Design and Performance Evaluation of a Trigeneration System Incorporating Hydraulic Storage and an Inverted Brayton Cycle

2008 ◽  
Vol 131 (1) ◽  
Author(s):  
Matthew Blieske ◽  
J. E. D. Gauthier ◽  
X. Huang
Keyword(s):  
High Efficiency ◽  
Small Scale ◽  
Brayton Cycle ◽  
Energy Prices ◽  
Air Conditioner ◽  
Single Family ◽  
Modes Of Operation ◽  
External Temperature ◽  
Generation Costs ◽  
The Individual

To bring the economic benefit of trigeneration to small-scale users without incorporating expensive components, an inverted Brayton cycle (IBC) is employed, which makes use of the expander section already present in a microturbine. An air accumulator provides pressurized air, which is passed through the expander section of the same microturbine used to charge the accumulator. The air passing through the IBC is cooled due to expansion, simultaneously providing power and cooling the flow. As the microturbine is indirectly fired, the flow passing through the engine or IBC can be directly vented into the household—eliminating the need for additional heat exchangers. The size of the cycle studied is on the order of 10 kW(e), suitable for a domestic household; however, the system is easily scaled for larger commercial applications. The majority of the components in the system being studied are “off the shelf” products. A feasibility study was conducted to ensure that the proposed system is economically competitive with systems currently used, such as individual generation provided by an air conditioner (A/C), a high efficiency natural gas (NG) furnace, and grid power. Simulations were run for a full year based on the actual external temperature and the electrical and thermal loads for a single family detached dwelling located in Winnipeg, Canada. Performance data were generated using MATLAB™ while the economic performance was determined with time-based simulations conducted using SIMULINK™. The system is designed to allow energy islanding by providing for all household energy needs throughout the year; however, integration with a power grid is optional. It was found that the operating costs for the proposed trigeneration system in an energy islanding mode of operation were equivalent to or less than individual generation (A/C unit, NG furnace, and grid power) during heating modes of operation and were more expensive for cooling modes of operation. The yearly energy cost for the trigeneration system exceeded the individual generation costs by 30–40%; however, there remains much room for improvement to the trigeneration concept. All economic data were based on fair market energy prices as found in central Canada.

Design and Performance Evaluation of a Trigeneration System Incorporating Hydraulic Storage and an Inverted Brayton Cycle

2008 ◽  
Author(s):  
Matthew Blieske ◽  
J. E. D. Gauthier ◽  
X. Huang
Keyword(s):  
High Efficiency ◽  
Small Scale ◽  
Brayton Cycle ◽  
Energy Prices ◽  
Air Conditioner ◽  
Single Family ◽  
Modes Of Operation ◽  
External Temperature ◽  
Generation Costs ◽  
The Individual

To bring the economic benefit of trigeneration to small-scale users without incorporating expensive components, an inverted Brayton cycle (IBC) is employed which makes use of the expander section already present in a microturbine. An air accumulator provides pressurized air, which is passed through the expander section of the same microturbine used to charge the accumulator. The air passing through the IBC is cooled due to expansion, simultaneously providing power and cooling flow. As the microturbine is indirectly fired, the flow passing through the engine or IBC can be directly vented into the household; eliminating the need for additional heat exchangers. The size of the cycle studied is on the order of 10 kW(e), suitable for a domestic household, however the system is easily scaled for larger commercial applications. The majority of the components in the system studied are ‘off the shelf’ products. A feasibility study was conducted to ensure the proposed system is economically competitive with systems currently used, such as individual generation provided by an air conditioner, high efficiency natural gas furnace, and grid power. Simulations were run for a full year based on actual external temperature, electrical, and thermal loads for a single family detached dwelling located in Winnipeg, Canada. Performance data was generated using Matlab™ while economic performance was determined with time-based simulations conducted using Simulink™. The system is designed to allow energy islanding by providing for all household energy needs throughout the year, however integration with a power grid is optional. It was found the operating costs for the proposed trigeneration system in an energy islanding mode of operation were marginally higher than individual generation (A/C unit, NG furnace, grid power) during heating modes of operation, and more expensive for cooling modes of operation. The yearly energy cost for the trigeneration system exceeded the individual generation costs by 30 to 40%, however there remains much room for improvement to the trigeneration concept. All economic data was based upon fair market energy prices as found in central Canada.

