Transient Three-Dimensional Heat Transfer Model of a Solar Thermochemical Reactor for H2O and CO2 Splitting via Nonstoichiometric Ceria Redox Cycling

2013 ◽  
Author(s):  
Justin Lapp ◽  
Wojciech Lipiński
Keyword(s):  
Heat Transfer ◽  
Heat Recovery ◽  
Fuel Efficiency ◽  
Three Dimensional ◽  
Reactor Design ◽  
Heat Transfer Model ◽  
Heat Fluxes ◽  
Transfer Model ◽  
Rotating Cylinders ◽  
Solar Receiver

A transient heat transfer model is developed for a solar reactor prototype for H2O and CO2 splitting via two-step non-stoichiometric ceria cycling. Counter-rotating cylinders of reactive and inert materials cycling between high and low temperature zones permit continuous operation and heat recovery. To guide the reactor design a transient three-dimensional heat transfer model is developed based on transient energy conservation, accounting for conduction, convection, radiation, and chemical reactions. The model domain includes the rotating cylinders, a solar receiver cavity, and insulated reactor body. Radiative heat transfer is analyzed using a combination of the Monte Carlo method, Rosseland diffusion approximation, and the net radiation method. Quasi-steady state distributions of temperatures, heat fluxes, and the non-stoichiometric coefficient are reported. Ceria cycles between temperatures of 1708 K and 1376 K. A heat recovery effectiveness of 28% and solar-to-fuel efficiency of 5.2% are predicted for an unoptimized reactor design.

Transient Three-Dimensional Heat Transfer Model of a Solar Thermochemical Reactor for H2O and CO2 Splitting Via Nonstoichiometric Ceria Redox Cycling

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
Justin Lapp ◽  
Wojciech Lipiński
Keyword(s):  
Heat Transfer ◽  
Heat Recovery ◽  
Fuel Efficiency ◽  
Radiation Heat Transfer ◽  
Three Dimensional ◽  
Heat Transfer Model ◽  
Heat Fluxes ◽  
Transfer Model ◽  
Solar Thermochemical ◽  
Solar Receiver

A transient three-dimensional heat transfer model is developed for a 3 kWth solar thermochemical reactor for H2O and CO2 splitting via two-step nonstoichiometric ceria cycling. The reactor consists of a windowed solar receiver cavity, counter-rotating reactive and inert cylinders, and insulated reactor walls. The counter-rotating cylinders allow for continuous fuel production and heat recovery. The model is developed to solve energy conservation equations accounting for conduction, convection, and radiation heat transfer modes, and chemical reactions. Radiative heat transfer is analyzed using a combination of the Monte Carlo ray-tracing method, the net radiation method, and the Rosseland diffusion approximation. Steady-state temperatures, heat fluxes, and nonstoichiometry are reported. A temperature swing of up to 401 K, heat recovery effectiveness of up to 95%, and solar-to-fuel efficiency of up to 5% are predicted in parametric studies.

scholarly journals Fast three-dimensional heat transfer model for computing internal temperatures in the bearing housing of automotive turbochargers

2018 ◽  
Vol 21 (8) ◽  
pp. 1286-1297 ◽  
Author(s):  
Antonio Gil ◽  
Andrés Omar Tiseira ◽  
Luis Miguel García-Cuevas ◽  
Tatiana Rodríguez Usaquén ◽  
Guillaume Mijotte
Keyword(s):  
Heat Transfer ◽  
Coke Formation ◽  
Three Dimensional ◽  
Heat Transfer Model ◽  
Operating Conditions ◽  
Thermal Design ◽  
Working Fluid ◽  
Transfer Model ◽  
Lumped Model ◽  
Bearing System

Each of the elements that make up the turbocharger has been gradually improved. In order to ensure that the system does not experience any mechanical failures or loss of efficiency, it is important to study which engine-operating conditions could produce the highest failing rate. Common failing conditions in turbochargers are mostly achieved due to oil contamination and high temperatures in the bearing system. Thermal management becomes increasingly important for the required engine performance. Therefore, it has become necessary to have accurate temperature and heat transfer models. Most thermal design and analysis codes need data for validation; often the data available fall outside the range of conditions the engine experiences in reality leading to the need to interpolate and extrapolate disproportionately. This article presents a fast three-dimensional heat transfer model for computing internal temperatures in the central housing for non-water cooled turbochargers and its direct validation with experimental data at different engine-operating conditions of speed and load. The presented model allows a detailed study of the temperature rise of the central housing, lubrication channels, and maximum level of temperature at different points of the bearing system of an automotive turbocharger. It will let to evaluate thermal damage done to the system itself and influences on the working fluid temperatures, which leads to oil coke formation that can affect the performance of the engine. Thermal heat transfer properties obtained from this model can be used to feed and improve a radial lumped model of heat transfer that predicts only local internal temperatures. Model validation is illustrated, and finally, the main results are discussed.

Development of a Three-Dimensional Heat Transfer Model for Continuous Annealing of Steel Strip

2011 ◽  
Vol 51 (4) ◽  
pp. 1790-1795 ◽  
Author(s):  
N. Depree ◽  
M. P. Taylor ◽  
J. J. J. Chen ◽  
J. Sneyd ◽  
S. Taylor ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Steel Strip ◽  
Three Dimensional ◽  
Heat Transfer Model ◽  
Continuous Annealing ◽  
Transfer Model

Nonuniform heat transfer model and performance of parabolic trough solar receiver

Energy ◽  
2013 ◽  
Vol 59 ◽  
pp. 666-675 ◽  
Author(s):  
Jianfeng Lu ◽  
Jing Ding ◽  
Jianping Yang ◽  
Xiaoxi Yang
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Model ◽  
Transfer Model ◽  
Parabolic Trough ◽  
And Performance ◽  
Solar Receiver

Modeling of Steel Slab Reheating Process in a Walking Beam Reheating Furnace

2016 ◽  
Author(s):  
Guangwu Tang ◽  
Arturo Saavedra ◽  
Tyamo Okosun ◽  
Bin Wu ◽  
Chenn Q. Zhou ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Three Dimensional ◽  
Heat Transfer Model ◽  
Furnace Operation ◽  
Production Data ◽  
Heating Process ◽  
Transfer Model ◽  
Transfer Coefficients ◽  
Reheating Furnace ◽  
Reheating Process

Slab reheating is a very important step in steel product manufacturing. A small improvement in reheating efficiency can translate into big savings to steel mills in terms of fuel consumption and productivity. Computational fluid dynamics (CFD) has been employed in conducting numerical simulations of the slab reheating furnace operation. However, a full industrial scale three-dimensional (3D) simulation of a slab reheating furnace, while comprehensive, is not an efficient way to conduct broad studies of the slab heating process. In this paper, a comprehensive two-dimensional (2D) numerical heat transfer model for slab reheating in a walking beam furnace was developed using the finite difference method. The 2D heat transfer model utilizes the heat transfer coefficients derived from a 3D reheating furnace CFD model which was validated by using mill instrumented slab trials. The 2D heat transfer model is capable of predicting slab temperature evolutions during the reheating processes based on the real time furnace conditions and steel physical properties. The 2D model was validated by using mill instrumented slab trials and production data. Good agreement between the model predictions and production data was obtained.

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