Interlaced Microchannel Heat Exchangers for Part-Load HVAC Efficiency
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Solution Overview
Problem
Current air systems, including heat pump and air conditioner systems, face challenges in achieving high efficiency and performance while maintaining cost-effectiveness, particularly at partial-load conditions, and require innovative solutions to enhance heat transfer efficiency and reduce manufacturing and operational costs.
Innovation Solution
The implementation of a multi-circuit air system with interlaced microchannel heat exchangers (iMCHXs) that include multiple fluidly separated refrigerant circuits, each with its own compressor and expansion valve, allowing for selective operation of circuits to optimize heat transfer and reduce costs through a controller that manages compressor and valve operations for various modes, including defrost mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional finned heat exchanger tubes are used, then the system structure is simple and easy to manufacture, but the heat transfer ratio is lower and the system is larger and heavier
Solution Approach 1:
The heat exchanger is divided into multiple microchannel passages (e.g., 102a-102d) within a single heat exchanger body, allowing refrigerant to flow through multiple segmented paths. This segmentation increases the effective heat transfer surface area and heat transfer ratio while maintaining a compact overall structure, resolving the contradiction between heat transfer performance and structural complexity
Solution Approach 2:
The patent transitions from conventional two-dimensional finned tube structures to a multi-dimensional microchannel network within a planar heat exchanger body. Multiple passages are arranged in different planes and orientations (e.g., vertical and horizontal passages), creating a three-dimensional heat transfer architecture that maximizes heat transfer surface area within a compact footprint, thereby improving heat transfer ratio without proportionally increasing external dimensions
2Productivity
If a single refrigerant circuit is used, then the system is simpler and manufacturing costs are lower, but the system efficiency at partial-load conditions deteriorates
Solution Approach 1:
The refrigerant circuit is segmented into multiple independent circuits (first refrigerant circuit and second refrigerant circuit), each with its own compressor and expansion valve. This allows selective operation of individual circuits based on load conditions, maintaining high efficiency at partial-load by activating only the necessary number of circuits while fulling-capacity circuits remain inactive, thus improving overall system efficiency without requiring all circuits to operate simultaneously
Solution Approach 2:
The system dynamically adjusts the number of active refrigerant circuits based on instantaneous load conditions. The controller can selectively activate or deactivate compressors and expansion valves to match the cooling or heating demand, enabling the system to operate efficiently across a wide range of load conditions rather than being constrained to fixed full-load operation
3Adaptability or versatility
If multiple refrigerant circuits with different configurations are used, then the system can be optimized for different conditions, but the manufacturing cost and system complexity increase
Solution Approach 1:
Different regions or circuits of the heat exchanger system are designed with locally optimized characteristics. For example, the first and second refrigerant circuits can have different heat exchanger configurations, airflow paths, or component arrangements tailored to specific operational requirements. This local optimization enables the system to adapt to different operating conditions while maintaining a modular structure that can be manufactured using standardized processes, balancing versatility with manufacturing feasibility
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 enhances full-load and part-load efficiency, reduces manufacturing and operational costs, and increases system reliability and compactness by optimizing heat transfer and airflow, while allowing for efficient heating and cooling operations.
Implementation Method 1
heat exchanger systems and methods that include multiple interlaced microchannel heat exchangers (iMCHXs) configured to transfer heat between refrigerant and air
Implementation Method 2
transferring heat from the indoor space to the refrigerant via the evaporator and transferring heat from the refrigerant to an outdoor space via the condenser
Implementation Method 3
transferring heat from the indoor space to the refrigerant via the evaporator
Implementation Method 4
heat pump system can have a cooling mode in which the indoor heat exchanger operates as an evaporator
Implementation Method 5
transferring heat from the refrigerant to an outdoor space via the condenser
Implementation Method 6
heat pump system can have a cooling mode in which the outdoor unit operates as a condenser
Implementation Method 7
a first compressor, the first interlaced microchannel heat exchanger, a first thermal expansion valve, and the second interlaced microchannel heat exchanger
Data Source
AI summary
The disclosed technology includes an air system including a first interlaced microchannel heat exchanger and a second interlaced microchannel heat exchanger. The air system can include a plurality of fluidly separated refrigerant circuits, and each of the refrigerant circuits can be configured to flow through the first interlaced microchannel heat exchanger and the second interlaced microchannel heat exchanger. The first interlaced microchannel heat exchanger can be located indoors, and the second interlaced microchannel heat exchanger can be located outdoors. Each of the refrigerant circuits can include its own compressor and expansion valve.