scholarly journals Endoreversible Trigeneration Cycle Design Based on Finite Physical Dimensions Thermodynamics

Energies ◽  
2019 ◽  
Vol 12 (16) ◽  
pp. 3165 ◽  
Author(s):  
Dumitrascu Gheorghe ◽  
Feidt Michel ◽  
Popescu Aristotel ◽  
Grigorean Stefan
Keyword(s):  
Winter Season ◽  
Thermal Conductance ◽  
Systems Design ◽  
Heat Sources ◽  
Operational Parameters ◽  
Heating Rates ◽  
External Energy ◽  
Working Fluids ◽  
Energy And Exergy ◽  
Physical Dimensions

This paper focuses on the finite physical dimensions thermodynamics (FPDT)-based design of combined endoreversible power and refrigeration cycles (CCHP). Four operating schemes were analyzed, one for the summer season and three for the winter season. These basic CCHP cycles should define the reference ones, having the maximum possible energy and exergy efficiencies considering real restrictive conditions. The FPDT design is an entropic approach because it defines and uses the dependences between the reference entropy and the control operational parameters characterizing the external energy interactions of CCHP subsystems. The FPDT introduces a generalization of CCHP systems design, due to the particular influences of entropy variations of the working fluids substituted with influences of four operational finite dimensions control parameters, i.e., two mean log temperature differences between the working fluids and external heat sources and two dimensionless thermal conductance inventories. Two useful energy interactions, power and cooling rate, were used as operational restrictive conditions. It was assumed that there are consumers required for the supplied heating rates depending on the energy operating scheme. The FPDT modeling evaluates main thermodynamic and heat transfer performances. The FPDT model presented in this paper is a general one, applicable to all endoreversible trigeneration cycles.

scholarly journals Finite Physical Dimensions Thermodynamics Analysis and Design of Closed Irreversible Cycles

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3416
Author(s):  
Gheorghe Dumitrașcu ◽  
Michel Feidt ◽  
Ştefan Grigorean
Keyword(s):  
Thermal Conductance ◽  
Heat Output ◽  
Operational Parameters ◽  
Analysis And Design ◽  
The Mean ◽  
Internal Irreversibility ◽  
Heat Transfers ◽  
Operational Constraints ◽  
Log Temperatures ◽  
Physical Dimensions

This paper develops simplifying entropic models of irreversible closed cycles. The entropic models involve the irreversible connections between external and internal main operational parameters with finite physical dimensions. The external parameters are the mean temperatures of external heat reservoirs, the heat transfers thermal conductance, and the heat transfer mean log temperatures differences. The internal involved parameters are the reference entropy of the cycle and the internal irreversibility number. The cycle’s design might use four possible operational constraints in order to find out the reference entropy. The internal irreversibility number allows the evaluation of the reversible heat output function of the reversible heat input. Thus the cycle entropy balance equation to design the trigeneration cycles only through external operational parameters might be involved. In designing trigeneration systems, they must know the requirements of all consumers of the useful energies delivered by the trigeneration system. The conclusions emphasize the complexity in designing and/or optimizing the irreversible trigeneration systems.

scholarly journals Organic Rankine-Cycle Turbine Power Plant Utilizing Low Temperature Heat Sources

1980 ◽  
Author(s):  
V. Maizza
Keyword(s):  
Power Plant ◽  
Low Temperature ◽  
High Efficiency ◽  
Waste Heat ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Heat Sources ◽  
Operational Parameters ◽  
Working Fluids ◽  
Waste Energy

Utilizing and converting of existing low temperature and waste heat sources by the use of a high efficiency bottoming cycle is attractive and should be possible for many locations. This paper presents a theoretical study on possible combination of an organic Rankine-cycle turbine power plant with the heat pump supplied by waste energy sources. Energy requirements and system performances are analyzed using realistic design operating condition for a middle town. Some conversion systems employing working fluids other than water are being studied for the purpose of proposed application. Thermodynamic efficiencies, with respect to available resource, have been calculated by varying some system operating parameters at various reference temperature. With reference to proposed application equations and graphs are presented which interrelate the turbine operational parameters for some possible working fluids with computation results.

scholarly journals Energy and Exergy Efficiency Analysis of Fluid Flow and Heat Transfer in Sinter Vertical Cooler

Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4522
Author(s):  
Zude Cheng ◽  
Haitao Wang ◽  
Junsheng Feng ◽  
Yongfang Xia ◽  
Hui Dong
Keyword(s):  
Heat Transfer ◽  
Energy Efficiency ◽  
Fluid Flow ◽  
Waste Heat ◽  
Exergy Efficiency ◽  
Inlet Temperature ◽  
Operational Parameters ◽  
Flow And Heat Transfer ◽  
Maximum Value ◽  
Energy And Exergy

In order to fully understand the energy and exergy transfer processes in sinter vertical coolers, a simulation model of the fluid flow and heat transfer in a vertical cooler was established, and energy and exergy efficiency analyses of the gas–solid heat transfer in a vertical cooler were conducted in detail. Based on the calculation method of the whole working condition, the suitable operational parameters of the vertical cooler were obtained by setting the net exergy efficiency in the vertical cooler as the indicator function. The results show that both the quantity of sinter waste heat recovery (SWHR) and energy efficiency increased as the air flow rate (AFR) increased, and they decreased as the air inlet temperature (AIT) increased. The increase in the sinter inlet temperature (SIT) resulted in an increase in the quantity of SWHR and a decrease in energy efficiency. The air net exergy had the maximum value as the AFR increased, and it only increased monotonically as the SIT and AIT increased. The net exergy efficiency reached the maximum value as the AFR and AIT increased, and the increase in the SIT only resulted in a decrease in the net exergy efficiency. When the sinter annual production of a 360 m2 sintering machine was taken as the processing capacity of the vertical cooler, the suitable operational parameters of the vertical cooler were 190 kg/s for the AFR, and 353 K for the AIT.

Thermodynamic analysis of a wall mounted gas boiler with an organic Rankine cycle and hydrogen production unit

2017 ◽  
Vol 28 (7) ◽  
pp. 725-743 ◽  
Author(s):  
Anahita Moharamian ◽  
Saeed Soltani ◽  
Faramarz Ranjbar ◽  
Mortaza Yari ◽  
Marc A Rosen
Keyword(s):  
Hydrogen Production ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Inlet Pressure ◽  
Pinch Point ◽  
Working Fluids ◽  
Turbine Inlet ◽  
Energy And Exergy ◽  
Cogeneration System ◽  
Net Power Output

A novel cogeneration system based on a wall mounted gas boiler and an organic Rankine cycle with a hydrogen production unit is proposed and assessed based on energy and exergy analyses. The system is proposed in order to have cogenerational functionality and assessed for the first time. A theoretical research approach is used. The results indicate that the most appropriate organic working fluids for the organic Rankine cycle are HFE700 and isopentane. Utilizing these working fluids increases the energy efficiency of the integrated wall mounted gas boiler and organic Rankine cycle system by about 1% and the organic Rankine cycle net power output about 0.238 kW compared to when the systems are separate. Furthermore, increasing the turbine inlet pressure causes the net power output, the organic Rankine cycle energy and exergy efficiencies, and the cogeneration system exergy efficiency to rise. The organic Rankine cycle turbine inlet pressure has a negligible effect on the organic Rankine cycle mass flow rate. Increasing the pinch point temperature decreases the organic Rankine cycle turbine net output power. Finally, increasing the turbine inlet pressure causes the hydrogen production rate to increase; the highest and lowest hydrogen production rates are observed for the working fluids for HFE7000 and isobutane, respectively. Increasing the pinch point temperature decreases the hydrogen production rate. In the cogeneration system, the highest exergy destruction rate is exhibited by the wall mounted gas boiler, followed by the organic Rankine cycle evaporator, the organic Rankine cycle turbine, the organic Rankine cycle condenser, the proton exchange membrane electrolyzer, and the organic Rankine cycle pump, respectively.

Interactive Demonstration of an AC-130 Aircraft Virtual Reality Part Task Trainer

2017 ◽  
Vol 61 (1) ◽  
pp. 395-397
Author(s):  
Eric Sikorski ◽  
Amanda Palla
Keyword(s):  
Virtual Reality ◽  
High Speed ◽  
Development Program ◽  
Systems Design ◽  
Sensor Technology ◽  
Instructional Systems ◽  
Operational Parameters ◽  
Hand Motion ◽  
Head Mounted Display ◽  
Bare Hand

