1.-8. (canceled)
9. A method of extruding material comprising:
providing an extruder comprising:
a housing having at least two cylindrical housing bores, each housing bore having an axis disposed parallel to the other axis and the first and second axes separated by a distance a;
at least a first screw shaft and a second screw shaft being disposed in the first and second housing bores, the first and second screw shaft being provided with a first and second screw respectively, the first and second screw each having an extruder diameter D and a screw root diameter d, the first and second screw shaft each having a volumetric ratio of at least 1.4, wherein the volumetric ratio is defined by the extruder diameter D divided by the screw root diameter d;
at least two inlet hoppers being provided in the vicinity of the housing bores and opening into said housing bore with at least one of the inlet hoppers having a side inlet that opens into the housing bore;
feeding material to be processed through the at least two inlet hoppers into the housing bores;
conveying the material through the extruder length from the inlet hoppers to the extruder outlet;
driving each of said first and second screw shafts at a speed of at least 1000 rpm and at a torque density of at least 8.5 Nmcm3;
the torque density defined by the shaft torque at each first and second shaft divided by the third power of the distance a between the first and second axes.
10. A method as claimed in claim 9 wherein material is fed into the extruder from at least one side hopper.
11. A method as claimed in claim 10 wherein the material is force fed from the side hopper into the extruder.
12. A method as claimed in claim 9 wherein the extruder is operated at a torque density of at least 17 Nmcm3.
13. A method of extruding material comprising:
providing an extruder comprising:
a housing having at least two cylindrical housing bores, each housing bore having an axis disposed parallel to the other axis and the first and second axes separated by a distance a;
at least a first screw shaft and a second screw shaft being disposed in the first and second housing bores, the first and second screw shaft being provided with a first and second screw respectively, each screw including at least one element, the first and second screw each having an extruder diameter D and a screw root diameter d, the first and second screw shaft each having a volumetric ratio of at least 1.4, wherein the volumetric ratio is defined by the extruder diameter D divided by the screw root diameter d;
a first intake element coupled to the first shaft and including a first flight, a second intake element coupled to the second shaft adjacent the first intake element and including a second flight, wherein the first flight and the second flight are adapted to co-operatively create a partial vacuum that acts as a positive displacement pump to convey material when the first intake element and the second intake element are rotated in the same direction;
at least two inlet hoppers being provided in the vicinity of the housing bores and opening into said housing bore with at least one of the inlet hoppers having a side inlet that opens into the housing bore;
feeding material to be processed through the at least two inlet hoppers into the housing bores;
conveying the material through the extruder length from the inlet hoppers to the extruder outlet;
driving each of said first and second screw shafts at a speed of at least 1000 rpm and at a torque density of at least 8.5 Nmcm3;
the torque density defined by the shaft torque at each first and second shaft divided by the third power of the distance a between the first and second axes.
14. A method as claimed in claim 13 wherein the first flight and the second flight define an undercut.
15. A method as claimed in claim 14 wherein the undercut is less than 85 degrees.
16. A method as claimed in claim 14 wherein the extruder is operated at a torque density of at least 17 Nmcm3.
17. An extruder comprising:
a housing having at least two cylindrical housing bores, each housing bore having an axis disposed parallel to the other axis and the first and second axes separated by a distance a;
at least a first screw shaft and a second screw shaft being disposed in the first and second housing bores;
the first and second screw shaft being provided with a first and second screw respectively;
the first and second screw each having an extruder diameter D and a screw root diameter d;
the first and second screw shaft each having a volumetric ratio of at least 1.4, wherein the volumetric ratio is defined by the extruder diameter D divided by the screw root diameter d; and
at least two inlet hoppers being provided in the vicinity of the housing bores and opening into said housing bore with at least one of the inlet hoppers having a side inlet that opens into the housing bore.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A nanofluid composition comprising carbon nanoparticles, metal oxide nanoparticles having a pHpzc, and at least one surfactant having a net negative charge in a hydrophilic thermal transfer fluid, wherein the composition has a pH below the pHpzc of the metal oxide nanoparticles.
2. The nanofluid composition of claim 1, wherein the carbon nanoparticles are selected from the group consisting of diamond nanoparticles, graphite nanoparticles, fullerenes, carbon nanotubes, and carbon fibers.
3. The nanofluid composition of claim 1, wherein the hydrophilic thermal transfer fluid is selected from the group consisting of water, alkyl alcohols, alkylene glycols, and combinations thereof.
4. The nanofluid composition of claim 3, wherein the alkylene glycol is ethylene glycol or diethylene glycol.
5. The nanofluid composition of claim 1, wherein the carbon nanoparticles are carbon nanotubes.
6. The nanofluid composition of claim 1, wherein the carbon nanoparticles are single wall nanotubes (SWNTs).
7. The nanofluid composition of claim 1, wherein the carbon nanoparticles are multi-wall nanotubes (MWNTs).
8. The nanofluid composition of claim 1, wherein the metal oxide nanoparticle comprises a metal oxide selected from the group consisting of MgO, CuO and Al2O3.
9. The nanofluid composition of claim 1, wherein the surfactant is selected from the group consisting of sodium dodecylbenzenesulfonate (SDBS) and sodium dodecyl sulfate (SDS).
10. The nanofluid composition of claim 1, wherein the carbon nanotube is a SWNT, the metal oxide nanoparticle comprises MgO, CuO or Al2O3, at least one surfactant is SDS or SDBS, and the composition has a pH of between 7 and 9.
11. A method for making a nanofluid composition comprising the steps of:
a) mixing together carbon nanoparticles, metal oxide nanoparticles having a pHpzc, and at least one surfactant having a net negative charge into a hydrophilic thermal transfer fluid; and
b) adjusting the pH of the composition below the pHpzc of the metal oxide nanoparticles.