Fluid flow reversing device for heat exchangers
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Solution Overview
Problem
HVACR systems face inefficiencies when transitioning from cooling to heating cycles due to reversed working fluid flow directions, leading to lower performance, higher power consumption, and limited leaving water temperature, as the process fluid flow direction is no longer counter to the working fluid flow direction, resulting in a lower logarithmic average temperature difference.
Innovation Solution
A flow reversing device using four two-way flow control devices to switch or reverse the process fluid flow direction without significantly altering the system's structure, achieving efficient counter-direction flow in both cycles at a lower cost compared to traditional four-way valves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the working fluid flow direction is reversed when transitioning from cooling to heating cycle, then the heating function is achieved, but the process fluid flow direction is no longer counter to the working fluid flow direction, resulting in lower heat exchange efficiency
Solution Approach 1:
The patent segments the flow control function into multiple independent two-way flow control devices (first, second, third, and fourth flow control devices) positioned at different locations in the heat exchanger system. Each device independently controls flow direction at its location, allowing the process fluid to maintain counter-directional flow relative to the working fluid throughout the heat exchanger, thereby preserving heat exchange efficiency while enabling heating operation.
Solution Approach 2:
The patent introduces a new dimension of control by using multiple flow control devices distributed at different spatial locations (inlet, outlet, and intermediate positions) rather than a single control point. This multi-point control approach enables independent manipulation of flow paths in different sections of the system, allowing simultaneous achievement of heating function and optimal counter-current flow configuration.
2Adaptability or versatility
If a traditional four-way valve is used to switch process fluid flow direction, then the flow direction can be changed, but the cost is relatively high
Solution Approach 1:
The patent divides the single four-way valve function into multiple simpler two-way flow control devices. Each two-way valve is structurally simpler and less expensive to manufacture than a four-way valve. By distributing these simpler components at multiple locations, the system achieves the same flow direction switching capability while reducing overall cost and improving manufacturability.
Solution Approach 2:
The patent replaces the expensive four-way valve with multiple cheaper two-way flow control devices. The two-way valves are simpler in structure, use fewer materials, and are more economical to manufacture. While the total number of valve components increases, the overall cost is reduced due to the lower individual component cost and simplified valve design.
3Device complexity
If the process fluid flow direction is not reversed when transitioning to heating cycle, then the system structure remains simple, but the logarithmic average temperature difference decreases, resulting in lower coefficient of performance and higher power consumption
Solution Approach 1:
The patent segments the flow control into multiple independent two-way valves positioned at strategic locations (inlet, outlet, and intermediate sections). This segmented control enables the process fluid to flow in the opposite direction relative to the working fluid in the heat exchanger during heating mode, maintaining a large logarithmic average temperature difference and improving coefficient of performance, while keeping each individual valve simple in structure.
Solution Approach 2:
The patent implements dynamic flow direction control by using independently controllable two-way valves that can switch flow paths based on operational requirements. During heating mode, the valves are configured to reverse process fluid flow direction relative to cooling mode, dynamically adapting the flow configuration to maintain optimal temperature difference and energy efficiency throughout the heating cycle.
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 provides efficient heat exchange by maintaining counter-direction fluid flow in both cycles, reducing costs and pressure drop while simplifying the system structure, thus enhancing performance and energy efficiency.
Implementation Method 1
A first port of the first flow control device and a first port of the third flow control device connect to a fluid inlet. A second port of the first flow control device and a second port of the second flow control device connect to a first port of the heat exchanger.
Data Source
AI summary
A flow reversing device is provided for a heating, ventilation, air conditioning, and refrigeration (HVACR) system having a heat exchanger. The flow reversing device included a first flow control device, a second flow control device, a third flow control device, and a fourth flow control device, each flow control device being a two-way flow control device. When the first flow control device and the fourth flow control device are opened and the second flow control device and the third flow control device are closed, a first flow is formed. When the second flow control device and the third flow control device are opened and the first flow control device and the fourth flow control device are closed, a second flow is formed. The first flow and the second flow are in opposite directions.