| Term | Definition |
|---|
| thermodynamics | the science that deals with heat and work and those properties of substances that bear a relation to heat and work |
| classical thermodynamics | based on data and postulates from experiments |
| system | a device or a combination of devices containing a quantity of matter that is being studied; the mass is enclosed by physical or imaginary boundaries |
| control volume | volume that surrounds the system |
| control surface | entire surface of control volume |
| surroundings | everything external to the system that can have an effect on the system behavior |
| closed system | no mass flow across boundaries |
| open system | one in which there is mass flow across the boundaries |
| adiabatic | no heat flow across the boundaries |
| isolated system | no interaction with surroundings; no heat, mass, or work across the boundaries of the system |
| intrinsic observation | an observation of the system without reference to the surroundings |
| extrinsic observation | an observation of the system obtained with reference to the surroundings |
| property | an observation, i.e. a measurement, that depends only on the state of the system |
| extensive property | one that depends on the size or total mass of the system: volume, total mass |
| intensive property | one that is independent on the extent or total mass of the system; intensive properties are characteristic of the system as a whole or any part of it: density, temperature, pressure |
| state | the condition of a system that is fixed by specifying values of the properties of the system |
| process | path followed by a system in undergoing a change in state |
| process | the path of succession of states through which a system passes |
| alternate definition of property | function that depends only on the initial and final states of the system and not the path followed |
| cycle | a process in which a system in an initial state goes through a change in state and returns to its initial state |
| reversible process | one that can be reversed in such a manner that both the system and the surroundings return to their initial conditions |
| heat | a form of energy which is transferred from one body to another due to a temperature difference (Q+ when added to system, Q- when added to surroundings) |
| work | the product of a force and the distance through which it acts |
| work | done by a system if the sole effect on the surroundings could be the raising of a weight (W+ when done by the system, W- when done on the system) |
| energy | the capability to produce an effect |
| equilibrium | a condition of a system such that the system can undergo no spontaneous or unaided changes |
| Newton's Second Law of Motion | F = ma/gc |
| atmospheric pressure | 14.69 lbf/in^2; 101,325 Pa; pressure due to atmosphere where a = 32.174 ft/s^2 = 9.8066 m/s^2 |
| absolute pressure | atmospheric pressure + gage pressure |
| gage pressure | difference between absolute pressure and atmospheric pressure |
| Zeroth Law of Thermodynamics | states that when two bodies have equality of temperature with a third body, they in turn have equality of temperature with each other |
| Ideal gas or perfect gas law | experiments show that the P-T-v behavior of gases is often given by the equation Pv = RT, P = (rho)RT |
| kilomole | the amount of substance in kg equal to the molecular weight |
| pound-mole | the amount of substance in lbm numerically equal to the molecular weight |
| Over what range is the ideal gas law accurate? | (1) at very low pressures on the order of 0.1 MPa, ideal gas behavior is accurate regardless of temperature, (2) at temperatures double the critical temperature, ideal gas behavior is accurate on the order of 10 MPa, (3) when the temperature is less than twice the critical temperature, and the pressure is above a very low value in the order of ambient, deviation from ideal gas behavior can be significant |
| phase | a quantity of matter that is homogenous throughout |
| pure substance | one that has a homogeneous and invariable chemical composition, even if there is a change of phase |
| saturated liquid | a pure substance that exists as a liquid at the saturation temperature and pressure |
| saturated vapor | a substance that exists as a vapor at the saturation temperature and pressure |
| compressed liquid (subcooled liquid) | a liquid whose temperature is lower than the saturation temperature at the existing saturation pressure |
| quality x | ratio of the mass of vapor to the total mass; pertains only to a substance that exists as part liquid and vapor at the saturation conditions |
| superheated vapor | a vapor whose temperature is greater than the saturation temperature |
| sublimation | the process by which a substance passes from solid to vapor |
| triple point | the P-T point at which a substance can exist as liquid, vapor, and solid |
| quasiequilibrium process | one in which the states the system passes through may be considered as equilibrium states; implies process is done slowly, implies gas pressure is uniform throughout the system |
| inexact differentials | differentials of path functions, written (delta)( ) |
| exact differentials | differentials of properties, written d( ) |
| power | the time rate of work |
| heat | energy transferred from one body to another because of a temperature difference |
| First Law of Thermodynamics | if a closed system undergoes a change in state from (1) to (2) involving energy transfer in various amounts of heat and work, then the net sum of the heat and work, i.e. the net energy transfer, will be the same for all processes or sequences of processes between states (1) and (2) |
| Alternate First Law of Thermodynamics | if any system is carried through a cyclic process, then the net heat transfer during the cycle is equal to the net work during the cycle |
| internal energy of a system | that energy it possesses by virtue of, by the presence of, and by the relative position and movements of its molecules, atoms, and subatomic units |
| heat capacity (c) | experimental, not a property |
| c(sub v) | volume specific heat, specific heat at constant volume |
| c(sub p) | specific heat at constant pressure |
Combine with other sets
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