bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical Calculation on Heat Transfer Performance of the Capillary Plane HVAC Terminal System
Authors: Bing Wei , Li Li , Zhang Shuping , Lu Jiang
Published: June 2009

Nowadays as a novel terminal air conditioning system, the capillary plane HVAC terminal system is being researched in China. In this system the terminal capillary pipes are buried in the surface of the ceiling or the wall or the floor with the purpose-built grout, the chilled or heated water circulates in the pipes and exchanges the sensible heat with the indoor air by radiation and convection to make the indoor air parameters stable. The capillary mat terminals usually combine with dedicated outdoor air system and the latter takes on the indoor latent heat. Compared with the floor radiant heating system, the capillary plane HVAC terminal system has the advantages of saving more indoor space and any position installation. In this paper, with the method of numerical calculation the heat transfer performance of the capillary pipe buried in the grout are studied, the average temperature of the radiation surface and average heat flow density in summer and winter are figured out, and the influence factors such as: the pipe spacing, pipe embedded depth, pipe diameter, average temperature of the supply and return water, and design indoor air temperature are analyzed respectively. The optimal mode or trend under given conditions are proposed and the relations of the influence factors are summarized. All these above will be good theoretical references for the design and application of the capillary plane HVAC terminal system.
An Analysis of the Heating in Passive Solar Room With Greenhouse
Authors: Chen Wei , Gao Feng Jia
Published: June 2009

In this paper, heating and heat storage in passive solar heating room with greenhouse has been studied. The unsteady numerical simulation is employed to analyze the performance of the flow and temperature field for the typical sunny day of Wuhan, China, in winter in the heating system. The heat storage layer of passive solar heating room has a great effect on temperature distribution and gas flow in heat storage layer of this system. Properties of the bed worked as solar absorber and storage layer have also been studied.
Designing Environmentally Sustainable Electronic Cooling Systems Using Exergo-Thermo-Volumes
Authors: Shah Amip J. , Patel Chandrakant D.
Published: June 2009

Thermo-volumes allow the design engineer to expediently understand the thermal resistance of a given cooling solution (an indicator of performance) along with its flow resistance (an indicator of the pumping power, or energy consumption, which will be required by the fluid handler). In the present work, we expand upon thermo-volumes by including the lifetime exergy cost (in units of Joules of availability destroyed) as a means to enable the consideration of resource consumption (and thus the environmental sustainability) of the cooling solution. To achieve these exergo-thermo-volumes, we reinterpret previous definitions of thermo-volumes in terms of the entropy generated during heat transfer and fluid flow. The Guoy-Stodola theorem is used to convert this entropy generation into an ‘operational’ exergy loss. Next, based on the material choice and assembly processes used in creating the product, an embedded exergy consumption that accounts for the amount of exergy destroyed during extraction, transportation and disposal of the material is attached to the operational exergy loss. Thus, the total ‘cradle-to-cradle’ exergy loss of the solution is devised. In this framework, the optimal solution will be that which destroys the minimal amount of exergy. Correspondingly, instead of relying upon the COP (which is focused on operational consumption), we propose evaluation of cooling solutions in terms of the heat removal capacity per unit lifetime exergy consumption. The paper concludes by illustrating applicability of the method to the design of an enterprise server. It should be noted that although the paper is focused on electronics cooling solutions, the methodology is designed to be sufficiently general for use in any thermal management application.
Kinetic Investigations of a Two-Step Thermochemical Water-Splitting Cycle Using Mixed Iron Oxides Fixed on Ceramic Substrates
Authors: Neises Martina , Roeb Martin , Schmu¨cker Martin , Sattler Christian , Pitz-Paal Robert
Published: June 2009

A two-step thermochemical cycle for solar hydrogen production using mixed iron oxides as the metal oxide redox system has been investigated. A reactor concept has been developed in which the metal oxide is fixed on multi-channelled honeycomb ceramic supports capable of adsorbing solar irradiation. In the solar furnace of DLR in Cologne coated honeycomb structures were tested in a solar receiver-reactor with respect to their water splitting capability and their long term stability. The concept of this new reactor design has proven feasible and constant hydrogen production during repeated cycles has been shown. For a further optimization of the process and in order to gain reliable performance predictions more information about the process especially concerning the kinetics of the oxidation and the reduction step are essential. To examine the kinetics of the water splitting and the regeneration step a test rig has been built up on a laboratory scale. In this test rig small coated honeycombs are heated by an electric furnace. The honeycomb is placed inside a tube reactor and can be flushed with water vapour or with an inert gas. A homogeneous temperature within the sample is reached and testing conditions are reproducible. Through analysis of the product gas the hydrogen production is monitored and a reaction rate describing the hydrogen production rate per gram ferrite can be formulated. Using this test set-up, SiC honeycombs coated with a zinc-ferrite have been tested. The influences of the water splitting temperature and the water concentration on the kinetics of the water splitting step have been investigated. A mathematical approach for the reaction rate was formulated and the activation energy was calculated from the experimental data. An activation energy of 110 kJ/mole was found.
Dynamic Modeling of a Novel Cooling, Heat, Power, and Water Microturbine Combined Cycle
Authors: Ryu ChoonJae , Srinivasan Aditya , Tiffany David R. , Crittenden John F. , Lear William E. , Sherif S. A.
Published: June 2009

