Thermal Model of a Solar Thermochemical Reactor for Metal Oxide Reduction

2020 ◽  
Vol 142 (5) ◽  
Author(s):  
Bo Wang ◽  
Lifeng Li ◽  
Johannes J. Pottas ◽  
Roman Bader ◽  
Peter B. Kreider ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Metal Oxide ◽  
Reduction Rate ◽  
Incident Radiation ◽  
Maximum Temperature ◽  
Transfer Model ◽  
Oxide Reduction ◽  
Solar Simulator ◽  
Metal Oxide Reduction ◽  
Solar Thermochemical

Abstract A transient heat transfer model is developed to study the thermal performance of a high-temperature solar thermochemical reactor for metal oxide reduction. The solar reactor consists of an indirectly irradiated tubular fluidized bed contained in a solar cavity receiver. Radiative heat transfer in the cavity, modeled with the Monte Carlo ray-tracing method, is coupled to conduction in the tube and cavity walls. Incident radiation distributions from a diffuse radiative source and a high-flux solar simulator are implemented separately in the model to study the influence of incident radiation directionality on the performance of the reactor. Maximum temperature, maximum thermal stress, start-up time, energy balance, and particle reduction rate for the proposed reactor concept are calculated to inform the design and optimization of a prototype reactor.

THERMAL MODELLING OF A SOLAR THERMOCHEMICAL REACTOR FOR METAL OXIDE REDUCTION

2018 ◽  
Author(s):  
Bo Wang ◽  
Vincent M. Wheeler ◽  
Johannes Pottas ◽  
Peter B. Kreider ◽  
Wojciech Lipinski
Keyword(s):  
Metal Oxide ◽  
Thermal Modelling ◽  
Oxide Reduction ◽  
Metal Oxide Reduction ◽  
Solar Thermochemical

A Two-Dimensional Conjugate Heat Transfer Model for Forced Air Cooling of an Electronic Device

1989 ◽  
Vol 111 (1) ◽  
pp. 41-45 ◽  
Author(s):  
A. Zebib ◽  
Y. K. Wo
Keyword(s):  
Heat Transfer ◽  
Conjugate Heat Transfer ◽  
Electronic Device ◽  
Transfer Problem ◽  
Maximum Temperature ◽  
Transfer Model ◽  
Air Cooling ◽  
Two Dimensional ◽  
Component Design ◽  
Forced Air

Thermal analysis of forced air cooling of an electronic component is modeled as a two-dimensional conjugate heat transfer problem. The velocity field in a constricted channel is first computed. Then, for a typical electronic module, the energy equation is solved with allowance for discontinuities in the thermal conductivity. Variation of the maximum temperature with the average air velocity is presented. The importance of our approach in evaluating possible benefits due to changes in component design and the limitations of the two-dimensional model are discussed.

Combined Conduction and Radiation Heat Transfer in Porous Materials Heated by Intense Solar Radiation

1985 ◽  
Vol 107 (1) ◽  
pp. 29-34 ◽  
Author(s):  
L. K. Matthews ◽  
R. Viskanta ◽  
F. P. Incropera
Keyword(s):  
Heat Transfer ◽  
Radiation Heat Transfer ◽  
Plane Layer ◽  
Single Scattering ◽  
Dominant Mode ◽  
Radiative Properties ◽  
Maximum Temperature ◽  
Transfer Model ◽  
Radiation Heat ◽  
Flux Approximation

An analysis is presented to predict the heat transfer characteristics of a plane layer of a semitransparent, high-temperature, porous material which is irradiated by an intense solar flux. A transient, combined conduction and radiation heat transfer model, which is based on a two-flux approximation for the radiation, is used to predict the temperature distribution and heat transfer in the material. Numerical results have been obtained using thermophysical and radiative properties of zirconia as a typical material. The results show that radiation is an important mode of heat transfer, even when the opacity of the material is large (τL > 100). Radiation is the dominant mode of heat transfer in the front third of the material and comparable to conduction toward the back. The semitransparency and high single scattering albedo of the zirconia combine to produce a maximum temperature in the interior of the material.

Cooling of Concentrator Photovoltaic Cells Using Mini-Scale Jet Impingement Heat Sinks

2018 ◽  
Author(s):  
Ali Radwan ◽  
Meshack Hawi ◽  
Mahmoud Ahmed
Keyword(s):  
Heat Transfer ◽  
Flow Model ◽  
Three Dimensional ◽  
Jet Impingement ◽  
Heat Sinks ◽  
Maximum Temperature ◽  
Transfer Model ◽  
Cell Temperature ◽  
Maximum Cell ◽  
T System

