Question

Question 1 [25 marks] a. A refrigerator absorbs heat from a space at 2°C and rejects heat to the outside air at 25°C. If the COP of the refrigerator is 16, is this refrigerator realistic? Justify your answer. b. Starting from the general form of the first law of thermodynamics, derive the final form of the law for a throttling valve which loses heat to the surroundings. State all your assumptions c. Using the generalized compressibility chart, what is the compressibility factor for water whose pressure and temperature are 2.2 MPa and 500°C, respectively? Can the water in this case be considered an ideal gas? Why? d. Define the latent heat of vaporization? How much is the latent heat of vaporization of water at 300 kPa? e. Consider a system which contains saturated liquid-vapor mixture of water at 160°C. The system is located in a place where the local atmospheric pressure is 102 kPa. What is the absolute (actual) pressure inside this system? If we want to express the pressure of the system as gage pressure or vacuum pressure, determine which one is more suitable for this case and calculate it.

          Question 1 [25 marks]
a. A refrigerator absorbs heat from a space at 2°C and rejects heat to the outside air at 25°C. If the
COP of the refrigerator is 16, is this refrigerator realistic? Justify your answer.
b. Starting from the general form of the first law of thermodynamics, derive the final form of the law
for a throttling valve which loses heat to the surroundings. State all your assumptions
c. Using the generalized compressibility chart, what is the compressibility factor for water whose
pressure and temperature are 2.2 MPa and 500°C, respectively? Can the water in this case be
considered an ideal gas? Why?
d. Define the latent heat of vaporization? How much is the latent heat of vaporization of water at
300 kPa?
e. Consider a system which contains saturated liquid-vapor mixture of water at 160°C. The system
is located in a place where the local atmospheric pressure is 102 kPa. What is the absolute (actual)
pressure inside this system? If we want to express the pressure of the system as gage pressure or
vacuum pressure, determine which one is more suitable for this case and calculate it.

Question 1 [25 marks]
a. A refrigerator absorbs heat from a space at 2°C and rejects heat to the outside air at 25°C. If the
COP of the refrigerator is 16, is this refrigerator realistic? Justify your answer.
b. Starting from the general form of the first law of thermodynamics, derive the final form of the law
for a throttling valve which loses heat to the surroundings. State all your assumptions
c. Using the generalized compressibility chart, what is the compressibility factor for water whose
pressure and temperature are 2.2 MPa and 500°C, respectively? Can the water in this case be
considered an ideal gas? Why?
d. Define the latent heat of vaporization? How much is the latent heat of vaporization of water at
300 kPa?
e. Consider a system which contains saturated liquid-vapor mixture of water at 160°C. The system
is located in a place where the local atmospheric pressure is 102 kPa. What is the absolute (actual)
pressure inside this system? If we want to express the pressure of the system as gage pressure or
vacuum pressure, determine which one is more suitable for this case and calculate it.

Added by Dawn R.

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