Test Results of a Schott HCE Using a LS-2 Collector

Abstract

Sandia National Laboratories has completed thermal performance testing on the Schott parabolic trough receiver using the LS-2 collector on the Sandia rotating platform at the National Solar Thermal Test Facility in Albuquerque, NM. This testing was funded as part of the US DOE Sun-Lab USA-Trough program. The receiver tested was a new Schott receiver, known as Heat Collector Elements (HCEs). Schott is a new manufacturer of trough HCEs. The Schott HCEs are 4m long; therefore, two were joined and mounted on the LS-2 collector module for the test. The Schott HCE design consists of a 70mm diameter high solar absorptance coated stainless steel (SS) tube encapsulated within a 125mm diameter Pyrex® glass tube with vacuum in the annulus formed between the SS and glass tube to minimize convection heat losses. The Schott HCE design is unique in two regards. First, the bellows used to compensate for the difference in thermal expansion between the metal and glass tube are inside the glass envelope rather than outside. Second, the composition of materials at the glass-to-metal seal has very similar thermal expansion coefficients making the joint less prone to breakage from thermal shock. Sandia National Laboratories provided both the azimuth and elevation collector module tracking systems used during the tests. The test results showed the efficiency of the Schott HCE to be very similar to current HCEs being manufactured by Solel. This testing provided performance verification for the use of Schott tubes with Solargenix trough collector assemblies at currently planned trough power plant projects in Arizona and Nevada.

Numerical investigation of thermal performance of heat loss of parabolic trough receiver

“…Due to the small difference in temperature between fluid and wall adjacent to it, the fluid temperature is considered to be identical to the absorber temperature [3][4][5].…”

“…The latter method has also been used to evaluate the heat loss of HCE based on the quasi-steady state theory in refs. [3,4] and some conclusions have been made. Because of the inconvenience of the latter method refs.…”

“…The existing experiments and simulations have only focused on some tests of external factors such as constant wind velocity and different temperature difference T [1][2][3][4][5]8,9] and less considered about the modeling heat transfer process of HCE, let alone the following problems: (1) influence of different selective coatings property on heat loss of HCE; (2) influence of different annular pressures on heat loss of HCE; (3) influence of different wind velocities on heat loss of HCE.…”

Heat-Loss Testing of Solel's UVAC3 Parabolic Trough Receiver

“…Figure 7 shows that the UVAC3 receiver has significantly less heat loss than the UVAC2 receiver. Convention has been to present receiver heat-loss data as a function of the temperature difference between the heat-transfer fluid temperature and ambient temperature [3,4] or the temperature difference between the average absorber temperature and the ambient temperature [2]. Heat losses from evacuated receivers are dominated by radiation heat transfer from the hot absorber surface.…”

Assess the Efficacy of an Aerial Distant Observer Tool Capable of Rapid Analysis of Large Sections of Collector Fields: FY 2008 CSP Milestone Report, September 2008

“…The VSHOT provides detailed characterization of the surface figure of concentrator modules but does not differentiate optical misalignments relative to the receiver. Researchers at Sandia National Laboratories found the DO method to be difficult and not feasible for what they were trying to accomplish [2,3], namely, to translate measurements directly into specifications for mirror mounting adjustment (as provided by the TOP alignment instrument). For DO-1, qualitative data that specify where problems exist would be a tremendous asset, so that TOP alignment could know exactly where to emphasize its work.…”