Question

A solar cooker and a pressure cooker both are used to cook food. Treating them as thermodynamic systems, discuss the similarities and differences between them.

Answer 1

Similarities:-

1. Both solar and pressure cookers involve thermodynamic systems which are closed. Here they allow the transfer of heat energy through the system boundaries but not matter. Hence, they are both mechanically isolated.
2. In both systems, the thermodynamic process is often isochoric. Both systems involve a chamber which retains heat while limiting the transfer of all matter including air. The process is hence contained in a constant volume as the pressure and temperature increases. The application of this phenomenon is that food gets cooked at higher temperatures.
3. In the thermodynamic systems of both types of cookers, heat is supplied to the system and the heat is directly converted to internal energy and work done is zero.

Differences:-

1. The pressure cooker receives its energy directly from a flame or another heat source, such as a stove. A solar cooker makes use of the thermal energy that is produced when sunlight is absorbed.
2. In comparison to a solar cooker, the pressure in a pressure cooker is relatively quite high. The temperature inside a pressure cooker is substantially higher because, according to the laws of gases, the pressure is exactly proportional to the temperature. The temperature rise in the solar cooker is gradual since heat is retained inside the apparatus.
3. Due to the higher temperatures involved in a pressure cooker than a solar cooker, the method of cooking in a pressure cooker is exceptionally quick.