scholarly journals Exergy Analysis of a Bio-System: Soil–Plant Interaction

Entropy ◽  
2020 ◽  
Vol 23 (1) ◽  
pp. 3
Author(s):  
Masoomeh Bararzadeh Ledari ◽  
Yadollah Saboohi ◽  
Antonio Valero ◽  
Sara Azamian
Keyword(s):  
Exergy Analysis ◽  
Second Law Of Thermodynamics ◽  
Formation Processes ◽  
Exergy Destruction ◽  
Prime Mover ◽  
Plant Interactions ◽  
Mineralization Process ◽  
Soil System ◽  
Biomass Storage ◽  
Low Efficiency

This paper explains a thorough exergy analysis of the most important reactions in soil–plant interactions. Soil, which is a prime mover of gases, metals, structural crystals, and electrolytes, constantly resembles an electric field of charge and discharge. The second law of thermodynamics reflects the deterioration of resources through the destruction of exergy. In this study, we developed a new method to assess the exergy of soil and plant formation processes. Depending on the types of soil, one may assess the efficiency and degradation of resources by incorporating or using biomass storage. According to the results of this study, during different processes from the mineralization process to nutrient uptake by the plant, about 62.5% of the input exergy will be destroyed because of the soil solution reactions. Most of the exergy destruction occurs in the biota–atmosphere subsystem, especially in the photosynthesis reaction, due to its low efficiency (about 15%). Humus and protonation reactions, with 14% and 13% exergy destruction, respectively, are the most exergy destroying reactions. Respiratory, weathering, and reverse weathering reactions account for the lowest percentage of exergy destruction and less than one percent of total exergy destruction in the soil system. The total exergy yield of the soil system is estimated at about 37.45%.

Exergy Analysis of a Solar Heating System

1995 ◽  
Vol 117 (3) ◽  
pp. 249-251 ◽  
Author(s):  
Geng Liu ◽  
Y. A. Cengel ◽  
R. H. Turner
Keyword(s):  
Exergy Analysis ◽  
Energy Analysis ◽  
Second Law Of Thermodynamics ◽  
Heating System ◽  
Solar Heating ◽  
Second Law ◽  
Exergy Destruction ◽  
Thermal Systems ◽  
Heating Systems ◽  
Second Law Analysis

Exergy destruction associated with the operation of a solar heating system is evaluated numerically via an exergy cascade. As expected, exergy destruction is dominated by heat transfer across temperature differences. An energy analysis is also given for comparison of exergy cascade to energy cascade. Efficiencies based on both the first law and second law of thermodynamics are calculated for a number of components and for the system. The results show that high first-law efficiency does not mean high second-law efficiency. Therefore, the second-law analysis has been proven to be a more powerful tool in identifying the site losses. The procedure used to determine total exergy destruction and second law efficiency can be used in a conceptual design and parametric study to evaluate the performance of other solar heating systems and other thermal systems.

scholarly journals Conventional and Advanced Exergoeconomic Analysis of a Compound Ejector-Heat Pump for Simultaneous Cooling and Heating

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3511
Author(s):  
Ali Khalid Shaker Al-Sayyab ◽  
Joaquín Navarro-Esbrí ◽  
Victor Manuel Soto-Francés ◽  
Adrián Mota-Babiloni
Keyword(s):  
Heat Pump ◽  
Exergy Analysis ◽  
Waste Heat ◽  
District Heating ◽  
Cost Comparison ◽  
Exergy Destruction ◽  
Pump System ◽  
Heat Pump System ◽  
Destruction Rate ◽  
Exergoeconomic Analysis

