Evacuated Urea Delivery Path Thermal Insulation
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Solution Overview
Problem
Devices for providing liquid additives, such as urea-water solutions used in SCR methods for reducing nitrogen oxide emissions, often freeze at low temperatures, leading to operational delays due to the need for thawing or evacuation, which requires significant energy and time.
Innovation Solution
A method involving a delivery path with a jacket section that is evacuated to form a thermal insulator, reducing heat conduction and allowing for targeted heating, thereby minimizing freezing and enabling quicker startup after a standstill, by using a substitute substance with lower thermal conductivity, such as air, to insulate the delivery path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heaters are provided to prevent freezing or thaw frozen liquid additive, then the liquid additive can be kept from freezing or thawed, but the device requires significant energy and time to operate, especially after long standstill periods
Solution Approach 1:
The delivery path is evacuated before the liquid additive can freeze, removing the additive from the delivery path in advance. This preliminary evacuation prevents the need for subsequent heating operations, as the frozen additive simply needs to be pumped back into the tank rather than thawed in place.
Solution Approach 2:
The liquid additive is extracted from the delivery path by evacuating it back into the tank. This removes the problematic frozen substance from the heating zone, eliminating the need for energy-intensive in-place thawing operations while maintaining system reliability.
2Reliability
If the delivery path is evacuated to prevent freezing, then freezing cannot occur in evacuated sections, but the device complexity increases due to additional evacuation mechanisms
Solution Approach 1:
The pump already present in the device for delivering liquid additive is made multi-functional by enabling it to operate in reverse for evacuation. This single component performs both delivery and evacuation functions, avoiding the need for separate evacuation mechanisms and reducing overall device complexity.
Solution Approach 2:
The pump's operational mode is made dynamic and adjustable, allowing it to switch between forward delivery and reverse evacuation operations. This dynamic capability enables the system to adapt its function based on operational needs without adding permanent structural complexity.
3Ease of operation
If heaters are used to thaw frozen liquid additive, then the additive can be restored to liquid state, but the startup time is extended due to the time required to provide sufficient heating energy
Solution Approach 1:
The liquid additive is evacuated from the delivery path before freezing occurs during standstill periods. This preliminary action prevents the formation of large volumes of frozen additive that would require extended thawing time, enabling faster device startup when operation is resumed.
Solution Approach 2:
Instead of undergoing the time-consuming thawing process, the system skips directly to operation by pumping the already-evacuated liquid additive back into the tank and refilling the delivery path, bypassing the intermediate thawing stage entirely.
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
This approach significantly reduces the frequency of freezing events, allows for quicker device startup, and prevents unnecessary heat transfer, ensuring the device remains operational even with frozen additives by controlling heat distribution effectively.
Implementation Method 1
at least partially evacuating the section of the delivery path; and forming a thermal insulator in the jacket by the evacuated delivery path
Implementation Method 2
at least partially evacuating the section of the delivery path
Implementation Method 3
heaters to be provided in the devices for providing liquid additive, by which heaters at least parts of the device can be heated
Data Source
AI summary
A method for operating a device for providing a liquid additive, the device having a delivery path running from a tank to an additive dispensing device, at least one section of the delivery path forming a jacket, includes: delivering the liquid additive from the tank to the additive dispensing device along the delivery path in a delivery direction; stopping the delivery of the liquid additive; at least partially evacuating the section of the delivery path; and forming a thermal insulator in the jacket by the evacuated delivery path.