Ventilation Heat Exchanger Circuits for Cold Recovery Control
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Solution Overview
Problem
Conventional ventilation systems experience efficiency losses due to temperature shifts in heat transfer media, leading to reduced cold recovery from exhaust air and inefficient heating and cooling processes, particularly when cooling supply air results in a heat transfer medium exiting the supply air heat exchanger at too low a temperature.
Innovation Solution
A circulatory system with a pair of heat exchangers connected by a pipe and a hydraulic module, allowing for independent or coupled operation of heat transfer circuits, includes an additional heat transfer device for energy coupling, enabling efficient heat or cold energy transfer and optimizing temperature differences between the heat carrier and air flows.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the heat transfer medium is cooled before entering the supply air heat exchanger to achieve desired supply air temperature, then the supply air temperature control is improved, but the cold recovery efficiency from exhaust air is reduced
Solution Approach 1:
The heat transfer medium flow is divided into two separate circuits: a first heat transfer medium circuit passing through the exhaust air heat exchanger for cold recovery, and a second heat transfer medium circuit passing through the supply air heat exchanger for temperature control. This segmentation allows independent optimization of cold recovery efficiency and supply air temperature control without mutual interference.
Solution Approach 2:
A second heat exchanger is introduced as an intermediary device in the second heat transfer medium circuit to cool the heat transfer medium before it enters the supply air heat exchanger. This intermediary cooling device enables precise supply air temperature control while maintaining optimal temperature differences for cold recovery in the first circuit.
2Use of energy by moving object
If the heat transfer medium temperature is lowered to improve heating efficiency, then the heating performance is enhanced, but the cold recovery from exhaust air is negatively affected
Solution Approach 1:
The system segments the heat transfer medium flow into separate circuits for heating and cold recovery operations. The first circuit dedicated to cold recovery maintains optimal temperature differences with exhaust air, while the second circuit handles heating operations independently, allowing both functions to operate at peak efficiency simultaneously.
Solution Approach 2:
The dual-circuit heat transfer medium system provides multi-functionality by enabling independent optimization for both heating and cold recovery operations. Each circuit can be controlled separately to serve its specific function, making the system adaptable to different operational requirements without compromise.
3Device complexity
If a single heat transfer medium circuit is used for both heating and cooling, then the system complexity is reduced, but the efficiency loss increases due to temperature shifts
Solution Approach 1:
The heat transfer medium system is segmented into two independent circuits with separate flow paths and control mechanisms. This segmentation eliminates the efficiency losses associated with temperature shifts in a single-circuit system, as each circuit can maintain optimal temperature differences for its specific function without interference from the other.
Solution Approach 2:
Each heat transfer medium circuit is designed with local quality optimization: the first circuit is optimized for cold recovery with appropriate temperature levels for exhaust air heat exchange, while the second circuit is optimized for heating or cooling operations. This local optimization ensures maximum efficiency in each function while the overall system remains manageable.
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 cold recovery from exhaust air while maintaining control over supply air temperature, improving the coefficient of performance of the refrigeration machine and reducing energy losses, thereby increasing overall system efficiency.
Implementation Method 1
a supply air heat exchanger (LWT ZU1), which is arranged in a supply air volume flow (ZU), is coupled with an exhaust air heat exchanger (LWT AB1), which is arranged in an exhaust air volume flow (AB), in a heat transfer medium circuit (WK1)
Implementation Method 2
the heat transfer medium being able to be thermodynamically treated directly with the evaporator
Implementation Method 3
the heat transfer medium being able to be thermodynamically treated directly with the evaporator
Data Source
Figure 1
Figure 2
Figure 3~3A
AI summary
A circulation system, comprising a unit for energy coupling, has two heat exchangers (LWT ZU1, LWT ZU2) in an air inlet volume flow (ZU) and one heat exchanger (LWT AB1) in an air outlet volume flow (AB) in an air treatment system. In order to improve the energy yield, units for forming two heat carrier circuits (WK1, WK2) are provided, which can be variably interconnected for the heat exchangers (LWT ZU1, LWT ZU2, LWT AB1). In one case, all heat exchangers (LWT ZU1, LWT ZU2, LWT AB1) are connected as a circulation system (KVS). As an alternative, only one air inflow heat exchanger (LWT ZU1) and one air outflow heat exchanger (LWT AB1) are connected to the heat exchanger circuit (WK1), and a further air inflow heat exchanger (LWT ZU2) in the air inflow volume flow (ZU) is operated in a separate heat exchanger circuit (WK2).