scholarly journals ANÁLISE DA EFICIÊNCIA EXERGÉTICA DE RECIFE / ANALYSIS OF EXERGETIC EFFICIENCY OF RECIFE

2021 ◽  
Vol 3 (3) ◽  
Author(s):  
Pedro Vitor Silva ◽  
Rafael Figueredo
Keyword(s):  
Exergetic Efficiency

O presente trabalho discorre aspectos relacionados à eficiência exergética da cidade de Recife a partir de dados de consumo de combustíveis automobilísticos, gás liquefeito de petróleo e energia elétrica. Dada uma breve introdução sobre os principais aspectos da cidade em questão, observa-se o funcionamento econômico da região voltado ao setor de serviços, o que justifica as proporções de exergia de entrada sendo a gasolina e a energia elétrica os principais vetores exergéticos. Realizada análise da exergia destruída tem-se que a eficiência exergética da cidade é de 22,58%. A partir dos dados de consumo de combustível foi possível estimar as emissões de dióxido de carbono na cidade de Recife, as quais se encontram a aproximadamente 1,5MtCO2 por ano. Espera-se que os resultados encontrados neste artigo sirvam como referência para futuros trabalhos nesta área para que seja possível comparar as cidades quanto sua eficiência exergética e, assim, fomentar pesquisas que tenham como foco a termodinâmica das cidades.

scholarly journals Energy and Exergy Analysis of a Plane Reflector Integrated Photovoltaic-Thermal Water Heating System

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Prem Sagar Naik ◽  
Arun Palatel
Keyword(s):  
Solar Radiation ◽  
Thermal Water ◽  
Winter Season ◽  
Performance Testing ◽  
Electrical Energy ◽  
Heating System ◽  
Present System ◽  
Exergetic Efficiency ◽  
Water Heating ◽  
Electrical Output

A photovoltaic-thermal water heating system is a hybrid energy conversion device transforming the incident solar radiation to yield electrical energy and thermal energy. Plane reflectors are found to be a convenient option for enhancing the solar radiation incident on the collector plane. The present work investigates the performance of a photovoltaic-thermal water heater integrated with a plane reflector mounted on the top edge of the collector for the tropical climate of Calicut (11.25°N, 75.78°E). Performance testing of the system has been carried out for the winter season of the location. The variations in thermal and electrical output are studied for various inclination angles of the reflector. The system performance is evaluated on the basis of system energy efficiency and exergetic efficiency. It is observed that there is a significant enhancement in the thermal and electrical output of the system with the integration of the reflector as compared to the system without the reflector. For the present system, the reflector tilt angle in the range of 85–100° has been found to be suitable in terms of enhanced system output and exergetic efficiency for the winter conditions of Calicut.

Selection of a Waste Heat Recovery System for a Marine Diesel Engine Based on Exergy Analysis

2016 ◽  
Vol 25 ◽  
pp. 36-51
Author(s):  
Salman Abdu ◽  
Song Zhou ◽  
Malachy Orji
Keyword(s):  
Diesel Engine ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Marine Diesel Engine ◽  
Exergetic Efficiency ◽  
Waste Heat Recovery System ◽  
Recovery System ◽  
Heat Recovery System ◽  
Marine Diesel

Highly increased fuel prices and the need for greenhouse emissions reduction from diesel engines used in marine engines in compliance with International Maritime Organization (IMO) on the strict regulations and guidelines for the Energy Efficiency Design Index (EEDI) make diesel engine exhaust gas heat recovery technologies attractive. The recovery and utilization of waste heat not only conserves fuel, but also reduces the amount of waste heat and greenhouse gases dumped to the environment .The present paper deals with the use of exergy as an efficient tool to measure the quantity and quality of energy extracted from waste heat exhaust gases in a marine diesel engine. This analysis is utilized to identify the sources of losses in useful energy within the components of the system for three different configurations of waste heat recovery system considered. The second law efficiency and the exergy destroyed of the components are investigated to show the performance of the system in order to select the most efficient waste heat recovery system. The effects of ambient temperature are also investigated in order to see how the system performance changes with the change of ambient temperature. The results of the analysis show that in all of the three different cases the boiler is the main source of exergy destruction and the site of dominant irreversibility in the whole system it accounts alone for (31-52%) of losses in the system followed by steam turbine and gas turbine each accounting for 13.5-27.5% and 5.5-15% respectively. Case 1 waste heat recovery system has the highest exergetic efficiency and case 3 has the least exergetic efficiency.

