Majedul Islam

Development of Empirical Equations for Irradiance Profile of a Standard Parabolic Trough Collector Using Monte Carlo Ray Tracing Technique

This article explains a technique in which equations are developed to produce the irradiance profile around the receiver of LS2 collector using a vigorouslyverified MCRT model. A large range of test conditions including daily normal insolation, selective coatings and glass envelop conditions were chosen from the published data by Dudley et al. [1] for the job. The R2 value is excellent that varies between 0.9857 and 0.9999. Therefore, these equations can be used confidently to produce boundary heat flux profile of the collector at normal incident for conjugate heat transfer analyses of the receiver.

A method of three dimensional thermo-fluid simulation of the receiver of a standard parabolic trough collector

A parabolic trough collector (PTC) is the most proven concentrating collector system for indirect steam generation in solar thermal power plants. The receiver of the collector is fabricated enveloping a metal absorber tube using an evacuated glass tube. Depending on the level of evacuation, the glass envelope reduces the convection heat loss from the tube almost to zero. However, sometimes the envelopes are broken, damaged or removed that causes potential convection loss from an open-to-air receiver tube. On the other hand, the solar irradiance profile around the receiver tube is likely to be highly nonuniform. In order to study the heat transfer mechanism of an exposed receiver tube of a standard PTC under the actual optical and environmental conditions, a 3-dimensional Computational Conjugate Heat Transfer (CCHT) model of the receiver tube was developed. The CCHT model was developed applying finite volume technique of computational fluid dynamics integrating with a verified Monte Carlo ray tracing optical model. The CCHT model was verified extensively, and different heat loss models were developed to investigate the heat loss characteristics. The convection heat loss from the outer surface of the receiver tube was observed very high as it was exposed to a high-temperature gradient with its surroundings. Therefore, it is obvious that the receiver tube should be enveloped and evacuated properly. A well-managed and efficiently operated PTC solar energy field could be the best candidate for sustainable energy management for a sustainable future.