Lesson 23 1. (10 pt) Write the equation for the thermal efficiency of a Carnot heat engine below: 1 L H 2. (10 pt) Can the thermal efficiency of an actual engine ever exceed that of an equivalent Carnot engine? Yes/no 3. (10 pt) Write the equation for the COP of Carnot refrigerator below: CO P r L H L 4. (10 pt) Write the equation for the COP of a Carnot heat pump below. COP hp H H L 5. (20pt) List the completely reversible processes of a Carnot cycle below: (A) Isothermal expansion (B) Adiabatic expansion (C) Isothermal compression (D) Adiabatic compression 6. (10 pt) Write the inequality of Clausius below: Q 0 7. (5 pt) he inequality of Clausius is consistent with the Kelvin-Planck statement of the Second Law. 8. (15 pt) Write the inequality of Clausius for an internally reversible cycle below. Q 0 9. he of an actual heat engine must be positive/zero/negative.
Lesson 25 1. (5 pt) he entropy of a phase-change substance is found using tables. 2. (5 pt) Specific entropy of phase-changers is found in the same manner as all the other specific properties. 3. (5 pt) If s f <= s <= s g, the substance is a saturated mixture. 4. (5 pt) If s > s g, the substance is a superheated vapor. 5. (5 pt) If s < sf, the substance is a subcooled liquid. 6. (20 pt) Sketch the -s state diagram for a phase-changing substance below. Include one isobar and one constant volume process line. 7. (10 pt) If the substance is a subcooled liquid, s is approximately s f at the same temperature. 8. (5 pt) Quality is used in the same way for specific entropy as for other specific properties. 9. (10 pt) Is it possible to convert a superheated vapor to a compressed liquid with a constant entropy process? Yes/No 10. (10 pt) Is it possible to convert a superheated vapor to a compressed liquid in an isothermal process? Yes/No 11. (10 pt) Is it possible to convert a superheated vapor to a compressed liquid in an isobaric process? Yes/No 12. (10 pt) Is it possible to convert a superheated vapor to a compressed liquid in a constant volume process? Yes/No
Lesson 26 1. (10 pt) A Mollier diagram is a h-s state diagram. 2. (10 pt) When a closed system consisting of a phase-changing substance undergoes an isobaric process such that the entropy increases, the temperature will always increase. rue/false 3. (10 pt) Ideal turbines and compressors execute constant entropy processes. 4. (10 pt) Ideal nozzles and diffusers execute constant entropy processes. 5. (10 pt) Entropy can only be transferred by heat, not work. 6. (10 pt) Heat is a form of disorganized energy while work is not. 7. (10 pt) During a constant volume process, like a rigid container, the ds equation reduces to: ds = du 8. (10 pt) During a constant pressure process, like flow through a pipe, the ds equation reduces to: ds = dh 9. (20 pt) During an isobaric phase change from a saturated liquid to a saturated vapor, the relationship between the enthalpy of vaporization and entropy of vaporization is: s fg = h fg /
Lesson 27 10. (10pt) Oil in an automobile engine is stirred by the action of the internal parts. If this is done with no heat transfer, you would expect the entropy of the oil to increase/decrease. 11. (10 pt) he Carnot cycle processes form a rectangle when drawn on a -s state diagram. 12. (10 pt) Constant entropy processes form a _Vertical line when drawn of a -s state diagram. 13. (10 pt) Areas below reversible processes on -s state diagrams represent transfer. 14. (10 pt) he heat transfer during a reversible, isobaric conversion of a saturated liquid to a saturated vapor is given by: s fg 15. (10 pt)he change in the entropy (in terms of the specific volume) of an ideal gas with constant specific heats as it undergoes an isothermal process is given by: s 2 -s 1 = Rln(v 2 /v 1 ) 16. (10 pt)he change in the entropy (in terms of the absolute temperature) of an ideal gas with constant specific heats as it undergoes an isobaric process is given by: s 2 -s 1 = c p ln( 2 / 1 ) 17. (10 pt)he change in the entropy (in terms of the pressure) of an ideal gas with variable specific heats as it undergoes an isothermal process is given by: s 2 -s 1 = -Rln(P 2 /P 1 ) 18. (10 pt)he change in the entropy (in terms of the absolute temperature) of an ideal gas with variable specific heats as it undergoes an isobaric process is given by: s 2 -s 1 = integral (c P d/) 19. he entropy change of an incompressible substance with constant specific heat is given by: s 2 -s 1 = cln( 2 / 1 )
Lesson 28 1. (10 pt) he entropy change of a system is always greater than of equal to Q /. 2. (5 pt) dq / can be considered as an entropy transfer with heat. 3. (5 pt) Entropy is produced by irreversible processes. 4. (5 pt) Entropy production is a property of a system. rue/false 5. (10 pt) he entropy of an isolated system must always increase or remain fixed. 6. (10 pt) Entropy production of a closed system equals the sum of the entropy change of the system and system heat transfers. 7. (10 pt) If S prod is negative, the process is impossible. 8. (10 pt) If S prod is positive, the process is irreversible. 9. (10 pt) he entropy production for the most effective process is zero. 10. (10 pt) Processes always proceed in directions in which the entropy production is positive or zero. 11. (10 pt) Entropy is not conserved, but is always being produced. 12. (5 pt) Entropy production is a measure of the irreversibility of a process.