The Power, Water Extraction, and Refrigeration (PoWER) engine has been investigated for several years as a distributed energy (DE) system among other applications for civilian or military use. Previous literature describing its modeling and experimental demonstration have indicated several benefits, especially when the underlying semi-closed cycle gas turbine is combined with a vapor absorption refrigeration system, the PoWER system described herein. The benefits include increased efficiency, high part-power efficiency, small lapse rate, compactness, low emissions, lower air and exhaust flows (which decrease filtration and duct size) and condensation of fresh water. The present paper describes the preliminary design and its modeling of a modified version of this system as applied to DE system, especially useful in regions which are prone to major grid interruptions due to hurricanes, under-capacity, or terrorism. In such cases, the DE system should support most or all services within an isolated service island, including ice production, so that the influence of the power outage is contained in magnitude and scope. The paper describes the rather straightforward system modifications necessary for ice production. However, the primary focus of the paper is on dynamic modeling of the ice making capacity to achieve significant load-leveling during the summer utility peak, hence reducing the electrical capacity requirements for the grid.
Operation of a CCHP System Using an Optimal Energy Dispatch Algorithm
Authors: Cho Heejin , Eksioglu Sandra D. , Luck Rogelio , Chamra Louay M.
Published: June 2009

The Combined Cooling, Heating, and Power (CCHP) systems have been widely recognized as a key alternative for thermal and electric energy generation because of the outstanding energy efficiency, reduced environmental emissions, and relative independence from centralized power grids. Nevertheless, the total energy cost of CCHP systems can be highly dependent on the operation of individual components and load balancing. The latter refers to the process of fulfilling the thermal and electrical demand by partitioning or “balancing” the energy requirement between the available sources of energy supply. The energy cost can be optimized through an energy dispatch algorithm which provides operational/control signals for the optimal operation of the equipment. The algorithm provides optimal solutions on decisions regarding generating power locally or buying power from the grid. This paper presents an initial study on developing an optimal energy dispatch algorithm that minimizes the cost of energy (i.e., cost of electricity from the grid and cost of natural gas into the engine and boiler) based on energy efficiency constrains for each component. A deterministic network flow model of a typical CCHP system is developed as part of the algorithm. The advantage of using a network flow model is that the power flows and efficiency constraints throughout the CCHP components can be readily visualized to facilitate the interpretation of the results. A linear programming formulation of the network flow model is presented. In the algorithm, the inputs include the cost of the electricity and fuel and the constraints include the cooling, heating, and electric load demands and the efficiencies of the CCHP components. This algorithm has been used in simulations of several case studies on the operation of an existing micro-CHP system. Several scenarios with different operational conditions are presented in the paper to demonstrate the economical advantages resulting from optimal operation.
Design of a Quench Device for Synthesis and Hydrolysis of Zn Nanoparticles: Flow Modeling and Experiments
Authors: Alshare Aiman , Abu Hamed Tareq , Bru¨lhart Marc , Venstrom Luke , Davidson Jane H.
Published: June 2009

The synthesis and hydrolysis of zinc nanoparticles are carried out in a tubular reactor. A key component of the reactor is a coaxial jet quench device. Three co-axial and multi-inlet confined jets mix Zn(g), steam and argon to produce and hydrolyze zinc nanoparticles. The performance of the quench device is assessed with computational fluid dynamic modeling and measurements of hydrogen conversion and particle size and composition. Numerical data elucidate the impact of varying jet flow rates on temperature and velocity distributions within the reactor. Experiments produce hydrogen conversions of 61 to 79%. Particle deposition on sections of the reactor surface above 650 K favors hydrolysis. Residence time for in-flight particles is less than one second and these particles are partially hydrolyzed.
Catalytic Pyrolysis of Biomass: Yields and Characterization of the Products
Authors: Ates Funda , Putun Ayse Eren , Putun Ersan
Published: June 2009

