Microchannel Heat Exchanger Layout Using Dead Tubes
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Solution Overview
Problem
Existing HVAC systems face challenges in thermal cross-conduction, corrosion, and mechanical protection of the heat exchanger, with existing HVAC systems failing to efficiently address these issues.
Innovation Solution
The HVAC system incorporates a microchannel heat exchanger with strategically positioned dead tubes that are not in fluid communication with the first and second manifold, and the tubes are connected to convey refrigerant between the first and second manifold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If dead tubes are added to the heat exchanger array, then thermal cross-conduction between tubes is reduced, but device complexity increases
Solution Approach 1:
Dead tubes are introduced as intermediary elements between live tubes in the heat exchanger array. These dead tubes do not convey refrigerant but serve as thermal barriers that interrupt heat transfer pathways between adjacent live tubes, thereby reducing thermal cross-conduction losses.
Solution Approach 2:
The dead tubes are simple, inexpensive structural elements that are integrated into the heat exchanger array. Although they do not perform active heat transfer functions, their low cost and simple construction allow them to be added without significantly increasing overall system complexity or cost.
2Strength
If dead tubes are positioned at heat exchanger ends, then mechanical protection to live tubes is improved, but device complexity increases
Solution Approach 1:
The dead tubes positioned at the ends of the heat exchanger array serve multiple functions: they provide mechanical protection to the live tubes from external impacts, maintain the structural integrity of the tube array, and continue to act as thermal barriers. This multi-functionality reduces the need for separate protective components.
Solution Approach 2:
The protective function is merged with the thermal barrier function by using the same dead tube elements for both purposes. The dead tubes at the ends simultaneously protect live tubes mechanically and prevent thermal cross-conduction, eliminating the need for separate protective structures.
3Reliability
If dead tubes are added to reduce corrosion, then reliability of heat exchanger is improved, but device complexity increases
Solution Approach 1:
Dead tubes serve as intermediary sacrificial elements that are more susceptible to corrosion than the live tubes. By positioning dead tubes at strategic locations, they absorb corrosive effects and protect the live tubes that are critical for refrigerant flow, thereby improving overall system reliability.
Solution Approach 2:
The dead tubes provide beforehand cushioning against corrosion by being positioned in locations where corrosion is most likely to occur. This proactive placement creates a protective buffer that shields the critical live tubes from corrosive environmental factors before damage can occur.
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 efficacy of the HVAC system is enhanced by reducing thermal cross-conduction, corrosion, and mechanical stress through the use of dead tubes in the microchannel heat exchanger, improving efficiency and reliability.
Implementation Method 1
a fluid transitioning from liquid to gas absorbs heat
Implementation Method 2
absorbs heat from one location
Implementation Method 3
a fluid transitioning from gas to liquid releases heat
Implementation Method 4
releases heat to the other
Implementation Method 5
designed to transfer heat between the circulating refrigerant and flowing ambient air
Implementation Method 6
flowing ambient air
Data Source
AI summary
An HVAC heat exchanger with an array of tubes including one or more dead tubes is provided. In one embodiment, the heat exchanger is a microchannel heat exchanger operable to exchange heat with air in an HVAC system via refrigerant passing through the microchannel heat exchanger. The microchannel heat exchanger includes an array of flat tubes arranged between a first manifold and a second manifold. The array of flat tubes includes multiple tubes coupled in fluid communication with the first manifold and the second manifold to convey refrigerant between the first manifold and the second manifold through microchannels of the multiple tubes. The array of flat tubes also includes one or more dead tubes that do not convey refrigerant between the first manifold and the second manifold. Additional systems, devices, and methods are also disclosed.