Heating and storage: A review on exhaust thermal management applications for a better trade-off between environment and economy in ICEs

Hu, Jie; Wu, Yan; Liao, Jianxiong; Cai, Zhizhou; Yu, Qinghua

doi:10.1016/j.applthermaleng.2022.119782

Cited by 5 publications

(2 citation statements)

References 134 publications

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“…Therefore, for an additional reduction in NOx, the utilization of the SCR catalyst in the early stage of the NRTC mode is important, and rapid heat up of the exhaust temperature is important for this purpose. Various methods are being investigated to increase the exhaust gas temperature for rapid activation of the catalyst in the cold mode, such as the post-injection in-cylinder method [30][31][32], mini or proper type burners [30,33], and electrical heaters [18,30,34], among which the electrical heated catalyst (EHC)-based heating method is actively being considered to reduce exhaust emissions from small to medium-sized engines [22,[35][36][37], due to its advantages of fast response time, system compactness, and independence from engine operation, taking into account electrification (48 V, HEV, PHEV, etc.) of various mobilities (Table 1).…”

Section: Introductionmentioning

confidence: 99%

Fuel Consumption and Emission Reduction for Non-Road Diesel Engines with Electrically Heated Catalysts

Lee

et al. 2023

Catalysts

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In this study, an exhaust system compliant with future regulations was developed for a non-road 110PS engine with a Tier-4f aftertreatment system, and the emission characteristics of the engine were investigated in the non-road transient mode (NRTC). For the system to comply with future exhaust regulations, a DPF was installed, and an electrical heated catalyst (EHC) device was installed to manage exhaust gas temperature. The emission characteristics of exhaust gas were examined according to the power and applied duration of EHC, and the effects of catalyst coating and the urea water solution (UWS) injection map on NOx reduction, NH3 slip, and N2O emissions in NRTC mode were investigated. The application of a 4 kW class EHC system enables the lowering of the injection starting temperature of the UWS, as reliable gas heating (heating duration control) is guaranteed. When the injection starting temperature (based on the SCR inlet temperature) was set to 150 °C, NSR map, (III) in conjunction with the operation of the EHC, effectively achieved significant NOx reduction in NRTC mode without deposit and wetting occurring in the mixer and exhaust pipe. Regarding changes in EHC power from 3 kW to 4 kW, it was observed that a NOx reduction of 0.05 g/kWh occurs in the cold NRTC mode, but in the hot NRTC mode, it was found that the relative decrease in the UWS is due to the increased NO2 conversion efficiency as a result of the oxidation catalyst, making 3 kW more advantageous. Furthermore, due to the increase in NO2 concentration caused by the oxidation catalyst and the increase in the low-temperature injected UWS, NH4NO3 was formed, which resulted in an increase in PM emissions and a significant increase in N2O emissions around an exhaust temperature of 250 °C. When the EHC power was set to 3 kW and the volume of oxidation catalyst and the amount of UWS injection were adjusted, applying EHC in the NRTC mode resulted in an additional NOx reduction of 58.6% and 88.4% in cold and hot modes, respectively, compared with not using EHC, with a fuel penalty of approximately 1.67%, while limiting the peak concentrations of N2O and NH3.

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Section: Introductionmentioning

confidence: 99%

Fuel Consumption and Emission Reduction for Non-Road Diesel Engines with Electrically Heated Catalysts

Lee

et al. 2023

Catalysts

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“…The application of multiple VVT for enhanced EAT warmup in low-load conditions is relatively inadequate in the literature [22,43]. Previous works demonstrated that the implementation of single-VVT has a definite potential on EAT warmup.…”

Section: Introductionmentioning

confidence: 99%

Enhanced Exhaust after-Treatment Warmup in a Heavy-Duty Diesel Engine System via Miller Cycle and Delayed Exhaust Valve Opening

Başaran

2023

Energies

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The exhaust after-treatment (EAT) threshold temperature is a significant concern for highway vehicles to meet the strict emission norms. Particularly at cold engine start and low loads, EAT needs to be improved above 250 °C to reduce the tailpipe emission rates. Conventional strategies such as electrical heating, exhaust throttling, or late fuel injection mostly need a high fuel penalty for fast EAT warmup. The objective of this work is to demonstrate using a numerical model that a combination of the Miller cycle and delayed exhaust valve opening (DEVO) can improve the tradeoff between EAT warmup and fuel consumption penalty. A relatively low-load working condition (1200 RPM speed and 2.5 bar BMEP) is maintained in the diesel engine model. The Miller cycle via retarded intake valve closure (RIVC) is noticeably effective in increasing exhaust temperature (as high as 55 °C). However, it also dramatically reduces the exhaust flow rate (over 30%) and, thus, is ineffective for rapid EAT warmup. DEVO has the potential to enhance EAT warmup via increased exhaust temperature and increased exhaust flow rate. However, it considerably decreases the brake thermal efficiency (BTE)—by up to 5%—due to high pumping loss in the system. The RIVC + DEVO combined technique can elevate the exhaust temperature above 250 °C with improved fuel consumption—up to 10%—compared to DEVO alone as it requires a relatively lower rise in pumping loss. The combined method is also superior to RIVC alone. Unlike RIVC alone, the RIVC + DEVO combined mode does not need the extreme use of RIVC to increase engine-out temperature above 250 °C and, thus, provides relatively higher heat transfer rates (up to 103%) to the EAT system through a higher exhaust flow rate. The RIVC + DEVO combined method can be technically more difficult to implement compared to other methods. However, it has the potential to maintain accelerated EAT warmup with improved BTE and, thus, can keep emission rates at low levels during cold start and low loads.

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Temperature-based thermo-electric coupling maximum power point tracking algorithm for thermoelectric generation systems under transient conditions

Ding

Cai

Deng

2023

Applied Thermal Engineering

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Heating and storage: A review on exhaust thermal management applications for a better trade-off between environment and economy in ICEs

Cited by 5 publications

References 134 publications

Fuel Consumption and Emission Reduction for Non-Road Diesel Engines with Electrically Heated Catalysts

Fuel Consumption and Emission Reduction for Non-Road Diesel Engines with Electrically Heated Catalysts

Enhanced Exhaust after-Treatment Warmup in a Heavy-Duty Diesel Engine System via Miller Cycle and Delayed Exhaust Valve Opening

Temperature-based thermo-electric coupling maximum power point tracking algorithm for thermoelectric generation systems under transient conditions

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