scholarly journals Gas Flow in Hot Porous Materials: The Solar Air Receiver and Spin-Off Applications

2006 ◽  
Author(s):  
Thomas Fend ◽  
Bernhard Hoffschmidt ◽  
Oliver Reutter ◽  
Jo¨rg Sauerhering ◽  
Robert Pitz-Paal
Keyword(s):  
Solar Radiation ◽  
Porous Materials ◽  
Gas Flow ◽  
Flow Instability ◽  
Cooling System ◽  
Cross Flow ◽  
Ceramic Materials ◽  
Turbine Cooling ◽  
Concentrated Solar Radiation ◽  
Micrometer Scale

This article presents an overview on research results from various projects, which deal with one common problem: gas flow in hot porous materials. First, the solar air receiver, which converts concentrated solar radiation into heat in an air circuit, is described as far as the basic principle and the materials employed are concerned. Then, results from experiments in concentrated solar radiation are presented. Materials employed in these applications are extruded ceramic materials as well as metal and ceramic foams with pore sizes on the milli- and micrometer scale. As it turned out, the material properties significantly influence the efficiency of the solar air receiver. It is shown, that under specific conditions flow instability occurs, which may lead to a thermal overload of the material. Measures to avoid these overloads are proposed. Two approaches how to predict gas flow theoretically are reported. Additionally, it is shown, how material quantities such as pressure drop characteristics influence the flow behaviour and the temperature distribution inside the material. Finally, before a conclusion is given, two further applications, which have been dealt with because similar phenomena occur, are reported: an advanced cross flow particle filter and a gas turbine cooling system.

scholarly journals Fabrication and performance analysis of concentrated hybrid photovoltaic system

2018 ◽  
Vol 144 ◽  
pp. 04023
Author(s):  
Krishna Murthy ◽  
Ajay Daniel ◽  
Lanvin Concessao ◽  
Habbie Alex Roy ◽  
A. Ganesha
Keyword(s):  
Solar Radiation ◽  
Waste Heat ◽  
Cooling System ◽  
Photovoltaic System ◽  
Photovoltaic Module ◽  
Performance Study ◽  
Drastic Increase ◽  
Concentrated Solar Radiation ◽  
And Performance ◽  
Set Up

Sun is the most important source of renewable source of energy. During the past few decades there has been an ever-increasing interest in Photovoltaic (PV) cells as it directly converts solar radiation into electricity. This paper involves the performance study of photovoltaic system under concentrated solar radiation. The main problem with the concentration solar energy is the drastic increase in temperature of the photovoltaic module resulting in a decrease in performance efficiency of the system. This problem of overheating of the system can be overcome by providing cooling which would ensure operation of the module in the optimal temperature range. Hence, the setup would function as a hybrid model serving the dual purpose of power generation while also utilizing the waste heat for water heating applications. The experimental set up consist of a novel arrangement of concentrator and reflector and the cooling system. The Hybrid Photovoltaic System was repeatedly tested under real time conditions on several days. A comparison was drawn between the results obtained from direct exposure of a standard photovoltaic module to that obtained from the hybrid system in order to better understand the improvement in performance parameters. The study shown a significant improvement of output of standard photovoltaic module under the concentrated solar radiation.

The Effect of Initial Cross Flow on the Cooling Performance of a Narrow Impingement Channel

2005 ◽  
Vol 127 (4) ◽  
pp. 358-365 ◽  
Author(s):  
Andrew C. Chambers ◽  
David R. H. Gillespie ◽  
Peter T. Ireland ◽  
Geoffrey M. Dailey
Keyword(s):  
Heat Transfer ◽  
Large Scale ◽  
Heat Transfer Performance ◽  
Cooling System ◽  
Cross Flow ◽  
Scale Model ◽  
Transfer Performance ◽  
Test Technique ◽  
Turbine Blade Cooling ◽  
Turbine Cooling

Impingement channels are often used in turbine blade cooling configurations. This paper examines the heat transfer performance of a typical integrally cast impingement channel. Detailed heat transfer coefficient distributions on all heat transfer surfaces were obtained in a series of low temperature experiments carried out in a large-scale model of a turbine cooling system using liquid crystal techniques. All experiments were performed on a model of a 19-hole, low aspect ratio impingement channel. The effect of flow introduced at the inlet to the channel on the impingement heat transfer within the channel was investigated. A novel test technique has been applied to determine the effect of the initial cross flow on jet penetration. The experiments were performed at an engine representative Reynolds number of 20,000 and examined the effect of additional initial cross flow up to 10 percent of the total mass flow. It was shown that initial cross flow strongly influenced the heat transfer performance with just 10 percent initial cross flow able to reduce the mean target plate jet effectiveness by 57 percent.

