Parallel Return Pipe Switching for Zeotropic Air Conditioning
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Solution Overview
Problem
Air-conditioning apparatuses using zeotropic refrigerant mixtures face performance deterioration due to the need for thick pipes to reduce pressure loss during cooling operations, leading to increased refrigerant usage and inefficiencies during heating operations.
Innovation Solution
The air-conditioning apparatus features a supply pipe for refrigerant flow from a heat source unit to a heat-use unit, with multiple parallel return pipes and an opening and closing device controlled by a controller to manage refrigerant flow, maintaining counterflow in the heat-use unit and reducing the total flow passage area during heating operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If thick pipes are used to reduce pressure loss during cooling operation, then pressure loss is reduced, but refrigerant usage increases and performance deteriorates during heating operation
Solution Approach 1:
The return pipe is divided into multiple segments (first return pipe and second return pipe) that can be independently controlled. This segmentation allows the system to optimize refrigerant flow paths for different operating conditions, reducing pressure loss during cooling while controlling refrigerant usage during heating operations.
Solution Approach 2:
The patent employs dynamic control of refrigerant flow paths using opening and closing devices (valves) that adjust the configuration based on operating mode. During cooling, both return pipes are open to reduce pressure loss; during heating, the configuration is dynamically changed to limit refrigerant usage, achieving adaptive optimization.
2Loss of energy
If refrigerant flow path is optimized for cooling operation, then pressure loss is reduced, but heat exchange efficiency deteriorates during heating operation
Solution Approach 1:
The system dynamically switches between different refrigerant flow configurations based on operating mode. The opening and closing devices enable the return pipes to be fully open during cooling for reduced pressure loss, and selectively closed during heating to optimize heat exchange efficiency, achieving mode-specific optimization.
Solution Approach 2:
The patent changes the flow path configuration parameters (open/closed states of return pipes) according to operating conditions. This parameter change allows the system to optimize for pressure loss reduction during cooling while optimizing for heat exchange efficiency during heating, resolving the contradiction between these two performance metrics.
3Productivity
If counterflow is maintained in heat-use unit, then heat exchange efficiency is improved, but refrigerant flow control becomes complex
Solution Approach 1:
The return path is segmented into multiple independently controllable pipes with individual opening and closing devices. This segmentation provides granular control over refrigerant flow, enabling the system to maintain counterflow configuration for optimized heat exchange while managing the complexity through modular valve control.
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 heat exchange efficiency by maintaining counterflow in both heating and cooling operations, reducing refrigerant usage and pressure loss, and improving performance with zeotropic refrigerant mixtures.
Implementation Method 1
a heat source unit that generates a heating energy or a cooling energy and transfers the heating energy or the cooling energy to refrigerant
Implementation Method 2
a heat-use unit that causes the refrigerant to transfer the heating energy or the cooling energy transferred from the heat source unit to a heat load through heat exchange between the refrigerant and the heat load
Data Source
AI summary
An air-conditioning apparatus includes: a heat source unit that generates a heating energy or a cooling energy that is transferred to refrigerant; a heat-use unit that causes the refrigerant to transfer the heating energy or the cooling energy to a heat load through heat exchange between the refrigerant and the heat load; a plurality of return pipes arranged parallel to each other and connecting the heat source unit and the heat-use unit to allow the refrigerant to flow therein from the heat-use unit to the heat source unit; an opening and closing device provided at at least one of the return pipes to control a flow rate of refrigerant; and a controller that opens the opening and closing device in a cooling operation, and closes the opening and closing device in a heating operation.