Structural Analysis of Small Scale Radial Turbine for Solar Powered Brayton Cycle Application

2018 ◽  
Author(s):  
Ahmed Mahmood Daabo ◽  
Saad Mahmoud ◽  
Raya K. Al-Dadah
Keyword(s):  
Rotational Speed ◽  
High Efficiency ◽  
Fluid Dynamic ◽  
Small Scale ◽  
Brayton Cycle ◽  
High Rotational Speed ◽  
Radial Turbine ◽  
Solar Powered ◽  
Maximum Increment ◽  
Cfd Optimization

Developing small scale turbines pauses challenges in terms of increased stresses due to high rotational speed leading to increase in component thicknesses and turbine overall weight. Therefore this study assesses both; the structural and aerodynamic performance of a Small Scale Radial Turbine SSRT by integrating finite-element methods FEM and Computational Fluid Dynamic CFD. Using Vista preliminary design model in ANSYS and detailed 3D CFD optimization, SSRT with 1–5 kW power for solar powered Brayton cycle was developed with high efficiency of 89.2%. Then both; the turbine’s hub and blades were structurally analysed under various loading conditions to investigate the effect of various rotational speeds and blade shapes on the stress distribution and deformation of the blades. The results of the current study showed that a maximum increment of 65% stress and 57% deformation was noticed when reaching the maximum studied rotational speed at inlet air temperature of 450 K.

Integrated Design and Multi-Objective Optimization of a Single Stage Heat-Pump Turbocompressor

2013 ◽  
Author(s):  
J. Schiffmann
Keyword(s):  
Design Optimization ◽  
High Efficiency ◽  
Integrated Design ◽  
Heat Pumps ◽  
Small Scale ◽  
Multi Objective Optimization ◽  
Design Constraints ◽  
Multi Objective ◽  
Wide Range ◽  
Standard Design

Small scale turbomachines in domestic heat pumps reach high efficiency and provide oil-free solutions which improve heat-exchanger performance and offer major advantages in the design of advanced thermodynamic cycles. An appropriate turbocompressor for domestic air based heat pumps requires the ability to operate on a wide range of inlet pressure, pressure ratios and mass flows, confronting the designer with the necessity to compromise between range and efficiency. Further the design of small-scale direct driven turbomachines is a complex and interdisciplinary task. Textbook design procedures propose to split such systems into subcomponents and to design and optimize each element individually. This common procedure, however, tends to neglect the interactions between the different components leading to suboptimal solutions. The authors propose an approach based on the integrated philosophy for designing and optimizing gas bearing supported, direct driven turbocompressors for applications with challenging requirements with regards to operation range and efficiency. Using previously validated reduced order models for the different components an integrated model of the compressor is implemented and the optimum system found via multi-objective optimization. It is shown that compared to standard design procedure the integrated approach yields an increase of the seasonal compressor efficiency of more than 12 points. Further a design optimization based sensitivity analysis allows to investigate the influence of design constraints determined prior to optimization such as impeller surface roughness, rotor material and impeller force. A relaxation of these constrains yields additional room for improvement. Reduced impeller force improves efficiency due to a smaller thrust bearing mainly, whereas a lighter rotor material improves rotordynamic performance. A hydraulically smoother impeller surface improves the overall efficiency considerably by reducing aerodynamic losses. A combination of the relaxation of the 3 design constraints yields an additional improvement of 6 points compared to the original optimization process. The integrated design and optimization procedure implemented in the case of a complex design problem thus clearly shows its advantages compared to traditional design methods by allowing a truly exhaustive search for optimum solutions throughout the complete design space. It can be used for both design optimization and for design analysis.

scholarly journals Design of Multi Standard Near Field Communication Outphasing Transmitter with Modulation Wave Shaping

Electronics ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 188
Author(s):  
Žiga Korošak ◽  
Nejc Suhadolnik ◽  
Anton Pleteršek
Keyword(s):  
Radio Frequency Identification ◽  
High Efficiency ◽  
Near Field ◽  
Cmos Technology ◽  
Near Field Communication ◽  
Differential Delay ◽  
Fully Differential ◽  
Delay Locked Loop ◽  
Modulation Wave ◽  
The Individual

