© ECOS 2021 - 34th International Conference on Efficency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems.This work intends to assess the characteristics, penalties, gains, and challenges through the Electrification and Hybridization process for long-range aircraft. A system, engines and mission level analysis was created focusing on a Thermodynamics and financial approach. A conventional reference aircraft was compared with enhanced more electric and hybrid-electric versions of itself. These new models may carry batteries, which supply the aircraft systems and/or engines, or not. State-of-the-art propulsion and systems’ architecture were also implemented within the cutting-edge airplanes. A full factorial analysis was conducted to vary the batteries’ energy density and the hybridization ratio for the hybrid configurations. A typical mission profile was developed to match the boundary conditions in all cases. Hybrid powertrains confirmed superior behavior than any other cases. The least efficient hybrid configuration, with intermediate battery choices, reduced 10.7% the fuel consumption upon the conventional aircraft and 1.0% facing the battery powered more electric option. Moreover, both baseline models were also surpassed by the worst midway-battery hybrid airplane by 3.6% and 1.0% in overall mission exergy efficiency. Notwithstanding the markets’ actual low battery density, long-range hybrid-electric aircraft will take substantial time to become viable. Nevertheless, only after a significant period, the use of hybrid-electric aircraft will be economically feasible. In the end, preliminary well-to-wake CO2 emissions analysis was developed in all cases for different electricity mix scenarios to observe the environmental impact and viability of the conventional and state-of-the-art configurations.

© ECOS 2020.All right reserved.Focusing on the great challenges of space exploration for the coming decades, there is a need for more efficient and compact energy conversion systems for space applications. To this end, a thermodynamic model was applied to analyze the energy and exergy efficiency of space nuclear power plant that operates with freepiston Stirling cycle for deep space exploration purposes. The model considered conduction losses (thermal bridge), heat pipe efficiency, finite regeneration time, and radiation losses. Thermodynamic irreversibilities of the reactor, regenerator, and radiator were computed in order to find which component is accountable for the highest exergy destruction. Results have shown that most of the exergy is destroyed in the regenerator and the radiator. With the increasing radiator area, the irreversibility of the radiator tends to decrease, but the mass per power output ratio also decreases. The optimum power output per radiator area and mass per radiator area pointed for 2.697m2of the radiator area for this energy conversion system. Furthermore, it was evidenced that the regenerator effectiveness considerably influences the overall cycle efficiency, as well as reference temperature (environment) and cold source temperature. These results can provide relevant guidelines for future design of a space power plant where the Stirling cycle is the chosen dynamic energy conversion system.

© 2020 Inderscience Enterprises Ltd.In the present work, the rate of living theory and exergy analysis are gathered to assess the effects of cancer on life expectancy. An exergy model of a cancer cell metabolism is proposed taking into account the changes in the metabolic paths. Results indicate a threefold increase in the rate of exergy metabolism of a cancer cell. Moreover, per mole of glucose, a cancer cell obtains 8.9 moles of ATP against 32 synthesised by a healthy one. However, because of the increase in the rate of glucose uptake, the metabolic routes of the tumour are less efficient but are faster. The analysis of a generic tumour progression indicates that, in the absence of treatment, survival time would be around three years. Furthermore, in case of complete removal of the tumour, every six months living with the disease would lead to a reduction of almost four years in life expectancy.

© 2018 Elsevier LtdThis paper describes how the scientific contributions of Prof. Szargut and his co-workers have inspired the academic activities of the Exergy Team of the Laboratory of Environmental and Thermal Engineering (LETE) of the Polytechnic School of the University of Sao Paulo. The work of Prof. Szargut was at first used for preparing a course on Exergy Analysis, which has been taught since 1992 to MSc and Ph.D. students of the graduate program in Mechanical Engineering of the Polytechnic School of the University of Sao Paulo. Since then, the methods and concepts established by Prof. Szargut have played an important role in the development of the various research lines at LETE for the past fifteen years. Complex thermodynamic systems, such as petroleum production and refining plants, biofuel production routes, combined production of ethanol and electricity technologies, aircraft systems, environmental impact mitigation processes, CO2 capture units, ammonia production facilities, and the human body and its systems were analyzed using the concepts and tools suggested by Prof Szargut. The present article illustrates how the application of exergy analysis, thermoeconomic and environmental performance indicators, cumulative exergy consumption, definition of reference environment and chemical exergy can serve different purposes when evaluating thermodynamic systems.

