an option to the customer to choose between the last two options.

7. Importance of thermal comfort for library building in Kuching, Sarawak

S.H. Ibrahim, A. Baharun, M.D. Abdul Mannan, D.A. Abang Adenan

Department of Civil Engineering, Faculty of Engineering, University Malaysia Sarawak (UNIMAS), 94300 Kota Samarahan, Sarawak, Malaysia.

Abstract: Malaysian Government takes an initiative to provide library in housing areas to improve the quality of human capital. However, the government has to evaluate every aspect of their provision to ensure the services provided meet the demands of the users, including the aspect of thermal comfort in the building. For this study, a library constructed using Industrialised Building System (IBS) are selected for thermal comfort evaluation. The data were analyzed using Corrected Effective Temperature (CET) index. From the data analysis, it shows that thermal comfort in the library could not be achieved most of the time unless when the mechanical cooling is used. A series of technical design improvements are then recommended to improve the thermal comfort inside the library by incorporating construction details without increasing the cost.

8. Maximum power analysis of photovoltaic module in Ramadi city

Majid Shahatha Salim¹, Jassim Mohammed Najim¹, Salih Mohammed Salih²

1 College of Science, University of Anbar, Iraq.

2 Renewable Energy Research Center, University of Anbar, Iraq.

Abstract: Performance of photovoltaic (PV) module is greatly dependent on the solar irradiance, operating temperature, and shading. Solar irradiance can have a significant impact on power output of PV module and energy yield. In this paper, a maximum PV power which can be obtain in Ramadi city (100km west of Baghdad) is practically analyzed. The analysis is based on real irradiance values obtained as the first time by using Soly2 sun tracker device. Proper and adequate information on solar radiation and its components at a given location is very essential in the design of solar energy systems. The solar irradiance data in Ramadi city were analyzed based on the first three months of 2013. The solar irradiance data are measured on earth's surface in the campus area of Anbar University. Actual average data readings were taken from the data logger of sun tracker system, which sets to save the average readings for each two minutes and based on reading in each one second. The data are analyzed from January to the end of March-2013. Maximum daily readings and monthly average readings of solar irradiance have been analyzed to optimize the output of photovoltaic solar modules. The results show that the system sizing of PV can be reduced by 12.5% if a tracking system is used instead of fixed orientation of PV modules.

9. Optimal design of multistage chemostats in series using different microbial growth kinetics

Muhammad Qasim

Petroleum Engineering Technology, Abu Dhabi Polytechnic, U.A.E.

Abstract: In this paper, the optimum design of multistage chemostats (CSTRs) was investigated. The optimal design was based on the minimum overall reactor volume using different volume for each chemostat. The paper investigates three different microbial growth kinetics; Monod kinetics, Contois kinetics and the Logistic equation. The total dimensionless residence time (θTotal) was set as the optimization objective function that was minimized by varying the intermediate dimensionless substrate concentration (αi). The effect of inlet substrate concentration (S0) to the first reactor on the optimized total dimensionless residence time was investigated at a constant conversion of 0.90. In addition, the effect of conversion on the optimized total dimensionless residence time was also investigated at constant inlet substrate concentration (S0). For each case, optimization was done using up to five chemostats in series.

10. Ethernet TCP/IP based building energy management system in a university campus in Saudi Arabia

Ibrahim M Jomoah¹, Sreerama Kumar R², Abdulaziz Uthman M. Al-Abdulaziz³, Nabil Yassien Abdel-Shafi², Ramzy R Obaid³

1 Department of Industrial Engineering, King Abdulaziz University Jeddah-21589, Saudi Arabia.

2 Saudi Electricity Company Chair for DSM and EE, Vice Presidency for Projects, King Abdulaziz University Jeddah 21589, Saudi Arabia.

3 Department of Electrical and Computer Engineering, King Abdulaziz University Jeddah-21589, Saudi Arabia.

Abstract: This paper investigates the effectiveness of the Building Energy Management System (BMS) installed in the typical buildings in the main campus of King Abdulaziz University, Jeddah, in Saudi Arabia. As the domestic electricity and hence the oil consumption in Saudi Arabia is increasing at a very alarming rate compared to the other countries in the world, it is of paramount importance to resort to urgent measures in various industrial, commercial and residential sectors in the country to implement energy conservation measures. The major electrical load in the buildings in the University corresponds to air-handling units and lighting. If the Hajj period, during which millions of pilgrims visit Holy Makah, coincides with the summer, the electricity demand in the country further increases. Considering these issues, the university has taken initiatives to minimize energy consumption in the campuses through the various energy conservation measures. Towards this end, BMS is installed in a few of the typical classrooms and office buildings utilizing the existing campus Ethernet TCP/IP. The data analysis is performed over the period from April to September as it is the peak load period due to summer season. The effectiveness of the BMS in the minimization of the energy consumption in these buildings is established by comparing the results of data analysis with BMS against those before the installation of BMS over the peak period. The investigations reveal that appreciable saving in energy consumption can be achieved with the installation of BMS, the magnitude being dependent upon factors such as building characteristics, type of building, its utilization and period of use.

