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Heat Demand (heat + demand)
Selected AbstractsProposal and evaluation of a gas engine and gas turbine hybrid cogeneration system in which cascaded heat is highly utilizedELECTRICAL ENGINEERING IN JAPAN, Issue 3 2009Pyong 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] Potential of biomass-fired combined heat and power plants considering the spatial distribution of biomass supply and heat demandINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 11 2010Johannes Schmidt Abstract Combined heat and power (CHP) plants fired by forest wood can significantly contribute to attaining the target of increasing the share of renewable energy production. However, the spatial distribution of biomass supply and of heat demand limits the potentials of CHP production. This article assesses CHP potentials using a mixed integer programming model that optimizes locations of bioenergy plants. Investment costs of district heating infrastructure are modeled as a function of heat demand densities, which can differ substantially. Gasification of biomass in a combined cycle process is assumed as production technology. Some model parameters have a broad range according to a literature review. Monte-Carlo simulations have therefore been performed to account for model parameter uncertainty in our analysis. The model is applied to assess CHP potentials in Austria. Optimal locations of plants are clustered around big cities in the east of the country. At current power prices, biomass-based CHP production allows producing around 3% of the total energy demand in Austria. Yet, the heat utilization decreases when CHP production increases due to limited heat demand that is suitable for district heating. Production potentials are most sensitive to biomass costs and power prices. Copyright © 2009 John Wiley & Sons, Ltd. [source] Modeling an industrial energy system: Perspectives on regional heat cooperationINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 9 2008S. Klugman Abstract Through energy efficiency measures, it is possible to reduce heat surplus in the pulp and paper industry. Yet pulp and paper mills situated in countries with a heat demand for residential and commercial buildings for the major part of the year are potential heat suppliers. However, striving to utilize the heat within the mills for efficient energy use could conflict with the delivery of excess heat to a district heating system. As part of a project to optimize a regional energy system, a sulfate pulp mill situated in central Sweden is analyzed, focusing on providing heat and electricity to the mill and its surrounding energy systems. An energy system optimization method based on mixed integer linear programming is used for studying energy system measures on an aggregated level. An extended system, where the mill is integrated in a regional heat market (HM), is evaluated in parallel with the present system. The use of either hot sewage or a heat pump for heat deliveries is analyzed along with process integration measures. The benefits of adding a condensing unit to the back-pressure steam turbine are also investigated. The results show that the use of hot sewage or a heat pump for heat deliveries is beneficial only in combination with extended heat deliveries to an HM. Process integration measures are beneficial and even increase the benefit of selling more heat for district heating. Adding a condensing turbine unit is most beneficial in combination with extended heat deliveries and process integration. Copyright © 2007 John Wiley & Sons, Ltd. [source] Modelling and optimization of district heating and industrial energy system,an approach to a locally deregulated heat marketINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 5 2004Alemayehu Gebremedhin Abstract Regions with densely concentration of industries and district heating systems (DHS) could be interesting study object from the light of an integrated heat market on local basis. System analysis with a widened system boundary could be used as an approach to evaluate the benefit of an integrated heat supply system. In this study, an energy system model consisting of totally seven different participants is designed and the optimization results of the system analysis are presented. With applied data and assumptions, the study shows that a significant amount of the heat demand within two sub-systems can be covered by heat supply from the heat market (the entire heat comes from two industries). Shadow prices, which can be used for heat pricing, indicate the advantage of an integrated system. The system cost reduction through integration and the availability of several actors with diverse energy supply system, makes the region under study an interesting area to prove a locally deregulated heat market. Copyright © 2004 John Wiley & Sons, Ltd. [source] Ranking factors of an investment in cogeneration: Sensitivity analysis ranking the technical and economical factorsINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 3 2001Gunnel Sundberg Abstract A deregulation of the electricity market in Europe will result in increased competition among the power-producing companies. They will therefore carefully estimate the financial risk in an investment in new power-producing