Microchannel Heat Exchanger Layout for Part-Load Cooling
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Solution Overview
Problem
In cooling systems with multiple compressors, the face-split and row-split configurations of microchannel heat exchangers lead to inefficiencies, such as wasted airflow when one compressor is turned off and uneven heat transfer due to temperature differences between heat exchangers.
Innovation Solution
The microchannel heat exchangers are arranged one in front of the other along the airflow direction, with each heat exchanger shared by both compressors and divided into sections by partitioning baffles, allowing refrigerant from both compressors to flow through the heat exchanger at the front, and using overlapping pipes to interconnect them, ensuring active heat transfer even when one compressor is shut off.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If face-split configuration is used with dedicated heat exchangers for each compressor, then each compressor has its own heat exchanger, but airflow cannot be reduced when one compressor is turned off, reducing system efficiency
Solution Approach 1:
The patent merges the heat exchanger functions by positioning both heat exchangers in a shared airflow path rather than having separate dedicated paths. The first and second heat exchangers are arranged sequentially in the same airflow stream, allowing the airflow to serve both heat exchangers simultaneously. This combining approach ensures that when one compressor is off, the airflow still passes through both heat exchanger units, eliminating wasted airflow and improving system efficiency during part-load operation.
2Speed
If row-split configuration is used with heat exchangers arranged one in front of the other, then airflow direction is optimized, but the front heat exchanger experiences more heat transfer than the back one due to temperature differences, reducing system efficiency
Solution Approach 1:
The patent applies local quality by having each heat exchanger handle refrigerant from a specific compressor (first heat exchanger for first compressor, second heat exchanger for second compressor) while both being exposed to the same airflow conditions. This localized assignment of refrigerant sources to specific heat exchanger positions ensures that each heat exchanger operates with refrigerant at similar temperatures and pressures, balancing the heat transfer load across both units and preventing the uneven heat transfer that would occur if a single heat exchanger handled all refrigerant.
3Ease of operation
If dedicated heat exchangers are used for each compressor, then compressor independence is maintained, but system efficiency decreases during part-load operation
Solution Approach 1:
The patent implements universality by designing a shared airflow path that serves both heat exchangers simultaneously. The single airflow stream functions for both the first heat exchanger (handling first compressor refrigerant) and the second heat exchanger (handling second compressor refrigerant), making the airflow system multi-functional. This allows the system to maintain compressor independence while improving part-load efficiency, as the airflow is actively utilized by both heat exchangers regardless of which compressors are operating.
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 improves system efficiency by utilizing airflow and heat transfer across the entire face of the heat exchanger, even during part-load operations, and reduces energy consumption by allowing airflow to be actively used across the entire heat exchanger surface.
Implementation Method 1
The refrigerant enters the low side heat exchanger and absorbs heat from the air surrounding the heat exchanger, thereby cooling the air
Implementation Method 2
The high side heat exchanger removes heat from the refrigerant
Data Source
AI summary
An apparatus includes first and second microchannel heat exchangers and first and second pipes. The first heat exchanger includes a first inlet, a second inlet, a first tube, a second tube, a first outlet, and a second outlet. Refrigerant at the first inlet is directed through the first tube to the first outlet and the first pipe. Refrigerant at the second inlet is directed through the second tube to the second outlet and the second pipe. The second heat exchanger includes a third inlet, a fourth inlet, a third tube, a fourth tube, a third outlet, and a fourth outlet. The third inlet directs refrigerant from the first pipe through the third tube towards the third outlet. The fourth inlet directs the refrigerant from the second pipe through the fourth tube towards the fourth outlet. The first pipe overlaps the second pipe between the two heat exchangers.