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Über dieses Buch

This multi-disciplinary volume presents information on the state-of-the-art in sustainable energy technologies key to tackling the world’s energy challenges and achieving environmentally benign solutions. Its unique amalgamation of the latest technical information, research findings and examples of successfully applied new developments in the area of sustainable energy will be of keen interest to engineers, students, practitioners, scientists and researchers working with sustainable energy technologies. Problem statements, projections, new concepts, models, experiments, measurements and simulations from not only engineering and science, but disciplines as diverse as ecology, education, economics and information technology are included, in order to create a truly holistic vision of the sustainable energy field. The contributions feature coverage of topics including solar and wind energy, biomass and biofuels, waste-to-energy, renewable fuels, geothermal and hydrogen power, efficiency gains in fossil fuels and energy storage technologies including batteries and fuel cells.

Inhaltsverzeichnis

Frontmatter

1. Comparative Study of Effect of Cloudiness/Haziness Factor on the Quality of Solar Radiation

In this paper, the effect of cloudiness/haziness factor on the quality of solar radiation is analysed. First, the solar radiation is predicted and compared with the experimental observations and then, the exergy of solar radiation is calculated and analysed based on various models. The effect of cloudiness/haziness factor is plotted in the form of graphs. Other factors affecting the solar radiation, namely, atmospheric transmittance, perturbation factor and background diffuse radiation are also discussed briefly. It is found that for lower values of cloudiness/haziness factor, the solar energy is more and vice versa. Also, lower the cloudiness/haziness factor better would be the intensity of solar radiation.

Anand S. Joshi, Ibrahim Dincer, Bale V. Reddy

2. Investigation of a Renewable Energy-Based Integrated System for Baseload Power Generation

A renewable energy-based integrated system is proposed for baseload power generation. Wind, solar, and biomass options are considered. The electric power produced by wind turbines, a photovoltaic (PV) system, and fuel cells is fed to the power grid. The surplus electricity produced by the integrated energy system is stored in forms of compressed air and hydrogen. When required, the compressed air is heated in a combustion process and expanded in a gas turbine for further power generation. The hydrogen produced by the electrolysis process is fed to a solid oxide fuel cell (SOFC) system for electricity generation. The system is analyzed with energy and exergy methods, and results are presented for monthly power generation, compressed air energy storage (CAES) and compression, and hydrogen production and consumption rates. Moreover, exergoeconomic analyses are performed based on the unit exergy cost of the electricity produced by the integrated system. The round-trip efficiency of the CAES system is 60 % without considering heat recovery potentials. The overall energy and exergy efficiencies of the integrated system are 37.0 and 31.9 %, respectively. Results of the exergoeconomic analyses show that the unit cost of electricity generated by the Wind-CAES system is 7 ¢/kWh, while it is 89 and 17 ¢/kWh for the photovoltaic-hydrogen-solid oxide fuel cell and the biomass-solid oxide fuel cell-gas turbine systems, respectively.

Mehdi Hosseini, Ibrahim Dincer, Marc A. Rosen

3. Investigation of Organic Rankine Cycle Performance with Variable Mixture Composition

The present study deals with a comprehensive thermodynamic modeling of a renewable energy-based organic Rankine cycle (ORC). In this regard, two different cases are chosen to investigate the effect of mixture composition on the cycle performance in terms of exergy efficiency. While one cycle responses negatively to the mixture variation, another shows an increase in cycle performance and hence, efficiency. In addition, this study reveals that using a variable mixture composition can provide a wide range of working conditions for design purposes. The effects of working fluid composition on the turbine and pump works and exergy efficiency of the cycle are investigated, and the results are discussed as well. The exergy efficiency drops by about 0.002 in the first case, but increases by about 0.01 in the second case. It appears that temperature ratios can act like indicators of the cycle performance.

H. Barzegaravval, Ibrahim Dincer

4. Comparative Performance Assessment of Two Geothermal-Based Integrated Systems for Hydrogen Production

In this paper, we conduct a comparative performance assessment study between a conventional electrolyzer and a steam methane reformer (SMR) to investigate which one provides a better option from energy, exergy and sustainability perspectives. The power to both systems is provided by a quintuple flash power plant running on a geothermal source. The quintuple flash power plant is selected due to its capability of producing power in an efficient and environmentally-benign manner. The results show that increasing the ambient temperature increases the overall system exergy efficiency of the first system (consisting of an electrolyzer) from 51.7 to 60.8 % while this remains almost constant at 6.8 % for the second system (containing SMR). The amount of hydrogen produced by the electrolyzer and SMR vary varies from 3.9 to 65.3 L/s and 365 to 426.5 L/s, respectively, with a rise in the geothermal source temperature. With increase in the geothermal source temperature, the exergy efficiencies vary from 54.2 to 62.1 % for the first system and 6.6 to 7.6 % for the second system. Furthermore, the first system is much more sustainable compared to the second system.

T.A.H. Ratlamwala, Ibrahim Dincer

5. Exergetic Optimization of Two Renewable Energy Based Tri-generation Systems Using Genetic Algorithm

In the present study, two renewable energy based tri-generation systems are considered. Optimization has been done using genetic algorithm in order to optimize the objective function, which is the maximization of overall exergy efficiency of system. Biomass and solar are the main sources of energy for both systems, respectively. Energy and exergy efficiencies are defined with or without considering tri-generation and the effect of tri-generation over single generation has been analyzed. The optimum value of objective function, which is the exergy efficiency of the system, is found to be equal to 36.18 % for biomass operated system and 70.68 % for solar operated system. Further, a parametric study has been conducted in order to observe the effect of variation in different parameters on the efficiency of the system.

M. Malik, M.Al Ali, Ibrahim Dincer, S. Rahnamayan

6. Performance Evaluation of Integrated Energy Systems

The current literature on integrated energy systems for various applications is discussed and how energy systems are integrated for multigeneration purposes is explained. Three integrated energy systems, including renewable and non-renewable ones, are considered to enhance the analyses. A micro-gas turbine integrated system is selected as the non-renewable system while biomass and ocean thermal energy conversion based energy systems are considered as the renewable options. Exergy analysis is conducted to determine the irreversibilities in each component and the system performance. Furthermore, economic and environmental impact assessments of the systems are conducted, and the results are presented for each integrated system. The results show that the integrated energy systems have higher exergy efficiency compared to single generation unit and that the integration results in reduction of greenhouse gases emission. The performances of the three systems are compared, and the results show that the choice and benefits of integrated systems strongly depends on the priorities of the designers and engineers.

Pouria Ahmadi, Ibrahim Dincer, Marc A. Rosen

7. Performance Assessment of a Two–stage Heat Pump–Drying System

In this study, energy and exergy analyses of a two–stage heat pump–drying system are conducted, and the performance of the overall system is then evaluated. The system has two cycles: a heat pump and a drying cycle. The working fluid of the heat pump and the drying cycles are R-134 A and air, respectively. The two–stage heat pump consists of two evaporators; one operates at high pressures while the other one operates at lower pressures for additional cooling and dehumidification of the drying air. After the condenser, two sub–coolers are used for additional heating. Also, the exergy destruction rates, energy and exergy efficiencies of each unit, cycle, and the overall system are calculated. Each unit and cycle’s exergy destruction rate is investigated to identify the corresponding unit’s relative irreversibility, and as a result, potential points to improve the system’s exergetic performance. Parametric studies are conducted to understand the effect of ambient temperature on exergy efficiencies and exergy destruction rates of each unit, cycle, and the overall system. The selection and design of these to reduce exergy destruction, and as a result, increase the exergy efficiency of the system by minimizing irreversibilities is discussed in this study. Furthermore, the effect of air mass flow rate on system COP is studied. The initial results with 0.5 kg/s air flow rate at ambient temperature and pressure of 5 °C and 1 atm gives energy and exergy efficiencies of 62 % and 35 %, respectively. The COP of the system is calculated to be about 3.8.

