Secondary-Loop Air Conditioning for Low Refrigerant Leakage Risk
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Solution Overview
Problem
Current air-conditioning systems face challenges in reducing refrigerant usage and preventing refrigerant leakage into room spaces, particularly when intermediate heat exchangers are placed in non-room spaces, and there is a need for standardized methods to control indoor unit capacities in water and chiller systems.
Innovation Solution
The air-conditioning apparatus separates the refrigerant circuit from the heat medium circuit, with the refrigerant circuit located outdoors and the heat medium circuit near the room space, using a compressor, refrigerant flow switching device, expansion device, and heat medium flow control units to manage refrigerant and heat medium flows, reducing the risk of refrigerant leakage and optimizing refrigerant usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If refrigerant pipes are extended to reach several hundreds of meters for multi-air-conditioning apparatuses, then the coverage area is improved, but the amount of refrigerant used significantly increases
Solution Approach 1:
The patent introduces a heat medium (water or brine) as an intermediary substance to transfer thermal energy between the refrigerant and the indoor units. The refrigerant circulates in a closed circuit within the outdoor unit, while the heat medium is pumped through pipes to indoor units, eliminating the need for extensive refrigerant piping and reducing refrigerant quantity while maintaining system coverage.
2Object-affected harmful factors
If the intermediate heat exchanger is disposed in a space such as a space above a ceiling, then the refrigerant leakage influence on room space is reduced, but refrigerant may still enter the room space if leakage occurs from pipes laid in non-room spaces
Solution Approach 1:
By using heat medium pipes instead of refrigerant pipes to connect the outdoor unit to indoor units, the patent eliminates the need for refrigerant piping through ceiling spaces and rooms. The heat medium (water/brine) is contained in a separate circulation system, so even if pipes are exposed in non-room spaces, refrigerant cannot leak into room spaces, completely preventing the harmful effect.
3Quantity of substance
If a secondary loop scheme is adopted with refrigerant circuit and heat medium circuit, then the refrigerant amount is reduced and safety is improved, but the device complexity increases
Solution Approach 1:
The patent integrates the heat medium pump, intermediate heat exchanger, and control systems into a unified outdoor unit assembly. The refrigerant circuit and heat medium circuit share common components like the compressor housing and control electronics, reducing overall system complexity despite the dual-loop configuration. This merging approach maintains safety benefits while simplifying installation and maintenance.
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 reduces the amount of refrigerant needed and minimizes refrigerant leakage into room spaces, while allowing for flexible installation and standardized control of indoor unit capacities, enhancing safety and efficiency.
Implementation Method 1
a heat medium passage of the intermediate heat exchanger, the heat medium conveying device, the heat medium flow control device, and the load-side heat exchanger communicating with each other via heat medium pipes to form a heat medium circuit, the heat medium flowing through the heat medium pipe
Implementation Method 2
an intermediate heat exchanger that transfers heating energy or cooling energy between the refrigerant and the heat medium
Data Source
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AI summary
Provided is an air-conditioning apparatus capable of reducing an amount of refrigerant being used and of preventing a leakage of the refrigerant to a room space. The air-conditioning apparatus includes an outdoor-unit casing accommodating therein a compressor, a refrigerant flow switching device, and a heat-source-side heat exchanger; a heat-medium-relay-unit casing accommodating therein an expansion device and an intermediate heat exchanger; a heat-medium-flow-control-unit casing accommodating therein a heat medium flow control device; an indoor-unit casing accommodating therein a load-side heat exchanger and an indoor air-sending device; and a heat medium conveying device configured to convey a heat medium. In the air-conditioning apparatus, the compressor, the refrigerant flow switching device, the heat-source-side heat exchanger, the expansion device, and a refrigerant passage of the intermediate heat exchanger communicate with each other via refrigerant pipes to form a refrigerant circuit, refrigerant flowing through the refrigerant pipe; and a heat medium passage of the intermediate heat exchanger, the heat medium conveying device, the heat medium flow control device, and the load-side heat exchanger communicate with each other via heat medium pipes to form a heat medium circuit, the heat medium flowing through the heat medium pipe.