Thermodynamics Problems

THERMODYNAMICS ASSIGNMENT

1.

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If during an experimentation process the volume of gas changes from 5 to 15 ft and the pressure changes according to the 3

equation P = 1000(0.30V + 1), what is the work done in ft- lb by the gas? Pressure are express in psia and ft . 2.

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Steam at 1000 lb f /ft  pressure and 300R has a specific enthalpy of 9800 lb f  – ft/lbm. Find the internal energy in ft  – lb f /lbm of the steam.

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During a non-flow process, the internal energy of a fluid changes from an initial value of 500 Btu/lb to a final value of 440 Btu/lb. if 3000 ft/lb added to or removed from the fluid during the process.

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A non-flow (closed) system contains 1 pound of an ideal gas (Cp = 0.24, Cv = 0.17). The gas temperature is increased by 10 F while Btu of work are done by the gas. What is the heat transfer in Btu?

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(ISOBARIC PROCESS) Calculate the heat required in Btu to raise the temperature of 1 lbmol of methane from 500 to 1000 F 3

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in a flow process in a constant pressure of 12 atm, Cp = 3.381 + 18.044 x 10 T – 4.3000 x 10 T . Where T in K and Cp in o

Btu/mol F. 6.

Gas is enclosed cylinder with a weigh piston as the top boundary. The gas is heated and expands from a volume of 0.60m

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at constant pressure of 250 KPa. What is the work done by the system? 7.

Calculate the ∆H in Btu for 1 lb m of water when it is

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vaporized at the constant temperature of 212 F and the constant 3

pressure of 1 atm. The specific volumes of liquid and water vapor at these conditions are 0.0167 and 26.80 ft /lbm, respectively. For this change, 970.3 Btu is added to water as heat. 8.

A 2.53 KJ of heat is absorbed by an ideal gas that occupies a volume 22.4L at STP. If the gas expands isobarically to 32.4 liters. Compute the change of internal energy of the gas.

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Two Kg of air is heated at constant pressure of 200 KPa to 500 C. Calculate the entropy change if the initial volume is 0.8m . o

10. Ten lb of water at 14.7 psia is heated at the constant pressure from 40 F to saturated vapor. Compute the entropy change. o

11. (ISOMETRIC PROCESS) Find the change in internal energy of 5 lb m oxygen gas when the temperature changes from 100 F to o

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120 F, Cv = 0.157 Btu/lb m – R. o

12. What is the change in enthalpy per lb m of nitrogen gas its temperature is reduced from 500 F at a constant pressure (Cp = o

0.23483 Btu/lbm- R). 13. Air is at 1 bar and 298.15 K is compressed to 5 bars and 298.15 K by cooling at constant pressure followed by heating at constant volume. Calculate the change of enthalpy for the entire process in J/mol. 14. (ISOTHERMAL PROCESS) Two pound of air is compressed from a 20 psia to 200 psia while maintaining the temperature o

constant at 100 F. Calculate the heat transfer needed to accomplish this process. 3

15. What horsepower is required to isothermally compress 800 ft  of air per minute from 14.7 psia to 120 psia? o

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16. Ninety kilograms of ice at 0 C are completely melted. Find the entropy change, in KJ/K if T 2 = 0 C. 17. Calculate the entropy change for hundredfold expansion of a mole of ideal gas isothermally. 18. A rigid tank contains a hot fluid that is cooled while being stirred by a paddle wheel. The internal energy of energy of fluid is 800 KJ and loses 500 KJ of heat during cooling process with the paddle work of 100 KJ applied in the fluid. Neglecting the energy stored in paddle wheel, determine the final internal energy of the fluid. o

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19. Calculate the entropy change in cal/ K if 350 grams of water at 5 C is mixed with 500 grams of water at 70 C.