Canan Acar, Ibrahim Dincer

8. Comparative Assessment of Nuclear Based Hybrid Sulfur Cycle and High Temperature Steam Electrolysis Systems Using HEEP

Hydrogen is one of the most promising alternatives as a replacement for the fossil fuels, since it can be produced by several methods using numerous sources. Sustainable production of hydrogen is highly dependent on the energy source utilized. Nuclear and renewable energy resources are considered as the best candidates for sustainable hydrogen production. Although there are numerous methods possible for hydrogen production, cost and economic factors play a crucial role in the feasibility and applicability of such plants. In this study, cost assessment of nuclear hydrogen production methods can be comparatively evaluated using Hydrogen Economy Evaluation Programme (HEEP) provided by International Atomic Energy Agency (IAEA). HEEP software is a user friendly cost estimation package, including various nuclear reactor options, as well as hydrogen generation, storage and transportation facilities. Rather than the existing data, HEEP offers user defined options from energy source to end user. Futhermore, hybrid sulfur (HyS) thermochemical cycle and high temperature steam electrolysis (HTSE) hydrogen generation systems are compared using high temperature reactors by considering storage and transportation options. The results show that the cost of hydrogen from HyS is 20 % lower than that of HTSE. HTSE requires more power consumption than HyS cycle, which has the highest impact of plant and production costs.

Hasan Ozcan, Rami Salah El-Emam, Ibrahim Dincer

9. Thermodynamic Analysis of a Cycle Intergrating a Solid-Oxide Fuel Cell and Micro Gas Turbine with Biomass Gasification

An integrated solid-oxide fuel cell-micro gas turbine system with biomass gasification is investigated based on energy and exergy. The system consists of a biomass gasification system, a solid-oxide fuel cell (SOFC), a micro gas turbine (MGT), and a heat recovery steam generator (HRSG). Various parameters are determined for the integrated system, including syngas molar fraction, and heat input to the gasifier. Moreover, exergy flows and exergy destruction rates of major components of the system are calculated. The maximum energy and exergy efficiencies of the gasification system are 65.7 and 84.8 %, respectively. These values for the SOFC-MGT cycle with biomass gasification are reported as 58.3 and 69.6 %. The variations of syngas molar fraction and mass flow rate, gasifier exergy destruction, and CO

2

emissions with the steam to carbon (SC) ratio are investigated. The results show that there is an optimum value for the SC ratio at which the syngas mass flow rates and the gasification energy efficiency reach a maximum. The CO

2

emission, which is an important factor for the sustainability of the system, increases by 19.4 % as the value of the SC ratio increases. Increasing the gasification temperature, from 800 to 1000 °C, reduces the energy and exergy efficiencies of the total integrated system by 7.90 %, mainly by increasing the required heat input to the gasifier.

Mehdi Hosseini, Marc A. Rosen, Ibrahim Dincer

10. Exergy Analysis of Scroll-Based Rankine Cycles with Various Working Fluids

In this study the possibility of converting scroll compressor into expander is investigated. Refrigeration equipment manufacturers produce scroll compressors massively for refrigeration and air conditioning applications. It is shown here that, through appropriate modeling, catalog data of scroll compressors can be used to predict the operation in reverse, as expanders. The modification of the geometry with respect to rolling angle and involute angles are necessary to use scroll compressor as expanders in heat engines. If no modifications are made to the scroll compressor, the efficiency of the Rankine cycle will result low because the built-in volume ratio is not adapted to the cycle configuration for the same pressure and temperature levels in the expanders. A low capacity scroll compressor is selected from a refrigeration equipment manufacturer and using the equations for modeling of positive displacement compressors and the compressor manufacturer data for nominal operation, isentropic efficiency, built-in volume ratio and the flow coefficient of the scroll machine are determined. After these determinations, the expander model has been used to predict the operation of the same scroll machine in reverse as it without and modification of the geometry. The resulting Rankine cycle is non-realizable with a low exergy efficiency of 50 % since the sink temperature for the cycle is far below the normal environmental temperature. In order to run a feasible Rankine cycle with the selected expander, without changing the scroll geometry and the working fluid, the upper pressure and temperature must be increased. It is found that by increasing the pressure and temperature at the expander intake to supercritical value, that is 68 bar and 264 °C, the cycle becomes realizable and achieves an exergy efficiency of 61 %, respectively.

E. Oralli, Ibrahim Dincer

11. Thermochemical Energy Storage Systems: Design, Assessment and Parametric Study of Effects of Charging Temperature

Thermal energy storage (TES) is an advanced technology that can enhance energy systems by reducing environmental impact and increasing efficiency. Thermochemical TES is an emerging method which permits more compactness storage through greater energy storage densities. The design of thermochemical energy storage systems is complex and requires appropriate consideration of many factors. Generally, many criteria need to be evaluated by engineers in engineering design such as cost, environmental impact, safety, reliability, efficiency, size, and maintenance. These factors need to be considered in designing thermochemical TES systems. In this study, some important factors related to design concepts of thermochemical TES systems are considered and preliminary design conditions for them are investigated. Parametric studies are carried out for the thermochemical storage systems to investigate the effects of charging temperature on the efficiency and behavior of thermochemical storage systems. The results show that the charging and overall energy and exergy efficiencies for both closed and open loop systems decrease by increasing the charging temperature.

Ali H. Abedin, Marc A. Rosen

12. Thermodynamic Assessment of Seasonal Stratified Thermal Storage

District energy (DE) and thermal energy storage (TES) are two energy technologies that can enhance the efficiency of energy systems. Also, DE and TES can help address global warming and other environmental problems. In this study, a stratified TES is assessed using exergy analysis, to improve understanding of the thermodynamic performance of the stratified TES, and to identify energy and exergy behavioural trends. The analysis is based on the Friedrichshafen DE system, which incorporates seasonal TES, and which uses solar energy and fossil fuel. The overall energy and exergy efficiencies for the Friedrichshafen TES are found to be 60 and 19 % respectively, when accounting for thermal stratification. It is also found that stratification does not improve the performance of the TES notably. Considering the TES as stratified and fully mixed does not significantly affect the overall performance of the Friedrichshafen TES because, for this particular case, temperatures are very close whether the TES is treated as stratified or fully mixed.

