Abstract

The imminent optical and thermal challenges associated with the parabolic trough collector (PTC) has made the application of the technology to be unattractive. Obviously, the immanent thermal stress emanating from an uneven concentration of solar irradiance on the absorber tube (AT), which triggers the optical challenge, misalignment of AT from the PTC focal axis. The expectancy to increase the application of this technology, has instigated the present work to initiate the application of equispaced fins within the AT as the means of eliminating the thermal stress and increasing the exit fluid temperature without interfering with the optical and thermal efficiencies of the PTC. Thus, the design equations for the fin characteristics dimensions were developed. The simulated fin dimensions were in good agreement with the measured data. The enormous advantages of using equispaced fins is to increase the number of transfer unit (NTU) and the effectiveness of the PTC, with higher exit fluid temperature, if the AT outer diameter is maintained within the nominal diameter range (0.04 < 𝑑abo< 0.07𝑚), the uninterrupted performance of the PTC is guaranteed.
Also, the introduction of equispaced fins in the AT will serve as a remedy to the thermal stress and its enormous consequences. Moreover, for a safe operation of the PTC; (Tabsorber-Tfluid, out) < (Tfluid, out-Tfluid, in), without embarking on distant air monitoring. Also, this work recommends for the computational fluid dynamics (CFD) simulation of the innovative absorber (air-solar-finned absorber) for its validity, which is out of scope of this work.