Variable Buoyancy Heater for Urea Thawing
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Solution Overview
Problem
Fixed heaters in diesel exhaust treatment systems become less effective as the urea solution freezes, leading to an air gap formation and reduced thawing efficiency due to increased distance between the heater and frozen urea, resulting in inadequate urea supply for emissions reduction at temperatures below -11°C.
Innovation Solution
A variable buoyancy heater with a float and integrated heating element that changes buoyancy based on temperature, allowing it to float on thawed urea and sink in frozen urea, maintaining proximity and efficiency throughout the thawing process, using a variable volume element that expands with heating to become positively buoyant and decreases to become negatively buoyant.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If a fixed heater is placed at the bottom of the container, then the heater can provide continuous heating, but the heater becomes less effective as the thawed urea rises and an air gap forms between the heater and frozen urea
Solution Approach 1:
The heater is made buoyant and capable of moving vertically within the container. As urea melts from the bottom up, the heater automatically rises with the liquid level, maintaining constant contact with the frozen urea surface. This dynamic positioning resolves the contradiction by allowing continuous heating operation while preventing the formation of an insulating air gap, thus maintaining heating effectiveness throughout the thawing process.
2Device complexity
If the heater remains stationary at the bottom, then the device structure is simple, but the distance between the heater and frozen urea increases as thawing progresses
Solution Approach 1:
The heater is equipped with a buoyancy control mechanism that allows it to move vertically. As the urea solution thaws and the liquid level rises, the heater automatically ascends to maintain proximity to the frozen urea interface. This dynamic adjustment prevents the distance from increasing, resolving the contradiction between structural simplicity and maintaining effective heating distance.
3Ease of manufacture
If a fixed heater is used, then manufacturing is straightforward, but an air gap forms that insulates the frozen urea from the heater
Solution Approach 1:
The heater is designed with buoyant properties enabling it to float and move with the rising liquid level during thawing. This dynamic behavior prevents the formation of an air gap between the heater and frozen urea, eliminating the insulating effect that would otherwise develop. The solution maintains manufacturing feasibility while preventing the harmful air gap formation through the heater's ability to self-adjust its position.
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 variable buoyancy heater maintains intimate contact with frozen urea, enhancing thawing efficiency and reducing electrical power consumption while ensuring a consistent urea supply for emissions control, even at low temperatures.
Implementation Method 1
the variable volume element expands based on a temperature increase from the heating element
Implementation Method 2
the variable volume element expands based on a temperature increase from the heating element, such that the variable buoyancy float becomes positively buoyant when the variable volume element expands
Data Source
Figure 1~2
Figure 3
Figure 4~5B
AI summary
A variable buoyancy heater (100) is provided. It comprises variable buoyancy float (123) that includes a variable volume element (120). A first fluid is contained within the variable volume element and a heating element (120) that is integral with the variable buoyancy float (100) is provided. The heating element (120) is arranged to heat the first fluid wherein the variable volume element (122) expands based on a temperature increase from the heating element (120), such that the variable buoyancy float (123) becomes positively buoyant when the variable volume element (122) expands and negatively buoyant when the heating element (120) is off.