Terpene hydrocarbons are high energy capacity hydrocarbons. The most known terpenoid biomass is Euphorbiaceae family. Euphorbia rigida, a member of Euphorbiaceae, was used as the biomass feedstock and natural zeolite was used as the catalyst in this study. In the experimental studies, firstly the raw material was analysed for its moisture, ash, volatile matter and fixed carbon. Then experiments were carried out in steam atmosphere in a fixed-bed reactor with a heating rate of 7 K/min, pyrolysis temperature of 823 K and mean particular size of 0.55 mm by mixing the catalyst to feedstock in different percentages. Experiments were performed with the catalyst ratios of 5, 10, 20 and 25 (weight-%) under steam atmosphere with the velocities of 12, 25 and 52 cm3/min to determine the effect of catalyst and steam on the product yields and bio-oil composition. Steam velocities were considered as the average steam velocities in the inlet tube of the reactor. The maximum bio-oil was reached to a value of 39.7% when using catalyst ratio of 20% and steam flow rate of 25 cm3/min. Pyrolysis oils were examined by using elemental analysis, IR and 1H-NMR spectroscopy. The liquid products were also fractionated by column chromatography and the gas chromatographic analysis of n-pentane eluate was performed.
Synergization of Clean Energy Utilization, Clean Technology Development and Controlled Clean Environment Through Thermally Activated Desiccant Cooling System
Authors: Enteria Napoleon , Yoshino Hiroshi , Mochida Akashi , Takaki Rie , Satake Akira , Yoshie Ryuichiro , Mitamura Teruaki , Baba Seizo
Published: June 2009

The global problems of energy supply and demand, climatic change due to artificial global warming, and providing economical and clean human comfortable condition are a complex issue. These problems have become globally political, economical and technological in the center stage of global arena. Utilization of alternative energy resources which are clean and green, hand in hand with the development of alternative clean and green technologies can indeed reduce the global and environmental problems. This paper invasions the idea of harnessing the power of clean energy resources and of developing clean technology for the production of clean environmental conditions. Synergization of clean energy resources, clean technologies and production of clean environment is implemented through the thermally activated desiccant cooling system. The experimental facility is constructed which consists of thermal energy system, desiccant cooling system and the artificially controlled environmental conditions for experimental evaluation purposes. Preliminary experimental investigation is being undertaken to evaluate the performance of the thermal energy system and of the desiccant cooling system. Based on the results, thermal energy system is functioning to its expectations. However, the desiccant cooling system still needs improvement to optimize its cooling capacity. With this study, practical combination of clean energy utilization and of clean technology development for the production of clean environment is possible through proper design and implementation.
Greenhouse Gas Emissions Reduction Potentials in Iranian Electricity Generation Sector and Comparison With Canada
Authors: Zabihian Farshid , Fung Alan S.
Published: June 2009

In recent years, greenhouse gas (GHG) emissions and their potential effects on the global climate change have been a worldwide concern. Based on International Energy Agency (IEA), power generation contributes half of the increase in global GHG emissions in 2030. In the Middle East, Power generation is expected to make the largest contribution to the growth in carbon-dioxide emissions. The share of the power sector in the region’s total CO2 emissions will increase from 34% in 2003 to 36% in 2030. Therefore, it is very important to reduce GHG emissions in this industry. The purpose of this paper is to examine greenhouse gas emissions reduction potentials in the Iranian electricity generation sector through fuel switching and adoption of advanced power generation systems and to compare these potentials with Canadian electricity generation sector. These two countries are selected because of raw data availability and their unique characteristics in electricity generation sector. To achieve this purpose two different scenarios have been introduced: Scenario #1: Switching existing power stations fuel to natural gas. Scenario #2: Replacing existing power plants by natural gas combined-cycle (NGCC) power stations (The efficiency of NGCC is considered to be 49%). The results shows that the GHG reduction potential for Iranian steam power plants, gas turbines and combined cycle power plants in first scenario are 9.9%, 5.6%, and 2.6%, respectively with the average of 7.6%. For the second scenario the overall reduction of 31.9%, is expected. The average reduction potential for Canadian power plants for scenario number 1 and 2 are 33% and 59%, respectively. As it can be seen, in Canada there are much higher potentials to reduce GHG emissions. The reason is that in Canada majority of power plants use coal as the primary fuel. In fact almost 73% of electricity in thermal power stations is generated by coal. Whereas in Iran almost all power plants (with some exceptions) are dual fuels and 77% of energy consumed in Iran’s thermal power plants come from natural gas. Also, 21% of total electricity generated in Iran is produced by combined-cycle power plants.
Energy and Exergy Analysis of Gasifier-Based Coal-to-Fuel Systems
Authors: Zhu Yunhua , Somasundaram Sriram , Kemp James W.
Published: June 2009

