Fin Openings in Flat-Tube Heat Exchangers for Condensate Drainage
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Solution Overview
Problem
Heat exchangers with flattened heat transfer tubes face challenges in achieving high heat exchange efficiency while ensuring effective drainage due to water retention issues, as water accumulates between vertically aligned tubes, hindering smooth discharge.
Innovation Solution
The heat exchanger incorporates openings in the fins between vertically aligned heat transfer tubes, allowing airflow to pass transversely, which directs condensate water to flow downward along the openings and merge with discharged water, preventing ingress into the water retention region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If flattened heat transfer tubes are used to achieve superior heat transfer performance, then heat exchange efficiency is improved, but drainage performance deteriorates due to water accumulation between vertically aligned tubes
Solution Approach 1:
The fin is segmented by forming an opening that divides the water retention region into separate zones. This segmentation creates distinct pathways: one for water to enter the region and another for water to exit, preventing accumulation and improving drainage while preserving the flattened tube configuration for heat exchange.
Solution Approach 2:
The opening extracts or removes the water retention problem by providing a direct exit pathway. Water that would otherwise accumulate in the sealed space between flattened tubes is now channeled through the opening in the fin, allowing it to drain freely and preventing the drainage performance deterioration.
2Ease of operation
If slit-like or louver-like raised portions are formed in fins to promote water movement, then water discharge is improved, but water ingress into the water retention region is not suppressed
Solution Approach 1:
The opening is strategically positioned in a specific local region of the fin where it intersects with the water retention region. This localized modification creates a targeted water control zone that both promotes discharge and suppresses ingress, rather than modifying the entire fin structure.
Solution Approach 2:
The opening acts as an intermediary structure between the water retention region and the external environment. It mediates water flow by allowing controlled discharge while its positioning and geometry prevent uncontrolled water ingress, serving as a selective barrier and pathway.
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 configuration enhances drainage performance by promoting water discharge from the heat exchanger, maintaining high heat exchange efficiency while minimizing water retention, and optimizing airflow resistance.
Implementation Method 1
water flowing down from above a first heat transfer tube as an upper tube of the vertically aligned tubes and passing over the front edge portion of the first heat transfer tube flows downward along the edge of the opening located near the front edge portion, merges with water discharged from the water retention region, and flows downward below a second heat transfer tube as a lower tube of the vertically aligned tubes
Implementation Method 2
Heat transfer tubes having a flattened cross-sectional shape offer superior heat transfer performance compared to circular heat transfer tubes
Implementation Method 3
airflow passes between the vertically aligned heat transfer tubes in a transverse direction corresponding to the minor axis of the tubes
Data Source
Figure 1
Figure 2
Figure 3(a)~3(c)
AI summary
A heat exchanger (1) includes a plurality of fins (11) and a plurality of heat transfer tubes (12) having a flat cross-sectional shape, and is configured such that the heat transfer tubes (12) are arranged in a vertical direction. each fin (11) includes, between the vertically aligned heat transfer tubes (12), an opening (112) that extends in the vertical direction. The opening (112) is formed in a portion of a water retention region (R) of the fin (11) located between the vertically aligned heat transfer tubes (12), where a first virtual plane, a second virtual plane, and a third virtual plane overlap. The first virtual plane has upper and lower boundaries defined by a lower surface (12b) of an upper, first heat transfer tube (12), and a first virtual line (VL1) extending in the transverse direction of the heat transfer tubes (12) at a position intermediate between a lower, second heat transfer tube (12) and the first heat transfer tube (12). The second virtual plane is bounded by a second virtual line (VL2) connecting the front edge portions (12f) of the heat transfer tubes (12), and extends in a direction away from the front edge portions (12f). The third virtual plane is bounded by a third virtual line (VL3) connecting intermediate portions in the transverse direction of the heat transfer tubes (12), and extends in a direction toward the front edge portions (12f).