Question

9.98 kg of R-134a at 300 kPa fills a rigid container whose volume is 14 L. Determine the temperature and total enthalpy in the container. The container is now heated until the pressure is 600 kPa. Determine the temperature and total enthalpy when the heating is completed. Use data from the steam tables.

Answer 1

Before heating

Temperature = 133.5 °C

Total enthalpy = 27,195.5 kJ

After heating

Temperature = 158.8 °C

Total enthalpy = 27,514.86 kJ

Step-by-step explanation:

Before heating

Pressure = 300 kPa = 300/100 = 3 bar

From steam tables,

At 3 bar, temperature is 133.5 °C and specific enthalpy is 2725 kJ/kg

Total enthalpy = specific enthalpy × mass = 2725 × 9.98 = 27,195.5 kJ

After heating

Pressure = 600 kPa = 600/100 = 6 bar

From steam tables,

At 6 bar, temperature is 158.8 °C and specific enthalpy is 2757 kJ/kg

Total enthalpy = specific enthalpy × mass = 2757 × 9.98 = 27,514.86 kJ