Multi-Unit Heat Exchanger Flow Reversal for Part-Load Condensing
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Solution Overview
Problem
In air-conditioning systems, part-load operations with reduced compressor frequency can lead to lower refrigerant flow velocities in heat exchangers, resulting in degraded heat exchange performance due to equal gravitational effects on refrigerant flow in all tubes.
Innovation Solution
A heat exchanger configuration where the opening-closing valve controls refrigerant flow direction between heat exchange units, allowing only some units to flow upward, maintaining required flow velocities and reducing performance degradation during part-load operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If refrigerant flows vertically upward in all flat tubes during part-load operation, then heat exchange performance is maintained, but refrigerant flow velocity becomes insufficient due to reduced compressor frequency
Solution Approach 1:
The heat exchanger is divided into multiple heat exchange units with independent refrigerant flow paths. Each unit can have refrigerant flowing in different directions (upward or downward) controlled by opening-closing valves, allowing selective optimization of flow velocity in different segments during part-load operation
Solution Approach 2:
Instead of having all refrigerant flow upward in all tubes, the invention allows some refrigerant to flow downward in selected heat exchange units. This inverted approach in certain segments enables upward-flowing units to maintain sufficient flow velocity while still achieving overall heat exchange performance
2Use of energy by moving object
If compressor operational frequency is reduced for part-load operation, then energy consumption is reduced, but refrigerant flow velocity in heat exchanger decreases
Solution Approach 1:
The refrigerant flow system is segmented into multiple independent heat exchange units, each with controllable flow direction. This allows the system to maintain adequate flow velocity in upward-flowing units even when overall compressor frequency is reduced for energy savings during part-load operation
Solution Approach 2:
The opening-closing valves dynamically adjust refrigerant flow distribution among heat exchange units based on operating conditions. During part-load operation, the system dynamically redirects flow to maintain velocity requirements while allowing compressor frequency reduction for energy 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
This configuration ensures the necessary refrigerant flow velocity is maintained in heat exchangers during part-load operations, thereby minimizing heat exchange performance degradation.
Implementation Method 1
a plurality of flat tubes spaced from and parallel to each other and in which a refrigerant flow passage is formed through which refrigerant flows in an up-down direction, a plurality of fins provided between the plurality of flat tubes adjacent to each other
Implementation Method 2
Each of the plurality of heat exchange units exchanges heat between refrigerant and air
Implementation Method 3
refrigerant in all the flat tubes is equally affected by gravity. This may generate an area with a lower refrigerant flow velocity than the required refrigerant flow velocity for refrigerant to flow upward inside the flat tubes
Data Source
AI summary
A heat exchanger includes a plurality of heat exchange units each including a plurality of flat tubes, a plurality of fins, an upper header, and a lower header. In the plurality of heat exchange units, the upper headers are connected such that the upper headers communicate with each other, and the lower headers are connected such that the lower headers communicate with each other through an opening-closing valve. The heat exchanger has a configuration in which when the heat exchanger serves as a condenser, the opening-closing valve is controlled such that refrigerant in at least one of the plurality of heat exchange units flows in an upward direction, and refrigerant in the other one or the other ones of the plurality of heat exchange units flows in a downward direction.