Experimental Analysis of Overall Thermal Properties of Parabolic Trough Receivers

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
Eckhard Lüpfert ◽  
Klaus-J. Riffelmann ◽  
Henry Price ◽  
Frank Burkholder ◽  
Tim Moss
Keyword(s):  
Thermal Properties ◽  
Experimental Analysis ◽  
Operating Temperature ◽  
Field Measurements ◽  
Heat Losses ◽  
Thermal Loss ◽  
Parabolic Trough ◽  
Energy Balances ◽  
Good Agreement ◽  
Glass Envelope

The heat loss of a receiver in a parabolic trough collector plays an important role in collector performance. A number of methods have been used to measure the thermal loss of a receiver tube depending on its operating temperature. This paper presents methods for measuring receiver heat losses including field measurements and laboratory setups both based on energy balances from the hot inside of the receiver tube to the ambient. Further approaches are presented to measure and analyze the temperature of the glass envelope of evacuated receivers and to model overall heat losses and emissivity coefficients of the receiver. Good agreement can be found between very different approaches and independent installations. For solar parabolic trough plants operating in the usual 390°C temperature range, the thermal loss is around 300W∕m receiver length.

Heat Loss Measurement and Analyses of Solar Parabolic Trough Receiver

2013 ◽  
Vol 291-294 ◽  
pp. 127-131
Author(s):  
Jian Feng Lu ◽  
Jing Ding ◽  
Jian Ping Yang ◽  
Kang Wang
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Heat Loss ◽  
Boundary Region ◽  
Heat Losses ◽  
Experimental Measurements ◽  
Wind Condition ◽  
Parabolic Trough ◽  
Loss Measurement ◽  
Glass Envelope

The heat loss of vacuum receiver plays critical important role in solar parabolic trough system. In this paper, experimental measurements and calculation models were conducted to investigate the heat loss of solar parabolic trough receiver with receiver length of 10.2 m and diameter of 0.120 m. In general, the heat loss of receiver decreased with the receiver wall temperature, while it can approach minimum under special wind condition. The heat loss of receiver mainly included the heat loss of glass and boundary region, and the heat losses of receiver, glass region and boundary region with tube temperatures of 176.2oC were respectively 987.1 W, 762.2 W and 224.9 W. Outside the glass envelope, the convection and radiation both play an important role in the heat loss of receiver, while the heat transfer is mainly dependent upon the radiation inside the glass envelope. In addition, the heat losses of convection outside the glass and radiation inside the glass from calculation very well agreed with the experimental data.

scholarly journals A Transient Thermography Method to Separate Heat Loss Mechanisms in Parabolic Trough Receivers

2013 ◽  
Vol 136 (1) ◽  
Author(s):  
Marc Röger ◽  
Peter Potzel ◽  
Johannes Pernpeintner ◽  
Simon Caron
Keyword(s):  
Heat Loss ◽  
Temperature Measurements ◽  
Thermal Excitation ◽  
Transient Method ◽  
Parabolic Trough ◽  
Selective Coating ◽  
Transient Thermography ◽  
Energy Balances ◽  
Glass Envelope ◽  
Loss Mechanisms

This paper describes a transient thermography method to measure the heat loss of parabolic trough receivers and separate their heat loss mechanisms. This method is complementary to existing stationary techniques, which use either energy balances or glass envelope temperature measurements to derive overall heat losses. It is shown that the receiver heat loss can be calculated by applying a thermal excitation on the absorber tube and measuring both absorber tube and glass envelope temperature signals. Additionally, the emittance of the absorber selective coating and the vacuum quality of the annulus can be derived. The benefits and the limits of the transient method are presented and compared to the established stationary method based on glass envelope temperature measurements. Simulation studies and first validation experiments are described. A simulation based uncertainty analysis indicates that an uncertainty level of approximately 5% could be achieved on heat loss measurements for the transient method introduced in this paper, whereas for a conventional stationary field measurement technique, the uncertainty is estimated to 17–19%.

