THERMO FINALS Flashcards
describes that Not all energies used in a thermodynamic system are converted into equivalent amounts of work
SECOND LAW OF THERMODYNAMICS
This law demonstrates the impossibility of perpetual machines
Second law of thermo
he
statement is based on the concept of thermal efficiency. It states that a heat engine or similar
device cannot be 100% efficient.
A Kelvin-Planck statement
was based on the natural tendency of heat to flow from a high temperature region to a low temperature region
Clausius Statement:
The pressure developed by the cycle and is equivalent to the work net divided by the volume displacement.
Cycle Mean Effective Pressure
The most efficient cycle.
Carnot Cycle
Engines can be compared with this cycle to
determine its degree of perfection.
Carnot Cycle
is widely recognized as a reversible cycle and holds significant prominence in
thermodynamics.
Carnot Cycle
The Carnot cycle represents an _________ That exists without any imperfections found in
actual engines. However, it cannot be practically implemented in real-world applications.
Nevertheless, this theoretical engine serves as a benchmark for evaluating the performance of
real engines
Ideal heat engine
No matter how idealized the procedure may be, it is impossible to reduce the temperature of
any system to absolute zero in a finite number of operations
THIRD LAW OF THERMODYNAMICS
________ in a Carnot engine is solely
determined by the temperatures of the heat source and heat sink. It remains unaffected
by the specific properties of the working substance employed
Efficiency of energy conversion
TRUE OR FALSE
Even in highly idealized engines such as Carnot’s engine, it is possible for the
efficiency, denoted as e, of energy conversion to reach unity.
FALSE ITS NOT POSSIBLE
The equation mentioned above demonstrates that when the lowest conceivable
temperature (absolute zero) is denoted as TL = 0, the efficiency e equals ______.
1
TRUE OR FLASE
It is conceivable for e_cc to exceed 1. Therefore, this equation provides us with a reference
point for defining a temperature scale.
IT IS NOT CONCEIVABLE. FALSE!!!!
TRUE OR FALSE
It is impossible for any engine to surpass the efficiency of the corresponding Carnot
engine.
false
Which process?
The cylinder is placed on the source. The piston is
allowed to move out infinitely slowly reducing very gradually the weights on the piston. The gas
expands extremely slowly. As the gas expands, its temperature tends to fall. But since it is in thermal contact with the heat source therefore it will extract certain heat Q1 from the source. In
this way, the temperature of the gas remains constant at T1 throughout the
process of expansion
process 1-2 Isothermal Heat Addition
Which Process
he cylinder is placed on the insulated stand and the piston is allowed to move out. The gas expands isentropically from V2 to V3, till it falls to T2
Process 2-3 (Isentropic Expansion):
Which Process
he cylinder is placed on the sink and the gas is
isothermally compressed until the pressure at the bottom of the volume becomes P4 and V4,
respectively. The heat Q2 developed in compression is absorbed by the sink.
Process 3-4 (Isothermal Heat Rejection):
PROCESS?
The cylinder is placed in the insulating stand and the gas is compressed isentropically till it reaches its initial pressure P1, volume V1 and temperature
T1
Process 4-1 (Isentropic Compression):
This equation is one of the most radical generalizations in thermodynamics. The essence of the Second law of thermodynamics and also of the Third law of thermodynamics resides in this
result.
Thermal Efficiency of Carnot Cycle
The statement is based on the concept of thermal efficiency. It states that a heat engine or similar
device cannot be 100% efficient
Kelvin-Planck statement
FUN FACT
Refrigerators work on the second law of thermodynamics. In the process of refrigeration, unwanted heat is taken from one place and discharged into another. The common refrigerator which we have in our homes, works on the principle of evaporation
Noted
TRUE OR FALSE . explain
Heat pumps, air conditioners, and refrigerators utilize heat transfer from cold to hot. They are heat engines run backward.
TRUE
We say backward, rather than reverse, because except for Carnot engines, all heat engines, though they can be run backward, cannot truly be reversed. Heat transfer occurs from a cold reservoir Qc and into a hot one. This requires work input W, which is also converted to heat transfer.
soo kailangan ng external work para magkatotoo na yung temperature sa ref, hairblowers, etc will run from COLD TO HOT than the usual HOT TO COLD
TRUE OR FALSE
The lower the value of Cycle Mean Effective Pressure means higher work produced per
cycle and higher force per cycle output
FALSE
the higher the CMEP the higher the work produced
FUN FACT
A heat pump’s mission is for heat transfer Qh to occur into a warm environment, such as a home in the winter.
The mission of air conditioners and refrigerators is for heat transfer Qc to occur from a cool environment, such as chilling a room or keeping food at lower temperatures than the environment
NOTED