Interests in coal-to-liquid (CTL) and other fuels have grown greatly in the last couple of years with steadily increasing oil prices. National energy security concerns related to liquid transportation fuels also have revived interests in alternative liquid fuel sources. Coal-to-fuel technologies feature high efficiency energy conversion and environmental advantages. While a number of factors are driving coal-to-fuel projects forward, there are several barriers to wide commercialization, such as financial, construction, operation, and technical risks. The purpose of this study is to investigate the performance features of CTL and other coal-to-fuel systems based on different gasification technologies. The target products are Fischer-Tropsch (F-T) crude and synthesis natural gas (SNG). Two types of entrained-flow gasifier based coal-to-fuel systems are simulated and their performance features are discussed. One is single-stage water quench (WQ) cooling entrained-flow gasifier, and another is two-stage syngas cooling (SC) entrained-flow gasifier. The conservation of energy (first law of thermodynamics) and the quality of energy (second law of thermodynamics) for the systems are both investigated. The results of exergy analysis provide insights about the potential targets for technology improvement. The features of different gasifier-based coal-to-fuel systems are discussed. The results provide information about the research and development priorities in future.
Design and Development of a Gas-Engine-Driven Heat Pump
Authors: Mahderekal Isaac Y. , Gaylord Robert G. , Young Tommis , Hinderliter Kevin , Vineyard Ed
Published: June 2009

Improved air-conditioning technology has the greatest potential impact on the electric industry compared to any other technology that uses electricity particularly during summer peak electric demand. Gas engine-driven units can provide overall peak load reduction and electric grid relief for summer peak demand. Peak-load conditions can lead to high electricity prices, power quality problems, and grid system inefficiencies, and even failures. Improved air-conditioning technology thus has the greatest potential impact on the electric grid compared to other technologies that use electricity. Thermally-activated systems, such as natural gas engine-driven heat pumps, can provide overall peak load reduction and electric grid relief for summer peak demand. This paper describes the development of an innovative 10 refrigeration ton (RT) natural gas engine-driven heat pump (GHP) for commercial application. The unit was tested at various Air Conditioning and Refrigeration Institute (ARI) heating and cooling conditions in a psychrometric chamber at Oak Ridge National Laboratory. The gas COP at 47°F rating condition exceeded the goal of 1.6 at both high and intermediate engine speeds. The gas COP in cooling mode also exceeded the goal of 1.2 at 95°F rating condition. In this study, principles of operation, unit performance and benefits are discussed.
Development Prospects of Distributed Energy System in China
Authors: Shi Guohua , Wang Songling , Jing Youyin , Gao Yuefen
Published: June 2009

With the rapid economic development, the energy demand is rising and energy-related greenhouses gas emissions are growing rapidly in China. The usage percent of renewable energy in use is still low while the energy consumption is still increasing. Due to the expanding pressure from energy demand, environment concerns and society issues, distributed energy systems (DESs), especially combined heat and power (CHP), are encouraged and expected to play a greater role by the government. This paper mainly seeks to explore and answer some of questions. Firstly, the different technologies of various DES options are briefly reviewed. Then the question of why distributed energy systems should be developed in China is considered. Recent trends and current patterns of energy supply and use in China are also discussed. Some typical distributed energy systems used in China are introduced. This article also discusses what barriers need be overcome if China wishes to move towards a sustainable energy future. Finally, several suggestions are proposed to favor the wide application of DES in China. It is concluded that DES is a good option with respect to China’s sustainable development that has institutional, market and regulatory support.
Experimental Investigation of a Packed-Bed Solar Reactor for the Steam-Gasification of Biomass Charcoal
Authors: Piatkowski Nicolas , Wieckert Christian , Steinfeld Aldo
Published: June 2009

Gasification of coal, biomass, and other carbonaceous materials for high-quality syngas production is considered using concentrated solar energy as the source of high-temperature process heat. The solar reactor consists of two cavities separated by a SiC-coated graphite plate, with the upper one serving as the radiative absorber and the lower one containing the reacting packed bed that shrinks as the reaction progresses. A 5-kW prototype reactor with an 8 cm-depth, 14.3 cm-diameter cylindrical bed was fabricated and tested in the High-Flux Solar Simulator at PSI, subjected to solar flux concentrations up to 2300 suns. Beech charcoal was used as a model feedstock and converted into high-quality syngas (predominantly H2 and CO) with packed-bed temperatures up to 1500 K, an upgrade factor of the calorific value of 1.33, and an energy conversion efficiency of 29%. Pyrolysis was evident through the evolution of higher gaseous hydrocarbons during heating of the packed bed. The engineering design, fabrication, and testing of the solar reactor are described.
Electricity Generation From a Compound Parabolic Concentrator Coupled to a Thermoelectric Module
Authors: Mgbemene Chigbo A. , Duffy John , Sun Hongwei , Onyegegbu Samuel O.
Published: June 2009

Generating electricity from the sun using a combination of a compound parabolic concentrator (CPC) and a thermoelectric module (TEM) has been studied. The system was modeled, analyzed and tested. The model equations and the methodology used for the demonstration are presented and experimentally validated. The experimental setup comprised a manually fabricated CPC placed on a commercially available TEM. The results showed that the combination can generate and sustain enough power for a small appliance. It was also shown that there is enough dissipated heat from the system which could be harnessed for additional uses. The cost is still high, about $35/Wp, but if credit is given for the thermal energy the initial cost goes down.
Performance of Solid Particle Receivers With or Without the Protection of an Aerowindow
Authors: Tan Taide , Chen Yitung , Chen Zhuoqi
Published: June 2009

