This glossary is for the class of heat transfer, and it´s designated to be the homework for the reading comprehension for this week.
Convection heat transfer coefficient
phrase
The rate of heat transfer between a solid surface and a fluid per unit surface area per unit temperature difference.
Example: As can be seen, the constant of proportionality will be crucial in calculations and it is known as the convective heat transfer coefficient, h. The convective heat transfer coefficient, h
es: Coeficiente de transferencia de calor por convección
Critical Reynold Number
phrase
It is the Reynold Number when some liquid becomes turbulent being laminar before of this number designated
Example: The critical Reynolds number for a laminar condition to prevail depends somewhat on the surface geometry
es: Número de Reynold crítico
Friction Coefficient
phrase
is a measure of the amount of friction existing between two surfaces. A low value of coefficient of friction indicates that the force required for sliding to occur is less than the force required when the coefficient of friction is high.
Example: Disc brake performance has shown to be dependant upon the geometry of the disc and pads, and the FRICTION COEFFICIENT between the pad material and the rotor.
es: coeficiente de fricción
Kinematic viscosity
is a measure of a fluid's internal resistance to flow under gravitational forces. It is determined by measuring the time in seconds
Example: This is not as intuitive as absolute viscosity as it would appear, take air as an example which under standard conditions has a higher KINEMATIC VISCOSITY than water owing to its lower density
es: Viscosidad cinemática
Laminar flow
conjunction
type of fluid (gas or liquid) flow in which the fluid travels smoothly or in regular paths, in contrast to turbulent flow
Example: Laminar flow is common only in cases in which the flow channel is relatively small
es: flujo laminar
Nusselt Number
phrase
this is a dimensionless heat transfer coefficient.
this heat is between a moving fluid and solid body
Example: the Nusselt number represents the enhancement of heat transfer through a fluid layer as a result of convection relative to conduction across the same fluid layer. The larger the Nusselt number, the more effective the convection.
es: Número de Nusselt
Prandlt number
phrase
this number is a product of the thermal boundary layers and the relative thickness of the velocity
icludes the viscosity and the absortivity
Example: In mechanical devices the Prandtl number is used especially in the study of heat transfer because it turns easier this study
es: número de Prandtl
Reynold number
phrase
it is used to determinate (in the external flow of a mechanism of heat transfer) if this are a laminar or turbulent fluid, this is a dimentionless quantity
Example: After exhaustive experiments in the 1880s, Osborn Reynolds discovered that the flow regime depends mainly on the ratio of the inertia forces to viscous forces in the fluid. This ratio is called the Reynolds number
es: Número de Reynolds
shear stress
conjunction
When an external force acts on an object, It undergoes deformation. If the direction of the force is parallel to the plane of the object. The deformation will be along that plane. The stress experienced by the object here is shear stress or tangential stress.
Example: Average shear stress can be calculated by taking the ratio of force per unit area
es: Esfuerzo cortante
Turbulent flow
conjunction
type of fluid (gas or liquid) flow in which the fluid undergoes irregular fluctuations, it is too hard to study
Example: When looking at residence time in the holding tube and the safety and quality of the end product, TURBULENT FLOW is better than laminar as there is a smaller distribution of residence time.
