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What Is Thermodynamics
Thermodynamics is the science that deals with the relationship of heat and mechanical energy
how many properties do we need to solve for something in thermodynamics?
What cycles has:
- 2 isentropic process
- 2 constant pressure process
- is an ideal gas
Brayton Cycle
Is the power generated by fuel cells limited by the Carnot efficiency? Explain.
the power generated by fuel cells is not limited by the Carnot efficiency, as fuel cells operate on a different principle of converting chemical energy directly into electrical energy through electrochemical reactions.
NO!!!!!!!
Is entropy produced within a system undergoing a Carnot cycle? Explain.
NO!!!
which property is only between the values of 1 and 0.
quality
What type of power plant produces the electricity used in your residence?
Nuclear Power Plants
Coal Power Plants
Natural Gas Power Plants
According to Kelvin Plank, it is impossible to convert 100% of heat into work, true or false.
False. He stated that achieving 100% conversion of heat into work in a cyclic process, while interacting with only one reservoir, is impossible. However, it is possible to achieve complete conversion if the gas undergoes isothermal expansion while interacting with a single reservoir, allowing heat to be entirely converted into work.
In the differential form of the closed system energy balance, dE=δQ−δW, why is d and not δ used for the differential on the left?
The notation dE in the differential form of the closed system energy balance, dE=δQ−δW, uses the symbol d to represent an exact differential, while the symbols δQ and δW represent inexact differentials. In thermodynamics, an exact differential is used to represent a state function, while inexact differentials are used to represent path functions.
For an isolated system, the entropy can only increase. Does it have a maximum?
NO! in terms of classical thermodynamics and YES! in terms of statistical mechanics.
Name two intensive properties.
color, density, temperature, odor, melting/boiling point, rusting, luster.. any property that is independent on mass.
In which power cycle do most traditional car engines operate, involving constant volume heat addition and rejection?
The Otto cycle
Carnot cycle is well known as an ideal cycle, but why can't we obtain 100% efficiency from it?
Why is it incorrect to say that a system contains heat?
Heat is the transfer of thermal energy between two systems or between a system and its surroundings due to a temperature difference. Therefore, instead of saying a system "contains heat," it would be more precise to say that a system can exchange heat with its surroundings or undergo a heat transfer process.
What form does the energy balance take for an isolated system?
ΔU=0
what is the value of R (not the universal one) for air
0.287 J/g-K
What power cycle is often employed in large-scale power plants, utilizing compression and expansion processes with constant pressure heat addition and rejection?
The Rankine cycle.
Energy spreads out over time. Is it a valid definition of entropy?
Yes!
As a tree grows, its mass increases. Does this violate the conservation of mass principle? Explain.
No! In the case of a growing tree, the additional mass comes from the intake of nutrients, water, and carbon dioxide from the environment through processes such as photosynthesis.
IO 285
convert 20 m2/s2 to kj/kg
0.02
In which reversible thermodynamic cycle is the refrigeration process commonly used, involving the absorption of heat from a low-temperature reservoir?
The Reverse Carnot cycle.
Regrettably, my air conditioning fails in the summer. Being a trained engineer under Dr. Adams, I opt to open my refrigerator to cool down my apartment. Is this a prudent choice?
NO!!!!!! Opening your freezer is not advisable because your apartment acts as a hot reservoir for the refrigerator. Heat removal from the cold reservoir (freezer interior) requires energy, and this energy is used to transfer heat into your apartment, contributing to an increase in temperature. Essentially, opening the freezer would make your apartment warmer, as the electric power's energy is released into the apartment as heat.
What percentage of the energy received by Earth from the Sun is returned to the Universe?
100%