Thermal Evaluation of Receivers in Parabolic Trough Collectors using Airborne Infrared Imaging

Abstract

Besides the optical efficiency thermal efficiency is one key aspect when designing and operating a concentrated solar power plant. Using parabolic trough collectors, a large part of the thermal losses occurs because of aging and degradation of different parts of the receivers. Therefore, replacing faulty receivers in time is crucial for maintaining a high overall degree of efficiency. The state-of-the-art measuring methods to determine the thermal status of receivers are time consuming and require a large amount of work in the field. This thesis presents Q-Fly-Thermo, a thermal performance measuring system developed for high measuring speed and minimal effort in the field, to classify the receivers of a plant with respect to their thermal state. Based on the Q-Fly system, Q-Fly-Thermo uses a GPS controlled drone with an infrared camera for analysis. Defect receivers are visible in infrared images because heat losses increase the glass envelope temperature. A software was developed to analyze the images from the airborne infrared camera. It can determine which receivers appear in the images, analyze their thermal status and classify intact and faulty ones. First tests of the system are presented and the results are compared with an independent measuring method. Based on the experience made the reliability and optimization potential are assessed.