Electrically Heated Catalyst for Cold Start Emissions
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Solution Overview
Problem
Compression ignition engines emit pollutants like carbon monoxide, hydrocarbons, and oxides of nitrogen, which are challenging to control quickly, especially during cold starts, due to the slow heating up of oxidation catalysts, leading to non-compliance with stringent emission regulations.
Innovation Solution
A system integrating a hydrocarbon adsorbent first honeycomb substrate and an electrically heatable, catalysed second honeycomb substrate with a central processing unit controlling the heating and fuel injection timing to rapidly reach effective operating temperatures, promoting swift catalyst light-off and efficient conversion of pollutants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an oxidation catalyst is used to treat CO and HC emissions, then pollutant conversion is improved, but the catalyst takes several minutes to heat up to effective operating temperature from cold start, leading to significant pollutant emissions during this period
Solution Approach 1:
The patent applies preliminary action by using an electric heater to pre-heat the oxidation catalyst before the engine starts or during cold operation. This ensures the catalyst reaches its light-off temperature quickly, eliminating the delay in pollutant conversion during cold starts. The heater is activated in advance to prepare the catalyst for immediate operation when the engine starts.
2Loss of time
If an electric heater is incorporated into the exhaust system to heat the catalyst quickly, then the time to reach operating temperature is reduced, but the system complexity and energy consumption increase
Solution Approach 1:
The patent merges the electric heater with the oxidation catalyst assembly, integrating both components into a single unit. This combination reduces system complexity by eliminating separate heating and catalytic conversion components, while still achieving rapid heating of the catalyst to operating temperature.
3Loss of time
If an electric heater is incorporated into the exhaust system to heat the catalyst quickly, then the time to reach operating temperature is reduced, but energy consumption increases
Solution Approach 1:
The patent applies periodic action by controlling the electric heater to operate only during specific periods when needed - primarily during cold starts or when the catalyst temperature drops below the light-off temperature. The heater is turned off once the catalyst reaches operating temperature, reducing unnecessary energy consumption while maintaining rapid heating capability when required.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system achieves significant reduction in CO2, hydrocarbon, carbon monoxide, and NOx emissions by rapidly heating the catalysts, ensuring compliance with test cycles like WLTP and RDE, and maintaining efficient NOx conversion even during idling or stop-start conditions.
Implementation Method 1
an electrically heatable element... pre-programmed, when in use, to control a heating activation state of the electrically heatable element
Implementation Method 2
treat carbon monoxide (CO) by oxidising it to carbon dioxide (CO2), and treat hydrocarbons (HCs) by oxidising them to water (H2O) and carbon dioxide (CO2)
Data Source
AI summary
A system comprising (i) a vehicular compression ignition engine comprising one or more engine cylinders and one or more electronically-controlled fuel injectors therefor; (ii) an exhaust line for the engine comprising: a first emissions control device comprising a first honeycomb substrate, which comprises a hydrocarbon adsorbent component; and a second emissions control device comprising an electrically heatable element and a catalysed second honeycomb substrate, which comprises a rhodium-free platinum group metal comprising platinum, wherein the electrically heatable element is disposed upstream from the catalysed second honeycomb substrate and wherein both the electrically heatable element and the catalysed second honeycomb substrate are disposed downstream from the first honeycomb substrate; a third emissions control device, which is a third honeycomb substrate comprising an ammonia-selective catalytic reduction catalyst disposed downstream from the second emissions control device; and one or more temperature sensors located: upstream of the electrically heatable element and/or upstream of the first honeycomb substrate; and between the electrically heatable element and the catalysed second honeycomb substrate; and (iii) an engine control unit comprising a central processing unit pre-programmed, when in use, to control both a heating activation state of the electrically heatable element; an injection timing strategy of the one or more electronically-controlled fuel injector to increase the temperature of at least the first emissions control device following key-on/cold-starting a vehicle comprising the system, wherein the one or more temperature sensors are electrically connected to the engine control unit for feedback control in the system.