Experimental Performance Analysis of R1234yf in an Air-Conditioning System as Substitute of R134a

In this work, R1234yf is tested in an air-conditioning system as a proposed alternative to R134a. The system is tested at 30, 35, 40, 45 and 50[Formula: see text]Hz evaporator fan frequency to cool the air entering into the evaporator section at a fixed temperature of 35∘C. The system is charged with 600, 700, 800, 1000 and 1200[Formula: see text]g of each refrigerant. The charge mass of 800 grams gives the best performance for both refrigerants. Also, R1234yf has higher COP, exergetic efficiency, second law efficiency, and lower compressor power consumption. Both refrigerants operate at a moderate range of compressor discharge temperature of 85∘C.

Energy, Exergy and Economic Analysis of Absorption Chiller Systems: A Case Study for a Wood Pencil Factory

This study examines the use of absorption chiller systems in a designated industrial facility having waste heat by conducting energy, exergy and economic analyses. The absorption chiller systems namely single-effect, double-effect series, double-effect parallel and double-effect reverse parallel were analysed to determine the best alternative for the wood pencil factory. The results indicated that the COP of the single-effect absorption chiller systems is changed from 0.758 to 0.763 when the temperature of the generator was increased from 89 ºC to 125 ºC. However, the exergetic performance of the single-effect absorption chiller system decreased by 40% in the same generator temperature range. On the other hand, COP of all double-effect absorption chiller systems increased about 8 % when the generator temperature was changed from 116 ºC to 155 ºC while the exergetic performance of all double absorption chiller systems decreased by around 14% for the same generator temperature range. The COP and exergetic efficiency values of the double-effect parallel system were found to be higher than other absorption systems at all generator temperature values. Overall, this study recommends that the double-effect parallel absorption chiller systems can be preferred for the factories having waste heat source wood chips. The average payback period of the system was also found to be 1.4 years. Furthermore, this study shows that double-effect parallel absorption chiller systems can be proposed for the facilities having wood chips waste sources instead of double-effect reverse parallel absorption chiller systems since they are easy to operate and have lower maintenance costs.

Energy, Exergy and Economic Analysis of Absorption Chiller Systems: A Case Study for a Wood Pencil Factory

This study examines the use of absorption chiller systems in a designated industrial facility having waste heat by conducting energy, exergy and economic analyses. The absorption chiller systems namely single-effect, double-effect series, double-effect parallel and double-effect reverse parallel were analysed to determine the best alternative for the wood pencil factory. The results indicated that the COP of the single-effect absorption chiller systems is changed from 0.758 to 0.763 when the temperature of the generator was increased from 89 ºC to 125 ºC. However, the exergetic performance of the single-effect absorption chiller system decreased by 40% in the same generator temperature range. On the other hand, COP of all double-effect absorption chiller systems increased about 8 % when the generator temperature was changed from 116 ºC to 155 ºC while the exergetic performance of all double absorption chiller systems decreased by around 14% for the same generator temperature range. The COP and exergetic efficiency values of the double-effect parallel system were found to be higher than other absorption systems at all generator temperature values. Overall, this study recommends that the double-effect parallel absorption chiller systems can be preferred for the factories having waste heat source wood chips. The average payback period of the system was also found to be 1.4 years. Furthermore, this study shows that double-effect parallel absorption chiller systems can be proposed for the facilities having wood chips waste sources instead of double-effect reverse parallel absorption chiller systems since they are easy to operate and have lower maintenance costs.

Energy, Exergy and Economic Analysis of Absorption Chiller Systems: A Case Study for a Wood Pencil Factory

This study examines the use of absorption chiller systems in a designated industrial facility having waste heat by conducting energy, exergy and economic analyses. The absorption chiller systems namely single-effect, double-effect series, double-effect parallel and double-effect reverse parallel were analysed to determine the best alternative for the wood pencil factory. The results indicated that the COP of the single-effect absorption chiller systems is changed from 0.758 to 0.763 when the temperature of the generator was increased from 89 ºC to 125 ºC. However, the exergetic performance of the single-effect absorption chiller system decreased by 40% in the same generator temperature range. On the other hand, COP of all double-effect absorption chiller systems increased about 8 % when the generator temperature was changed from 116 ºC to 155 ºC while the exergetic performance of all double absorption chiller systems decreased by around 14% for the same generator temperature range. The COP and exergetic efficiency values of the double-effect parallel system were found to be higher than other absorption systems at all generator temperature values. Overall, this study recommends that the double-effect parallel absorption chiller systems can be preferred for the factories having waste heat source wood chips. The average payback period of the system was also found to be 1.4 years. Furthermore, this study shows that double-effect parallel absorption chiller systems can be proposed for the facilities having wood chips waste sources instead of double-effect reverse parallel absorption chiller systems since they are easy to operate and have lower maintenance costs.

