Time filter

Source Type

Dezhou, China

Xu F.,North China University of Technology | Liang W.,Himin Solar Energy Group
11th International Conference on Control, Automation, Robotics and Vision, ICARCV 2010 | Year: 2010

The aiming accuracy of the optical axis of a heliostat directly affects the working efficiency of a concentrating solar tower plant. Due to the size of heliostat, it is difficult to measure the orientation of the optical axis directly during the tracking process. With a computer-vision based measuring system, the center of reflecting beam of a heliostat can be detected, but the result is disturbed by internal and external interferences. This paper presents a method to estimate the orientation of optical axis of a tracking heliostat using unscented kalman filter based on the measured beam center data. Simulation results and estimations based on actual measurements are presented in the paper. ©2010 IEEE. Source

Li J.,Chinese Academy of Sciences | Wang Z.,Chinese Academy of Sciences | Lei D.,Chinese Academy of Sciences | Li J.,Himin Solar Energy Group
Solar Energy | Year: 2012

Hydrogen gas formed by the thermal decomposition of organic heat transfer fluids can permeate through parabolic trough receiver tubes into the vacuum annulus, leading to significant heat losses in the receiver which reduces the parabolic trough power plant efficiency. This problem is quite important as these systems are being developed to drive down the cost of electricity. Thus, hydrogen permeation in parabolic trough power plants must be understood to develop strategies to reduce or prevent hydrogen gas accumulation in the receiver annulus. Hydrogen permeation model for parabolic trough receivers was developed based on measurements of hydrogen permeability of solar-selective coatings. The model was then used to study the effects of the hydrogen generation rate, the hydrogen pressure in the receiver tubes and the hydrogen barrier coating on the hydrogen permeation into the annulus. The hydrogen generation rate plays a significant role in the hydrogen permeation process, with the hydrogen pressure, permeability and adsorb area all related to balancing the hydrogen permeation rate with the hydrogen generation rate. © 2012 Elsevier Ltd. Source

Xu L.,CAS Institute of Electrical Engineering | Xu L.,University of Chinese Academy of Sciences | Wang Z.,CAS Institute of Electrical Engineering | Yuan G.,CAS Institute of Electrical Engineering | And 2 more authors.
Solar Energy | Year: 2012

A new study on testing thermal performance of all-glass evacuated solar collectors with the air as heat transfer fluid under dynamic conditions outdoors has been developed. The model of this dynamic method was established with the energy balance analysis on solar collectors of this type. Compared with the first order model under steady-state conditions, this model can characterize thermal efficiency of solar collectors under more extensive conditions, reducing considerable operating time spent in waiting for the right test conditions. Through the derivation of the proposed model, it proved a strong relationship existed between this model and the first order model mentioned above. The dynamic model projection for the outlet temperatures was in good agreement with the measured result. © 2012 Elsevier Ltd. Source

Liu J.,North China Institute of Aerospace Engineering | Lei D.,CAS Institute of Electrical Engineering | Li Q.,Himin Solar Energy Group
Renewable Energy | Year: 2016

The vacuum characteristics and lifetime are the key problems of parabolic trough receiver. Heat loss of the receiver will greatly increase when the vacuum has been lost. Especially, if hydrogen is inside the annulus space of the receiver, heat loss at a level is approximately a factor of four higher than the loss for a receiver with good vacuum. Suitable vacuum levels and residual gases should be maintained in the receiver to ensure performances during its projected lifetime. In this paper, the variations of composition and partial pressure of residual gases with temperature in the receiver were measured by a high sensitivity quadrupole mass spectrometer gas analyzer. The effects of residual gas and getter on the vacuum lifetime of receiver were analyzed. The results showed that hydrogen was the main residual gas in the annular space of receiver without getter, and the nitrogen was the main gas released in the receiver with getter. It can be confirmed that the residual gas analysis was a very effective way to predict and evaluate the vacuum lifetime of the receiver. © 2015 Elsevier Ltd. Source

Lu Z.S.,Shanghai JiaoTong University | Wang R.Z.,Shanghai JiaoTong University | Xia Z.Z.,Shanghai JiaoTong University | Lu X.R.,Himin Solar Energy Group | And 3 more authors.
Renewable Energy | Year: 2013

One two-phase thermo-syphon silica gel-water solar adsorption chiller and LiBr-H 2O absorption chiller with new medium CPC (Compound Parabolic Concentrator) solar collectors were investigated. The reliability of adsorption chiller can be improved, because there is only one vacuum valve in this innovative design. Medium temperature evacuated-tube CPC solar collectors were firstly utilized in the LiBr-H 2O air conditioning system. The former system was applied in north of China at Latitude 37.45° (Dezhou city, China), the latter system was applied at Latitude 36.65° (Jinan city, China). Experimental results showed that the adsorption chiller can be powered by 55 °C of hot water. The adsorption chiller can provide 15 °C of chilled water from 9:30 to 17:00, the average solar COP (COPs) of the system is 0.16. In the absorption cooling system, the efficiency of the medium temperature evacuated-tube CPC solar collector can reach 0.5 when the hot water temperature is 125 °C. The absorption chiller can provide 15 °C of chilled water from 11:00 to 15:30, and the average solar COPs of absorption system is 0.19. © 2012. Source

Discover hidden collaborations