Push-pull counter flow heat exchanger
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Solution Overview
Problem
Agrifood industry ventilation systems face challenges in high moisture and contaminated environments, leading to performance losses, high heating costs, and issues with dust and ice formation, which existing heat exchangers struggle to address effectively.
Innovation Solution
A novel heat exchanger assembly featuring a dual flow axial vane impeller with a concentric counter flow design, incorporating two vane stators for improved swirl recovery and static pressure, along with a centrally located motor for enhanced cooling and noise reduction, and a shutter system to manage air flow and contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high venting flow is used to evacuate heat, moisture and contaminants, then ventilation performance is improved, but heating costs increase
Solution Approach 1:
The heat exchanger recovers thermal energy from the exhaust air stream and transfers it to the incoming fresh air. The counter-flow arrangement allows heat exchange between the warm contaminated air being evacuated and the cold fresh air entering the building, thereby reducing the heating load while maintaining high venting flow rates.
Solution Approach 2:
The contaminated warm exhaust air, which would normally be discarded as waste heat, is instead utilized as a heat source to preheat the incoming fresh air. This converts the harmful waste heat into a beneficial resource that reduces energy consumption for heating.
2Reliability
If conventional heat exchangers are used in high moisture environments, then heat exchange function is provided, but dust clogging and ice formation occur
Solution Approach 1:
The heat exchanger is positioned in the exhaust air stream where the air is warmer and less prone to condensation and ice formation. By extracting the heat exchange function from the fresh air intake path and placing it in the exhaust path, the harmful effects of moisture and ice are avoided while maintaining heat recovery capability.
Solution Approach 2:
The heat exchanger is specifically located in the exhaust air stream where local conditions (higher temperature, lower humidity) are more favorable for reliable operation. This local placement avoids the problematic cold and moist conditions that affect conventional heat exchangers positioned near fresh air intakes.
3Ease of operation
If motor is located inside the building for easy access, then maintenance is simplified, but motor cooling efficiency decreases and noise increases
Solution Approach 1:
The motor is nested within the heat exchanger assembly in the exhaust air stream. The exhaust air acts as a cooling medium for the motor, and the motor is positioned such that it benefits from the thermal environment created by the heat exchange process while remaining accessible for maintenance.
Solution Approach 2:
The exhaust air stream serves as an intermediary cooling medium for the motor. Instead of requiring separate cooling systems or placement in locations with optimal cooling conditions, the motor utilizes the exhaust air itself as a cooling agent, transferring heat from the motor to the exhaust stream.
4Ease of manufacture
If standard fan design is used, then manufacturing is simple, but swirl friction losses reduce ventilation efficiency
Solution Approach 1:
The fan blades are designed with optimized curved geometries that reduce swirl and turbulence in the air flow. The curved blade profiles are shaped to guide the air more smoothly, reducing rotational components of velocity that would otherwise result in friction losses and reduced ventilation efficiency.
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 enhances ventilation performance, reduces energy losses, minimizes moisture formation, and extends the heat exchanger's operational lifespan by improving heat recovery and reducing noise, while being cost-effective and adaptable for various installations.
Implementation Method 1
concentric counter flow heat exchange to allow the mitigation of the moisture through isolation of the incoming cold air
Implementation Method 2
heat transfer in the exchanger core
Implementation Method 3
axial vane dual flow impeller in a venting or fan modulus
Implementation Method 4
two (2) vane stators which induce better flow swirl recovery when compared to prior art or standard design
Implementation Method 5
isolation of the incoming cold air as the incoming cold air is contained in the inner most conduit isolated by the outer most conduit
Implementation Method 6
improving cooling of the heat exchanger motor through thermal exchange from the inner conduit incoming outside air surrounding the motor
Implementation Method 7
reducing conduction lost and the need of conventional insulation from the fan unit itself
Data Source
AI summary
A Heat Exchanger Unit comprising a venting unit, a shutter, a counter flow heat exchanger and a plurality of plenums. The venting unit pulls the outside air, or fresh/purer air, from outdoor through the shutter while it pushes the exhausted inside air through the counter flow heat exchanger and the plurality of plenums toward outside air.