Formation of NH 3 and N 2 O in a modern natural gas three-way catalyst designed for heavy-duty vehicles: the effects of simulated exhaust gas composition and ageing

High EGR rates combined with turbocharging has been identified as a promising way to increase the maximum load and efficiency of heavy duty spark ignition Natural Gas engines. With stoichiometric conditions a three way catalyst can be used which means that regulated emissions can be kept at very low levels. Most of the heavy duty NG engines are diesel engines which are converted for SI operation. These engine’s components are in common with the diesel-engine which put limits on higher exhaust gas temperature. The engines have lower maximum load level than the corresponding diesel engines. This is mainly due to the lower density of NG, lower compression ratio and limits on knocking and also high exhaust gas temperature. They also have lower efficiency due to mainly the lower compression ratio and the throttling losses. However performing some modifications on the engines such as redesigning the engine’s piston in a way to achieve higher compression ratio and more turbulence, modifying EGR system and optimizing the turbocharging system will result in improving the overall efficiency and the maximum load limit of the engine. This paper presents the detailed information about the engine modifications which result in improving the overall efficiency and extending the maximum load of the engine. Control-related problems associated with the higher loads are also identified and appropriate solutions are suggested.

Download Full-text

3 kW Thermoelectric Generator for Natural Gas-Powered Heavy-Duty Vehicles—Holistic Development, Optimization and Validation

Energies ◽

10.3390/en15010015 ◽

2021 ◽

Vol 15 (1) ◽

pp. 15

Author(s):

Lars Heber ◽

Julian Schwab ◽

Timo Knobelspies

Keyword(s):

Natural Gas ◽

Thermoelectric Generator ◽

Functional Model ◽

Simultaneous Optimization ◽

Heavy Duty ◽

Holistic Model ◽

Average Deviation ◽

Vehicle Class ◽

Thermoelectric Modules ◽

Heavy Duty Vehicles

Emissions from heavy-duty vehicles need to be reduced to decrease their impact on the climate and to meet future regulatory requirements. The use of a cost-optimized thermoelectric generator based on total cost of ownership is proposed for this vehicle class with natural gas engines. A holistic model environment is presented that includes all vehicle interactions. Simultaneous optimization of the heat exchanger and thermoelectric modules is required to enable high system efficiency. A generator design combining high electrical power (peak power of about 3000 W) with low negative effects was selected as a result. Numerical CFD and segmented high-temperature thermoelectric modules are used. For the first time, the possibility of an economical use of the system in the amortization period of significantly less than 2 years is available, with a fuel reduction in a conventional vehicle topology of already up to 2.8%. A significant improvement in technology maturity was achieved, and the power density of the system was significantly improved to 298 W/kg and 568 W/dm3 compared to the state of the art. A functional model successfully validated the simulation results with an average deviation of less than 6%. An electrical output power of up to 2700 W was measured.

Download Full-text

Onboard Natural Gas Reforming for Heavy Duty Vehicles

SAE International Journal of Commercial Vehicles ◽

10.4271/02-12-01-0004 ◽

2019 ◽

Vol 12 (1) ◽

pp. 45-56 ◽

Cited By ~ 2

Author(s):

Brian Weiss ◽

Tilman W. Beutel ◽

Bryan R. Chapman ◽

Jonathan D. Saathoff ◽

Shamel Merchant ◽

...

Keyword(s):

Natural Gas ◽

Heavy Duty ◽

Natural Gas Reforming ◽

Heavy Duty Vehicles

Download Full-text

Effects of natural gas composition and compression ratio on the thermodynamic and combustion characteristics of a heavy-duty lean-burn SI engine fueled with liquefied natural gas

Fuel ◽

10.1016/j.fuel.2019.115733 ◽

2019 ◽

Vol 254 ◽

pp. 115733 ◽

Cited By ~ 17

Author(s):

Xiongbo Duan ◽

Yiqun Liu ◽

Ming-Chia Lai ◽

Genmiao Guo ◽

Jingping Liu ◽

...

Keyword(s):

Natural Gas ◽

Compression Ratio ◽

Liquefied Natural Gas ◽

Combustion Characteristics ◽

Gas Composition ◽

Heavy Duty ◽

Si Engine ◽

Lean Burn

Download Full-text

Application of PdCe-HMOR Catalyst as NOx CH4-SCR System for Heavy-Duty Vehicles Moved by Natural Gas

Topics in Catalysis ◽

10.1007/s11244-016-0578-y ◽

2016 ◽

Vol 59 (10-12) ◽

pp. 982-986 ◽

Cited By ~ 3

Author(s):

A. Nobre Mendes ◽

V. Lauga ◽

S. Capela ◽

M. F. Ribeiro ◽

P. Da Costa ◽

...

Keyword(s):

Natural Gas ◽

Heavy Duty ◽

Scr System ◽

Heavy Duty Vehicles

Download Full-text

Effects of operating condition on particulate matter and nitrogen oxides emissions from a heavy-duty direct injection natural gas engine using cooled exhaust gas recirculation

International Journal of Engine Research ◽

10.1243/1468087042674634 ◽

2004 ◽

Vol 5 (6) ◽

pp. 499-511 ◽

Cited By ~ 2

Author(s):

G P McTaggart-Cowan ◽

S N Rogak ◽

P G Hill ◽

W K Bushe ◽

S R Munshi

Keyword(s):

Particulate Matter ◽

Natural Gas ◽

Nitrogen Oxides ◽

Direct Injection ◽

Exhaust Gas Recirculation ◽

Exhaust Gas ◽

Heavy Duty ◽

Gas Engine ◽

Natural Gas Engine ◽

Gas Recirculation

Download Full-text

Short-circuit effects on spark ignition engine after-treatment and fuel-to-air ratio control

International Journal of Engine Research ◽

10.1177/1468087418796705 ◽

2018 ◽

Vol 21 (5) ◽

pp. 885-894

Author(s):

Carlos Guardiola ◽

Benjamín Pla ◽

Marcelo Real ◽

Cyril Travaillard ◽

Frederic Dambricourt

Keyword(s):

Control Strategy ◽

Short Circuit ◽

Point Of View ◽

Spark Ignition Engine ◽

Exhaust Gas ◽

Gas Composition ◽

Engine Emissions ◽

The Impact ◽

Three Way Catalyst ◽

Catalyst Efficiency

The short circuit of fresh air is a more and more extended strategy to deal with low-end torque issues, very common in small turbocharged and spark-ignited four-stroke engines. Therefore, from the author’s point of view, it is interesting to check whether the after-treatment system can work properly under these conditions. In the present study, the effect of the fresh air short-circuit on engine emissions has been assessed through its impact on the wideband [Formula: see text] sensor and the three-way catalyst behaviour, which are the key elements of the fuel-to-air ratio control strategy. In particular, the analysis of the sensor dynamic response shows that the [Formula: see text] sensor overestimates the fuel-to-air ratio under short-circuit conditions. The sensor overestimation leads the actual fuel-to-air ratio out of the proper three-way catalyst window; in this sense, results show a non-negligible emissions increase, especially in terms of NOx. Regarding the impact on the three-way catalyst behaviour, the study shows how short-circuit pulses change the exhaust gas composition for a given fuel-to-air ratio at catalyst inlet, which also contributes to a penalty in the three-way catalyst efficiency.

Download Full-text