Ventilator DC Fans Upgrades and Evaluation at NREL

 

Authors

Mary H. L. Anderberg — National Renewable Energy Laboratory
Ibrahim Reda — National Renewable Energy Laboratory
Manajit Sengupta — National Renewable Energy Laboratory
Afshin Michael Andreas — National Renewable Energy Laboratory
Mark Carl Kutchenreiter — National Renewable Energy Laboratory
Aron Habte — National Renewable Energy Laboratory
Mike Dooraghi — National Renewable Energy Laboratory

Category

Radiation

Description

The Atmospheric Radiation Measurement (ARM) program provides high quality radiometric data traceable to the International System of Units (SI). The National Renewable Energy Laboratory (NREL) and ARM, through the Radiometer Calibration Facility (RCF) at the Southern Great Plains (SGP) site, provide broadband radiometer calibration (BORCAL) of radiometers deployed in the SKYRAD, GNDRAD, and SIRS instrument platforms. Both NREL and ARM continue to improve radiometric measurement through the introduction of new methods to reduce uncertainty in calibrations and field measurements. This poster presents: 1) results from comparisons of modified ventilator/tracker mounting plates with various ventilator fan screen configurations, and 2) the status and results of deployment of the higher flow DC ventilator fans at the SGP RCF, and at SIRS and SKYRAD sites. For the modified tracker plate and fan screen comparison, five configurations of modified solar tracker ventilator support plates, and ventilator DC fan screens were operated at the NREL Solar Radiation Research Laboratory (SRRL) instrument deck during the 2014 and 2015 winter period. The test configurations incorporated three different plate-hole sizes, an unmodified solid plate position, two fan inlet screen sizes, and a fan operated without a screen. Results from the tests indicate virtually no significant differences in the reduction of nighttime thermal offset reductions among the five test configurations. Prior to the start of the 2014 BORCAL calibration sessions, the SGP RCF BORCAL ventilators were converted from the original Eppley AC ventilator fans to the higher flow DC fans (Delta Model FFB0812VH-T500). Following the BORCAL calibrations of the Precision Spectral Pyranometers (Eppley Model PSP), and diffuse pyranometers (Eppley Model 8-48), the DC fans were installed at ARM SIRS and SKYRAD sites when the calibrated radiometers were installed. Results from the initial DC fan evaluations at SRRL prior to March, 2014, show up to 30% reduction in IR loss errors, as well as reduced scatter in the raw signal. This is consistent with previous recommendations and investigations. Installation of the higher flow DC fans at ARM radiometry sites has resulted in the significant reduction of radiometer thermal offsets.