Coupled Fluid Flow and Radiation Modeling of a Cylindrical Small Particle Solar Receiver

2012 ◽  
Author(s):  
Adam Crocker ◽  
Fletcher Miller
Keyword(s):  
Cylinder Wall ◽  
Outlet Temperature ◽  
Gas Temperature ◽  
Dynamics Modeling ◽  
Ansys Fluent ◽  
Data Output ◽  
Gaussian Fit ◽  
Radiation Modeling ◽  
Solar Receiver ◽  
Initial Results

This research expands on previous work by coupling the in-house Monte Carlo Ray Trace (MCRT) radiation model with the more sophisticated fluid dynamics modeling capabilities of ANSYS FLUENT. This allows for the inclusion of more realistic inlet and outlet geometries in the receiver, as well as a turbulence model and much finer grid sizing. Taken together, these features give a more complete picture of the heat transfer, mixing, and temperature profiles within the receiver than previous models. This flow solution is coupled to the MCRT code, by using the in-house MCRT radiation solver to provide the source term of the energy equation. The temperature data output from FLUENT is then fed back into the FORTRAN MCRT code, via a User Defined Function written in C#, and the two models iterate until convergence. The solar input has been modified from the previous model to provide a Gaussian fit to a calculated flux distribution, which is more realistic than a uniform flux. Initial results for a 5 MW solar input agree with the trend identified in Ruther’s work regarding the influence of particle mass loading on heating in the receiver. The maximum outlet temperature reached is 1430K, which is on target for driving a Brayton cycle gas turbine. Cylinder wall temperatures are consistently below those of the gas boundary layer, and significantly below the maximum gas temperature in the receiver cavity.

scholarly journals Structural Analysis of a Direct Heated Tubular Solar Receiver for Supercritical CO2 Brayton Cycle

2015 ◽  
Author(s):  
Jesus D. Ortega ◽  
Joshua M. Christian ◽  
Clifford K. Ho
Keyword(s):  
Thermal Stresses ◽  
Structural Model ◽  
Structural Integrity ◽  
Permanent Deformation ◽  
Creep Model ◽  
Outlet Temperature ◽  
Ansys Fluent ◽  
Future Design ◽  
Pressure Load ◽  
Solar Receiver

Closed-loop super-critical carbon dioxide (sCO2) Brayton cycles are being evaluated in combination with concentrating solar power to provide higher thermal-to-electric conversion efficiencies relative to conventional steam Rankine cycles. However, high temperatures (650–700°C) and pressures (20–25 MPa) are required in the solar receiver. In this study, an extensive material review was performed along with a tube size optimization following the ASME Boiler and Pressure Vessel Code and B31.1 and B313.3 codes respectively. Subsequently, a thermal-structural model was developed using ANSYS Fluent and Structural to design and analyze the tubular receiver that could provide the heat input for a ∼2 MWth plant. The receiver will be required to provide an outlet temperature of 650°C (at 25 MPa) or 700°C (at 20 MPa). The induced thermal stresses were applied using a temperature gradient throughout the tube while a constant pressure load was applied on the inner wall. The resulting stresses have been validated analytically using constant surface temperatures. The cyclic loading analysis was performed using the Larson-Miller creep model in nCode Design Life to define the structural integrity of the receiver over the desired lifetime of ∼10,000 cycles. The results have shown that the stresses induced by the thermal and pressure load can be withstood by the tubes selected. The creep-fatigue analysis displayed the damage accumulation due to the cycling and the permanent deformation of the tubes. Nonetheless, they are able to support the required lifetime. As a result, a complete model to verify the structural integrity and thermal performance of a high temperature and pressure receiver has been developed. This work will serve as reference for future design and evaluation of future direct and indirect tubular receivers.

scholarly journals Aiming Strategy on a Prototype-Scale Solar Receiver: Coupling of Tabu Search, Ray-Tracing and Thermal Models

2021 ◽  
Vol 13 (7) ◽  
pp. 3920
Author(s):  
Benjamin Grange ◽  
Gilles Flamant
Keyword(s):  
Tabu Search ◽  
Ray Tracing ◽  
Wall Temperature ◽  
Gradual Increase ◽  
Particle Temperature ◽  
Outlet Temperature ◽  
Operation Conditions ◽  
Start Up ◽  
Fluidized Particle ◽  
Solar Receiver

An aiming point strategy applied to a prototype-scale power tower is analyzed in this paper to define the operation conditions and to preserve the lifetime of the solar receiver developed in the framework of the Next-commercial solar power (CSP) H2020 project. This innovative solar receiver involves the fluidized particle-in-tube concept. The aiming solution is compared to the case without the aiming strategy. Due to the complex tubular geometry of the receiver, results of the Tabu search for the aiming point strategy are combined with a ray-tracing software, and these results are then coupled with a simplified thermal model of the receiver to evaluate its performance. Daily and hourly aiming strategies are compared, and different objective normalized flux distributions are applied to quantify their influence on the receiver wall temperature distribution, thermal efficiency and particle outlet temperature. A gradual increase in the solar incident power on the receiver is analyzed in order to keep a uniform outlet particle temperature during the start-up. Results show that a tradeoff must be respected between wall temperature and particle outlet temperature.