A solid particle solar receiver (SPSR) is a direct absorption central receiver that uses solid particles enclosed in a cavity to absorb concentrated solar radiation. However, the existing open aperture lowers the overall efficiency by convection heat transfer. Aerowindows have the potential of increasing the efficiency of an SPSR by reducing convective losses from an open receiver aperture and eliminate reflection, convection and reradiation losses from a comparable glass window. Aerodynamic windows consist of a transparent gas stream, which is injected from an air jet, across the receiver aperture to isolate its interior from the surrounding atmosphere. Even though, the wind conditions may still have important effect on the performance of SPSRs. In the present paper, the wind effect on the performance of an SPSR is investigated numerically. The mass, momentum and energy exchange between the solid particle and air flow are simulated by the two-way coupling Euler-Lagrange method in the realizable k-ε turbulence 3D model. The independence of the calculating domain is studied in order to select a proper domain for the numerical simulation. Solar ray tracing method is employed in calculating the solar radiation energy. The numerical investigation of the performance of the SPSR is focusing on optimizing the prototype design and finding out the best working condition for the SPSR. In order to investigate the influences of the wind speed and wind blowing direction on the performance of the receiver, different wind conditions of and different air jet injection conditions are simulated numerically. The cavity thermal efficiencies are calculated and the optimal injection conditions are analyzed for different wind conditions.
Net Energy for Concentrated Solar Power in Chile
Authors: Escobar Rodrigo , Larrain Teresita
Published: June 2009

The Chilean Energy Policy calls for 15 percent of new power generation capacity to come from renewable energy sources from 2006 to 2010, and then a 5% of electric energy generated from renewable energy sources with gradual increases in order to reach 10% by 2024. Neither the government nor the power generation sector plans mention solar energy to be part of the renewable energy initiative. Part of this apparent lack of interest in solar energy might be due to the absence of a valid solar energy database, adequate for energy system planning activities. Monthly means of solar radiation are used in order to estimate the solar fraction for a 100 MW plant for four given locations. Our analysis considers two cases: operation during sunlight hours, and continuous operation during 24 hours a day. A net energy analysis for concentrated solar power (CSP) plants in Chile is then performed, considering the energy costs of manufacturing, transport, installation, operation and decommissioning. The results indicate that the CSP plants are a net energy source in three of the four locations, when operating in sunlight-only mode. This is due to the lower radiation levels available at that location, which implies a high fossil fuel back-up fraction. In the continuous operation mode, the CSP plants become fossil fuel plants with solar assistance, and therefore all locations display negative net energy. Based on this result, the back-up fraction required for the plants to be net energy sources is estimated from the EROEI as function of the back-up fraction. It is estimated that the net energy analysis is a useful tool for determining under which conditions a CSP plant becomes a net energy source, and thus can be utilized in order to define geographical locations and operation conditions where they can be considered renewable energy sources.
Sustainable Energy for Deployed Military Bases
Authors: Hartranft Thomas J.
Published: June 2009

The U.S. military conducts a full spectrum of contingency operations in which it provides humanitarian assistance, logistical support, peacekeeping stability functions, and reconstruction activities. It is becoming increasingly important to incorporate the concept of “sustainability” into these operations. Making contingency operations more sustainable will provide force multiplier aspects that increase operational efficiencies and reduce logistical burdens and costs. The military requires enormous energy resources to maintain its mission readiness, which contributes greatly to logistical burdens and costs. A wide range of sustainability considerations relate to the cross-functional use of energy in contingency operations, from the interface with a host nation’s infrastructure; temporary construction practices; fuel convoys; cascading material use; the handling and treatment of waste, water, and hazardous materials; logistics footprint, etc. This paper describes military issues that will affect deployed base mission requirements and future investment policies. It also describes the ongoing process to develop an Army vision for sustainable contingency operations. This vision will consider the integration of cross-functional energy uses and establish sustainable operational requirements and investment policies. These insights are also applicable to many international humanitarian situations.
Numerical Study of Temperature Field in BEPCII Interaction Region
Authors: Li Xunfeng , Zheng Lifang , Wang Li , Ji Quan
Published: June 2009

The temperature field of the beam pipe was calculated at the maximum heat loads and designed flow rates of the cooling liquids. The maximum difference between the predicted and measured temperature on the outer surface of the beam pipe was found to be 0.6 K. In addition, the temperature field between the beam pipe and the inner barrel of the main drift chamber (MDC) was calculated assuming natural convection heat transfer of the air in the enclosed cavity under three different conditions. The results of the calculation showed that only the use of insulation covers on the transition sections of the beam pipe keeps the temperature of the inner barrel in the range of 293.0±1.0 K. The thermal conductivity of the heat insulators under the heat insulation covers must be less than 0.5 W/(m·K).
Cost Competitive Implementation of Community Shared Microgrids
Authors: Hammonds James S.
Published: June 2009