Behnaz Rezaie, Bale V. Reddy, Marc A. Rosen

13. Recent Developments in Solar-Powered Micro CHP Systems

Over the last two decades, the world has exhibited an unprecedented increase in the energy resources demand due to the huge technological and industrial developments accompanied by a tremendous population growth. The fluctuations in the conventional fossil fuel prices and the global warming problem are urging the need for switching towards renewable energy resources. With the buildings and residential sector contributing to a large portion of energy consumption, micro-scale combined heat and power systems (CHP) tend to be an effective solution to satisfy heating and electricity needs for buildings and residential accommodations. Taking advantage of the decentralized production and the capability of being driven by renewable energy resources, micro CHP systems are presented as a feasible substitute to the central production stations especially in rural and developed areas. The current work provides a comprehensive overview for the recent developments in the field of micro CHP systems. Research studies regarding micro CHP systems applications in buildings and residential accommodations are reviewed. Moreover, recent options for micro CHP prime movers are reviewed and compared in terms of the technology development, performance, environmental and economic impacts. Different applications of solar organic Rankine systems in the residential sector are presented including small-scale electricity production and reverse osmosis desalination systems. Discussions are concentrated on micro CHP systems driven by organic Rankine cycle (ORC) which provides more durability and reliability in operation and reduces maintenance levels and safety concerns. In addition, recent studies dealing with solar ORC micro CHP systems are examined. The current work doesn’t only add to the literature on micro CHP systems but also provides recommendations for future design and development of ORC solar-powered micro CHP systems including working fluid selection and solar collector technology used.

Muhyiddine Jradi, Saffa Riffat

14. Evaluation of Transient Behavior of a Single-Effect Absorption Chiller

This paper deals with a lumped-parameter dynamic simulation of a single-effect LiBr–H

2

O absorption chiller. In the majority previous studies, thermodynamic properties of LiBr–H

2

O solution were taken from some approximate relations causing the results to be somewhat inaccurate. These relations were used to solve simultaneous differential equations involving the continuity of species constituting the LiBr–H

2

O solution, momentum equations and energy balances. To diminish the effect of these approximate relations on the results, in this study the thermodynamic properties were taken from the EES software. By making a link between EES and MATLAB softwares, the simultaneous differential equations were solved in MATLAB environment and this process was continued until the convergence criterion was satisfied. Moreover, this paper considers the effect of quality on the concentration of solution at the exits of generator and absorber. This effect was ignored in the previous works. In other words, the concentrations of solution at the generator and absorber were not assumed to be equal with the corresponding concentration at the exit of those components in this paper.

Aghil Iranmanesh, Mozaffar Ali Mehrabian

15. Combined Effect of Global Warming and Buildings Envelope on the Performance of Ground Source Heat Pump Systems

Heating and cooling systems as well as domestic hot water account for over 50 % of the world’s energy consumption. Due to their high thermal performance, ground source heat pump systems (GSHP) have been increasingly used to reduce energy consumption. The thermal performance of GSHP systems strongly depends on the temperature difference between indoor and ground operation temperature. This temperature difference is a function of mean annual air temperature and energy demand for heating and cooling over the year. The thermal load of a building, on the other hand is influenced by the thermal quality of the building envelope (TQBE) and outdoor temperature. Over the time, there is a change in heating and cooling load of buildings due to two reasons; improving the comfort requirements and outdoor temperature change. The overall aim of the current work is to study the impact of climatic changes in combination with TQBE on driving energy of GSHP. This was achieved by comparing the driving energy of the GSHP for different global warming (GW) scenarios and different TQBE. Under climate conditions of selected cities (Stockholm, Roma, and Riyadh), the current study shows that GW reduces the driving energy of GSHPs in cold climates. In contrast, GW increases the driving energy of GSHPs in hot climates. Also it was shown that buildings with poor TQBE are more sensitive to GW. Furthermore, the improvement of TQBE reduces the driving energy more in cold climates than in hot or mild climates.

Mohamad Kharseh, Lobna Altorkmany, Mohammed Al-Khawaja, Ferri Hassani

16. Concentrated Solar Power: A Vision for Rajasthan

Different technologies for solar thermal power plants making use of concentrating solar energy systems are:

Parabolic troughs,

Central receivers (towers) and

Parabolic dishes.

A project of solar trough field combined with a gas fired combined cycle power plant (Integrated Solar Combined Cycle—ISCC) in Rajasthan for the generation 140 MW will have annual abatement of 714,400 t of CO

2

emissions, use of primary fuel (LNG), overcome dust problems, solar energy collected by the solar field during the day will be stored in the storage system and then dispatched after sunset, additional capacity of 100–150 MW can reduce electricity problems, 24 h operation facility and supply of both heat and electricity at least prices. The ISCC will operate as base load plant with and expected plant load factor of 80 %. It will have 35 MW capacity solar thermal block of parabolic trough and 105 MW combined cycle block using natural gas. The ISCC plant will comprise a solar field to support a 35–40 MW solar thermal plants combined cycle power block involving two gas turbines of 70 MW connected to the Heat Recovery Steam Generator (HRSG) and a steam turbine of 70 MW connected to both HRSG. The project will be the first of its kind in the world where solar thermal energy will be integrated into combined cycle power block. This project could easily decrease both electricity charges as well as installation charges of the power plant in India.

Nishant Aggarwal, Dinesh Khanduja

17. Dynamic Exergy Analysis of a Solar Ejector Refrigeration System with Hot Water Storage Tank

A dynamic model is proposed to use in investigating the exergy analysis of a solar ejector refrigeration system using R141, for office air conditioning application for a building in Tehran. Classical hourly outdoor temperature and solar radiation model in a hot summer day were used to provide basic data for analysis. To improve the efficiency of the system a hot water storage tank is used and analyzed dynamically. The results show that dynamic analysis is confidently more useful than analysis in a constant condition. This method is more completed because it can present efficiency of the system components at each time. The components have different efficiencies at different days and hours. Collector has the highest level of irreversibilities and ejector is in the next step. Irreversibilities at the first and the last hours of working-time are higher. In addition, using the hot water storage tank decreased auxiliary heating in the afternoon.

Hooman Golchoobian, Ali Behbahaninia, Majid Amidpour, Omid Pourali

18. Combined Photovoltaic Solar Cell—Fuel Cell System: Powering a Dormitory Building

The feasibility analysis of installing a combined photovoltaic solar cell—fuel cell system for a dormitory building was realized. The idea was to produce energy for day-time consumption via the solar cells, and then using the excess electricity produced via the solar cells for electrolysis so that the hydrogen produced can be utilized in a proton exchange membrane fuel cell in order to provide power for night-time. The annual electricity requirement of the chosen dormitory building was estimated as 50,961.04 kWh, whereas the actual consumption was learned to be 52,037.18 kWh via the electricity bills provided by the dormitory administration. The day and night time electricity requirements of the building were calculated for each month and it was found that the month with the highest energy consumption during the day is December whereas the month with the highest energy consumption during the night is January. The system was designed so that it could meet the day-time energy requirement during December and the night-time energy requirement during January. Such a system was calculated to require a solar cell installation area of 1315 m

2

. The costs of solar cell, electrolyzer and fuel cell systems and any other auxiliary equipment were obtained from various manufacturers’ websites and the total required investment was calculated as $ 887,000. Breakeven periods were calculated in order to have a general idea regarding the feasibility of the combined system. Initially, the breakeven period of this particular combined system was found to be at least 97 years, which is very high. Then, it was considered to sell the excess electricity, that was not consumed either by the building or the electrolyzer, produced during the day-time in the months other than December to the local grid, as allowed by Turkish Law #6094, at a rate of $ 0.13 per kWh. In that case, the breakeven period was found to decrease almost to 19 years, rendering the investment moderately feasible in the long term.

