Thermodynamics

For reversible cycles, the temperatures on this scale are called __________.

A) Absolute temperatures*** B) Gage temperatures C) Saturation temperatures D) Reduced temperatures

Which one in the following is NOT an application of the Second Law?

A) Determine the performance limit of a system B) Identify the direction of energy transfer C) Quantify the energy transfer from one form to another*** D) Evaluate the "availability" of energy to produce work

The reversed Carnot cycle is also called Carnot _____ cycle ?

A) Engine B) Refrigeration*** C) Isothermal Compression D) Adiabatic Expansion

In the Clausius Inequality, the T are the _________ of the boundaries.

A) Gage temperatures B) Absolute temperatures*** C) Reduced temperatures D) Critical temperatures

Following processes are always considered as irreversibility, EXCEPT

A) Mixing of two fluids B) Chemical reaction C) Unrestrained expansion D) Slow compression***

The Clausius Inequality, works for ____________ .

A) Reversible process B) Irreversible process C) All of above***

In the Clausius Inequality, the δQnet is _________.

A) The net heat ejected from the system B) The net heat added to the system*** C) The heat extracted from the high temperature reservoir D) The heat extracted from the low temperature reservoir

What does COP = 1 for a heat pump (HP) represent?

A) violation of the 1st law B) violation of the 2nd law C) electric heating*** D) refrigeration

Kelvin-Planck statement told us engine efficiencies must be less than 100%. This is equivalent to say, in the heat engine design,

A) work output is greater than work input. B) work input is required. C) heat rejection is required.*** D) heat source is required

Which one is correct about two processes in the following?

A) ΔSA = ΔSB *** B) ΔSA > ΔSB C) ΔSA < ΔSB D) All of above are possible

How many isentropic processes in a standard Carnot power cycle?

A. 0 B. 1 C. 2*** D. 4

How many reversible isothermal cycle does the Carnot cycle have?

A. 0 B. 1 C. 2*** D. 4

In Carnot Power Cycle, which process is so called "reversible isothermal heat addition" process?

A. 1-2*** B. 2-3 C. 3-4 D. 4-1

The following refrigerator directly violates _________.

A. 1st law of thermodynamics B. Kevin-Planck statement of 2nd law C. Clausius statement of 2nd law***

A heat pump uses _____ as a heat source.

A. Air indoors B. Air outdoors*** C. Refrigerant D. Compressor

Entropy generation, Sgen, of a reversible process is ______

A. Always positive B. Always negative C. Always zero*** D. Uncertain

Which one of the following regarding "Isolated System" is NOT true?

A. An isolated system is a general system of fixed mass. B. An isolated system can be an open system or a closed system. *** C. Neither heat nor work can cross the isolated system boundary D. An isolated system is a collection of a main system and its surroundings.

Which device in the steam plant consumes work?

A. Boiler B. Turbine C. Condenser D. Pump***

What is correct for describing the entropy change in an irreversible process in general?

A. Can not decrease B. Can not increase C. Remains zero D. None of above***

Which one is correct for the description of the entropy change of an isolated system?

A. Can not decrease*** B. Can not increase C. Remains zero D. Uncertain

Consider an adiabatic and irreversible process, the entropy ______ .

A. Can only increase.*** B. Can only decrease. C. Is zero. D. All of above are possible.

Conservation of Volume always works for ______

A. Closed systems B. Open systems C. Isolated systems D. None of above***

Conservation of Mass works for ______

A. Closed systems only B. Open systems only C. Isolated systems only D. All of above***

To find the exit flow velocity, a garden hose is modeled as a ________ device.

A. Compressor B. Pump C. Nozzle*** D. Diffuser

Which one of the following devices is mainly used to handle liquids?

A. Compressor B. Turbine C. Pump*** D. Fan

Which one of the following devices need a work input?

A. Compressor*** B. Turbine C. Diffuser D. Nozzle

The following devices are primarily used to increase the pressure of a fluid, EXCEPT for:

A. Compressors B. Nozzles*** C. Fans D. Pumps

All of the following devices will experience an increase of the gas pressure, EXCEPT?

