Thermodynamics Flashcards
This involves the storage, transformation and transfer of energy.
Thermodynamics
A volume into which and/or from which a substance flows. It is also an open system.
Control Volume
It is composed of a single phase, free of magnetic and electrical surface effects. It only needs two properties to fix it.
Simple System
It is the condition of a system described by giving values its properties at the given instant.
State
It is the property of matter that is independent on the mass
Intensive Property
It is the property of matter that is dependent on the mass
Extensive Property
It is an extensive property divided by the mass.
Specific Property
It happens when the properties do not vary from point to point in a system and there is no tendency for additional change.
Thermodynamic Equilibrium
It is the path of successive states through which a system passes
Process
It is phenomenon where, if in passing from one state to the next, the deviation from equilibrium is infinitesimal. It is also called a quasi static process.
Quasi-Equilibrium
It is a process in which, when reversed, leaves no change in either the system or surroundings.
Reversible Process
It is a process where the temperature is constant
Isothermal Process
It is a process where the pressure is constant
Isobaric
It is a process where the volume is constant.
Isochoric/Isovolumetric/Isometric
It is a kind of process where there is no heat transfer.
Adiabatic
It is defined as the degree of hotness or coldness of a certain substance with respect to some standard value. It is a property that is dependent on the substance’s energy content.
Temperature
It it is a measure of the average kinetic energy of the different particles in a sample of matter
Temperature
This states that if two bodies are equal in temperature to a third, then they are equal in temperature.
Zeroth Law of Thermodynamics
This states that during a given process, the net heat transfer minus the net work equals the change in energy
First Law of Thermodynamics
This states that a device cannot operate in a cycle and produce work output while exchanging heat with a single constant temperature reservoir.
Second Law of Thermodynamics
This states that the volume varies inversely with pressure for an ideal gas.
Boyle’s Law
This states that the volume varies directly with temperature for an ideal gas
Charles’ Law
It states that equal volumes of different ideal gases with the same temperature and pressure contain the equal number of molecules.
Avogadro’s Law
1 atm = ____ psi
14.7
1 atm = ____ kPa
101.325
1 atm = _____ mm Hg
760
1 atm = ____ in Hg
29.92
1 atm = ____ torr
760
1 atm = _____ bar
1.01325
What is the freezing point for the Fahrenheit scale?
32
What is the boiling point for Fahrenheit Scale
212
Temp in Kelvin = Temp in Celsius + _______
273.15
Temp in Rankine = Temp in Fahrenheit + _________
460
What is the value for universal gas constant (R) in J/mol*K ?
8.314
It encompasses all of potential and kinetic energies of the atoms or molecules of a substance. It is a function of temperature and is expressed in kJ/kg or Btu/lbm.
Internal Energy
It is a property which represents the total useful energy in the substance, It consists of the Internal energy and the flow energy.
Enthalpy
It is the measure of energy which is no longer available to perform work within the current environment. The total unavailable energy in a system and is equal to the summation of all unavailable energy inputs over the life of the system
Entropy
It is the form of energy associated with the kinetic random motion of large no. of molecules
Heat
It is the heat needed to change the temperature of the body without changing its phase.
Sensible Heat
It is the quantity of heat required to change the temperature of unit mass through one degree.
Specific Heat
What is the specific heat of water in kcal/kg*degC?
1 kcal/kg*degC
What is the specific heat of ice in kcal/kg*degC?
0.5 kcal/kg*degC
What is the specific heat of steam in kcal/kg*degC?
0.4
It is defined as the heat capacity per unit mass.
Specific Heat
What is the formula for Linear Expansion?
∆L = αL∆T
What is the formula for Volume Expansion?
∆V = βV∆T
The coefficient of volume expansion, β, is _______ times the coefficient of linear expansion α
three (3)
1 cal = _____ J
4.186
1 BTU = _______ cal
252.16
1 BTU = ______ J
1055.06
It is the heat required to change the state of the substance from solid to liquid and to gas without changing in temperature
Latent Heat
It is the latent heat in changing solid to liquid
Latent Heat of Fusion (Lf)
What is the Lf of ice in kJ/kg?
