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Aims and Scope
Editorial Board

1. Simultaneous hydrogen production and consumption in Anaerobic mixed culture fermentation

Carlos Dinamarca, Rune Bakke

Department of Process, Energy and Environmental Technology, Faculty of Technology, Telemark University College. Kjølnes ring 56, 3918 Porsgrunn, Norway.

Abstract: The aim of the present study is to investigate the relevance of homoacetogenic H₂ consumption on the bio-hydrogen yield and products distribution in mixed culture fermentation. A hybrid anaerobic reactor was operated for 93 days with variable pH and organic loads between 8-16 g glucose/L.d for this purpose. High initial H₂ yield decreased gradually to an equivalent of 0.02-0.4 mol H₂/mol glucose consumed. The distribution of the dissolved organic products was influenced strongly by reactor pH, while the overall H₂ yield was not. Low H₂ yield is attributed mainly to homoacetogenesis at pH > 4.6 and to reduced products formation at pH < 4.6. Simultaneous hydrogen production and consumption occurred and at least 22 % of the produced molecular hydrogen, mainly from butyrate fermentation, was used for the reduction of CO₂ to acetate.

Volume 3, Issue 3, 2012, pp.323-332.

2. Economic feasibility analysis of a wind farm in Caldas da Rainha, Portugal

Wagner Sousa de Oliveira, Antonio Jorge Fernandes

Department of Economics, Management and Industrial Engineering, University of Aveiro & Campus Universitário de Santiago, 3810-193 Aveiro, Portugal.

Abstract: This paper presents the technical and economical feasibility of a wind farm. The method is applied to a potential wind farm site located in Caldas da Rainha, Portugal. The site is considered on technical and economical parameters for the complete plant and its running costs. For technical consideration wind speed, prevailing wind direction, and temperature measurements are performed by using RETScreen Climate Database and Retscreen Product Database. The economic and financial evaluation of the wind farm is made by the software RETScreen^® International Clean Energy Project Analysis and the indicators calculated are WACC, NPV, IRR, SPB, DPB, TLCC, BCR, LCOE, RR and UPAC. The sensitivity analysis backs up the findings through the scenarios developed (Current, S₁, S₂ and S₃).

3. Experimental study on the performance of a prism-shaped integrated collector-storage solar water heater

Ahmad M. Hamood¹, Abdul Jabbar N. Khalifa²

1 Koya University, Faculty of Science and Engineering, Koya, Erbil, Iraq.

2 Nahrain University, College of Engineering, Jadiriya, P.O. Box 64040, Baghdad, Iraq.

Abstract: This paper presents an experimental investigation on the thermal performance of a 500-liter integrated collector storage system in the shape of a prism with a right angle. A grid of 45 thermocouples was assembled inside the storage tank to monitor the temperature distribution, which was utilized to estimate the mass-weighted average temperature inside the tank and the heat gain. The total stored energy for a day in August was found to be 105.92 MJ/m³ with a temperature increase of 25.2˚C. In November, the total stored energy was 65.86 MJ/m³ with a temperature increase of 15.5˚C while it was 56.92 MJ/m³ for January with a temperature increase of 13.6˚C. A comparison between the present experimental results and published theoretical results for a similar shape showed good agreement.

4. Hamilton–Jacobi–Bellman equations and dynamic programming for power-optimization of radiative law multistage heat engine system

Shaojun Xia, Lingen Chen, Fengrui Sun

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

Abstract: A multistage endoreversible Carnot heat engine system operating with a finite thermal capacity high-temperature black photon fluid reservoir and the heat transfer law is investigated in this paper. Optimal control theory is applied to derive the continuous Hamilton-Jacobi-Bellman (HJB) equations, which determine the optimal fluid temperature configurations for maximum power output under the conditions of fixed initial time and fixed initial temperature of the driving fluid. Based on the general optimization results, the analytical solution for the case with pseudo-Newtonian heat transfer law is further obtained. Since there are no analytical solutions for the radiative heat transfer law, the continuous HJB equations are discretized and the dynamic programming (DP) algorithm is adopted to obtain the complete numerical solutions, and the relationships among the maximum power output of the system, the process period and the fluid temperatures are discussed in detail. The optimization results obtained for the radiative heat transfer law are also compared with those obtained for pseudo-Newtonian heat transfer law and stage-by-stage optimization strategy. The obtained results can provide some theoretical guidelines for the optimal designs and operations of solar energy conversion and transfer systems.

5. A greenhouse type solar dryer for small-scale dried food industries: Development and dissemination

Serm Janjai

Solar Energy Research Laboratory, Department of Physics, Faculty of Science, Silpakorn University, Nakhon Pathom 73000, Thailand.

