Heat exchanger having stacked coil sections
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Solution Overview
Problem
At high ambient air temperatures, air-cooled condensers in HVAC&R systems experience decreased performance and efficiency due to increased condensing temperatures and pressures, limiting the system's ability to maintain desired performance and efficiency.
Innovation Solution
The implementation of a heat exchanger with stacked coil sections operating at different condensing temperatures and pressures, where air flow is configured in a series arrangement to optimize heat transfer and reduce condensing temperatures, along with the use of multiple refrigerant circuits and compressors with varying volume ratios to manage compressor loads and enhance efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single condenser section is used, then the system structure is simple, but the system capacity decreases at very high ambient air temperatures
Solution Approach 1:
The condenser is divided into multiple stacked coil sections (first coil section, second coil section, third coil section) that operate at different condensing temperatures and pressures. This segmentation allows each section to handle different refrigerant loads independently, maintaining system capacity at high ambient temperatures while keeping each individual coil section relatively simple in structure.
2Reliability
If air flow is increased through the condenser, then heat exchange performance improves, but fan noise increases
Solution Approach 1:
Different coil sections are designed with different local qualities - specifically, different condensing temperatures and pressures are maintained in different sections. The first coil section operates at a higher condensing temperature than the second coil section, allowing optimized heat exchange performance in each section without requiring uniformly high air flow that would increase fan noise.
3Temperature
If the condenser operates at higher condensing temperatures, then heat exchange with ambient air is improved, but system efficiency decreases
Solution Approach 1:
The condenser is segmented into multiple sections operating at different condensing temperatures. The first coil section operates at a higher condensing temperature (better heat exchange with ambient air), while the second coil section operates at a lower condensing temperature (maintains system efficiency). This segmentation resolves the contradiction by allowing both higher and lower condensing temperatures to coexist in different parts of the system.
4Productivity
If compressor capacity is increased, then system capacity is improved, but compressor motor load becomes unbalanced
Solution Approach 1:
The refrigerant circuit is segmented into multiple independent loops, each with its own compressor (first compressor, second compressor, third compressor). Each compressor serves a specific coil section and operates independently, allowing balanced motor loads while collectively providing high system capacity. The first compressor serves the first coil section, the second compressor serves the second coil section, and the third compressor serves the third coil section.
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 results in a more compact, efficient, and cost-effective HVAC&R system with improved performance at high ambient temperatures, reduced fan noise, and increased system capacity, while maintaining lower condensing temperatures and compressor motor load balancing.
Implementation Method 1
the refrigerant vapor delivered to the condenser enters into a heat exchange relationship with a fluid, e.g., air or water
Implementation Method 2
circulating air is used for heat exchange in an air-cooled condenser
Implementation Method 3
The at least one first section is positioned next to and substantially parallel to the at least one second section and the at least one first section and the at least one second section are positioned to have the air exiting the at least one first section entering the at least one second section
Implementation Method 4
The refrigerant vapor delivered to the condenser enters into a heat exchange relationship with a fluid, e.g., air or water, and undergoes a phase change to a refrigerant liquid
Implementation Method 5
The refrigerant vapor delivered to the condenser enters into a heat exchange relationship with a fluid, e.g., air or water, and undergoes a phase change to a refrigerant liquid
Data Source
AI summary
A heat exchanger is provided with stacked coil sections. Each of the stacked coil sections is configured to circulate a fluid independent from the other coil section. An air moving device is used to circulate air through both of the stacked coil sections. The stacked coil sections are positioned to have the air exiting the one coil section entering the other coil section.