333.5
What is the Lf of ice in cal/g?
79.7
What is the Lf of ice in BTU/lbm?
143.4
It is the latent heat in changing liquids to gas.
Latent heat of vaporization
It is the latent heat for changing from solid to gas.
Latent heat of sublimation
What is the Lv of water in kJ/kg
2256.7
What is the Lv of water in cal/g?
539.1
What is the Lv of water in BTU/lbm?
970.3
It refers to the amount of heat to be supplied to an object to produce a unit change in its temperature.
Heat Capacity
It is a mode of heat transfer in which heat is transferred by molecular interaction through bodies in contact.
Conduction
It refers to the transfer of thermal energy between neighboring molecules in a substance due to a temperature gradient
Thermal Conduction
It states that the time rate of heat to transfer through a material is proportional to the gradient in the temperature and to the area, at right angle to the gradient, through which the heat is flowing.
Fourier’s Law of Thermal Conduction
What is the formula for Thermal Conduction?
Q = (kAtΔT) / L
where: k = thermal conductivity constant A = area t = time L = thickness of slab/material ΔT = change/difference in temperature
It is the insulating ability of a layer of material
Thermal Resistance (R)
What is the formula for Thermal Resistance R
R = L/k
where
L= thickness of slab/material
k = thermal conductivity constant
It is a heat transfer between bodies by energy propagating electromagnetic waves
Radiation
Formula for Heat Transferred by Radiation
Q= eσA(T1^4 - T2^4)
It states that all energy received as heat by a heat-engine cycle cannot be converted into mechanical work
Second Law of Thermodynamics
Whenever energy is transferred, some energy is ______________.
reduced to a lower level
No heat cycle is possible without _____________.
the rejection of some heat
It is the cycle that converts the maximum amount of heat into work, it has the highest thermal efficiency. It also operates between two temperature reservoirs having the same efficiency.
Carnot Cycle
A Carnot machine’s efficiency, or Coefficient of Performance is a function of _____________.
the two reservoir temperatures
It states that it is impossible to construct a device which operates on a cycle and whose sole effect is the transfer of heat from a cooler body to a hotter body.
Clausius’ Statement of the Second Law
It states that it is impossible to construct a device which operates on a cycle and produces no other effect than the operation of work and the transfer of heat from a single body.
Kelvin-Planck Statement on the Second Law
Natural processes ( which typically involve friction) result in a/n ___________ in entropy
Increase
Entropy will ________ when heat is added
increase
Entropy will ________ when processes are reversible and adiabatic.
remain constant
Entropy can decrease only when ___________.
heat is removed.
It operates the most efficiently between a high temp reservoir and a low temp reservoir
Carnot Cycle
It is the ration of useful heating or cooling provided to work (energy) required.
Coefficient of Performance
It is the ratio of the net work output to the net heat input
Thermal/Cycle efficiency
It is the process widely used by power plants such as coal-fired PP and Nuclear PP
Rankine Cycle
It is a mechanical cycle commonly used in power plants to convert the pressure energy of steam into mechanical energy through steam turbines
Rankine Cycle
This system is like a heat engine operating in reverse and is typically referred to as a reverse Carnot Engine. It is used in refrigeration and for lowering temperatures because it involves the transfer of heat from a cold reservoir to a hot reservoir.
Vapor Compression (Refrigeration) Cycle
It is a cycle that describes how gas turbines operate.
Brayton Cycle
It is a cycle that describes how a heat engine extracts energy from the flowing fuel and air to produce useful work, which is further uses to drive a vehicle by providing it thrust. This cycle is also referred to as the Joule cycle.
Brayton Cycle
It describes how heat engines turn gasoline into motion.
