Mini-Slab Evaporator Circuit Extenders for Uneven Airflow
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Solution Overview
Problem
Fin-and-tube evaporator coils in cooling systems face inefficiencies due to uneven airflow distribution, leading to variations in refrigerant circuit temperatures, which result in reduced system performance and efficiency, especially in slab coil configurations where adding more refrigerant tubes to low airflow areas is challenging without affecting other circuits.
Innovation Solution
The implementation of mini-slab circuit extenders, which are fin-and-tube assemblies added to cold refrigerant circuits in low airflow areas to improve airflow distribution, ensuring that a portion of the air first flows across the mini-slab circuit extender before reaching the main refrigerant circuit, thereby enhancing temperature uniformity and system efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If more refrigerant tubes are added to low airflow areas, then airflow distribution and temperature uniformity improve, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The evaporator is divided into multiple independent refrigerant circuits, each with its own dedicated airflow path. This segmentation allows each circuit to be optimized independently for temperature uniformity without requiring complex modifications to the entire system, thereby improving temperature distribution while managing device complexity.
Solution Approach 2:
Different regions of the evaporator are designed with different numbers of refrigerant tubes and fin configurations tailored to local airflow conditions. Low airflow areas receive additional tubes and extended fin surfaces, while high airflow areas maintain standard configurations. This localized optimization achieves temperature uniformity without uniformly increasing device complexity throughout the entire evaporator.
2Temperature
If more refrigerant tubes are added to low airflow areas, then temperature uniformity improves, but manufacturing difficulty increases
Solution Approach 1:
The evaporator construction process is segmented into modular steps where refrigerant circuits are assembled and positioned in sequence. This modular approach simplifies manufacturing by breaking down the complex task of installing variable tube distributions into manageable, repeatable operations, thereby improving temperature uniformity while maintaining ease of manufacture.
Solution Approach 2:
The manufacturing process is optimized by applying different assembly procedures to different regions of the evaporator. Standardized modules are used in high airflow areas, while customized tube extensions and fin additions are applied only to low airflow regions requiring enhanced heat transfer, thus achieving temperature uniformity without significantly complicating the overall manufacturing process.
3Volume of moving object
If the evaporator has a tall, narrow configuration, then space utilization improves, but airflow distribution deteriorates
Solution Approach 1:
The tall, narrow evaporator is segmented into multiple refrigerant circuits arranged vertically, with each circuit having dedicated airflow paths and heat exchange surfaces. This segmentation ensures that air flowing through the tall evaporator has sufficient contact time and distribution with refrigerant tubes in each section, maintaining effective heat transfer despite the compact vertical configuration.
Solution Approach 2:
Different vertical sections of the evaporator are designed with locally optimized fin-and-tube configurations matched to airflow patterns at each height. Lower sections receive enhanced tube density and fin surfaces where airflow velocity is lower, while upper sections use standard configurations where airflow is stronger, thereby achieving uniform temperature distribution within the space-constrained tall, narrow form factor.
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 solution improves airflow distribution and temperature uniformity across the evaporator coil, increasing system efficiency and performance by up to 15° F temperature reduction in cold refrigerant circuits, leading to enhanced cooling capacity and reduced variations in coil circuit temperatures.
Implementation Method 1
fins affixed to the outside of the tubes. The tubes are fluidly coupled together, end to end. Refrigerant flows through the tubes and air to be cooled flows across the fins and outside of the tubes.
Implementation Method 2
air to be cooled flows across the fins and outside of the tubes
Data Source
AI summary
An evaporator for a cooling system has a slab coil having a plurality of refrigerant circuits with each refrigerant circuit being a fin-and-tube assembly that extends across the slab coil. At least one of the refrigerant circuits has a mini-slab circuit extender that has a fin-and-tube assembly that extends across only a portion of the fin-and-tube assembly of that refrigerant circuit and is disposed in front of that portion of the fin-and-tube assembly of that refrigerant circuit.