Assessment of a Computationally Efficient Method for Industrial Simulations of Transient Heat Transfer During Autoclave Curing

2021 ◽  
Author(s):  
Iacopo Catalani ◽  
Francesco Balduzzi ◽  
Stefano Mariani ◽  
Giovanni Ferrara ◽  
Alessandro Bianchini
Keyword(s):  
Heat Transfer ◽  
Steady State ◽  
Computational Cost ◽  
Numerical Approach ◽  
Curing Temperature ◽  
Transient Heat Transfer ◽  
Computationally Efficient ◽  
It Industry ◽  
Autoclave Curing ◽  
Cfd Analyses

Abstract A numerical approach for transient CFD analyses of autoclave curing process is presented, aimed at finding a trade-off between accuracy and computational cost that can make it industry-affordable. A steady-state, conjugated heat transfer (CHT) analysis is carried out for the simultaneous simulation of solid and fluid regions to obtain a spatial distribution of the heat-transfer coefficient (HTC). This distribution and the curing temperature diagram are then used as boundary conditions for a transient heat-transfer simulation of the solid parts only. Results are compared to both experiments and coupled fluid-solid steady-state CHT simulations, proving that the proposed methodology is accurate and less computationally expensive than a fully-coupled, fluid-solid simulation.

Simulation of Unsteady Turbomachinery Flows Using an Implicitly Coupled Nonlinear Harmonic Balance Method

2011 ◽  
Author(s):  
Jonathan M. Weiss ◽  
Venkataramanan Subramanian ◽  
Kenneth C. Hall
Keyword(s):  
Steady State ◽  
Harmonic Balance ◽  
Time Derivative ◽  
Computational Cost ◽  
Harmonic Balance Method ◽  
Balance Method ◽  
Computationally Efficient ◽  
State Equations ◽  
Approximate Factorization ◽  
Efficient Manner

A nonlinear harmonic balance method for the simulation of turbomachinery flows is presented. The method is based on representing an unsteady, time periodic flow by a Fourier series in time and then solving a set of mathematically steady-state equations to obtain the Fourier coefficients. The steady-state solutions are stored at discrete time levels distributed throughout one period of unsteadiness and are coupled via the physical time derivative and at periodic boundaries. Implicit coupling between time levels is achieved in a computationally efficient manner through approximate factorization of the linear system that results from the discretized equations. Unsteady, rotor-stator interactions are performed to validate the implementation. Results based on the harmonic balance method are compared against those obtained using a full unsteady, time-accurate calculation using moving meshes. The implicitly coupled nonlinear harmonic balance method is shown to produce a solution of reasonable accuracy compared to the full unsteady approach but with significantly less computational cost.

scholarly journals Heat Exhaustion

2002 ◽  
Vol 124 (07) ◽  
pp. 50
Keyword(s):  
Heat Transfer ◽  
Steady State ◽  
Catalytic Cracking ◽  
Slide Valve ◽  
Refining Process ◽  
Cooling Time ◽  
Transient Heat Transfer ◽  
Heat Exhaustion ◽  
Fluidized Catalytic Cracking ◽  
Operating Temperatures

This article focuses on fluidized catalytic cracking, which is a slide valve that controls the catalyst flow in hydrocarbon refining process. The valves are typically installed in refractory lined piping approximately 5 feet in diameter. Operating temperatures inside the valve range from 900°F to 1,400°F and, occasionally, go as high as 1800°F. Replacements require a shutdown that can run into days just for cooling time and then reheating. A major Houston-based manufacturer of slide valves, Tapco International, came up with a design that would eliminate bolts to make the valve last longer. The company asked BES Engineering of Houston to analyze the stresses due to steady-state and transient heat transfer, and to evaluate their effects. Tapco has about two dozen of the boltless valves in the field. The reliability of the new design can save hundreds of thousands of dollars by eliminating unscheduled shutdowns and unexpected maintenance.

STEADY-STATE AND TRANSIENT HEAT TRANSFER PHENOMENA OF WATER: AN EXPERIMENTAL AND THEORETICAL INVESTIGATION AT NEAR-CRITICAL PRESSURES

2018 ◽  
Author(s):  
Tobias Gschnaidtner ◽  
Andreas Kohlhepp ◽  
Gerrit A. Schatte ◽  
Christoph Wieland ◽  
Hartmut Spliethoff
Keyword(s):  
Heat Transfer ◽  
Steady State ◽  
Theoretical Investigation ◽  
Transient Heat Transfer

Experimental Investigation of Steady State and Transient Heat Transfer in a Radial Turbine Wheel of a Turbocharger

2015 ◽  
Author(s):  
Hailu Tadesse ◽  
Christian Rakut ◽  
Mathias Diefenthal ◽  
Manfred Wirsum ◽  
Tom Heuer
Keyword(s):  
Heat Transfer ◽  
Thermal Stress ◽  
Steady State ◽  
Transient Heat Transfer ◽  
Inlet Temperature ◽  
Boost Pressure ◽  
Turbine Inlet Temperature ◽  
Temperature Level ◽  
Turbine Wheel ◽  
Turbine Inlet

