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Fiat 1.4L CNG performance - Presentation contents

This study examines the performance of the Fiat 1.4L CNG engine through detailed bench testing. It explores two phases: the first with a base engine at a compression ratio of 9.8:1 and the second with new hardware and a enhanced compression ratio of 11:1 using VGT technology. Key findings show torque and power outputs under various load conditions, alongside simulations of turbocharger configurations for optimizing performance. The results indicate that while improvements were observed, limitations were identified due to turbine inlet temperature constraints, impacting overall efficiency.

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Fiat 1.4L CNG performance - Presentation contents

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  1. Fiat 1.4L CNG performance - Presentation contents • Engine tests at bench : 1st phase with base engine • Engine characterization with CR 9.8 (full load + Willans) • Engine improvements : CR = 11:0 + Turbo matching • Engine tests at bench : 2nd phase with new hardware • Engine characterization with CR 11 + VGT (full load + Willans)

  2. Engine tests at bench : 1st phase with base engine • Compression ratio : 9,8:1 • Turbocharger : IHI 150 CV

  3. Engine tests at bench : 1st phase with base engine • Partial load characterisation • Willans lines

  4. Engine tests at bench : 1st phase with base engine • Full load characterisation • Constraints : max temperature inlet turbine = 950 °C • max cylinder pressure (Pcyl max + 3s) = 105 bars Max torque : IFP : 226 N.m @ 2500 rpm CRF : 218 N.M @ 2040 rpm Max power : IFP : 90 kW @ 5000 rpm CRF : 94 kW @ 5000 rpm

  5. Engine improvements : CR = 11:0 + Turbo matching Turbo matching : Simulation of 4 turbocharger configurations : Pressure loss models :

  6. Turbo matching 2000 rpm Compressor IHI RHF3 BRL315 04 (Base TC) Compressor C224(46) 55 Trim 0.46 A/R > 3000 rpm 1 3 2 4 Compressor C224 (44) 60 Trim 0.44 AR (associated with VGT) 4750 rpm Compressor C224(38) 60 Trim 0.38 A/R

  7. Turbo matching VGT turbocharger simulation : Allowed max. BMEP taking into account surge line Target 60 % 80% 30 % ? 100 % 40 % • VGT is the best competitor to improve the full load engine performances. • VGT offers the potential to improve the low speed engine performance, in spite of the surge line of the compressor from 1000 to 1500 rpm • For engine speed higher that 2500 rpm, the VGT turbine also offers an higher efficiency than a fixed geometry turbine with an opened waste gate.

  8. Engine tests at bench : 2nd phase with new hardware • Compression ratio : 11:1 • Turbocharger : VGT Garrett GT1444

  9. Engine tests at bench : 2nd phase with new hardware • Partial load characterisation • Willans lines

  10. Engine tests at bench : 2nd phase with new hardware • Differences observed at partial load could be due to : • New compression ratio • New turbine permeability • New engine parts (piston rings, crankshaft bearings, …)

  11. Engine tests at bench : 2nd phase with new hardware • Full load characterisation : Torque • Constraints : max temperature inlet turbine = 850 °C • max cylinder pressure (Pcyl max + 3s) = 105 bars • Max torque : • IFP CR 9.8:1 : • 226 N.m @ 2500 rpm • IFP CR 11:1 + TGV • 227 N.m @ 2250 rpm • (limited by Tin turb = 850 °C)  Max torque at lower rev

  12. Engine tests at bench : 2nd phase with new hardware • Full load characterisation : Power • Constraints : max temperature inlet turbine = 850 °C • max cylinder pressure (Pcyl max + 3s) = 105 bars • Max power : • IFP CR 9.8:1 : • 90 kW @ 5000 rpm • IFP CR 11:1 + TGV (l=1) • 76 kW @ 4500 rpm !! •  strongly limited by • Tin turb 850 °C, not WOT • IFP CR 11:1 + TGV (l opti) • 92 kW @ 5000 rpm • limited by Tin turb = 850 °C

  13. Engine tests at bench : 2nd phase with new hardware • Full load characterisation : Thermomechanical constraints Turbine inlet temperature Pcyl4 + 3s Performation limitation due to turbine inlet inlet temperature

  14. Engine tests at bench : 2nd phase with new hardware • Full load characterisation : Turbochargers duty zones IHI 150 CV VGT Garrett GT1444 Compressor of Garrett TC presents better efficiency than IHI one In return, surge limit is dramatically reduced

  15. Conclusions • New hardware configuration (VGT + CR 11:0) • offers similar performances regarding maximum torque and power. No improvement was obtained because the lower maximum turbine inlet temperature (850°C vs. 950°C) • reduces maximum torque engine speed (VGT effect) • does not reduce the fuel consumption because the turbine is undersized • GT 1444 compressor works with a better efficiency … • … but the safety margin regarding surge is not sufficient with the GT1444

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