Performance Benefits of R718 Turbo-Compression Cycle Using 3-Port Condensing Wave Rotors

2004 ◽  
Author(s):  
Amir A. Kharazi ◽  
Pezhman Akbari ◽  
Norbert Mu¨ller
Keyword(s):  
Performance Enhancement ◽  
The Novel ◽  
Wave Rotor ◽  
Flash Evaporation ◽  
Pressurized Water ◽  
Wave Rotors ◽  
Compression Cycle ◽  
Performance Map ◽  
Wave Compression ◽  
Novel Concept

A number of technical challenges have often hindered the economical application of refrigeration cycles using water (R718) as refrigerant. The novel concept of condensing wave rotor provides a solution for performance improvement of R718 refrigeration cycles. The wave rotor implementation can increase efficiency and reduce the size and cost of R718 units. The condensing wave rotor employs pressurized water to pressurize, desuperheat, and condense the refrigerant vapor — all in one dynamic process. In this study, the underlying phenomena of flash evaporation, shock wave compression, desuperheating, and condensation inside the wave rotor channels are described in a wave and phase-change diagram. A computer program based on a thermodynamic model is generated to evaluate the performance of R718 baseline and wave-rotor-enhanced cycles. The detailed thermodynamic approach for the baseline and the modified cycles is described. The effect of some key parameters on the performance enhancement is demonstrated as an aid for optimization. A generated performance map summarizes the findings.

Implementation of 3-Port Condensing Wave Rotors in R718 Cycles

2005 ◽  
Vol 128 (4) ◽  
pp. 325-334 ◽  
Author(s):  
Amir A. Kharazi ◽  
Pezhman Akbari ◽  
Norbert Müller
Keyword(s):  
Performance Improvement ◽  
Performance Enhancement ◽  
Pressure Ratio ◽  
Wave Rotor ◽  
Flash Evaporation ◽  
Pressurized Water ◽  
Wave Rotors ◽  
Performance Map ◽  
Wave Compression ◽  
Shock Wave Compression

The use of a novel 3-port condensing wave rotor is suggested to enhance the turbocompression in a refrigeration cycle that works only with water (R718) as a refrigerant. Although the implementation of such a wave rotor essentially reduces the size and cost of R718 units, their efficiency may also be increased. The condensing wave rotor employs pressurized water to pressurize, desuperheat, and condense the refrigerant vapor, all in one dynamic process. The underlying phenomena of flash evaporation, shock wave compression, desuperheating, and condensation inside the wave rotor channels are described in a wave and phase-change diagram. The thermodynamic process is shown in pressure-enthalpy and temperature-entropy diagrams. Based on the described thermodynamic model, a computer program was generated to evaluate the performance of R718 baseline and wave-rotor-enhanced cycles. The effect of some key parameters on the performance enhancement is demonstrated as an aid for optimization. A performance map summarizes the findings. It shows optimum wave rotor pressure ratio and maximum relative performance improvement of R718 cycles by using the 3-port condensing wave rotor.

Preliminary Study of a Novel R718 Turbo-Compression Cycle Using a 3-Port Condensing Wave Rotor

2004 ◽  
Author(s):  
Amir A. Kharazi ◽  
Pezhman Akbari ◽  
Norbert Mu¨ller
Keyword(s):  
Performance Enhancement ◽  
Pressure Ratio ◽  
Wave Rotor ◽  
Flash Evaporation ◽  
Pressurized Water ◽  
Compression Cycle ◽  
Performance Map ◽  
Wave Compression ◽  
Preliminary Study ◽  
Shock Wave Compression

Using a novel 3-port condensing wave rotor enhancing the turbo-compression in a R718 refrigeration cycle, which uses only water as a refrigerant, has been introduced. The wave-rotor implementation can increase efficiency and reduce size and cost of R718 units. The condensing wave rotor employs pressurized water to pressurize, desuperheat, and condense the refrigerant vapor — all in one dynamic process. The underlying phenomena of flash evaporation, shock wave compression, desuperheating, and condensation inside the wave rotor channels are described in a wave and phase-change diagram. The thermodynamic process is shown in pressure-enthalpy and temperature-entropy diagrams. A computer program based on a thermodynamic model was generated to evaluate the performance of R718 baseline and wave-rotor-enhanced cycles. The effect of some key parameters on the performance enhancement is demonstrated as an aid for optimization. A performance map summarizes the findings. It shows optimum wave rotor pressure ratio and maximum relative performance improvement of R718 cycles by using the 3-port condensing wave rotor.

