Question

A 8 ft rigid, sealed tank contains ammonia (NH3) at its critical temperature and pressure. Calculate the mass of the ammonia in the tank by three methods:

a. by using the Thermodynamic Properties of Ammonia Table.
b. by assuming that the ammonia is an ideal gas, and
c. by using the Compressibility Factor Equation of State. What is the compressibility factor Z?
d. Of these three answers for the mass, which is the most accurate? Which is the least accurate?
e. Now the ammonia in the tank is cooled to a final temperature of 14°
F. Using the Thermodynamic Properties of Ammonia Table, determine the final pressure and quality of the ammonia.
f. Calculate the required heat transfer for part e

Answer 1

To calculate the mass of ammonia in the tank, three methods can be used: Thermodynamic Properties of Ammonia Table, assuming ideal gas behavior, and using the Compressibility Factor Equation of State. The most accurate method is by using the Thermodynamic Properties of Ammonia Table, while assuming ideal gas behavior is the least accurate method. After cooling the ammonia, the final pressure and quality can be determined using the Thermodynamic Properties of Ammonia Table.

Step-by-step explanation:

The mass of the ammonia in the tank can be calculated using three methods: by using the Thermodynamic Properties of Ammonia Table, by assuming that the ammonia is an ideal gas, and by using the Compressibility Factor Equation of State.

To calculate the mass by using the Thermodynamic Properties of Ammonia Table, find the saturation temperature and pressure values and use the specific volume value to determine the mass.

To calculate the mass by assuming that the ammonia is an ideal gas, use the ideal gas law equation: PV = nRT. Rearrange the equation to solve for n, the number of moles, and then multiply by the molar mass of ammonia to get the mass.

To calculate the mass by using the Compressibility Factor Equation of State, determine the compressibility factor Z using the equation PV = ZnRT, rearrange the equation to solve for n, and then multiply by the molar mass of ammonia to get the mass.

The most accurate method for calculating the mass of ammonia in the tank is by using the Thermodynamic Properties of Ammonia Table, as it takes into account the specific properties of ammonia at its critical temperature and pressure. The least accurate method is by assuming that the ammonia is an ideal gas, as this method does not account for any deviations from ideal gas behavior.

To determine the final pressure and quality of the ammonia after it is cooled to a final temperature of 14°F, refer to the Thermodynamic Properties of Ammonia Table and find the values for saturation temperature and pressure at 14°F. Use these values along with the specific volume value to determine the final pressure and quality of the ammonia.

To calculate the required heat transfer, use the equation Q = m × ΔH, where Q is the heat transfer, m is the mass of ammonia, and ΔH is the heat of vaporization.