Nested Reducing Agent Tank for Freeze-Thaw Availability
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Solution Overview
Problem
Existing reducing agent tanks in internal combustion engines, especially in passenger cars, face challenges in maintaining the availability of reducing agents at temperatures below -11°C, as they typically freeze and are difficult to thaw using engine coolant due to the distance between the engine and the tank, limiting operation in colder climates.
Innovation Solution
A tank design featuring an external container with an internal container and a heating element, where the reducing agent in the internal container is thawed first and then flows into the external container, aided by heat-conducting baffles and sloshing motion during vehicle movement, ensuring continuous operation at lower temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the reducing agent is stored in a single large tank, then the storage capacity is maximized, but the reducing agent freezes at temperatures below -11°C and cannot be adequately thawed
Solution Approach 1:
The tank is divided into an internal container and an external container, both filled with reducing agent. The heating element is placed in the internal container to thaw it first, then the thawed liquid flows into the external container to thaw the frozen reducing agent there. This segmentation allows effective thawing while maintaining full storage capacity.
Solution Approach 2:
The internal container is nested within the external container, both containing reducing agent. The heating element in the inner container thaws the reducing agent, which then flows outward to thaw the outer container's contents. This nested structure enables sequential thawing from inside to outside while maximizing space utilization.
2Reliability
If engine coolant heating is used, then the entire tank can be thawed, but the engine and tank are located far apart making this difficult in passenger cars
Solution Approach 1:
The heating function is extracted from the engine coolant system and implemented as a self-contained heating element within the reducing agent tank. This eliminates the need for complex coolant routing to the tank while maintaining effective thawing capability.
Solution Approach 2:
The thawed liquid reducing agent acts as an intermediary heat transfer medium. It absorbs heat from the heating element in the internal container, then flows into the external container to transfer heat to the frozen reducing agent, effectively distributing thermal energy throughout the tank.
3Device complexity
If only a partial volume is heated electrically, then the heating system is simple, but the thawed volume is insufficient for operation beyond temperate climate zones
Solution Approach 1:
The system uses its own contents (liquid reducing agent) as the heat transfer medium. The heated liquid circulates and thaws the frozen portions, eliminating the need for separate coolant systems while enabling complete tank thawing and extended operational duration.
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 design allows for uninterrupted operation by effectively thawing the reducing agent in the external container, ensuring a sufficient supply even at temperatures below -11°C, thus meeting exhaust gas composition demands in colder climates.
Implementation Method 1
a heating element is received in the internal container
Implementation Method 2
heat-conducting baffles that protrude into the external container are embodied on the internal container
Implementation Method 3
When motion of the tank occurs, already-thawed reducing agent sloshes through the at least one opening from the internal container into the external container
Data Source
AI summary
The invention relates to a tank for storing a reducing agent, in particular a liquid reducing agent. The reducing agent reduces the nitrogen oxides from the waste gases of the internal combustion engine to nitrogen and water. The tank includes an external container in which an internal container is accommodated. A heating element is provided in the internal container and the liquid reducing agent can be removed by a removal device. The internal container is connected to the external container in such a way that the liquid reducing agent can flow out from the internal container into the external container.