Analysis of Off-Design Behavior of a Solar-Fossil Hybrid Combined Cycle Plant Using a Small Particle Heat Exchange Receiver (SPHER) With a Variable Guide Vane Gas Turbine

2016 ◽  
Author(s):  
Matthew Miguel Virgen ◽  
Fletcher Miller
Keyword(s):  
Heat Exchange ◽  
Gas Turbine ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Small Particle ◽  
Guide Vane ◽  
Rankine Cycle ◽  
Combined Cycle ◽  
Inlet Temperature

Two significant goals in solar plant operation are lower cost and higher efficiencies. This is both for general competitiveness of solar technology in the energy industry, and also to meet the US DOE Sunshot Initiative Concentrating Solar Power (CSP) cost goals [1]. We present here an investigation on the effects of adding a bottoming steam power cycle to a solar-fossil hybrid CSP plant based on a Small Particle Heat Exchange Receiver (SPHER) driving a gas turbine as the primary cycle. Due to the high operating temperature of the SPHER being considered (over 1000 Celsius), the exhaust air from the primary Brayton cycle still contains a tremendous amount of exergy. This exergy of the gas flow can be captured in a heat recovery steam generator (HRSG), to generate superheated steam and run a bottoming Rankine cycle, in a combined cycle gas turbine (CCGT) system. A wide range of cases were run to explore options for maximizing both power and efficiency from the proposed CSP CCGT plant. Due to the generalized nature of the bottoming cycle modeling, and the varying nature of solar power, special consideration had to be given to the behavior of the heat exchanger and Rankine cycle in off-design scenarios. Variable guide vanes (VGVs), which can control the mass flow rate through the gas turbine system, have been found to be an effective tool in providing operational flexibility to address the variable nature of solar input. The effect VGVs and the operating range associated with them are presented. Strategies for meeting a minimum solar share are also explored. Trends with respect to the change in variable guide vane angle are discussed, as well as the response of the HRSG and bottoming Rankine cycle in response to changes in the gas mass flow rate and temperature. System efficiencies in the range of 50% were found to result from this plant configuration. However, a combustor inlet temperature (CIT) limit lower than a turbine inlet temperature (TIT) limit leads two distinct Modes of operation, with a sharp drop in both plant efficiency and power occurring when the air flow through the receiver exceeded the (CIT) limit, and as a result would have to bypass the combustor entirely and enter the turbine at a significantly lower temperature than nominal. Until that limit is completely eliminated through material or design improvements, this drawback can be addressed through strategic use of the variable guide vanes. Optimal operational strategy is ultimately decided by economics, plant objectives, or other market incentives.

scholarly journals Off-Design Performances of an Organic Rankine Cycle for Waste Heat Recovery from Gas Turbines

Energies ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1105 ◽  
Author(s):  
Carlo Carcasci ◽  
Lapo Cheli ◽  
Pietro Lubello ◽  
Lorenzo Winchler
Keyword(s):  
Gas Turbine ◽  
Mass Flow Rate ◽  
Air Temperature ◽  
Mass Flow ◽  
Flow Rate ◽  
Power Output ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Ambient Air ◽  
Air Mass

This paper presents an off-design analysis of a gas turbine Organic Rankine Cycle (ORC) combined cycle. Combustion turbine performances are significantly affected by fluctuations in ambient conditions, leading to relevant variations in the exhaust gases’ mass flow rate and temperature. The effects of the variation of ambient air temperature have been considered in the simulation of the topper cycle and of the condenser in the bottomer one. Analyses have been performed for different working fluids (toluene, benzene and cyclopentane) and control systems have been introduced on critical parameters, such as oil temperature and air mass flow rate at the condenser fan. Results have highlighted similar power outputs for cycles based on benzene and toluene, while differences as high as 34% have been found for cyclopentane. The power output trend with ambient temperature has been found to be influenced by slope discontinuities in gas turbine exhaust mass flow rate and temperature and by the upper limit imposed on the air mass flow rate at the condenser as well, suggesting the importance of a correct sizing of the component in the design phase. Overall, benzene-based cycle power output has been found to vary between 4518 kW and 3346 kW in the ambient air temperature range considered.

