Experimental thermal performance assessment of three receiver configurations for a parabolic‐dish solar collector

Abstract This study compared three receiver assemblies on the same 3.14 m 2 two‐axis‐tracked parabolic‐dish collector using water at 0.020 kg s −1 . Each receiver was tested during a separate three‐day outdoor campaign, providing 99 sequential 15‐min averages. Direct normal irradiance (DNI) was derived from simultaneous unshaded and shaded measurements on the sun‐normal plane. Mean water‐temperature rises were 14.26, 17.33 and 19.75 K, and reported mean useful thermal powers were 1193.63 ± 60.38, 1450.66 ± 60.94, and 1653.54 ± 61.47 W for the non‐cavity, cavity and conical spiral receivers, respectively. Corresponding gross aperture‐based thermal efficiencies were 64.93%, 75.92% and 84.01%, with conditional propagated bounds of ±7.28, ±8.23, and ± 8.96 percentage points. The bounds depend on assigned temperature, flow and DNI allowances; the retained derived DNI has a provisional 10% allowance. Final manufacturing STEP dimensions support supplementary mean‐wall, loss‐path, hydraulic and optical calculations. Illustrative mean hot‐side wall estimates are 85.15, 84.37, and 72.75°C. The calculations are conditional scenarios, not new measurements. The spiral has the highest reported central efficiency, but separate outdoor campaigns and confounded geometry, material and flow paths limit the comparison to the tested assemblies.