Thermo Lecture 2

Thermo Lecture 2 - Setting A rectangular slab of thickness x and with an area A The front side of the slab is at a temperature T the back side has

Info iconThis preview shows pages 1–5. Sign up to view the full content.

View Full Document Right Arrow Icon
the area of the slab, the temperature difference, Δ T , between the back and the front; and inversely proportional to Setting: A rectangular slab of thickness Δ x and with an area A . The front side of the slab is at a temperature T ; the back side has a somewhat different temperature, T+ Δ T . We are trying to calculate the heat- flow rate, the amount of heat flowing through the slab per unit time, H = Δ Q/ Δ t . the thickness of the slab, Δ x . H should also somehow depend on properties of the material of the slabE We expect H to be proportional to
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Bringing all the parts together: H = Δ Q/ Δ t – heat-flow rate is measured in Joules/second, J/s , or Watts, W . Thermal conductivity, k , is measured in W/(m K) . x T kA H Δ Δ = The coefficient k reflects specific properties of the material of the slab and is called thermal conductivity
Background image of page 2
Thermal conductivities of different materials. Best heat conductor – Copper; use it when you build a heat sink, as a material for pipes in your cooling system, a radiator. Worst heat conductors are the best insulating materials – air, fiberglass (layers in the walls of houses in cold regions), styrofoam (cups for your hot coffee).
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Heat-flow rate equation Continuing the analogy: electric resistance, R , is analogous to ) /( kA x T x T kA H Δ Δ = Δ Δ = Is similar to the Ohm’s law: R V I = The current, I = Δ q/ Δ t , amount of charge per unit time, is analogous to the heat-flow rate, H = Δ Q/ Δ t. The voltage,
Background image of page 4
Image of page 5
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 02/05/2011 for the course BILD 2 taught by Professor Schroeder during the Spring '08 term at UCSD.

Page1 / 23

Thermo Lecture 2 - Setting A rectangular slab of thickness x and with an area A The front side of the slab is at a temperature T the back side has

This preview shows document pages 1 - 5. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online