CCB 2024 Chemical engineering thermodynamics
September 2013
Tutorial No. 1 (Lecture 1-3) Questions
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1.
A mass of 1.2 kg of air at 150 kPa and 12 C is contained in a gas-tight, frictionless pistoncylinder device. device. The air is now compressed to a final pressure of 600 kPa. During the process, heat is transferred from the air such that the temperature inside the cylinder remains constant. Calculate the work done done during this process. Given, Given, the gas constant of air is 0.287 kJ/kg. K.
2.
one mole of an ideal gas with C p=(7/2)R and C v v=(5/2) R expand from P 1=8 bar and T 1=600K to P2=1 bar by each of the flowing paths: (a)Constant volume (b) Constant temperature (c) Adiabatically Assuming mechanical reversibility, calculate W, Q, ΔU, and ΔH for each process. Sketch each on a single PV diagram. (Problem 3-8, Smith et al. 2005)
3.
An ideal gas initially at 600 K and and 10 bar undergoes a four-step mechanically mechanically reversible cycle in a closed system .in step 12, pressure decreases isothermally to 3 bar, in step 23, pressure decreases at constant volume to 2 bar,in step 34, volume decreases at constant pressure; and in step 41 ,the gas returns adiabatically to the initial state. Take Cp=(7/2)R and Cv=(5/2)R (a) Sketch the cycle in PV diagram. (b)
Determine (where unknown) both T and P or state 1, 2, 3, and 4.
(c)
Calculate W, Q, ΔU, and ΔH for each step of the cycle. (Problem 3-9, Smith et al. 2005 )
4.
An ideal gas, Cp=(5/2)R and Cv=(3/2)R, is changed from P=1 bar and V 1t=12 m3 to P 2 =12 t 3 and V2 =1 m by the following mechanically reversible process: (a) Isothermal compression (b)
Adiabatic compression followed by cooling at constant volume.
(c)
Heating at constant volume followed by cooling at constant pressure
(d)
Cooling at constant pressure followed by heating at constant volume t
Calculate Q, W, ΔU and ΔH for each of these processes and sketch the paths of all processes on a single PV diagram. 5.
(Problem 3-10, Smith et al. 2005 )
one cubic meter of an ideal gas at 600 K and 1000 KPa expend to five times its its initial initial volume as follows: (a) By a mechanically reversible, isothermal process (b)
By a mechanically reversible, adiabatic adiabatic process
(c)
By an adiabatic, irreversible process in which expansion is against a restraining r estraining pressure of 100KPa
1
CCB 2024 Chemical engineering thermodynamics
September 2013
For each case calculate the final temperature, pressure and the work done by the gas. C p=21 -1 -1 Jmol K . (Problem 3-19, Smith et al. 2005)
6.
one mole o an ideal gas, initially at 30°c temperature (303.15 K) and 1 bar, is changed to 130°c(403.15 K) and 10 bar by three different mechanically reversible processes: The gas is first heated at constant volume until its temperature is 130°c; then it is
compressed isothermally until its pressure 10 bar
The gas is first heated at constant pressure until its temperature is 130°c; then it is compressed isothermally to 10 bar
The gas is first compressed isothermally to 10 bar; then it is heated at constant pressure to 130°c
Calculate W, Q, ΔU, and ΔH for each case, of the cycle. Take C p=(7/2)R and Cv=(5/2)R. alternatively, take C p=(5/2)R and Cv=(3/2)R. ((Problem 3-22, Smith et al. 2005) 3
7.
Nitrogen at 150 K has a specific volume of 0.041884 m /kg. Determine the pressure of nitrogen, using (a) The ideal gas equation and (b) The Beattie-Bridgeman equation. Compare your results to the experimental value of 1000 kPa. (Problem 3-97, Cengel et al)
8.
Determine the pressure of water vapor at 350 °C and 0.035262 m3/kg, using (a) The ideal gas equation, and (b) The generalized compressibility chart Which method is suitable if the experimental value of is 7.0 MPa? Justify?
9.
Reported values for the virial coefficients of isopropanol vapor at 200 (473.15 K) are:
Calculate V and Z for isopropanol vapor at 200 (473.15 K) and 10 bar by (a) The ideal-gas equation (b) Truncated virial equation (2 terms) (c) Truncated virial equation (3 terms)
Formulae:
1+
( ters) 1 + + ( ters) 2