Fehmi Gorkem Uctug, Betul Akyurek

19. Investigation of a Combined Air Source Heat Pump and Solar Thermal Heating System Within a Low Energy Research Home

Over 75 % of the energy consumption of an average UK home can be attributed to space heating and hot water production (Department of Energy and Climate Change 2009). As such, it is important to develop and install efficient low carbon systems, integrated into buildings with high thermal performance, in order to reduce overall energy demand.

To date, testing of Air Source Heat Pump (ASHP) technology in the UK climate has been limited. This study investigates the performance of a combined Panasonic Aquarea 9 KW ASHP and Hoval SolKit® solar thermal collector (STC) within a thermally efficient inhabited research home, in order to assess the ability of the system to deliver heating and hot water requirements.

The testing period extends from 4th July 2011 to 29th February 2012. Initial results indicate that the ASHP and STC combined system is able to deliver the required levels of heating and hot water in order to meet the requirements of the occupants, with reduced bills as compared to traditional heating systems. Indoor temperatures have been maintained at a stable comfortable level, alongside minimal or no reliance on an auxiliary immersion heater for hot water.

An average coefficient of performance (COP) of 3.99 has been calculated for the dataset, exceeding the desired industry target COP of 3 but falling slightly below the manufacturer expected efficiency of 4.1. The COP fell below both values for a significant number of individual days, leading to questions over the consistency of the system efficiency. It should also be noted that the test period coincided with an unseasonable mild winter in the UK.

Whilst a single renewable technology source is unlikely to provide the energy levels required to heat an average UK home throughout an entire year, the combined system installed in the test house performs favourably when compared to conventional non-renewable heating and hot water systems. In the context of previous research, this study does show positive results and demonstrates that an ASHP/STC combined system may be a suitable installation in a UK home.

Jennifer White, Mark Gillott, Rebecca Gough

20. A Solar Water Heater for Subzero Temperature Areas

There is a general consensus that prevailing Energy Crises 2050 will lead towards a serious shortage of fossil fuels in near future. Avoiding Global warming and energy crises are two major challenges to be faced in the coming decade. In this scenario, synthetic refrigerants are well known to create global warming and ozone depletion phenomena. Among natural refrigerants, CO

2

having favourable properties in terms of heat transfer and thermodynamics, has been chosen as refrigerants in this study. This paper presents an optimal design and implementation of CO

2

based solar water heater using evacuated glass tubes for low insulation area like Gilgit-Baltistan. The performance of designed/fabricated system has been measured using Thermosyphon arrangements. Several parameters, i.e. header design, filling pressure and temperature, height of tank, heat exchanger design, pipe size and its material, of this self-sustained energy free system have been thoroughly studied. Further, they have been optimized for the best performance.

Naeem Abas, Nasrullah Khan, Ishtiaq Hussain

21. Modeling of the Heliostat Field in Central Receiver Systems for A Given Input Power

The aim of this paper is to model the heliostat field in central receiver solar power plant (CRSPP) for a given input power. An in-house computer program is developed based on the vector geometry to select an individual heliostat and calculate its characteristic angles at any time of the day, any day of the year and any location on earth. This program is also used for open loop control of the heliostat field. To find the layout of heliostat field, the radial staggered configuration is used for the heliostat field as one of the best configurations used so far. Then, the locations of heliostats are determined and the efficiency of each heliostat is calculated in order to find the most efficient heliostats in the field. The heliostats with higher efficiency (more than 80 %) are chosen to be located in the field. Then, by calculating the input power of each heliostat supplied to the receiver, the absorbed heat power by the receiver is calculated. Consequently the minimum number of heliostats with their locations is determined for a specific heat power. The results show that for a 20 MWt (thermal power) CRSPP, 294 heliostats are needed which result in a heliostat layout with 86.45 % total efficiency.

Pouyan Talebizadeh, Mozzafar Ali Mehrabian, Morteza Abdolzadeh, Mohammad Reza Azmi

22. Single Pass Solar Air Heater Without Absorber

The single pass solar air heater is constructed and tested for thermal efficiency at a geographic location of Cyprus in the city of Famagusta. The length and the width of the collector are 150 and 100 cm respectively. The distance between the cover glass, 0.4 cm in thickness, and the bottom of the collector, is 3 cm. The absorber plate was replaced by fourteen steel wire mesh layers, 0.2 × 0.2 cm in cross section opening, and they were fixed in the duct parallel to the glazing. The distance between each set of wire mesh layers is 0.5 cm to reduce the pressure drop. The wire mesh layers were painted with black before installing them into the collector. The obtained results show that as the mass flow rate increases, the efficiency of the system will also increase. The temperature difference (ΔT) between the inlet and outlet air through the system increases as the mass flow rate decreases. The maximum ΔT (45.8 °C) is achieved at the flow rate of 0.011 kg/s. The range of the mass flow rate used in this work is between 0.011 and 0.04 kg/s. It is also found that the maximum efficiency obtained for the single pass air collector is 53.01 % for the mass flow rate of 0.04 kg/s.

Raheleh Nowzari, Loay Aldabbagh

23. An Alternative Energy Concept: A Solar Power Plant with a Short Diffuser

This paper elaborates an alternative energy concept involving a solar power plant with a short diffuser. The main physical part of the proposed alternative energy source is a gravitational vortex (convective vortices) that can be thought of as a heat engine. A solar power plant with a short diffuser could produce electricity without carbon dioxide emissions by transforming the available solar energy into useful mechanical shaft work. The proposed concept is similar to the solar chimney power plant concept, but without a chimney of limited height; in that sense, the design is closer to the atmospheric vortex engine concept. Specific details about the proposed alternative solution, previous research outcomes and planned future research work will be discussed in this paper.

Sandro Nizetic, Neven Ninic

24. Production of Renewable Hydrogen by Aqueous-Phase Reforming of Glycerol Over Ni-Cu Catalysts Derived from Hydrotalcite Precursors

Ni-Cu catalysts derived from hydrotalcite-like compounds were prepared and evaluated in aqueous-phase reforming of glycerol. The catalysts were characterized by chemical composition, textural analysis, crystalline structure and reducibility. The reaction was carried out in a batch reactor with solution of 10 wt. % glycerol, at 250 and 270 °C. A maximum glycerol conversion of 60 % was achieved at 270 °C. In the gas phase, the H

2

selectivity was always higher than 80 % and formation of CO was very low (< 3 %) at 250 °C. The addition of Cu decreased the formation of methane. H

2

is consumed during the reaction at 270 °C, mainly for Cu-containing catalysts, with simultaneous formation of propylene glycol in the liquid phase. Acetol, lactic acid and acetaldehyde were also formed in the liquid phase, at both temperatures.

