Passive Reactant Injection Unit for Exhaust Gas Mixing
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Solution Overview
Problem
Existing devices for releasing reactants into the exhaust gas stream of internal combustion engines face inefficiencies in mixing reactants with exhaust gases, particularly at lower temperatures, leading to incomplete evaporation and increased reactant consumption.
Innovation Solution
A device with a passively operating reactant injection unit that switches states based on pressure, combined with a heating unit and dual pumps to maintain reactant pressure above vapor pressure but below switching pressure, ensuring efficient evaporation and mixing without residual volumes for byproduct formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If reactant is heated to high temperature and pressurized to prevent evaporation before release, then spontaneous evaporation and fine droplet formation occur upon release, but the device complexity increases due to heating unit and pressure control requirements
Solution Approach 1:
The reactant injection unit is designed to automatically switch between locked and open states based on reactant pressure alone, without requiring external actuators or control systems. The passive design uses the pressure differential between the reactant delivery unit and the injection unit to trigger automatic injection, eliminating the need for complex actuation mechanisms while maintaining precise control over the injection timing and amount.
Solution Approach 2:
The system utilizes changes in reactant pressure and temperature as key parameters to control the injection process. By heating the reactant to elevated temperatures and maintaining pressure differentials between units, the system triggers spontaneous evaporation and phase change upon pressure release, achieving fine droplet formation and efficient mixing without requiring complex mechanical injection mechanisms.
2Loss of substance
If reactant pressure is maintained above vapor pressure to prevent evaporation, then evaporation is suppressed before release, but the reactant consumption increases due to incomplete evaporation at lower temperatures
Solution Approach 1:
The reactant is pre-heated to elevated temperatures (e.g., 200°C or higher) before being introduced into the injection unit. This preliminary heating ensures that when the reactant is released and pressure drops, spontaneous evaporation occurs immediately, even in exhaust gas streams with relatively low temperatures. The pre-heating action prepares the reactant in advance to achieve complete vaporization and mixing, preventing incomplete evaporation and reducing unreacted reactant losses.
Solution Approach 2:
The system exploits phase transition from liquid to vapor through spontaneous evaporation upon pressure release. By maintaining the reactant above its vapor pressure during delivery and then allowing rapid pressure decompression at the injection point, the reactant undergoes immediate phase change, forming fine droplets that rapidly evaporate and mix with the exhaust gas. This phase transition mechanism ensures complete evaporation even at lower exhaust gas temperatures, improving reactant utilization efficiency.
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
Enables efficient mixing of reactants with exhaust gases at lower temperatures, reducing reactant consumption and enabling improved NOx conversion with a smaller catalytic converter volume, and faster evaporation due to fine droplet formation, thus optimizing reactant utilization.
Implementation Method 1
a heating unit for heating reactant delivered by the reactant delivery unit to the reactant injection unit
Implementation Method 2
a spontaneous expansion, which leads to a spontaneous evaporation of the reactant, occurs
Implementation Method 3
a spontaneous expansion, which leads to a spontaneous evaporation of the reactant
Implementation Method 4
the reactant fed in liquid form into the exhaust gas stream before release is set under such high pressure that an evaporation of reactant before the release of reactant into the exhaust gas stream cannot occur
Implementation Method 5
a spontaneous expansion, which leads to a spontaneous evaporation of the reactant, occurs
Data Source
AI summary
A device for releasing reactant (R) into the exhaust gas stream (A) of an internal combustion engine, includes a reactant injection unit (20), a reactant delivery unit (12) for delivering reactant (R) from a reactant reservoir (14) to the reactant injection unit (20), and a heating unit (18) for heating reactant (R) delivered by the reactant delivery unit (12) to the reactant injection unit (20). The reactant injection unit (20) is switchable as a function of a reactant pressure generated by the reactant delivery unit (12) between an open state for releasing reactant (R) and a locked state for preventing the release of reactant.