Solar cookers with latent heat storage for intensive cooking application

摘要

Many developing countries use biomass as their primary energy supply. Unwise utilization of biomass affects the environment, health and safety of women and children in particular. In addition, it causes indoor air pollution, which is a reason to the deaths of millions. This paper demonstrates solar cooker with an integrated PCM thermal storage and heat transportation loop suitable for high temperature applications. The system is designed to particularly suite Injera baking application. Injera, a yeast-risen flat bread type is the most common staple food type served three to four times a day in Ethiopia. A similar food type is also eaten in, Eritrea, Somalia, Sudan and Yemen. The system storage has a capacity of about 250°C and retains the heat for about two days. The storage is coupled polar mounted concentrator with fixed receiver and steam heat transfer fluid. The steam circulates naturally between the evaporator and condenser in a closed loop. The study has demonstrated indirect charging, simultaneous charging-discharging and discharging of the stored heat. The frying pan is a custom-made aluminum plate casted by embedding a 10mm coiled stainless steel steam pipe as heating element. The pan is 500mm in diameter and 30mm thick, and the fins are 20mm in diameter and 140mm long. The fins are immersed into a 20kg PCM, which is coupled to a 1.8m diameter parabolic dish collector. The solar fryer demonstrates Injera baking for average family size on top of a heat storage charged by a solar energy. This baked Injera able to cover three to four days food consumption of the family.