Papers by Keyword: Exergy

Abstract: The Efficiency of Energy and Exergy is Generally Used as the Mostimportant Parameter in Order to Introduce and Compare the Thermal Systems Offlat Plate Solar Collectors. the First Law of Thermodynamics is Not Solelycapable of Demonstrating Quantitative and Qualitative Performance of Suchsystems, so the Second Law is Required to Illustrate the Performances. in Thispaper, an Analysis was Done for Heat Transfer Performance and Exergy Efficiencyof Flat Plate Solar Collectors Using Four Types of Nanofluids, e.g. Zno/water,CeO₂/water, Nio and Coo/water. these Nanofluids were Used Withdifferent Nanoparticle Volume Fractions in the Range of 1% to 4%. Besides this,the Present Work also Focuses on the Performance of Solar Collector Withdifferent Volume Flow Rates. Investigation Consequences are also Compared Withthe Presently Available Literature for Conventional Solar Collectors. Thehighest Heat Transfer Performance and Exergy Efficiency were Obtained for CeO₂/waternanofluid among all Nanofluids. Nio/water and Coo/water Nanofluids Representalmost same Performance but Higher than Water. the Results Reveal that, CeO₂/waternanofluid Indicates Maximum Heat Transfer with Maximum Exergy.

Abstract: A computer analysis has been developed for studying the energy and exergy performance of an direct-injection, naturally-aspirated diesel engine operating under transient load or speed conditions. The model is validated at steady-state operation and incorporates many novel features for simulating the transient response and analyzing all of the engine availability terms. The analysis reveals via multiple diagrams how the exergy properties of the diesel-engine subsystems vary according to the engine cycles for various speed and load changes. The diagrams also show the current-speed response. In addition, the effects of operating parameters such as the intensity of the applied change or heat loss to the walls are described from first-and second-law.

Abstract: Exergy analysis is performed for transcritical Organic Rankine Cycle (ORC) with internal heat exchanger based on the second law of thermodynamics. Effects of source temperature as well as turbine inlet pressure (TIP) are investigated on the exergy destructions (or anergies) of the system as well as exergy efficiency. Results show that irreversibility of the system decreases with increasing TIP or decreasing source temperature. Exergy efficiency decreases with increasing source temperature; however has a maximum value with respect to TIP.

Abstract: The total exergy and exergy efficiencies have been calculated based on the energy utilization of Chinas railway transport from 2006 to 2010. The preliminary results indicate that: (1) the major fuels for China railway transport are diesel, coal and electricity; (2) The total exergy consumption is calculated as 491.59 PJ in 2006 and 480.19 PJ in 2010, which is approximately in accordance with Chinas economic growth rate. (3) With railway electrification and green technology being emerged in the transport system, the energy structure is considered upgrading gradually, e.g. more environment-friendly energy is used to be the alternative fuels. (4) The weighted mean of exergy efficiencies range from 26.41% to 26.62%, which are less than the conventional efficiency 28%, due to the irreversibility of exergy loss. In addition, both time and structural variation of the total exergy consumption and efficiency provides an insight to China's socio-economy, but also helps improve the national energy policies.

Abstract: A process of using LNG cold energy for ice-making was proposed, the process consisted of three parts: LNG vaporization system, the refrigerant circulation system and ice-making system. And LNG cold energy was delivered to ice-maker by refrigerant. Through design and optimization, the optimum temperature was confirmed in the ice-making process, the benefit of power saving was calculated, and the efficiency of energy utilization was analyzed by exergy analysis method. The research results showed that the average ice quantity was 1.59t/h with vaporization amount of 1000kg/h LNG. Taking ethylene glycol aqueous solution as refrigerant, when its temperature changed from-15°C to-6°C, the energy efficiency was higher with 18°C temperature difference. And the benefit of electricity saving was 112 kW and the efficiency of cold exergy was 5.52%. The process can be designed into skid-mounted, which can flexibly operate between different LNG vaporization stations.

Abstract: For the purpose of providing a scientific reference for improving energy conservation and performance of marine diesel engine, the thermal balance analysis and exergy balance analysis and emission research on ethanol diesel-oil alternative fuel of the existing diesel engine are performed. All necessary data are obtained from an actual diesel engine of KTA50-M2 which is used in a boat located in Dalian. The result shows that engine performance parameters are of no big change, however, the exhaust emissions are significantly reduced.

Abstract: Sustainable development as the leading civilization idea, and nanotechnology as the contemporary wave of technology significantly affecting the society, are brought together in this paper. A brief history of sustainability implementation from the start concept until European Construction Product Regulation is presented. The extended definitions of sustainable construction and sustainable material are analysed with adequate conclusions towards Concrete. The category of Exergy is implemented as a measure for “natural environmentally-friendly” meaning. The generalised concrete development curve is presented with discussion of Well Defined Concrete Performance. The statement that the sustainability is necessity for concrete and the nanotechnology is the chance for the future of concrete polymer composite is the final conclusion of the paper.

Abstract: Pipeline transportation is a substance conveying process that makes crude oil flowing from first station to ultimate station and at the same time takes a certain amount of driving energy for cost. Based on related theories of engineering fluid mechanics, mathematics analytic formula of driving exergy in oil pipeline transportation is deduced by micro-element analysis. We can get the conclusion that driving exergy loss has a positive correlation with diameter and throughput, and also a contrary trend with insulation thickness and outbound temperature by analyzing the influence on driving exergy loss from operation parameters in pipeline process,. This research can provide theoretical guidance for energy consumption classification, and further more, the technical support for energy consumption in pipeline system.

Abstract: In this paper, the experimental data of CO, CO₂ and total volatile organic compound (TVOC) concentration in a residential kitchen are presented. Based on them, a simulation software with friendly and simply operating interfaceis is developed on the platform of VC++. The distribution law of the contaminants is studied via the simulation results, and it is obvious that location of accumulation of the contaminants are highly relevant to the location of stove and closer to the walls. An addition natural air makeup system is proposed to improve indoor airenvironment in kitchens, the effection of the air makeup system is analyzed with exergy theory.

Abstract: Organic Rankine Cycle (ORC) has attracted much attention in recent years, since it has potential of reducing fossil fuel consumption and many favorable characteristics to exploit low-grade energy sources. This work carries out an exergetical performance assessment of ORC with superheating comparatively for various organic fluids. Special attention is paid to the effect of evaporating temperature on the exergy destructions (anergies) at various system components and the exergy efficiency of system. Results show that for a given source both the anergies at the components and exergy efficiency may have a peak value or monotonically increase with evaporating temperature.