Performance Evaluation of the Thermophotovoltaic-Driven Thermoionic Refrigerator

2019 ◽  
Vol 142 (3) ◽  
Author(s):  
Emin Açıkkalp ◽  
Süheyla Yerel Kandemir ◽  
Mohammad H. Ahmadi
Keyword(s):  
Energy Source ◽  
Performance Evaluation ◽  
Solar Energy ◽  
Cooling Rate ◽  
Power Output ◽  
Exergy Efficiency ◽  
Exergy Destruction ◽  
Destruction Rate ◽  
Operation Conditions

Abstract In this study, the thermophotovoltaic (TPV)-driven thermionic refrigerator (TIR) is presented as an alternative refrigerator operated by the solar energy. Solar energy is the main energy source and its performance is analyzed. Power output density of the TPV, cooling rate density, COP, exergy destruction rate densities, and exergy efficiencies are the considered parameters. Calculations are performed numerically; results are presented and discussed. The most suitable operation conditions are defined. According to the results, the cooling rate density is 648 W/m2, power output densities are 1189.86 W/m2 and 667.234 W/m2 for the eg = 0.3 eV and eg = 0.4 eV, and the exergy efficiency of the system is about 0.071.

scholarly journals Evaluation and Optimization of the Annual Performance of a Novel Tri-Generation System Driven by Geothermal Brine in Off-Design Conditions

2020 ◽  
Vol 10 (18) ◽  
pp. 6532
Author(s):  
Mehri Akbari Kordlar ◽  
Florian Heberle ◽  
Dieter Brüggemann
Keyword(s):  
Exergy Efficiency ◽  
Working Fluid ◽  
Exergy Destruction ◽  
Operational Parameters ◽  
Generation System ◽  
Geothermal Resources ◽  
Kalina Cycle ◽  
Destruction Rate ◽  
Heating And Cooling ◽  
The Difference

The difference in heating or cooling to power ratio between required demands for district networks and the proposed tri-generation system is the most challenging issue of the system configuration and design. In this work, an adjustable, novel tri-generation system driven by geothermal resources is proposed to supply the thermal energies of a specific district network depending on ambient temperature in Germany. The tri-generation system is a combination of a modified absorption refrigeration cycle and a Kalina cycle using NH3-H2O mixture as a working fluid for the whole tri-generation system. A sensitive analysis of off-design conditions is carried out to study the effect of operational parameters on the system performances prior to optimizing its performance. The simulation show that the system is able to cover required heating and cooling demands. The optimization is applied considering the maximum exergy efficiency (scenario 1) and minimum total exergy destruction rate (scenario 2). The optimization results show that the maximum mean exergy efficiency in scenario 1 is achieved as 44.67% at the expense of 14.52% increase in the total exergy destruction rate in scenario 2. The minimum mean total exergy destruction rate in scenario 2 is calculated as 2980 kW at the expense of 8.32% decrease in the exergy efficiency in scenario 1.

scholarly journals Models for optimum thermo-ecological criteria of actual thermal cycles

2013 ◽  
Vol 17 (3) ◽  
pp. 915-930 ◽  
Author(s):  
Emin Açikkalp
Keyword(s):  
Energy Source ◽  
Heat Pump ◽  
Power Output ◽  
Exergy Destruction ◽  
Thermal Cycles ◽  
Power Cycles ◽  
Thermodynamic Cycles ◽  
Laws Of Thermodynamics ◽  
Ecological Criteria ◽  
Ecological Optimization

In this study, the ecological optimization point of irreversible thermal cycles (refrigerator, heat pump and power cycles) was investigated. The importance of ecological optimization is to propose a way to use fuels and energy source more efficiently because of an increasing energy need and environmental pollution. It provides this by maximizing obtained (or minimizing supplied) work and minimizing entropy generation for irreversible (actual) thermal cycles. In this research, ecological optimization was defined for all basic irreversible thermal cycles, by using the first and second laws of thermodynamics. Finally, the ecological optimization was defined in thermodynamic cycles and results were given to show the effects of the cycles? ecological optimization point, efficiency, COP and power output (or input), and exergy destruction.