A. Compressors B. Turbines*** C. Diffusers D. Fans

Which one is a conservation principle in the Thermodynamics?

A. Conservation of heat. B. Conservation of volume. C. Conservation of energy.*** D. Conservation of internal energy.

Which one is NOT a conservation principle in thermodynamics?

A. Conservation of mass. B. Conservation of volume.*** C. Conservation of energy. D. None of above

Throttling valves can be used for the following tasks, EXCEPT?

A. Control flow B. Flow rate measurement C. Large change in fluid velocity*** D. Provide temperature drop

Which one of following is NOT a conservation principle?

A. Conversation of energy B. Conservation of mass C. Conservation of entropy*** D. None of above

The main purpose of a turbine is to __.

A. Convert kinetic energy into enthalpy B. Convert enthalpy into internal energy C. Convert enthalpy into work*** D. Cause a drop in pressure

_________ in energy quality is always accompanied by an increase in entropy?

A. Decrease*** B. Increase C. Unchanging

The following assumptions (including thermo laws) were used to derive T ds relations, EXCEPT

A. Energy conservation B. Internally reversible C. Closed system D. SSSF***

The following statement regarding entropy is generally correct, EXCEPT

A. Entropy change for a process can be negative. B. Entropy generation can not be zero*** C. No entropy generation in a Carnot heat engine. D. Both positive entropy change and negative entropy change happen in Carnot cycles.

The following statements are correct, EXCEPT

A. Entropy generation can not be negative. B. Entropy change can be negative. C. Entropy generation must be positive for irreversible processes. D. Entropy change can not be negative for isothermal processes.***

What do you conclude about the following two integrals (do not depend on path!)?

A. Equal with opposite signs B. Equal with same signs*** C. No need to be equal, always same signs D. No need to be equal, can be any signs

Consider a cycle composed of a reversible and an irreversible process, the entropy change of the cycle is _____________

A. Greater than 0 B. Less than 0*** C. Equal to zero D. S2 - S1

The quality of energy is related to how much _______ we can get out of the energy.

A. Heat B. Work*** C. Temperature D. Enthalpy

According to the 2nd law, all following statements are true, EXCEPT?

A. Heat can only be transferred from high temperature to low temperature B. Heat can be directly converted to work*** C. Work can directly generate electricity D. Work can be directly converted to heat

The mechanical work can only be obtained when __________.

A. Heat flows from high T to low T.*** B. Heat flows from low T to high T. C. It's operated in an open system. D. Ideal gas is used as the flowing fluid

Entropy generation, Sgen, is a measure of ___.

A. Heat transfer B. Work output C. Irreversibility*** D. Temperature change

How do our hands get warm if we rub them together constantly?

A. Heat transfer from the blood to the hands B. Work is transformed to heat*** C. Friction is transformed to work D. Reversible processes produces heat

The " Caloric" in thermodynamics history was equivalent to ________ in modern thermodynamics.

A. Heat*** B. Work C. Internal energy D. Flow energy

The third law of thermodynamics states that the entropy of a pure _________ at absolute zero temperature is zero

A. Ice B. R-134a C. Diamond D. Crystal***

What is the most important assumption to have (V_in)(A_in) = (V_out)(A_out) ?

A. Incompressible*** B. SSSF C. Adiabatic D. Ideal gas

The temperature of an ideal gas ________ when it is throttled to a lower pressure.

A. Increases B. Decreases C. Remains the same*** D. Cannot be determined

Nozzles are the engineering devices that are used for ____________.

A. Increasing the system kinetic energy B. Increasing the system potential energy C. Increasing the system internal energy D. Increasing the total flow energy***

For incompressible substances, if a process is reversible & adiabatic, it must also be _________ .

A. Isobaric B. Isochoric C. Isothermal*** D. Indeterminate

The Clausius statement of the 2nd law of thermodynamics directly tells us that ________

A. It is possible to design a 100% efficient heat engine B. The COP of a heat pump can not be infinity*** C. The COP of a heat pump must be greater than 1 D. A heat engine must reject heat

What does COP = infinity for a heat pump directly violate?