Microgrids are systems of linked distributed energy (DE) generation sources that provide power for a relatively small number of users. In this work, we show how microgrids can be used to reduce emissions and deliver power with an annual amortized cost that is competitive with grid power. To perform the analysis, average hourly electrical load profiles for residential customers in Washington, DC were obtained from the utility company (Pepco). Hot water and heating fuel consumption is modeled computationally using prototype building characteristics. The energy consumption data is then used with a computer-based model to analyze grid-tied microgrids. The DE sources examined in this work are photovoltaic arrays and combined heat and power (CHP). The cost and CO2 emissions for the microgrid are compared to the case where power is drawn solely from the grid. We show that when DE capacity is optimally utilized, the microgrid is cost competitive, and the cost to reduce emissions is lowered.
The Performance Improvement of a 70kWe Natural Gas CHP System
Authors: Fu Lin , Zhao Xiling , Zhang Shigang , Jiang Yi , Li Hui , Yang Weiwei , Sun Zuoliang
Published: June 2009

It is well known that combined heating and power (CHP) generation permits the energy of the fuel to be more efficiently than electric and thermal separate generation. The paper deals with natural gas CHP system with a 70kWe gas-powered internal combustion engine (ICE), which has been set up at the Tsinghua University energy-saving building, in Beijing, China. The system is composed of an ICE, a flue gas heat exchanger and other heat exchangers. The conventional system’s characteristics is that the gas engine generates power on-site, and the exhaust of the gas engine is recovered by a high temperature flue gas-water heat exchanger, and the jacket water heat is recovered by a water-water heat exchanger to supply heat for district heating system. In order to improve the system’s performance, an innovative system with absorption heat pump is adopted. The exhaust of the gas engine drives an absorption heat pump to recover the flue gas sensible heat and further recover the latent heat, so the outlet temperature of the exhaust could be lowered to 50°C. In this paper, the electrical and thermal performance of the innovative system were tested and compared with conventional cogeneration systems. The test and comparison results show that the innovative CHP system could increase the heat utilization efficiency 10% in winter. All the results provide important insight into CHP performance characteristics and could be valuable references for CHP system’s improvements.
The Steady and Dynamic Performance of an Innovative Natural Gas CHP System
Authors: Fu Lin , Zhao Xiling , Zhang Shigang , Jiang Yi , Li Hui , Yang Weiwei , Sun Zuoliang
Published: June 2009

In the last decade, technological innovation and changes in the economic and regulatory environment have resulted in increased attention to distributed energy systems (DES). Combined heating and power (CHP) systems based on the gas-powered internal combustion engine (ICE) are increasingly used as small-scale distribution co-generators. This paper describes an innovative ICE-CHP system with an exhaust-gas-driven absorption heat pump (AHP) that has been set up at the energy-saving building in Beijing, China. The system is composed of an ICE, an exhaust-gas-driven AHP, and a flue gas condensation heat exchanger (CHE), which could recover both the sensible and latent heat of the flue gas. The steady performance and dynamic response of the innovative CHP system with different operation modes were tested. The results show that the system’s overall efficiency could reach above 90% based on lower heating value (LHV) of natural gas; that is, the innovative CHP system could increase the heat utilization efficiency 10% compared to conventional CHP systems, and the thermally activated components of the system have much more thermal inertia than the electricity generation component. The detailed test results provide important insight into CHP performance characteristics and could be valuable references for the control of CHP systems. The novel CHP system could take on a very important role in the CHP market.
Conversion of Seawater to Fresh Water: An Experiment With a Solar Assisted Heat Pump
Authors: Hawlader M. N. A. , Amin Zakaria Mohd.
Published: June 2009

Seawater desalination is one of the most suitable areas for the utilization of solar thermal energy due to the coincidence, in many places of the world, of water scarcity, seawater availability and good levels of solar irradiation. The solar assisted heat pump provides a new horizon in the seawater desalination. Experiments were conducted on solar assisted heat pump desalination system under meteorological conditions of Singapore. This system uses two types of flat-plate solar collectors. One is called evaporator-collector which is entirely unglazed. The other type is single-glazed collector used for feed water heating. A single stage MED (multi-effect distillation) evaporator is used in this system and the refrigerant R134a is used in the heat pump. The system has a Performance Ratio (PR) of around 1.3 and water production capability of 0.6 to 0.9 kg/hr. The Coefficient of Performance (COP) of the heat pump reaches a maximum value of about 9 for the meteorological conditions of Singapore.
CO2 Emission Abatement in CC-IGCC Power Plants: Energy and Economic Comparisons
Authors: Gambini Marco , Vellini Michela
Published: June 2009

