Minghuan Guo

The Optical Designing Method and the Concentrating Performance Analysis for a Toroidal Heliostat with Spinning-Elevation Sun Tracking

A practical optical designing method for and some optical simulation results of a toroidal surface heliostat with the two axis spinning-elevation sun tracking are presented in this paper, which will be used as a concentrator for a hydrogen generation system. As a prototype, this heliostat has a compound toroidal surface, which is composed of the 16 same toroidal mirror facets of 1 meter width and 1 meter height with the focal length 7.4689 meters, and the design concentration power of the heliostat is 6 kilowatts. The sampling ray-tracing method including the solar disk effect is introduced and used to analyze the optical performance of the heliostat. The optical errors of the heliostat and the attenuation of reflected solar irradiance in the air have not been taken into account yet.

Two new methods used to simulate the circumferential solar flux density concentrated on the absorber of a parabolic trough solar collector

The optical efficiencies of a solar trough concentrator are important to the whole thermal performance of the solar collector, and the outer surface of the tube absorber is a key interface of energy flux. So it is necessary to simulate and analyze the concentrated solar flux density distributions on the tube absorber of a parabolic trough solar collector for various sun beam incident angles, with main optical errors considered. Since the solar trough concentrators are linear focusing, it is much of interest to investigate the solar flux density distribution on the cross-section profile of the tube absorber, rather than the flux density distribution along the focal line direction. Although a few integral approaches based on the “solar cone” concept were developed to compute the concentrated flux density for some simple trough concentrator geometries, all those integral approaches needed special integration routines, meanwhile, the optical parameters and geometrical properties of collectors also couldn’t be...

The backward ray tracing with effective solar brightness used to simulate the concentrated flux map of a solar tower concentrator

The solar tower concentrator is mainly composed of the central receiver on the tower top and the heliostat field around the tower. The optical efficiencies of a solar tower concentrator are important to the whole thermal performance of the solar tower collector, and the aperture plane of a cavity receiver or the (inner or external) absorbing surface of any central receiver is a key interface of energy flux. So it is necessary to simulate and analyze the concentrated time-changing solar flux density distributions on the flat or curved receiving surface of the collector, with main optical errors considered. The transient concentrated solar flux on the receiving surface is the superimposition of the flux density distributions of all the normal working heliostats in the field. In this paper, we will mainly introduce a new backward ray tracing (BRT) method combined with the lumped effective solar cone, to simulate the flux density map on the receiving-surface. For BRT, bundles of rays are launched at the recei...