The Experts below are selected from a list of 81 Experts worldwide ranked by ideXlab platform

Carlos Eduardo Keutenedjian Mady - One of the best experts on this subject based on the ideXlab platform.

  • phenomenological and thermodynamic model of gas exchanges in the placenta during pregnancy a case study of intoxication of carbon monoxide
    International Journal of Environmental Research and Public Health, 2019
    Co-Authors: Juliana Rangel Cenzi, Cyro Albuquerque, Carlos Eduardo Keutenedjian Mady
    Abstract:

    The present work simulates the transport of oxygen, carbon dioxide, and carbon monoxide between a fetus’s circulatory system and the mother’s. The organ responsible for this exchange is the placenta. Carbon monoxide is a common air pollutant, and it impacts the physiological conditions even in low concentration. The impacts of carbon monoxide are especially dangerous for pregnant women, fetuses, and newborn babies. A model of carbon monoxide transport, from the literature, is modified to simulate a pregnant woman (original model was a male), therefore changing some parameters to express the adjusted respiratory system. It was considered the gas exchange in the placenta, to evaluate the concentration of these different gases in the fetus arterial and venous blood. Three methods of the Exergy analysis are implemented for both mother and fetus respiratory systems, aiming at the comparison with the respiratory system of a male adult. The destroyed Exergy of the literature did not have the same trend as the models proposed in this article, taking into consideration the hemoglobin reactions. In contrast, the entropy generation associated only with the diffusion transport phenomena was one order of magnitude lower than the other methods. The placenta destroyed Exergy Rate is significantly higher compared to the irreversibilities of the mother’s respiratory system. One possible explanation is the fact that the placenta has other physiological functions than gas transportation.

F W Adam - One of the best experts on this subject based on the ideXlab platform.

  • experimental investigation of the drying characteristics of a mixed mode natural convection solar crop dryer with back up heater
    Journal of Energy Technologies and Policy, 2017
    Co-Authors: C K K Sekyere, F K Forson, F W Adam
    Abstract:

    An experimental investigation into the thermal buoyancy characteristics of a mixed-mode natural convection solar crop dryer with back up heater is described. Twenty seven carefully planned tests were conducted under no load conditions for plenum inlet gap to vent outlet gap ratios of 1:1, 1:1.3 and 1:1.5, in order to determine the optimum thermal drive characteristics of the dryer. Air velocities, temperatures, ambient relative humidity, collector efficiency, Exergy Rate of change, thermal mass entropy change and air mass flow Rate are presented. The effects of the various plenum inlet and vent outlet gap configurations described above on dryer thermal buoyancy are deduced and discussed. Results show that for all heating modes, an air inlet gap to vent gap ratio of 1.5:1 optimises the thermal performance of the dryer. Keywords : Solar dryer, back up heater, Exergy, plenum, thermal mass

Forson F.k. - One of the best experts on this subject based on the ideXlab platform.

  • Experimental Investigation of the Thermal Buoyancy Characteristics of a Mixed Mode Natural Convection Solar Crop Dryer with Back Up Heater
    Journal of Energy Technologies and Policy, 2017
    Co-Authors: Sekyere C.k.k., Adam F.w., Davis F., Forson F.k.
    Abstract:

    An experimental investigation into the thermal buoyancy characteristics of a mixed-mode natural convection solar crop dryer with back up heater is described. Twenty seven carefully planned tests were conducted under no load conditions for plenum inlet gap to vent outlet gap ratios of 1:1, 1:1.3 and 1:1.5, in order to determine the optimum thermal drive characteristics of the dryer. Air velocities, temperatures, ambient relative humidity, collector efficiency, Exergy Rate of change, thermal mass entropy change and air mass flow Rate are presented. The effects of the various plenum inlet and vent outlet gap configurations described above on dryer thermal buoyancy are deduced and discussed. Results show that for all heating modes, an air inlet gap to vent gap ratio of 1.5:1 optimises the thermal performance of the dryer. Keywords: Solar dryer, back up heater, Exergy, plenum, thermal mas

Muthusamy V Swami - One of the best experts on this subject based on the ideXlab platform.