Analysis and Modelling of the Transient Thermal Behaviour of Automotive Turbochargers

2013 ◽  
Author(s):  
Richard D. Burke
Keyword(s):  
Internal Combustion Engines ◽  
Operating Conditions ◽  
Outlet Temperature ◽  
Thermally Stable ◽  
Gas Temperature ◽  
Side Peak ◽  
Warm Up ◽  
Thermal Transients ◽  
Modeling Approaches ◽  
Stable Conditions

Turbochargers are a key technology to deliver fuel consumption reductions on future internal combustion engines. However, the current industry standard modeling approaches assume the turbine and compressor operate under adiabatic conditions. Although some state of the art modeling approaches have been presented for simulating the thermal behavior, these have focused on thermally stable conditions. In this work, an instrumented turbocharger was operated on a 2.2L Diesel engine and in parallel a one-dimensional lumped capacity thermal model was developed. For the first time this paper presents analysis of experimental and modeling results under dynamic engine operating conditions. Engine speed and load conditions were varied to induce thermal transients with turbine inlet temperatures ranging from 200–800°C; warm-up behavior from 25°C ambient was also studied. Following a model tuning process based on steady operating conditions, the model was used to predict turbine and compressor gas outlet temperatures, doing so with an RMSE of 8.4°C and 7.1°C respectively. On the turbine side, peak heat losses from the exhaust gases were observed to be up to double those observed under thermally stable conditions due to the heat accumulation in the structure. During warm-up, the model simplifications did not allow for accurate modeling of compressor, however on the turbine side gas temperature predictions errors were reduced from 150°C to around 40°C. The main benefits from the present modeling approach appear to be in turbine outlet temperature prediction, however modeling improvements are identified for future work.

Computational Analysis of Cryogenic Stirling Refrigerator

2019 ◽  
Author(s):  
G.-R. Domenikos ◽  
P. Bitsikas ◽  
E. Rogdakis
Keyword(s):  
Gas Temperature ◽  
Similar System ◽  
Ansys Fluent ◽  
One Dimensional ◽  
Helium 4 ◽  
Fluent Software ◽  
Computational Fluid Dynamics Cfd ◽  
Pass Through ◽  
Stirling Refrigerator ◽  
Two Machines

Abstract In the present work, a system consisting of two combined cryocoolers is simulated with the use of Computational Fluid Dynamics (CFD) and ANSYS Fluent software. The cryocoolers operate with frequency of 1 Hz and at temperature below 1 K. Instead of a matrix containing a regenerator, each of the machines employs a recuperator. The two recuperators exchange heat with each other, combining thus the two machines into one system. The working gas of the cryocoolers is helium-3 (He-3), the properties of which are obtained by the available literature for cryogenic temperatures. The setup of the presented simulation is based on a one-dimensional (1D) analytical model. The model is used to describe conducted experiments, in which ideal He-3 is the working gas of a similar system of Stirling cryocoolers and superfluid helium-4 (He-4) can pass through the pistons (super leak). The simulations results, including the fluctuation of gas temperature in the machine’s spaces, pressure drop, work and heat exchanged are presented.

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.

Experimental and Simulation Study on the Effects of Twisted Coil Plates on the Performance of Fire Tube Boiler

2014 ◽  
Vol 564 ◽  
pp. 234-239
Author(s):  
M.K. Roslim ◽  
Suhaimi Hassan ◽  
K. Izzati
Keyword(s):  
Flue Gas ◽  
Operating Time ◽  
Width Ratio ◽  
Gas Temperature ◽  
Steam Temperature ◽  
Ansys Fluent ◽  
Boiler Efficiency ◽  
Twist Ratio ◽  
Fluent Simulation ◽  
Tube Coil