Pablo Tuza, Robinson L. Manfro, Nielson F. P. Ribeiro, Mariana M.V.M. Souza

25. Effects of Pyrolysis Conditions on Structural Ingredients and Functional Groups of Hybrid Poplar

In this study, thermal behavior and the functional group distributions of structural ingredients of biomass were investigated under pyrolytic conditions. An energy-forestry tree (hybrid poplar) was used as biomass material. Macromolecular ingredients in this biomass such as holocellulose (hemicellulosics + celluloses) and lignin were isolated chemically using several analytical techniques. Thermal analysis, X-ray Diffraction (XRD), X-ray Fluorescence (XRF), BET surface area, Fourier Transform Infrared Spectroscopy (FTIR), and Scanning Electron Microscopy (SEM) techniques were applied to specify the biomass and its ingredients.

Pyrolysis of biomass was carried out in a horizontal tube furnace from ambient to 600 °C with a heating rate of 10 °C/min under nitrogen flow of 100 mL/min. In this way, biochars were produced at different temperatures, and the effects of pyrolytic conditions on the structural ingredients and the distribution of the functional groups were interpreted.

It was found out that the physical and chemical analysis results as well as the thermal decomposition characteristics of holocellulose, lignin, and extracted biomass are highly different from those of the main biomass sample. In addition, the obtained biochars contain large amounts of aromatic and ether type structures. Also, it was also determined that the aromatic bands get stronger with increasing pyrolysis temperature. Besides, carbonyl bands disappeared as temperature increases. It was also revealed that the lignin contains many functional groups, of which methoxyl groups were the most apparent functionalities. On the other hand, the calorific value of the produced biochars tended to increase with increasing pyrolysis temperature.

Hanzade Haykiri-Acma, Serdar Yaman

26. Contribution for Solar Mapping in Algeria

In the present paper, a solar mapping methodology is presented. The work was carried out for the major part of Algeria; a sample of data covering 50 sites over the whole country was considered. However, due to the lack of radiometric data that are essential for this study, data obtained from simulation were used. Kriging method was chosen in order to perform different interpolations trough Surfer ® software, it will allow us to prepare the Grid file necessary to get to the last step, which is the establishment of solar map for the whole Algerian country.

Abdeladim Kamel, Hadj Arab Amar, Chouder Aissa, Cherfa Farida, Bouchakour salim, Kerkouche Karim

27. Experimental and Theoretical Investigations of Performance of Psychometric Humidification and Dehumidification Solar Water Desalination System Coupled with an Evacuated Tube Solar Collector

There is an acute scarcity of potable water in many parts of the world, and especially in the Middle East region. Important advances have been made in solar desalination technology but their wide application is restricted by relatively high capital and running costs. Until recently, solar concentrator collectors have usually been employed to distill water in compact desalination systems. Currently, it is possible to replace these collectors by the more efficient evacuated tube collectors, which are now widely available on the market at a similar price.

This paper describes the results of experimental and theoretical investigations of the operation of a novel small scale solar water desalination technology using the psychometric humidification and dehumidification process coupled with a heat pipe evacuated tube solar collector with an aperture area of about 1.73 m

2

. A number of experimental tests were carried out using a laboratory rig to investigate its water production capacity. Solar radiation (insolation) during a spring term in the Middle East region was simulated by an array of halogen floodlights. A synthetic brackish water solution was used for the tests and its total dissolved solids (TDS) and electrical conductivity were measured before and after the distillation process.

A mathematical model was developed to describe the system’s operation. A computer program using the Engineering Equation Solver software was written to solve the system of governing equations to perform the theoretical calculations of the humidification and dehumidification processes. The experimental and theoretical values for the total daily distillate output were found to be closely correlated. The test results demonstrate that the system produces about 11.50 kg/m

2

.day of clean water with high desalination efficiency. Following the experimental calibration of the mathematical parameter model, it was demonstrated that the performance of the system could be improved to produce a considerably higher amount of fresh water. A water quality analysis showed that levels were well within the World Health Organization guidelines for drinking water. Further research is being performed to improve the performance of the installation.

Mahmoud Shatat, Saffa Riffat, Yijun Yuan, Abdulkarym Mayere

28. Optimal Siting of Offshore Wind Farms

The goal of this study is finding the best location for constructing an offshore wind farm with respect to investment and operation costs and technical limitations. Wind speed, sea depth and distance between shore and wind farm are three major factors that affect the optimal solution. In other researches in this field, turbine installation technology is considered a fixed parameter. But it shaped 24 % of overnight costs and can bias the project against impossibility. In this study, installation technology is reckoned in three different types related to water depth. At first, a linear relation was assumed between transmission costs, average wind speed and distance from shore. By use of linear regression and value of R-Square, two relations fitness was shown. Then, by considering the sea depth in wind turbine installation technology, investment cost and environmental aspects of wind farm distance from the shore, we designed the basic structure of the model. Finally, we executed the model in Kish island offshore parts and found the right place for constructing a wind farm in order to meet the island electricity demand. Also, it was found that the most important factor in determining the average cost of production is the wind speed and can largely compensate for the additional costs imposed by the selecting an appropriate location.

Salman Kheirabadi Shahvali, Seyed Hadi Nourbakhsh, Hamed Ganjavi Shakouri

29. An Investigation into a Small Wind Turbine Blade Design

A small wind turbine blade was designed to be aerodynamically efficient, economical and easy to be manufactured. Aerodynamic analysis was conducted using commercially available software. The aerodynamic analysis suggested laminar flow airfoils to be the most efficient airfoils for such use. Blade geometry was determined after calculating baseline geometric values to have low weight and drag while yielding maximum torque. The blade span was constrained such that the complete wind turbine can be roof-top mountable. The blade was designed without any taper or twist to comply with the low cost and ease of manufacturing requirements. For low cost and favorable strength to weight ratio, fiberglass-epoxy was used as the blade material. Computer simulated structural test results suggested that skin thickness of 1 mm of fiberglass-epoxy can sustain the loads on the blade. The wind turbine blade produces 3.1 N lift with 6.3 N.m torque at 4 m/s wind speed. Since it uses a relatively inexpensive material, fiberglass-epoxy, the cost of the blade is low. Fiberglass-epoxy is also easy to work with hence it contributes towards manufacturing ease. Overall, the research was successful in designing a wind turbine blade that is easy to be manufactured, economical and has high torque.

Sayem Zafar, Mohamed Gadalla, Seyed M. Hashemi

30. Hydrogen Production by Reforming Clathrate Hydrates Using the in-Liquid Plasma Method

Clathrate hydrates, which were formed from methane and cyclopentane, were decomposed by plasma at atmospheric pressure. Methane hydrate was synthesized by injecting methane into shaved ice in the reactor at a pressure of 7 MPa and a temperature of 0 °C. In addition, cyclopentane hydrate was formed by adding surfactant into cyclopentane-water emulsion at 0.1 MPa and a temperature of 0 °C. The process of plasma decomposition of clathrate hydrates has been carried out by irradiating high frequency plasma at the tip of the electrode in clathrate hydrates. 2.45 GHz MW oven and 27.12 MHz RF irradiation were used. This study results gas production that its content identified by gas chromatograph. High purity of hydrogen would be extracted from clathrate hydrate using the in-liquid plasma method.

