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<?xml version="1.0" encoding="iso-8859-1"?>
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<meta http-equiv="content-type" content="text/html; charset=iso-8859-1" />
<title>ReadingGuide_Thermo_Ch4_Solution</title>
<meta name="generator" content="Amaya, see http://www.w3.org/Amaya/" />
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<body>
<p><strong>Chapter 4 The Second Law of Thermodynamics:</strong></p>
<p></p>
<p><br />
<p><strong>Introduction:</strong></p>
<br />
<p>-What limits the use of energy within a source? <span id="ans">Second law of
thermodynamics.</span></p>
<p>-Can heat be transferred from cold to hot body arbitrarily? <span
id="ans">No, Work must be done.</span></p>
<p></p>
<br />
<p><strong>4.1 Reversible and Irreversible Processes:</strong></p>
<br />
<p>-What is reversible process? <span id="ans">The system and environment can
be restored to exactly the same initial states that they were in before the
process occured.</span></p>
<p>-What is the necessary condition for reversible process? <span
id="ans">should be Quasi-static.</span></p>
<p>-What is irreversible process? <span id="ans">The system and environment
cannot be restored to their original states.</span></p>
<p>-What is Clusius statement for second law of thermodynamics? <span
id="ans">Heat never flows spontaneously from a colder object to a hotter
object.</span></p>
<p>-Table 4.1: Look at Summary common reversible processes.</p>
<p></p>
<br />
<p><strong>4.2 Heat Engines:</strong></p>
<br />
<p>-What is heat engine? <span id="ans">A device used to extract heat from a
source and then convert it into mechanical work.</span></p>
<p>-What is the expression for work done for a cycle of heat engine in terms of
heats exchanged? <span id="ans">Eqn. (4.1)</span></p>
<p>-What is the expression for the efficency of heat engine? <span
id="ans">Eqn. (4.2)</span></p>
<p></p>
<br />
<p><strong>4.3 Refrigerators and Heat Pumps:</strong></p>
<br />
<p>-What is the purpose of refrigerator engine? <span id="ans">to remove heat
from cold reservoir.</span></p>
<p>-What is the expression for the coefficient of performance of a
refrigerator? <span id="ans">Eqn. (4.3)</span></p>
<p>-What is the effectiveness or coefficient of performance of heat pump? <span
id="ans">Eqn.(4.4)</span></p>
<p></p>
<p><strong>4.4 Statements of the Second Law of Thermodynamics:</strong></p>
<p>-What is the Kelvin statement for second law of thermodynamics? <span
id="ans">It is impossible to convert the heat from a single source into work
without any other effect.</span></p>
<p>- "If the Clausius statement is false, the Kelvin statement must alos be
false." Look how this statement is explained in Fig. (4.9)</p>
<p>-What are two important porperties of the heat engines? <span id="ans">1)
Any reversible engine has greater efficiency than irreversible engine under
same condition. 2) All reversible engines have same efficency under same
conditions.</span></p>
<p></p>
<br />
<p><strong>4.5 The Carnot Cycle:</strong></p>
<br />
<p>-What is carnot cycle?<span id="ans">Hypothetical working cycle with highest
possible efficency.</span></p>
<p>-What are the steps of the carnot cycle? <span id="ans">1)Isothermal
expansion 2) Adiabatic expansion 3) Isothermal compression 4)Adiabatic
compression</span></p>
<p>-What is the expression for the efficiency of ideal gas carnot engine?<span
id="ans">Eqn. (4.5)</span></p>
<p>-Do all reversible cycles operating between the same two reservoirs have
same efficiency? <span id="ans">Yes.</span></p>
<p>-Fig. (4.13): Look how the steps of the carnot cycles are represented in PV
diagram.</p>
<p>-What is the expression for the performance of the ideal-gas carnot
refrigirator? <span id="ans">Eqn. (4.6)</span></p>
<p>-What is the coefficient of performance for a Carnot heat pump?<span
id="ans">Eqn. (4.7)</span></p>
<p>-What is the Carnot's principle? <span id="ans">No engine working between
two reservoirs at constant temperatures can have a greater efficiency than a
reversible engine.</span></p>
<p></p>
<p></p>
<br />
<p><strong>4.6 Entropy: </strong></p>
<br />
<p>-Is change in entropy a path independent?<span id="ans">Yes. It is a state
function.</span></p>
<p>-What is the expression for the change in entropy for a reversible process
at a constant temperature? <span id="ans">Equation (4.8)</span></p>
<p><span id="prob">-Error: Last line of the 161 page of pdf. The expression
ΔS<sub>i</sub>=Q<sub>i</sub>/T<sub>i</sub> should be replaced by
ΔS<sub>i</sub>=ΔQ<sub>i</sub>/T<sub>i</sub>.</span></p>
<p>-What is the expression for the change in entropy of a system for an
arbitrary, reversible transition for which temperature is not necessarly
constant? <span id="ans">Eqn. (4.10)</span></p>
<p>-What is the net change in entropy of a system undergoing any complete
reversible cycle? <span id="ans">Zero.</span></p>
<p>-How the entropy of closed system or the entire universe change? <span
id="ans">It is always grater or equal to zero.</span></p>
<p>-What is the entropy statement for the second law of thermodynamics? <span
id="ans">The entropy of a closed system and entire universe never
decreases.</span></p>
<p>-Example (4.5): Look how the entropy change for an isobaric process is
obtained with the help of equation (4.10).</p>
<p>-Example (4.6): Look how the PV diagram for steps of the stirling engine is
drawn and how the work done, heat exhanged and change in entropy are calculated
for each steps.</p>
<p></p>
<br />
<p><strong>4.7: Entropy on a Microscopic Scale:</strong></p>
<br />
<p>-What measures the randomness of system? <span id="ans">Entropy.</span></p>
<p>-What happens to entropy of closed system for irreversible process? <span
id="ans">Always increases. Eqn. (4.12)</span></p>
<p>-What is third law of thermodynamics? <span id="ans">The absolute zero
temperature cannot be reached through any finite number of cooling
steps.</span></p>
<p>-What happens when a system's temperature approaches to absolute zero? <span
id="ans">The system becomes perfectly ordered and its entropy approaches to
zero.</span></p>
<p>-Example 4.9: Look how the first law of thermodynamics is used to find the
change in entropy for the adiabatic free expansion.</p>
<p></p>
</p>
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