The aim of this work is to tackle the problem of modulation wave shaping in the field of near field communication (NFC) radio frequency identification (RFID). For this purpose, a high-efficiency transmitter circuit was developed to comply with the strict requirements of the newest EMVCo and NFC Forum specifications for pulse shapes. The proposed circuit uses an outphasing modulator that is based on a digital-to-time converter (DTC). The DTC based outphasing modulator supports amplitude shift keying (ASK) modulation, operates at four times the 13.56 MHz carrier frequency and is made fully differential in order to remove the parasitic phase modulation components. The accompanying transmitter logic includes lookup tables with programmable modulation pulse wave shapes. The modulator solution uses a 64-cell tapped current controlled fully differential delay locked loop (DLL), which produces a 360° delay at 54.24 MHz, and a glitch-free multiplexor to select the individual taps. The outphased output from the modulator is mixed to create an RF pulse width modulated (PWM) output, which drives the antenna. Additionally, this implementation is fully compatible with D-class amplifiers enabling high efficiency. A test circuit of the proposed differential multi-standard reader’s transmitter was simulated in 40 nm CMOS technology. Stricter pulse shape requirements were easily satisfied, while achieving an output linearity of 0.2 bits and maximum power consumption under 7.5 mW.

scholarly journals Continuous-Flow Photocatalytic Microfluidic-Reactor for the Treatment of Aqueous Contaminants, Simplicity, and Complexity: A Mini-Review

Symmetry ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1325
Author(s):  
Zhongwei Gao ◽  
Changqing Pan ◽  
Chang-Ho Choi ◽  
Chih-Hung Chang
Keyword(s):  
Continuous Flow ◽  
Lower Energy ◽  
High Efficiency ◽  
Diffusion Length ◽  
Physical Adsorption ◽  
Chemical Oxidation ◽  
Microfluidic Reactor ◽  
Global Issue ◽  
The Individual ◽  
Aqueous Contaminants

Water pollution is a growing global issue; there are many approaches to treating wastewater, including chemical coagulation, physical adsorption, and chemical oxidation. The photocatalysis process has provided a solution for removing pollutants from wastewater, where the pair of the photoelectron and hole works through an asymmetric way to degrade the contaminants under UV irradiation. This method offers an alternative route for treating the pollutant with a lower energy cost, high efficiency, and fewer byproducts. A continuous-flow microfluidic reactor has a channel size from tens to thousands of micrometers, providing uniform irradiation and short diffusion length. It can enhance the conversion efficiency of photocatalysis due to the simple spatial symmetry inside the microreactor channel and among the individual channels. In addition, the bandgap of TiO2, ZnO, or other photocatalyst nanoparticles with symmetric crystal structure can be modified through doping or embedding. In this mini-review, a review of the reported continuous-flow photocatalytic microfluidic reactor is discussed from the perspective of both microreactor design and material engineering.

scholarly journals Profitability of Various Energy Supply Systems in Light of Their Different Energy Prices and Climate Conditions

Buildings ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 100 ◽  
Author(s):  
Elaheh Jalilzadehazhari ◽  
Georgios Pardalis ◽  
Amir Vadiee
Keyword(s):  
Renewable Energy ◽  
Heat Pump ◽  
Energy Supply ◽  
Ground Source Heat Pump ◽  
Energy Prices ◽  
Single Family ◽  
Climate Zones ◽  
Ground Source ◽  
Supply Systems ◽  
Energy Supply Systems

The majority of the single-family houses in Sweden are affected by deteriorations in building envelopes as well as heating, ventilation and air conditioning systems. These dwellings are, therefore, in need of extensive renovation, which provides an excellent opportunity to install renewable energy supply systems to reduce the total energy consumption. The high investment costs of the renewable energy supply systems were previously distinguished as the main barrier in the installation of these systems in Sweden. House-owners should, therefore, compare the profitability of the energy supply systems and select the one, which will allow them to reduce their operational costs. This study analyses the profitability of a ground source heat pump, photovoltaic solar panels and an integrated ground source heat pump with a photovoltaic system, as three energy supply systems for a single-family house in Sweden. The profitability of the supply systems was analysed by calculating the payback period (PBP) and internal rate of return (IRR) for these systems. Three different energy prices, three different interest rates, and two different lifespans were considered when calculating the IRR and PBP. In addition, the profitability of the supply systems was analysed for four Swedish climate zones. The analyses of results show that the ground source heat pump system was the most profitable energy supply system since it provided a short PBP and high IRR in all climate zones when compared with the other energy supply systems. Additionally, results show that increasing the energy price improved the profitability of the supply systems in all climate zones.

