Example Problem - Property Lookups (3) скачать в хорошем качестве

Example Problem - Property Lookups (3)

A piston-cylinder arrangement contains steam and an electric-resistance heater. The cylinder is perfectly insulated to ensure minimal heat transfer with its surroundings, and rests on a table in a large room where the ambient conditions are 20°C and 1 bar. The steam in the cylinder is initially at 200°C and 150 kPa and occupies a volume of 0.25 m^3. Now, you plug the heater into a 120 V wall outlet, and measure the current running through the heater to be 5 A. The heater heats up the steam, causing the steam to isobarically expand. You stop the heater once the gas has expanded to 0.5 m^3. Complete the following: Determine the mass of the steam at the beginning of the heating process (kg) Determine the temperature of the steam at the end of the heating process (°C) Determine the time required for this process to occur (s)