Vehicle Waste Heat Recovery Using Thermally Regenerative Fuel

CellsAndrew Carrier1, Dominik Wechsler1, Philip Jessop1, Boyd Davis2

1Department of Chemistry2Queen’s-RMC Fuel Cell Research CentreQueen’s UniversityKingston, Ontario, Canada

Hydrogen + Fuel Cells 2009Vancouver, BC, CANADAJune 2, 2009

Problem• Transport trucks use

~ $5.3 billion worth of fuel a year in Canada.

• About 70% of fuel energy is lost as waste heat from the exhaust and engine block.

• Recovery of some waste heat would result in significant fuel savings.

heatingof exhaust

heatingof engine

auxiliary electrical systems

energy from fuel

Proposed Solution• Thermally regenerative fuel

cell (TRFC).• Fuel cell could power a

hybrid electric engine or auxiliary components.

• Vehicle radiator would be replaced with dehydrogenation reactor.

• Fuel cell would be used to charge a battery which could then be used for electric assist driving or in place of idling an engine.

reactor

wasteheat

B

A

H2

fuel cell

A B + H2

electricity

-CONFIDENTIAL- 4

Recovery Goal• For diesel trucks ~ 40% lost as waste heat• Goal is to capture 10% of this heat

– (4% of fuel saved)• Value greater since it would replace APU electricity

• Average transport truck mileage is about 100,000 km with annual fuel costs of $30K

• 5% savings is $1500 per year• Payback 3 years on 20 year lifespan

assuming 5K installation

Recovery GoalLong haul trucking ideal for product entry• High fuel consumption• Low braking (no regenerative braking)• High APU demand• Underhood space• Fuel cell would act in a non-critical role• Emissions with start and stop trucking

Fluid Properties• React with excellent selectivity• Liquid• Boiling point > 200 ºC• High thermal stability• Rapid reaction rates• Low cost• Low toxicity

State of the Art• Isopropanol-acetone system

(CH3)2CHOH (CH3)2CO + H2

– Aqueous system– Uses low quality heat (100 °C)– V and I both improved with higher

acetone/isopropanol ratio at cathode

Hydrogenation is favoured at low T Dehydrogenation is favoured at high T Reaction thermodynamics are understood Predictable equilibrium compositions Predictable cell voltages

Thermodynamics

Selectivity

S 3000 cycles 30 000 cycles

99.99% 74% 5%

99.995% 86% 22%

99.999% 97% 74%

The current selectivity is >99.9% which is the limit of detection for our analytical method.

Initial rate is 3.6 L‐H2 min-1 kg-1.

Rate decreases as reaction approaches equilibrium.

Reaction will reach steady state with that of the fuel cell.

Kinetics

0 10 20 30 40 50 600%

10%

20%

30%

40%

50%

H2 @ 200 °C 0.1 mol% Catalyst

t (min)

Hydrogenation proceeds in fuel cell. Cell potential drops rapidly if flow of

hydrogen acceptor across the cathode is stopped.

Cell potential is dependent on the difference of the fluid composition from its equilibrium composition.

Cell potential is highest when the difference between the two temperature regions is highest.

Fuel Cell

Technology would help the local automotive industry have an advantage in the international marketplace.

Decreased fuel cost decreases the cost of shipping goods.

Decreased fuel use lowers greenhouse gas emissions

Benefits

A number of candidate systems have been identified as a result of a screening of potential compounds

Two systems have been tested in a fuel cell coupled to a regeneration reactor.

Both performed well◦ Voltages as expected◦ Steady output◦ Membrane stable

Current Status

Develop system where dehydrogenated material boils at a substantially lower temperature.

Dehydrogenated material is concentrated in the cathode stream.

High rates are maintained. Cell potential is improved. Pumping requirements reduced.

Future Work

Explore commercially available materials Develop rapid catalyst screening methods Produce new catalysts in-house Run prototype fuel cells

◦ Integrated operation◦ Connect to diesel engine

Rate of heat absorption Economic evaluation following above work

◦ Non-automotive applications

Future Work

Questions