FIELD

This disclosure relates to pumping low viscosity, non-lubricating fluids, and more particularly to a scroll technology based pump for refrigerants such as liquid fluorocarbons and similar fluids for a variety of heat transfer, refrigeration, and space conditioning applications.

BACKGROUND

Low viscosity, non-lubricating liquids, such as fluorocarbon refrigerants, are notoriously difficult to pump, especially when the application requires the pump to significantly increase the liquid pressure with the liquid at the pump inlet being minimally subcooled (i.e., in pump industry terminology, have a minimal net positive suction head, typically abbreviated as NPSH) and that the liquid being pumped not be mixed with or contaminated by a separate lubricant. The challenges of pumping in this regime are well known. For example, the common fluorocarbon refrigerants and heat transfer fluids are generally low in liquid viscosity and offer no boundary lubrication type lubricity making mechanical design of a pump to handle these fluids challenging with respect to both mechanical friction losses and the wear life of rotating shafts, bearings, and pump elements. In addition, many potential applications of refrigerant pumps require that the liquid be minimally subcooled so there is minimal net positive suction head. Many pump types are highly susceptible to cavitation under these conditions, leading to rough operation, poor performance, erosion, and ultimate destruction of pump elements, especially centrifugal pump impellers.

Nevertheless, there are several potential applications for a liquid pump of this type. For example, in two-phase heat transfer loops, a liquid refrigerant is pumped to one or more heat exchangers to cool various components. A portion of the liquid evaporates in each heat exchanger, with the heat of vaporization of the evaporated liquid absorbing the cooling load from that heat exchanger. Significantly more heat can be carried in relationship to the mass flow rate of heat transfer fluid and at constant temperature. Before returning to the pump, the two phases (vapor and the remaining unevaporated liquid) pass through a condenser, typically returning to the pump as a liquid with minimal subcooling. The amount of pressure rise needed to force the liquid flow around the loop depends of the overall size and length of the loop and the type of flow control devices that are used.

With the growth of the internet and information storage, the energy consumption for cooling data centers has become significant, on a par with the electrical energy consumption of the servers, themselves. The so-called liquid refrigerant economizer cycle can save significant amounts of cooling energy, especially in cooler climates. The liquid refrigerant economizer cycle is implemented by adding a liquid refrigerant pump to the typical data center cooling equipment. When the outdoor temperature is cool enough, typically below 45 degrees Fahrenheit (° F.), refrigerant vapor from the evaporators bypasses the refrigerant compressors and condenses directly in the condenser. The condensed refrigerant, again typically with minimal subcooling, must be pumped back to the evaporators with enough pressure to force the refrigerant though the expansion devices.

Another potential application is for pumping liquid refrigerant in a supermarket refrigeration system with fully floating head pressure, as low as the outdoor ambient temperature will allow. With extremely low condensing temperature and pressure, a liquid pump is needed to raise the liquid pressure high enough to pass through normally sized expansion valves. With this arrangement, a Watt of pump power will save on the order of 25 Watts of compressor power, compared to conventional head pressure control that does not allow the condensing temperature to fall below 75° F.

As such, there is a need for new pumps or pumping systems suitable for addressing the foregoing challenges and uses.

SUMMARY

The following summary is provided to facilitate an understanding of some of the innovative features unique to the present disclosure and is not intended to be a full description. A full appreciation of the various aspects of the disclosure can be gained by taking the entire specification, claims, drawings, and abstract as a whole.

In a first aspect A1, a pump includes an inlet, an outlet, and a scroll pumping element. The scroll pumping element includes a fixed scroll component having one or more fixed scrolls and orbiting scroll component having one or more orbiting scrolls for fluid pumping where the fixed scroll component and the orbiting scroll component are arranged so as to be capable of providing pressurized fluid to a thrust bearing and prevent contact between the fixed scroll component and the orbiting scrolls component.

A second aspect A2 includes the pump of the first aspect A1 where a wrap length of the one or more orbiting scrolls is 0.75 wraps to 1.25 wraps long, and a wrap length of the one or more fixed scrolls is 1.75 wraps to 2.25 wraps long.

A third aspect A3 includes the pump of the first aspect A1 where a wrap length of the one or more orbiting scrolls is one wrap long and a wrap length of the one or more fixed scrolls is two wraps long.

A fourth aspect A4 includes the pump of the first aspect A1 and further includes an Oldham coupling associated with the orbiting scroll component.

A fifth aspect A5 includes the pump of the fourth aspect A4 wherein the Oldham coupling includes a wear resistant coating

A sixth aspect A6 includes the pump of the fifth aspect wherein the wear resistant coating is or includes hard anodized aluminum.

A seventh aspect A7 includes the pump of any of the first-sixth aspects A1-A6 further including an orbital drive mechanism in fluid communication with the outlet, wherein the orbital drive mechanism includes a drive shaft, two drive shaft bearings that support the drive shaft, and a radially compliant crank mechanism associated with the drive shaft.

An eighth aspect A8 includes the pump of the seventh aspect A7 wherein the drive shaft bearings are radial ball bearings with ceramic balls.

An ninth aspect A9 includes the pump of the seventh aspect A7 further including an orbiting scroll bearing between the radially compliant crank mechanism and the orbiting scroll component.

A tenth aspect A10 includes the pump of the ninth aspect A9 wherein the orbital scroll bearing is a radial ball bearing with ceramic balls.

An eleventh aspect A11 includes the pump of any of the first-tenth aspects A1-A10 and further includes an electric drive motor mechanically coupled to the orbital drive mechanism.

A twelfth aspect A12 includes the pump of the eleventh aspect A11 where the electric drive motor is hermetically enclosed within a fluid space.

A thirteenth aspect A13 includes the pump of the eleventh aspect A11 and further includes a second fluid outlet allowing fluid flow through the electric drive motor.

A fourteenth aspect A14 includes the pump of any of the first to the thirteenth aspects A1-A13 where the orbital drive mechanism includes a drive shaft and the electric drive motor is mechanically coupled to the drive shaft and is located outside a pressure-tight housing.

A fifteenth aspect A15 includes the pump of any of the first-fourteenth aspects A1-A14 where the fixed scroll component and the orbiting scroll component each have wear-resistant surfaces.

A sixteenth aspect A16 includes the pump of the fifteenth aspect A15 where the wear-resistant surfaces comprise or consist of hard anodized aluminum.

