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Thermals Exam 1
RPI Thermals and Fluids Exam 1 Vocab
Question | Answer |
---|---|
Thermodynamics | The science of the conversions between forms of energy and their relations to the macroscopic measurable quantities |
Heat Transfer | Transmission of thermal energy from a hotter object to a cooler object via conduction, convection, or radiation |
Control Volume | Arbitrary volume where mass and energy flow through |
System | A flexible, fixed or moving boundary that encloses the same particles at all times |
Closed System | Also called controlled mass system (no mass can cross boundary) |
Open System | Also called Control Volume (mass and energy can cross boundary) |
Isolated System | no mass or energy can cross boundary |
First Law of Thermodynamics | energy cannot be created or destroyed only transformed |
Specific Heat | The energy required to raise the temperature of a unit mass of substance by one degree |
Ideal Solids and Liquids | Does not change volume with temperature, cannot be compressed |
Dimension | Physical Quality |
Units | Magnitudes assigned to dimensions |
Extensive Properties | The value of an overall system is the sum of its values for the parts into which the system is divided |
Intensive Properties | Non additive properties |
Property | Macroscopic characteristic of a system to which a numerical value can be assigned without the knowledge of the history of the system |
Fluid Mechanics | The study of fluids at rest or in motion and the interactions between a solid and a fluid either flowing past or acting on the solid in some manner |
Boundary or Control Surface | Drawn around the system for the identification |
Surroundings | Everything outside the boundary |
Process | occurs when some property changes or energy flows |
Unsteady/ Transient | Properties of interest are different at start and finish |
Steady | Property does not vary with time only location |
Schematic diagram | Shows relationship and interactions |
Assumption | Used to simplify a problem |
Conduction | Caused by molecular vibrations |
Convection | Moving fluid flows past a solid of a different temp |
Radiation | Occurs in a vacuum, transfer via electromagnetic waves |
Multimode | Multiple types of heat transfer used in one system |
Thermal Resistance | Resistance to heat transfer |
Hydro statics | Fluids at rest |
Fluid Dynamics | Relative motion between fluid and solid |
Fluid | A substance that will deform is a shear force is applied |
Temperature | Measure of the average kinetic energy of the molecules |
Polytropic Process | Relationship between pressure and volume |
Isobaric Process | Constant Pressure |
Isothermal Process | Constant Temperature |
Adiabatic Process | No Heat Transfer |
Continuum Assumption | Characterize the material as if it were infinitely divisible and not composed of discrete molecules |
Pressure | The force of the combined motion of many molecules |
Heat | Energy in motion across the boundary of a system |
Internal Energy | Energy is stored in a system |
Equilibrium | A state in which there are no imbalances in forces, temps, pressures, phases or chemical composition |
Quasi Equilibrium | one that passes through states of equilibrium (very slow process) |
Biot Number | The ratio of conductive resistance to convective resistance |
Fourier's Law of Conduction | Heat flows from hot to cold based on thermal Conductivity |
Black Surface | Ideal Surface for radiation - one that absorbs all the radiation incident upon it |
Gray Surface | If a fraction of the incident radiation reflected by the surface is independent of the wavelength of the incident radiation |
Diffuse Surface | if the fraction of the incident radiation does not depend on the angle of incident |
Resistance analogy | Heat transfer rate is proportional to the temperature difference |
Lumped System Approximation | If two thermal resistances are being used and one is much larger than the other |
Fourier Number | Ratio of the rate at which heat is conducted through a body to the rate at which it is stored |