High Efficiency Energy Conversion System Based on Modified Brayton Cycle

2005 ◽  
Author(s):  
Anatoli A. Borissov ◽  
Alexander A. Borissov ◽  
Kenneth K. Kramer
Keyword(s):  
High Efficiency ◽  
Fuel Efficiency ◽  
Brayton Cycle ◽  
Positive Displacement ◽  
Heat Engines ◽  
Current State ◽  
Technological Advances ◽  
First Results ◽  
Power Generation Systems ◽  
Vortex Combustion

Each year, the users in the U.S. alone spend over $100 billion on various type of engines to produce power — electrical, mechanical, and thermal. Despite technological advances, most all of these power generation systems have only been fine tuned: the engine efficiencies may have been improved slightly, but the underlying thermodynamic principles have not been modified to effect a drastic improvement. The result is that most engines in service today suffer from two major problems: low fuel efficiency and emission of high levels of polluting gases in the exhaust gases. The current state of propulsion engines or distributed generation technologies using heat engines shows an average efficiency of between 20% and 40%. These low efficiencies in a high–cost energy market indicate a great need for more efficient technologies. This paper describes a new method of achieving a very high efficiency, namely optimizing every stage of the thermodynamic process-Brayton cycle. Two modified processes, such as isothermal compression and recuperation, add about 35% efficiency to the conventional Brayton cycle, making 60% efficiency for modified Brayton cycle. By utilizing a positive displacement compressor and expander with a novel vortex combustion chamber and a vortex recuperator, high levels of efficiency with low emissions and noise are possible. The prototype engine with low RPM and high torque has been built which use continuous combustion of different fuels under a constant pressure. First results of the engine’s components testing are presented.

scholarly journals Flexibility Reserve of Self-Consumption Optimized Energy Systems in the Household Sector

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3017
Author(s):  
Elias Dörre ◽  
Sebastian Pfaffel ◽  
Alexander Dreher ◽  
Pedro Girón ◽  
Svenja Heising ◽  
...  
Keyword(s):  
Unit Commitment ◽  
Programming Model ◽  
Weighted Average ◽  
Heat Pumps ◽  
Mixed Integer ◽  
Single Family ◽  
Unit Commitment Problem ◽  
Household Sector ◽  
The Future ◽  
The Individual

Energy generation and consumption in the power grid must be balanced at every single moment. Within the synchronous area of continental Europe, flexible generators and loads can provide Frequency Containment Reserve and Frequency Restoration Reserve marketed through the balancing markets. The Transmission System Operators use these flexibilities to maintain or restore the grid frequency when there are deviations. This paper shows the future flexibility potential of Germany’s household sector, in particular for single-family and twin homes in 2025 and 2030 with the assumption that households primarily optimize their self-consumption. The primary focus is directed to the flexibility potential of Electric Vehicles, Heat Pumps, Photovoltaics and Battery Storage Systems. A total of 10 different household system configurations were considered and combined in a weighted average based on the scenario framework of the German Grid Development Plan. The household generation, consumption and storage units were simulated in a mixed-integer linear programming model to create the time series for the self-consumption optimized households. This solved the unit commitment problem for each of the decentralized households in their individual configurations. Finally, the individual household flexibilities were evaluated and then aggregated to a Germany-wide flexibility profile for single-family and twin homes. The results indicate that the household sector can contribute significantly to system stabilization with an average potential of 30 negative and 3 positive flexibility in 2025. In 2030, the corresponding flexibilities potentially increase to 90 and 30 , respectively. This underlines that considerable flexibility reserves could be provided by single-family and twin homes in the future.

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