Solar cookers can be used in less developed countries for cooking and also for thermal disinfection of water. To disinfect water, the water must be heated to about 35 Celsius for 5 hours. Of course, it takes time to raise the temperature of the water up to 35 Celcius. A hemispherical hole 2.75 m in diameter is dug into the ground, lined, and filled with water (no inflow or outflow of water) for heating. Assume the tray is insulated by soil so that no heat escapes. The solar intensity is 4,500 W/m2
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A. Write the energy balance for this system in words.
B. What hydrodynamic model would you use for this system (batch, CSTR, or plug flow) and why?
C. If the water is heated for time t (in seconds), what is the value of the "energy in" term in joules?
D. How long will it take to raise the water temperature from 20 Celcius to 35 Celcius? Use the model you have been developing in Parts A, B, and C.