Compact heat recovery ventilation unit

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Solution Overview

Problem

Existing heat recovery ventilation units are not compact enough and require excessive energy to operate, leading to high air flow noise due to suboptimal air duct designs.

Innovation Solution

A compact heat recovery ventilation unit design featuring internal air flow ducts with rectangular cross sections, strategically located ventilators downstream of the heat exchanger, and an optional bypass air flow path to minimize pressure drop and noise, with a bypass valve and control unit for enhanced performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If conventional air duct designs are used in heat recovery ventilation units, then the units can handle adequate air throughput, but the units become large in size and generate excessive air flow noise

Engineering Contradiction:
Improveunit sizeVSAvoidair throughput
Core Design Contradiction:
Volume of moving objectVSProductivity

Solution Approach 1:

The patent transitions from conventional circular air ducts to rectangular air ducts, utilizing the rectangular cross-section geometry to optimize space utilization. This dimensional change allows ducts to be arranged more efficiently in three-dimensional space within the housing, achieving compact unit dimensions while maintaining adequate air throughput capacity through optimized duct sizing and positioning.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Productivity

If conventional air duct designs are used in heat recovery ventilation units, then the units can handle adequate air throughput, but excessive energy is required to drive the ventilators

Engineering Contradiction:
Improveair throughputVSAvoidenergy consumption
Core Design Contradiction:
ProductivityVSUse of energy by moving object

Solution Approach 1:

The patent applies different cross-sectional dimensions to different air flow paths within the unit. The rectangular ducts are sized and positioned to create optimized local flow characteristics for each air stream (supply air, exhaust air, fresh air, return air). This local optimization reduces flow resistance and pressure drop in critical sections, thereby reducing the energy required by ventilators while maintaining the required air throughput.

Inventive Principle:
Principle #3Local quality

3Productivity

If conventional air duct designs are used in heat recovery ventilation units, then the units can handle adequate air throughput, but excessive air flow noise is generated

Engineering Contradiction:
Improveair throughputVSAvoidair flow noise
Core Design Contradiction:
ProductivityVSObject-generated harmful factors

Solution Approach 1:

The rectangular cross-section geometry of the air ducts provides better flow control characteristics compared to circular ducts. The flat surfaces and defined edges of rectangular ducts create more predictable flow patterns and reduce turbulence-induced noise. This dimensional change allows for optimized duct transitions and connections that minimize flow separation and vortex formation, thereby reducing air flow noise while maintaining adequate throughput.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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 design achieves a compact unit with improved air throughput and reduced noise generation without sacrificing performance, allowing for efficient air handling and versatile installation options.

Implementation Method 1

a heat exchanger having first air flow passages and second air flow passages for transferring heat energy form return air entering said first air flow passages and exhaust air leaving said first air flow passages on the one hand, to outside air entering said second air flow passages and supply air leaving said second air flow passages on the other hand

Methodology Applied
Scientific EffectHeat transfer: Convection

Data Source

PatentEP2971990B1Compact heat recovery ventilation unit
Publication Date: 2019.08.28 ZEHNDER GROUP INTERNATIONAL AG
  • EP2971990B1 patent drawingFigure 1
  • EP2971990B1 patent drawingFigure 2
  • EP2971990B1 patent drawingFigure 3

AI summary

The invention relates to a ventilation unit for providing supply air to an apartment or parts thereof and for removing return air from said apartment or parts thereof, said ventilation unit comprising: a supply air outlet for establishing supply air flow communication with said apartment; a return air inlet for establishing return air flow communication with said apartment; an exhaust air outlet for establishing exhaust air flow communication with the atmosphere; an outside air inlet for establishing outside air flow communication with the atmosphere; a heat exchanger having first air flow passages and second air flow passages for transferring heat energy from return air entering said first air flow passages and exhaust air leaving said first air flow passages on the one hand, to outside air entering said second air flow passages and supply air leaving said second air flow passages on the other hand; a first ventilator at a first location within the ventilation unit, for transporting air through a first air flow path starting at said return air inlet, passing through said first air flow passages in the heat exchanger and ending at said exhaust air outlet; and a second ventilator at a second location within the ventilation unit, for transporting air through a second air flow path starting at said outside air inlet, passing through said second air flow passages in the heat exchanger and ending at said supply air outlet. According to the invention, said first air flow path and said second air flow path comprise internal air flow ducts having rectangular cross sections.