Turbochargers make an essential contribution to the development of efficient combustion engines by increasing the boost pressure. In recent years, there has been a trend towards enhanced turbine inlet temperatures, which cause heat fluxes within the turbocharger. Due to the high rotational speed, the centrifugal force and thermal stress of the turbine components rise inevitably. In addition to the enhanced temperature level, due to the variation of the load and speed of the engine in cold start, acceleration and deceleration periods, the turbine inlet temperature is changing permanently, which leads to higher thermal loads. The flow state and thus the heat transfer in the turbocharger are constantly changing within a single cycle. This induces an unsteady temperature profile, which is essential for the thermal stress and thus the prediction of the component life cycle. The present study reports about the results of the experimental steady state and transient heat transfer investigations of a turbocharger which are conducted at a hot gas test rig. The investigations are performed transiently between different steady state operating points. In order to simulate the real driving conditions, the turbine inlet temperature is changed between a high and low temperature level abruptly (thermal shock) or cyclically at an approximately constant mass flow. The flow parameters at the inlet and outlet of the turbine as well as material and surface temperatures of the turbine wheel and casing are recorded. Additionally the compressor as well as the bearing housing inlet and outlet conditions are measured. The heat flux between the components is analyzed by means of the measured data.

scholarly journals Study of Triangular Fuzzy Hybrid Nanofluids on the Natural Convection Flow and Heat Transfer between Two Vertical Plates

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Muhammad Nadeem ◽  
Ahmed Elmoasry ◽  
Imran Siddique ◽  
Fahd Jarad ◽  
Rana Muhammad Zulqarnain ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Volume Fraction ◽  
Computational Cost ◽  
Numerical Approach ◽  
Hybrid Nanoparticles ◽  
Convection Flow ◽  
Hybrid Nanofluid ◽  
Parallel Plates ◽  
Highly Nonlinear

The prime objective of the current study is to examine the effects of third-grade hybrid nanofluid with natural convection utilizing the ferro-particle Fe 3 O 4 and titanium dioxide TiO 2 and sodium alginate (SA) as a host fluid, flowing through vertical parallel plates, under the fuzzy atmosphere. The dimensionless highly nonlinear coupled ordinary differential equations are computed adopting the bvp4c numerical approach. This is an extremely effective technique with a low computational cost. For validation, it is found that as the volume fraction of Fe 3 O 4 + TiO 2 hybrid nanoparticles rises, so does the heat transfer rate. The current and existing results with their comparisons are shown in the form of the tables. The present findings are in good agreement with their previous numerical and analytical results in a crisp atmosphere. The nanoparticles volume fraction of Fe 3 O 4 and TiO 2 is taken as uncertain parameters in terms of triangular fuzzy numbers (TFNs) [0, 0.05, 0.1]. The TFNs are controlled by α − cut and the variability of the uncertainty is studied through triangular membership function (MF).

Transient Heat Transfer From a Horizontal Cylinder in the Low-Reynolds-Number Flow of Helium Gas

2002 ◽  
Author(s):  
Qiusheng Liu ◽  
Katsuya Fukuda ◽  
Koichi Hata
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Steady State ◽  
Heat Input ◽  
Low Reynolds Number ◽  
Horizontal Cylinder ◽  
Transient Heat Transfer ◽  
Quasi Steady State ◽  
Helium Gas ◽  
Low Reynolds

The knowledge of forced convection transient heat transfer at various periods of exponentially increasing heat input to a heater is important as a database for understanding the transient heat transfer process in a high temperature gas cooled reactor (HTGR) due to an accident in excess reactivity. In this study, the transient heat transfer coefficients for Helium gas flowing perpendicular to a horizontal cylinder were measured in the low-Reynolds-number region. The platinum heater with a diameter of 1.0 mm was heated by electric current with an exponentially increasing heat input of Q0exp(t/τ). It was clarified that the heat transfer coefficient approaches the quasi-steady-state one for the period τ over around 1 s, and it becomes higher for the period of τ shorter than about 1 s. The transient heat transfer shows less dependent on the gas flowing velocity when the period becomes very short. Based on the experimental data, the ratio of transient heat transfer to the quasi-steady-state one was correlated as a function of Reynolds number of the gas flow and the non-dimensional period of increasing heat input. For the non-dimensional period larger than about 300, the transient heat transfer approaches the steady-state one, and shows no dependence on the Reynolds number.

scholarly journals The curled wake model: a three-dimensional and extremely fast steady-state wake solver for wind plant flows

2021 ◽  
Vol 6 (2) ◽  
pp. 555-570
Author(s):  
Luis A. Martínez-Tossas ◽  
Jennifer King ◽  
Eliot Quon ◽  
Christopher J. Bay ◽  
Rafael Mudafort ◽  
...  
Keyword(s):  
Steady State ◽  
Wind Power ◽  
Power Plants ◽  
Stokes Equations ◽  
Computational Cost ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Computationally Efficient ◽  
Mean Power ◽  
Wake Model

Abstract. Wind turbine wake models typically require approximations, such as wake superposition and deflection models, to accurately describe wake physics. However, capturing the phenomena of interest, such as the curled wake and interaction of multiple wakes, in wind power plant flows comes with an increased computational cost. To address this, we propose a new hybrid method that uses analytical solutions with an approximate form of the Reynolds-averaged Navier–Stokes equations to solve the time-averaged flow over a wind plant. We compare results from the solver to supervisory control and data acquisition data from the Lillgrund wind plant obtaining wake model predictions which are generally within 1 standard deviation of the mean power data. We perform simulations of flow over the Columbia River Gorge to demonstrate the capabilities of the model in complex terrain. We also apply the solver to a case with wake steering, which agreed well with large-eddy simulations. This new solver reduces the time – and therefore the related cost – it takes to simulate a steady-state wind plant flow (on the order of seconds using one core). Because the model is computationally efficient, it can also be used for different applications including wake steering for wind power plants and layout optimization.

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