Design and Analysis of the Axial Bypass Compressor Blade of the Supercritical CO2 Gas Turbine

2009 ◽  
Author(s):  
Takao Ishizuka ◽  
Yasushi Muto ◽  
Masanori Aritomi ◽  
Nobuyoshi Tsuzuki ◽  
Hiroshige Kikura
Keyword(s):  
Gas Turbine ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Thermal Efficiency ◽  
Inlet Pressure ◽  
Inlet Temperature ◽  
Pressure Side ◽  
Aerodynamic Design ◽  
Co2 Gas

A supercritical carbon dioxide (S-CO2) gas turbine can generate power at a high cycle thermal efficiency, even at a modest temperature level of 500–550°C. Its high thermal efficiency is attributed to markedly reduced compressor work at the vicinity of the critical point. Furthermore, the reaction between Na and CO2 is milder than that between H2O and Na. Consequently, a more reliable and economically advantageous power generation system is achieved by coupling with a Na cooled fast reactor. In a typical design, the reactor thermal power, a turbine inlet pressure and an inlet temperature are, respectively, 600 MW, 20 MPa and 527°C. In the S-CO2 gas turbine system, a partial cooling cycle is used to compensate a difference in heat capacity for the high-temperature – low-pressure side and the low-temperature – high-pressure side of the recuperators to achieve high cycle thermal efficiency. The flow is divided into two streams before the precooler. One stream goes to recuperator 2 via a main compressor (MC); the other goes to recuperator 1 via a bypass compressor (BC). The performance and integrity of these two compressors are crucial. As described herein, an aerodynamic design of BC is given. The inlet temperature, inlet pressure, exit pressure and mass flow rate are, respectively, 77°C, 8 MPa, 20 MPa and 1392 kg/s. The salient features of this compressor are its compact size and a large bending stress caused by the large mass flow rate. The number of stages is numerous associated with the large enthalpy rise compared with MC. To achieve as high efficiency as possible, not a centrifugal type but an axial type is examined first. The aerodynamic design was conducted using one-dimensional design method, where the loss model of Cohen et al. is used. Its aerodynamic design enables the use of several stages and provides total adiabatic efficiency of 21 and 87%, respectively. Then, CFD analysis was conducted using “FLUENT”. Blade shapes were prepared based on flow angles and chord length obtained in the aerodynamic design. The CO2 properties in a fluid computer dataset “PROPATH” were used. The features of gas velocity distribution and pressure distribution were confirmed to the fundamental knowledge. The value of the calculated flow rate coincided very well with that of the design.

Experimental Investigation of a Pilot Compression Chiller With Alternatives Refrigerants R401a and R134a

2005 ◽  
Author(s):  
M. Fatouh
Keyword(s):  
Experimental Investigation ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Water Mass ◽  
Cooling Water ◽  
Cooling Capacity ◽  
Inlet Temperature ◽  
Chilled Water ◽  
Water Mass Flow Rate

This paper reports the results of an experimental investigation on a pilot compression chiller (4 kW cooling capacity) working with R401a and R134a as R12 alternatives. Experiments are conducted on a single-stage vapor compression refrigeration system using water as a secondary working fluid through both evaporator and condenser. Influences of cooling water mass flow rate (170–1900 kg/h), cooling water inlet temperature (27–43°C) and chilled water mass flow rate (240–1150 kg/h) on performance characteristics of chillers are evaluated for R401a, R134a and R12. Increasing cooling water mass flow rate or decreasing its inlet temperature causes the operating pressures and electric input power to reduce while the cooling capacity and coefficient of performance (COP) to increase. Pressure ratio is inversely proportional while actual loads and COP are directly proportional to chilled water mass flow rate. The effect of cooling water inlet temperature, on the system performance, is more significant than the effects of cooling and chilled water mass flow rates. Comparison between R12, R134a and R401a under identical operating conditions revealed that R401a can be used as a drop-in refrigerant to replace R12 in water-cooled chillers.

scholarly journals Analytical and Experimental Investigation of a Plate Fin Heat Exchanger at Cryogenics Temperature

2021 ◽  
Vol 39 (4) ◽  
pp. 1225-1235
Author(s):  
Ajay K. Gupta ◽  
Manoj Kumar ◽  
Ranjit K. Sahoo ◽  
Sunil K. Sarangi
Keyword(s):  
Heat Exchanger ◽  
Pressure Drop ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Heat Exchangers ◽  
Cryogenic Temperature ◽  
Operating Conditions ◽  
Inlet Temperature ◽  
Compact Size

