Flow Heater Bypass Passage Design to Prevent Bubble Accumulation
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Solution Overview
Problem
Gas bubbles in the water circuit of motor vehicles can impair heat transfer in flow heaters by accumulating on the heating plate, reducing efficiency.
Innovation Solution
A bypass passage is connected in parallel to the heated section of the flow passage, creating a pressure differential to draw bubbles away from the heating plate, with a higher flow resistance in the bypass passage to ensure efficient bubble removal, and a design that utilizes a widening passage before the heated section and narrowing after to enhance the pressure differential.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bypass passage is added to remove gas bubbles, then heat transfer efficiency is improved, but device complexity increases
Solution Approach 1:
The bypass passage serves multiple functions: it acts as a gas bubble removal channel while also serving as part of the liquid flow path during normal operation. This multi-functionality allows the device to maintain high heat transfer efficiency by removing bubbles without requiring a completely separate gas removal system, thus limiting the increase in device complexity.
Solution Approach 2:
The bypass passage acts as an intermediary structure that mediates between the heated section and the outlet. It provides a dedicated path for gas bubbles to escape while allowing liquid to flow through the heated section, resolving the conflict between maintaining simple structure and achieving reliable bubble removal for efficient heat transfer.
2Reliability
If the bypass passage has high flow resistance to preferentially remove bubbles, then bubble removal efficiency is improved, but pressure loss increases
Solution Approach 1:
The bypass passage is designed with locally optimized properties: it has higher flow resistance than alternative paths to preferentially guide gas bubbles through it, but this resistance is carefully controlled to limit overall pressure loss. The local quality of the bypass passage (its resistance characteristics) is tailored to achieve selective bubble removal while minimizing energy loss in the overall system.
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 solution effectively prevents bubble accumulation on the heating plate, maintaining high efficiency and compact design by ensuring efficient heat transfer and bubble removal, even when gas bubbles are present in the liquid.
Implementation Method 1
heat transfer from the heating plate, which carries an electrical heating resistance, to the liquid
Implementation Method 2
When liquid flows through the heated section of the flow passage, friction causes a loss of pressure
Implementation Method 3
This pressure differential can be used to suck any bubbles that may be present into the bypass passage
Implementation Method 4
The flow heater is intended to be oriented in operation such that the beginning of the bypass passage is on an upper wall of the flow passage. Gravity then causes any bubbles to rise such they can enter the bypass passage more easily
Data Source
AI summary
Disclosed is a flow heater with a housing having an inlet and an outlet. A flow passage for liquid that is to be heated runs from the inlet to the outlet. A heating plate is arranged as wall of a heated section of the flow passage. A bypass passage is provided in parallel to the heated section of the flow passage in order to guide any gas bubbles contained in the liquid from the fluid inlet to the fluid outlet without passing through the heated section of the flow passage.