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.

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.

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.

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.

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.

Thermodynamic Assessment of Hybrid PSOFC/GT Systems for Mechanical/Electric Power Generation

2000 ◽  
Author(s):  
K. K. Botros ◽  
G. R. Price ◽  
R. Parker
Keyword(s):  
Power Generation ◽  
Electric Power ◽  
Gas Turbine ◽  
Life Cycle Cost ◽  
Pressure Ratio ◽  
Pollutant Emissions ◽  
Mechanical Power ◽  
Total Power ◽  
Specific Work ◽  
System Pressure

Hybrid PSOFC/GT cycles consisting of pressurized solid oxide fuel cells integrated into gas turbine cycles are emerging as a major new power generation concept. These hybrid cycles can potentially offer thermal efficiencies exceeding 70% along with significant reductions in greenhouse gas and NOX emissions. This paper considers the PSOFC/GT cycle in terms of electrical and mechanical power generation with particular focus on gas pipeline companies interested in diversifying their assets into distributed electric generation or lowering pollutant emissions while more efficiently transporting natural gas. By replacing the conventional GT combustion chamber with an internally reformed PSOFC, electrical power is generated as a by-product while hot gases exiting the fuel cell are diverted into the gas turbine for mechanical power. A simple one-dimensional thermodynamic model of a generic PSOFC/GT cycle has shown that overall thermal efficiencies of 65% are attainable, whilst almost tripling the specific work (i.e. energy per unit mass of air). The main finding of this paper is that the amount of electric power generated ranges from 60–80% of the total power available depending on factors such as the system pressure ratio and degree of supplementary firing before the gas turbine. Ultimately, the best cycle should be based on the “balance of plant”, which considers factors such as life cycle cost analysis, business and market focus, and environmental emission issues.

The Optimum Pressure Ratio for a Combined Cycle Gas Turbine Plant

1995 ◽  
Vol 209 (4) ◽  
pp. 259-264 ◽  
Author(s):  
J H Horlock
Keyword(s):  
Gas Turbine ◽  
Pressure Ratio ◽  
Combined Cycle ◽  
Maximum Efficiency ◽  
Specific Work ◽  
Optimum Pressure ◽  
Turbine Plant ◽  
Gas Turbine Plant ◽  
Overall Efficiency ◽  
Gas Turbine Cycle

A graphical method of calculating the performance of gas turbine cycles, developed by Hawthorne and Davis (1), is adapted to determine the pressure ratio of a combined cycle gas turbine (CCGT) plant which will give maximum overall efficiency. The results of this approximate analysis show that the optimum pressure ratio is less than that for maximum efficiency in the higher level (gas turbine) cycle but greater than that for maximum specific work in that cycle. Introduction of reheat into the higher cycle increases the pressure ratio required for maximum overall efficiency.

Thermodynamic Analysis a Novel Wave Rotor Refrigeration Cycle

2013 ◽  
Vol 805-806 ◽  
pp. 537-542 ◽  
Author(s):  
Jia Quan Zhao ◽  
Da Peng Hu ◽  
Pei Qi Liu ◽  
Feng Xia Liu ◽  
Jin Ji Gao
Keyword(s):  
Pressure Wave ◽  
Simple Structure ◽  
Pressure Ratio ◽  
Energy Transfer Efficiency ◽  
Refrigeration Cycle ◽  
Wave Rotor ◽  
Expansion Process ◽  
Compression Process ◽  
Compression Efficiency ◽  
Experimental Works

As a novel generation of thermal separators, the Wave rotor refrigerator (WRR) has replaced the traditional pressure-wave thermal separator. However, the isentropic refrigeration efficiency still needs to be improved compared with expander. A novel WRR system cycle was built and the system performance was thermal analyzed under various parameters, such as expansion efficiency or compression efficiency of wave rotor. The results are used to compare with the traditional WRR system. It is shown that the advantage provided by this novel cycle over the traditional WRR is an expansion process and a compression process is integrated into one unit, with a higher energy transfer efficiency and simple structure. The isentropic refrigeration efficiency of this novel cycle can be more than twice of the traditional WRR under the pressure ratio of 1.1. The experimental works are carrying out.