A Comprehensive Thermoeconomic Evaluation and Multi-Criteria Optimization of a Combined MCFC/TEG System

In this study, an integrated molten carbonate fuel cell (MCFC), thermoelectric generator (TEG), and regenerator energy system has been introduced and evaluated. MCFC generates power and heating load. The exit fuel gases of the MCFC is separated into three sections: the first section is transferred to the TEG to generate more electricity, the next chunk is conducted to a regenerator to boost the productivity of the suggested plant and compensate for the regenerative destructions, and the last section enters the surrounding. Computational simulation and thermodynamic evaluation of the hybrid plant are carried out utilizing MATLAB and HYSYS software, respectively. Furthermore, a thermoeconomic analysis is performed to estimate the total cost of the product and the system cost rate. The offered system is also optimized using multi-criteria genetic algorithm optimization to enhance the exergetic efficiency while reducing the total cost of the product. The power generated by MCFC and TEG is 1247.3 W and 8.37 W, respectively. The result explicates that the provided electricity and provided efficiency of the suggested plant is 1255.67 W and 38%, respectively. Exergy inquiry outcomes betokened that, exergy destruction of the MCFC and TEG is 13,945.9 kW and 262.75 kW, respectively. Furthermore, their exergy efficiency is 68.22% and 97.31%, respectively. The impacts of other parameters like working temperature and pressure, thermal conductance, the configuration of the advantage of the materials, etc., on the thermal and exergetic performance of the suggested system are also evaluated. The optimization outcomes reveal that in the final optimum solution point, the exergetic efficiency and total cost of the product s determined at 70% and 30 USD/GJ.

Design and Analysis of a Solar Energy Driven Tri-generation Plant for power, Heating and Refrigeration

A tri-generation plant producing power, heat and refrigeration has been designed and analyzed. Using solar energy as input. The power side of the plant employs supercritical carbon dioxide (sCO2) recompression cycle. The refrigeration side includes an aqueous lithium bromide absorption system. Thermal energy has been extracted from many places in the plant for heating purposes. A detailed thermodynamics model has been developed to determine performance of the plant for many different conditions. Thermal efficiency, energy effectiveness and exergetic efficiency of the system has been calculated for different operating conditions. It turns out that the pressure ratio of the recombination cycle and effectiveness of the energy exchanger for transferring energy from the power side to the refrigeration side play important roles.

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

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.

METODOLOGIA TERMODINÂMICA PARA CÁLCULO DE EFICIÊNCIA EXERGÉTICA EM CIDADES CONTEMPORÂNEAS / THERMODYNAMIC APPROACH FOR EVALUATION OF EXERGETIC EFFICIENCY OF CONTEMPORARY CITIES

O crescente interesse por sustentabilidade energética induz a procura por ferramentas teóricas concisas para o cálculo e comparação de parâmetros de interesse. O cálculo de eficiência termodinâmica para avaliação das cidades e sua analogia com máquinas térmicas é indicado para o estudo de cidades sustentáveis. No entanto, o cálculo de eficiência termodinâmica de máquinas térmicas aplicados a cidades tem uma dificuldade principal: a definição formal de fluxo de produção das cidades em termos de propriedades termodinâmicas, e que seja aplicável para qualquer cidade independente de sua formação histórica, localização, clima, cultura, economia, etc. Este artigo visa estabelecer o arcabouço teórico para cálculo da produção das cidades através de propriedades termodinâmicas, a dinâmica de consumo e transformação de massa e energia dentro das cidades, geração de irreversibilidades e a aplicação da propriedade exergia como parâmetro universal de análise termodinâmica das cidades. Para exemplificar, apresentam-se valores obtidos para eficiência exergética de cinco cidades da América Latina, apresentados em seminário acadêmico sobre eficiência das cidades dentro do escopo de avaliação de disciplinas optativas do curso de engenharia de energia da UNILA.