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material (one sensible heat storage material and one latent heat storage material) in a
solar cooker based on a Scheffler reflector for late evening or night cooking. Also, carry
out thermal analysis, water activity tests, rice taste surveys, and economic analysis of the
system. The experimentation was conducted at a specific location in Mehsana (23.5880°
N, 72.3693° E) in Gujarat, India.

After the experiment, food has been cooked in experiments with sand-iron pieces,
pebbles-sand, sand-pebbles, sand-acetamide, acetamide-sand, acetamide-pebbles, sand-
stearic acid, stearic acid-sand, and stearic acid-pebbles.

Out of six pairs of sensible heat storage materials as inner and outer materials, food has
been partially cooked in pairs of iron pieces-sand, iron pieces-pebbles, and pebbles-iron
pieces. In pairs of latent heat storage materials as inner and outer materials, both the
combination pair has been seen as partially cooked food. Combination pair of latent heat
storage and sensible heat storage materials cases, food has been partially cooked in
cases of pebbles-acetamide, iron pieces-acetamide, acetamide-iron pieces, pebbles-
stearic acid, iron pieces-stearic acid, and stearic acid-iron pieces.

The reason for partially cooked food was that the air gap between the gritted particles
acted as an insulator for heat transfer. The inner material assists in cooking, while the
outer material acts as an insulator and compensates for the heat loss from the inner
material.

Experimentally, it shows that food has been cooked when the temperature of the food in
the cooking pot is 60 °C or above at 20:00 hr; if it is less than 60 °C, it has been partially
cooked.

The water activity test is to be conducted to check the cooking of food quality at
Mansinhbhai Institute of Dairy & Food Technology, Dudhsagar Dairy, Mehsana, Gujarat,
India. As per the result received of test, the range of cooking and partially cooking is
differentiated between 0.928 to 0.937 and. 0.948 to 0.957 respectively.
Thermal analysis has been carried out for the present experimentation, and it has been
achieved in the range of 30 to 37%. For the calculation of payback period and levelized
cost of one meal, economic analysis is carried out. Economic analysis shows the total
expenditure, payback period, and levelized cost of one meal of the system were 52350
INR, 10.09 years, and 1.15 INR, respectively. The rice taste survey has been carried out to
check the food quality, and as per the feedback received on taste, colour, taste, smell,
texture, and overall acceptability, it was satisfactory.

Key words: Scheffler reflector, Solar energy, Solar cooker, Sensible heat storage materials,
Phase change materials, Combined heat storage materials, Late evening or night cooking

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