| Adiabatic process | is a process during which there is no heat transfer. The word adiabatic comes from the Greek word adiabatos, which means not to be passed.
|
 |
|
|
| Boundary work (PdV work or moving boundary work) | is the work associated with the expansion or compression of a gas in a piston-cylinder device. Boundary work is the area under the process curve on a P-V diagram equal, in magnitude, to the work done during a quasi-equilibrium expansion or compression process of a closed system.
|
|
|
|
| Closed system | consists of a fixed amount of mass, and no mass can cross its boundary. But energy, in the form of heat or work, can cross the boundary.
|
|
|
|
| Conservation of energy principle | or energy balance based on the first law of thermodynamics for closed systems may be expressed as follows: Energy can be neither created nor destroyed; it can only change forms. The net change (increase or decrease) in the total energy of the system during a process is equal to the difference between the total energy entering and the total energy leaving the system during that process. The energy balance can be written explicitly as
Ein – Eout = (Qin – Qout ) + (Win – Wout ) = Δ Esystem
|
|
|
|
| Cycle | is a process, or series of processes, that allows a system to undergo state changes and returns the system to the initial state at the end of the process. That is, for a cycle the initial and final states are identical.
|
|
|
|
| Daily calorie needs | depends on the nutrition levels of people and will vary greatly with age, gender, the state of health, the activity level, the body weight, and the composition of the body as well as other factors.
|
|
|
|
| Electrical work | is work done on a system as electrons in a wire move under the effect of electromotive forces while crossing the system boundary.
|
|
|
|
| Enthalpy change of an ideal gas | is given as Δh = ∫CP(T)dT ≅ CP, av(T2 – T1).
|
|
|
|
| Formal sign convention | (classical thermodynamics sign convention) for heat and work interactions is as follows: heat transfer to a system and work done by a system are positive; heat transfer from a system and work done on a system are negative.
|
|
|
|
| Heat | is defined as the form of energy that is transferred between two systems (or a system and its surroundings) by virtue of a temperature difference.
|
|
|
|
| Ideal gas specific heat relation | is Cp = Cv + R.
|
|
|
|
| Incompressible substance | is a substance whose specific volume (or density) is constant.
|
|
|
|
| Internal energy change of an ideal gas | is given as Δu = ∫Cv(T)dT ≅ Cv, av(T2 – T1).
|
|
|
|
| Metabolism | is the thousands of chemical reactions that occur every second in the cells of a body during which some molecules are broken down and energy is released and some new molecules are formed. This high level of chemical activity in the cells maintains the human body at a temperature of 37°C while performing the necessary bodily tasks.
|
|
|
|
| Moving boundary work | (see boundary work).
|
|
|
|
| Polytropic process | is a process in which pressure and volume are often related by PVn= C, where n and C are constants, during expansion and compression processes of real gases.
|
|
|
|
| Rate of heat transfer | is the amount of heat transferred per unit time.
|
|
|
|
| Shaft work | is energy transmitted by a rotating shaft and is the related to the torque T applied to the shaft and the number of revolutions of the shaft per unit time.
|
|
|
|
| Specific heat | is defined as the energy required to raise the temperature of a unit mass of a substance by one degree. In general, this energy will depend on how the process is executed.
|
|
|
|
| Specific heat at constant pressure Cp | is the energy required to raise the temperature of the unit mass of a substance by one degree as the pressure is maintained constant. Cp is a measure of the variation of enthalpy of a substance with temperature. Cp can be defined as the change in the enthalpy of a substance per unit change in temperature at constant pressure.
|
|
|
|
| Specific heat at constant volume Cv | is the energy required to raise the temperature of the unit mass of a substance by one degree as the volume is maintained constant. Cv is related to the changes in internal energy.It would be more proper to define Cv as the change in the internal energy of a substance per unit change in temperature at constant volume.
|
|
|
|
| Specific heats for solids and liquids | or incompressible substances, are equal.
|
|
|
|
| Specific heat ratio | k is defined as the ratio Cp/Cv.
|
|
|
|
| Spring work | is the work done to change the length of a spring.
|
|
|
|
| Work | is the energy transfer associated with a force acting through a distance.
|