This work focused on a compound PV/T waste heat driven ejector-heat pump system for simultaneous data centre cooling and waste heat recovery for district heating. The system uses PV/T waste heat as the generator’s heat source, acting with the vapour generated in an evaporative condenser as the ejector drive force. Conventional and advanced exergy and advanced exergoeconomic analyses are used to determine the cause and avoidable degree of the components’ exergy destruction rate and cost rates. Regarding the conventional exergy analysis for the whole system, the compressor represents the largest exergy destruction source of 26%. On the other hand, the generator shows the lowest sources (2%). The advanced exergy analysis indicates that 59.4% of the whole system thermodynamical inefficiencies can be avoided by further design optimisation. The compressor has the highest contribution to the destruction in the avoidable exergy destruction rate (21%), followed by the ejector (18%) and condenser (8%). Moreover, the advanced exergoeconomic results prove that 51% of the system costs are unavoidable. In system components cost comparison, the highest cost comes from the condenser, 30%. In the same context, the ejector has the lowest exergoeconomic factor, and it should be getting more attention to reduce the irreversibility by design improving. On the contrary, the evaporator has the highest exergoeconomic factor (94%).

Energy and Exergy Analysis of the Teduction Zone in a Downdraft (Biomass) Gasifier

2010 ◽  
Vol 8 (1) ◽  
Author(s):  
Avdhesh Kr. Sharma ◽  
Raj Kumar Singh
Keyword(s):  
Kinetic Models ◽  
Exergy Analysis ◽  
Internal Heat ◽  
Calorific Value ◽  
Exergy Destruction ◽  
Reduction Zone ◽  
Reactor Performance ◽  
General Validity ◽  
Energy And Exergy ◽  
Energy And Exergy Analysis

This article describes the energy and exergy analysis of the reduction zone in a downdraft biomass gasifier. A simplistic formulation for describing the pyrolysis and oxidation of these products has been presented for initialization. Equilibrium and kinetic models are used to predict the reduction products leaving the reduction zone and thus the 1st law efficiency. In the reduction zone, exergy destruction due to chemical, physical, compositional, internal heat transfer and heat loss to the surrounding has been quantified to describe 2nd law efficiency. The comparison of equilibrium and kinetic models is carried out with experimental data for general validity. Parametric analysis of char bed length and inflow temperature on gas composition, un-converted char, exergy destruction, 1st law and the 2nd law efficiency has also been carried out. Simulation results identified a critical char bed length (where all char gets consumed) for a given feedstock, which depends on residence time and reaction temperature in the reduction zone. Near critical char bed length, predictions show high calorific value of gas with relatively less exergy destruction and thus optimum reactor performance. The accuracy of the prediction depends on the validity of initial input conditions.

Exergy Analysis of a Combined Power and Refrigeration Thermodynamic Cycle Driven by a Solar Heat Source

2003 ◽  
Vol 125 (1) ◽  
pp. 55-60 ◽  
Author(s):  
Afif Akel Hasan ◽  
D. Y. Goswami
Keyword(s):  
Heat Source ◽  
Exergy Analysis ◽  
Thermodynamic Cycle ◽  
Exergy Efficiency ◽  
Operating Conditions ◽  
Optimum Operating ◽  
Water Mixture ◽  
Exergy Destruction ◽  
Ammonia Water ◽  
Solar Heat

Exergy thermodynamics is employed to analyze a binary ammonia water mixture thermodynamic cycle that produces both power and refrigeration. The analysis includes exergy destruction for each component in the cycle as well as the first law and exergy efficiencies of the cycle. The optimum operating conditions are established by maximizing the cycle exergy efficiency for the case of a solar heat source. Performance of the cycle over a range of heat source temperatures of 320–460°K was investigated. It is found that increasing the heat source temperature does not necessarily produce higher exergy efficiency, as is the case for first law efficiency. The largest exergy destruction occurs in the absorber, while little exergy destruction takes place in the boiler.

scholarly journals Energy and Exergy Analysis of Sensible Thermal Energy Storage—Hot Water Tank for a Large CHP Plant in Poland

Energies ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4842 ◽  
Author(s):  
Ryszard Zwierzchowski ◽  
Marcin Wołowicz
Keyword(s):  
Energy Storage ◽  
Ambient Temperature ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Exergy Analysis ◽  
Hot Water ◽  
Water Tank ◽  
Exergy Destruction ◽  
Energy And Exergy ◽  
Energy And Exergy Analysis