scholarly journals Analysis and implementation of a solar tracking rack system

2020 ◽  
Vol 39 (3) ◽  
pp. 871-886 ◽  
Author(s):  
A.A. Okandeji ◽  
M.B. Olajide ◽  
G.O. Olasunkanmi ◽  
Z.O. Jagun
Keyword(s):  
Energy Source ◽  
Renewable Energy ◽  
Solar Energy ◽  
Power Output ◽  
Fundamental Problem ◽  
Tracking System ◽  
Experimental Result ◽  
Available Energy ◽  
Solar Tracking ◽  
Result Show

Solar energy is the most feasible source of renewable energy especially in sun rich regions like Africa. In particular, electrically epileptic country like Nigeria with current power output of only about 3.5GW of energy has a relatively long sunny period for about 90% of the year, making Nigeria very rich in solar power. Maximally harnessing solar energy into usable electricity however, is still a fundamental problem as the existing models can harness only about 70% of the available energy. To maximally harness solar energy, a solar panel must be perpendicular to the energy source for all 12hours of sunlight availability, and must be able to follow the sun’s movement all day long. Accordingly, this work considers the analysis, construction, and implementation of a single axis solar tracking dynamic system. Experimental result show that the proposed system outperforms the conventional static solar tracking system. Keywords: solar energy, single axis, harvesting-solar energy.

scholarly journals Performance Analysis of Multipurpose Refrigeration System (MRS) on Fishing Vessel

2016 ◽  
Vol 23 (2) ◽  
pp. 48-56 ◽  
Author(s):  
Y. Ust ◽  
A. Sinan Karakurt ◽  
U. Gunes
Keyword(s):  
Performance Analysis ◽  
Loss Rate ◽  
Industrial Applications ◽  
Exergy Efficiency ◽  
Coefficient Of Performance ◽  
Exergy Destruction ◽  
Parallel Operation ◽  
Refrigeration System ◽  
Energy Saving Potential ◽  
Operation Conditions

Abstract The use of efficient refrigerator/freezers helps considerably to reduce the amount of the emitted greenhouse gas. A two-circuit refrigerator-freezer cycle (RF) reveals a higher energy saving potential than a conventional cycle with a single loop of serial evaporators, owing to pressure drop in each evaporator during refrigeration operation and low compression ratio. Therefore, several industrial applications and fish storage systems have been utilized by using multipurpose refrigeration cycle. That is why a theoretical performance analysis based on the exergetic performance coefficient, coefficient of performance (COP), exergy efficiency and exergy destruction ratio criteria, has been carried out for a multipurpose refrigeration system by using different refrigerants in serial and parallel operation conditions. The exergetic performance coefficient criterion is defined as the ratio of exergy output to the total exergy destruction rate (or loss rate of availability). According to the results of the study, the refrigerant R32 shows the best performance in terms of exergetic performance coefficient, COP, exergy efficiency, and exergy destruction ratio from among the other refrigerants (R1234yf, R1234ze, R404A, R407C, R410A, R143A and R502). The effects of the condenser, freezer-evaporator and refrigerator-evaporator temperatures on the exergetic performance coefficient, COP, exergy efficiency and exergy destruction ratios have been fully analyzed for the refrigerant R32.

scholarly journals Performance Characteristics of Automobile Air Conditioning Using the R134a/R1234yf Mixture

Entropy ◽  
2019 ◽  
Vol 22 (1) ◽  
pp. 4
Author(s):  
Yunchan Shin ◽  
Taejung Kim ◽  
Areum Lee ◽  
Honghyun Cho
Keyword(s):  
Air Temperature ◽  
Cooling Capacity ◽  
Exergy Efficiency ◽  
Coefficient Of Performance ◽  
Exergy Destruction ◽  
Refrigeration System ◽  
Outdoor Air ◽  
Rotating Speed ◽  
Destruction Rate ◽  
Energy And Exergy

