Air-Conditioning Mode Switching With Refrigerant Pressure Balancing
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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 and costly constructions, and noise from refrigerant flow changes, which affect safety, energy efficiency, and ease of construction.
Innovation Solution
The air-conditioning apparatus incorporates a refrigerant circuit with a compressor, flow switching devices, and heat exchangers, along with a heat medium circuit with pumps and flow switching devices, allowing for controlled pressure differences and operation mode switching to reduce refrigerant noise and energy consumption, while minimizing refrigerant circulation near indoor units and simplifying piping connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If refrigerant is circulated to indoor units, then cooling and heating functions are achieved, but refrigerant leakage risk increases
Solution Approach 1:
The patent introduces a heat medium (water or antifreeze solution) as an intermediary substance that carries thermal energy between the outdoor heat source unit and indoor units. This heat medium circulates through dedicated piping systems, completely isolating the refrigerant confined to the outdoor unit. The heat exchangers at indoor units transfer heat between the heat medium and indoor air, eliminating direct refrigerant exposure in living spaces while maintaining effective heating and cooling functions.
2Reliability
If heat medium circulation path is made long to avoid refrigerant in indoor units, then safety improves, but energy consumption increases
Solution Approach 1:
The system divides the thermal transfer function into two distinct segments: the outdoor heat source unit handles refrigerant-based heat generation/absorption, while indoor units handle heat delivery to/from living spaces. This segmentation allows the heat medium circulation to be optimized independently - piping is routed efficiently through building structures, and indoor units are positioned strategically to minimize circulation distance while maintaining safety requirements of keeping refrigerant outside living spaces.
3Adaptability or versatility
If four water pipings are arranged for simultaneous cooling and heating, then operational versatility improves, but construction complexity increases
Solution Approach 1:
The patent implements a dual-piping system where the same two pipes (supply and return) serve both heating and cooling functions by controlling the direction and temperature of heat medium flow. The outdoor heat source unit can operate in heating mode (providing hot water to indoor units) or cooling mode (providing cold water to indoor units), and the indoor units respond accordingly. This universal piping approach eliminates the need for separate four-pipe systems while maintaining the ability to provide both heating and cooling services.
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 noise, enhances safety by minimizing leakage risks, saves energy through shorter circulation paths, and simplifies construction by reducing piping complexity, thereby improving comfort and efficiency.
Implementation Method 1
a heat source side refrigerant and a heat medium exchanging heat in the heat exchangers related to heat medium
Implementation Method 2
controlling either or all of the expansion devices... such that a pressure difference of the heat source side refrigerant before and after each of the expansion devices is smaller
Data Source
AI summary
To provide an air-conditioning apparatus that reduces large refrigerant noise generated when changing an operation mode. In an air-conditioning apparatus, 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.