Heat exchanger for a heating, ventilation, and air-conditioning system
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Solution Overview
Problem
HVAC systems face inefficiencies and increased thermal stress due to heat transfer between adjacent sections of heat exchangers, particularly during phase transitions of refrigerant, which affects system performance and size optimization.
Innovation Solution
The implementation of separated sections and headers in heat exchangers, including microchannel and round tube and plate fin designs, to minimize cross heat transfer and reduce thermal stress, while allowing multiple refrigerant circuits to utilize the entire face area for enhanced efficiency during part load conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If adjacent sections of heat exchangers are connected directly to share common refrigerant flow paths, then device complexity is reduced, but harmful heat transfer between sections increases and thermal stress on joints increases
Solution Approach 1:
The heat exchanger is divided into multiple independent sections, each with its own refrigerant flow paths and headers. These sections are separated by insulation barriers that prevent harmful heat transfer between adjacent sections while maintaining individual operational independence. This segmentation allows each section to function autonomously without being thermally coupled to neighboring sections.
2Volume of stationary object
If heat exchanger size is reduced to optimize system compactness, then space utilization improves, but thermal stress on joints increases due to concentrated heat transfer
Solution Approach 1:
By dividing the heat exchanger into multiple independent sections with insulated separations, the thermal stress that would otherwise concentrate on joints in a compact unified design is distributed across multiple isolated thermal zones. Each section manages its own thermal loads independently, preventing stress concentration at inter-section joints.
Solution Approach 2:
Thermal insulation barriers are introduced as intermediary elements between adjacent heat exchanger sections. These insulation layers act as mediators that block harmful heat transfer paths while allowing the physical structure to remain compact. The insulation prevents thermal stress from propagating across section boundaries, protecting joints from excessive thermal loading.
3Device complexity
If multiple refrigerant circuits share common headers, then device complexity is reduced, but heat transfer between circuits increases during phase transitions
Solution Approach 1:
Each refrigerant circuit is assigned to its own dedicated section with independent headers, eliminating shared thermal pathways between circuits. The insulation barriers between sections prevent heat transfer from one circuit to another, ensuring that each circuit operates thermally independently while maintaining manageable system complexity through modular organization.
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, reduces size, and minimizes thermal stress on joints, enabling more effective heat exchange and operation under varying load conditions.
Implementation Method 1
designed to transfer heat between the circulating refrigerant and flowing ambient air
Implementation Method 2
a fluid transitioning from gas to liquid releases heat, while a fluid transitioning from liquid to gas absorbs heat
Implementation Method 3
a fluid transitioning from liquid to gas absorbs heat
Implementation Method 4
a fluid transitioning from gas to liquid releases heat
Data Source
AI summary
An HVAC system for use with a first refrigerant and a second refrigerant. The HVAC system may include a first refrigerant circuit for use with the first refrigerant, a second refrigerant circuit for use with the second refrigerant, and a heat exchanger. The first refrigerant circuit and the second refrigerant circuit may each include may include a compressor, an expansion device, and an evaporator. The compressor may include a first upper section, a first lower section, a second upper section in fluid communication with the first lower section, and a second lower section in fluid communication with the first upper section. The first upper section, the first lower section, the second upper section, and the second lower section may be arranged such that the first refrigerant and the second refrigerant both flow through a majority of a face area of condenser while remaining in two different circuits.