Heat Medium Relay Circuit for Leak-Safe Building Air Conditioning
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Solution Overview
Problem
Conventional air-conditioning apparatuses for buildings face issues such as refrigerant leakage into indoor spaces, high energy consumption due to long heat medium circulation paths, complex and costly configurations, and maintenance challenges, particularly with heat medium flow control devices malfunctioning, which can suspend operation of all indoor units.
Innovation Solution
An air-conditioning apparatus with a refrigerant circuit and a heat medium circuit that allows for selective communication of heat exchangers and flow control, using a heat medium relay unit to shorten circulation paths and prevent refrigerant leakage, and incorporating on-off devices and backflow prevention to enable maintenance without suspending all indoor units.
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 into indoor spaces occurs
Solution Approach 1:
The system divides the refrigerant circulation path from the heat medium circulation path. The refrigerant circuit remains confined to the outdoor unit while the heat medium circuit extends to indoor units, creating separate functional zones that eliminate refrigerant leakage risks in indoor spaces.
Solution Approach 2:
A heat medium (water or brine) is introduced as an intermediary substance between the refrigerant and the indoor environment. The heat medium absorbs heat from the refrigerant in the outdoor unit and transports it to indoor units, serving as a safe intermediary that does not pose leakage risks.
2Adaptability or versatility
If heat medium circulation path is extended to reach indoor units, then cooling and heating functions are achieved, but energy consumption increases due to long circulation paths
Solution Approach 1:
The heat medium relay unit acts as an intermediary station that optimizes heat medium circulation. It positions heat exchangers strategically to minimize circulation path length while still enabling heat transfer to multiple indoor units, reducing the energy required for heat medium pumping.
Solution Approach 2:
Multiple heat exchangers are combined in the outdoor unit to serve multiple indoor units simultaneously. This consolidation reduces the total circulation path length compared to having separate heat exchangers at each indoor unit, thereby reducing energy consumption.
3Adaptability or versatility
If four water pipings are arranged to allow free selection of cooling and heating in each indoor unit, then operational flexibility is achieved, but construction complexity increases
Solution Approach 1:
The system segments the piping requirements by separating the refrigerant circuit (two pipes) from the heat medium circuit (two pipes). This segmentation reduces the total number of pipes from four to two, simplifying construction while maintaining operational flexibility through the heat medium relay unit's flow control capabilities.
4Temperature
If heat exchanger is disposed near each indoor unit, then heat transfer efficiency is improved, but refrigerant leakage risk to indoor spaces cannot be eliminated
Solution Approach 1:
The system segments the heat exchange function from the refrigerant containment. Heat exchangers are placed in the outdoor unit where refrigerant is safely contained, while heat transfer to indoor units is achieved through the heat medium circuit, eliminating refrigerant leakage risk while maintaining heat transfer efficiency.
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
The solution prevents refrigerant penetration into indoor spaces, reduces energy consumption, simplifies construction, and allows for maintenance of individual indoor units during operation, enhancing safety and maintainability.
Implementation Method 1
a heat exchanger that exchanges heat between the heat source side refrigerant and a heat medium different to the heat source side refrigerant
Implementation Method 2
a circuit through which the heat medium is made to circulate, the heat medium circuit connecting the heat exchanger, a pump, and use side heat exchangers
Implementation Method 3
a refrigerant circuit that is a circuit through which a heat source side refrigerant flows
Data Source
AI summary
An air-conditioning apparatus includes a heat medium circuit that circulates a heat medium different to the refrigerant on a heat source side. The heat medium circuit includes, for example, heat exchangers related to heat medium, use side heat exchangers, first heat medium flow switching devices and second heat medium flow switching devices that change passages of the use side heat exchangers, heat medium flow control devices that controls a heat medium amount in the corresponding use side heat exchangers. An on-off device is each provided on the upstream side of the heat medium flow control device and on the downstream side of the second heat medium flow switching device and a first backflow prevention device is each provided on the downstream side of the heat medium flow control device and on the upstream side of the first heat medium flow switching device.