property of any system that can be altered by relaxing constraints on the system
Define internal energy (U)
energy of the mass of molecules/atoms that make up matter; measurable by changes in temp, pressure, etc.
Define chemical energy
energy obtained when chemical bonds between atoms are made or broken
Define nuclear energy
energy contained within the (strong) bonds inside atomic nucleus; obtain through fusion/fission
Define electric/magnetic energy
polar molecules can store energy in the presence of magnetic/electric fields
amount of energy transferred by a force
What is the first law of thermodynamics?
Energy is conserved; that is, dE = dQ + dW + dU
What is the second law of thermodynamics?
Impossible to convert heat to work without consequences: 1) Conversion heat-->work always results in less work than heat invested, and 2) Heat can be released from sys only from higher-->lower temp
What is a reversible system?
Sys in which all processes (internal and external) conducted reversibly, i.e. without thermodynamic losses (no entropy/friction generated)
What is entropy?
Degree of disorder of a system
Why are reversible systems useful?
Don't exist in nature, but set an upper bound on the amount of energy that could be produced by a process
What is exergy?
Measure of the potential of energy to produce work
How do you calculate efficiency in energy chains?
η = useful E output / paid E input. Multiply all ηs.
What does the typical solar water heating system consist of?
1) solar collector and 2) storage tank
What is the difference between active and passive solar water heaters?
Active heaters use electric pumps to circulate water through collectors; passive use gravity and convection
Define capacity factor
ratio of net electricity generated to energy that could have been generated at full-power operation during a period of time
What are coal preparation technologies?
Cleaning of coal, removal of ash before combustion
What are coal upgrading technologies?
Increase Btu content of lower-ranked coals by removing water
What are coal treatment technologies?
Use additives to alter coal's combustion characteristics
What is conduction?
Conduction is the transfer of energy through matter from particle to particle.
What is radiation?
A way to transfer heat at a rate q from a body at a higher temperature T_hot to a body at lower temperature T_cold; as bodies radiate they lose energy