  • Exergy economic and environmental analysis of forced circulation flat plate solar collector using heat transfer enhancer in riser tube
    Journal of Cleaner Production, 2018
    Co-Authors: K. Balaji, S. Iniyan, Muthusamy V Swami
    Abstract:

    Abstract This paper experimentally investigates the Exergy of a riser tube with heat transfer enhancer in the flat plate collector. Two different internal heat transfer enhancers are used herein, namely, rod heat transfer enhancer and tube heat transfer enhancer. The environmental and sustainable assessment of the flat plate collector with and without heat transfer enhancer have been taken into consideration in the study. This is the first study performed on the Exergy and economic analysis of a flat plate solar collector using this heat transfer enhancer, and the new findings on the Exergy analysis using heat transfer enhancer of the flat plate collector have been reported. The improved Exergy efficiency, useful Exergy Rate and Exergy destruction for the flat plate collector are analyzed, and it is found that the rod heat transfer enhancer provides comparatively higher Exergy efficiency than the tube heat transfer enhancer and plain tube flat plate collector. The maximum Exergy efficiency is 11.3%, 10.9% and 8.3% for the rod, tube heat transfer enhancers, and plain tube respectively. The heat transfer enhanced collectors significantly reduce the total Exergy destruction compared to plain tube collector. The increase in useful Exergy Rate is 1.29 and 1.25 times higher for the rod and tube heat transfer enhancers respectively, compared to the plain tube collector. The conclusion is that the rod heat transfer enhancer collector has the lowest energy payback time and a simple payback period.

Liza Cipolato - One of the best experts on this subject based on the ideXlab platform.

  • Exergetic analysis of cascade cycle for natural gas liquefaction
    2017
    Co-Authors: Liza Cipolato
    Abstract:

    Resumo: O comércio de gás natural liquefeito apresenta um crescente interesse por parte tanto de países exportadores como dependentes desta fonte energética. Apesar de o transporte por gasoduto ser muito menos suscetível a perdas, ele se torna inviável a longas distâncias ou a demandas variáveis. A liquefação do gás natural também proporciona o armazenamento desta fonte energética numa forma estável e de alto potencial energético,evidenciando o caráter estratégico do processo. Desde a década de 60 a tecnologia para liquefação do gás natural é utilizada, porém, apenas há alguns anos os países iniciaram ocomércio desta fonte energética em larga escala e isto acarretará um aumento mundial tanto no número de terminais exportadores (plantas de liquefação) quanto importadores (terminais de regaseificação). O processo de liquefação do gás natural ocorre através de uma sequência de ciclos termodinâmicos de refrigeração, e estes, por sua vez, precisam trabalhar de forma otimizada para reduzir perdas. A análise exergética é uma ferramenta muito útil para avaliar estas perdas e pode ser essencial na instalação de uma nova planta ou melhoria de uma já existente. O presente trabalho realizou uma análise exergética de umciclo de refrigeração utilizado para a liquefação de gás natural, o qual é do tipo multiestágio em cascata, padrão utilizado atualmente, sendo o mais conhecido e difundido entre as indústrias da área. Primeiramente, o processo foi simulado em software comercial Hysys (versão 3.2 da Aspen Technology). O resultado obtido da simulação foi validado através de comparação com dados da literatura, mostrando-se adequado. Em seguida, a simulação foi testada em diferentes condições operacionais, seguindo um planejamento fatorial completo, o qual teve como objetivo verificar a influência da variação das pressões de seis pontos específicos do ciclo sobre a variável resposta, que é a taxa de exergia total destruída no processo, visando sua minimização. Os resultados obtidos levaram a uma nova condição de operação para o ciclo de refrigeração com redução de aproximadamente 48% da taxa de exergia destruída com relação aos dados do caso obtido da literatura. Tal resultadoevidencia o potencial da metodologia termodinâmica utilizada, demonstrando sua aplicação em estudos de melhoria do desempenho de ciclos de refrigeração para a indústria de liquefação de gás naturalAbstract: The liquefied natural gas trade shows a growing interest either from countries which are exporters or countries which depend on this kind of energetic source. Although gas pipelines are less susceptible of transportation losses, they become impracticable when distances are too long or when demands are highly variable. The liquefaction of natural gas also enables its storage in a stable way, in which energetic potential is high, expressing the stRategic purpose of the process. Since the 1960 decade natural gas liquefying technology is been used, but only a few years ago countries have started the trade of this kind of energetic source on a large scale. Consequently, the number of exporter terminals (liquefaction industries) and importer terminals (regasification plants) will increase worldwide. The natural gas liquefaction process is based on a sequence of refrigeration thermodynamics cycles, which need to work in an optimized way in order to reduce losses. The Exergy analysis is a very useful tool to evaluate these losses and can be crucial in a new plant installation or in a current one improvement. This dissertation performed an Exergy analysis of a multistage cascade refrigeration cycle applied in natural gas liquefaction. The multistage cascade cycle is currently the standard type, being the most known and diffused among industries. Firstly, the process was simulated in commercial software Hysys (version 3.2 of Aspen Technology). The result obtained from the simulation was validatedby comparison with the literature data and showed a very adequate similarity. After that, the simulation was checked in different operational conditions, according to the complete factorial design of experiments. The design of experiments? objective was to verify the pressure influence of six specific points of the cycle over the response variable, which is the Rate of total Exergy destroyed in the cycle, in order to reach its minimal value. The results showed a new operational condition to the refrigeration cycle, in which the destroyed Exergy Rate was reduced by approximately 48% in comparison with literature data. This result provides evidence of the high potential of the thermodynamic tool used, showing its application in studies of performance improvements for refrigeration cycles in industries of natural gas liquefactio