The paper contains a simplified energy and exergy analysis of pumps and pipelines system integrated with Thermal Energy Storage (TES). The analysis was performed for a combined heat and power plant (CHP) supplying heat to the District Heating System (DHS). The energy and exergy efficiency for the Block Part of the Siekierki CHP Plant in Warsaw was estimated. CHP Plant Siekierki is the largest CHP plant in Poland and the second largest in Europe. The energy and exergy analysis was executed for the three different values of ambient temperature. It is according to operation of the plant in different seasons: winter season (the lowest ambient temperature Tex = −20 °C, i.e., design point conditions), the intermediate season (average ambient temperature Tex = 1 °C), and summer (average ambient temperature Tex = 15 °C). The presented results of the analysis make it possible to identify the places of the greatest exergy destruction in the pumps and pipelines system with TES, and thus give the opportunity to take necessary improvement actions. Detailed results of the energy-exergy analysis show that both the energy consumption and the rate of exergy destruction in relation to the operation of the pumps and pipelines system of the CHP plant with TES for the tank charging and discharging processes are low.

scholarly journals Optimal and Decentralized Control Strategies for Inverter-Based AC Microgrids

Energies ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 3529 ◽  
Author(s):  
Michael D. Cook ◽  
Eddy H. Trinklein ◽  
Gordon G. Parker ◽  
Rush D. Robinett ◽  
Wayne W. Weaver
Keyword(s):  
Decentralized Control ◽  
Closed Loop ◽  
Exergy Analysis ◽  
Control Strategies ◽  
Distributed Storage ◽  
Droop Control ◽  
Exergy Destruction ◽  
High Penetration ◽  
Feedforward Controller ◽  
Fully Connected

This paper presents two control strategies: (i) An optimal exergy destruction (OXD) controller and (ii) a decentralized power apportionment (DPA) controller. The OXD controller is an analytical, closed-loop optimal feedforward controller developed utilizing exergy analysis to minimize exergy destruction in an AC inverter microgrid. The OXD controller requires a star or fully connected topology, whereas the DPA operates with no communication among the inverters. The DPA presents a viable alternative to conventional P − ω / Q − V droop control, and does not suffer from fluctuations in bus frequency or steady-state voltage while taking advantage of distributed storage assets necessary for the high penetration of renewable sources. The performances of OXD-, DPA-, and P − ω / Q − V droop-controlled microgrids are compared by simulation.

Energy and Exergy Analysis of Gasifier-Based Coal-to-Fuel Systems

2010 ◽  
Vol 132 (2) ◽  
Author(s):  
Yunhua Zhu ◽  
Sriram Somasundaram ◽  
James W. Kemp
Keyword(s):  
Exergy Analysis ◽  
High Efficiency ◽  
Second Law Of Thermodynamics ◽  
Conservation Of Energy ◽  
Transportation Fuels ◽  
Synthetic Natural Gas ◽  
Entrained Flow ◽  
Technology Improvement ◽  
Entrained Flow Gasifier ◽  
Construction Operation

National energy security concerns related to liquid transportation fuels have revived interests in alternative liquid fuel sources. Coal-to-fuel technologies feature high efficiency energy conversion and environmental advantages. While a number of factors are driving coal-to-fuel projects forward, there are several barriers to wide commercialization of these technologies such as financial, construction, operation, and technical risks. The purpose of this study is to investigate the performance features of coal-to-fuel systems based on different gasification technologies. The target products are the Fischer–Tropsch synthetic crude and synthetic natural gas. Two types of entrained-flow gasifier-based coal-to-fuel systems are simulated and their performance features are discussed. One is a single-stage water quench cooling entrained-flow gasifier, and another one is a two-stage syngas cooling entrained-flow gasifier. The conservation of energy (first law of thermodynamics) and the quality of energy (second law of thermodynamics) for the systems are both investigated. The results of exergy analysis provide insights about the potential targets for technology improvement. The features of different gasifier-based coal-to-fuel systems are discussed. The results provide information about the research and development priorities in future.

