Refrigerant charging method for refrigeration device having carbon dioxide as refrigerant
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Solution Overview
Problem
The existing refrigerant charging methods for carbon dioxide-based refrigeration devices are inefficient, leading to increased time requirements and operational delays due to the refrigerant changing into a solid state during the charging process, causing obstruction and prolonging the system's startup time.
Innovation Solution
A refrigerant charging method that involves cooling the refrigerant container to 31° C or below before charging, ensuring the refrigerant remains in a liquid or gas phase, and using heating means to maintain a specific enthalpy of 430 kJ/kg or higher to prevent solidification, thereby minimizing obstruction and reducing charging time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the refrigerant is charged directly from a cylinder into the refrigeration system without temperature control, then the charging process is simple and fast, but the refrigerant may solidify during charging causing obstruction and delays
Solution Approach 1:
The refrigerant cylinder is pre-cooled to -10°C or lower before the charging operation begins. This preliminary cooling action ensures that the refrigerant remains in liquid phase during charging, preventing solidification and obstruction in the piping system while maintaining fast charging speed.
Solution Approach 2:
The temperature parameter of the refrigerant cylinder is controlled and changed to -10°C or lower. By changing this physical parameter, the refrigerant's phase stability is maintained during the charging process, preventing it from solidifying even when discharged into the system.
2Ease of manufacture
If conventional charging methods are used for carbon dioxide refrigerant, then the process follows standard procedures, but the refrigerant solidifies causing charging obstructions
Solution Approach 1:
The refrigerant cylinder temperature is specifically controlled to -10°C or lower, which is a parameter change from conventional methods. This modification to the temperature parameter prevents refrigerant solidification while maintaining a standardized and smooth charging process without obstructions.
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 method prevents refrigerant solidification during charging, reduces the time required for the process, and ensures quicker system startup by maintaining the refrigerant in a suitable phase, thus enhancing the efficiency and reliability of carbon dioxide refrigeration systems.
Implementation Method 1
when the specific enthalpy of the refrigerant when entering the intended charging space is less than 430 kJ/kg, an abrupt drop in the pressure can cause the refrigerant to change to a solid state
Implementation Method 2
heating means to maintain a specific enthalpy of 430 kJ/kg or higher to prevent solidification
Data Source
AI summary
A refrigerant charging method includes installing, cooling, confirming, and moving steps. In the installing step, a refrigeration device is installed on site. In the cooling step, a container is cooled to 31° C. or below using a cooling medium. In the confirming step, it is confirmed that the container has reached 31° C. or below. In the moving step, the refrigerant is moved to the intended charging space from the container upon confirming that the container has reached 31° C. or below via the cooling step. When moving the refrigerant from the container to the intended charging space, first, refrigerant that is in a gas phase within the container is moved into the intended charging space, whereupon refrigerant that is in a liquid phase within the container is moved into the intended charging space.