This session will demonstrate a Virtual Reality Part Task Trainer (vrPTT) that was developed under a Department of Defense funded research and development program. The vrPTT consists of Virtual Reality (VR) head mounted display (HMD) goggles and bare-hand motion sensor technology integrated via a high speed gaming computer that hosts an automated, intelligent tutor. Upon donning the VR goggles, the user is immersed into a cockpit of an AC-130 aircraft. The AC-130 system instruments are operationally accurate with selection and feedback indications true to aircraft operational parameters. The demonstration will allow participants to manipulate buttons and switches on a simulated checklist completion task within the immersive vrPTT environment. The Session attendees will gain an understanding of VR’s potential for DoD aircrew training from a human factors psychology and instructional systems design perspective by interacting with a developed capability.

scholarly journals How to compare energy performance requirements of Japanese and European office buildings

2019 ◽  
Vol 111 ◽  
pp. 03038
Author(s):  
Kaiser Ahmed ◽  
Gyuyoung Yoon ◽  
Makiko Ukai ◽  
Jarek Kurnitski
Keyword(s):  
Thermal Conductance ◽  
District Heating ◽  
Energy Performance ◽  
Office Building ◽  
Heat Sources ◽  
Building Model ◽  
Air Source Heat Pump ◽  
Performance Requirements ◽  
Insulation Thickness ◽  
Heating Degree Days

This study applied the normalisation method that enabled to compare the energy performance of buildings from European and Japanese climates. A reference office building was simulated with national input data and weather file in order to estimate the thermal conductance of building model and heating degree-days for a reference climate. Based on simulated results, economic insulation thickness and thermal transmittance of windows for all climates were determined. A reference office building corresponding to Japanese ZEB Ready performance was moved with this method to Estonian and French climates. The results compared to national NZEB requirements and EC NZEB Nordic and Oceanic recommendations. It was found that the Japanese ZEB Ready building configuration with air source heat pump was very close to EC NZEB recommendations. However, in the case of district heating and gas-boiler heat sources, it was needed to improve Japanese ZEB Ready building configuration in order to meet EC NZEB recommendations. Estonian NZEB requirement met EC recommendation with both heat sources, but French NZEB requirement was much less ambitious.

A new selection principle of working fluids for subcritical organic Rankine cycle coupling with different heat sources

Energy ◽  
2014 ◽  
Vol 68 ◽  
pp. 283-291 ◽  
Author(s):  
Chao He ◽  
Chao Liu ◽  
Mengtong Zhou ◽  
Hui Xie ◽  
Xiaoxiao Xu ◽  
...  
Keyword(s):  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Heat Sources ◽  
Working Fluids ◽  
Selection Principle

Optimization of Cycle and Expander Design of an Organic Rankine Cycle Unit Using Multi-Component Working Fluids

2016 ◽  
Author(s):  
Andrea Meroni ◽  
Jesper Graa Andreasen ◽  
Leonardo Pierobon ◽  
Fredrik Haglind
Keyword(s):  
Low Temperature ◽  
Power Systems ◽  
Waste Heat ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Fluid Temperature ◽  
Heat Sources ◽  
Working Fluids ◽  
Turbine Performance ◽  
Temperature Heat

Organic Rankine cycle (ORC) power systems represent attractive solutions for power conversion from low temperature heat sources, and the use of these power systems is gaining increasing attention in the marine industry. This paper proposes the combined optimal design of cycle and expander for an organic Rankine cycle unit utilizing waste heat from low temperature heat sources. The study addresses a case where the minimum temperature of the heat source is constrained and a case where no constraint is imposed. The former case is the waste heat recovery from jacket cooling water of a marine diesel engine onboard a large ship, and the latter is representative of a low-temperature geothermal, solar or waste heat recovery application. Multi-component working fluids are investigated, as they allow improving the match between the temperature profiles in the heat exchangers and, consequently, reducing the irreversibility in the ORC system. This work considers mixtures of R245fa/pentane and propane/isobutane. The use of multi-component working fluids typically results in increased heat transfer areas and different expander designs compared to pure fluids. In order to properly account for turbine performance and design constraints in the cycle calculation, the thermodynamic cycle and the turbine are optimized simultaneously in the molar composition range of each mixture. Such novel optimization approach enables one to identify to which extent the cycle or the turbine behaviour influences the selection of the optimal solution. It also enables one to find the composition for which an optimal compromise between cycle and turbine performance is achieved. The optimal ORC unit employs pure R245fa and provides approximately 200 kW when the minimum hot fluid temperature is constrained. Conversely, the mixture R245fa/pentane (0.5/0.5) is selected and provides approximately 444 kW when the hot fluid temperature is not constrained to a lower value. In both cases, a compact and efficient turbine can be manufactured.

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