Find the internal energy and entropy , Chemical Engineering

1 ΔS on rapid decompression

Steam at 400C, 100 bar in an insulated cylinder is suddenly decompressed to 10 bar, by unlocking the piston and allowing the gas to expand, with a constant external pressure of 10 bar applied to the piston. Find the final temperature T2, and the entropy change ΔS.

To answer the problem, ask yourself the following questions:

1) How much work is done as the steam expands?

2) What does energy conservation tell you in this situation?

2 Reversible heating with reservoirs

a)  A system with constant heat capacity CP and initial temperature T1 is heated by contacting a reservoir at Tf . Find the entropy change of the system, reservoir, and system plus reservoir. Evaluate the total entropy change assuming Tf = 2T1.

b) The same system is now heated in two stages, by first contacting with a reservoir at T2 halfway between T1 and Tf , then by contacting with the reservoir at Tf . Again find the entropy change of system, reservoirs, and system plus reservoirs, and again evaluate the total entropy change.

c)  The system is now heated in n stages, by contacting with reservoirs at n equally spaced

Ti between T1 and Tf . Write an expression for the entropy change of the system, reservoirs, and system plus reservoirs. How does this compare to the limit of reversible heating as n becomes large?

3 Carnot cycle in steam

Consider a Carnot heat engine operating with steam as the working uid, between reservoirs at

TL = 200C and TH = 500C.

Do the following, using the steam tables:

1) Sketch the cycle on a PV diagram. Label the state points 1, 2, 3, 4 starting with the low-pressure, low-temperature state.

2)  Let the lowest pressure in the cycle (P1) be 1 bar, and the highest (P3) be 80 bar. Find the values of P2 and P4.

3)  Compute the heat Q and work W on each leg of the cycle; tabulate your results (SI units).

4)  Compute the efficiency of this cycle as a heat engine. Compare to the ideal-gas result for the Carnot efficiency, and briey comment on the comparison.

4 van der Waals U, S

For a substance described by the van der Waals equation of state with a constant heat capacity CV :

1) Find the internal energy U(T; V ), relative to a reference state at some T0; V0.

2) Find the entropy S(T; V ), likewise.

Posted Date: 2/20/2013 5:20:18 AM | Location : United States







Related Discussions:- Find the internal energy and entropy , Assignment Help, Ask Question on Find the internal energy and entropy , Get Answer, Expert's Help, Find the internal energy and entropy Discussions

Write discussion on Find the internal energy and entropy
Your posts are moderated
Related Questions
Find the Composition of Product Gas Methane reacts with 100 % excess oxygen to form formaldehyde and water. However, in an undesired side reaction, some of the methane is comb

Dear expert minds I have to program in Matlab a series of Unit operations for protein purification fro crude mixture. Starting from the centrifugation arriving to the formulation o

Electric susceptibility The electric susceptibility χ e of a dielectric material is a calculate of how easily it polarizes in response to an electric field. This, in turn, ver

edta softeninig numerical problems

chemistry separate the mixture of sand and naphthalene by sublimation

If the atmosphere had a constant temperature of 20C and constant density, how high would the air extend above sea level? Would Mt. Everest, and 10km in elevation, protrude beyond

What are the objectives of heat treatment processes? The heat treatment is generally adopted for the following: (i)  To refine grain structure (ii) For better machinabili


chemistry separate the mixture of sand and naphthalene by sublimation

Process Description For Production of Chemicals from Coal Before it can be fed to the gasification reactor, coal must be ground to meet specifications on particle size. The gr