Experiments on a discretized 3D compound parabolic concentrator with a sensible heat storage

• Published in: Next Energy 2025-04, Vol.7, p.100224, Article 100224
• Main Authors: Lwiwa, Casiana Blasius, Nydal, Ole Jørgen
• Format: Article
• Language: English
• Subjects: Compound parabolic concentrator; Concentrating solar for cooking; Heat storage for cooking; Solar heat storage; Solar thermal
• ISSN: 2949-821X; 2949-821X
• DOI: 10.1016/j.nxener.2024.100224

A Compound Parabolic Concentrator (CPC) is investigated for capturing and focusing sun rays onto an absorber, for conversion of solar radiation to heat. CPCs are cost-effective as they do not need solar tracking, only requiring tilting of the concentrator at intermediate times during a day. In this study, a 3D CPC with reflecting surfaces is strongly simplified by using only two sets of 4 flat mirrors (upper and lower mirrors) arranged in such a way that they form a quadratic funnel. A cylindrical heat absorber made of aluminum is positioned at the base of the funnel and the system is insulated to reduce the heat losses from the system. The purpose of the heat storage is to accumulate heat at sufficient temperatures for cooking. The idea is that a concentrator can be positioned over the heat storage and be replaced by an insulating cover after the heat storage has been charged. Tests with a CPC system is presented here, with test results in outdoor conditions in Trondheim, Norway during the months of May and June. The heat storage reached temperatures of about 135 °C at solar radiation conditions of 500–700 W/m2, higher temperatures are to be expected with improved insulation and at sun conditions closer to equator. Previous separate cooking tests have been successfully demonstrated on a similar cylinder for initial heat storage temperatures of 220 °C. A computational model which was tuned to the 220 °C case showed that even an initial temperature of 140 °C can be sufficient for boiling water although at modest amounts of about 1 l. •An aluminum cylinder placed in a simplified 3D CPC was heated in outdoor conditions.•The purpose of the tests was to identify whether suitable temperatures for cooking can be achieved on the heat storage.•The absorber temperatures reached a maximum of 135 degrees C on the day with highest average solar radiation.•Some computational illustrations showed that even modest storage temperatures can provide sufficient cooking power.•Similar test at good sun conditions closer to equator is expected to show higher temperatures, suitable for cooking.