A closed metal cylinder contains steam at 1 bar and 500 C. how much heat must be removed at constant
volume in order to produce saturated vapor.
Saturated vapor is steam that has not been heated past the boiling point for that pressure.
saturated vapor has a "quality" of 100% and happens at 100oC and 1 atm.,
therefore the temperature change will be 500oC – 100oC = 400
Heat transfer = (mass)(specific heat)(temperature change)
Q = mcΔT
Q = heat that need to be removed
m = mass; since the volume remains constant, the mass of the vapor will remain constant (1)
c = specific heat, J/g °C, from the steam table = 2.0373
ΔT = change in temperature
= 1x 2.0373 x 400 = 814.92 J
Liquid water at 180 C and 1002 kPa has internal energy of 762.0 kJ kg and a specific volume of 1.128
What is its enthalpy?
𝐻=𝑈+𝑃𝑉=762.0 kJkg+(1002.7 kPa)(1.128 cm3g)(1 m100 cm)3(1000 g1 kg)=𝟕𝟔𝟑.𝟏 𝐤𝐉𝐤𝐠
b) The water is brought to the vapor state at 300 °C and 1500 kPa, where its internal energy is
2784.4 kJ/kg and its specific volume is 169.7 cm3/g. Calculate ΔU and ΔH for the process.
Δ𝑈=2784.4 kJkg−762.0kJkg=𝟐𝟎𝟐𝟐.𝟒 𝐤𝐉𝐤𝐠
𝐻2=𝑈2+𝑃2𝑉2=2784.4 kJkg+(1500 kPa)(169.7 cm3g)(1 m100 cm)3(1000 g1 kg)=𝟑𝟎𝟑𝟖.𝟗𝟓 𝐤𝐉𝐤𝐠
Δ𝐻=3038.95 kJkg − 763.1 kJkg= 𝟐𝟐𝟕𝟓.𝟗 𝐤𝐉/𝐤𝐠
0.2 of air initially at 0.6 bar and 20 C undergoes the cycle consisting of three mechanically reversible
process. The air is compressed isothermally to a pressure of one bar during the process 1-2.
A heat engine produces energy by taking in 100 Kj/mol of heat from a reservoir at 600K and exhausts
heat to the environment at 300K. What is the maximum work that can be achieved by this engine and the
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