Impact of Gas-Filled Annular Space on Thermal and Optical Performances of a Heat Pipe Parabolic Trough Solar Collector

2021 ◽  
Vol 143 (6) ◽  
Author(s):  
Moulay Ahmed Janan ◽  
Mohamed Taqi ◽  
Hamid Chakir
Keyword(s):  
Heat Pipe ◽  
Solar Collector ◽  
Critical Value ◽  
Heat Losses ◽  
Inert Gas ◽  
Annular Space ◽  
Parabolic Trough ◽  
Parabolic Trough Solar Collector ◽  
Helium Neon ◽  
Glass Envelope

Abstract In this work, we demonstrate the improvement of thermal performances of a heat pipe parabolic trough solar collector by optimizing the annulus space, between the evaporator and the glass envelope, and using an appropriate filling gas. We compared the system thermal effectiveness for nine filling gases (hydrogen, air, helium, neon, oxygen, nitrogen, argon, krypton, and xenon). The results showed that using xenon or krypton leads to the best thermal yield (70%). While krypton arises to be the most energetically efficient filling gas, argon, with a thermal yield of 62%, presents a best compromise as the cheapest inert gas. In addition, we showed that the annular space size should be less than a critical value to minimize heat losses and to reduce the material cost during manufacturing.

Parabolic Trough Receiver Thermal Testing

2007 ◽  
Author(s):  
Frank Burkholder ◽  
Michael Brandemuehl ◽  
Henry Price ◽  
Judy Netter ◽  
Chuck Kutscher ◽  
...  
Keyword(s):  
Heat Loss ◽  
Operating Temperature ◽  
Thermal Testing ◽  
Published Data ◽  
Thermal Loss ◽  
Performance Parameters ◽  
Parabolic Trough ◽  
Receiver Performance ◽  
The Difference ◽  
Indoor And Outdoor

NREL has fabricated a parabolic trough receiver thermal loss test stand to quantify parabolic receiver off-sun steadystate heat loss. At an operating temperature of 400°C, measurements on Solel UVAC2 and Schott PTR70 receivers suggest off-sun thermal losses of approximately 370 W/m receiver length. For comparison, a receiver from the field with hydrogen in its annulus loses approximately 1000 W/m receiver length. The UVAC2 heat loss results agree within measurement uncertainty to previously published data, while the PTR70 results are somewhat higher than previously published data. The sensitivity of several receiver performance parameters is considered and it is concluded that differences in indoor and outdoor testing cannot account for the difference in PTR70 thermal loss results.

Innovative energy and mass balance of a continuous evaporating crystallizer

2019 ◽  
pp. 646-654
Author(s):  
Jan Iciek ◽  
Kornel Hulak ◽  
Radosław Gruska
Keyword(s):  
Energy Balance ◽  
Mass Balance ◽  
Working Conditions ◽  
Crystallization Process ◽  
Heat Losses ◽  
Inert Gas ◽  
Gas Removal ◽  
Energy Balances ◽  
Heat Released ◽  
Mass And Energy Balances

The article presents the mass and energy balances of the sucrose crystallization process in a continuous evaporating crystallizer. The developed algorithm allows to assess the working conditions of the continuous evaporating crystallizers and the technological and energy parameters. The energy balance algorithm takes into account the heat released during the crystallization of sucrose, which was analyzed in this study, heat losses to the environment and heat losses due the vapor used for inert gas removal.

Thermal performance comparison of different sun tracking configurations

2019 ◽  
Vol 88 (2) ◽  
pp. 20902
Author(s):  
O. Achkari ◽  
A. El Fadar
Keyword(s):  
Thermal Performance ◽  
Electricity Generation ◽  
Arid Regions ◽  
Performance Comparison ◽  
Water Desalination ◽  
Parabolic Trough ◽  
Parabolic Trough Collector ◽  
The Impact ◽  
The Mathematical Model ◽  
Good Agreement

Parabolic trough collector (PTC) is one of the most widespread solar concentration technologies and represents the biggest share of the CSP market; it is currently used in various applications, such as electricity generation, heat production for industrial processes, water desalination in arid regions and industrial cooling. The current paper provides a synopsis of the commonly used sun trackers and investigates the impact of various sun tracking modes on thermal performance of a parabolic trough collector. Two sun-tracking configurations, full automatic and semi-automatic, and a stationary one have numerically been investigated. The simulation results have shown that, under the system conditions (design, operating and weather), the PTC's performance depends strongly on the kind of sun tracking technique and on how this technique is exploited. Furthermore, the current study has proven that there are some optimal semi-automatic configurations that are more efficient than one-axis sun tracking systems. The comparison of the mathematical model used in this paper with the thermal profile of some experimental data available in the literature has shown a good agreement with a remarkably low relative error (2.93%).

