Thermo 2

Question 1

What is the Clausius statement?

Answer 1

‘It is impossible to construct a device which, operating in a cycle, will produce no other effect than the transfer of heat from a cooler to a warmer body’

Question 2

What does the Clausius statement mean?

Answer 2

-Heat transfer can only occur spontaneously in the direction of temp decrease
-E.g. can’t construct a refrigerator that operates without a work input

Question 3

What are the 8 state functions

Answer 3

-Enthalpy, H
-Temp, T
-Pressure, P
-Entropy, S
-Internal energy, U
-Volume, V
-Helmholtz energy, A
-Gibbs energy, G

Question 4

Which state functions are measurable?

Answer 4

Pressure, volume and temp.

Therefore relations we use to describe other state functions can be equated with ideal gas laws

Question 5

What is a shear thinning fluid

Answer 5

One where the viscosity of the fluid decreases (runnier) as the shear rate is increased

Question 6

What is a shear thickening fluid

Answer 6

-One where the viscosity of the fluid increases (flows less well) as the shear rate is increased
-Fairly uncommon

Question 7

What is a yield stress material, and an example

Answer 7

-One that requires a critical stress to be exceeded before a continuous deformation (flow) can be achieved
-Example: Bingham plastic

Question 8

Turbulent flow is typically good for mixing but what are potential disadvantages?

Answer 8

-Cavitation
-Damage
-High pressure drop

Question 9

What 3 mechanisms are used if laminar flow is used for mixing

Answer 9

-Laminar shear
-Elongation/extension
-Distributive mixing

Question 10

How does uniaxial extension work, e.g. for extension in the x direction

Answer 10

For uniaxial extension in the x direction, compression equal to half the strain rate of the x will occur in the y and z direction
-Difficult to achieve as a material cannot be infinitely extended

Question 11

How does planar extension work, e.g. for extension in the x-direction

Answer 11

For elongation in the x direction there will be compression in the y direction, at the same rate, and no deformation along the z axis

Question 12

What is distributive mixing?

Answer 12

Blends a material through spatial redistribution

Question 13

What is dispersive mixing?

Answer 13

Breaking down a material into increasingly smaller pieces

Question 14

Mixing is independent of?

Answer 14

-Fluid flow rate
-Fluid rheology