Plate-fin heat exchangers provide a broad range of applications in many cryogenic industries for liquefaction and separation of gasses because of their excellent technical advantages such as high effectiveness, compact size, etc. Correlations are available for the design of a plate-fin heat exchanger, but experimental investigations are few at cryogenic temperature. In the present study, a cryogenic heat exchanger test setup has been designed and fabricated to investigate the performance of plate-fin heat exchanger at cryogenic temperature. Major parameters (Colburn factor, Friction factor, etc.) that affect the performance of plate-fin heat exchangers are provided concisely. The effect of mass flow rate and inlet temperature on the effectiveness and pressure drop of the heat exchanger are investigated. It is observed that with an increase in mass flow rate effectiveness and pressure drop increases. The present setup emphasis the systematic procedure to perform the experiment based on cryogenic operating conditions and represent its uncertainties level.

Experimental Study on the Performance of a See-Through Labyrinth Seal With Two-Phase, Mainly-Liquid Mixtures

2020 ◽  
Author(s):  
Min Zhang ◽  
Dara W. Childs
Keyword(s):  
Experimental Study ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Labyrinth Seal ◽  
Test Fluid ◽  
Inlet Temperature ◽  
Pure Liquid ◽  
Pump Rotor ◽  
Piston Seal

Abstract With the increasing demand of the oil & gas industry, many pump companies are developing multiphase pumps, which can handle liquid-gas flow directly without separating the liquid from a mixed flow. The see-through labyrinth seal is one of the popular types of non-contact annular seals that act as a balancing piston seal to reduce the axial thrust of a high-performance centrifugal pump. The see-through labyrinth seal also generates reaction forces that can significantly impact the rotordynamic performance of the pump. Multiphase pumps are expected to operate from pure-liquid to pure-gas conditions. Zhang et al. (2019) conducted a comprehensive experimental study on the performance (leakage and rotordynamic coefficients) of a see-through labyrinth seal under mainly-gas conditions. This paper continues Zhang et al.’s (2019) research and studies the performance of the see-through TOS (tooth-on-stator) labyrinth seal under mainly-liquid conditions. The test seal’s inner diameter, length, and radial clearance are 89.256 mm, 66.68 mm, and 0.178 mm, respectively. The test fluid is a mixture of air and silicone oil (PSF-5cSt), and the inlet GVF (gas volume fraction) varies from zero to 12%. Tests are conducted at an exit pressure of 6.9 bars, an inlet temperature of 39.1 °C, three pressure drops PDs (27.6 bars, 34.5 bars, and 48.3 bars), and three rotating speeds ω (5 krpm, 10 krpm, and 15 krpm). The seal is always concentric with the rotor, and there is no intentional fluid pre-rotation at the seal inlet. The air presence in the oil flow significantly impacts the leakage as well as the dynamic forces of the test seal. The first air increment (increasing inlet GVF from 0% to 3%) slightly increases the leakage mass flow rate, while further air increments steadily decrease the leakage mass flow rate. For all test conditions, the leakage mass flow rate does not change as ω increases from 5 krpm to 10 krpm but decreases as ω is further increased to 15 krpm. The reduction in the leakage mass flow rate indicates that there is an increase in the friction factor, and there could be a highly possible flow regime change as ω increases from 10 krpm to 15 krpm. For ω ≤ 10 krpm, effective stiffness Keff increases as inlet GVF increases. Keff represents the test seal’s total centering force on the pump rotor. The increase of Keff increases the seal’s centering force and would increase the pump rotor’s critical speeds. Ceff indicates the test seal’s total damping force on the pump rotor. For ω ≤ 10 krpm, Ceff first decreases as inlet GVF increases from zero to 3%, and then remains unchanged as inlet GVF is further increased to 12%. For ω = 15 krpm, Keff first increases as inlet GVF increases from zero to 3% and then decreases as inlet GVF is further increased. As inlet GVF increases, Ceff steadily decreases for ω = 15 krpm.