Andi Erwin Eka Putra, Shinfuku Nomura, Shinobu Mukasa, Hiromichi Toyota

31. Facilitation of Wind Energy Conversion System Selection as Distributed Generation in Household/Commercial and Agricultural Sectors; Case Study of Iran

Distributed generation is an approach to power generation by low capacity systems. In this paper small wind turbines are investigated as distributed generation systems used to satisfy household/commercial and agricultural sectors demand. This paper explains a decision-making process during which consumers can easily define appropriate Wind Energy Conversion System (WECS), considering economical accordance by the amount of power consumption and climate condition of installation place. Rotor diameter and turbine hub height are distinguished as two main parameters affecting WECS, referring to consumption rate and climate circumstances of the place. Mathematical relation between Cost Per Unit (CPU) of generated power and these two, is determined with high correlation coefficient which will be applied during the process to easily nominate different WECSs. Having the amount of costs paid by a family per 1 kWh of electricity consumption, WECS characteristics can be conveniently specified using this relation. To examine the influence of each of the above parameters and increasing the validity of the results, turbines with different rated powers and hub heights, are used in four regions with various geographical circumstances.

Arash Hatami, Hamed Shakouri Ganjavi

32. An Integrated Monitoring Framework for Geothermal Space-Heating Systems in Residential Buildings, Fort McMurray

Energy saving is a significant factor in heating system design. Geothermal systems are considered as an effective means to save energy and reduce potential environmental footprint through eliminating greenhouse effects. This paper presents a proposed integrated monitoring framework developed to use geothermal heating systems efficiently. The proposed framework includes a systematic approach to understanding geothermal systems, which is tested on a real-life project in Fort McMurray, Alberta, Canada, where heating is the major contributor to energy consumption. This project utilizes a geothermal system as the main heating system. The main challenges in the case study are that (1) a geothermal system in this project is not designed as cooling system to recover heat from buildings in summer and (2) Fort McMurray has extreme dry-cold weather. To overcome these challenges, the proposed geothermal system is combined with solar systems, drain water heat recovery (DWHR) systems, and conventional electric or natural gas energy for space-heating. In addition, a make-up air system is also installed to improve indoor air quality.

This paper first researches geothermal systems in the context of energy saving and then compares typical geothermal system practices with the proposed strategy. The advantages of such an integrated design are intuitively clear after comparing the typical usage of geothermal system and the usage in the proposed integrated system. It is concluded that this strategy can extend the lifetime of a geothermal system, provide significantly more energy, and become more energy efficient. The research results will be validated through monitoring systems, data collection, and thermal energy calculations.

Since this is a multi-disciplinary long-term project with a long period, sensors are used to monitor the integrated heating system performance. The resulting data is analyzed to justify the proposed integrated system through estimating thermal energy generated by each heating system, and evaluating the efficiency of each system. Thermocouple and pressure sensors have been located and systems are still being monitored. However, additional sensors to monitor temperature difference and pipe flow rate are still required. Therefore, this paper suggests a new design of monitoring which incorporates additional sensors. After data collection and calculations are completed, the thermal energy generated by each system and Coefficient of Performance (COP) of the heat pumps are determined. Calculations and equation derivations are specified in this paper. Ultimately, this paper demonstrates the essential future of the proposed system and suggests adjustments for future heating system designs in order to improve energy efficiency.

Xinming Li, Tanzia Sharmin, Hasan Ufuk Gökçe, Mustafa Gul, Mohammed Al-Hussein, David Morrow

33. Characterization of Heat Transport Processes in Geothermal Systems

The Institute of Materials and Mechanics in Civil Engineering has performed a research program supported by the Federal Ministry of Economics and Technology (BMWi) from 2010 till 2012. The main objective of this research program is titled “experimental investigation for the verification of a Finite-Element-Multiphase-Model for heat transport processes in the ground” whereby the subsoil is analyzed as a three-phases-model with separate consideration of conduction, convection and their subsequent interaction.

Extensive experimental field tests as well as laboratory tests were conducted at the Technical University Darmstadt. In addition to the extensive field tests a geothermal laboratory device has been developed. With the help of this device the heat transport processes in different geological and hydrogeological conditions can be simulated. Furthermore, it is possible to determine the increase of the effective thermal conductivity of a line source with rising groundwater flow velocities. The ratio of conductive and convective energy transport to the whole transported energy can be investigated in laboratory. After all the different types of heat transport processes in geothermal systems can be characterized clearly. With the extensive geothermal data of the laboratory tests common numerical programs can be verified and optimized. Therefore, all measured data will be reconsidered by numerical back analysis. Detailed description of the laboratory apparatus and first results of the numerical sensitivity and back analysis will be given in this paper.

Heiko Huber, Ulvi Arslan

34. The Prospects for Geothermal Application in Algeria

Algeria is favorably positioned in terms of geothermal resources for low and medium enthalpy. The northern Algeria is characterized by complex geology and alpine-type volcanism in the Mio-Pliocene-Quaternary, while the South has a structure much simpler and more regular. More than 200 springs are identified on the territory of Algeria with temperatures of 68 °C in the West, 40 °C at the Center, 96 °C in the East and 60 °C in the South. Geothermal reservoirs are relatively interesting and diverse. They occur both north and south and consist of dolomite tlemcians in the west, carbonate formations in the East and Albian sandstones in the Sahara. Today, geothermal resources of Algeria are used in spas, heating greenhouses and irrigation. Others use successful applications made by including geothermal heat buildings (heating and air conditioning), drying fruits and vegetables, aquaculture, desalination of seawater and brackish water algae production blue green (spirulina) in fish farms. Such applications reduce dependence upon fossil resources (oil). They are very reliable and cost-effective and suitable for the sustainable development of the environment.

Benziada Mébrouk

35. Thermal Interactions of Vertical Ground Heat Exchangers for Varying Seasonal Heat Flux

A numerical finite volume method in a two-dimensional meshed domain is used to evaluate the temperature response in the ground surrounding multiple borehole systems. The effect of installing ground heat exchangers and the temperature rise in the ground over a period of five years is considered. A transient periodic heat flux is assumed on the borehole wall reflecting the annual variation of heat storage/removal in the ground. The annual variation of heat flux on the walls of the boreholes for a building in Belleville, IL is considered and bin data are used with a typical heat pump.

Marc A. Rosen, Seama Koohi-Fayegh

36. Environmentally Friendly Systems: Earth Heat Pump System with Vertical Pipes for Heat Extraction for Domestic Heating and Cooling

Geothermal heat pumps (GSHPs), or direct expansion (DX) ground source heat pumps, are highly efficient renewable energy technology, which use the earth, groundwater or surface water as heat sources when operating in heating mode or as heat sink when operating in cooling mode. They are receiving an increasing interest because of their potential to reduce primary energy consumption and thus reduce emissions of the GHGs. The main concept of this technology is that it utilises the lower temperature of the ground, which approximately remains relatively stable throughout the year, to provide space heating, cooling and domestic hot water for buildings. The main goal of this study is to stimulate the uptake of the GSHPs. Recent attempts to stimulate alternative energy sources for heating and cooling of buildings has emphasised the utilisation of the ambient energy from ground source and other renewable energy sources. The purpose of this study, however, is to highlight the fact that use of the GSHPs as an environmental friendly technology able to provide efficient utilisation of energy in the buildings sector in an attempt to promote using of the GSHPs for heating and cooling. The paper presents experimental and theoretical results of the DX GSHPs carried out at the Department of Architecture and Built Environment in the University of Nottingham. The study highlights the potential energy cost saving that could be achieved through the use of ground energy sources. It also focuses on the optimisation and improvement of the operation conditions of the heat cycle and performance of the DX GSHP. It is concluded that the direct expansion of the GSHP, combined with the ground heat exchanger in foundation piles and the seasonal thermal energy storage could play a major role reducing building energy needs.

