Auxiliary Heat Exchanger Bypass for Low-Temperature Heating Capacity
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Solution Overview
Problem
Existing air-conditioning apparatuses face challenges in maintaining heating capacity at low outdoor temperatures, particularly below -15°C, due to low heat transfer efficiency and pressure losses caused by check valves, leading to reduced capacity and compressor protection issues.
Innovation Solution
The proposed air-conditioning apparatus incorporates a refrigerant circuit with a gas extension piping, liquid extension piping, and bypass valves, along with an auxiliary heat exchanger using an external heat source, to control refrigerant flow and increase evaporating temperature, ensuring continuous heating operation even at low outdoor temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If refrigerant injection is performed into the compressor to maintain heating capacity under low outdoor temperature, then heating capacity is improved, but discharge temperature increases and compressor protection is hindered
Solution Approach 1:
The patent introduces an auxiliary heat exchanger as an intermediary component that provides additional heating capacity through a separate refrigerant circulation path. This allows the main compressor to operate at reduced load while meeting total heating demands, thereby preventing excessive discharge temperatures while maintaining required heating capacity.
Solution Approach 2:
The heating system is segmented into two independent paths: the main refrigerant circulation path through the compressor and heat exchangers, and an auxiliary heating path through the auxiliary heat exchanger. This segmentation allows the auxiliary path to承担 (bear) part of the heating load, reducing the burden on the main compressor and preventing overheating.
2Power
If outdoor air temperature drops below -15°C, then heating demand increases, but evaporating temperature becomes too low and compressor operation is hindered
Solution Approach 1:
The auxiliary heat exchanger serves as a mediator that provides heating capacity without requiring the compressor to operate at extremely low evaporating temperatures. By offloading part of the heating demand to the auxiliary path, the main system can maintain reliable compressor operation even when outdoor temperatures drop below -15°C.
Solution Approach 2:
The system changes operational parameters by introducing a parallel auxiliary heating path that operates independently of the main compressor's evaporating temperature constraints. This allows the main system to maintain reliable compressor operation while the auxiliary path supplements heating capacity under extreme cold conditions.
3Ease of operation
If check valve is provided in the passage to control refrigerant flow, then flow control is improved, but pressure loss increases and capacity is reduced
Solution Approach 1:
The auxiliary heat exchanger acts as an intermediary pathway that bypasses the need for additional check valves in the main circulation path. By providing an alternative route for achieving flow control and heat transfer, the system minimizes pressure losses associated with multiple valve components while maintaining operational 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 heating capacity by increasing refrigerant circulation and evaporating temperature, allowing for efficient heating operations at low outdoor temperatures while avoiding compressor discharge temperature rises.
Implementation Method 1
an auxiliary heat exchanger with a different heat source for heating to a heat source of the refrigerant, the auxiliary heat exchanger functioning as an evaporator that heats the refrigerant flowing in the first bypass during the heating operation
Implementation Method 2
a liquid piping expansion valve being provided midway of the liquid extension piping, the liquid piping expansion valve being capable of controlling a throughput of the refrigerant
Data Source
AI summary
An air-conditioning apparatus including a check valve in a passage between a first flow switching device and a suction side of a compressor, an expansion valve midway of a liquid extension piping, and an additional unit having a first bypass and a second bypass that are branched off from a passage between an indoor unit and the liquid expansion valve, and are connected to a passage between the check valve and the suction side of the compressor. The first bypass has, midway thereof, a first bypass expansion valve capable of controlling a throughput of refrigerant and an auxiliary heat exchanger that has a heat source different from the refrigerant, the auxiliary heat exchanger functioning as an evaporator heating the refrigerant flowing in the first bypass. The second bypass has, midway thereof, a second bypass expansion valve capable of controlling a throughput of refrigerant.