Influences of twisted coil plate insert on the performance of fire tube boiler using were experimentally investigated. In this study, the twisted coil plate was placed inside the tube to illustrate boiler performance. The performances of boiler were studied in terms of operating time taken, exhaust flue gas temperature, steam temperature and boiler efficiency. The boiler was operated with 50%, 100% and without tube coil plate inserts at low and high fire burner setting. Based on the results obtained, effect of twisted plate insert and without insert were observed. There is an enhancement in boiler performance in terms of boiler efficiency. The ANSYS Fluent simulation showed the effect of width ratio and twist ratio. Therefore, the experimental results indicate that using twisted coil plate in the boiler is one of the best ways to improve boiler performance.

scholarly journals CFD Analysis of Auditorium using Ansys Fluent

2019 ◽  
Vol 8 (2) ◽  
pp. 4533-4538
Keyword(s):  
Air Conditioning ◽  
Fluid Dynamic ◽  
Winter Season ◽  
Building Design ◽  
Project Work ◽  
Outlet Temperature ◽  
Hvac System ◽  
Computational Fluid Dynamic Analysis ◽  
Ansys Fluent ◽  
Conditioning Equipment

The primary aspect of any building design and management is heating, ventilation and air conditioning (HVAC). Such systems play very important role in building construction and then the comfort of the occupants of buildings. Hence proper design of such HVAC system is necessary and is essential for efficient and green buildings the HVAC equipment perform the duty of heating and/ or cooling for residential and commercial buildings. Such HVAC system also provide fresh outdoor air to dilute the air contaminants such as odor from occupants of buildings, volatile organic compounds , chemicals etc. Air conditioning equipment is one of the major components in HVAC system. In the project work, an effort has been made to analyses the HVAC system used in seminar halls of which have sitting capacity of 100 people. It is very much essential to have comfortless for people participating in events like seminar, conferences, commercial presentations in seminar hall. Good cooling of seminar hall is essential especially in summer season and moderate warmness is necessary in winter season. In sitting arrangements, the 10 chairs are arranged in 10 rows. The Computational Fluid Dynamic analysis of HVAC system available in seminar hall is carried out by using ANSYS FLUENT software both summer and winter seasons. Parameter studies have been carried out by varying inlet velocity of air in the range 0.1 to 0.5 m/s. the results have been presented in the form of velocity, pressure and temperature contours. As it is observed that as inlet air velocity increases from 0.1 to 0.5 m/s. the outlet temperature decreases from 307 to 302K.

scholarly journals Effect of Multi-Walled Carbon Nanotubes-Based Nanofluids on Marine Gas Turbine Intercooler Performance

Nanomaterials ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 2300
Author(s):  
Salah Almurtaji ◽  
Naser Ali ◽  
Joao A. Teixeira ◽  
Abdulmajid Addali
Keyword(s):  
Carbon Nanotubes ◽  
Gas Turbine ◽  
Thermophysical Properties ◽  
Outlet Temperature ◽  
Gas Temperature ◽  
Pumping Power ◽  
Turbine Engine ◽  
Compressed Gas ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

Coolants play a major role in the performance of heat exchanging systems. In a marine gas turbine engine, an intercooler is used to reduce the compressed gas temperature between the compressor stages. The thermophysical properties of the coolant running within the intercooler directly influence the level of enhancement in the performance of the unit. Therefore, employing working fluids of exceptional thermal properties is beneficial for improving performance in such applications, compared to conventional fluids. This paper investigates the effect of utilizing nanofluids for enhancing the performance of a marine gas turbine intercooler. Multi-walled carbon nanotubes (MWCNTs)-water with nanofluids at 0.01–0.10 vol % concentration were produced using a two-step controlled-temperature approach ranging from 10 °C to 50 °C. Next, the thermophysical properties of the as-prepared suspensions, such as density, thermal conductivity, specific heat capacity, and viscosity, were characterized. The intercooler performance was then determined by employing the measured data of the MWCNTs-based nanofluids thermophysical properties in theoretical formulae. This includes determining the intercooler effectiveness, heat transfer rate, gas outlet temperature, coolant outlet temperature, and pumping power. Finally, a comparison between a copper-based nanofluid from the literature with the as-prepared MWCNTs-based nanofluid was performed to determine the influence of each of these suspensions on the intercooler performance.

scholarly journals ПОВЫШЕНИЕ ТОЧНОСТИ РАСЧЕТА ПОЛЯ ТЕМПЕРАТУР ГАЗА НА ВЫХОДЕ ИЗ КАМЕРЫ СГОРАНИЯ ГТД МЕТОДОМ ТРЕХМЕРНОГО КОМПЬЮТЕРНОГО МОДЕЛИРОВАНИЯ

