1In 2003 Frick Is Celebrating 150 Years in Manufacturing and 120 Years in Refrigeration 2Frick has Produced over 60,000 Screw Compressors since the First RWB-II was introduced in 19823Screw Compressor Basic Geometry4Construction Male and Female Rotors Mounted on Radial and Axial Bearings Fitted in close tolerance intersecting bores.5Suction process6Maximum Suction Volume TrappedVsVs7Compression8Continuation of Compression9Beginning of DischargeVd101112End of Discharge13Axial Discharge Port14Vi(Volume Ratio)Vs (Volume of gasat suction)VD (Volume of gas at discharge) =15Volume Ratio All Frick screws built since 1981 incorporate VolumizerTM Variable Volume Ratio control, to minimize power consumption due to over and under compression. This is effective at full and part load.16Volume Ratio Low ViSLIDE VALVESUCTION OPENINGRECIRCULATION SLOTDISCHARGE OPENING17Volume Ratio Hi ViSLIDE VALVESUCTION OPENINGRECIRCULATION SLOTDISCHARGE OPENING18192021Parting LineMoveable Slide Stop2223Frick VolumizerTM variable volume ratio control saves power automatically as conditions change24Capacity Control All Frick screws offer precise and efficient capacity control by use of a slide valve and slide stop controlling in concert together.25Slide Valve UnloadingSLIDE VALVESUCTION OPENINGRECIRCULATION SLOTDISCHARGE OPENING26How Slide Valves Improve Part Load Volume Ratio 27Capacity Control Methods-2Recirculation PassageSlide Valve Regulating Capacity and Discharge Port Location Moveable Slide Stop Regulating Volume Ratio28Slide ValveSlide StopSV PistonSS Piston29Vi is controlled by the Vi is controlled by the QuantumQuantumTMTM , an advanced , an advanced Pentium based microprocessor controlPentium based microprocessor control30All Frick Screws use 100% Anti- Friction Bearings313233Cylindrical Roller Bearing34Anti-Friction Bearings Consume Less Frictional HorsepowerApproximately 11 HP on a 300 HP application35Anti-friction Bearings allow tighter rotor to rotor clearance for less gas leakage and reduced power consumption.36Oil Reservoir37Refrigerant Gas PressureOilOil absorbs gas when pressurizedPressure drop causes absorbed gas to make foam38Oil CoolerRefrigerant Gas PressureOilJournal BearingFilterRefrigerant Forms Bubbles in the Oil as it passes Through the Oil System due to Pressure Drop 39Oil CoolerRefrigerant Gas PressureOil Oil PumpJournal BearingA Journal Bearing Design Requires a Full Time Oil Pump to Keep the Oil above the Separator Pressure Level and Avoid Bubbles in the Bearing40Oil CoolerRefrigerant Gas PressureOilFilterAnti-friction Bearings are Happy to be Lubricated with Oil Foam. Oil Pump Generally Not NeededSaves the cost of the pump Maintenance of the pump Horsepower of the pump41Failure Mode of Anti-Friction Bearings42Bearing Flaw43Early failure detection by vibration analysis44A minor scratch doesnt mean imminent failure - it takes months to get to this level from beginnings of fatigue45This was still a cheap rebuild - no major rotor or housing damage12 gs spike energy46BadGoodEasier to see problem in gs47Failure Detection Early failure detection of anti- friction bearings is easy enough that there is no reason to perform teardown inspection if analysis is done correctly. Not many people understand how to interpret vibration data accurately. Frick provides training, guidelines and in-house support and specialized monitoring equipment.48Frick Lab Facilities Frick Screw test gas loops 2000 HP N2 loop 800 HP variable speed N2 loop 600 HP variable speed NH3 loop 600 HP R-134a loop 150 HP R-22 loop 150 HP R-134a loop 600 HP NH3 stand for noise tests. Misc. small test rigs. 4950Single vs. Twin Screw Twin screws are more efficient and more durable than singles. Stiffer rotors dont deflect under load. Not as sensitive to loss of lubrication as single screws. No plastics to absorb refrigerant and swell or shrink Rolling contact between screws vs. sliding contact, with longer leakage path from high side to low side. 51Single vs. Twin Screw Flow area leaving discharge ports in single screw and in part load bypass ports is very small, limiting the compressor size to no more than 250 TR at chiller conditions. Star wheel bearings are in the way. Gives poor part load performance. Twin screws can survive temporary loss of lubricant, single cannot.52Single vs. Twin Screw Single screws have lower radial bearing loads but still have high thrust and loads on the stars. Higher theoretical loads in twins dont matter as long as the bearings are big enough to last. Backspin breaks star wheels Single screws have Many complex small parts associated with the slide control.53 Frick/York has a single screw license and for a while developed both machines. Ultimately the performance of the single screw could not compete with the twin and abandoned the single screw development.Single vs. Twin Screw