© 2017 IMEKOThe present work evaluates the impact of carbon monoxide inhalation in the human lungs exergy behaviour for different levels of intoxications and altitude. It is significant because this substance is one of the most common air pollutants in cities and an increasing in the destroyed exergy can be associated with a reduction in lifespan. Moreover, an evaluation of the severity as a function of the city height may intensify the hazard associated with carbon monoxide. In order to evaluate these consequences, a carbon monoxide transportation model obtained in literature was used to calculate the concentrations of oxygen, carbon monoxide and carbon dioxide in the different respiratory system tissues. With the purpose to better evaluate the different levels of carbon monoxide intoxication and hemoglobin concentration (which is a function of acclimatization time) it was proposed an exergy efficiency for the lungs. From this model, it was possible to conclude that a higher level of intoxication is associated to lower exergy efficiency values. Higher hemoglobin levels when associated to carbon monoxide intoxication also results in lower efficiencies.

© 2017 IMEKOIn the past few years, different scientific papers have proposed the use of an exergy perspective to analyze some physiological systems of the human body under different physical and environmental conditions. Such perspective, focused on the exergy transformations and the efficiency of the biological processes, which may aid the medical field in its assessment of a patient’s physical health. Following this concept, this paper proposes a model of the human cardiovascular system in order to calculate the exergy transfers and its destruction from the intrasystemic and intersystemic interactions, taking into account all significant energy conversion processes that involve the heart and the blood vessels as blood circulates in both the systemic and the pulmonary circulations. With this model, a 7.86 W exergy destruction was obtained for a person under basal conditions. As a follow-up, a statistical model was developed to describe the evolution of the transvalvular pressure gradient in the aortic valve as a valve stenosis becomes more severe. This model was created using physiological data from 40 patients available in the literature, as well as 32 operating points from different Bileaflet aortic valve prosthesis. A final logarithmic regression resulted in a 14.6 kPa (109.7 mmHg) pressure gradient in the most severe case, evolving from 0.9 kPa (6.5 mmHg) from the healthy scenario. Finally, the pressure gradients were analysed using the base model, arriving at an extreme value of 1.04 W of destroyed exergy in the aortic valve and 9.64 W for the entire system, an increase of 22.6% when comparing with the result for the healthy condition.

© 2017 Elsevier LtdSome authors have been applying the exergy analysis to thermal comfort, where the environmental conditions for minimal exergy destruction are claimed to correspond to thermal comfort conditions. Herein, the exergy destroyed rate of the human body will be determined as a function of temperature and humidity for three levels of exercise. For the sake of comparison, thermal comfort will also be assessed by means of PMV (Predicted Mean Vote) index. Results indicate that, the higher the relative humidity, the lower the temperature of thermal comfort and, for the same humidity, the higher the exercise intensity, the smaller the temperature of thermal comfort. On the other hand, the values of PMV do not vary much with relative humidity, what indicates that the effect of this parameter is almost neglected by this method. Besides, the difference between the three levels of exercise was not as pronounced as in the exergy method. During activity, the values of the exergy flow rate due to evaporation for thermal comfort are smaller in the exergy method than in the conventional one. Thus, it can be said that, under physical activities, the exergy method for thermal comfort seems to be a reliable alternative to the conventional one.

© 2016 Elsevier LtdA precedent study about the effects of obesity on exergy behavior concluded that higher body fat per se does not lead to higher mortality among obese people; the focus must be turned to obesity-related diseases. Therefore, the next step towards the understanding of the effects of pathologies on the exergy behavior of human body is to analyze human heart. In the present work, an exergy model of human heart is developed. The heart is divided into two control volumes: the left heart, which pumps arterial blood from the lungs to the organs, and the right heart, which pumps venous blood from the organs to the lungs. Exergy of metabolism, exergy transfer associated to heat of metabolism, difference of exergy of blood flows and performed work are taken into account in the exergy balance for normotensive and hypertensive people under different levels of exercise. The left part of the heart is always responsible for more than 80% of the total exergy destruction. Moreover, a hypertensive heart destroys more exergy; this surplus value, when integrated along life cycle, represents 170 MJ/kg of destroyed exergy, which, according to the rate of living theory, would lead to a loss of 4.4 years in life expectancy.

© 2016 University of Ljubljana.Arteries can be compared to industrial pipes, being also susceptible to local pressure drops that may occur due to narrowing of the artery at some point, which is called stenosis. This phenomenon is taken as a singularity in the blood flow that leads to a localized head loss and, consequently, irreversibilities. In the present work, the exergy destruction in a given artery due to a stenosis is determined as a function of the diameter reduction taking into account the exergy variation of the flow between the inlet and the outlet, caused by distributed and localized head losses. The contribution of the stenosis is determined based on experimental results available in the literature. Arteries located in four different segments of the body are evaluated: trunk, leg, arm and neck. From the results, it can be noted that the effect of the severity of the stenosis is more pronounced for reductions higher than 55%. From this point on, the exergy destruction increases exponentially. It is also observed that, despite showing different behaviors for individual parcels, the total destroyed exergy rate of stenotic arteries of the leg and the trunk are very similar for high severities. Meanwhile, the arm presents the lowest values. About the contribution of the stenosis to the total destroyed exergy, the segment less susceptible was the trunk. When the specific destroyed exergy due to the stenosis is analyzed, it becomes clearer the impact of the mass flow rate. In this case, the highest values are obtained in the leg, followed by the neck, the trunk and the arm.