2020 ◽  
pp. 74-82
Author(s):  
Сергей Анатольевич Евсеев ◽  
Дмитрий Викторович Козел ◽  
Игорь Федорович Кравченко
Keyword(s):  
Numerical Experiment ◽  
Combustion Chamber ◽  
Turbulence Model ◽  
Schmidt Number ◽  
Temperature Pattern ◽  
Gas Temperature ◽  
Ansys Fluent ◽  
Maximum Value ◽  
Turbulent Schmidt Number ◽  
Initial Settings

The problem of numerical simulation of the gas flow with the combustion of atomized liquid fuel was solved (the equilibrium combustion model pdf was used along with the partially mixed mixture model) in the annular combustion chamber of a gas turbine engine. Numerical modeling was performed in Ansys Fluent calculation complex. The purpose of the calculations was to simulate the radial and circumferential unevenness of the gas temperature pattern at the outlet of the combustion chamber. As a result of the calculations, it was found that the accuracy of modeling the radial and circumferential unevenness of the gas temperature pattern at the outlet of the combustion chamber is unsatisfactory when using the k–e turbulence model with the initial settings for the Ansys Fluent calculation complex. Moreover, the maximum value of the radial non-uniformity of the gas temperature pattern at the outlet of the combustion chamber exceeded the value obtained in the experiment by 12.61 %, and the maximum value of the circumferential non-uniformity by 12.69 %. To improve the accuracy of modeling the temperature pattern non-uniformity at the outlet of the combustion chamber, a numerical experiment was conducted to study the effect of the degree of turbulent diffusion of gas components on the value of temperature pattern non-uniformity. To reduce the non-uniformity of the temperature pattern at the outlet of the combustion chamber, the degree of turbulent diffusion of gas components was increased with respect to the initial version of the calculation, performed using the k–e model of turbulence with the initial settings for the Ansys Fluent calculation complex, by reducing the turbulent Schmidt number Sc in the turbulence model. For the initial settings of the k–e turbulence model in the Ansys Fluent calculation complex, the turbulent Schmidt number Sc = 0.85. A numerical experiment was performed for the values of Sc = 0.6, Sc = 0.4, and Sc = 0.2. The results of a numerical experiment confirmed the influence of the turbulent Schmidt number Sc on the result of calculating the gas temperature pattern at the outlet of the combustion chamber; as the value of Sc decreases, the level of the circumferential and radial non-uniformities of the gas temperature pattern decreases. However, the degree of reduction of radial and circumferential irregularities with a decrease in Sc is different. Therefore, to ensure high accuracy in calculating both the circumferential and radial non-uniformities of the gas temperature pattern, it was proposed to use a variable value of the turbulent Schmidt number Sc depending on the gas temperature instead of a constant value. The functional dependence of the turbulent Schmidt number Sc on the gas temperature was implemented in the Ansys Fluent calculation complex using the user function (UDF). The results of modeling the gas temperature pattern using the proposed UDF function for the turbulent Schmidt number Sc are in satisfactory agreement with the experimental data for both radial and circumferential non-uniformities of the gas temperature pattern at the outlet of the combustion chamber.

scholarly journals A Numerical Study for a Double Twisted Tube Heat Exchanger

2021 ◽  
Vol 39 (5) ◽  
pp. 1583-1589
Author(s):  
Ali K. Abdul Razzaq ◽  
Khudheyer S. Mushatet
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Numerical Study ◽  
Hot Water ◽  
Flow Mode ◽  
Outer Diameter ◽  
Outlet Temperature ◽  
Ansys Fluent ◽  
Tube Heat Exchanger ◽  
Twisted Tube

The thermal and fluid physiognomies of a double twisted tube heat exchanger was examined numerically. Twisted engineering is a wide-use method to improve heat transfer in heat exchangers. A counter-flow mode utilizing hot water in the inner tube and cold air in the outer tube was considered. This study aims to progress the thermal performance of the double tube heat exchanger by using twisted tubes instead of plane tubes. The heat exchanger was (1m) length, outer diameter (0.05m) and inner diameter (0.025m), both with a thickness (0.004m). It was tested for different values of twist ratios (Tr= 5, 10, and 15 respectively) and Reynolds numbers (Re=5000 to 30000). The Navier - Stockes and energy equations besides the turbulence model in demand for modelling this physical problem. ANSYS Fluent code was used for the numerical simulation. The results showed that the twisted tube heat exchanger showed increasing heat transfer compared with a plain tube heat exchanger. It was found that the cold outlet temperature, pressure drop and effectiveness are increased as the twist ratio increases.

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