scholarly journals Heat flux and temperature measurements on glass envelope and bellows of parabolic trough receivers

2018 ◽  
Author(s):  
Simon Caron ◽  
Marc Röger ◽  
Johannes Pernpeintner
Keyword(s):  
Heat Flux ◽  
Temperature Measurements ◽  
Parabolic Trough ◽  
Glass Envelope

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%.

Flow, thermal structure, and subglacial conditions of a surge-type glacier

1984 ◽  
Vol 21 (2) ◽  
pp. 232-240 ◽  
Author(s):  
Garry K. C. Clarke ◽  
Sam G. Collins ◽  
David E. Thompson
Keyword(s):  
Energy Source ◽  
Heat Flux ◽  
Thermal Structure ◽  
Drainage System ◽  
Temperature Measurements ◽  
Bottom Temperature ◽  
Water Percolation ◽  
Geothermal Flux

Temperature measurements in a subpolar surge-type glacier reveal a distinctive thermal structure associated with the boundary between the ice reservoir and receiving areas. In the receiving area the glacier is cold based, but bottom temperature has increased as much as 0.5 °C between 1981 and 1982, and the basal heat flux is roughly 10 times the expected geothermal flux. Water percolation through permeable subglacial material is the probable energy source. Deformation of the substrate could destroy this drainage system and trigger a surge.

scholarly journals Characterization and Corrections for Clamp-On Fluid Temperature Measurements in Turbulent Flows

2018 ◽  
Vol 10 (3) ◽  
Author(s):  
Bijan Nouri ◽  
Marc Röger ◽  
Nicole Janotte ◽  
Christoph Hilgert
Keyword(s):  
Fluid Flow ◽  
Turbulent Flows ◽  
Power Plants ◽  
Measurement Data ◽  
Temperature Measurements ◽  
Correction Function ◽  
Acceptance Testing ◽  
Fluid Temperature ◽  
Parabolic Trough ◽  
Operation Conditions

A clamp-on measurement system for flexible and accurate fluid temperature measurements for turbulent flows with Reynolds numbers higher than 30,000 is presented in this paper. This noninvasive system can be deployed without interference with the fluid flow while delivering the high accuracies necessary for performance and acceptance testing for power plants in terms of measurement accuracy and position. The system is experimentally validated in the fluid flow of a solar thermal parabolic trough collector test bench, equipped with built-in sensors as reference. Its applicability under industrial conditions is demonstrated at the 50 MWel AndaSol-3 parabolic trough solar power plant in Spain. A function based on large experimental data correcting the temperature gradient between the measured clamp-on sensor and actual fluid temperature is developed, achieving an uncertainty below ±0.7 K (2σ) for fluid temperatures up to 400 °C. In addition, the experimental results are used to validate a numerical model. Based on the results of this model, a general dimensionless correction function for a wider range of application scenarios is derived. The clamp-on system, together with the dimensionless correction function, supports numerous combinations of fluids, pipe materials, insulations, geometries, and operation conditions and should be useful in a variety of industrial applications of the power and chemical industry where temporal noninvasive fluid temperature measurement is needed with good accuracy. The comparison of the general dimensionless correction function with measurement data indicates a measurement uncertainty below 1 K (2σ).

Performance analysis of Parabolic Trough Collectors with Double Glass Envelope

2019 ◽  
Vol 130 ◽  
pp. 1092-1107 ◽  
Author(s):  
Julian D. Osorio ◽  
Alejandro Rivera-Alvarez
Keyword(s):  
Performance Analysis ◽  
Parabolic Trough ◽  
Glass Envelope

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.

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