© 2015 Elsevier Ltd.According to literature, therapeutic hypothermia has been applied for treating conditions that causes an interruption in the delivery of oxygen to the brain, giving the patient better chances of survival with a neurological recovery and without any irreversible damage to the brain. Hypothermia is also used during surgeries and circulatory arrest. In this article, the objective temperature of hypothermia is 32°C, which is considered mild: 32-35°C. Three techniques of hypothermia induction were considered: external blood cooling, endovascular cooling with a catheter insertion and water bath. Energy and exergy analyses were performed to determine the clinical effectiveness of these techniques and to evaluate the best test parameters, from which it was possible to calculate the body internal temperature, destroyed exergy and exergy efficiency. Moreover, it was proposed an exergy performance index, which takes into account the ability of a given technique to change the exergy of the body. Results indicate that therapeutic hypothermia takes the subject to a state of lower destroyed exergy and higher body exergy efficiency. The exergy performance index shows that lower rates of cooling lead to a better transformation of the exergy removed from the body into variation of the body exergy.

In the past few years, exergy analysis has been applied to human body in order to understand its exergy behavior aiming at, ultimately, collaborating with medical area, by means of diagnosis and treatment of pathologies. Exergy behavior of human body as a whole has already been determined by few authors for standard and healthy subjects. A first attempt to study the effects of obesity on life expectancy by the light of exergy concepts has also been performed. However, this work came to the conclusion that higher body fat per se does not lead to higher mortality among obese people; the focus must be turned to obesity-related diseases, which are mostly related to impaired cardiovascular functions. Thus, the next step towards the comprehension of the effects of pathologies on exergy behavior of human body is to understand human heart by the exergy point of view. In the present work, an exergy model of human heart is developed. The heart is divided into two control volumes: left heart, which pumps arterial blood from the lungs to the organs, and right heart, which pumps venous blood from the organs to the lungs. In both left and right hearts, exergy metabolism, exergy transfer associated to heat of metabolism, difference of exergy of blood flows and performed work are taken into account. Exergy metabolism is determined from values of oxygen consumed and carbon dioxide produced by heart tissues available from thermal model of human body, which also provides the temperature of the heart, utilized to determine Carnot factor and, then, exergy transfer associated to heat metabolism, and partial pressures of oxygen and carbon dioxide in arterial and blood flows. Work performed by the heart is determined by means of pressure-volume diagrams. Then, it is possible to determine destroyed exergy and exergy efficiency of the heart at rest and also for walking and running. Moreover, these values can be confronted to those obtained for the whole body, estimating the percentage of destroyed exergy of the body that is attributed to the heart. The model can be applied to healthy subjects and also to individuals with hypertension or any other pathology that affects some input of the model.

The effect of altitude on exercise performance of lowlanders has long been discussed, but it is still unclear whether the performance reduction is related to inefficiency of the respiratory system, body tissues or both. In the present work, exergy analysis was applied to the human body in order to compare its exergy efficiency under basal conditions and during physical activity at sea level and high altitudes for different periods of acclimatization. Two control volumes were analyzed: respiratory system and human body as a whole. Data concerning mass and energy balances of the body and respiratory system were obtained from models available in the literature, which were modified based on medical literature to simulate the responses to physical activity at high altitude for different periods of acclimatization. The results indicated that the respiratory system exergy efficiency is reduced at high altitudes and under physical activity, while exergy efficiency of the body increases for both parameters, which may indicate that the discomfort reported at high altitudes is mostly related to the respiratory system than to the other ones. Concerning the acclimatization period, its influence was more pronounced on the respiratory system.

Therapeutic hypothermia is defined as the induction of a lowered core body temperature. Over the last decades it has been applied for treating conditions that lead to cell and tissue damage caused by ischemia, including traumatic brain injury, stroke and cardiac arrest giving the patient best chances of survival with a neurological recovery. It is also used during surgeries and circulatory arrest. In this article the temperature of hypothermia is 32°C, which is considered mild temperature (32-35°C). In this paper, three types of mild hypothermia induction were considered, among them: external blood cooling, catheter insertion and water bath. Hence, energy and exergy analysis is performed to determine the clinical effectiveness of this therapy and to evaluate the best tests parameters. To this aim, it is calculated the energy and exergy transfer to environment, the metabolism (on energy and exergy basis) and the body energy and exergy variation over time due to transient environmental conditions. From these results it is possible to calculate the internal temperature of the body (represented by the tympanic temperature), destroyed exergy and exergy efficiency. Moreover it is proposed an exergy indicator which takes into account the ability of a given technique to change the exergy of the body. Results indicate that therapeutic hypothermia takes the subject to a state of lower destroyed exergy and higher body exergy efficiency. In comparison with the other two techniques, the external blood cooling achieves core temperature closer to 32°C, with lower destroyed exergy and higher exergy efficiency. The exergy indicator shows that lower rates of cooling lead to a better transformation of the exergy removed from the body into variation of the body exergy.