Lesson 29 1. (15 pt) Write the general rate form of the entropy balance below. Q ds ms ms prd in out dt 2. (15 pt) Entropy is transferred into and out of a system by mass transfer and heat transfer but not by work transfer. 3. (10 pt) Write the equation for the rate of entropy transfer by heat below: q S da A 4. (10 pt) Write the equation for the total entropy change of a internally reversible, isothermal system below: S = Q/ 5. (10 pt) When there is no heat transfer between a system and its surroundings, the entropy production must be either zero or positive. 6. (10 pt) Write the equation for the entropy production for a closed system below: Q m ( s ) 0 2 s 1 prd 7. (10pt) Write the equation for the entropy production for a single-stream, steady-state system below: q s s 0 1 2 prd 8. (10 pt)he entropy of an isolated system must always increase or remain fixed. 9. (10 pt) Write the equation for the entropy production for a multi-stream, steady-state system below: Q ms ms 0 prd in out
Lesson 30 1. (15 pt) Write the general for the r3eversible work of a single stream, steady-state system below: w vdp ke pe 2. (15 pt) Rewrite the equation of Problem 1 for an incompressible substance with negligible ke and pe below: w v( P P ) 2 1 3. (10 pt) Write Bernoullis equation below: 2 2 V V 2 1 vdp g( z z ) 0 2 1 2 4. (15 pt) On P-v state diagrams, the area to the _left_ of a reversible process line represents work consumed by a single-stream, _steady-state_ system. 5. (10 pt) he larger the specific _volume_ in a flowing system, the larger the work transfer. 6. (10 pt) Reversible work production is always _greater than_ or _equal to_ the actual work production. 7. (5 pt) he reversible process that require the least reversible work consumed by a compressor is the _reversible_ process. 8. (15 pt) Write the equation for the reversible work production of a single-stream, steady-state device through which an ideal gas experiences a polytropic process in terms of the inlet and outlet temperatures below: Rn w ( ) 2 1 1 n 9. (5 pt) An isentropic process is a special case of a polytropic process where n = _k_.
Lesson 31 1. 2. 3. 4. 5. 6. (10 pt) An isentropic process is also a reversible and adiabatic process. (15 pt) An isentropic expansion process is one in which the pressure and temperature decrease while the entropy remains constant. (15 pt) An isentropic compression is one in which the pressure and temperature increase while the entropy remains constant. (10 pt) For an ideal gas with constant specific heats undergoing an isentropic process, the relationship between pressure and specific volume is given by: Pv k = constant (10 pt) For an ideal gas with constant specific heats undergoing an isentropic process, the relationship between pressure and temperature is given by: (/ r ) = (P/P r ) (k-1)/k (10 pt) For an ideal gas with constant specific heats undergoing an isentropic process, the relationship between specific volume and temperature is given by: (/ r ) = (v r /v) (k-1) 7. (10 pt)he ideal process for the isentropic efficiency is the isentropic process between the same pressures. 8. (10 pt)he isentropic process is also the reversible and adiabatic process. 9. (10 pt) In order to produce the maximum amount of work for a given enthalpy or specific internal energy change, there must be no heat trsansfer.
Lesson 32 1. (15 pt) Write the equation for the work transfer for a single-stream, steady-state, internally reversible system below: w vdp ke pe 2. (10 pt) How much work is produced by a single-stream, steady-state, internally reversible system with an isobaric process (you may neglect ke and pe)? zero 3. (10 pt) Work consumed by a single-stream, steady-state system undergoing an internally reversible process is represented by the area to the left of the process line on a P-v state diagram. 4. (15 pt) Write the equation for the work produced by a single-stream, steady-state, internally reversible system undergoing a constant volume process below: w = -v(p 2 -P 1 ) 5. (15 pt) Write the equation for the work produced by a single-stream, steady-state, internally reversible system through which an ideal gas (with constant specific heats) flows while maintaining a constant temperature below: w = -Rln(P 2 /P 1 ) 6. (15 pt) Write the equation for the work produced by a single-stream, steady-state, internally reversible system through which an ideal gas (with constant specific heats) flows while maintaining a constant entropy below: R P ( k1)/ k 1 2 w k 1 P 1 1 7. (10 pt) During an adiabatic expansion of an ideal gas from a high to a low pressure, the final temperature is greater than or equal to that predicted by the isentropic expansion equations. 8. (10 pt) During an adiabatic compression of an ideal gas from a low to a high pressure, the final temperature is greater than or equal to that predicted by the isentropic expansion equations.
