CO2 Medium Circuit Heat Transport for Leak-Safe Indoor HVAC
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Solution Overview
Problem
Conventional chiller systems face challenges in indoor air conditioning due to the need for large installation spaces and high maintenance efforts for water pipes, and there is a risk of refrigerant leaks causing safety hazards and environmental concerns when using refrigerants with low global warming potential and zero ozone layer destruction coefficient.
Innovation Solution
A heat transport system comprising a refrigerant circuit with HFC-32 and/or HFO refrigerant and a medium circuit with carbon dioxide, utilizing a refrigerant flow path switching device and a medium flow path switching device to transfer heat between the refrigerant and outdoor air, and the heat transfer medium and indoor air, respectively, allowing for compact installation and safe operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a water circuit with large diameter pipes is installed indoors for heat exchange, then heat exchange efficiency is improved, but installation space requirement increases and maintenance effort increases
Solution Approach 1:
The patent introduces a medium circuit with carbon dioxide as an intermediary between the refrigerant circuit and the indoor air heat exchangers. The carbon dioxide medium circuit uses smaller diameter pipes compared to water circuits, reducing installation space requirements while maintaining effective heat exchange. The medium heat exchanger acts as an intermediary component that transfers heat between the refrigerant and the carbon dioxide medium.
2Area of stationary object
If a refrigerant heat exchanger is disposed indoors to eliminate water pipes, then installation space is reduced, but refrigerant leakage risk increases causing safety hazards
Solution Approach 1:
The patent introduces a carbon dioxide medium circuit as an intermediary that is disposed indoors instead of the refrigerant circuit. The medium circuit with carbon dioxide pipes is separated from the refrigerant circuit, which remains outdoors. This intermediary approach allows the system to benefit from reduced installation space while eliminating the safety risk of combustible refrigerant leakage into the room.
Solution Approach 2:
The patent extracts the refrigerant circuit from the indoor environment and places it outdoors, while keeping the heat exchange function indoors through the medium circuit with indoor air heat exchangers. This separation takes out the hazardous refrigerant component from the indoor space, eliminating leakage risks while maintaining the cooling/heating function.
3Object-affected harmful factors
If combustible refrigerants are used to achieve low global warming potential and zero ozone layer destruction, then environmental safety is improved, but ignition accident risk increases upon leakage
Solution Approach 1:
The patent uses carbon dioxide as an intermediary medium in the medium circuit that is disposed indoors. Carbon dioxide is non-combustible and safe for indoor use. The refrigerant circuit using environmentally friendly but potentially combustible refrigerants (HFC-32 and/or HFO refrigerant) is separated and disposed outdoors, eliminating the ignition risk while maintaining environmental safety benefits.
4Temperature
If water piping is used for indoor air conditioning, then heat exchange capability is improved, but pipe diameter increases requiring larger installation space
Solution Approach 1:
The patent changes the working medium parameter from water to carbon dioxide in the medium circuit. Carbon dioxide has different thermodynamic properties that allow for smaller pipe diameters while maintaining effective heat exchange capability. This parameter change enables the system to achieve the required heat exchange performance with reduced piping dimensions.
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 system reduces the pipe diameter of the medium circuit, minimizes installation space and maintenance effort, eliminates the risk of refrigerant leaks, and meets environmental safety standards by using HFC-32 and/or HFO refrigerants and carbon dioxide, which have zero ozone layer destruction potential and low global warming potential.
Implementation Method 1
The outdoor air heat exchanger is a device for exchanging heat between the refrigerant and the outdoor air
Implementation Method 2
The medium heat exchanger is a device for exchanging heat between the refrigerant and a heat transfer medium
Implementation Method 3
The indoor air heat exchangers are devices for exchanging heat between the heat transfer medium and the indoor air
Data Source
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AI summary
A heat transport system includes a refrigerant circuit and a medium circuit. The refrigerant circuit includes a refrigerant booster, an outdoor air heat exchanger, a medium heat exchanger, and a refrigerant flow path switching device, and a fluid containing HFC-32 and/or HFO refrigerant is sealed in the refrigerant circuit as a refrigerant. The medium circuit includes a medium booster, a medium heat exchanger, a first medium flow path switching device, and a plurality of indoor air heat exchangers, and carbon dioxide is sealed in the medium circuit as a heat transfer medium.