Saffa Riffat, Siddig Omer, Abdeen Omer

37. Thermal Response Test Analysis for an Energy Pile in Ground-Source Heat Pump Systems

A thermal response test (TRT) analysis for a cylindrical energy pile (CEP) was carried out in order to determine the thermal properties of the materials in different regions of the system being modelled. Sample test data were generated by using a three-dimensional numerical model of the CEP. Various combinations of the materials inside and outside the CEP were investigated. It was found that the thermal properties of both the CEP and the surrounding soil could be determined with sufficient accuracy. This was important as the effective thermal properties of the CEP depended on the design of the CEP which could be very difficult to determine by other means. Another study was made to explore the possibility of assuming a homogeneous material outside the pipes with the adoption of equivalent thermal properties determined from the TRT analysis so that an analytical modeling approach could be employed. A comparison of the simulation results was made for the CEP based on the specified thermal properties of the various regions with those for the case in which the equivalent thermal properties was used. By applying a cooling-dominated annual periodic load profile, it was found that the simulated temperature of the fluid leaving the CEP could differ substantially. This meant that the assumption of a homogeneous material outside the pipes could lead to erroneous results.

Chun Kwong Lee, Hong Nam Lam

38. Thermal Performance Comparison Between Longitudinal and Lateral Hollow Plate Fin Heat Sinks

Micro heat sinks are being widely used in electronics cooling. Perforations in micro heat sinks have proven to give better heat transfer than a solid ones. A numerical investigation is conducted in this study for three-dimensional fluid flow and convective heat transfer from hollow fins with longitudinal and lateral perforation. Incompressible air as working flu id is modeled to calculate the fluid flow parameters. Temperature field inside the fins is obtained by solving Fourier law of heat conduction equation. Flow and heat transfer characteristics are presented for Reynolds numbers from 70 to 234 based on the fin thickness. Numerical simulation is validated with the published experimental results of the previous investigators and good agreement is observed. Results show that the fins with lateral perforations have better heat transfer enhancement and but higher pressure drop.

M. F. Ismail, M.A. Zobaer, M. T. H. Khan

39. Model-Based Analysis of Singapore’s Energy System

Sustainable energy production and usage will become important key factors in future energy systems. In particular, Singapore as one of the world’s most densely populated countries with a high standard of living, needs a long-term concept for its energy use. Besides the high oil consumption of the industrial sector, power generation, which is nearly fully based on gas and oil, causes a high demand of fossil fuels. This leads not only to high CO

2

emissions but also to a significant import dependency on neighboring countries. Renewable energy sources and a more efficient conversion of energy are necessary for sustainable economic growth.

The analysis of Singapore’s energy system is carried out by using the mathematical optimization model TIMES (The Integrated MARKAL (Market Allocation) EFOM (Energy Flow Optimization Model) System). This optimization model acts as an economic model generator for local, national or multi-regional energy systems. After modeling Singapore’s energy system as a network consisting of processes (power plants, electric vehicles etc.) and commodities (energy carriers, passenger kilometers etc.), it is cost-optimized regarding to a defined objective function. Furthermore, various boundary conditions (energy prices, policies etc.) are taken into consideration.

Based on the TIMES calculations, different scenarios for energy generation, conversion and consumption are analyzed and assessed on the basis of primary energy demand, final energy demand and CO

2

emissions. The special focus is on Singapore’s passenger transportation and the integration of different kinds of electric vehicles (battery electric vehicles, fuel cell electric vehicles). In order to show the effects on final energy supply, the existing stock of power plants in Singapore is enhanced by alternative technologies of power generation (solar, coal and nuclear energy).

By this, the necessity of a holistic approach for the development of a sustainable energy system is shown.

Markus Wagner, Karl Schoensteiner, Thomas Hamacher

40. Analysis of a Combined Power and Heating Thermodynamic System Driven by Low Temperature Heat Source

Nowadays, the power shortage becomes more serious. The new methods of producing electricity power have been paid more and more attentions to. All over the world, the low temperature heat source is very abundant, such as the geothermal energy, solar energy and industrial waste heat. In this paper, a combined power and heating thermodynamic system powered by low temperature heat source based on ORC (organic Rankine cycle) was proposed. The system consists of a heat source system, a screw expander, a hot water generator, a condenser and a feed pump. And the fluid R245fa was selected as the working fluid. From the low temperature heat source, firstly the electricity power and secondly the heating power ware gained. The cycle performance of the system was studied at the typical working condition. And some key factors to the system are analyzed. Also, the experiment system was set up, and the experimental performance of the system was studied under the typical working condition. In the period of the experiment, the low temperature heat source is the heat collected from solar. The performance comparison based on the simulation results and the experimental results was done. Also, the actual effects of some factors were analyzed to improve the system.

Jianzhong Song, Xiaosong Zhang, Can Yang, Qikuang Yao

41. A Comparative Life Cycle Assessment of Compressed Natural Gas and Diesel Powered Refuse Collection Vehicles

Consumers and organizations worldwide are searching for low-carbon alternatives to conventional gasoline and diesel vehicles to reduce greenhouse gas (GHG) emissions and their impact on the environment. A comprehensive technique used to estimate overall cost and environmental impact of vehicles is known as life cycle assessment (LCA). In this article, a comparative LCA of diesel and compressed natural gas (CNG) powered heavy duty refuse collection vehicles (RCVs) is conducted. The analysis utilizes real-time operational data obtained from the City of Surrey in British Columbia, Canada. The impact of the two alternative vehicles is assessed from various points in their life. No net gain in energy use is found when a diesel powered RCV is replaced by a CNG powered RCV. However, significant reductions (about 24 % CO

2

-equivalent) in GHG emissions are obtained. Moreover, fuel cost estimations based on 2011 price levels and a 5 year lifetime for both RCVs reveal that considerable cost savings may be achieved by switching to CNG vehicles. Thus, CNG RCVs are not only favorable in terms of reduced climate change impact but also cost effective compared to conventional diesel RCVs, and provide a viable and realistic near-term strategy for cities and municipalities to reduce GHG emissions.

Syed Ahmed, Lars Rose, Mohammed Hussain, Kourosh Malek, Robert Costanzo, Erik Kjeang

42. Anaerobic Treatment and Biogas Production of Raw Leachate from Fresh Market Waste Composting by an Anaerobic Hybrid Reactor

Raw leachate discharged from composting process is considered as a promising feedstock for biogas production with high potential for renewable bioenergy recovery. In order to prevent environmental concerns relating to the composting disposal, anaerobic digestion could be a good practice for treatment and utilizing the wastewater derived from fresh market waste composting facilities. The aim of this study was to examine an anaerobic hybrid reactor performance on organic content reduction and biogas production from the raw leachate. The preliminary study included the examinations on leachate characteristics and biochemical methane potential (BMP) assay. In the pilot study, a 200-liter anaerobic hybrid reactor with a combination of an upflow sludge bed reactor and a filter reactor was set-up and was operated semi-continuously with the raw leachate collected from a fresh market waste composter as feedstock. The prior test results showed that the leachate contains high COD and BOD as 34,500 and 14,775 mg L

−1

, respectively. An extensive data on BMP tests indicated that the leachate could be anaerobically digested and generated biogas with the conversion rate as 0.48 L g

−1

of COD removed of fed leachate. Average methane content in the biogas was approximately 60 %. Similar results were achieved in an observation of the anaerobic hybrid reactor performance for 100 days. The reactor was operated efficiently with hydraulic retention time higher than 10 days and maximum organic loading rate as 8 g COD L–1 day–1. However, H

2

S content in the biogas was higher than 5000 ppm which required further H

2

S clean-up before utilizing biogas as an alternative fuel.

