Exhaust Air Heat Pump Recirculation for Variable Ventilation
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Solution Overview
Problem
Decentralized replacement air exhaust air heat pump systems face challenges in controllability and efficiency, particularly in multi-apartment buildings, due to varying ventilation conditions and low coefficient of performance (COP), as they rely on direct control of air flow which can disrupt indoor air quality and temperature balance across apartments.
Innovation Solution
The system incorporates a recirculation channel that returns processed air to the heat pump intake, mixing it with exhaust and outdoor air to maintain optimal operation, using adjustable valves and sensors to control the air flow ratios, ensuring efficient heat recovery and COP optimization across varying conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the system uses direct control of air flow through the heat pump, then heat recovery efficiency is improved, but indoor air quality and temperature balance across apartments deteriorate
Solution Approach 1:
The patent introduces a recirculation channel as an intermediary path that allows processed air to be returned and mixed with fresh exhaust air before entering the heat pump. This mediator mechanism enables the system to maintain high air flow through the heat pump for efficient heat recovery while preventing direct disruption to individual apartment ventilation, thus resolving the contradiction between heat recovery efficiency and indoor air quality maintenance
Solution Approach 2:
The system changes the composition parameter of the air fed to the heat pump by mixing recirculated air with fresh exhaust air. This parameter change allows the heat pump to receive sufficient air volume for efficient heat recovery while the recirculated portion helps stabilize temperature and air quality conditions across apartments, reducing the harmful effects of direct air flow control
2Productivity
If the system increases air flow through the heat pump, then heat recovery efficiency is improved, but system controllability deteriorates
Solution Approach 1:
The patent implements dynamic control by introducing adjustable valves in both the recirculation channel and the fresh air channel. These dynamic elements allow the system to adaptively control the mixing ratio of recirculated and fresh air, enabling flexible adjustment of air flow characteristics while maintaining efficient heat recovery, thus improving controllability without sacrificing productivity
3Adaptability or versatility
If the system uses recirculated air mixed with exhaust air, then system adaptability to varying conditions is improved, but device complexity increases
Solution Approach 1:
The recirculation channel serves multiple functions: it returns processed air to the mixing zone, provides a source of recirculated air for mixing with fresh exhaust air, and enables system adaptability to varying ventilation conditions. This multi-functionality allows the system to handle diverse operating conditions without requiring entirely separate systems, thus achieving versatility with manageable complexity
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 approach enhances controllability and efficiency by allowing the system to adapt to changing ventilation conditions, maintaining high COP by using recirculated and outdoor air, which can be cooler, thus optimizing heat recovery and minimizing disruptions across the building.
Implementation Method 1
a heat pump unit for recovering heat from the exhaust indoor air
Implementation Method 2
a recirculation channel capable of conveying part of air at the output of the heat pump back to the air intake of the heat pump unit mixed with the exhaust indoor air
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
The invention relates to an exhaust air heat pump apparatus (10) and method of processing exhaust air of buildings. The present apparatus comprises a first inlet channel (13) for exhaust indoor air, an outlet channel (15) for discharge air, and a heat pump unit (11) comprising an air intake connected to the first inlet channel (13) and air output connected to the outlet channel (15), the heat pump unit (11) being capable of recovering heat from or transferring heat to air provided to said air intake, whereby said discharge air is produced at the air output. According to the invention, there are further provided a second inlet channel (18) for outdoor air, the second inlet channel (18) being connected to the air intake of the heat pump unit (11) and a recirculation channel (17) capable of recirculating part of air at the output of the heat pump unit (11) back to the air intake of the heat pump unit (11). The apparatus is adapted to mix the outdoor air, the recirculated air or both of them with the exhaust indoor air before feeding to the heat pump unit (11). The invention allows for optimization of heat pump efficiency in varying conditions.