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Shuqing GUO~ Yunhan XIAO~ Wendong TIAN~ Zhedian ZHANG~.Zhongyuan University of Technology Zhengzhou City Henan Province China.Institute of Engineering Thermophysics Chinese Academy of Sciences Beijing China Associate Professor 《热科学学报(英文版)》2006,15(3):274-280
This paper considers the combination of hydrothermal degradation(HTD)and superheated steam(SHS)drying indisposal and processing of degradable organic wastes in municipal solid wastes(MSW).In SHS drying, a fractionof dryer thermal energy input can be recovered and used to satisfy the heat requirement in maintaining the HTDoperating temperature.Both energy and exergy analysis are applied to the combined process.The analysis coversranges of dryer inlet temperatures of 202.38-234.19℃ and feed water content of 32.5-65%.Thermal energyanalysis shows that the combination of HTD and SHS drying can achieve thermal energy self-sufficiency(TES)by manipulating process variables.The exergy analysis indicates the location,type,and magnitude of the exergylosses during the whole process by applying the second law of thermodynamics. 相似文献
2.
供暖锅炉系统的火用分析与技术节能 总被引：1，自引：0，他引：1
本文用火用分析的方法分析了影响供暖锅炉系统燃烧过程、传热过程、排烟和辅助动力设备火用损失的主要因素及程度大小 ,并在此基础上提出了供暖锅炉系统技术节能的方向和措施。 相似文献
3.
注汽锅炉系统用能分析及改进建议 总被引：1，自引：0，他引：1
建立了注汽锅炉系统及设备的能理平衡分析及火用分析模型,给出了评价准则及计算公式。根据测试数据对一在用的注汽锅炉系统进行了分析计算,给出了主要计算结果。本文完善了注汽锅炉的热力学分析方法,这为全面分析注汽锅炉的用能特性,提供了依据。 相似文献
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This study deals with an energy and exergy analysis of Salihli geothermal district heating system (SGDHS) in Manisa, Turkey. In the analysis, actual system data are used to assess the district heating system performance, energy and exergy efficiencies, specific exergy index, exergetic improvement potential and exergy losses. Energy and exergy losses throughout the SGDHS are quantified and illustrated in the flow diagram. The exergy losses in the system, particularly due to the fluid flow, take place in the pumps and the heat exchanger, as well as the exergy losses of the thermal water (e.g. geothermal fluid) and the natural direct discharge of the system. As a result, the total exergy losses account for 2.22, 17.88 and 20.44%, respectively, of the total exergy input to the entire SGDHS. The overall energy and exergy efficiencies of the SGDHS components are also studied to evaluate their individual performances and determined to be 55.5 and 59.4%, respectively. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
5.
研究了蒸汽系统的能效评估方法。首先以热力学第一、第二定律为依据建立了蒸汽系统能效评估体系,其次根据能量平衡和质量平衡的原理进行了蒸汽系统建模,最后给出了能效指标的计算方法并使用Visual studio 2008开发了蒸汽系统能效评估软件。结果分析表明本软件能够较为准确地建立蒸汽系统的模型并计算出能效指标,对蒸汽系统节能评估工作具有较高的实用价值。 相似文献
6.
低温热水地板辐射采暖的(火用)分析 总被引：1，自引：0，他引：1
本文建立了采暖系统的分析模型 ,利用所建立的模型 ,对地板辐射采暖和传统的散热器采暖两种采暖方式进行了分析。结果表明 ,当地板辐射采暖的供回水温度为 4 5℃ 35℃时 ,与传统的散热器采暖相比 ,其效率大约高 18% ,地板辐射采暖所需供水温度低 ,可以充分利用各种低温热源及工业废热等低品位能量 ,是一种具有发展潜力的节能型采暖方式 相似文献
7.
从的基本概念出发 ,阐述了物理和化学的计算方法 ,推导了热力学中常见热力过程的变量表达式 ,为工程分析提供了理论计算基础 相似文献
8.
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. 相似文献
9.
办公室和厂房供暖常采用蒸汽供暖或热水供暖。结合实际情况分析比较了两种供暖方式的优缺点。蒸汽供暖一次性投入较小,但使用维护费用较大;热水供暖和蒸汽供暖相比需增设一套热水循环装置、回水池和回水管路,但运行费用相对较少,且可最大程度地减少跑、冒、滴、漏现象的发生,从而可大大提高设备和材料的利用率,降低成本,最终起到节能降耗的作用,应广泛推广和应用。 相似文献
10.
