CO₂ Refrigerant Charging with Heating to Prevent Solidification
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Solution Overview
Problem
The existing refrigerant charging methods for carbon dioxide-based refrigeration devices are inefficient, leading to increased time required for charging and delayed system operation due to the refrigerant changing into a solid state (dry ice) when pressure drops abruptly during on-site charging, causing obstruction and prolonging the charging process.
Innovation Solution
Incorporating a heating or cooling mechanism between the refrigerant container and the charging space to maintain a specific enthalpy of 430 kJ/kg or higher, preventing the refrigerant from solidifying, and ensuring efficient charging by managing the temperature and pressure conditions to prevent solidification during the charging process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If refrigerant is charged using conventional vacuum pump evacuation method, then charging can be performed, but the refrigerant changes into solid state (dry ice) causing obstruction and prolonging charging time
Solution Approach 1:
The patent applies parameter changes by controlling the temperature and pressure parameters of the refrigerant during charging. Specifically, the refrigerant container is cooled to maintain refrigerant temperature below the dew point temperature corresponding to the container pressure, preventing solidification. This parameter control ensures continuous refrigerant flow while maintaining charging speed.
Solution Approach 2:
The patent implements preliminary action by pre-cooling the refrigerant container before charging begins. The cooling mechanism is activated in advance to establish appropriate temperature conditions, preventing solidification from occurring during the charging process. This preliminary preparation eliminates obstructions before they can form.
2Loss of time
If refrigerant container is cooled to prevent solidification, then charging time is reduced, but additional cooling mechanism and control are required
Solution Approach 1:
The patent applies self-service by utilizing the refrigerant's own phase change characteristics and heat transfer properties to achieve cooling. The system leverages the natural thermodynamic behavior of CO2 refrigerant during expansion and phase change to cool itself, reducing the need for external active cooling mechanisms while maintaining charging efficiency.
Solution Approach 2:
The patent introduces a cooling mechanism as an intermediary between the refrigerant container and the environment. This intermediary component mediates heat transfer to maintain appropriate temperature conditions during charging, balancing the need for temperature control with system simplicity.
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 approach significantly reduces the time required for refrigerant charging and minimizes delays in system operation by maintaining the refrigerant in a suitable state, preventing solidification and associated obstructions, thus enhancing the efficiency and reliability of the charging process.
Implementation Method 1
the refrigerant that has exited the container is heated by the heating means so that a specific enthalpy of the refrigerant when entering the intended charging space will be 430 kJ/kg or higher
Implementation Method 2
there will be incidences of faults related to, e.g., an increase in the time required for the task, or an inability for the air conditioning operation to commence for a certain period of time after charging is completed
Data Source
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AI summary
When a refrigeration device in which CO2 is used as a refrigerant is to be charged with a refrigerant, the time required for charging and the time that elapses after charging until operation can recommence can be reduced. A refrigerant charging method for an air conditioning device (10) in which carbon dioxide is used as a refrigerant comprises a connecting step and a refrigerant charging step. In the connecting step, a cylinder (81) containing the refrigerant is connected to a space in the air conditioning device 10 intended to be charged by the refrigerant, a heater (83) being interposed therebetween. In the refrigerant charging step, the refrigerant is moved to the intended charging space from the cylinder (81), via the heater (83). In the refrigerant charging step, further, the refrigerant that has exited the cylinder (81) is heated by the heater (83) so that a specific enthalpy of the refrigerant when it enters the intended charging space will be 430 kJ/kg or higher.