In this paper two methodologies, able to avoid CO2 dispersion in atmosphere, have been analyzed: • treating exhaust gases in order to remove, liquefy and store the produced carbon dioxide; • de-carbonizing fossil fuels before using them in the combustion in order to inhibit completely carbon dioxide production. These methodologies have been implemented in advanced power plants based on gas turbine: a combined cycle power plant (CC), fed by natural gas, and an integrated gasification combined cycle (IGCC), fed by coal. The exhaust gas treatment is based on a chemical process of absorption, while the fossil fuel decarbonization is based on partial oxidation of methane, steam methane reforming and coal gasification. These systems require material and energetic integrations with the power sections and so the best interconnections must be investigated in order to obtain good overall performance. With reference to thermodynamic and economic performance, significant comparisons have been made between the above mentioned reference plants. An efficiency decrease and an increase in the cost of electricity have been obtained when power plants are equipped with systems able to reduce CO2 emissions. However, in order to obtain low CO2 emissions when coal is used, the coal decarbonization must be implemented: in this case it is possible to attain a global efficiency of about 38%, a specific emission of 0.1117 kg/kWh and an increase of kWh cost of about 32%. Vice versa, in order to obtain low CO2 emissions when natural gas is used, the exhaust gas treatment must be implemented: in this case it is possible to attain a global efficiency of about 50.7%, a specific emission of 0.0391 kg/kWh and an increase of kWh cost of about 15%. The clean use of coal seems to have good potential because it allows low energy penalizations (about 7.5 percentage points) and economic increases of about 32%. Because of the great availability, the homogeneous distribution and the low cost of this fuel, these results seem to be very interesting especially in the viewpoint of a transition towards the “hydrogen economy”, based, at least in the medium term, on fossil fuels.
Empirical Assessment of the Impact of Power Sector Reforms in Africa: A Study of the Generation, Transmission and Distribution Sectors
Authors: Gboney William Kwasi , Cubbin John , Dassiou Xeni
Published: June 2009

This paper is based on a research study which was carried out, to empirically assess the impact of power sector reforms, comprising privatization, competition and regulatory reforms in 29 African countries, for the period 1988–2005. The list of countries in the research sample is shown in Appendix 1. The main findings for the generation sector is that, in Africa, though energy sector regulation backed by sector law can bring about favorable outcomes, better results are likely to be achieved if the regulatory agency has been in existence for at least 3 years, and it co-exists with either competition ‘for’ the market or private sector participation. On private sector participation, the presence of Independent Power Producers, management contracts and private shareholding in generation assets, can enhance generation sector performance. The results on the transmission system seem to indicate that though the establishment of a regulatory agency can reduce transmission system loss level, this outcome is likely to be achieved if the regulatory agency has been existence for at least 3 years. On distribution system loss, it emerged that the sole existence of a regulatory agency may not be enough to influence a downward trend in distribution system loss level, unless the market, permits the co-existence of competition ‘for’ the market, with a regulatory agency.
Viable Tailored Organic Fertilizer Alternatives From Waste Produced by Bio-Diesel Extraction Process and Tobacco Industry
Authors: Chaturvedi Shivani , Satya Santosh , Kaushik Geetanjali , Chel Arvind
Published: June 2009

Rapid depletion of conventional sources of energy and the growing environmental concern of their use warrant urgent attention to look for suitable energy alternatives. In this regard the seeds of Jatropha curcas, constituting 40–50% bio-crude oil are considered as one of the most promising alternatives for the production of bio-diesel. It is estimated that about 1.5 tons de-oiled cake is produced from seeds obtained from one hectare of plantation, utilized for bio-diesel extraction process. Being non-edible due to its toxic contents, cost effective safe disposal of this by-product can only be possible if there is a meaningful utilization. India’s tobacco industry is the second largest in the world after China, having vast area under tobacco cultivation. The wastes from tobacco industry lead to significant environmental pollution that has severe impacts on both flora and fauna. A few studies on this aspect have revealed that Jatropha and tobacco bio-wastes have potential to be used as organic fertilizers. The present study aims at developing appropriate bio-processes and formulation that utilize Jatropha seed cake and waste of tobacco industry as organic fertilizer for improving the growth of Chrysanthemum, a flower variety valued for its beauty and fragrance and having wide applications in cosmetic and perfumery products. Pot experiments were carried out by adding specific proportions of Jatropha de-oiled cake and tobacco waste to normal garden soil. The growth and morphological parameters of Chrysanthemum plants grown in pots prepared by the treated soil were monitored for 4–5 months and the results were recorded. The results have been encouraging as the treatments lead to a significant enhancement in flower growth as well as yield. 11.5% increase in number of buds per plant was recorded for treated soil as compared to the control soil. The number of flowers per plant also recorded an increase of 16% to 24% due to the effect of formulation applied to the soil. Similar trends were observed for other parameters like flower size, flower head size, flower weight and ray floret number. Through experimentation new composted organic fertilizer formulations, tailored to specific commercial crop has been developed. The research findings would enable these bio-wastes to be used as a viable alternative to the energy intensive chemical fertilizers for floriculture, thus contributing to the mitigation of global climate change. This addition in the value chain would improve the financial viability of bio-diesel extraction process. This new synergistic organic fertilizer formulation when used as an alternative to nitrogenous chemical fertilizers would also provide an opportunity to earn carbon credits which is estimated to be € 67904 millions/year.
Performance Modeling of Desiccant Wheels: 1 — Model Development
Authors: Zhai Chaoqin , Archer David H. , Fischer John C.
Published: June 2009