Preliminary Study of a Novel R718 Compression Refrigeration Cycle Using a Three-Port Condensing Wave Rotor

2005 ◽  
Vol 127 (3) ◽  
pp. 539-544 ◽  
Author(s):  
Amir A. Kharazi ◽  
Pezhman Akbari ◽  
Norbert Mu¨ller
Keyword(s):  
Performance Enhancement ◽  
Pressure Ratio ◽  
Refrigeration Cycle ◽  
Wave Rotor ◽  
Flash Evaporation ◽  
Pressurized Water ◽  
Performance Map ◽  
Wave Compression ◽  
Preliminary Study ◽  
Shock Wave Compression

Using a novel 3-port condensing wave rotor enhancing the turbocompression in a R718 refrigeration cycle, which uses only water as a refrigerant, has been introduced. The wave-rotor implementation can increase efficiency and reduce size and cost of R718 units. The condensing wave rotor employs pressurized water to pressurize, desuperheat, and condense the refrigerant vapor—all in one dynamic process. The underlying phenomena of flash evaporation, shock wave compression, desuperheating, and condensation inside the wave rotor channels are described in a wave and phase-change diagram. The thermodynamic process is shown in pressure–enthalpy and temperature–entropy diagrams. A computer program based on a thermodynamic model was generated to evaluate the performance of R718 baseline and wave-rotor-enhanced cycles. The effect of some key parameters on the performance enhancement is demonstrated as an aid for optimization. A performance map summarizes the findings. It shows optimum wave rotor pressure ratio and maximum relative performance improvement of R718 cycles by using the 3-port condensing wave rotor.

scholarly journals A Review of Wave Rotor Technology and Its Applications

2004 ◽  
Author(s):  
Pezhman Akbari ◽  
Razi Nalim ◽  
Norbert Mu¨ller
Keyword(s):  
Gas Turbines ◽  
Experimental Studies ◽  
Operating Characteristics ◽  
Wave Rotor ◽  
Thermodynamic Cycles ◽  
The Past ◽  
Wave Rotors ◽  
Wide Range ◽  
Novel Concept ◽  
Analytical Approaches

The objective of this paper is to provide a succinct review of past and current research in developing wave rotor technology. This technology has shown unique capabilities to enhance the performance and operating characteristics of a variety of engines and machinery utilizing thermodynamic cycles. Although there have been numerous efforts in the past dealing with this novel concept, this technology is not yet widely used and barely known to engineers. Here, an attempt is made to summarize both the previously reported work in the literature and ongoing efforts around the world. The paper covers a wide range of wave rotor applications including the early attempts to use wave rotors, its successful commercialization as supercharges for car engines, research and development for gas turbine topping, and other developments. The review also pays close attention to more recent efforts: utilization of such devices in pressure-gain combustors, ultra-micro gas turbines, and water refrigeration systems, highlighting possible further efforts on this topic. Observations and lessons learnt from experimental studies, numerical simulations, analytical approaches, and other design and analysis tools are presented.

Performance Enhancement of One and Two-Shaft Industrial Turboshaft Engines Topped With Wave Rotors

2018 ◽  
Vol 35 (2) ◽  
pp. 137-147 ◽  
Author(s):  
Antonios Fatsis
Keyword(s):  
Gas Turbines ◽  
Performance Enhancement ◽  
Pressure Ratio ◽  
Inlet Temperature ◽  
Specific Work ◽  
Wave Rotor ◽  
Wave Rotors ◽  
Compressor Pressure Ratio ◽  
Industrial Gas Turbines ◽  
The One

Abstract Wave rotors are rotating equipment designed to exchange energy between high and low enthalpy fluids by means of unsteady pressure waves. In turbomachinery, they can be used as topping devices to gas turbines aiming to improve performance. The integration of a wave rotor into a ground power unit is far more attractive than into an aeronautical application, since it is not accompanied by any inconvenience concerning the over-weight and extra dimensioning. Two are the most common types of ground industrial gas turbines: The one-shaft and the two-shaft engines. Cycle analysis for both types of gas turbine engines topped with a four-port wave rotor is calculated and their performance is compared to the performance of the baseline engine accordingly. It is concluded that important benefits are obtained in terms of specific work and specific fuel consumption, especially compared to baseline engines with low compressor pressure ratio and low turbine inlet temperature.

scholarly journals Performance Enhancement of Microturbine Engines Topped With Wave Rotors

2004 ◽  
Vol 128 (1) ◽  
pp. 190-202 ◽  
Author(s):  
Pezhman Akbari ◽  
Razi Nalim ◽  
Norbert Müller
Keyword(s):  
Gas Turbines ◽  
Design Space ◽  
Performance Enhancement ◽  
Weather Conditions ◽  
Wave Rotor ◽  
Advantages And Disadvantages ◽  
Wave Rotors ◽  
Significant Performance ◽  
Hot Weather ◽  
The Impact

Significant performance enhancement of microturbines is predicted by implementing various wave-rotor-topping cycles. Five different advantageous cases are considered for implementation of a four-port wave rotor into two given baseline engines. In these thermodynamic analyses, the compressor and turbine pressure ratios and the turbine inlet temperatures are varied, according to the anticipated design objectives of the cases. Advantages and disadvantages are discussed. Comparison between the theoretic performance of wave-rotor-topped and baseline engines shows a performance enhancement up to 34%. General design maps are generated for the small gas turbines, showing the design space and optima for baseline and topped engines. Also, the impact of ambient temperature on the performance of both baseline and topped engines is investigated. It is shown that the wave-rotor-topped engines are less prone to performance degradation under hot-weather conditions than the baseline engines.

