The Experts below are selected from a list of 318 Experts worldwide ranked by ideXlab platform
Fan Ya-yun - One of the best experts on this subject based on the ideXlab platform.
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Theoretic analysis of direct expansion solar-assisted heat pump system
Renewable Energy, 2005Co-Authors: Fan Ya-yunAbstract:In this paper,general principle of direct expansion solar-assisted heat pump is presented.According to thermodynamic law,theoretic circulation of direct expansion solar-assisted heat pump is analysed,energy Balance equations and Exergy Balance equations of the main instruments in a direct expansion solar-assisted heat pump system are gived and COP and Exergy efficiency of the system is analysed.
Masanori Shukuya - One of the best experts on this subject based on the ideXlab platform.
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Sensitivity Numerical Analysis of Human Body Exergy Balance under an Unsteady-State Thermal Environment —Behavioral Adaptation Induced by Undesirable Cold Storage by Building Envelope in Winter
Health, 2016Co-Authors: Koichi Isawa, Masanori ShukuyaAbstract:We analyzed the relationships between the human body Exergy Balance and behavioral adaptations induced by undesirable cold storage by a building envelope under an unsteady-state thermal environment in winter. The complex interaction of the warm Exergy production by shivering, lifting of the shell ratio, and reduction of the blood flow rate was considered to constitute the physiological adaptation necessary for maintaining the constant core temperature, which was an important aspect in living organisms. In the case of intermittent use room, it was suggested that better thermal comfort and desirable behavioral adaptations, which decreased the consumption of fossil fuels, could be achieved if interior wooden cladding was used in constructions with building envelopes that had a comparatively large heat capacity, or in cases of wooden constructions in which the building envelope heat capacity was comparatively small.
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Exergetic issues of thermoregulation physiology in different climates
International Journal of Exergy, 2015Co-Authors: Mateja Dovjak, Masanori ShukuyaAbstract:The purpose of the paper is to analyse the physiology of thermoregulation in various climate types using human body Exergy Balance model where mutual influence of environmental parameters and personal factors are considered. Two virtual persons with different metabolic rates and effective clothing insulations were exposed to selected climate conditions. Human body Exergy Balance (hBExB) was calculated with software developed by Hideo Asada Rev 2010. Results showed that climate conditions in combination with metabolic rate and effective clothing insulation had large influence on every part of hBExB. Thermally comfortable conditions with PMV index closer to 0 did not always result in the lowest possible hbExC rate. The value of hbExC rate strongly depends on environmental parameters as well as on metabolic rate and effective clothing insulation. Understanding the mutual influence of environmental parameters and personal factors on hBExB is a key factor for identifying recommendations for healthy, comfortable and stimulative conditions.
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development of human body Exergy Balance model for a better understanding of thermal comfort in the built environment
International Journal of Exergy, 2012Co-Authors: Masanori Shukuya, Toshiya Iwamatsu, Hideo AsadaAbstract:This paper briefly describes the human–body Exergy Balance equation developed so far applying a variety of formulae derived from the fundamentals of thermodynamics, namely the concepts of wet/dry Exergy associated with moist air and liquid water, warm/cool Exergy transferred by radiation and convection. A couple of numerical examples of the whole human–body Exergy Balance are given and discussed in relations to mean radiant temperature, room air temperature, air velocity, and outdoor environmental temperature. We have found so far that it is very important to control the amount of thermal radiant Exergy in room space both in winter and in summer.
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Development of human–body Exergy Balance model for a better understanding of thermal comfort in the built environment
International Journal of Exergy, 2012Co-Authors: Masanori Shukuya, Toshiya Iwamatsu, Hideo AsadaAbstract:This paper briefly describes the human–body Exergy Balance equation developed so far applying a variety of formulae derived from the fundamentals of thermodynamics, namely the concepts of wet/dry Exergy associated with moist air and liquid water, warm/cool Exergy transferred by radiation and convection. A couple of numerical examples of the whole human–body Exergy Balance are given and discussed in relations to mean radiant temperature, room air temperature, air velocity, and outdoor environmental temperature. We have found so far that it is very important to control the amount of thermal radiant Exergy in room space both in winter and in summer.
