Christian Ivan Birrueta Vargas (7°A)

10 English and heat transfer module. terms

This glossary serves to understand some of the basic concepts of heat transfer, which were rescued from a summary reading on the subject. The main topic of this glossary is convection which can be both natural and forced due to the speed of a fluid, the main terms to understand this form of heat transfer are detailed below.

Convection heat transfer coefficient: Noun.; It is the rate of heat transfer between a solid surface and a fluid per unit area per unit temperature difference, they are determined differently for natural or forced convection.; Example: The CONVECTION HEAT TRANSFER COEFFICIENT can be determined from the Nusselt relations.; en: Coeficiente de transferencia de calor por convección.
Critical Reynold’s number: Noun.; The critical Reynolds number determines if a flow is laminar or turbulent, for example for Re<5 ×10^5 the flow is laminar, if the number is greater the flow would be turbulent.; Example: Generally, a fluid that travels through a pipe has a Reynols number lower than the CRITICAL REYNOLD'S NUMBER.; en: Número crítico de Reynolds.
Friction Coefficient: Noun.; It links the opposition to sliding offered by the surfaces of two bodies in contact according to the intensity of the mutual support they experience. It is a dimensionless coefficient.; Example: Ice on a polished steel sheet has a low COEFFICIENT OF FRICTION.; en: Coeficiente de fricción.
Kinematic viscosity: Noun.; Is a measure of a fluid's internal resistance to flow under gravitational forces. It is determined by measuring the time in seconds, required for a fixed volume of fluid to flow a known distance by gravity through a capillary within a calibrated viscometer at a closely controlled temperature.; Example: The KINEMATIC VISCOSITY η decreases with great intensity in those liquids with an increasing temperature.; en: Viscosidad cinemática.
Laminar flow.: Noun.; Laminar flow or laminar current is called the movement of a fluid when it is ordered, stratified or smooth. In laminar flow, the fluid moves in parallel sheets without intermingling and each fluid particle follows a smooth path, called a streamline.; Example: LAMINAR FLOW is typical of fluids at low velocities or high viscosities.; en: Flujo laminar.
Nusselt number: Noun.; It is a dimensionless number that measures the increase in heat transfer from a surface through which a fluid flows (heat transfer by convection) compared to the heat transfer if it occurred only by conduction.; Example: Unlike other dimensionless numbers, the NUSSELT NUMBER is used for both natural and forced convection.; en: Número de Nusselt.
Prandtl number: Noun.; Is a dimensionless number proportional to the quotient between the diffusion rate of the amount of moment (viscosity) and the thermal diffusivity.; Example: In air the PRANDTL NUMBER depends on the temperature.; en: Número de prandtl
Reynold number: Noun.; The Reynolds number (Re) is a dimensionless number used in fluid mechanics, reactor design, and transport phenomena to characterize the motion of a fluid. Its value indicates whether the flow follows a laminar or turbulent pattern.; Example: A high NUMBER OF REYNOLDS indicates that the fluid is turbulent, or a combination of laminar and turbulent.; en: Número de Reynolds.
Shear stress: Noun.; Is a force tending to cause deformation of a material by slippage along a plane or planes parallel to the imposed stress. The resultant shear is of great importance in nature, being intimately related to the downslope movement of earth materials and to earthquakes.; Example: SHEAR STRESS may occur in solids or liquids; in the latter it is related to fluid viscosity.; en: Esfuerzo cortante.
Turbulent flow: Noun.; Is one in which there are fluctuations in the flow all the time and the particles invade the path of the adjacent particles, mixing and moving in a random way.; Example: The flow of water in rivers or the movement of air near the earth's surface are typical examples of TURBULENT FLOW.; en: Flujo turbulento.