Simulation and Optimization of Combined Cycle Power Cycles Through HRSG’s Heat Exchangers Arrangement and Parameters for Exergy and Cost

2012 ◽  
Author(s):  
Ravin G. Naik ◽  
Chirayu M. Shah ◽  
Arvind S. Mohite
Keyword(s):  
Power Plant ◽  
Steam Generator ◽  
Heat Exchangers ◽  
Heat Recovery ◽  
Second Law Of Thermodynamics ◽  
Combined Cycle ◽  
Heat Recovery Steam Generator ◽  
Exergetic Efficiency ◽  
Power Cycles ◽  
Combined Cycle Power Plant

To produce the power with higher overall efficiency and reasonable cost is ultimate aim for the power industries in the power deficient scenario. Though combined cycle power plant is most efficient way to produce the power in today’s world, rapidly increasing fuel prices motivates to define a strategy for cost-effective optimization of this system. The heat recovery steam generator is one of the equipment which is custom made for combined cycle power plant. So, here the particular interest is to optimize the combined power cycle performance through optimum design of heat recovery steam generator. The case of combined cycle power plant re-powered from the existing Rankine cycle based power plant is considered to be simulated and optimized. Various possible configuration and arrangements for heat recovery steam generator has been examined to produce the steam for steam turbine. Arrangement of heat exchangers of heat recovery steam generator is optimized for bottoming cycle’s power through what-if analysis. Steady state model has been developed using heat and mass balance equations for various subsystems to simulate the performance of combined power cycles. To evaluate the performance of combined power cycles and its subsystems in the view of second law of thermodynamics, exergy analysis has been performed and exergetic efficiency has been determined. Exergy concepts provide the deep insight into the losses through subsystems and actual performance. If the sole objective of optimization of heat recovery steam generator is to increase the exergetic efficiency or minimizing the exergy losses then it leads to the very high cost of power which is not acceptable. The exergo-economic analysis has been carried to find the cost flow from each subsystem involved to the combined power cycles. Thus the second law of thermodynamics combined with economics represents a very powerful tool for the systematic study and optimization of combined power cycles. Optimization studies have been carried out to evaluate the values of decision parameters of heat recovery steam generator for optimum exergetic efficiency and product cost. Genetic algorithm has been utilized for multi-objective optimization of this complex and nonlinear system. Pareto fronts generated by this study represent the set of best solutions and thus providing a support to the decision-making.

scholarly journals Outdoor performance analysis of a monocrystalline photovoltaic module: Irradiance and temperature effect on exergetic efficiency

2015 ◽  
Vol 10 (11) ◽  
pp. 351-358 ◽  
Author(s):  
El Banany ELHADJ SIDI Cheikh ◽  
Lamine NDIAYE Mamadou ◽  
NDIAYE Ababacar ◽  
Alioune NDIAYE Papa
Keyword(s):  
Performance Analysis ◽  
Temperature Effect ◽  
Photovoltaic Module ◽  
Exergetic Efficiency

scholarly journals ANALISA ENERGI DAN EKSERGI PADA PENGERINGAN TEPUNG TAPIOKA MENGGUNAKAN PENGERING KONTINYU UNGGUN FLUIDISASI GETAR

REAKTOR ◽  
2016 ◽  
Vol 16 (1) ◽  
pp. 24 ◽  
Author(s):  
Suherman Suherman ◽  
Rona Trisnaningtyas
Keyword(s):  
Energy Efficiency ◽  
Fluidized Bed ◽  
Exergy Analysis ◽  
Cassava Starch ◽  
Energy Utilization ◽  
Exergetic Efficiency ◽  
Energy And Exergy ◽  
Vibrated Fluidized Bed ◽  
Energy And Exergy Analysis ◽  
Utilization Ratio

