Search Results

The heat flux will be higher at the bottom of the plate since the thickness of the boundary layer which is a measure of thermal resistance is the lowest there.

May you post the assembly?

Heat transfer coefficient is the property in natural/ forced convection and to be derived upon conditions of study. The range of heat transfer coefficient (h) depends on whether it is considered on a flat plate, tubes, ducts etc. and subjected to free (natural) convection or forced convection. In general heat transfer coefficient in natural convection is far less compared to forced convection. In natural convection, the heat is taken away slowly by buoyancy force and in forced convection, the heat is taken away fastly by velocity.

Natural convection in a room can be created by differences in temperature. For instance, it happens when heating a room as warmed air rises due to its lower density, while cooler, denser air sinks. Also, placing a hot object near a cold one can stimulate natural convection.

To calculate the average rate of heat flux from the wall to the room air due to both natural and for...

Sol:- 1.1) Given data, Identify all heat transfer processes and the pathways that contribute to the cooli...

I don’t know if all of the answers here are correct, but at least some are rather inconclusive. The real answer is short and simple. Natural convection is weaker than forced convection because fluid velocity is much lower. “Natural” means that the fluid circulates because of differences of density induced by differences in temperature. This effect is very small; the value depends on temperature difference, length, and volume expansion coefficient of the fluid, but it is normally one or two orders of magnitude lower than the usual velocities in forced convection, say 1 m/s for liquids and 10 m/s for gases. As a consequence, the convection coefficients are much lower.

Given Data: • The width of vertical plate is: w=1m • The height of vertical plate is: y=1.6m • The room temperature is: Tr=20∘C=293K • The temperature of one side of plate is: Tp=80∘C=353K • The emissivity of the plate surface is: ε=0.6 The air always present in the room and it contribute to heat transfer by the natural heat convection. The coefficient of heat transfer of air for natural convection is: ha=100W/m2⋅K The Stefan Boltzmann constant is: σ=5.67×10−8W/m2⋅K4 The expression for area of vertical plate is Ap=wy The expression for rate of heat transfer from the plate by natural convection is Qa=haAp(Tp−Tr) Substitute the value and solve the above expression Qa=hawy(Tp−Tr)=100×1×1.6(353−293)=9600W Thus the rate of heat transfer from the plate by natural convection is 9600W The expression for rate of heat loss from the plate by radiation is Qr=εσApTp4 Substitute the value and solve the above expression Qr=εσwyTp4=0.6×5.67×10−8×1×1.6×(353)4=845.187W Thus the rate of he…

Concepts Natural convection, heat transfer coefficient (h), heat transfer rate (q), Grashof number (Gr), Prandtl number (Pr), Nusselt number (Nu), dimensional analysis, SI and English units Explanation We are asked to calculate the natural convection heat-transfer coefficient and the heat-transfer rate per meter width for an oven wall at Ts​=366.5 K, with ambient temperature T∞​=293 K (assumed room temperature unless otherwise specified). Radiation is neglected. We'll use both Eq. (4.7-4) and the simplified equation for vertical plates. Eq. (4.7-4) for vertical plates: Nu=0.59(Gr⋅Pr)1/4for104

Convective heat transfer pertains only to the fluid medium that is carrying the heat away. The material being cooled does not come into it, since the convective heat transfer equation is based on the surface temperature. For a full equation of cooling (within the bulk of the material) you'd also need to know about thermal diffusion of the material itself.