Performance comparison of two solar cooking storage pots combined with wonderbag slow cookers for off-sunshine cooking

Two similar storage cooking pots are experimentally evaluated and compared during solar cooking and storage off-sunshine cooking periods. One storage pot has sunflower oil as the sensible heat storage material, while the other has erythritol as the phase change material (PCM). To test their thermal performance during off-sunshine periods, the two pots are placed in insulated wonderbag slow cookers. Water and sunflower oil are used as the cooking fluids in the experimental tests. The sunflower oil cooking pot shows better performance during the solar cooking periods since it shows shorter cooking times (1.8–5.6 h) compared to the erythritol PCM pot (3.8–6.6 h). The sunflower oil pot also attains higher maximum storage temperatures (124–145 °C) compared to the erythritol PCM pot (118–140 °C). Storage efficiencies for the sunflower oil pot (3.0–7.1%) are also greater than those of the PCM pot (2.5–3.7%). During the storage cooking periods, the erythritol based phase change material cooking pot shows better performance as evidenced by the lower temperature drops (0.1–9.7 °C) from the maximum cooking temperatures compared to 8.3 to 34 °C for the sunflower oil pot. The heat utilisation efficiencies for the erythritol pot (4.8–14.3%) are also greater compared to the sunflower oil pot (3.7–6%)