capability. One part of the risk assessment is to perform a sensitivity analysis. This paper presents a sensitivity analysis using factorial design, resulting in an assessment of the most important technical and economical factors affecting an investment in a gas turbine combined cycle and a steam cycle fired by woodchips. The study is performed using a simulation model that optimizes the operation of existing power plants and potential new investments to fulfil the desired heat demand. The local utility system analysed is a Swedish district heating system with 655 GWh y,1 heat demand. The conclusion is that to understand which of the technical and economical factors affect the investment, it is not sufficient to investigate the parameters of the studied plant, but also the parameters related to the competing plants. Both the individual effects of the factors and the effect of their interaction should be investigated. For the energy system studied the price of natural gas, price of woodchips and investment cost have the major influence on the profitability of the investment. Copyright © 2001 John Wiley & Sons, Ltd. [source] A matrix method for multicomponent distillation sequencesAICHE JOURNAL, Issue 7 2010Vishesh H. Shah Abstract We describe a simple-to-use "matrix" method for obtaining all the basic distillation configurations and additional thermally coupled configurations that separate a zeotropic multicomponent feed into essentially pure product streams. This provides an opportunity to rank-list the configurations for a given application subject to criteria of interest. The only information needed to generate the configurations is the number of components in the feed. We have successfully enumerated all the configurations for feeds containing up to eight components. The method can also be used to generate nondistillation and hybrid separation configurations, and even easy-to-retrofit configurations. We illustrate the use of this method by applying it to the highly energy-intensive problem of petroleum crude distillation. We have identified more than 70 new configurations that could potentially have lower heat duty than the existing configuration. A significant number of these could reduce the heat demand by nearly 50%. © 2009 American Institute of Chemical Engineers AIChE J, 56: 1759,1775, 2010 [source] PV thermal systems: PV panels supplying renewable electricity and heatPROGRESS IN PHOTOVOLTAICS: RESEARCH & APPLICATIONS, Issue 6 2004Dr. Wim G. J. van Helden Abstract With PV Thermal panels sunlight is converted into electricity and heat simultaneously. Per unit area the total efficiency of a PVT panel is higher than the sum of the efficiencies of separate PV panels and solar thermal collectors. During the last 20 years research into PVT techniques and concepts has been widespread, but rather scattered. This reflects the number of possible PVT concepts and the accompanying research and development problems, for which it is the general goal to optimise both electrical and thermal efficiency of a device simultaneously. The aspects that can be optimised are, amongst others, the spectral characteristics of the PV cell, its solar absorption and the internal heat transfer between cells and heat-collecting system. Another important level of optimisation is for the PVT device geometry and the integration into a system. The electricity and heat demand and the temperature level of the heat determine the choice for a certain system set-up. With an optimal design, PVT systems can supply buildings with 100% renewable electricity and heat in a more cost-effective manner than separate PV and solar thermal systems and thus contribute to the long-term international targets on implementation of renewable energy in the built environment. Copyright © 2004 John Wiley & Sons, Ltd. [source] Single, twin and triple buried heating pipes: on potential savings in heat losses and costsINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 14 2005Benny Bøhm Abstract In order to make district heating systems competitive in areas with single family houses or in other areas with low heat demands it is necessary to reduce the heat losses from the pipes. In recent years the twin pipe has become popular in the Nordic countries. In the article we describe how the heat loss and the heat loss coefficients can be calculated. We introduce the triple pipe with three media pipes (two supply pipes and one return pipe). The temperature dependency and the ageing of polyurethane insulation are briefly discussed. A comparison is made for different 80 mm distribution pipes and for different service pipes with respect to heat losses and to resources, i.e. materials needed for the casing and polyurethane insulation and the gravel in the excavations. For the distribution pipe we found that an egg-shaped twin pipe can reduce the heat loss by 37% and the investments by 12% compared with a pair of single pipes. For the service pipes we found that the triple pipe reduces the heat loss by 45% compared with a common pair of single pipes and by 24% compared with circular twin pipes. The reduction in investment index is 21%. The article also addresses the question of the heat exchange between the two media pipes in a twin pipe. Copyright © 2005 John Wiley & Sons, Ltd. [source] | ||||||||||