  • Exergetic analysis of cascade cycle for natural gas liquefaction
    Universidade Estadual de Campinas . Faculdade de Engenharia Química, 2008
    Co-Authors: Liza Cipolato
    Abstract:

    O comércio de gás natural liquefeito apresenta um crescente interesse por parte tanto de países exportadores como dependentes desta fonte energética. Apesar de o transporte por gasoduto ser muito menos suscetível a perdas, ele se torna inviável a longas distâncias ou a demandas variáveis. A liquefação do gás natural também proporciona o armazenamento desta fonte energética numa forma estável e de alto potencial energético,evidenciando o caráter estratégico do processo. Desde a década de 60 a tecnologia para liquefação do gás natural é utilizada, porém, apenas há alguns anos os países iniciaram o comércio desta fonte energética em larga escala e isto acarretará um aumento mundial tanto no número de terminais exportadores (plantas de liquefação) quanto importadores (terminais de regaseificação). O processo de liquefação do gás natural ocorre através de uma sequência de ciclos termodinâmicos de refrigeração, e estes, por sua vez, precisam trabalhar de forma otimizada para reduzir perdas. A análise exergética é uma ferramenta muito útil para avaliar estas perdas e pode ser essencial na instalação de uma nova planta ou melhoria de uma já existente. O presente trabalho realizou uma análise exergética de um ciclo de refrigeração utilizado para a liquefação de gás natural, o qual é do tipo multiestágio em cascata, padrão utilizado atualmente, sendo o mais conhecido e difundido entre as indústrias da área. Primeiramente, o processo foi simulado em software comercial Hysys (versão 3.2 da Aspen Technology). O resultado obtido da simulação foi validado através de comparação com dados da literatura, mostrando-se adequado. Em seguida, a simulação foi testada em diferentes condições operacionais, seguindo um planejamento fatorial completo, o qual teve como objetivo verificar a influência da variação das pressões de seis pontos específicos do ciclo sobre a variável resposta, que é a taxa de exergia total destruída no processo, visando sua minimização. Os resultados obtidos levaram a uma nova condição de operação para o ciclo de refrigeração com redução de aproximadamente 48% da taxa de exergia destruída com relação aos dados do caso obtido da literatura. Tal resultado evidencia o potencial da metodologia termodinâmica utilizada, demonstrando sua aplicação em estudos de melhoria do desempenho de ciclos de refrigeração para a indústria de liquefação de gás naturalThe liquefied natural gas trade shows a growing interest either from countries which are exporters or countries which depend on this kind of energetic source. Although gas pipelines are less susceptible of transportation losses, they become impracticable when distances are too long or when demands are highly variable. The liquefaction of natural gas also enables its storage in a stable way, in which energetic potential is high, expressing the stRategic purpose of the process. Since the 1960 decade natural gas liquefying technology is been used, but only a few years ago countries have started the trade of this kind of energetic source on a large scale. Consequently, the number of exporter terminals (liquefaction industries) and importer terminals (regasification plants) will increase worldwide. The natural gas liquefaction process is based on a sequence of refrigeration thermodynamics cycles, which need to work in an optimized way in order to reduce losses. The Exergy analysis is a very useful tool to evaluate these losses and can be crucial in a new plant installation or in a current one improvement. This dissertation performed an Exergy analysis of a multistage cascade refrigeration cycle applied in natural gas liquefaction. The multistage cascade cycle is currently the standard type, being the most known and diffused among industries. Firstly, the process was simulated in commercial software Hysys (version 3.2 of Aspen Technology). The result obtained from the simulation was validated by comparison with the literature data and showed a very adequate similarity. After that, the simulation was checked in different operational conditions, according to the complete factorial design of experiments. The design of experiments? objective was to verify the pressure influence of six specific points of the cycle over the response variable, which is the Rate of total Exergy destroyed in the cycle, in order to reach its minimal value. The results showed a new operational condition to the refrigeration cycle, in which the destroyed Exergy Rate was reduced by approximately 48% in comparison with literature data. This result provides evidence of the high potential of the thermodynamic tool used, showing its application in studies of performance improvements for refrigeration cycles in industries of natural gas liquefactio