scholarly journals Analysis of Operation Parameters of Fish Refrigeration by Exergy Analysis. Case Study

2019 ◽  
Vol 23 (1) ◽  
pp. 229-241
Author(s):  
Edvins Terehovics ◽  
Ivars Veidenbergs ◽  
Dagnija Blumberga
Keyword(s):  
Energy Efficiency ◽  
Ambient Temperature ◽  
Working Conditions ◽  
Temperature Difference ◽  
Exergy Analysis ◽  
Exergy Efficiency ◽  
Single Stage ◽  
Exergy Destruction ◽  
Refrigeration System ◽  
The Ideal

Abstract Unlike energy efficiency, in terms of exergy efficiency it is possible to compare the existing operation of an energy conversion system with the ideal operation. Exergy loses and exergy destruction make it possible to identify the shortcomings of an existing system, which should be improved immediately. With exergy analysis, it is possible to identify the priority actions that need to be taken in order to improve the functioning of the system: greater exergy loss prevention is the highest priority. Energy efficiency refers to the useful work and investments needed to obtain useful work and investments needed to obtain energy efficiency; this is important to some extent, but the effectiveness of exergy makes it possible to compare system performance with the ideal. Results shows that the highest exergy destruction of a single-stage compressor refrigeration system from all working condition is found when ambient temperature and freezer temperature difference is 10 ºC, pressure in compressor is 0.62 MPa, ammonia temperature after compressor is 90 ºC, total exergy destruction of single-stage compressor refrigeration system 97.84 kW. The highest exergy efficiency of a single-stage compressor refrigeration system from all the working conditions is found when ambient temperature and freezer temperature difference is 39 ºC, pressure in compressor is 0.45 MPa, ammonia temperature after compressor is 128 ºC, exergy efficiency of a single-stage compressor refrigeration system is 59.76 %. The highest total exergy destruction of a two-stage compressor refrigeration system from among all the working conditions is found to be when the ambient temperature and freezer temperature difference is at 13 ºC, pressure in compressor 0.44 MPa, ammonia temperature after compressor 76 ºC, total exergy destruction 83.86 kW. The highest exergy efficiency of a two-stage compressor refrigeration system from among all the working conditions is found to be at an ambient temperature and freezer temperature difference of 39 ºC, pressure in compressor 0.56 MPa, ammonia temperature after compressor 92 ºC, exergy efficiency 53.55 %.

scholarly journals Exergy Analysis of 1 x 135 MW Jeneponto Steam Power Plant

2021 ◽  
Vol 7 (2) ◽  
pp. 150
Author(s):  
Nur Hamzah ◽  
A.M Shiddiq Yunus ◽  
Waqva Enno Al Fadiyah
Keyword(s):  
Power Plant ◽  
Ambient Temperature ◽  
Exergy Analysis ◽  
Exergy Efficiency ◽  
Second Law ◽  
Exergy Destruction ◽  
Steam Power ◽  
Total Destruction ◽  
Destruction Efficiency ◽  
Mass Flowrate

Exergy analysis is application of the second law thermodynamics which provides information about large exergy, exergy efficiency, destruction, and destruction efficiency in each component of PLTU so can be reference for improvement and optimization in an effort to reduce losses and increase efficiency. The exergy value obtained from calculating mass flowrate, enthalpy, ambient temperature, and entropy. The destruction value is obtained from difference between input exergy value and exergy output. The destruction exergy value from comparison between output exergy value to input exergy value, and destruction efficiency value from comparison of destruction value to total destruction value of PLTU components. The results showed that the largest exergy occurred in boilers, namely 778.225 MW in 2018, 788.824 MW in 2019, and 796.824 MW in 2020, lowest exergy value in CP was 0.160 MW in 2018, 0.176 MW in 2019, and 0.160 MW in 2020. The largest destruction occurred in boilers, namely 163.970 MW with destruction efficiency 79.242% in 2018, 179.450 MW with destruction efficiency 82.111% in 2019, and 199.637 MW with destruction efficiency 83.448% in 2020, lowest exergy destruction value at CP, namely 0.056 MW with destruction efficiency 0.027% in 2018, 0.059 MW with destruction efficiency 0.027% in 2019, and 0.056 MW with destruction efficiency 0.023% in 2020. The exergy efficiency occurred in HPH 2, amounting to 94.750% in 2018, 95.187 % in 2019, and 94.728% in 2020, while lowest of exergy efficiency was in LPH 1, namely 43.637 MW in 2018, 33.512 MW in 2019, and 38.764 MW in 2020.

