Experimental Investigation of Waste Heat Recovery Using an ORC for Heavy Duty Trucks

Transcription

1 Experimental Investigation of Waste Heat Recovery Using an ORC for Heavy Duty Trucks M. Hombsch a, K. Shariatmadar a, D. Maes b, P. Garsoux c a Dana Belgium NV, b Flanders Make VZW, c Bosal Emissions Control Systems NV 4 th Engine ORC Consortium Workshop November 15-17, Detroit, Michigan

2 Design methodology and system optimization tool Flanders Make Waste Heat Quality High Fuel Energy 100% Waste Heat Quality Low ORC design challenges 2 Evaporator ( heat source) Engine heat sources Brake Power 42% 1 Pum p 3 Expander 4 Condenser ( heat sink) Working fluids Water Ethanol Butane Refrigerant 8% Friction / Misc. Losses 24% Heat Transfer 26% Exhaust Engine Cooling Energy C EGR Cooling Charge Air Cooling C C Tailpipe C

3 Design methodology and system optimization tool Use case specification Heat sources (averaged) Exhaust kg/s, 354 C EGR kg/s, 520 C Heat sink (averaged) Cooling water 1.5 kg/s, 60 C EGR only Exhaust only EGR first Topological variations Six evaporator configurations Recuperator not useful EGR replacement (cost saving from existing cooler) Exhaust first EGR split Parallel

4 Design methodology and system optimization tool Optimization Changes components size and thermal cycle Constrained nonlinear programming Exhaustive search over fluids and topologies Maximize expander power Minimize cost / net power 403 days*. 225 days*.. *assuming 11 hour driving per day

5 Design methodology and system optimization tool Dynamic model in Amesim 2 Evaporator ( heat source) 2 Evaporator ( heat source) 1 Pum p 3 Expander 2 Evaporator ( heat source) 1 Pum p 3 Expander 2 Evaporator 1 Pum ( heat p source) 3 Expander 4 Condenser ( heat sink) 1 Pum p 3 Expander 4 Condenser ( heat sink) 4 Condenser ( heat sink) 4 Condenser ( heat sink)

6 Design methodology and system optimization tool Control Design 2 Evaporator ( heat source) 1 Pum p 3 Expander 4 Condenser ( heat sink)

7 Design methodology and system optimization tool Control Design - Control of evaporator pressure PI + feedforward + decoupling simplest to implement Model based control better constraint handling Tim e in seconds Tim e in seconds

8 Heat exchanger development Bosal Non-dimensional evaporator sizing NTU method (Number of Tranfer Units) Non dimensional numbers, NTU = f r cp, C r, St, Ja 1, ΔT sh ΔT sc, Heat capacity ratio r cp, heat cap. rate ratio C r, Stanton number St Inverse Jacob number Ja 1 (phase change) Ratio of superheating to subcooling ΔT sh ΔT sc No working fluid hard coded in calculations

9 Heat exchanger development Bosal Evaporator size optimization for HD trucks Target: minimum pay-back for total WHR system Inputs Tool developed by Flanders Make Bosal evaporator model Bosal cost model European operating conditions Assumptions Exhaust & EGR evaporators Working fluid: Alcohol based Volumetric expander... Evaporator size minimizing /W

10 Amplification Temperature Heat exchanger development Bosal Power Power Stability of evaporation process Slope of -2 (-20dB/decade), indicating higher frequency massflow oscillations do not affect the outlet temperature significantly Raw signal, Temperature oscillation Water Massflow oscillation dmair Time [s] Transfer function Frequency [Hz] Air Massflow oscillation dmair Frequency [Hz] Frequency [Hz]

11 Heat exchanger development Bosal Heat exchanger performance More than 50 sensors (T, p,ṁ) Heat transfer validation in 2-phase flow Set of operating points Sequenced perturbations

12 Flow validation Voxdale CFD validation Pipe bundle replaced with porous blocks Heat exchange inside blocks Nonlinear pressure drop in X and Y direction Wall temperature given as boundary condition Results Flow uniformity Bypass duct optimization HEX core Bypass info@voxdale.be

13 Heat exchanger development Bosal Hardware built: Evaporator Modular design, different working fluids possible High Pressure operation (60 bar) Proven in-field operation To be integrated in Euro VI muffler Add-on with bypass Evaporator Fluid Bypass Gas Euro VI truck muffler WHR add-on

14 Test bench and experimental results Coolant tank

15 Test bench and experimental results Prototypes: Bosal evaporators Exoès expander Tube & shell heat exchanger double-acting swashplate piston expander

16 Temperature T [ C] Test bench and experimental results Temperature T [ F] Experimental results Power P transferred to the cycle fluid [kw] 2 Evaporator ( heat source) Experiment Pum p 3 Expander Condenser ( heat sink) ,164 1,364 Cycle fluid enthalpy h [kj/kg] 32

17 Raw thermal efficiency Test bench and experimental results Raw output power [kw] Fuel savings 12% 10% Thermal efficiency Maximum Power tested (Conservative assumption) Net fuel savings 5% 4% Conservative Maximum Power assumption 8% 8 3% 6% 6 4% 4 2% 2% Engine back pressure, Pump consumption 2 1% Includes: - Engine back pressure loss - Pump consumption 0% Waste heat exploited [kw] 0% Equivalent shaft power [kw]

18 Test bench and experimental results Sankey diagram for highway cruise Coolant: 29% Coolant: 44% Ambient: 53% Fuel: 100% Exhaust manifold: 29% Brake power: 45% Turbine 17% EGR: 12% 1% Exhaust 12% Charge air 5% 11% 2% 6% 6% 3% WHR: 15% 17% 2% WHR gain, 11% from WHR input 4% from brake power Brake power + WHR: 47%

19 Test bench and experimental results Drive cycle analysis: GEM model 340 kw (455 hp) model year 2018 engine, 6x4 configuration Applied fuel usage weighting to time spent in given power Weighted average of three drive cycles: Urban 55 mph with slopes 65 mph with slopes

20 Test bench and experimental results Drive cycle analysis: average fuel savings Mean fuel savings 3.5%

21 Test bench and experimental results Yearly savings, US sleeper cab 190,200 km year $ l 3.5% l 100km 118,200 miles, first three years, sleeper cab* year 7.06 mpg, Model Year 2018 GEM simulation 3.94 $ gal EIA 2025 retail +10.5% local tax WHR system fuel econemy improvement -$ maintenance = $ 2200 Yearly savings Payback time ca. 2 years Today 2.65 $/gal+28 local tax = 2.93 $/gal ,56 $/gal % local tax = 3.94 $/gal

22 Conclusions Design methodology tool developed for ORC WHR Pre-design tool for selection and size of components Optimizing total cost of ownership Steady-state design with dynamic evaluation Introduction of possible control strategies Hardware ORC Test bench running on Diesel exhaust Exhaust heat exchanger prototypes from Bosal, sized using TCO analysis Expander prototype from Exoès, tailored for HD truck market Test results Amesim model calibrated using static and dynamic tests Peak thermal efficiency of 11%, net drivecycle fuel saving 3.5% Payback time of 2 years for a WHR system

23 Questions Maximilian Hombsch Keivan Shariatmadar Davy Maes Stephan Schlimpert Stefan Pas Filip Dörge