Scaling of Gas Turbine From Air to Refrigerants for Organic Rankine Cycle Using Similarity Concept

2015 ◽  
Vol 138 (6) ◽  
Author(s):  
Choon Seng Wong ◽  
Susan Krumdieck
Keyword(s):  
Gas Turbine ◽  
Test Bench ◽  
Pressure Ratio ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Expansion Ratio ◽  
Performance Estimation ◽  
Working Fluids ◽  
Turbine Performance ◽  
Performance Map

Similitude, or similarity concept, is an essential concept in turbomachinery to allow the designer to scale a turbine design to different sizes or different working fluids without repeating the whole design and development process. Similarity concept allows the testing of a turbomachine in a simple air test bench instead of a full-scale organic Rankine cycle (ORC) test bench. The concept can be further applied to adapt an existing gas turbine as an ORC turbine using different working fluids. This paper aims to scale an industrial gas turbine to different working fluids, other than the fluid the turbine was originally designed for. The turbine performance map for air was generated using the 3D computational fluid dynamics (CFD) analysis tools. Three different approaches using the similarity concept were applied to scale the turbine performance map using air and generate the performance map for two refrigerants: R134a and R245fa. The scaled performance curves derived from the air performance data were compared to the performance map generated using CFD analysis tools for R134a and R245fa. The three approaches were compared in terms of the accuracy of the performance estimation, and the most feasible approach was selected. The result shows that complete similarity cannot be achieved for the same turbomachine with two different working fluids, even at the best efficiency point for particular expansion ratio. If the constant pressure ratio is imposed, the location of the optimal velocity ratio and optimal specific speed would be underestimated with calculation error over 20%. Constant Δh0s/a012 was found to provide the highest accuracy in the performance estimation, but the expansion ratio (or pressure ratio) is varying using different working fluids due to the variation of sound speed. The differences in the fluid properties and the expansion ratio lead to the deviation in turbine performance parameters, velocity diagram, turbine's exit swirl angle, and entropy generation. The use of Δh0s/a012 further limits the application of the gas turbine for refrigerants with heavier molecular weight to a pressure ratio less than the designed pressure ratio using air. The specific speed at the best efficiency point was shifted to a higher value if higher expansion ratio was imposed. A correction chart for R245fa was attempted to estimate the turbine's performance at higher expansion ratio as a function of volumetric flow ratio.

scholarly journals Comparative investigation of working fluids for an organic Rankine cycle with geothermal water

2015 ◽  
Vol 36 (2) ◽  
pp. 75-84
Author(s):  
Yan-Na Liu ◽  
Song Xiao
Keyword(s):  
Power Generation ◽  
Pressure Ratio ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Comparative Investigation ◽  
Geothermal Water ◽  
Thermodynamic Investigation ◽  
Working Fluids ◽  
Temperature Heat ◽  
Input Pressure

AbstractIn this paper, the thermodynamic investigation on the use of geothermal water (130 °C as maximum) for power generation through a basic Rankine has been presented together with obtained main results. Six typical organic working fluids (i.e., R245fa, R141b, R290, R600, R152a, and 134a) were studied with modifying the input pressure and temperature to the turbine. The results show that there are no significant changes taking place in the efficiency for these working fluids with overheating the inlet fluid to the turbine, i.e., efficiency is a weak function of temperature. However, with the increasing of pressure ratio in the turbine, the efficiency rises more sharply. The technical viability is shown of implementing this type of process for recovering low temperature heat resource.