The objective of this paper is to perform the energy, exergy and exergoeconomic analysis for the Hamedan steam power plant. In the first part of the paper, the exergy destruction and exergy loss of each component of this power plant is estimated. Moreover, the effects of the load variations and ambient temperature are calculated in order to obtain a good insight into this analysis. The exergy efficiencies of the boiler, turbine, pump, heaters and the condenser are estimated at different ambient temperatures. The results show that energy losses have mainly occurred in the condenser where 306.9 MW is lost to the environment while only 67.63 MW has been lost from the boiler. Nevertheless, the irreversibility rate of the boiler is higher than the irreversibility rates of the other components. It is due to the fact that the combustion reaction and its high temperature are the most significant sources of exergy destruction in the boiler system, which can be reduced by preheating the combustion air and reducing the air–fuel ratio. When the ambient temperature is increased from 5 to 24°C, the irreversibility rate of the boiler, turbine, feed water heaters, pumps and the total irreversibility rate of the plant are increased. In addition, as the load varies from 125 to 250 MW (i.e. full load) the exergy efficiency of the boiler and turbine, condenser and heaters are increased due to the fact that the power plant is designed for the full load. In the second part of the paper, the exergoeconomic analysis is done for each component of the power plant in order to calculate the cost of exergy destruction. The results show that the boiler has the highest cost of exergy destruction. In addition, an optimization procedure is developed for that power plant. The results show that by considering the decision variables, the cost of exergy destruction and purchase can be decreased by almost 17.11%. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
11.
Steam cooking is beneficial over other cooking techniques like boiling since it preserves more vitamins lost during other methods. In this study, a novel solar food steamer (SFS) based on a parabolic dish concentrator (PDC) is designed and constructed for domestic food preparation. A straightforward fabrication process of a 2.626 m2 PDC with design calculations is also presented. The system's instantaneous energy and exergy efficiency evaluation has been examined from different tests over three consecutive days. The system's high energetic and exergetic efficiency was achieved in the case of sweet potato, that is, 72.83% and 15.14%, respectively. In the case of dried chickpeas, the maximum steaming duration of 70 min was attained, along with an energy efficiency of 47.74% and an exergy efficiency of 10.07%. In addition, an economic analysis was performed to determine the payback time in terms of cost and utility. The payback time for the proposed method is 2.4 years. The SFS may save 43 kg/month of carbon dioxide from escaping into the atmosphere; it can be considered an environmentally valuable device. 相似文献
12.
Mehmet Karakilcik Mustafa Erden Müzeyyen Cilogulları Ibrahim Dincer 《International Journal of Hydrogen Energy》2018,43(23):10549-10554
In this study, the hydrogen production performance of a reactor assisted by a solar pond by photoelectrochemical method is examined conceptually. The main components of the new integrated system are a solar pond, a photovoltaic panel (PV) and a hybrid chlor-alkali reactor which consists of a semiconductor anot, photocathode and cation exchange membrane. The proposed system produces hydrogen via water splitting reaction and also yields the by products namely chlorine and sodium hydroxide while consumes saturated NaCl solution and pure water. In order to increase the efficiency of the reactor, the saturated hot NaCl solution at the heat storage zone (HSZ) of the solar pond is transferred to the anot section and the heated pure water by heat exchanger in the HSZ is transferred to cathode section. The photoelectrode releases electrons for hydrogen production with diminishing the power requirement from the PV panel that is used as a source of electrical energy for the electrolysis. The results confirm that the thermal performance of the solar pond plays a key role on the hydrogen production efficiency of the reactor. 相似文献
13.
Exergoeconomic formulations and procedure including exergy flows and cost formation and allocation within a high temperature steam electrolysis (HTSE) system are developed, and applied at three environmental temperatures. The cost accounting procedure is based on the specific exergy costing (SPECO) methodology. Exergy based cost-balance equations are obtained by fuel and product approach. Cost allocations in the system are obtained and effect of the second-law efficiency on exergetic cost parameters is investigated. The capital investment cost, the operating and maintenance costs and the total cost of the system are determined to be 422.2, 2.04, and 424.3 €/kWh, respectively. The specific unit exergetic costs of the power input to the system are 0.0895, 0.0702, and 0.0645 €/kWh at the environmental temperatures of 25 °C, 11 °C, and −1 °C, respectively. The exergetic costs of steam are 0.000509, 0.000544, and 0.000574 €/kWh at the same environmental temperatures, respectively. The amount of energy consumption for the production of one kg hydrogen is obtained as 133 kWh (112.5 kWh power + 20.5 kWh steam), and this corresponds to a hydrogen cost of 1.6 €/kg H2. 相似文献
14.