Analysis of Tempering and Rehardening for Grinding of Hardened Steels

1991 ◽  
Vol 113 (4) ◽  
pp. 388-394 ◽  
Author(s):  
O. B. Fedoseev ◽  
S. Malkin
Keyword(s):  
Thermal Properties ◽  
Heat Source ◽  
Hardened Steel ◽  
Temperature History ◽  
Hardness Distribution ◽  
Temperature Dependent ◽  
Thermally Activated ◽  
Reaction Equations ◽  
Rate Controlling Step ◽  
Good Agreement

An analysis is presented to predict the hardness distribution in the subsurface of hardened steel due to tempering and rehardening associated with high temperatures generated in grinding. The grinding temperatures are modeled with a triangular heat source at the grinding zone and temperature-dependent thermal properties. The temperature history, including the effect of multiple grinding passes, is coupled with thermally activated reaction equations for tempering and for reaustenitization which is the rate controlling step in rehardening. Experimental results from the literature are found to be in good agreement with the analytical predictions.

Preparation and Thermal Properties of High-Purified Molten Nitrate Salt Materials with Heat Transfer and Storage

2015 ◽  
Vol 34 (8) ◽  
Author(s):  
Hongtao Zhang ◽  
Youjing Zhao ◽  
Jingli Li ◽  
Lijie Shi ◽  
Min Wang
Keyword(s):  
Heat Transfer ◽  
Thermal Stability ◽  
Thermal Properties ◽  
Molten Salts ◽  
Operating Temperature ◽  
Nitrate Salt ◽  
Solar Salt ◽  
And Storage ◽  
Thermal Stability Of ◽  
Operating Temperature Range

AbstractThis paper focuses on thermal stability of molten salts, operating temperature range and latent heat of molten salts at a high temperature. In this experiment, multi-component molten salts (purified Solar Salt) composed of purified NaNO

The Application of Ground-airborne TEM Systems for Underground Cavity Detection in China

2018 ◽  
Vol 23 (1) ◽  
pp. 103-113
Author(s):  
Guo-qiang Xue ◽  
Xiu Li ◽  
Sheng-bao Yu ◽  
Wei-ying Chen ◽  
Yan-ju Ji
Keyword(s):  
Three Dimensional ◽  
Field Measurements ◽  
Cavity Detection ◽  
Vector Finite Element Method ◽  
Military Applications ◽  
Vector Finite Element ◽  
Survey Results ◽  
Tem Method ◽  
Central Loop ◽  
Good Agreement

Ground-based, electrical-source, and UAV-borne receiver TEM configurations have previously been used to map mines in Jiangsu Province, China. In this study, the EM responses of air-filled mine tunnels were simulated by using a three-dimensional (3D) vector finite element method. A new apparent resistivity formula has been proposed for the ground-airborne TEM configuration. In the study area, field measurements were carried out along 36 profiles for the ground-airborne TEM and 16 profiles for ground TEM. The ground-airborne TEM results were determined to be in good agreement with the ground TEM survey results using a surface central loop, and were also consistent with the known geologic conditions. The experiment was successful and showed that a ground-ground-airborne TEM method could potentially become a novel alternative for both future civilian and military applications. [Figure: see text]

Solar Orbiter observations of solar wind current sheets and their deHoffman-Teller frames

2021 ◽  
Author(s):  
Konrad Steinvall ◽  
Yuri Khotyaintsev ◽  
Giulia Cozzani ◽  
Andris Vaivads ◽  
Christopher Owen ◽  
...  
Keyword(s):  
Solar Wind ◽  
Electric Field ◽  
Wind Velocity ◽  
Solar Wind Velocity ◽  
Field Measurements ◽  
Velocity Measurements ◽  
Current Sheets ◽  
Spacecraft Orbit ◽  
Electric Field Measurements ◽  
Good Agreement

<p>Solar wind current sheets have been extensively studied at 1 AU. The recent advent of Parker Solar Probe and Solar Orbiter (SolO) has enabled us to study these structures at a range of heliocentric distances.</p><p>We present SolO observations of current sheets in the solar wind at heliocentric distances between 0.55 and 0.85 AU, some of which show signatures of ongoing magnetic reconnection. We develop a method to find the deHoffman-Teller frame which minimizes the Y-component (the component tangential to the spacecraft orbit) of the electric field. Using the electric field measurements from RPW and magnetic field measurements from MAG, we use our method to determine the deHoffman-Teller frame of solar wind current sheets. The same method can also be used on the Alfvénic turbulence and structures found in the solar wind to obtain a measure of the solar wind velocity.</p><p>Our preliminary results show a good agreement between our modified deHoffmann-Teller analysis based on the single component E-field, and the conventional deHoffman-Teller analysis based on 3D plasma velocity measurements from PAS. This opens up the possibility to use the RPW and MAG data to obtain an estimate of the solar wind velocity when particle data is unavailable.</p>

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