Question

A 140litre container is to be used to store heat for a domestic heating system. There are two options for the storage material, lead blocks or clay bricks. Using the data provided determine which is the best option for the system.                                                         

Lead: specific heat 130J/kgK, density 11340kg/m³

Brick: specific heat 840kJ/kgK, density 2000kg/m³

2. A container holds 0.25m³ of compressed air at 900kPa and 20°C. This is expanded polytropically via a process with n=1.3 to a pressure of 150kPa. Determine;         

(2 marks each)

1. The mass of air
2. The final air temperature
3. The work transfer, stating if it is input or output work
4. The change in internal energy
5. The heat transfer , stating if this is heat input or output

please answer both the questions/

Answer 1