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Calculation of Human-body Exergy Balance for Investigating Thermal Comfort under Transient Conditions
2012Co-Authors: Masanori Shukuya, Kayo Tokunaga, Moe Onoma, Yasuyuki ItohAbstract:Application of the concept of Exergy to human-body thermo-physical phenomena has revealed so far the following: mean radiant temperature, which is a little higher than air temperature, provides the human body with the lowest possible Exergy consumption rate for winter conditions; and a combination of mean radiant temperature, which is a little lower than air temperature, and moderate air velocity to be given by natural ventilation provides the human body with the lowest possible Exergy consumption rate for summer conditions. Supposing that it will become important to have an exergetic understanding on the adaptive behaviour of occupants in the built environment, we have tried a couple of unsteady-state calculation of human-body Exergy Balance for summer and winter conditions. As the results, we confirmed that it is essential to take a variety of passive technology prior to that of active technology for realizing low-Exergy space heating and cooling systems.
Koichi Isawa - One of the best experts on this subject based on the ideXlab platform.
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Sensitivity Numerical Analysis of Human Body Exergy Balance under an Unsteady-State Thermal Environment —Behavioral Adaptation Induced by Undesirable Cold Storage by Building Envelope in Winter
Health, 2016Co-Authors: Koichi Isawa, Masanori ShukuyaAbstract:We analyzed the relationships between the human body Exergy Balance and behavioral adaptations induced by undesirable cold storage by a building envelope under an unsteady-state thermal environment in winter. The complex interaction of the warm Exergy production by shivering, lifting of the shell ratio, and reduction of the blood flow rate was considered to constitute the physiological adaptation necessary for maintaining the constant core temperature, which was an important aspect in living organisms. In the case of intermittent use room, it was suggested that better thermal comfort and desirable behavioral adaptations, which decreased the consumption of fossil fuels, could be achieved if interior wooden cladding was used in constructions with building envelopes that had a comparatively large heat capacity, or in cases of wooden constructions in which the building envelope heat capacity was comparatively small.
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Human Body Exergy Balance: Numerical Analysis of an Indoor Thermal Environment of a Passive Wooden Room in Summer
Buildings, 2015Co-Authors: Koichi IsawaAbstract:To obtain a basic understanding of the resultant changes in the human body Exergy Balance (input, consumption, storage, and output) accompanying outdoor air temperature fluctuations, a “human body system and a built environmental system” coupled with numerical analysis was conducted. The built environmental system assumed a wooden room equipped with passive cooling strategies, such as thermal insulation and solar shading devices. It was found that in the daytime, the cool radiation Exergy emitted by surrounding surfaces, such as walls increased the rate of human body Exergy consumption, whereas the warm radiant Exergy emitted by the surrounding surfaces at night decreased the rate of human body Exergy consumption. The results suggested that the rates and proportions of the different components in the Exergy Balance equation (Exergy input, consumption, storage, and output) vary according to the outdoor temperature and humidity conditions.
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Sensitivity Analysis on the Relationship Between Building Envelope Material and Human Body Exergy Balance
Energy Procedia, 2015Co-Authors: Koichi IsawaAbstract:Abstract This study is reports the calculations of human body Exergy Balance and its applicability to measurement of human comfort indoors. Using equations for human body Exergy Balance, I calculated the integrated Exergy consumption for enclosures made of wood, metal, and concrete of varying thicknesses. For maximum thermal comfort, the integrated Exergy consumption should be minimized, and I found that for typical winter and intermediate season conditions in Shizuoka, Japan, a wooden enclosure offers more thermal comfort than concrete and metal structures for cases of no insulation and no heating source. This study reaches conclusions similar to those of another experiment performed on the survivability of mice in various enclosures in different thermal environments.
S.k. Som - One of the best experts on this subject based on the ideXlab platform.
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Thermodynamic irreversibilities and Exergy Balance in combustion processes
Progress in Energy and Combustion Science, 2008Co-Authors: S.k. Som, Amitava DattaAbstract:The growing concern for energy, economy and environment calls for an efficient utilization of natural energy resources in developing useful work. An important thermodynamic aspect in gauging the overall energy economy of any physical process is the combined energy and Exergy analysis from the identification of process irreversibilities. The present paper makes a comprehensive review pertaining to fundamental studies on thermodynamic irreversibility and Exergy analysis in the processes of combustion of gaseous, liquid and solid fuels. The need for such investigations in the context of combustion processes in practice is first stressed upon and then the various approaches of Exergy analysis and the results arrived at by different research workers in the field have been discussed. It has been recognized that, in almost all situations, the major source of irreversibilities is the internal thermal energy exchange associated with high-temperature gradients caused by heat release in combustion reactions. The primary way of keeping the Exergy destruction in a combustion process within a reasonable limit is to reduce the irreversibility in heat conduction through proper control of physical processes and chemical reactions resulting in a high value of flame temperature but lower values of temperature gradients within the system. The optimum operating condition in this context can be determined from the parametric studies on combustion irreversibilities with operating parameters in different types of flames.