Utilizing Wave Rotor Technology to Enhance the Turbo Compression in Power and Refrigeration Cycles

2003 ◽  
Author(s):  
Pezhman Akbari ◽  
Amir A. Kharazi ◽  
Norbert Mu¨ller
Keyword(s):  
Power Generation ◽  
Dynamic Process ◽  
State Of The Art ◽  
Pressure Ratio ◽  
Refrigeration Cycle ◽  
Specific Work ◽  
Wave Rotor ◽  
Pressurized Water ◽  
Wave Rotors ◽  
Overall Efficiency

The objective of this paper is to review and suggest wave-rotor applications in power generation and refrigeration systems. The emphasis is on recent investigations performed by the authors for a microturbine (30 kW) and a novel enhancement of a state-of-the-art water (R718) compression refrigeration cycle. The results of thermodynamic analyses performed for the small gas turbine topped with a 4-port wave rotor show that engine overall efficiency and specific work may increase by up to about 33% without changing the compressor. Expecting similar advantages, it is suggested to use wave rotors in novel R718 compression refrigeration systems. This also introduces a new concept of a condensing wave-rotor that employs pressurized water to both (1) additional rise the pressure of the vapor and (2) desuperheat and condense it, all in one dynamic process. Adding the condensing wave-rotor to the refrigeration cycle allows for a lower pressure ratio of the compressor, which is crucial for the R718 chiller technology. Some structural and economic advantages of the proposed system are mentioned.

scholarly journals Racism and Antiracism in the Liberal International Order

2020 ◽  
pp. 1-24
Author(s):  
Zoltán I. Búzás
Keyword(s):  
International Relations ◽  
Racial Inequality ◽  
Racial Diversity ◽  
International Order ◽  
Interdisciplinary Studies ◽  
Racial Equality ◽  
The Novel ◽  
Current Regime ◽  
Novel Concept ◽  
Comprehensive Framework

Abstract Formal racial equality is a key aspect of the current Liberal International Order (LIO). It is subject to two main challenges: resurgent racial nationalism and substantive racial inequality. Combining work in International Relations with interdisciplinary studies on race, I submit that these challenges are the latest iteration of struggles between two transnational coalitions over the LIO's central racial provisions, which I call racial diversity regimes (RDRs). The traditional coalition has historically favored RDRs based on racial inequality and racial nationalism. The transformative coalition has favored RDRs based on racial equality and nonracial nationalism. I illustrate the argument by tracing the development of the liberal order's RDR as a function of intercoalitional struggles from one based on racial nationalism and inequality in 1919 to the current regime based on nonracial nationalism and limited equality. Today, racial nationalists belong to the traditional coalition and critics of racial inequality are part of the transformative coalition. The stakes of their struggles are high because they will determine whether we will live in a more racist or a more antiracist world. This article articulates a comprehensive framework that places race at the heart of the liberal order, offers the novel concept of “embedded racism” to capture how sovereignty shields domestic racism from foreign interference, and proposes an agenda for mainstream International Relations that takes race seriously.

scholarly journals Using green infrastructure to stimulate discourse with and for planning practice: experiences with fuzzy concepts from a pan-European, a national and a local perspective

2021 ◽  
Author(s):  
Rieke Hansen ◽  
Martina van Lierop ◽  
Werner Rolf ◽  
Damjana Gantar ◽  
Ina Šuklje Erjavec ◽  
...  
Keyword(s):  
Green Infrastructure ◽  
Regional Cooperation ◽  
Knowledge Exchange ◽  
Stakeholder Involvement ◽  
The Novel ◽  
Planning Practice ◽  
Regional Project ◽  
Development Processes ◽  
Guidance Documents ◽  
Novel Concept

AbstractConcepts such as green infrastructure, nature-based solutions, and ecosystem services gained popularity in recent discourses on urban planning. Despite their recognition as innovative concepts, all of them share a degree of ambiguity. Fuzziness can be a weakness but also an opportunity to shape novel concepts together with the stakeholders that are supposed to implement them in the planning practice. The paper traces concept development processes of green infrastructure through transdisciplinary knowledge exchange in three different projects, a European and a national research project and a local city-regional project as part of an EU regional cooperation project. In all projects, the green infrastructure concept evolved in different stages. Stakeholder involvement during these stages span from consultation to co-creation. The cases reveal two different approaches: concepts that are developed “for planning practice” might be based on a plethora of insight via consultation, while those “with planning practice” foster co-creation and might result in high acceptance among the involved stakeholders. Depending on the purpose of the novel concept, each approach can be beneficial and result in practice-related and operational products, such as guidance documents or planning strategies. However, the cases also show that in any new context an exchange about fuzzy concepts is not only needed but also a chance to stimulate cooperation and joint understanding about urban challenges and how to address them.

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