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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 |