Quiz Six Flashcards
What are granular materials?
Granular materials are a mixture of particles and air
What are powders?
Powders are finely found granular materials (25-30 um)
How are powders a two faced matrix?
Powders are a two faced matrix because they contain both solid material and air - there are air pockets embedded within the solid particles making up for some of the volume
What is bulk density? How is it calculated?
Bulk density is the ratio of overall mass of material divided by the volume occupied by the material - it is calculated by adding the density of particles times the volume fraction of particles by the density of air times the volume fraction of air
What is particle density? How is it calculated?
Particle density is the mass and volume ratio of an individual particle - it is calculated by multiplying the particle solid density by the volume fraction of particles plus the density of air multiplied by the volume fraction of air
What is the relationship between particle and bulk density?
Particle density will always be greater than or equal to bulk density
What is porosity? How is it calculated?
Porosity (psi) is the ratio of air volume to powder volume - it is calculated by 1 - bulk density divided by solid particle density
What is the advantage of having a bimodal size distribution of particles?
A bimodal size distribution means there will be two mean sizes of particles - this allows the product to be packed more tightly together
How do you calculate the angle of internal friction?
To calculate the angle of internal friction divide shear stress by the normal force
What is conduction? When is it used?
Conduction is heat transfer within solids by molecular movement - it is used with higher viscosity products (slower heating)
What is convection? When is it used?
Convection is heat transfer in liquids by movement of molecules due to density differences - it is used with low viscosity products (faster heating)
What is radiation?
Radiation is the transfer of heat by electromagnetic waves
What is specific heat? How is it calculated?
Specific heat is a measure of energy needed to raise the product temperature - it is the quantity of heat gained or lost by a unit mass to accomplish a degree change in temperature without a change in state- it is calculated by dividing the quantity of heat by the mass times the change in temperature - units are kJ/kg*K
What is thermal conductivity? What are the units?
Thermal conductivity measures how well energy is transferred through a material - the units are watts/mass times degrees celsius