EXERGY ANALYSIS OF GEOTHERMAL POWER PLANT KAMOJANG 68, 3 MW IN CAPACITY

2018 ◽  
Vol 7 (2) ◽  
Author(s):  
Amiral Aziz
Keyword(s):  
Energy Efficiency ◽  
Power Plant ◽  
Exergy Analysis ◽  
Exergy Efficiency ◽  
Preliminary Design ◽  
Exergy Destruction ◽  
Geothermal Power Plant ◽  
Production Wells ◽  
Geothermal Power ◽  
Exergy Losses

The importance of exergy analysis in preliminary design of geothermal power has been proven. An exergy analysis was carried out and the locations and quantities of exergy losses, wastes and destructions in the different processes of the plan were pinpointed. The obtained results show that the total exergy available from production wells KMJ 68 was calculated to be 6967.55 kW. The total exergy received from wells which is connected during the analysis and enter into the separator was found to be 6337.91 kW in which 5808.8 kW is contained in the steam phase. The overall exergy efficiency for the power plant is 43.06% and the overall energy efficiency is 13.05 %, in both cases with respect to the exergy from the connected wells. The parts of the system with largest exergy destruction are the condenser, the turbine, and the disposed waste brinekeywords: exergy, irreversibility, geothermal power plant, KMJ 68

Thermodynamic modeling and Exergy Analysis of Gas Turbine Cycle for Different Boundary conditions

2015 ◽  
Vol 6 (2) ◽  
pp. 205 ◽  
Author(s):  
Lalatendu Pattanayak
Keyword(s):  
Ambient Temperature ◽  
Combustion Chamber ◽  
Gas Turbine ◽  
Exergy Analysis ◽  
Load Condition ◽  
Exergy Efficiency ◽  
Inlet Temperature ◽  
Exergy Destruction ◽  
And Performance ◽  
Topping Cycle

In this study an exergy analysis of 88.71 MW 13D2 gas turbine (GT) topping cycle is carried out. Exergy analysis based on second law was applied to the gas cycle and individual components through a modeling approach. The analysis shows that the highest exergy destruction occurs in the combustion chamber (CC). In addition, the effects of the gas turbine load and performance variations with ambient temperature, compression ratio and turbine inlet temperature (TIT) are investigated to analyse the change in system behavior. The analysis shows that the gas turbine is significantly affected by the ambient temperature which leads to a decrease in power output. The results of the load variation of the gas turbine show that a reduction in gas turbine load results in a decrease in the exergy efficiency of the cycle as well as all the components. The compressor has the largest exergy efficiency of 92.84% compared to the other component of the GT and combustion chamber is the highest source of exergy destruction of 109.89 MW at 100 % load condition. With increase in ambient temperature both exergy destruction rate and exergy efficiency decreases.

scholarly journals Performance Evaluation of a Full-Scale Fused Magnesia Furnace for MgO Production Based on Energy and Exergy Analysis

Energies ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 214
Author(s):  
Tianchi Jiang ◽  
Weijun Zhang ◽  
Shi Liu
Keyword(s):  
Energy Efficiency ◽  
Mass Transport ◽  
Exergy Analysis ◽  
Exergy Efficiency ◽  
Smelting Process ◽  
Exergy Destruction ◽  
Electric Power Supply ◽  
Flow Energy ◽  
Energy And Exergy ◽  
Energy And Exergy Analysis

A three-electrode alternating current fused magnesia furnace (AFMF) with advanced control technology was evaluated by combined energy and exergy analysis. To gain insight into the mass flow, energy flow and exergy efficiency of the present fused magnesia furnace, the exergy destruction was analysed to study the energy irreversibility of the furnace. Two different production processes, the magnesite ore smelting process (MOP) and light-calcined magnesia process (LMP), are discussed separately. Two methods were carried out to improve LMP and MOP; one of which has been applied in factories. The equipment consists of an electric power supply system, a light-calcined system and a three-electrode fused magnesia furnace. All parameters were tested or calculated based on the data investigated in industrial factories. The calculation results showed that for LMP and MOP, the mass transport efficiencies were 16.6% and 38.3%, the energy efficiencies were 62.2% and 65.5%, and the exergy destructions were 70.5% and 48.4%, respectively. Additionally, the energy efficiency and exergy efficiency of the preparation process of LMP were 39.4% and 35.6%, respectively. After the production system was improved, the mass transport efficiency, energy efficiency and exergy destruction were determined.

scholarly journals Performance Optimizations of the Transcritical CO2 Two-Stage Compression Refrigeration System and Influences of the Auxiliary Gas Cooler

Energies ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5578
Author(s):  
Yuyao Sun ◽  
Jinfeng Wang ◽  
Jing Xie
Keyword(s):  
Exergy Analysis ◽  
Energy Analysis ◽  
Exergy Efficiency ◽  
Exergy Destruction ◽  
Refrigeration System ◽  
System Operation ◽  
Two Stage ◽  
Intermediate Pressure ◽  
Discharge Temperature ◽  
Performance Optimizations

To optimize the performance of the transcritical CO2 two-stage compression refrigeration system, the energy analysis and the exergy analysis are conducted. It is found that higher COP, lower compression power, and less exergy destruction can be achieved when the auxiliary gas cooler is applied. Moreover, the discharge temperature of the compound compressor (HPS) can be reduced by decreasing the temperature at the outlet of the auxiliary gas cooler (Tagc,out). When the Tagc,out is reduced from 30 to 12 ℃, the discharge temperature of the compound compressor (HPS) can be decreased by 13.83 ℃. Furthermore, the COP and the exergy efficiency can be raised by enhancing the intermediate pressure. Based on these results, the optimizations of system design and system operation are put forward. The application of the auxiliary gas cooler can improve the performance of the transcritical CO2 two-stage compression refrigeration system. Operators can decrease the discharge temperature of the compound compressor (HPS) by reducing the Tagc,out, and increase the COP and the exergy efficiency by enhancing the intermediate pressure.