A. Kevin-Planck statement of 2nd law of thermodynamics B. Clausius statement of 2nd law of thermodynamics*** C. Carnot principle 1 D. Carnot principle 2

What's the heat source for a refrigerator device?

A. Kitchen air B. Refrigerated space*** C. Refrigerant from the compressor D. Refrigerant from the expansion valve

Mass flow rate can be calculated by __________.

A. Mass times velocity B. Mass times volume flow rate C. Density times velocity D. Density times volume flow rate***

Steady-flow assumption is for simplifying the conservation of mass by __________?

A. Neglecting the rate of change of total mass entering CV B. Neglecting the rate of change of total mass leaving CV C. Neglecting the rate of change in CV mass*** D. Neglecting CV kinetic energy

What is the best description of the following device in thermodynamics? --<

A. Nozzle B. Pipe C. Heat exchanger D. Mixing chamber***

Which device in the following will experience small pressure change of flow from inlet to outlet?

A. Nozzle*** B. Pump C. Turbine D.Compressor

The T ds relations are valid for _______ processes.

A. Reversible B. Irreversible C. Isentropic D. All of above***

Isentropic process is _________

A. Reversible B. Iso-thermal C. Adiabatic D. Iso-entropy***

From the example in our textbook, COPR = 11, here, the subscript R denotes_______.

A. Reversible process B. Reduced pressure C. Refrigerator*** D. Ratio of Q and W.

Generally, we use the following assumptions for designing a NOZZLE, EXCEPT?

A. SSSF B. Adiabatic C. ∆PE = 0 D. ∆KE = 0***

A diffuser is a device that increases the pressure of a fluid by ______

A. Slowing it down*** B. Speeding it up C. Keeping it stationary

A work reservoir is a sufficiently large system to which finite amounts of work can be transferred adiabatically without any change in its ______?

A. Temperature B. Enthalpy C. Pressure*** D. Specific volume

The following are possible ways for improving the heat engine efficiency EXCEPT:

A. The QL rejected to a low-temperature sink can be collected to increase QH*** B. The working fluid can be modified to quickly reach the state beyond the critical point C. The TH can be higher by using a new furnace D. The TL can be lower by finding a colder place

The Clausius inequality (<0) is satisfied for a cycle. The follow conclusions are correct, EXCEPT

A. The cycle has at least one irreversible process. B. The cycle is irreversible. C. All processes of the cycle are reversible.*** D. The net Q over all boundaries can not be positive

A cylinder fitted with a frictionless piston contains an ideal gas at temperature T and pressure P. If the gas expands isothermally until the pressure is P/5, the work done by the gas is equal to?

A. The heat absorbed by the gas*** B. The internal energy changed of the gas C. The enthalpy change of the gas D. 5P times the volume change in the gas

If the entropy change of a process is zero, then ___________

A. The process must be reversible B. The process must be adiabatic C. The process must be isentropic D. None of above***

The following statements are always true for Steady-State, Steady-Flow Processes, EXCEPT?

A. The states of the mass streams crossing the boundary are constant with time. B. No rate change in internal energy, kinetic energy, and potential energy. C. No heat is transferred to the control volume.*** D. No boundary work is done.

To solve for the air temperature at the exit of a hair dryer, the problem should be modeled as a ______ problem.

A. Throttling B. Fan*** C. Nozzle D. Compressor

Which device in the following will experience larger pressure drop of flow from inlet to outlet?

A. Throttling B. Pipe/Duct C. Turbine*** D. Compressor

To solve the fluid temperature at the shower exit, the best way is to model the following device as a _________ problem (resistance heater controls temperature).

A. Throttling B. Pipe/Duct*** C. Heat Exchanger D. Mixing Chamber

To solve the steam pressure at the exit of a pressure cooker, the problem should be modeled as a _________ problem.

A. Throttling*** B. Pipe/Duct C. Nozzle D. Compressor

What's the best description of the process for a system with boundary temp. equal to reservoir temp. but not inside temp.?

