Heat-transfer device with a two-phase working fluid
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Solution Overview
Problem
Two-phase working fluid heat transfer devices face issues with vapor bubble formation in the liquid zone of the evaporator, leading to capillary structure drying and potential loss of priming.
Innovation Solution
A two-phase working fluid heat transfer device is designed with an evaporator having a liquid zone and a vapor zone, connected by communication circuits to a condenser and a reservoir. A selectively controlled energy supply element increases the pressure of the working fluid in the reservoir, allowing cooled fluid to flow into the liquid zone, condensing vapor bubbles and maintaining efficient heat transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the working fluid temperature in the liquid zone increases to improve heat transfer, then heat transfer efficiency is improved, but vapor bubbles form causing capillary structure drying and loss of priming
Solution Approach 1:
The invention introduces a preliminary cooling action by connecting the reservoir to the liquid zone through a third communication circuit with a cold source. This pre-cools the working fluid before it enters the liquid zone, preventing vapor bubble formation before it occurs. The selective energy supply element activates only when temperature thresholds are exceeded, providing timely intervention to maintain liquid state and prevent capillary drying.
Solution Approach 2:
The reservoir acts as an intermediary element between the hot source and the liquid zone. It receives excess hot working fluid, cools it down through the third communication circuit with the cold source, and returns cooled liquid to the liquid zone. This intermediary cooling mechanism prevents direct overheating of the liquid zone while maintaining overall heat transfer efficiency.
2Reliability
If the condenser is oversized to handle undercooling requirements, then heat transfer reliability is improved, but device complexity and size increase
Solution Approach 1:
The reservoir with the third communication circuit performs preliminary cooling of the working fluid before it returns to the evaporator. This pre-cooling action reduces the thermal load on the condenser, allowing it to be sized appropriately for its primary condensation function without requiring excessive oversizing to handle undercooling demands.
Solution Approach 2:
The cooling function is segmented into two distinct locations: the reservoir (with cold source) handles pre-cooling of liquid phase fluid, while the condenser focuses on condensing vapor phase fluid. This functional segmentation allows each component to be optimally sized for its specific task, reducing the need for an oversized condenser.
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 device effectively prevents vapor bubble formation in the liquid zone, maintaining the capillary structure's priming and enhancing heat transfer efficiency by ensuring the working fluid remains in a liquid state, thus avoiding undercooling and oversizing of the condenser.
Implementation Method 1
a selectively controlled energy supply element, adapted to increase the pressure of the working fluid contained in the reservoir
Implementation Method 2
by means of capillary pumping produced by a capillary structure of the evaporator
Implementation Method 3
part of the thermal power of the heat source is transferred to the evaporator structure and the capillary structure, thus producing an increase in the temperature of the working fluid
Implementation Method 4
The increase in temperature of the working fluid in the liquid zone can therefore produce evaporation of the latter
Implementation Method 5
adapted to extract heat from a hot source and to restore this heat to a cold source
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
The invention relates to a heat-transfer device (1) with a two-phase working fluid, comprising an evaporator (2) having a liquid zone (21) and a vapour zone (22); a condenser (3); a first communication circuit (11) connecting the vapour zone (22) of the evaporator (2) to the condenser (3); a second communication circuit (12) connecting at least the condenser (3) to the liquid zone (21) of the evaporator (2); a tank (4) containing working fluid; an energy supply element (5), selectively controlled, capable of increasing the pressure of the working fluid contained in the tank (4), the tank being connected only to the liquid zone (21) of the evaporator (2) via a third communication circuit (13) for working fluid substantially in liquid phase, a portion of the third communication circuit being thermally coupled to a first cold source (6).