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 Exergy analysis of marine steam turbine labyrinth (gland) seals

Pomorstvo ◽  
2019 ◽  
Vol 33 (1) ◽  
pp. 76-83 ◽  
Author(s):  
Ivan Lorencin ◽  
Nikola Anđelić ◽  
Vedran Mrzljak ◽  
Zlatan Car
Keyword(s):  
Ambient Temperature ◽  
Steam Turbine ◽  
Exergy Analysis ◽  
Numerical Models ◽  
Operating Regime ◽  
Exergy Efficiency ◽  
Specific Enthalpy ◽  
Labyrinth Seals ◽  
Proper Operation ◽  
Operating Regimes

The paper presents an exergy analysis of marine steam turbine labyrinth (gland) seals - an inevitable component of any marine steam turbine cylinder, in three different operating regimes. Throughout labyrinth seals, steam specific enthalpy can be considered as a constant because the results obtained by this assumption do not deviate significantly from the results of complex numerical models. Changes in labyrinth seals exergy efficiency and specific exergy destruction are reverse proportional. The analyzed labyrinth seals have high exergy efficiencies in each observed operating regime at the ambient temperature of 298 K (above 92%), what indicates seals proper operation. An increase in the ambient temperature resulted with a decrease in labyrinth seals exergy efficiency, but even at the highest observed ambient temperature of 318 K, seals exergy efficiency did not fall below 90.5% in each observed operating regime.

scholarly journals Advanced Thermodynamic Analysis of a Transcritical R744 Booster Refrigerating Unit with Dedicated Mechanical Subcooling

Energies ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 3058 ◽  
Author(s):  
Paride Gullo
Keyword(s):  
Low Temperature ◽  
Thermodynamic Analysis ◽  
Temperature Difference ◽  
Exergy Analysis ◽  
Refrigeration System ◽  
Outdoor Temperature ◽  
Medium Temperature ◽  
High Stage ◽  
Thermodynamic Performance ◽  
Priority Needs

In this work the thermodynamic performance of a transcritical R744 booster supermarket refrigeration system equipped with R290 dedicated mechanical subcooling (DMS) was exhaustively investigated with the aid of the advanced exergy analysis. The outcomes obtained suggested that improvement priority needs to be addressed to the manufacturing of more efficient high-stage (HS) compressors, followed by the enhancement of the gas cooler/condenser (GC), of the medium-temperature (MT) evaporators, of the R290 compressor, and of the low-temperature (LT) evaporators. These conclusions were different from those drawn by the application of the conventional exergy assessment. Additionally, it was found that GC can be enhanced mainly by reducing the irreversibilities owing to the simultaneous interaction among the components. The R290 compressor would also have significantly benefitted from the adoption of such measures, as half of its avoidable irreversibilities were exogenous. Unlike the aforementioned components, all the evaporators were improvable uniquely by decreasing their temperature difference. Finally, the approach temperature of GC and the outdoor temperature were found to have a noteworthy impact on the avoidable irreversibilities of the investigated solution.

Analysis of a Combined Power and Refrigeration Cycle Working on Solar Energy

2008 ◽  
Author(s):  
Bijan Kumar Mandal ◽  
Kousik Sadhukhan ◽  
Achin Kumar Chowdhuri ◽  
Arup Jyoti Bhowal
Keyword(s):  
Solar Energy ◽  
Working Conditions ◽  
Exergy Efficiency ◽  
Combined Cycle ◽  
Cooling Effect ◽  
Second Law ◽  
Carnot Cycle ◽  
Refrigeration Cycle ◽  
Water Mixture ◽  
The Ideal

Thermodynamic analysis of a combined cycle producing power and refrigeration (cooling) effect simultaneously using solar energy has been analyzed. The working substance of the cycle is a binary mixture of ammonia and water. The effect of variation of absorber pressure, boiler pressure, boiler temperature and superheater temperature on the turbine work, refrigeration (cooling) effect and net output has been investigated. For different conditions of the above variables, the first law efficiency, the second law efficiency and the exergy efficiency of the cycle have been investigated. Since the ammonia water mixture boils at varying temperatures, Lorenz cycle instead of Carnot cycle is considered as the ideal cycle for this analysis. It is observed that the first law and the second law efficiencies are maximum under the same working conditions, but the exergy efficiency is maximum at some other working conditions. The maximum values of the first law, the second law and the exergy efficiencies are found to be 21.72%, 27.30% and 62.53% respectively.

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