Comparing Water (R718) to Other Refrigerants

2006 ◽  
Author(s):  
Amir A. Kharazi ◽  
Norbert Mu¨ller
Keyword(s):  
High Pressure ◽  
Water Vapor ◽  
State Of The Art ◽  
Pressure Ratio ◽  
Cooling Capacity ◽  
Specific Work ◽  
High Pressure Ratio ◽  
Current State ◽  
Two Factors ◽  
Volumetric Cooling

Even though water (R718) is one of the oldest refrigerants, state of the art technology is required to use water as a refrigerant in compression refrigeration plants with turbo compressors. To compare water (R718) to other refrigerants, a code is developed in which all refrigerants can be compared in a single p-h, T-s, or p-T diagram. Using the code, the COP isolines of water (R718) and any refrigerant can be generated in a graph to determine which refrigerant has a better COP for a certain evaporation temperature and temperature lift. In regard to using water (R718) as a refrigerant, some specific features complicate its application in refrigeration plants with turbo compressors. Because the cycle works at very low pressure, the volumetric cooling capacity of water vapor is very low. Hence, huge volume flows have to be compressed with relatively high pressure ratios. Therefore, the use of water (R718) as a refrigerant, compared to classical refrigerants, such as R134a or R12, requires approximately 200 times the volume flow, and about twice the pressure ratio for the same applications. Because of the thermodynamic properties of water vapor, this high pressure ratio requires approximately a two to four times higher compressor tip speed, depending on the impeller design; while the speed of sound is approximately 2.5 times higher. Reynolds numbers are about 300 times lower and the specific work transmission per unit of mass has to be around 15 times higher. Two factors are introduced to compare the irreversibilities of R718 and other refrigerants and the main source of irrevercibility in R718 cycle is identified. Finally, the current state-of-the-art R718 is reviewed.

Parametric Analysis of Combined Gas-Steam Cycles

1987 ◽  
Vol 109 (1) ◽  
pp. 46-54 ◽  
Author(s):  
G. Cerri
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Parametric Analysis ◽  
State Of The Art ◽  
Pressure Ratio ◽  
The State ◽  
Point Of View ◽  
Compressed Air ◽  
Specific Work ◽  
Maximal Efficiency

Combined gas-steam cycles have been analyzed from the thermodynamic point of view. Suitable thermodynamics indices—explained in Appendix A—have been utilized. The parameters that most influence efficiency have been singled out and their ranges of variability have been specified. Calculations have been carried out—see Appendix B—taking into account the state of the art for gas turbines and the usual values for the quantities of steam cycles. The results are given. The maximal gas turbine temperature has been varied between 800°C and 1400°C. The gas turbine pressure ratio has been analyzed in the range of 2–24. Afterburning has also been taken into consideration. Maximal efficiency curves and the corresponding specific work curves (referred to the compressed air) related to the parameters of the analysis are given and discussed.

Parametric Analysis of Combined Gas-Steam Cycles

1982 ◽  
Author(s):  
G. Cerri
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Parametric Analysis ◽  
State Of The Art ◽  
Pressure Ratio ◽  
The State ◽  
Point Of View ◽  
Compressed Air ◽  
Specific Work ◽  
Maximal Efficiency

Combined gas-steam cycles have been analyzed from the thermodynamic point of view. Suitable thermodynamics indices — explained in Appendix A — have been utilized. The parameters that most influence efficiency have been singled out and their ranges of variability have been specified. Calculations have been carried out — see Appendix B — taking into account the state of the art for gas turbines and the usual values for the quantities of steam cycles. The results are given. The maximal gas turbine temperature has been varied between 800°C and 1400°C. The gas turbine pressure ratio has been analyzed in the range of 2–24. Afterburning has also been taken into consideration. Maximal efficiency curves and the corresponding specific work curves (referred to the compressed air) related to the parameters of the analysis are given and discussed.

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