I normally read the terms viz. charged pressure and mean pressure while browsing cryocoolers research papers. I do not understand what is the actual difference between them? How do both differ while using it in numerical simulation of cryocooler?
Well. Strictly speaking, the charge pressure is the average pressure when the whole system is at room temperature. As the temperature goes down, the average pressure will decrease. This is the difference. For simulation of the cryocoolers, normally we directly use the average pressure. Certainly, as the cooler warms up, the average pressure will go up.
Well. Strictly speaking, the charge pressure is the average pressure when the whole system is at room temperature. As the temperature goes down, the average pressure will decrease. This is the difference. For simulation of the cryocoolers, normally we directly use the average pressure. Certainly, as the cooler warms up, the average pressure will go up.
the charge pressure is the working fluid pressure at rest. this determines the quantity of the fluid in the hermetically sealed cryocooler. I am familiar with Stirling engine used as a cryocooler and in like all Stirling engines, the confined space is charged with a working fluid (Helium) to certain pressure (example, 20bar) at ambient conditions. when the engine is in operation then the conditions of the working fluid in the engine change and it pressure fluctuates between a min and a max and the average of the two gives the average working pressure
There is another issue - in free piston machines you often get a pumping effect which can change the average pressure in front of the piston.
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