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.

scholarly journals Numerical Study of Multistage Transcritical Organic Rankine Cycle Axial Turbines

2014 ◽  
Vol 136 (8) ◽  
Author(s):  
L. Sciacovelli ◽  
P. Cinnella
Keyword(s):  
Numerical Study ◽  
Pressure Ratio ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Operating Conditions ◽  
Working Fluid ◽  
Dense Gas ◽  
Working Fluids ◽  
Inlet Conditions ◽  
The Impact

Transonic flows through axial, multistage, transcritical organic rankine cycle (ORC) turbines are investigated by using a numerical solver including advanced multiparameter equations of state and a high-order discretization scheme. The working fluids in use are the refrigerants R134a and R245fa, classified as dense gases due to their complex molecules and relatively high molecular weight. Both inviscid and viscous numerical simulations are carried out to quantify the impact of dense gas effects and viscous effects on turbine performance. Both supercritical and subcritical inlet conditions are studied for the considered working fluids. In the former case, flow across the turbine is transcritical, since turbine output pressure is subcritical. Numerical results show that, due to dense gas effects characterizing the flow at supercritical inlet conditions, supercritical ORC turbines enable, for a given pressure ratio, a higher isentropic efficiency than subcritical turbines using the same working fluid. Moreover, for the selected operating conditions, R134a provides a better performance than R245fa.

scholarly journals Performance analysis of organic Rankine cycle power generation system for intercooled cycle gas turbine

2018 ◽  
Vol 10 (8) ◽  
pp. 168781401879407 ◽  
Author(s):  
Wei Liu ◽  
Xiaoyun Zhang ◽  
Ningbo Zhao ◽  
Chunying Shu ◽  
Shanke Zhang ◽  
...  
Keyword(s):  
Power Generation ◽  
Gas Turbine ◽  
Output Power ◽  
Waste Heat ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Operating Conditions ◽  
Generation System ◽  
Working Fluids ◽  
Power Generation System

Intercooled cycle gas turbine has great potential in improving the output power because of the low energy consumption of high-pressure compressor. In order to more efficiently recovery and utilize the waste heat of the intercooled system, an organic Rankine cycle power generation system is developed to replace the traditional intercooled system in this study. Considering the effects of different kinds of organic working fluids, the thermodynamic performance of organic Rankine cycle power generation system is investigated in detail. On this basis, the sensitivity analyses of some key parameters are conducted to study the operating improvements of organic Rankine cycle power generation system. The results indicate that the integration of organic Rankine cycle and intercooled cycle gas turbine not only can be used for waste heat power generation but also increases the output power and efficiency of intercooled cycle gas turbine by selecting the organic working fluids of n-butane (R600), n-pentane (R601), toluene, and n-heptane. And compared to the others, organic Rankine cycle power generation system with toluene exhibits the best performance. The maximum enhancements of output power and thermal efficiency are 6.08% and 2.14%, respectively. Moreover, it is also concluded that both ambient temperatures and intercooled cycle gas turbine operating conditions are very important factors affecting the operating performances of organic Rankine cycle power generation system.

Organic Rankine Cycle Optimization With Explicit Designs of Evaporator and Radial Inflow Turbine

2020 ◽  
Vol 142 (7) ◽  
Author(s):  
Hasan Eren Bekiloğlu ◽  
Hasan Bedir ◽  
Günay Anlaş
Keyword(s):  
Power Output ◽  
Pressure Ratio ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Working Fluid ◽  
Working Fluids ◽  
Source Temperature ◽  
Order Preference ◽  
Radial Inflow Turbine ◽  
Net Power Output

Abstract Although there are studies on optimizing organic Rankine cycles (ORCs) through individual components, in this study, for the first time, both evaporator and turbine designs are included in a multiobjective optimization. Twenty-eight working fluids are used to find optimum cycle parameters for three source temperatures (90, 120, and 150 °C). A mean-line radial inflow turbine model is used. Nondominated Sorting Genetic Algorithm II is utilized to minimize total evaporator area per net power output and maximize performance factor simultaneously. The technique for Order Preference by Similarity to Ideal Situation (TOPSIS) procedure is followed to obtain ideal solutions. A group of working fluids with highest net power output is determined for each heat source temperature. Optimized geometric parameters of the evaporator vary in a narrow range independent of the working fluid and the source temperature, but evaporator PPTD and degree of superheating depend on the working fluid. The specific speed, the pressure ratio through the turbine, and the nozzle inlet-to-outlet radius ratio do not change significantly with cycle conditions.