In this study, the energy and exergy of an automobile refrigeration system using R134a and R134a/R1234yf were analyzed experimentally with respect to outdoor air temperature and compressor speed. As outdoor air temperature increased from 32.5 °C to 37.5 °C, the coefficient of performance (COP) and total exergy destruction rate of the refrigeration system using Mix30 decreased by 5.19% and 25.8% on average, compared to that of the system using R134a. The exergy efficiency of the Mix30 refrigeration system was on average 21.8% higher than that of the R134a system. As the compressor rotating speed increased from 1000 to 2000 rpm, the cooling capacity of the refrigeration system using R134a and R134a/R1234yf increased, while the COP decreased. The COP and total exergy destruction rate of the refrigeration system using Mix30 decreased by 4.82% and 19.5%, compared to that of the system using R134a. The exergy efficiency of the Mix30 refrigeration system increased on average by 20.7%, compared to that of the R134a system. The total exergy destruction rate of the automobile refrigeration system using R134a/R1234yf decreased with increase in R1234yf, while exergy efficiency increased. In addition, the exergy destruction rate of the automobile refrigeration system decreased as the amount of R1234yf in the R134a/R1234yf automobile refrigeration system increased.

scholarly journals Exergy efficiency of thermochemical syngas-to-ethanol production plants

2021 ◽  
Vol 3 (5) ◽  
Author(s):  
Marcos Paulo Gabriel da Costa e Silva ◽  
Júlio Cesar de Carvalho Miranda
Keyword(s):  
Ethanol Production ◽  
Process Improvement ◽  
Second Generation ◽  
Exergy Efficiency ◽  
Exergy Destruction ◽  
Exothermic Reactions ◽  
Production Processes ◽  
Different Temperatures ◽  
Exergy Analyses ◽  
Second Generation Ethanol

Abstract This work presents exergy analyses applied in four different conceptual second-generation ethanol production processes through a thermochemical route using catalysts based on Molybdenum (P-1), Copper (P-2), and Rhodium (P-3 and P-4), aiming to assess their exergetic efficiencies. The results show that the conceptual processes have satisfactory exergy efficiencies in both cases, when compared among themselves and when compared with other processes reported in literature. The processes’ efficiency for P-1, P-2, P-3 and P-4 were, respectively, 52.4%, 41.4%, 43.7% and 48.9%. The reactors were the sections in which exergy destruction was more significant, due to the exothermic reactions and mixing points (where streams with different temperatures were mixed). Such results show the potential of thermochemical ethanol production, besides opening the possibilities of process improvement. Graphic abstract

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%).

scholarly journals Predicting the Performance of Solar Power Generation Using Deep Learning Methods

2021 ◽  
Vol 11 (15) ◽  
pp. 6887
Author(s):  
Chung-Hong Lee ◽  
Hsin-Chang Yang ◽  
Guan-Bo Ye
Keyword(s):  
Power Generation ◽  
Solar Energy ◽  
Power Output ◽  
Power Plants ◽  
Solar Power ◽  
Photovoltaic Cell ◽  
Power Prediction ◽  
Seasonal Characteristics ◽  
Variable Nature ◽  
Solar Power Plants

In recent years, many countries have provided promotion policies related to renewable energy in order to take advantage of the environmental factors of sufficient sunlight. However, the application of solar energy in the power grid also has disadvantages. The most obvious is the variability of power output, which will put pressure on the system. As more grid reserves are needed to compensate for fluctuations in power output, the variable nature of solar power may hinder further deployment. Besides, one of the main issues surrounding solar energy is the variability and unpredictability of sunlight. If it is cloudy or covered by clouds during the day, the photovoltaic cell cannot produce satisfactory electricity. How to collect relevant factors (variables) and data to make predictions so that the solar system can increase the power generation of solar power plants is an important topic that every solar supplier is constantly thinking about. The view is taken, therefore, in this work, we utilized the historical monitoring data collected by the ground-connected solar power plants to predict the power generation, using daily characteristics (24 h) to replace the usual seasonal characteristics (365 days) as the experimental basis. Further, we implemented daily numerical prediction of the whole-point power generation. The preliminary experimental evaluations demonstrate that our developed method is sensible, allowing for exploring the performance of solar power prediction.

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