Cylindrical solar absorber cavity length to diameter ratio investigation

摘要

Recently, solar thermal rocket propulsion concepts have primarily focused on "windowless" absorber designs. This investigation experimentally explored the geometric aspect of the simple cylindrical solar thermal absorber cavity. The criticalparameter used for the evaluation was the length to diameter ratio, which was varied from 2 to 8 (a dimensionless value). Two materials (tungsten and alumina) were used for a total of 12 absorber-heating tests. Temperature profiles were generated usingthermocouples on the outside of the insulated absorber shell. The data generated was analyzed and a new geometry comparison parameter (ψ) developed. This unique parameter is useful to indicate a range of length to diameter ratios, which optimizes thesolar absorption and heat transfer process in a windowless, cylindrically shaped, solar thermal absorber. The optimal ratio range was concluded to exist for the cylinder shaped cavity in the range of 3 to 6 for the materials investigated.