Air-Conditioning Mode Switching to Reduce Refrigerant Noise
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Solution Overview
Problem
Existing air-conditioning apparatuses for buildings face issues such as refrigerant leakage, high energy consumption due to long circulation paths, complex construction requirements, and noise from refrigerant flow changes, which affect safety, efficiency, and user comfort.
Innovation Solution
The air-conditioning apparatus employs a refrigerant circuit and a heat medium circuit with a heat medium relay unit that connects the outdoor unit to indoor units using reduced piping, allowing for efficient energy transfer and operation mode switching with minimized refrigerant noise, by utilizing check valves and flow switching devices to manage refrigerant and heat medium flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If refrigerant is circulated to indoor units, then heat transfer efficiency is improved, but refrigerant leakage risk increases
Solution Approach 1:
The system divides the refrigerant circulation into two separate circuits: a heat source side circuit containing the compressor and heat source heat exchanger, and a use side circuit containing the indoor units. These circuits are connected via a heat exchanger that transfers heat between the refrigerants without direct refrigerant contact, eliminating leakage risk while maintaining heat transfer efficiency.
Solution Approach 2:
A heat exchanger serves as an intermediary between the heat source side refrigerant and the use side refrigerant. The heat source refrigerant transfers thermal energy to the use side refrigerant through the heat exchanger wall without mixing, allowing efficient heat transfer while preventing refrigerant leakage into indoor spaces.
2Reliability
If heat medium circulation path is lengthened to avoid indoor units, then refrigerant leakage risk is reduced, but energy consumption increases
Solution Approach 1:
The system segments the heat transfer function into two locations: the outdoor heat source unit where the refrigerant undergoes phase change and generates/absorbs heat, and the indoor units where only heat exchange with room air occurs. This segmentation allows the heat medium circulation path to be shortened while maintaining safety.
Solution Approach 2:
The heat exchanger in the outdoor unit acts as an intermediary that enables efficient heat transfer between the refrigerant and the heat medium in a compact space. This eliminates the need for long circulation paths, reducing energy consumption while keeping the refrigerant confined to the outdoor unit.
3Adaptability or versatility
If four water pipings are arranged for simultaneous cooling and heating, then operational flexibility is improved, but construction complexity increases
Solution Approach 1:
The heat exchanger in the outdoor unit serves multiple functions: it acts as a condenser during cooling operation and as an evaporator during heating operation. The same heat medium piping infrastructure is used for both modes, eliminating the need for separate four-piping systems while maintaining operational flexibility.
Solution Approach 2:
The system dynamically switches the function of the heat exchanger based on operational mode. By reversing the refrigerant flow direction and adjusting valve positions, the same physical infrastructure adapts to provide either cooling or heating, simplifying construction while preserving versatility.
4Use of energy by moving object
If heat exchanger is disposed near indoor units, then heat transfer efficiency is improved, but refrigerant leakage risk increases
Solution Approach 1:
The system segregates the refrigerant-containing components (compressor, heat source heat exchanger) from the indoor living spaces by placing them in the outdoor heat source unit. The indoor units contain only air-handling components, eliminating refrigerant leakage risk while maintaining efficient heat transfer through the outdoor heat exchanger.
Solution Approach 2:
The outdoor heat exchanger serves as an intermediary that enables efficient heat transfer to the indoor environment without requiring refrigerant presence inside the building. Thermal energy is transferred from the refrigerant through the heat exchanger to the heat medium, which then circulates to indoor units for final heat exchange with room air.
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 refrigerant leakage risk, minimizes energy consumption, simplifies construction, and decreases refrigerant noise during operation mode changes, enhancing safety and user comfort while maintaining efficient energy transfer.
Implementation Method 1
a heat medium relay unit 3 disposed between the outdoor unit 1 and the indoor units 2. The heat medium relay unit 3 exchanges heat between the heat source side refrigerant and the heat medium.
Implementation Method 2
The heat medium relay unit 3 is connected to the indoor units 2 with pipings 5 through which the heat medium flows.
Data Source
Figure 1
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Figure 3
AI summary
To provide an air-conditioning apparatus that reduces large refrigerant noise generated when changing an operation mode. In an air-conditioning apparatus 100, when switching to a second operation mode from a first operation mode, switching to the second operation mode is performed after a predetermined time has elapsed after controlling either or all of expansion devices, controlling either or all of second flow switching devices, and controlling either or all of a first on-off device and a second on-off device such that a pressure difference of a heat source side refrigerant before and after each of the expansion devices is smaller compared to that in an operation state of the first operation mode.