Lesson 33 1. (10 pt) Cold-air standard analysis assumes the specific heats of the working gas are constant while hot-air standard analysis assumes the specific heats vary with temperature. 2. (10 pt) Air-standard analysis treats the combustion process as a heat addition process and the intake-exhaust processes as a heat rejection process. 3. (20 pt) he bore of a reciprocating engine is the diameter of the cylinder and the stroke is the distance travelled by the piston between bottom-dead-center and top-dead-center. 4. (10 pt) he displacement volume is the volume swept by the crown of the piston as it moves from bottom-dead-center to top-dead-center. 5. (10 pt) he mean effective pressure is the constant pressure required to produce the same net work for the same engine displacement volume. 6. (20 pt) Spark-ignition engines are either two-stroke or four-stroke engines that execute a complete cycle once per revolution or twice per revolution, respectively. 7. (10 pt) Write the definition of the reciprocating engine compression ratio of below. v r v max min 8. (10 pt) he Otto cycle is made up of two constant volume heat transfer processes and two isentropic processes.
Lesson 34 1. (5 pt) he single parameter that influences the thermal efficiency of an Otto cycle is the compression ratio. 2. (15 pt) he diesel cycle is made up of a constant pressure heat addition, a constant volume heat rejection, and two isentropic processes. 3. (5 pt) he Brayton cycle represent s the ideal gas turbine. 4. (10 pt) he Brayton cycle is made up of two constant pressure heat transfer and two isentropic processes. Pmax 5. (10 pt) Write the definition of the gas turbine pressure ratio below. rp P 6. (10 pt) he principle deviations of actual gas turbines from the Brayton cycle are the efficiencies of the compressor and turbine. 7. (15 pt) List the components of the basic gas turbine below. (1) compressor, (2) combustor, and (3) turbine min 8. (5 pt) he maximum Brayton cycle temperature is limited by the turbine blades. 9. (10 pt) he back work ratio is defined as the ration of compressor work to the turbine work. 10. (10 pt) According to Carnot, the best way to increase the efficiency of a gas turbine is to increase the turbine inlet temperature. 11. (5 pt) he single most important parameter that influences the efficiency of a Brayton cycle is the pressure ratio.
Lesson 35 1. (5 pt) he single parameter that influences the thermal efficiency of an Otto cycle is the compression ratio. 2. (15 pt) he diesel cycle is made up of a constant pressure heat addition, a constant volume heat rejection, and two isentropic processes. 3. (5 pt) he Brayton cycle represent s the ideal gas turbine. 4. (10 pt) he Brayton cycle is made up of two constant pressure heat transfer and two isentropic processes. Pmax 5. (10 pt) Write the definition of the gas turbine pressure ratio below. rp P 6. (10 pt) he principle deviations of actual gas turbines from the Brayton cycle are the efficiencies of the compressor and turbine. 7. (15 pt) List the components of the basic gas turbine below. (1) compressor, (2) combustor, and (3) turbine min 8. (5 pt) he maximum Brayton cycle temperature is limited by the turbine blades. 9. (10 pt) he back work ratio is defined as the ration of compressor work to the turbine work. 10. (10 pt) According to Carnot, the best way to increase the efficiency of a gas turbine is to increase the turbine inlet temperature. 11. (5 pt) he single most important parameter that influences the efficiency of a Brayton cycle is the pressure ratio.
Lesson 36 1. (20 pt) List the 4 components of the basic Rankine cycle below: Pump, Boiler, turbine, condenser 2. (15 pt) he process occurring in the Rankine cycle boiler is an isobaric process that converts saturated liquid water into a superheated vapor. 3. (15 pt) Ideally, the turbine in a Rankine cycle is a adiabatic, reversible device in which the working fluid undergoes an isentropic process. 4. (10 pt) he Rankine cycle condenser is an isobaric process that converts water mixture into a saturated liquid. 5. (5 pt) he water passing through the pump is an incompressible substance. 6. (10 pt) he change in the enthalpy across the pump is given by: h v P 7. (10 pt) Write the definition of the heat rate below. 8. (5 pt)he boiler is also known as the. 9. (10 pt) Rankine cycles are not operated as Carnot cycles because of the problems with equipment operating with a 2-phase working fluid? rue/false