Cylindrical Parabolic Trough Concentrator and Solar Tower Comparison in an Integrated Solar Combined Cycle Power Plant

2019 ◽  
Author(s):  
Héctor J. Bravo ◽  
José C. Ramos ◽  
César Celis
Keyword(s):  
Power Plant ◽  
Ambient Temperature ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Combined Cycle ◽  
Parabolic Trough ◽  
Combined Cycle Power Plant ◽  
Design Point ◽  
Concentrated Solar Energy

Abstract The intermittency of renewable energies continues to be a limitation for their more widespread application because their large-scale storage is not yet practical. Concentrating solar power (CSP) has the possibility of thermally storing this energy to be used in times of higher demand at a more feasible storage price. The number of concentrated solar energy related projects have grown rapidly in recent years due to the advances in the associated solar technology. Some of the remaining issues regarding the associated high investment costs can be solved by integrating the solar potential into fossil fuel generation plants. An integrated solar combined cycle system (ISCCS) tends to be less dependent to climatic conditions and needs less capital inversion than a CSP system, letting the plant be more reliable and more economically feasible. In this work thus, two technologies of solar concentration (i) parabolic trough cylinder (PTC) and (ii) solar tower (ST) are initially integrated into a three-pressure levels combined cycle power plant. The proposed models are then modeled, simulated and properly assessed. Design and off design point computations are carried out taking into account local environmental conditions such as ambient temperature and direct solar radiation (DNI). The 8760 hourly-basis simulations carried out allow comparing the thermal and economic performance of the different power plant configurations accounted for in this work. The results show that injecting energy into the cycle at high temperatures does not necessarily imply a high power plant performance. In the studied plant configurations, introducing the solar generated steam mass flow rate at the evaporator outlet is slightly more efficient than introducing it at cycle points where temperatures are higher. At design point conditions thus, the plant configuration where the referred steam mass flow rate is introduced at the evaporator outlet generates 0.42% more power than those in which the steam is injected at higher cycle temperatures. At off design point conditions this value is reduced to 0.37%. The results also show that the months with high DNI values and those with low mean ambient temperatures are not necessarily the months which lead to the highest power outputs. In fact a balance between these two parameters, DNI and ambient temperature, leads to an operating condition where the power output is the highest. All plant configurations analyzed here are economically feasible, even so PTC related technologies tend to be more economically feasible than ST ones due to their lower investment costs.

Effect of Mass Flow Rate on Dryer Room Radiator Pressure Drop and Heat Transfer

2016 ◽  
Vol 836 ◽  
pp. 102-108
Author(s):  
Mirmanto ◽  
Emmy Dyah Sulistyowati ◽  
I Ketut Okariawan
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Electrical Power ◽  
Maximum Temperature ◽  
Inlet Temperature ◽  
Mass Flow Rates ◽  
Room Model

In the rainy season, in tropical countries, to dry stuffs is difficult. Using electrical power or fossil energy is an expensive way. Therefore, it is wise to utilize heat waste. A device that can be used for this purpose is called radiator. The effect of mass flow rate on pressure drop and heat transfer for a dryer room radiator have been experimentally investigated. The room model size was 1000 mm x 1000 mm x 1000 mm made of plywood and the overall radiator dimension was 360 mm x 220 mm x 50 mm made of copper pipes with aluminium fins. Three mass flow rates were investigated namely 12.5 g/s, 14 g/s and 16.5 g/s. The water temperature at the entrance was increased gradually and then kept at 80°C. The maximum temperature reached in the dryer room was 50°C which was at the point just above the radiator. The effect of the mass flow rate on the room temperature was insignificant, while the effect on the pressure drop was significant. Moreover, the pressure drop decreased as the inlet temperature increased. In general, the radiator is recommended to be used as the heat source in a dryer room.

Three-Dimensional Fluid Dynamics and Radiative Heat Transfer Modeling of a Small Particle Solar Receiver

2013 ◽  
Author(s):  
Pablo Fernández del Campo ◽  
Fletcher Miller ◽  
Adam Crocker
Keyword(s):  
Heat Transfer ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Small Particle ◽  
Radiative Heat ◽  
Three Dimensional ◽  
Solar Irradiation ◽  
Ansys Fluent ◽  
Solar Receiver