Cooling Performance of a Narrow Impingement Channel Including the Introduction of Cross Flow Upstream of the First Hole

2003 ◽  
Author(s):  
Andrew C. Chambers ◽  
David R. H. Gillespie ◽  
Peter T. Ireland ◽  
Geoffrey M. Dailey
Keyword(s):  
Heat Transfer ◽  
Large Scale ◽  
Cooling System ◽  
Cross Flow ◽  
Scale Model ◽  
Test Technique ◽  
Turbine Blade Cooling ◽  
Turbine Cooling ◽  
Impingement Heat Transfer ◽  
Large Scale Model

Impingement channels are often used in turbine blade cooling configurations. This paper examines the heat transfer performance of a typical integrally cast impingement channel. Detailed heat transfer coefficient distributions on all heat transfer surfaces were obtained in a series of low temperature experiments carried out in a large-scale model of a turbine cooling system using liquid crystal techniques. All experiments were performed on a model of a 19-hole, low aspect ratio impingement channel. The effect of flow introduced at the inlet to the channel on the impingement heat transfer within the channel was investigated. A novel test technique has been applied to determine the effect of the initial cross flow on jet penetration. The experiments were performed at an engine representative Reynolds number of 20,000 and examined the effect of additional initial cross flow up to 10% of the total mass flow.

scholarly journals Investigation of Solar Hybrid Electric/Thermal System with Radiation Concentrator and Thermoelectric Generator

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Edgar Arturo Chávez Urbiola ◽  
Yuri Vorobiev
Keyword(s):  
Solar Radiation ◽  
Cooling System ◽  
Electrical Energy ◽  
Thermal System ◽  
Thermoelectric Generators ◽  
Cold Side ◽  
Thermal Systems ◽  
Running Water ◽  
Concentrated Solar Radiation ◽  
Radiation Sensors

An experimental study of a solar-concentrating system based on thermoelectric generators (TEGs) was performed. The system included an electrical generating unit with 6 serially connected TEGs using a traditional semiconductor material, Bi2Te3, which was illuminated by concentrated solar radiation on one side and cooled by running water on the other side. A sun-tracking concentrator with a mosaic set of mirrors was used; its orientation towards the sun was achieved with two pairs of radiation sensors, a differential amplifier, and two servomotors. The hot side of the TEGs at midday has a temperature of around 200°C, and the cold side is approximately 50°C. The thermosiphon cooling system was designed to absorb the heat passing through the TEGs and provide optimal working conditions. The system generates 20 W of electrical energy and 200 W of thermal energy stored in water with a temperature of around 50°C. The hybrid system studied can be considered as an alternative to photovoltaic/thermal systems, especially in countries with abundant solar radiation, such as Mexico, China, and India.

scholarly journals Structure and Properties of Highly Porous Alumina-Based Ceramic Materials after Heating by Concentrated Solar Radiation

Ceramics ◽  
2021 ◽  
Vol 5 (1) ◽  
pp. 24-33
Author(s):  
Vladimir G. Babashov ◽  
Sultan Kh. Suleimanov ◽  
Mikhail I. Daskovskii ◽  
Evgeny A. Shein ◽  
Yurii V. Stolyankov
Keyword(s):  
Compressive Strength ◽  
Phase Composition ◽  
Solar Radiation ◽  
Ceramic Materials ◽  
Solar Furnace ◽  
Prolonged Treatment ◽  
Fibrous Materials ◽  
Concentrated Solar Radiation ◽  
Fusion Mode ◽  
Heating Up

Three ceramic fibrous materials of the Al2O3-SiO2 system with different densities have been treated using concentrated solar radiation. The experiment was performed using technological capabilities of the Big Solar Furnace in the 2 modes: the first mode includes heating up to 1400–1600 °C, holding for 1.5–2 h; the second mode (the fusion mode) includes heating up to 1750–1900 °C until the sample destruction, which is accompanied by fusion. Upon completion of the experiment, the phase composition, microstructure, and compressive strength of the materials were studied. It was shown that the investigated materials retained their fibrous structure under prolonged treatment in the first mode up to temperatures of 1600 °C. The phase composition of the ceramic materials changes during the experiment, and with a decrease in the density, the modification is more pronounced. Treatment of all three materials under study in the fusion mode resulted in the formation of the eutectic component in the form of spherulites. The compressive strength of the materials was found to be slightly reduced after exposure to concentrated solar radiation.

Combined Experimental and CFD Study of a HP Blade Multi-Pass Cooling System

2009 ◽  
Author(s):  
D. Jackson ◽  
P. Ireland ◽  
B. Cheong
Keyword(s):  
Heat Transfer ◽  
Film Cooling ◽  
Cooling System ◽  
Detailed Comparison ◽  
Bulk Temperature ◽  
Internal Cooling ◽  
3 Dimensional ◽  
Turbine Cooling ◽  
Cooling Hole ◽  
The Difference

Progress in the computing power available for CFD predictions now means that full geometry, 3 dimensional predictions are now routinely used in internal cooling system design. This paper reports recent work at Rolls-Royce which has compared the flow and htc predictions in a modern HP turbine cooling system to experiments. The triple pass cooling system includes film cooling vents and inclined ribs. The high resolution heat transfer experiments show that different cooling performance features are predicted with different levels of fidelity by the CFD. The research also revealed the sensitivity of the prediction to accurate modelling of the film cooling hole discharge coefficients and a detailed comparison of the authors’ computer predictions to data available in the literature is reported. Mixed bulk temperature is frequently used in the determination of heat transfer coefficient from experimental data. The current CFD data is used to compare the mixed bulk temperature to the duct centreline temperature. The latter is measured experimentally and the effect of the difference between mixed bulk and centreline temperature is considered in detail.

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