Counterflow Ventilation Heat Exchanger With Constricted Pipe Bundle
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Solution Overview
Problem
Current air-to-air heat exchangers for ventilation systems are complex and costly to produce, with a need for design improvements to enhance efficiency and cost-effectiveness.
Innovation Solution
The air-to-air heat exchanger features straight parallel pipes with polygonal end elements and a cylindrical insulating insert that constricts the flow, allowing countercurrent air to circulate freely and improve heat transfer, while simplifying the design and reducing production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If cross-flow heat exchangers or rotary heat exchangers are used, then heat recovery efficiency is improved, but device complexity and production cost increase
Solution Approach 1:
The heat exchanger is segmented into distinct functional zones: an inner ring for exhaust air flow, an outer ring for supply air flow, and a central pipe bundle for heat transfer. This segmentation allows simple cylindrical geometry without complex rotating parts or intricate flow paths, achieving efficient heat recovery through straightforward counterflow design.
Solution Approach 2:
Instead of using complex cross-flow or rotary mechanisms, the patent inverts the approach by using a simple cylindrical structure with concentric rings where air flows move in opposite directions through different radial zones. This inversion of the conventional heat exchanger design eliminates mechanical complexity while maintaining thermal efficiency.
2Loss of energy
If the housing inner diameter is reduced for thermal insulation, then thermal insulation performance is improved, but flow cross-section and air flow capacity decrease
Solution Approach 1:
The patent resolves the contradiction by transitioning from a single-dimension concern (housing diameter affecting both insulation and flow) to a multi-dimensional solution using concentric rings. The inner ring handles exhaust air while the outer ring handles supply air, allowing thermal insulation in the radial dimension without compromising flow capacity, as each ring maintains its own flow path.
3Ease of manufacture
If straight parallel pipes are used instead of complex pipe arrangements, then manufacturing cost and simplicity are improved, but heat transfer efficiency may be reduced
Solution Approach 1:
The pipe bundle is pre-assembled with uniform spacing and secure mounting before installation in the heat exchanger. This preliminary arrangement ensures optimal heat transfer surface area utilization and uniform air flow distribution across all pipes, maximizing heat transfer efficiency of the simple straight parallel configuration without requiring complex individual pipe routing.
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 results in a more efficient and cost-effective heat exchanger that maintains or exceeds the performance of existing designs, with improved thermal and potential acoustic insulation, and reduced energy losses.
Implementation Method 1
The insulating insert reduces the inner diameter of the housing, thereby constricting the flow cross-section. The second air flow, which is directed through the outer ring, is sucked inwards by this constriction so that it necessarily circulates around the pipes
Implementation Method 2
Part of the energy content of the heated waste air is transferred to the incoming fresh air. This is generally achieved using cross-flow heat exchangers or rotary heat exchangers
Implementation Method 3
The insulating insert serves primarily for thermal insulation but may additionally function as acoustic insulation
Data Source
AI summary
Air-to-air heat exchanger for ventilation systems with two countercurrent air flows disposed inside a cylindrical housing, a first air flow circulating inside the heat exchanger inside closed pipes, while the second air flow is in spaces between the pipes and cylindrical housing, and a fan moving the countercurrent air flows and disposed at one end of the cylindrical housing, with the fan including concentric inner and outer rings separated by a wall for moving air in opposite directions, a bunch of straight, parallel pipes whose end elements at the fan side are tightly gathered together, in the end of a cylindrical wall and, on the opposite side, in the end of a cylindrical pipe fitting, and between end elements, taper into middle sections between which are spaces, and a sleeve lining the inner wall of the housing at the middle sections and constricts the inner diameter of the housing.