Chinnapong Wangnai, Pratin Kullavanijaya, Somboon Pitayarangsarit

43. A First Experimental Survey on the Urban Heat Island in Padua (Italy)

The Urban Heat Island effect concerns the higher air temperature in urban environment with respect to the rural one. This phenomenon is well known by hundreds of years, but it has been experimentally studied only in the last few decades and in large metropolis. Very different possibilities concerning the measurements are possible (fixed ground based meteorological stations, “transept” measurements, satellite-based infrared sensors), with different difficult and quality of the data measured.

The paper reports on the experimental results obtained by a research group of the University of Padua (Italy) in 2010 and 2011 springs-summers in Padua city. The main thermo-hygrometric variables (dry-bulb temperature, relative humidity, global solar radiation) have been measured along some different paths fixed in advance. The paths have been selected in order to cross different zones of the fabric of the city: urban, sub-urban and rural. The high number of “transepts” implemented in different time bands during the day and after the sunset allows to characterize the phenomenon in different meteorological conditions. The results indicate a presence of the UHI in urban zones of the city up to 5 °C.

This work is intended to be developed during 2012 by the research group of the Department of Management and Engineering of the University of Padua, in cooperation with Co.Ri.La. (Venice) in the European Project “UHI – Development and application of mitigation and adaptation strategies and measures for counteracting the global Urban Heat Islands phenomenon” (3CE292P3). The paper reports the analysis of data recorded by two fixed meteorological stations (in the centre and out of Padua) during the period 1994–2011, that show some increase in the UHI effect during this period. Some guidelines concerning the choice of the experimental measurements settings are supplied by the Authors. The future measurements will be used also to calculate some outdoor comfort index and to verify how the latter will change modifying some characteristic parameters (buildings placement, thermal properties, trees presence, etc.) by a simulation model.

Marco Noro, Renato Lazzarin, Filippo Busato

44. Microwave Enhanced Pyrolysis Of Gumwood

Microwave pyrolysis of biomass has gained increasing interests due to the fact that microwave heating provides a volumetric heating and instant heating at improved heating efficiencies compared with conventional heating techniques. In this study, microwave-enhanced pyrolysis of gumwood was carried out at 500 ℃ with silicon carbide as a microwave absorber. Conventional pyrolysis of gumwood was also studied under the same temperature conditions as that of microwave-enhanced pyrolysis. The yields of pyrolytic products, morphology of bio-char, and composition of bio-oil and bio-gas are analyzed by using Scanning Electron Microscope, Gas Chromatograph/Mass Spectrum and Gas Chromatograph respectively. The yields of pyrolytic bio-oil and bio-gas under microwave heating are 8.52 and 73.26 wt.% respectively, which are higher than the products obtained via conventional methods under similar operating conditions. In microwave-enhanced pyrolysis, numerous carbon nano tubes (CNTs) are formed on the surface of the bio-char. The bio-oil obtained by microwave pyrolysis has simpler constituents compared with conventional pyrolytic bio-oil. The proportions of syngas (H

2

+ CO) and methane (CH

4

) in the gas product produced under microwave-enhanced pyrolysis are 62.52 and 22.41 vol.% respectively, which are higher than that of gas product from conventional pyrolysis. It is clear that microwave-enhanced pyrolysis has shown the potential as an alternative method for biomass conversion.

Shi Kaiqi, Wu Tao, Yan Jiefeng, Zhao Haitao, Hall Philip, Lester Edward

45. Improving Operating Efficiency of Installed Capacity in a Power and Water Cogeneration Plant

Over the years, power and water cogeneration plants have become popular in the gulf region. This is because of the perceived potential for the technology to drastically reduce the unit costs of freshwater and power. While potential benefits of such installations have been realized, additional benefits can be accrued by critically examining the operating performances of installed capacity. In this study, potentials for improving plant operating efficiencies in cogeneration power/water production plants are investigated. Unlike the usual thermodynamics approach, it is shown that by implementing more effective and more efficient methods and techniques in the day-to-day operations of power/water cogeneration plants the potential to reduce the unit costs of water and electricity exist. However, this potential is subject to local and/or regional power and water regulatory market valuations. The approach under taken is to analyze and identify improvements in operating practices that affect; primary fuel utilization, non-fuel variable production costs, and non-fuel operation and maintenance costs. The underlying logic is that by improving plant performances in areas mentioned above, improvements in plant operating efficiencies can be realized. The discussions in this study unfolds by analyzing plant operating efficiencies for improvement options. Relationships between operational practices, their effects and influences on overall plant operating efficiencies are discussed. Estimates of operating efficiency best practice measures in power/water cogeneration plants are used to assess and evaluate the potential for efficiency improvements in power/water cogeneration plants. The results of case study shows that by improving plant operating efficiencies through more effective and more efficient operational practices, production operations can realize significant savings in fuel utilization

Fuel utilization

, reductions in non-fuel variable production costs

Production costs

and reductions in operation and maintenance costs.

Farayi Musharavati

46. Simulation, Modeling and Analysis of Water/Power Ratios for a Dual Purpose Water and Power Production Plant

In dual purpose power and water (DPPW) production plants two challenges are often encountered; (a) maintaining operations that meet a desired water production/demand ratio or power production/demand ratio, and (b) meeting the desired water to power ratio. Although these problems are usually implied in the implemented plant design and technology, operational issues play an important role in fine tuning operations towards optimal performance. In addition, operational practices have a bearing on energy consumption and operating efficiencies. In this study, a simulation based approach is used to provide data for handling the fine tuning of operations towards desired targets. To this end, numerical simulation is used to determine the relationships between total water/power demand and total water/power produced. In order to reduce the specific energy consumption of the plant, investigations on the design and operating features of the DPPW production plants were carried out. An existing DPPW production plant was used as a case study. The investigation proceeded by focusing on identifying the optimal production operation strategies that, if implemented, can reduce energy consumption in the production of water and power. Discrete event simulation was used to experiment with a number of feasible plant configurations and strategies for producing power and water. Water to power ratios were used to compare the effectiveness of the feasible production operation strategies through simulation experiments. For each configuration, average values of the simulated data (i.e. both water and power) were determined and used to calculate water to power ratios. Simulation results show that different plant configurations and different operational strategies and practices affect the water to power ratios. This allows engineers and operators to select plant configurations, operational strategies and practices that give them the desired water to power ratios with respect to demand scenarios. Therefore, simulation is an effective tool in identifying opportunities for tuning operations to meet desired production requirements.

Luma M. Diab, Farayi Musharavati

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