Otto cycle
It describes how internal combustion engines (that use gasoline) work, like automobiles and lawn mowers.
Otto cycle
An example of an SI Engine (Spark Ignition Engine)
Petrol Engine
An example of CI (Compression Ignition) Engine
Diesel Engine
Cycles that are used to describe engines uses Internal Combustion.
Otto Cycle and Diesel Cycle
Diesel Engine operates at _________ compression ratio than Otto cycle
higher
It is a system where mass can flow through it. It allows energy to enter or leave.
Open System
It is a system where matter enters the system at the same rate that it leaves
Steady Flow Open System
It is a system where no mass can cross the system boundary
Closed System
It is the heat energy transferred to a substance at a constant pressure process
Enthalpy
The state of a thermodynamic system is always defined by its:
properties
Mathematically, a thermodynamic property is a ________.
point function
In a non-quasistatic thermodynamic process, the overall entropy in an isolated system will _________
increase
Entropy is the measure of ________
randomness or disorder
U + PV is a quantity called?
Enthalpy
It is the process that has no heat transfer in and out of the system.
Isentropic (Adiabatic) Process
The rate of heat transfer through a given section of a uniform wall for a given temperature difference is ___________ proportional to the thermal conductivity and ____________ inversely to the thickness of the wall.
directly, inversely
How is the quality, x, of a liquid-vapor mixture defined?
the fraction of the total mass that is saturated vapor.
The first law of thermodynamics is based on the principle of?
Conservation of Energy
What is the value of the work done for a closed, reversible isometric system
Zero
During an adiabatic, internally reversible process, what is true about the change in entropy.
It is always zero
For which type of process does the equation dQ=TdS hold?
reversible
Which thermodynamic cycle is the most efficient?
Carnot Cycle
The ideal reversible carnot cycle involves four basic processes. What types of processes are they?
two isothermal and two isentropic
Which of the following is not an advantage of a superheated, closed Rankine cycle over an open Rankine Cycle?
A. Increased boiler life
B. Lower equipment costs
C. Increased turbine
D. Increased efficiency
A. Increased boiler life
What type of cycle is described by this set of reversible process?
Adiabatic Compression - Isometric Heat addition - Adiabatic expansion - Isometric heat rejection.
Otto cycle
What type of cycle is described by this sequence of processes?
Adiabatic/Isentropic Compression - Isobaric Heat addition - Adiabatic/Isentropic Expansion - Isometric Heat rejection
Diesel cycle
What type of cycle is described by this sequence of processes?
Adiabatic/Isentropic Compression - Isobaric Heat addition - Adiabatic/Isentropic Expansion - Isobaric Heat rejection
Rankine Cycle
What type of cycle is described by this sequence of processes?
Adiabatic/Isentropic Compression - Condensation - Throttling - Evaporation
Vapor Compression/Refrigeration Cycle
For most solids, the coefficient of volume expansion is _________ the coefficient of linear expansion
Three times
The volume of a given amount of water ________ as the temperature decreases?
increases
The temperature of equal volumes of two liquids are changed by the same amount. One liquid is observed to increase its volume twice as much as the other. The coefficient of volume of expansion of the liquid which expands the most is _______ the coefficient of volume of expansion of the other.
Twice
When a solid melts,
A. the temperature of the substance increases
B. The temperature of the substance decreases
C. heat leaves the substance
D. heat enters the substance
D. heat enters the substance
When given the temperature, amount, type and shape of the material, which of these are not helpful in determining the amount of its internal energy?
Shape of the material
On a day when the absolute humidity remains constant, what happens to the relative humidity when the temperature rises?
It decreases
Liquids, gases, metals, solids other than metals.
Which of these have the highest thermal conductivities?
metals
Aluminum, brass, glass, concrete
These are identical objects of four different materials and are heated to the same high temperature. You are required to quickly move them from one table to another using your bare hand. Which object is the least likely to burn your hand?