Abstract: In this study, a greenhouse type solar dryer for small-scale dried food industries was developed and disseminated. The dryer consists of a parabolic roof structure covered with polycarbonate sheets on a concrete floor. The system is 8.0m in width, 20.0m in length and 3.5m in height, with a loading capacity about 1,000kg of fruits or vegetables. To ensure continuous drying operation, a 100kW-LPG gas burner was incorporated to supply hot air to the dryer during cloudy or rainy days. Nine 15-W DC fans powered by three 50-W PV modules were used to ventilate the dryer. This dryer was installed for a small-scale food industry at Nakhon Pathom in Thailand to produce osmotically dehydrated tomato. To investigate its performance, the dryer was used to dry 3 batches of osmotically dehydrated tomato. Results obtained from these experiments showed that drying air temperatures in the dryer varied from 35°C to 65°C. In addition, the drying time for these products was 2-3 days shorter than that of the natural sun drying and good quality dried products were obtained. A system of differential equations describing heat and moisture transfers during drying of osmotically dehydrated tomato was also developed. The simulated results agreed well with the experimental data. For dissemination purpose, other two units of this type of dryer were constructed and tested at two locations in Thailand and satisfactory results were obtained.

6. Evaluation of heat pumps usage and energy savings in residential buildings

Nehad Elsawaf¹, Tarek  Abdel-Salam², Leslie Pagliari³

1 Department of Economics, Helwan University, Cairo, Egypt.
2Department of Engineering, East Carolina University, Greenville, NC 27858, USA.
3Department of Technology Systems, East Carolina University, Greenville, NC 27858, USA.

Abstract: The residential housing sector is a major consumer of energy in most countries around the world. In the United States the residential sector consumes about 21 % of the energy and about 35% of the electricity production. Of the total energy consumption per house hold about 33% is consumed for space heating. This study evaluates the energy consumption in residential houses during the heating season. The main objective of the study is to test the effectiveness of using heat pumps for space heating in eastern North Carolina. Data for the current study were collected from four cities in eastern North Carolina. The collected data which includes surveys and actual energy consumption (gas and electrical) were analyzed using statistical methods. Results show that houses with heat pumps as the main source of heating have the lowest energy consumption and the lowest energy intensity (energy per unit area of the house). Houses with electrical furnaces have the highest energy consumption and the highest energy intensity ratios.

7. Optimization of design and operating parameters on the year round performance of a multi-stage evacuated solar desalination system using transient mathematical analysis

P. Vishwanath Kumar¹, Ajay Kumar Kaviti¹, Om Prakash¹, K.S. Reddy²

1 Department of Mechanical Engineering, Sagar Institute of Science and Technology, Gandhinagar, Bhopal, M.P., India.

2 Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai, India.

Abstract: The available fresh water resources on the earth are limited. About 79% of water available on the earth is salty, only one percent is fresh and the rest 20% is brackish. Desalination of brackish or saline water is a good method to obtain fresh water. Conventional desalination systems are energy intensive. Solar desalination is a cost effective method to obtain potable water because of freely available clean and green energy source. In this paper, a transient mathematical model was developed for the multi-stage evacuated solar desalination system to achieve the optimum system configuration for the maximum year round performance and distillate yield. The effect of various design and operating parameters on the thermal characteristics and performance of the system were analyzed. It was found that an optimum configuration of four stages with 100mm gap between them when supplied with a mass flow rate of 55kg/m²/day would result in best performance throughout the year. The maximum and minimum yields of 28.044 kg/m²/day and 13.335 kg/m²/day for fresh water at a distillate efficiency of 50.989% and 24.245% and overall thermal efficiency of 81.171% and 40.362% are found in the months of March and December respectively owing to the climatic conditions. The yield decreases to 18.614 kg/m²/day and 9.791 kg/m²/day for brine solution at a distillate efficiency of 33.844% and 17.802% and overall thermal efficiency of 53.876% and 29.635% for March and December respectively The maximum yield of 53.211 kg/m²/day is found in March at an operating pressure of 0.03 bar. The multi-stage evacuated solar desalination system is economically viable and can meet the needs of rural and urban communities to necessitate 10 to 30 kg per day of fresh water.