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Energy and Exergy Balance in the Process of Pulverized Coal Combustion in a Tubular Combustor
Journal of Heat Transfer, 2005Co-Authors: S.k. Som, S. S. Mondal, Sukanta K. DashAbstract:A theoretical model of Exergy Balance, based on availability transfer and flow availability, in the process of pulverized coal combustion in a tubular air-coal combustor has been developed to evaluate the total thermodynamic irreversibility and second law efficiency of the process at various operating conditions. The velocity, temperature, and concentration fields required for the evaluation of flow availability have been computed numerically from a two-phase separated flow model on a Eulerian-Lagrangian frame in the process of combustion of pulverized coal particles in air. The total thermodynamic irreversibility in the process has been determined from the difference in the flow availability at the inlet and outlet of the combustor. A comparative picture of the variations of combustion efficiency and second law efficiency at different operating conditions, such as inlet pressure and temperature of air, total air flow rate and inlet air swirl, initial mean particle diameter, and length of the combustor, has been provided to shed light on the trade-off between the effectiveness of combustion and the lost work in the process of pulverized coal combustion in a tubular combustor.
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Energy and Exergy Balance in the Process of Spray Combustion in a Gas Turbine Combustor
Journal of Heat Transfer, 2002Co-Authors: S.k. Som, N. Y. SharmaAbstract:A theoretical model of Exergy Balance based on availability transfer and flow availability in the process of spray combustion in a gas turbine combustor has been developed to evaluate the total thermodynamic irreversibility and second law efficiency of the process at various operating conditions, for fuels with different volatilities. The velocity, temperature and concentration fields in the combustor, required for the evaluation of the flow availabilities and process irreversibilities, have been computed numerically from a two phase separated flow model of spray combustion. The total thermodynamic irreversibility in the process of spray combustion has been determined from the difference in the flow availability at inlet and outlet of the combustor. The irreversibility caused by the gas phase processes in the combustor has been obtained from the entropy transport equation, while that due to the inter-phase transport processes has been obtained as a difference of gas phase irreversibilities from the total irreversibility. A comparative picture of the variations of combustion efficiency and second law efficiency at different operating conditions for fuels with different volatilities has been made to throw light on the trade off between the effectiveness of combustion and the lost work in the process of spray combustion in a gas turbine combustor.
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Energy and Exergy Balance in a gas turbine combustor
Proceedings of the Institution of Mechanical Engineers Part A: Journal of Power and Energy, 1999Co-Authors: Amitava Datta, S.k. SomAbstract:AbstractAn energy and Exergy Balance in the process of spray combustion in a model tubular gas turbine combustor has been made to determine the combustion efficiency and second law efficiency of th...
Amitava Datta - One of the best experts on this subject based on the ideXlab platform.
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Thermodynamic irreversibilities and Exergy Balance in combustion processes
Progress in Energy and Combustion Science, 2008Co-Authors: S.k. Som, Amitava DattaAbstract:The growing concern for energy, economy and environment calls for an efficient utilization of natural energy resources in developing useful work. An important thermodynamic aspect in gauging the overall energy economy of any physical process is the combined energy and Exergy analysis from the identification of process irreversibilities. The present paper makes a comprehensive review pertaining to fundamental studies on thermodynamic irreversibility and Exergy analysis in the processes of combustion of gaseous, liquid and solid fuels. The need for such investigations in the context of combustion processes in practice is first stressed upon and then the various approaches of Exergy analysis and the results arrived at by different research workers in the field have been discussed. It has been recognized that, in almost all situations, the major source of irreversibilities is the internal thermal energy exchange associated with high-temperature gradients caused by heat release in combustion reactions. The primary way of keeping the Exergy destruction in a combustion process within a reasonable limit is to reduce the irreversibility in heat conduction through proper control of physical processes and chemical reactions resulting in a high value of flame temperature but lower values of temperature gradients within the system. The optimum operating condition in this context can be determined from the parametric studies on combustion irreversibilities with operating parameters in different types of flames.
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Energy and Exergy Balance in a gas turbine combustor
Proceedings of the Institution of Mechanical Engineers Part A: Journal of Power and Energy, 1999Co-Authors: Amitava Datta, S.k. SomAbstract:AbstractAn energy and Exergy Balance in the process of spray combustion in a model tubular gas turbine combustor has been made to determine the combustion efficiency and second law efficiency of th...