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Cogeneration System (cogeneration + system)

Distribution by Scientific Domains

Engineering	77%

Kinds of Cogeneration System

residential cogeneration system

Selected Abstracts

Proposal and evaluation of a gas engine and gas turbine hybrid cogeneration system in which cascaded heat is highly utilized

ELECTRICAL ENGINEERING IN JAPAN, Issue 3 2009
Pyong Sik Pak
Abstract A high-efficiency cogeneration system (CGS) is proposed for utilizing high-temperature exhaust gas (HTEG) from a gas engine (GE). In the proposed system, for making use of heat energy of HTEG, H2O turbine (HTb) is incorporated and steam produced by utilizing HTEG is used as working fluid of HTb. HTb exhaust gas is also utilized for increasing power output and for satisfying heat demand in the proposed system. Both of the thermodynamic characteristics of the proposed system and a gas engine CGS (GE-CGS) constructed by using the original GE are estimated. Energy saving characteristics and CO2 reduction effects of the proposed CGS and the GE-CGS are also investigated. It was estimated that the net generated power of the proposed CGS has been increased 25.5% and net power generation efficiency 6.7%, compared with the original GE-CGS. It was also shown that the proposed CGS could save 27.0% of energy consumption and reduce 1137 t-CO2/y, 1.41 times larger than those of GE-CGS, when a case study was set and investigated. Improvements of performance by increasing turbine inlet temperature were also investigated. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 166(3): 37, 45, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20708 [source]

Performance evaluation of an electricity base load engine cogeneration system

INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 9 2010
Denilson Boschiero do Espirito Santo
Abstract Decentralized electricity production by cogeneration can result in primary energy economy, as these systems operate with a high-energy utilization factor (EUF), producing electricity and recovering energy rejected by the prime mover to meet site thermal demands. Because energy demands in buildings vary with such factors as the hour of the day, level of activity and climatic conditions, cogeneration case studies should consider different system configurations, energy demand profiles and climatic profiles. This paper analyzes an engine cogeneration system as an integrated thermal system by means of a computational simulation program. The simulation takes into account characteristics of the system, characteristics of the pieces of equipment, design choices and parameters, the variability of operating conditions, site energy demand profiles and climatic data to evaluate the performance of the cogeneration plant. Performance evaluation is based on: (i) the EUF, (ii) the exergy efficiency and (iii) primary energy savings analysis. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Dynamic energy and exergy analyses of an industrial cogeneration system

INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 4 2010
Yilmaz Yoru
Abstract The study deals with the energetic and exergetic analyses of a cogeneration (combined heat and power, CHP) system installed in a ceramic factory, located in Izmir, Turkey. This system has three gas turbines with a total capacity of 13,MW, six spray dryers and two heat exchangers. In the analysis, actual operational data over one-month period are utilized. The so-called CogeNNexT code is written in C++ and developed to analyze energetic and exergetic data from a database. This code is also used to analyze turbines, spray dryers and heat exchangers in this factory. Specifications of some parts of system components have been collected from the factory. Based on the 720,h data pattern (including 43,200 data), the mean energetic and exergetic efficiency values of the cogeneration system are found to be 82.3 and 34.7%, respectively. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Second law analysis of a natural gas-fired gas turbine cogeneration system

INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 8 2009
B. V. Reddy
Abstract The influence of operating conditions such as reheat, intercooling, ambient temperature and pressure ratio are analyzed from a second law perspective on the performance of a natural gas-fired gas turbine cogeneration system. The effect of these operating parameters on carbon dioxide emissions is also discussed. The second law efficiency of gas turbine cogeneration system increases markedly with reheat option. Higher pressure ratios lead to decreased second law cogeneration efficiency but this effect can be reduced with a higher level of reheat option. The effect of intercooling on second law efficiency is strongly related to pressure ratio with higher pressure ratios significantly decreasing efficiency. The second law efficiency is not so sensitive to the environment temperature for levels of reheat or intercooling greater than 50%. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Study of a fuel cell network with water electrolysis for improving partial load efficiency of a residential cogeneration system

INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 8 2006
S. Obara
Abstract A fuel cell energy network which connects hydrogen and oxygen gas pipes, electric power lines and exhaust heat output lines of the fuel cell cogeneration for individual houses, respectively, is analysed. As an analysis case, the energy demand patterns of individual houses in Tokyo are used, and the analysis method for minimization of the operational cost using a genetic algorithm is described. The fuel cell network system of an analysis example assumed connecting the fuel cell cogeneration of five houses. If energy is supplied to the five houses using the fuel cell energy network proposed in this paper, 9% of city gas consumption will be reduced by the maximum from the results of analysis. Two per cent included with 9% is an effect of introducing water electrolysis operation of the fuel cells, corresponding to partial load operation of fuel cell cogeneration. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Cost structure of CGAM cogeneration system

INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 13 2004
Ho-Young Kwak
Abstract The cost structure of the CGAM system, a predefined cogeneration system suggested to unify the different methodologies of thermoeconomic analysis, was investigated by using a thermoeconomic method called modified productive structure analysis (MOPSA). An emphasis has been specially put on how the cost structure of the system is affected by the chosen level of aggregation that specifies the subsystems. It has been found that the unit cost of products is dependent on the chosen level of aggregation of the system only when one considers the entropy flow as one of the parameters to determine the unit cost of products. Copyright © 2004 John Wiley & Sons, Ltd. [source]

Application of a chemical heat pump to a cogeneration system

INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 2 2001
Yukitaka Kato
Abstract The feasibility of a proposed system that combines a magnesium oxide/water chemical heat pump and a diesel engine as a cogeneration system is discussed based on experimental results. The combined system is intended to utilize the waste heat discharge from the engine by means of the chemical heat pump and to level the heat supply load of the engine, allowing enhanced energy utilization. The thermal performance of the chemical heat pump in the cogeneration system is estimated based on the results of a packed-bed experiment. The estimation indicates that by storing the waste heat from the engine during low demand periods, the cogeneration system can produce more than several times the standard thermal output of the diesel engine during peak demand periods. Copyright © 2001 John Wiley & Sons, Ltd. [source]

A simulated auto-thermal membrane reformer process for a PEM fuel cell micro cogeneration unit

ASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 3 2009
Dr. Atilla Ersöz
Abstract There are several methods of producing hydrogen-rich gas from fossil resources such as natural gas or naphtha, for example, steam reforming, partial oxidation and auto-thermal reforming. In this paper, an integrated ATR membrane reactor system was simulated. The effect of operating parameters on the product distribution, fuel cell hydrogen utilization and the net electric efficiency of the overall system were discussed. The overall system was integrated with a 1-kWe PEM fuel cell. The ASPEN-HYSIS 3.2 software has been utilized for the simulations and calculations of the fuel processing reactions. Natural gas fuel has been used as feedstock and applied to the simulated flow-sheet model. It was desired to produce hydrogen-rich gas with a low CO formation using an autothermal membrane reformer. A very low CO content with higher content of hydrogen was provided by the membrane reformer, eliminating the use of the conventional preferential oxidation (PrOx) reactor. Different combinations of TATR, S/C, O2/C ratios and UH2 have been parametrically studied. Fuel processing efficiency and net electrical efficiency of all selected operating conditions have been calculated as well. Results indicate that the system parameters are very critical for the appropriate operation of the residential cogeneration system with ATR membrane unit. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source]

Membrane reformer PEM cogeneration systems for residential applications,Part A: full load and partial load simulation

ASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 3 2009
Stefano Campanari
Abstract This two-part paper investigates the performances and economic potential benefits of a fuel cell cogeneration system based on a membrane reformer (MREF), using polymer electrolyte membrane (PEM) fuel cells, applied to residential cogeneration. Part A of this work focuses on the thermodynamic analysis and simulation of the system at full and partial load conditions, discussing its performance by means of a sensitivity analysis carried out under different operating conditions. Part B presents the technoeconomic analysis of the proposed system integrated into a real residential application, dealing with the energy savings and the economic balances, and proposes a preliminary design of the cogeneration unit. The system is based upon a PEM fuel cell, integrated with a membrane reformer (MREF) to form a small-scale, highly efficient cogeneration unit, potentially suitable for application to distributed generation in the residential field. The high purity hydrogen fuel required by the PEM fuel cell is produced in the membrane reformer through hydrogen selective membranes based on a Pd-Ag alloy. The analysis is carried out aiming to define the system energy balances in all the conditions occurring under real operation, including the influence of ambient temperature and of the expected fuel cell efficiency decay with time. The discussion reveals the relevant potential advantages of the MREF solution with respect to fuel cell units based on steam reforming (SR) or auto-thermal reforming (ATR): when compared to these solutions, MREF exhibits a 10% points higher electrical efficiency and requires a much simpler plant layout. These results are the basis for the detailed system technoeconomic analysis carried out in Part B of the work. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source]

Membrane reformer PEM cogeneration systems for residential applications,Part B: techno-economic analysis and system layout

ASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 3 2009
Stefano Campanari
Abstract This two-part paper investigates the performances and potential economic benefits of a membrane reformer (MREF)-based fuel cell cogeneration system, using polymer electrolyte membrane (PEM) fuel cells, applied to residential cogeneration. Part A of the work focuses on the thermodynamic analysis and simulation of the system at full and partial load conditions, discussing its performance by means of a sensitivity analysis carried out under different operating conditions. Part B presents the techno-economic analysis of the proposed system integrated into a real residential application, dealing with the energy savings and the economic balances, and proposes a preliminary design of the cogeneration unit. The higher electric efficiency of the innovative MREF system proposed in this work allows a yearly cost savings about 50% higher than cost savings allowed by fuel cell cogeneration units based on conventional fuel processors. Moreover, CO2 emissions savings, calculated for an average northern Italy single-family load, is about 1.6 tCO2/year. The paper also presents a proposed system layout, discussing the preliminary design of all the required components and analyzing with particular care the issues related to the heat recovery loop and to the arrangement of the system key component: the membrane reforming reactor. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source]

An operational algorithm for residential cogeneration systems based on the monitored daily-basis energy demand

ELECTRICAL ENGINEERING IN JAPAN, Issue 2 2010
Yuka Yamagishi
Abstract Residential cogeneration systems with PEFC are promising as distributed power system resources with the ability to improve energy system efficiency. However, it is important to develop an efficient algorithm for operation because the energy demand at each house differs greatly from day to day. In this paper, we propose an operational algorithm and evaluate it from the viewpoint of energy conservation and economic effectiveness based on the energy demand characteristics. In the algorithm, the hot water and electricity demand on the next day are estimated based on the average of past data. The results of simulations using actually monitored energy demand data indicate that (1) the greater the electrical demand of a household, the more effective this algorithm becomes with respect to energy conservation; (2) the greater the hot water demand of a household, the more effective this algorithm becomes with respect to economic effectiveness. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 170(2): 37,45, 2010; Published online in Wiley InterScience (www.interscience.wiley. com). DOI 10.1002/eej.20892 [source]

Coordinated voltage control of transformer taps with provision for hierarchical structure in power system

ELECTRICAL ENGINEERING IN JAPAN, Issue 4 2009
Yoshiki Nakachi
Abstract Participation of distributed generators (DGs), such as wind turbines, cogeneration systems, etc., is a natural trend from an ecological point of view and will continue to increase. The outputs of these DGs mainly depend on weather conditions but do not correspond to the changes of electrical load demand necessarily. On the other hand, due to deregulation of the electric power market, the power flow in a power system will uncertainly vary with several power transactions. Thus, complex power flow by DGs or transactions will cause voltage deviation. It will be difficult to sustain the voltage quality by using conventional voltage/reactive power control in the near future. In this paper, in order to avoid such voltage deviation and to decrease the frequency of transformer tap operations, the coordinated voltage control scheme of transformer taps on account of hierarchical structure in the power system is proposed. In the proposed scheme, integral of voltage deviation at each layer bus is applied to decide the timing of each transformer tap operation. Numerical simulations confirm that the proposed scheme is able to respond to every condition on voltage deviation. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 166(4): 48,55, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20531 [source]

The evaluation of small cogeneration for residential heating

INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 13 2002
Kris R. Voorspools
Abstract The decision whether or not to install small cogeneration for residential purposes mainly depends on individual economic considerations, combined with ecological awareness. Since in most cases, the economic balance is still unfavourable, government grants are considered in order to bridge this economic barrier. It is however still unclear how these grants are best spent to obtain an optimal environmental benefit. In the case of cogeneration, mainly static and simplified methods are used, completely neglecting the dynamic interaction between the cogeneration systems and the central power system and the dynamic response of the cogeneration units themselves. In this paper, these issues are discussed in two parts. The first part clarifies how an actual cogeneration unit, if necessary in combination with a back-up boiler and heat storage, will respond to a certain demand. For this purpose, experiments were performed to establish the transient and stationary behaviour of the system. It is shown that the transient heating of the cogeneration engine is rather slow (e.g. half an hour after cold start, the engine only produced 65% of the heat it would have in stationary regime) where the electric transient behaviour is negligible. In the second part of the paper, dynamic simulations are performed to quantify the impact (primary energy saving and reduction in greenhouse-gas emissions) of the massive installation of cogeneration for residential heating. Two important parameters are isolated. First, the interaction with the expansion of the central power system is very important. If the installation of cogeneration prevents the commissioning of new power plants, the potential energy saving and (especially) emission reduction are reduced. The second parameter is the annual use of the cogeneration units. Here, the potential energy saving and emission reduction increase with increasing annual use. Copyright © 2002 John Wiley & Sons, Ltd. [source]