We present an investigation of the effects of the solar irradiation and mass flow conditions on the behavior of a Small Particle Solar Receiver employing our new, three-dimensional coupled fluid flow and radiative heat transfer model. This research expands on previous work conducted by our group and utilizes improved software with a set of new features that allows performing more flexible simulations and obtaining more accurate results. For the first time, it is possible not only to accurately predict the overall efficiency and the wall temperature distribution of the solar receiver, but also to determine the effect on the receiver of the window, the outlet tube, real solar irradiation from a heliostat field, non-cylindrical geometries and 3-D effects. This way, a much better understanding of the receiver’s capabilities is obtained. While the previous models were useful to observe simple trends, this new software is flexible and accurate enough to eventually act as a design and optimization tool for the actual receiver. The solution procedure relies on the coupling of the CFD package ANSYS Fluent to our in-house Monte Carlo Ray Trace (MCRT) software. On the one hand, ANSYS Fluent is utilized as the mass-, momentum- and energy-equation solver and requires the divergence of the radiative heat flux, which constitutes a source term of the energy equation. On the other hand, the MCRT software calculates the radiation heat transfer in the solar receiver and needs the temperature field to do so. By virtue of the coupled nature of the problem, both codes should provide feed-back to each other and iterate until convergence. The coupling between ANSYS Fluent and our in-house MCRT code is done via User-Defined Functions. After developing the mathematical model, setting up and validating the software, and optimizing the coupled solution procedure, the receiver has been simulated under fifteen different solar irradiation and mass flow rate cross combinations. Among other results, the behavior of the receiver at different times of the day and the optimum mass flow rate as a function of the solar thermal input are presented. On an average day, the thermal efficiency of the receiver is found to be over 89% and the outlet temperature over 1250 K at all times from 7:30 AM to 4:00 PM (Albuquerque, NM) by properly adapting the mass flow rate. The origin of the losses and how to improve the efficiency of the Small Particle Solar Receiver are discussed as well.

Thermodynamic Analysis of an Integrated Solar-Based Multi-Stage Flash Desalination System

2012 ◽  
Author(s):  
Diab W. Abueidda ◽  
Mohamed Gadalla
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Power Plants ◽  
Rankine Cycle ◽  
Distillation Unit ◽  
Second Law ◽  
Exergy Destruction ◽  
Steam Generation ◽  
Multi Stage

Worldwide concern about the scarcity of global water resources is increasing day by day. In Gulf countries, most power plants are co-generation power desalting plants (CPDP) that generate electric energy and also produce fresh water through the desalination of seawater. Nowadays, renewable energy provides a viable solution to the scarcity of energy resources and an environmental friendly option of global economy. In this paper, thermodynamic analyses have been performed on an integrated solar-based multi-stage flash desalination/Rankine cycle system. The respective losses as well as the first-law and second-law efficiencies for the system have been evaluated. The first-law and second-law efficiencies of the solar field were found to be 61.70% and 31.74%, respectively. The solar thermal field is based on direct steam generation method. Moreover, the mass flow rate through the Rankine cycle has been optimized to produce the maximum power. The optimal mass flow rate through the Rankine cycle found to be 51 kg/s. Furthermore, this paper presents and investigates a model of distillation plant that can use the heat rejected from the condenser of the Rankine cycle. The model is analyzed and validated with other results gained from literature. It found that the highest exergy destruction through the distillation unit occurs within the stages of the MSF unit. The percentage of exergy destruction in the MSF stages was found to be 75.41% of the total exergy destruction in the distillation unit. Additionally, this study verifies that increasing number of MSF stages decreases the percentage of exergy destruction.

Evaluation of Axial Compressor Characteristics Under Overspray Condition

2013 ◽  
Author(s):  
Chihiro Myoren ◽  
Yasuo Takahashi ◽  
Manabu Yagi ◽  
Takanori Shibata ◽  
Tadaharu Kishibe
Keyword(s):  
Gas Turbine ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Water Mass ◽  
Pressure Ratio ◽  
Axial Compressor ◽  
Test Facility ◽  
Compressor Performance ◽  
Water Mass Flow Rate

An axial compressor was developed for an industrial gas turbine equipped with a water atomization cooling (WAC) system, which is a kind of inlet fogging technique with overspray. The compressor performance was evaluated using a 40MW-class test facility for the advanced humid air turbine system. A prediction method to estimate the effect of WAC was developed for the design of the compressor. The method was based on a streamline curvature (SLC) method implementing a droplet evaporation model. Four test runs with WAC have been conducted since February 2012. The maximum water mass flow rate was 1.2% of the inlet mass flow rate at the 4th test run, while the design value was 2.0%. The results showed that the WAC decreased the inlet and outlet temperatures compared with the DRY (no fogging) case. These decreases changed the matching point of the gas turbine, and increased the mass flow rate and the pressure ratio by 1.8% and 1.1%, respectively. Since prediction results agreed with the results of the test run qualitatively, the compressor performance improvement by WAC was confirmed both experimentally and analytically. The test run with the design water mass flow rate is going to be conducted in the near future.

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