Therapeutic hypothermia is defined as the induction of a lowered core body temperature. Over the last decades it has been applied for treating conditions that lead to cell and tissue damage caused by ischemia, including traumatic brain injury, stroke and cardiac arrest giving the patient best chances of survival with a neurological recovery. It is also used during surgeries and circulatory arrest. In this article the temperature of hypothermia is 32°C, which is considered mild temperature (32-35°C). In this paper, three types of mild hypothermia induction were considered, among them: external blood cooling, catheter insertion and water bath. Hence, energy and exergy analysis is performed to determine the clinical effectiveness of this therapy and to evaluate the best tests parameters. To this aim, it is calculated the energy and exergy transfer to environment, the metabolism (on energy and exergy basis) and the body energy and exergy variation over time due to transient environmental conditions. From these results it is possible to calculate the internal temperature of the body (represented by the tympanic temperature), destroyed exergy and exergy efficiency. Moreover it is proposed an exergy indicator which takes into account the ability of a given technique to change the exergy of the body. Results indicate that therapeutic hypothermia takes the subject to a state of lower destroyed exergy and higher body exergy efficiency. In comparison with the other two techniques, the external blood cooling achieves core temperature closer to 32°C, with lower destroyed exergy and higher exergy efficiency. The exergy indicator shows that lower rates of cooling lead to a better transformation of the exergy removed from the body into variation of the body exergy.

Exergy behavior of human body for standard and healthy subjects has already been determined by few authors, including estimative of life expectancy from values of generated entropy and destroyed exergy for different societies. Besides, an increase of obese population is being observed in modern society, as well as an increase of mortality rate among this population. In the present work, exergy analysis is applied to human body in order to evaluate the effect of obesity on exergy behavior of the body and to estimate life expectancy by means of an index called exergy age. The analysis takes into account exergy rates and flow rates due to convection, radiation, respiration, evaporation and exergy metabolism. A cylindrical model of human body divided into four layers is utilized. Three groups are evaluated: control (20% of body fat), moderately obese (30%) and obese (36%). Exergy destroyed rate is determined for the three biotypes along life cycle. By integrating its values overtime, it is observed that obese subjects destroy more exergy during their lives than lean ones. However, regarding total exergy destroyed per mass unit, which is claimed to have a maximum value during lifespan, exergy destruction is greater in control group. Determination of exergy age index indicates that life expectancy of moderately obese would be 8.4 years greater than lean subject, while obese subject would live 16.1 years more. When exergy efficiency and performed work are evaluated, it becomes clear that, on exergy basis, an obese body is less efficient than a lean one, destroying more exergy to perform the same amount of work. Present results indicate that obesity jeopardizes exergy behavior of human body, turning it into a less efficient apparatus, what may lead to development of the so-called obesity-related diseases.

The effect of altitude on exercise performance of lowlanders has long been discussed, but it is still unclear whether the performance reduction is related to inefficiency of the respiratory system, tissues or both. In the present work, exergy analysis was applied to the human body in order to compare its exergy efficiency under basal conditions and during physical activity at sea level and high altitudes for different periods of acclimatization. Two control volumes were analyzed: the respiratory system, which comprises the lungs and the airways, and the human body as a whole. In the first control volume, the exergy rates and flow rates are associated with the venous blood and the inspired air in the inlet and the arterial blood and expired air in the outlet. An internal exergy variation due to the exergy metabolism of the lung, an exergy transfer rate associated with the metabolism of the lung and the power performed by the respiratory muscles were also taken into account. Analyzing the second control volume, the exergy transferred rate to the environment due to the heat losses by convection and radiation were considered, as well as the exergy flow rate associated with respiration and transpiration. The temperatures of different parts of the body and the heat losses to the environment were obtained from a heat transfer model of the human body. The data concerning gas and blood flows were obtained from a model of the respiratory system. The last one was modified based on medical literature to simulate the response to physical activity at high altitude for different periods of acclimatization, from the first moment that the body is exposed to a high altitude environment to three months of acclimatization. The results obtained indicated that the respiratory system exergy efficiency is reduced at high altitudes and under physical activity, while the exergy efficiency of the body increases for both parameters. Concerning the acclimatization period, its influence was more pronounced in the respiratory system. It was possible to observe a decrease in the exergy efficiency of the respiratory system in the first two days. From this moment on, the efficiency increased continuously until the twentieth day, when it is stabilized and remains constant.