Exergy Analysis of Part Flow Evaporative Gas Turbine Cycles: Part 2 — Results and Discussion

2002 ◽  
Author(s):  
Maria Jonsson ◽  
Jinyue Yan
Keyword(s):  
Gas Turbine ◽  
Heat Recovery ◽  
Exergy Analysis ◽  
Compressed Air ◽  
Cycle Performance ◽  
Exergy Destruction ◽  
Exergetic Efficiency ◽  
Recovery System ◽  
Heat Recovery System ◽  
Flow Case

This paper is the second part of a two-part paper. The first part contains an introduction to the evaporative gas turbine (EvGT) cycle and the methods used in the study. The second part contains the results, discussion, and conclusions. In this study, exergy analysis of EvGT cycles with part flow humidification based on the industrial GTX100 and the aeroderivative Trent has been performed. In part flow EvGT cycles, only a fraction of the compressed air is passed through the humidification system. The paper presents and analyzes the exergetic efficiencies of the components of both gas turbine cycles. The highest cycle exergetic efficiencies were found for the full flow case for the GTX100 cycles and for the 20% part flow case for the Trent cycles. The largest exergy destruction occurs in the combustor, and the exergetic efficiency of this component has a large influence on the overall cycle performance. The exergy destruction of the heat recovery system is low.

scholarly journals Energy and Exergy Analysis of Combined Organic Rankine Cycle-Single and Dual Evaporator Vapor Compression Refrigeration Cycle

2019 ◽  
Vol 9 (23) ◽  
pp. 5028 ◽  
Author(s):  
Pektezel ◽  
Acar
Keyword(s):  
Exergy Analysis ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Working Fluid ◽  
Refrigeration Cycle ◽  
Vapor Compression ◽  
Exergy Destruction ◽  
Energy And Exergy ◽  
Energy And Exergy Analysis ◽  
Vapor Compression Refrigeration

This paper presents energy and exergy analysis of two vapor compression refrigeration cycles powered by organic Rankine cycle. Refrigeration cycle of combined system was designed with single and dual evaporators. R134a, R1234ze(E), R227ea, and R600a fluids were used as working fluids in combined systems. Influences of different parameters such as evaporator, condenser, boiler temperatures, and turbine and compressor isentropic efficiencies on COPsys and ƞex,sys were analyzed. Second law efficiency, degree of thermodynamic perfection, exergy destruction rate, and exergy destruction ratio were detected for each component in systems. R600a was determined as the most efficient working fluid for proposed systems. Both COPsys and ƞex,sys of combined ORC-single evaporator VCR cycle was detected to be higher than the system with dual evaporator.

Exergy analysis and nanoparticle assessment of cooking oil biodiesel and standard diesel fueled internal combustion engine

2019 ◽  
Vol 31 (8) ◽  
pp. 1303-1317 ◽  
Author(s):  
Ibrahim Yildiz ◽  
Hakan Caliskan ◽  
Kazutoshi Mori
Keyword(s):  
Carbon Monoxide ◽  
Particle Concentration ◽  
Exergy Analysis ◽  
Combustion Engine ◽  
Environmentally Benign ◽  
Hydrocarbon Emissions ◽  
Exergy Destruction ◽  
Environmental Assessments ◽  
Cooking Oil ◽  
Japanese Industrial Standard

In this paper, the exergy analysis and environmental assessment are performed to the biodiesel and diesel-fueled engine at full 294 Nm and 1800 r/min. The exergy loss rates of fuels are found as 15.523 and 18.884 kW for the 100% biodiesel (BDF100) (obtained from cooking oil) and Japanese Industrial Standard Diesel No. 2 (JIS#2) fuels, respectively. In addition, the exergy destruction rate of the JIS#2 fuel is found as 80.670 kW, while the corresponding rate of the BDF100 is determined as 62.389 kW. According to environmental assessments of emissions and nanoparticles of the fuels, the biodiesel (BDF100) fuel is more environmentally benign than the diesel (JIS#2) fuel in terms of particle concentration and carbon monoxide and hydrocarbon emissions. So, it is better to use this kind of the 100% biodiesels in the diesel engines for better environment and efficiency in terms of the availability and environmental perspectives.

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