Reductant Injector Cooling via Siphon Convection
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Solution Overview
Problem
Fluid injectors in exhaust aftertreatment systems face overheating issues due to prolonged valve closure, leading to potential corrosion and boiling, and existing cooling solutions add complexity or require vehicle motion for effective heat transfer.
Innovation Solution
A cooling system for reductant injectors in emissions modules, utilizing a coolant siphon tank with a gravitational elevation greater than the injector, enabling buoyant convection to transfer heat away from the injector, and an auxiliary pump for forced convection when the engine is shut down.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the injector valve is positioned close to the injector nozzle tip, then injection spray characteristics and mechanical packaging are improved, but the injector valve experiences detrimental overheating
Solution Approach 1:
The cooling system is segmented into multiple functional components: a cooling passage within the injector, a siphon tank positioned above the injector, and a supply pump. This segmentation allows the cooling function to be independently optimized from the injection function, enabling close valve-to-nozzle positioning while maintaining effective cooling through the dedicated cooling passage and siphon tank arrangement.
Solution Approach 2:
Coolant serves as an intermediary substance that transfers heat away from the injector valve. The cooling passage conducts heat to the coolant, which then transports the heat to the siphon tank. This intermediary cooling mechanism enables the valve to be positioned close to the nozzle without direct thermal exposure to the exhaust stream.
2Temperature
If fluid flows through the injector, then heat is transferred away from the injector, but the valve must close for significant time durations which stops cooling
Solution Approach 1:
The siphon tank is pre-filled with coolant and positioned above the injector before the valve closes. When the valve closes and stops reductant flow, the pre-positioned siphon tank continues to supply coolant through the cooling passage via gravitational convection, maintaining cooling during the valve closure period without requiring continuous reductant flow.
Solution Approach 2:
The cooling system operates autonomously during valve closure through gravitational convection. The siphon tank's elevated position creates a self-sustaining flow where coolant naturally circulates through the cooling passage without requiring external power or continuous reductant flow, enabling the system to cool the injector during periods when the valve is closed.
3Temperature
If a cooling device is added to transfer heat from the cooling circuit, then cooling effectiveness is improved, but system complexity increases and vehicle motion is required
Solution Approach 1:
The cooling system utilizes the engine's existing operational characteristics to drive cooling without additional complexity. The siphon tank's elevated position creates gravitational convection that automatically circulates coolant during engine operation. The system leverages the engine's motion and thermal characteristics rather than adding separate active cooling mechanisms, thereby avoiding increased system complexity.
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
Effectively cools the reductant injector through natural buoyant convection and forced convection, preventing overheating and corrosion, even after engine shutdown, without adding unnecessary complexity or requiring vehicle motion.
Implementation Method 1
transporting at least a portion of the coolant from the cooling passage of the reductant injector to a siphon tank via buoyant convection
Implementation Method 2
transferring heat from the reductant injector to coolant provided by the cooling system auxiliary pump
Data Source
AI summary
A system for cooling a reductant injector in an emissions module is provided. The system includes an emissions module, coupled to an engine exhaust duct, and a cooling system fluidly coupled to the emissions module. The emissions module includes a reductant system and a selective catalytic reduction (SCR) module. The reductant system includes a reductant injector having a cooling passage. The cooling system includes a reservoir tank, a supply pump fluidly coupled to the reservoir tank, and a siphon tank fluidly coupled to the supply pump and the reductant injector cooling passage. The siphon tank is disposed proximate to the reductant injector, and a gravitational elevation of a base of the siphon tank is greater than a gravitational elevation of the reductant injector.