Air-Conditioning Bypass Layout for Pump-Down Refrigerant Storage
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Solution Overview
Problem
The existing refrigeration apparatus experiences a decrease in refrigeration capacity due to refrigerant storage in large-diameter tubes during pump down operations, and increasing refrigerant filling amounts lead to higher manufacturing costs and environmental concerns, especially with flammable refrigerants.
Innovation Solution
An air-conditioning apparatus with a refrigerant circuit that includes a compressor, heat source side heat exchanger, expansion valve, and use side heat exchanger connected by pipes, featuring a bypass system with a refrigerant storage unit and a controller for efficient refrigerant storage during pump down operations, avoiding the need for large-diameter tubes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large-diameter tube is disposed at the outlet of the heat source side heat exchanger to store refrigerant during pump down operation, then refrigerant can be stored during pump down operation, but refrigeration capacity decreases due to refrigerant storage in the large-diameter tube during cooling operation
Solution Approach 1:
The invention divides the refrigerant storage function from the main refrigerant circuit by introducing a separate bypass line with an on-off valve. This allows the large-diameter tube to store refrigerant only during pump down operation when the on-off valve closes the main line, while during cooling operation the valve opens to allow refrigerant to flow through the main line, preventing capacity loss.
Solution Approach 2:
The invention uses a dynamically controllable on-off valve to switch the refrigerant flow path between the main line and the bypass line with the large-diameter tube. This dynamic control allows the system to adapt to different operational modes (cooling vs. pump down), optimizing performance in each mode by directing refrigerant flow appropriately.
2Productivity
If the amount of filling refrigerant is increased to compensate for refrigerant stored in the large-diameter tube, then refrigeration capacity is maintained, but manufacturing cost increases and environmental impact from refrigerant leakage increases
Solution Approach 1:
By segmenting the refrigerant storage function into a separate bypass system, the invention allows the main refrigerant circuit to operate with the correct refrigerant amount for optimal cooling performance, while the bypass with large-diameter tube handles storage during pump down operation. This prevents the need to overfill the system with refrigerant.
Solution Approach 2:
The bypass line with on-off valve acts as an intermediary system that handles refrigerant storage temporarily during pump down operation, allowing the main refrigerant circuit to maintain its optimal refrigerant charge without being burdened by the storage requirements.
3Productivity
If the amount of filling refrigerant is increased to compensate for refrigerant stored in the large-diameter tube, then refrigeration capacity is maintained, but manufacturing cost increases
Solution Approach 1:
The invention segments the refrigerant management into two independent paths: the main refrigerant circuit for cooling operation and the bypass line with large-diameter tube for storage during pump down operation. This allows each component to be optimized independently, avoiding the need to oversize the entire system.
Solution Approach 2:
The bypass line serves as an intermediary storage system that temporarily holds refrigerant during pump down operation, eliminating the need to increase the refrigerant charge in the main circuit, thereby reducing manufacturing costs associated with larger refrigerant quantities.
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 suppresses refrigeration capacity decrease without increasing the refrigerant amount, reducing manufacturing costs and environmental impact from refrigerant leakage.
Implementation Method 1
the refrigerant flowing into the bypass is expanded by the second expansion valve
Implementation Method 2
heat source side heat exchanger serving as the condenser
Data Source
AI summary
Provided is an air-conditioning apparatus configured so that a decrease in a refrigeration capacity can be suppressed without increasing the amount of refrigerant with which a refrigerant circuit is filled and that refrigerant can be suitably stored during a pump down operation. The air-conditioning apparatus includes a first on-off valve provided at a pipe between an expansion valve and a use side heat exchanger, a bypass branching from a pipe between the expansion valve and the first on-off valve and connected to a pipe at a suction-side of a compressor, and a refrigerant storage unit configured to store the refrigerant having passed through the bypass. In a pump down operation in which the compressor operates with the first on-off valve being in a closed state, the refrigerant having flowed out from the heat source side heat exchanger flows into the bypass, and then, is stored in the refrigerant storage unit.