This study deals with the energetic and exergetic performance assessment of a combined heat and power system with micro gas turbine (MGTCHP). Quantitative energy and exergy balance for each component and the whole MGTCHP system was considered, while energy and exergy consumption within the system were determined. The performance characteristics of this MGTCHP system were evaluated using energy and exergy analyses methods. The energetic and exergetic efficiencies of the MGTCHP system are calculated as 75.99% with 254.55 kW (as 99.15 kW—electrical and 155.40 kW—hot water@363.15 K) and 35.80% with 123.61 kW (as 99.15 kW—electrical and 24.46 kW—hot water@363.15 K), respectively. The maximum energy loss and exergy consumption occur at 44.03 kW in the stack gas and 129.61 kW in the combustion chamber, respectively. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
15.
This paper presents the energy and exergy analyses of sugar production stages by using the operational data from Bor Sugar Plant, Turkey. For these purposes, all stages of sugar production, considered as a steady-state open thermodynamic system, were analysed by employing the first and second law of thermodynamics. In this regard, the first and second law efficiencies, the magnitude and place of exergy losses in these production stages were estimated and discussed in detail. It was concluded that the exergy loses took place mostly during the sherbet production process (ηI,sp=96.8% ηII,sp=49.3%) because of the irreversibility in the sub-operation stages, which are vapour production, circulation sherbet mixing and bagasse compression. Therefore, it is generally suggested that the irreversibility, mostly stem from the finite temperature differences at the production stages, should be reduced to conduct more productively the sugar production process. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
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The effect of sensible heating of the phase-change material (PCM) before melting and subcooling after solidification, on the performance of the latent heat storage system (LHSS), is studied in terms of first- and second-law efficiencies for the overall charge–discharge cycle. The external heat transfer irreversibilities on account of the interaction between the heat transfer fluid and the storage element are characterized and the optimum phase-change temperature for maximum second-law efficiency is studied. The performance of the LHSS operation is assessed with and without sensible heating before melting and subcooling after solidification. It is observed that the optimum phase-change temperature is higher, and, the overall second-law efficiency is greater for LHSS with sensible heating and subcooling beyond a certain phase-change temperature compared to latent heat storage alone. In addition, the first-law overall efficiency is found to exhibit a minimum and a pre-heated discharge stream is shown to result in a substantial improvement of the second-law efficiency. © 1998 John Wiley & Sons, Ltd. 相似文献
18.
In this study, a thermodynamic analysis of a Rankine cycle reheat steam power plant is conducted, in terms of the first law of thermodynamic analysis (i.e. energy analysis) and the second law analysis (i.e. exergy analysis), using a spreadsheet calculation technique. The energy and exergy efficiencies are studied as 120 cases for different system parameters such as boiler temperature, boiler pressure, mass fraction ratio and work output. The temperature and pressure values are selected in the range between 400 and 590°C, and 10 and 15 MPa, being consistent with the actual values. The calculated energy and exergy efficiencies are compared with the actual data and the literature work, and good agreement is found. The possibilities to further improve the plant efficiency and hence reduce the inefficiencies are identified and exploited. The results show how exergy analysis can help to make optimum design decisions in a logical manner. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
19.
Exergoeconomic Based Optimization of a Gas Fired Steam Power Plant Using Genetic Algorithm 
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下载免费PDF全文 This research paper mainly deals with exergy, economic, and environmental investigation of a 250 MW steam power plant located in Iran. In order to model this power plant, energy balance equations are used and each part of the power plant is modeled accordingly. Further by introducing the boiler as the main source of irreversibility, two approaches are presented to improve the boiler performance, reduction of excess air, and temperature reduction of gasses leaving the stacks. To study the effect of these two approaches, an objective function including the cost rate of exergy destruction of boiler, fuel cost, and cost rate of environmental impact is presented. The optimization process is done using a genetic algorithm. It is concluded that by optimizing, 20% reduction in the overall cost rate and 88% reduction in the cost rate of environmental impact can be achieved. 相似文献
20.
This study deals with an exergetic performance evaluation of a geothermally heated building. This building used in the analysis has a volume of 1147.03 m3 and a net floor area of 95.59 m2, while indoor and exterior air temperatures are 20 and 0 °C, respectively. The geothermal heating system used for the heat production was constructed in the Ozkilcik heating center, Izmir, Turkey. Thermal water has a pressure of 6.8 bar, a temperature of 122 °C and a mass flow rate of 54.73 kg/s, while it is reinjected at 3.2 bar and 72 °C. The system investigated feeds three regions. Among these, the Ozkanlar region has supply/return pressure and temperature values of 4.6/3 bar and 80/60 °C, respectively. Energy and exergy flows are studied to quantify and illustrate exergy destructions in the overall system. Total exergy input rate to the system is found to be 9.92 kW and the largest exergy destruction rate occurs in the primary energy transformation at 3.85 kW. 相似文献