Final test results for the Schott HCE on 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.

Heat transfer analysis of receiver for large aperture parabolic trough solar collector

“…The receiver model (absorber tube surrounded by evacuated glass cover) is validated with experimental results provided by Moss et al The experiments were carried out in Sandia National Laboratory. The model is validated for LS‐2 collector with 7.5 m receiver length and 5‐m aperture diameter with UHF BC.…”

Reflector Technology Development and System Design for Concentrating Solar Power Technologies

“…[8]. Another approach is to independently test optical efficiency and receiver heat loss, and then calculate the thermal efficiency curve from these measured quantities.…”

Field Survey of Parabolic Trough Receiver Thermal Performance

“…Although a significant increase in performance of 20 to 30 percent was observed with the new Solel receivers, it was not determined whether the increased performance was entirely a result of improvements in the new receiver, or caused, in part, by degradation of the original receivers. Sandia has subsequently tested the new receivers from both Solel and Schott on the rotating platform [5]. These tests indicate that the new receivers do show significantly improved performance, however, not the 20 to 30 percent seen in the loop tests at SEGS VI.…”