This paper presents the development of an equation based model to simulate the combined heat and mass transfer in the desiccant wheels. The performance model is one dimensional in the axial direction. It applies a lumped formulation in the thickness direction of the desiccant and the substrate. The boundary conditions of this problem represent the inlet outside/process and building exhaust/regeneration air conditions as well as the adiabatic condition of the two ends of the desiccant composite. The solutions of this model are iterated until the wheel reaches periodic steady state operation. The modeling results are obtained as the changes of the outside/process and building exhaust/regeneration air conditions along the wheel depth and the wheel rotation. This performance model relates the wheel’s design parameters, such as the wheel dimension, the channel size and the desiccant properties, and the wheel’s operating variables, such as the rotary speed and the regeneration air flowrate, to its operating performance. The impact of some practical issues, such as wheel purge, residual water in the desiccant and the wheel supporting structure, on the wheel performance has also been investigated.
The Development of a Model for a Solar-Fired, Single-Effect, Absorption Chiller
Authors: Hinderliter Kevin E. , Mahderekal Isaac Y. , Boehm Robert F.
Published: June 2009

This study presents the concept, functionality, and economics of a solar-fired, single-effect, absorption air conditioning system. The goal of this project was to develop a mathematical model to determine efficiencies and capacities, which are then compared with a traditional 28 kW (8 ton) packaged vapor compression system. This comparison is then used to determine economic conclusions. The thermal system being examined is part of a proposed research and development project located in Phoenix, Arizona. This specific system will contain a six-module, single-axis, concentrating solar collector, a 119 gallon (450 L) storage tank, and a 35kW chiller. Using MatLab with Typical Meteorological Year 2 (TMY2) weather data [1], a model was created from readily available manufacturer specifications. After completing the model it was determined that the annual savings can range from $3,448 to $1,737 with simple payback periods of 18 to 36 years depending on collector efficiencies and current electrical rates. The model also proved that the proposed cooling system can supply over 20 kW of continuous cooling for 8 hours on a typical summer day.
Motion Energy Harvesting Using Catch-and-Release Mechanism
Authors: Hendrickson Brian S. , Brown Stuart B.
Published: June 2009

Small-scale motion energy harvesting has garnered significant interest in recent years, especially given advances in piezoelectric materials, but with limited commercial application. Most harvesting methods to date, including those employing magnetic induction, have focused on coupled resonance. Such harvesters are tuned to resonate with their excitation source and have shown promise in capturing moderately high-frequency (>10Hz), low-displacement motion that is steady. However, coupled harvesters lose efficiency significantly when a source deviates slightly in frequency. They also require large masses and/or buoyant volumes to efficiently capture low frequency (<10Hz) motion. We have been developing a novel technology that combines electromagnetic induction with a proprietary catch-and-release mechanism that absorbs an input motion and then releases it at a much higher frequency to improve conversion efficiency. The energy harvester is simple, compact, and insensitive to excitation frequency. Initial prototypes have demonstrated power densities and specific powers many multiples greater than the best-performing, commercial vibration harvester. We have also developed a validated computer model of the system that indicates that performance could be improved 2–4 times over initial prototypes.
CFD Modeling of PEM Fuel Cell’s Flow Channels
Authors: De Giorgi Maria Grazia , Ficarella Antonio
Published: June 2009

The present work presents a three-dimensional, non-isothermal computational model of PEMFC, implemented in the CFD code Fluent. The model accounts for all major transport phenomena, including: water and proton transport through the membrane; electrochemical reaction; transport of electrons; transport and phase change of water in the gas diffusion electrodes; diffusion of multi-component gas mixtures in the electrodes; and mass transport in the gas flow channels. First, the polarization behavior or steady state performance of the PEMFC has been simulated and then the transient response subjected to a variable load has been studied. In the steady state analysis, the polarization curves, obtained by single phase and two-phase numerical simulations, have been compared with the experimental data given in literature. A good agreement is evident for the curve given by the two-phase simulations, while the single-phase model is unable to reproduce the experimental data at the high current densities. A parametric study has been done to validate the model and the predicted polarization curves have been compared with experiments. Finally unsteady simulations have been performed. The effect of the rate of change in cell voltage on cell performance for three different rates have been shown. The transient results demonstrate that current density overshoots the stabilized state value when cell voltage is abruptly decreased.