11. Strategic planning for minimizing CO2 emissions using LP model based on forecasted energy demand by PSO Algorithm and ANN

M. Yousefi¹, M. Omid¹, Sh. Rafiee¹, S.F. Ghaderi²

1 Department of Agricultural Machinery Engineering, University of Tehran, Karaj, Iran.

2 Department of Industrial Engineering, University of Tehran, Tehran, Iran.

Abstract: Iran's primary energy consumption (PEC) was modeled as a linear function of five socioeconomic and meteorological explanatory variables using particle swarm optimization (PSO) and artificial neural networks (ANNs) techniques. Results revealed that ANN outperforms PSO model to predict test data. However, PSO technique is simple and provided us with a closed form expression to forecast PEC. Energy demand was forecasted by PSO and ANN using represented scenario. Finally, adapting about 10% renewable energy revealed that based on the developed linear programming (LP) model under minimum CO₂ emissions, Iran will emit about 2520 million metric tons CO₂ in 2025. The LP model indicated that maximum possible development of hydropower, geothermal and wind energy resources will satisfy the aim of minimization of CO₂ emissions. Therefore, the main strategic policy in order to reduce CO₂ emissions would be exploitation of these resources.

12. Empirical models for predicting wind potential for wind energy applications in rural locations of Nigeria

F. C. Odo^1,2, G. U. Akubue¹, S. U. Offiah¹, P. E. Ugwuoke¹

1 National Centre for Energy Research and Development, University of Nigeria, Nsukka, Nigeria.

2 Department of Physics and Astronomy, University of Nigeria, Nsukka, Nigeria.

Abstract: In this paper, we use the correlation between the average wind speed and ambient temperature to develop models for predicting wind potentials for two Nigerian locations. Assuming that the troposphere is a typical heterogeneous mixture of ideal gases, we find that for the studied locations, wind speed clearly correlates with ambient temperature in a simple polynomial of 3rd degree. The coefficient of determination and root-mean-square error of the models are 0.81; 0.0024 and 0.56; 0.0041, respectively, for Enugu (6.4⁰N; 7.5⁰E) and Owerri (5.5⁰N; 7.0⁰E). These results suggest that the temperature-based model can be used, with acceptable accuracy, in predicting wind potentials needed for preliminary design assessment of wind energy conversion devices for the locations and others with similar meteorological conditions.

13. Sustainable ground transportation – review of technologies, challenges and opportunities

Ramesh K. Agarwal

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

Abstract: Currently there are nearly 750 million ground vehicles in service worldwide. They are responsible for 50% of petroleum (oil) consumption and 60% of all greenhouse gas (GHG) emissions worldwide. The number of vehicles is forecasted to double by 2050. Therefore the environmental issues such as noise, emissions and fuel burn have become important for energy and environmental sustainability. This paper provides an overview of specific energy and environmental issues related to ground transportation. The technologies related to reduction in energy requirements such as reducing the vehicle mass by using the high strength low weight materials and reducing the viscous drag by active flow control and smoothing the operational profile, and reducing the contact friction by special tire materials are discussed along with the portable energy sources for reducing the GHG emissions such as low carbon fuels (biofuels), Lithium-ion batteries with high energy density and stability, and fuel cells. The technological challenges and opportunities for innovations are discussed.

14. Performance evaluation of effluent treatment plant for automobile industry

Farid Ansari¹, Yashwant K. Pandey², P. Kumar³, Priyanka Pandey³

1 Department of Applied Science and Humanities, PDM College of Engineering, Bahadurgarh (Haryana), India.

2 School of Energy & Environmental Studies, Devi Ahilya Vishwavidyalaya, Indore (M.P), India.

3 Department of Environmental Science, Post Graduate College Ghazipur (U.P), India.

Abstract: The automobile industry’s wastewater not only contains high levels of suspended and total solids such as oil, grease, dyestuff, chromium, phosphate in washing products, and coloring, at various stages of manufacturing but also, a significant amount of dissolved organics, resulting in high BOD or COD loads. The study reveals the performance, evaluation and operational aspects of effluent treatment plant and its treatability, rather than the contamination status of the real property. The Results revealed that the treated effluent shows most of the parameters are within permissible limits of Central Pollution Control Board (CPCB), India and based on the site visits, discussion with operation peoples, evaluation of process design, treatment system, existing effluent discharge, results of sample analyzed and found that effluent treatment plant of automobile industry are under performance satisfactory.