8. A study of kinematic vertical motions in the troposphere in Iraq

Hassan H.Salman, Sama K. AL-Dabbagh, Hadil J. AL-Shouhani

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

Abstract: Vertical velocity has been computed kinematically, and divergence has been calculated by finite differences method by using Taylor theory at levels (1000 to 250) HPa for the first day of January and July, 2010. The data used in this study covered Iraq as a grid of twelve points extends from (30 ̊-36 ̊) N latitudes and (40 ̊5'- 46 ̊5') E longitudes with a uniform grid interval of 3 degrees longitude and 3 degrees latitude. O'Brien adjustment technique has been used to correct the computed divergence and vertical velocity. This study showed that, after comparing the results with the synoptic features, in general there is compatibility between the corrected vertical velocity and the synoptic features.

9. Thermal power system analysis using a generalized network flow model

John Arun Kumar¹, Radhakrishna Chebiyam²

1 Former Senior Design Engineer, Power System Analysis and Control Group, Bharat Heavy Electricals Limited, New Delhi, India.

2 Former Director, Academic Staff College, JNT University, Hyderabad-72, India.

Abstract: This paper analyzes an Integrated Thermal Power System using a Multiperiod Generalized Network Flow Model. The thermal system analysis is carried out by taking into account the complex dynamics involved in utilizing multiple energy carriers (coal, diesel and natural gas). The model comprises energy source nodes, energy transformation nodes, energy storage nodes, energy demand nodes and their interconnections. The solution to the integrated energy system problem involves the evaluation of energy flows that meet the electricity demand at minimum total cost, while satisfying system constraints. This is illustrated through the India case study using a minimum time-step of one hour. MATLAB based software was developed for carrying out this study. TOMLAB/CPLEX software was utilized for obtaining the optimal solution. The model and the methodology utilized for conducting the study would be of interest to those involved in integrated energy system planning for a country or a region.

10. Experimental investigation of operating parameters and control the performance of a PEM fuel cell

I. Khazaee¹, M. Ghazikhani²

1 Department of Mechanical Engineering, Torbat-e-jam branch, Islamic Azad University, Torbat-e-jam, Iran.

2 Engineering Faculty, Mechanical Engineering Department, Ferdowsi University of Mashhad, Mashhad, P.O. Box 9177948944-1111, Iran.

Abstract: In this study, the performance of a PEM fuel cell is investigated experimentally. Some parameters such as input oxygen temperature, input hydrogen temperature, cell temperature, input pressure, oxygen flow rate and hydrogen flow rate affect the performance of the cell. A series of experiments are carried out to investigate the influence of the above parameters on the polarization curve under the normal conditions. A PEM fuel cell with 25 cm2 active area and Nafion 117 membrane for the anode and cathode is employed as a membrane electrode assembly. The results show that increase in the operating temperature of the cell and inlet gases and pressure can enhance the cell performance. Also the results show that when the oxygen flow rate is at 0.9 L/min and the hydrogen flow rate is at 0.5 L/min the performance of the cell increases.

11. Experimental evaluation of C.I. engine performance using diesel blended with Jatropha biodiesel

Sunil Kumar¹, Alok Chaube², Shashi Kumar Jain³

1 Mechanical Department, R. G. P. V. Bhopal (M.P.), India.

2 Mechanical Department, Jabalpur Engineering College Jabalpur (M.P.), India.

3 School of Energy and Environment Management, R.G.P.V. Bhopal, India.

Abstract: Costlier and depleting fossil fuels are prompting researchers to use edible as well as non-edible vegetable oils as promising alternative to petro-diesel. The higher viscosity of vegetable oils leads to problem in pumping, atomization and spray characteristics. The improper mixing of vegetable oils with air leads to incomplete combustion. The best way to use vegetable oils as fuel in compression ignition (CI) engines is to convert it into biodiesel. Biodiesel is a methyl or ethyl ester of fatty acids made from vegetable oils (both edible and non-edible) and animal fat. The main feedstock for biodiesel production can be non-edible oil obtained from Jatropha curcas plant. Jatropha curcas plant can be cultivated on different terrains in India under extreme climatic conditions. Biodiesel can be used in its pure form or as a blend with petro-diesel in different proportions. It is being used in CI engines because it has properties similar to petro-diesel. The aim of this paper is to analyze suitability of petro-diesel blended with biodiesel in varying proportions in CI engines. For this purpose, a stationary single-cylinder four-stroke CI engine was tested with diesel blended with Jatropha biodiesel in 0%, 5%, 20%, 50%, 80% and 100%. Comparative measures of specific fuel consumption (SFC), brake thermal efficiency, smoke opacity, HC, CO₂, CO, O₂, NOX have been presented and discussed. Engine performance in terms of comparable brake thermal efficiency and SFC with lower emissions (HC, CO₂, CO) was observed with B20 fuel compared to petro-diesel. Volumetric efficiency showed almost no variation for all the blends. Important observations related to noise and vibrations during testing have also been discussed.