An energy thrifty solar cooler—The mina oven

A commercial version of the Telkes oven was modified to feature a vapor-tight pot that was thermally bonded to a single glazed collector plate. The resulting spillproof Mina ovens of 0·18 m2 aperture area were tested along with a similarly sized sunspot oven in heating water and oil, and in cooking. For Mina ovens a cooking time for meat dishes of about 70 min was recorded for a charge of 400g of meat and rice. The characteristic water boiling time of about 24 min·m2 kg−1 was achieved by the Mina ovens which was a fraction of that of the Telkes oven. Various criteria were proposed for the assessment of performance of cookers. The overall utilization efficiency as well as the characteristic boiling time were observed to be particularly useful. The developed Mina ovens with an overall utilization efficiency up to 27% ranked the best in performance among other cookers in the literature.