Numerical Analysis on the Oil Pumping Process for Reciprocating Compressors Considering Biphasic Flow

Transcription

1 Nmeical Analysis on the Oil Pmping Pocess fo Recipocating Compessos Consideing Biphasic Flow Diego Sacomoi Reseach Enginee Whilpool S.A. - Embaco Compessos

2 Smmay Embaco Oveview Design to High Efficiency Compessos Oil Spply System fo Recipocating Compessos CFD 3D Simlation with ICEM/CFX Nmeical and Expeimental Reslts Final Remaks

3 Company Pofile Italy Maket and Technological Leade in Hemetic Compessos fo Refigeation; It offes complete cooling soltions in the development of innovative and high pefomance podcts fo the commecial and hosehold efigeation segments; Almost 10 thosand employees woldwide; Mission: "Povide innovative soltions fo a bette qality of life".

4 Wold Pesence United States Italy USA Italy Slovakia China China Mexico Bazil Bazil Compesso Plant Electical Components Office Electonics Fondy

5 The Podcts

6 Design to high efficiency compessos Impovements on the: Manifold Mechanism sppot Electic moto High Efficiency Mechanical Powe Losses Lbication Asse: Low noise Qality and Reliability It is vey impotant to eliability and high efficiency in efigeation compessos. Low costs

7 Oil Spply System fo Recipocating Compessos The lbicant oil is speed p by the centifgal foce ntil the seconday beaing, then it is caied mechanically by the lbication goove. Oil hole - main beaing Oil hole - seconday beaing Otlet fo the piston Oil hole eccentic beaing Cankcase Lbication goove... and abot the pmping head? Cankshaft Oil pmp Inlet oil fom case

8 Oil Spply System fo Recipocating Compessos Modeling the simplified poblem... a g p ) ( 1 k a e a e a gk k z p e p e p z 0 a z 0 a a in igid body motion: dz z p d p dp z z z g p p g h z 1 g R h h whee, 0 1 R g R h z

9 Oil Spply System fo Recipocating Compessos and intodcing a bottom hole... c c A c c d da Q P z g z p z t 1 1 The open aea of the pmp s oifice is nable to sppot the pmping pesse. So, the oil flows down thogh the hole. The pesse dop in the oifice can be detemined by taking into accont of inflow and otflow thogh the hole. (Itoh, 199)

10 Oil Spply System fo Recipocating Compessos The main vaiables at mechanical kit that inflences in the pmping head ae: Inlet and otlet diamete; Blade pesence Oil viscosity; Shaft speed; Lbication goove and oifices Oil pmp imesion; Geometic deviations Opeation constaints Pmp constaints Assembly constaints Ex.: concenticity between pmp and otation axis Shaft constaints

11 CFD 3D Simlation with ICEM/CFX Meshing in the ICEM: Easie to geneate the inteface domains and contol the qality mesh. Tetaedic mesh + pisms (nea the wall to incease the esoltion).

12 CFD 3D Simlation with ICEM/CFX Some options to inpt fo the CFX analysis: Tansient analysis Biphasic flow (oil based wate + ai) Time simlation s (step 0.01s) Boyancy model Homogeneos model fo mltiphase and heat tansfe Lamina flow Imesion 10mm Angla speed 3000pm

13 CFD 3D Simlation with ICEM/CFX and to aise the oil 1. To otate the Pmp s walls The geomety mst be axisymmetic It does not sppot eccentic pmp. To otate the inside domain 3. To defome the mesh (not analyzed)

14 Otlet Flow CFD 3D Simlation with ICEM/CFX Mesh evalation: Nmbe of elements

15 CFD 3D Simlation with ICEM/CFX Tansient flow behavio Initial time Time step 5 Time step 50 Link to movie Time step 00

16 Nmeical Reslts Dives fo the simlation Evalate the oil flow sensivity elative to the pmp vaiables: Otlet diamete Inlet diamete Blade pesence

17 Expeimental Test Bench Test: The cankshaft otation is contolled by an invete. The oil flow is evalated by infaed sensos. It calclates the time to the oil speed p in a known volme.

18 Otlet Flow Nmeical Reslts: Blade evalation: 1, Speficial velocity Z 1,0 0,8 0,6 0,4 0, 0,0 it inceases the momentm fo the flid. Withot Blade With Blade Time step Speficial velocity Z

19 Otlet Flow Nmeical Reslts: Otlet flow: 3 pmp models: 1,6 1,4 This pmp is able to povide good eslts, bt is had to asse the concenticity between the bottom end and the otation axis in the manfacting pocess. 1, 1,0 0,8 0,6 0,4 0, 0,0 REFERENCE Pmp Ref Pototype Concentic Pmp Pototype Eccentic Pmp Time step

20 Otlet Flow Otlet Flow Nmeical Reslts: Otlet diamete evalation: 1, 1,1 1,0 0,9 Δ~10% Assembly constaint: to define toleances fo the otlet diamete 0,8 0,7 0,6 1 0,5 0,4 0,3 0, Otlet -0.4mm Otlet REF 0,95 0,9 Expeimental eslts Δ~10% 0,1 0, Time step Otlet +0.4mm Above ppe vale (Otlet +0.4mm) the otflow is insensitive to incease the otlet diamete. 0,85 0,8 Otlet REF Otlet - 0.4mm Otlet diamete (mm)

21 Otlet Flow Nmeical Reslts: Inlet diamete evalation: 1,4 1,3 1, 1,1 1,0 0,9 0,8 0,7 0,6 0,5 0,4 0,3 0, 0,1 0,0 Inlet -0.5mm Inlet REF Inlet +0.5mm Inlet +1.0mm Inlet +1.5mm The elation between the inlet diamete and the otlet flow is not linea: - if the inlet is smalle, it consticts the flow; - if it is geate, the pmping pesse dops de the open aea. An optimm point mst be find. Time step

22 Expeimental Reslts: Flow x Inlet x Otlet The statistical analysis of the expeimental eslts shows the simila diection fom nmeical simlation.

23 Conclding emaks The sensitivity analysis fo the oil spply pocess has been pefomed. The CFX/ICEM poven to be effective fo this kind of application. It is a powefl tool since it allows time and costs edction looking fo the geometic vaiables and toleances in the pototype evalation. The CFX still povide othes analysis on the flow behavio fo this application like: se of the tblence models, compaison between the diffeent models to speed p the flow (domain motion, otation wall, defomed mesh).

24 Conclding emaks The total time simlation cold be optimized if the meshing was made in the Wokbench. Next steps: Evalate the oil flow consideing also the cankshaft s constaints. Wok to optimize the mesh (simlation time).

25 Thank yo fo the attention! Diego Sacomoi