In this study, an efficient cooling technique for concentrator photovoltaic (CPV) cells is proposed to enhance the system electrical efficiency and extend its lifetime. To do this, a comprehensive three-dimensional conjugate heat transfer model of CPV cells layers coupled with the heat transfer and fluid flow model inside jet impingement heat sink is developed. Four different jet impingement designs are compared. The investigated designs are (A) central inlet jet, (B) Hypotenuse inlet jet, (C) staggered inlet jet, and (D) conventional jet impingement design with side drainage. The effect of coolant flowrate on the CPV/T system performance is investigated. The model is numerically simulated and validated using the available experiments. The performance of CPV system is investigated at solar concentration ratios of 20 and coolant flowrate up to 6000g/min. It is found that increasing the flowrate from 60 g/min to 600 g/min decrease the maximum cell temperature by 31°C for the configuration D while increasing the flowrate from 600 g/min to 6000 g/min reduce the cell temperature by 20.2°C. It is also concluded that at a higher flowrate of 6000g/min, all the investigated configurations relatively achieve better temperature uniformity with maximum temperature differences of 0.9 °C, 2.1 °C, 3.6 °C, and 3.9 °C for configurations A, B, C, and D respectively.

scholarly journals Nonuniform Heat Transfer Model and Performance of Molten Salt Cavity Receiver

Energies ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 1001
Author(s):  
Jianfeng Lu ◽  
Yarong Wang ◽  
Jing Ding
Keyword(s):  
Heat Transfer ◽  
Molten Salt ◽  
Thermal Efficiency ◽  
Radiation Flux ◽  
Incident Radiation ◽  
Heat Transfer Model ◽  
Experimental Result ◽  
Transfer Model ◽  
Fluid Temperature ◽  
Primary Role

The temperature distribution and thermal efficiency of a molten salt cavity receiver are investigated by a nonuniform heat transfer model based on thermal resistance analysis. For the cavity receiver MSEE in Sandia National Laboratories, thermal efficiency in this experiment is about 87.5%, and the calculation value of 86.93–87.79% by a present nonuniform model fits very well with the experimental result. Different from the uniform heat transfer model, the receiver surface temperature in the nonuniform heat transfer model is remarkably higher than the backwall temperature. The incident radiation flux plays a primary role in thermal performance of cavity receiver, and thermal efficiency approaches to maximum under optimal incident radiation flux. In order to increase thermal efficiency, various methods are proposed and studied, including heat convection enhancement by an increase of flow velocity or the decrease of the tube diameter and number of tubes in the panel, and heat loss decline by a decrease of view factor, surface emissivity and insulation conductivity. According to calculation results by different modes of the nonuniform heat transfer model, the thermal efficiency of the cavity receiver is reduced by nonuniform heat transfer caused by variable fluid temperature or variable circumferential temperature, so thermal efficiency calculated by variable fluid temperature and variable circumferential temperature is lower than that calculated by average fluid temperature and bilateral uniform circumferential temperature for 0.86%.

Performance Study of a Bi-Directional Thermodiode Designed for Energy-Efficient Buildings

2002 ◽  
Vol 124 (3) ◽  
pp. 291-299 ◽  
Author(s):  
Wongee Chun ◽  
Kuan Chen ◽  
Hyung Taek Kim
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Energy Efficient ◽  
Onset Time ◽  
Incident Radiation ◽  
Maximum Temperature ◽  
Performance Study ◽  
Energy Efficient Buildings ◽  
Diode System ◽  
Shading Device

A new, bi-directional thermodiode designed for energy-efficient buildings was constructed and tested. Experimental results are presented and discussed for solar-heating applications. The thermodiode system consisted of a number of rectangular loops filled with water. The tilting angle of the loops can be altered to reverse the direction of natural convection within the loops for bi-directional operations. The horizontal segments of the loops were attached to metallic panels facing indoors or outdoors. The amount of thermal radiation incident on the outdoor-facing surfaces can be adjusted by rotating the panels or by installing a removable shading device in front of the surfaces. Results of the indoor tests for winter use of the diode showed an onset time between 7 to 20 min for natural convection to be induced throughout the loops in the thermodiode. Before the throughflow started, the fluid in the heated copper tubes reached its maximum temperature. A sudden drop and rebound in this temperature was observed immediately after the onset of throughflow. After that, temperatures at different locations on the thermodiode rose at approximately the same rate until a steady state was reached. During the cool-down phase, the temperatures decreased at the same rate without humps, indicating only conduction took place in the rectangular loops when the thermodiode was reverse-biased. A simple analytical model was developed to estimate the temperature variations and heat transfer rates in the diode system. The diode under forward-biased condition increases the heat transfer rate by nearly 100 times for an incident radiation of 600 W/m2.

Feasibility of Using Polypropylene for Metal Oxide Reduction

JOM ◽  
2019 ◽  
Vol 71 (11) ◽  
pp. 3923-3930
Author(s):  
M. Cumbul Altay ◽  
S. Eroglu
Keyword(s):  
Metal Oxide ◽  
Oxide Reduction ◽  
Metal Oxide Reduction
Sign in / Sign up

Export Citation Format

Share Document