Experimental Investigation of a Non-Ideal Expansion Flow of Siloxane Vapor MDM

2016 ◽  
Author(s):  
Andrea Spinelli ◽  
Fabio Cozzi ◽  
Vincenzo Dossena ◽  
Paolo Gaetani ◽  
Marta Zocca ◽  
...  
Keyword(s):  
Total Pressure ◽  
Compressible Flows ◽  
Pressure Ratio ◽  
Organic Rankine Cycle ◽  
Compressibility Factor ◽  
Rankine Cycle ◽  
Expansion Ratio ◽  
Settling Chamber ◽  
Blow Down ◽  
Organic Vapors

Nozzle flows of siloxane fluid MDM (C8H24O2Si3, octamethyltrisiloxane) expanding to supersonic speeds in non-ideal conditions are observed experimentally for the first time in the Test-Rig for Organic Vapors (TROVA) at Politencnico di Milano. The TROVA is a blow-down facility for investigating non-ideal compressible flows of organic vapors typical of Organic Rankine Cycle (ORC) applications. Total conditions in the settling chamber are subcritical and superheated, with total presssure 3.15 bar and total temperature 246 °C. In these conditions, the thermodynamic model predicts a value of the compressibility factor and of the fundamental derivative of gasdynamics equal to Z = 0.884 < 1 and Γ = 0.885 < 1, respectively. The total pressure and temperature are monitored during the test runs, together with the static pressure at selected stations along the nozzle axis. A double-passage Schlieren is used to visualize the density gradients within the nozzle. The nozzle is a convergent-divergent planar nozzle with a throat area of 16.8 mm (height) × 18.7 mm (width). Differently from dilute gas conditions, for a constant total-to-ambient expansion ratio, the static-to-total pressure ratio measured at the geometrical throat is observed to slightly depend on the reservoir conditions.

scholarly journals The Method of the Working Fluid Selection for Organic Rankine Cycle (ORC) Systems Employing Volumetric Expanders

Energies ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 573 ◽  
Author(s):  
Piotr Kolasiński
Keyword(s):  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Expansion Ratio ◽  
Thermal Capacity ◽  
Working Fluid ◽  
Working Fluids ◽  
Mean Temperature ◽  
Working Medium ◽  
Working Fluid Selection ◽  
Selection Of

The working fluid selection is one of the most important issues faced when designing Organic Rankine Cycle (ORC) systems. The choice of working fluid is dictated by different criteria. The most important of them are safety of use, impact on the environment, and physical and chemical parameters. The type of ORC system in which the working fluid is to be used and the type of expander applied in this system is also affecting the working fluid selection. Nowadays, volumetric expanders are increasingly used in ORC systems. In the case of volumetric expanders, in addition to the aforementioned working fluid selection criteria, additional parameters are considered during the selecting of the working fluid, such as the range of operating pressures and geometric dimensions (determining the volume of working chambers) affecting the achieved power and efficiency of the expander. This article presents a method of selecting a working medium for ORC systems using volumetric expanders. This method is based on the dimensionless rating parameters applied for the comparative analysis of different working fluids. Dimensionless parameters were defined for selected thermal properties of the working fluids, namely thermal capacity, mean temperature of evaporation, mean temperature of condensation, pressure and volumetric expansion ratio, volumetric expandability, as well as the heat of preheating, vaporization, superheating, cooling, and liquefaction. Moreover, isentropic expansion work was considered as the rating parameter. In this article, in addition to the working fluid selection method, computational examples related to the selection of the working fluid for the ORC system fed by a heat source featuring specified temperatures are presented. The results of calculations of rating parameters and their comparison gave an outlook on the selection of appropriate working fluids.

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