Energy and exergy analysis of cassava starch drying in continuous vibrated fluidized bed dryer were carried out to assess the performance of the system in terms of energy utilization ratio, energy efficiency, exergy inflow and outflow, exergy loss, and exergetic efficiency. The results showed cassava starch has starch content 87%, degree of whiteness 95%, negative fiber content, sperichal granula with average diameter12.32 μm, orthorhombic crystal structure and crystal size 47.467 nm . Energy utilization and energy utilization ratio increased from 0.08 to 0.20 J/s and 0.35 to 0.4 as the drying temperature  increased from 50 to 70 oC. Energy efficiency increased from 13.80 % to 23.31 %, while exergy inflow, outflow, and losses increased from 4.701 to 14.678, 2.277 to 6.344, and 2.424 to 8.334 J/s respectively in the above temperature range. Exergetic efficiency decreased with increase in drying air temperature, while exergetic improvement potential increased with increased drying air temperature. Keywords: Cassava starch, continuous drying, energy and exergy analysis, vibrated fluidized bed Abstrak Analisis energi dan eksergi pengeringan pati tapioka menggunakan pengering kontinu unggun fluidisasi getar, telah dilakukan untuk menilai kinerja sistem dalam bentuk utilisasi energi, efisiensi energi, eksergi masuk dan keluar, eksergi hilang dan efisiensi eksergi. Hasil analisis pati memiliki kandungan starch 87%, tingkat keputihan 95%, kandungan serat negatif, bentuk partikel granular spherical dengan diameter 12,32 μm, struktur kristal orthorhombic dan ukuran kristal sebesar 47,467 nm. Peningkatan suhu pengering dari 50 menjadi 70 0C akan meningkatkan utilisasi energi dan rasio utilisasi energi dari 0,08 menjadi 0,20 J/s dan 0,35 menjadi 0,4. Efisiensi energi meningkat dari 13,80% hingga 23,31%, sedangkan eksergi masuk dan keluar, eksergi hilang meningkat dari 4,701 menjadi 14,678, 2,277 menjadi 6,344, dan 2,424 menjadi 8,334 J/s. Efisiensi eksergi menurun dengan naiknya suhu sedangkan potensi pengembangan eksergi meningkat dengan naiknya suhu. Kata kunci:. Analisis energi dan eksergi, pati tapioka, pengeringan kontinu, unggun fluidisasi getar

Investigation Into Optimal Operation of BCHP Systems in the Air-Conditioning Season

2006 ◽  
Author(s):  
Jiacong Cao ◽  
Hong Fang
Keyword(s):  
Power Generation ◽  
Energy Conservation ◽  
Performance Optimization ◽  
Optimization Problems ◽  
Economic Effect ◽  
Numerical Data ◽  
Computer Time ◽  
Optimal Operation ◽  
Exergetic Efficiency ◽  
Lower Efficiency

Building cooling, heating and power generation (BCHP) is important for the sustainable energy strategy in China because of its contribution to energy conservation and the reduction of CO2 emissions. The number of BCHP or small-scaled combined cooling, heating and power generation systems that have been put to use or are in the course of construction is steadily increasing in China. However, in many cases the performance of BCHP systems is not good enough, i.e., the average real exergetic efficiency of whole system is much lower than expected and the economic effect is not satisfactory. This is a problem that perplexes designers and plant owners and need be investigated so as to increase the knowledge of optimizing the operation of BCHP systems. In this paper the performance of a typical BCHP system is investigated using thermodynamic and thermoeconomic analyses based on the simulating results of off-design operation and the solution of performance optimization of the system. With the help of a great number of real running data of the system and the master data supplied by manufacturers, a model of the system operation is developed to simulate the whole domain of operation on off-design conditions. In order to shorten computer time the operation domain is described by a set of functions obtained by curve fitting using the numerical data from the simulation. Two models of optimization, of which the objective functions are the exergetic efficiency and gross benefit of the whole BCHP system separately, are established in virtue of these fitted functions. The simulation of off-design operation and the solution of the optimization problems supply a great number of useful data that form various graphs, which are to be the references to energy conservation and economic operation of the systems. The investigation indicates that there are some differences between the optimum working conditions obtained by the two optimization models, whereas it is inevitable that the system runs with some lower efficiency and less gross benefit when working at high cooling or heating load factors. By analyzing the data some significant conclusions are obtained, which will be helpful for the BCHP industry in China.

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