Glass
The sun transfers energy to the earth mainly by _______ while the energy is distributed over the earth primarily by __________.
radiation, convection
The temperature of an electric stove burner is raised from 300K to 600K. How much more energy does it radiate per second at the higher temperature than at the lower temperature?
Sixteen times
Black or silver.
These are the colors painted on two surface with equal exposure to the sun. Which would have the higher surface temperature? Which would cool quicker?
Black, black
A process in which a gas is compressed very quickly can be viewed as a/n __________ process.
adiabatic
An ideal gas has a Cp =7/2 R. What is the Cv for the gas?
5/2 R
The boiling of water into steam in an open container is an example of a/n _____________ process.
Isobaric
The area under the curve in a P-V diagram for a process is.
The network done during the process
Tenoerature, work, heat, internal energy
Which of these is a function of state for a thermodynamic system?
Internal energy
A heat engine is a device that
changes heat into mechanical work
Which liquid water is converted to steam at 100 deg C, the entropy of the water
increases
Which of the following statements about entropy is false?
A. the entropy of a mixture is greater than that of its components under the same condition
B. An irreversible process increases the entropy of the universe
C. Entropy has the units of heat capacity
D. The entropy of a crystal at 0 deg F is zero
D
A pump, tire, pressure cooker, turbine
Which of these would be considered a system rather than a control volume?
Tire
Temperature, Pressure, Velocity, Mass
Which of the following is an extensive p
Temperature, Pressure, Velocity, Mass
Which of the following is an extensive p
Temperature, Pressure, Velocity, Mass
Which of the following is an extensive p
Temperature, Pressure, Velocity, Mass
Which of the following is an extensive p
Temperature, Pressure, Velocity, Mass
\Which of these is an extensive property?
Mass
An automobile heats up while sitting in a parking lot on a sunny day. The process can be assumed to be
Isobaric
If a quasi-equilibrium process exists, we have assumed that
the pressure at any instant to be everywhere constant
A summary of experimental observations in the scientific community and is made into a statement can be called ________
a scientific law
The net entropy change in the universe during any real process
is positive
The change in thermodynamic availability is equal to
the maximum possible work output
Heat transfer decreases with increased
R-factor
It is the ratio of convective to conductive heat transfer across a boundary
Nusselt Number
It is a dimensionless number and is defined as the ratio of kinematic viscosity (v) to the thermal diffusivity (α)
Prandtl Number
It is a dimensionless quantity used to indicate the influence of gravity on fluid motion.
Froude Number
A given mass of gas in enclosed in a rigid container. If the velocity of the gas molecules colliding with the sides of the container increases, its pressure will _________.
increase
Aluminum, Iron, silver, copper
Which of these absorbs the most heat considering they are of equal masses?
Aluminum
A change in kinetic energy of the molecules of an object may best be detected by measuring change in the objects
temperature
As time passes, entropy ________.
increases
A thermodynamic process whose deviation from equilibrium is infinitesimal at all times is in ______
quasiequilibrium
A substance whose properties are uniform throughout is called a/n
pure substance
It is a substance whose temperature is equal to its saturation temperature
liquid and a vapor
If a substance’s temperature is greater than its saturation temperature, the substance is a
superheated vapor
The relationship between the total pressure of a mixture of nonreacting gases and the partial pressures of its constituents is given by
Dalton’s Law
It states that the total volume of a non-reacting mixture of gases at constant temperature and pressure should be equal to the sum of the individual partial volumes of the constituent gases.
Amagat’s Law
A series of processes that eventually bring the system back to its initial condition is called a ________
cycle
The compression ratio of an air standard Otto cycle is the ratio of
cylinder volumes
The compression ratio in a gas compression process is the ratio of the
Pressures
Humidification, sensible heating, natural convection, sensible cooling.
Which of these is not found on a psychrometric chart?
Natural Convection
Radiant heat transfer is best described by
Kirchoff’s Law of thermal radiation