A. Totally reversible B. Internally reversible C. Externally reversible*** D. Irreversible

The thermal efficiency of the Carnot heat engine is 100% because all processes are considered reversible.

A. True B. False***

Two heat engines operating between the same high- and low-temperature reservoirs have the same thermal efficiency.

A. True B. False***

According to the 2nd law of thermodynamics, whenever energy transforms, some of it degenerates into waste energy.

A. True*** B. False

For solving a heat changer problem, a CV is chosen as below. Then this problem becomes to an adiabatic process.

A. True*** B. False

High temperature energy can produce more work than low temperature energy.

A. True*** B. False

Which one describes the fact of a device which is claimed transferring heat to rotate a paddle wheel?

A. Violates both 1st law and 2nd law B. Satisfies 1st law, violates 2nd law*** C. Violates 1st law, satisfies 2nd law D. Satisfies both 1st law and 2nd law

Which one in the following has the same cyclic integral as the entropy?

A. Volume*** B. Heat C. Work

What's the desired result for a refrigerator device?

A. Win B. Wout C. QH D. QL***

In the h-s diagram, for adiabatic steady-flow devices, the horizontal distance Δs is a measure of _________

A. Work B. Heat transfer C. Irreversibility*** D. Clausius inequality

Flow energy flowing into or from the system is ______

A. a dynamic form of energy*** B. a static form of energy C. not a form of energy

A Carnot cycle is also __________.

A. an adiabatic cycle B. an isothermal cycle C. a reversible cycle*** D. a compression cycle

Execution of the Carnot engine cycle is in _____?

A. an open system B. a closed system*** C. an isolated system D. a mixed closed and open system

When two fluid streams are mixed in a mixing chamber, the mixture temperature is lower than the temperature of both streams only if _______

A. both streams are not SSSF B. both streams are liquid-gas mixtures C. there exists heat loss to surrounds*** D. there exists word done to the system

A nozzle is a device that increases the velocity of a fluid at the expense of ______

A. density B. pressure*** C. temperature D. internal energy

For an internally reversible process, entropy change is _______.

A. equal to zero B. positive C. negative D. all of above***

A cycle consists of a series of processes that __.

A. eventually return to the first state of the first process*** B. are continually repeated C. are always in equilibrium or quasi equilibrium D. none of above

When a substance melts, its entropy _________

A. increases*** B. decreases C. remains the same

For incompressible substances in a closed system, if a process is reversible & adiabatic, its work input must be _________ .

A. positive B. negative C. zero*** D. all of above

For ___________, both volume flow rate and mass flow rate remain constant for an open system.

A. superheated vapor B. liquid-vapor mixture C. incompressible flow*** D. ideal gas

After passing through a throttling valve, ______ of the fluid flow will be dropped?

A. temperature B. enthalpy C. pressure*** D. mass flow rate

Which one can best represent the "Total Flow Energy" for an open system?

A. u B. Pv C. u+Pv D. u + Pv + V^2/2 + gz***

Which one can best represent the "Flow Work" for an open system?

A. u B. Pv*** C. u+Pv D. u + Pv + V^2/2 + gz

Which equation can lead to find heat transfer per unit mass , q?

A. 𝑞 =𝑄 𝑚 B. 𝑞 = 𝑄 𝑚 C.𝑞 = 𝑄 𝑚*** D. 𝑞 =𝑢 𝑚

The temperature of _________ remains the same when it is throttled to a lower pressure.

a) Incompressible liquid b) Compressible liquid c) Ideal gas*** d) Vapor-water mixture

An ideal gas undergoes an isothermal process. The enthalpy of the substance ________.

a) Increases b) Decreases c) Remains the same*** d) Indeterminate

Throttling valves can be used for _________ .

a) Increasing temperature. b) Flow rate measurement*** c) Large change in fluid velocity d) Decreasing enthalpy

Which one of following is a good example of a heat sink?

a. A lake*** b. The sun c. A refrigerator d. A cup of cold coffee