[Help] MRC mixed refrigeration: the temperature of the cold box fluctuates back and forth
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The MRC mixed refrigeration system using methane, nitrogen, ethylene, isopentane, and propane features two-stage cooling in the cryogenic tank; when the opening of the pre-cooling valve is reduced, the temperature in the pre-cooling section of the tank rises, while the depth of cryogenization decreases； When the opening of the cryogenic valve is reduced, the temperature in the cryogenic section rises, and the pre-cooling temperature decreases ； One thing increases while another decreases; what is the reason for this? Help!
It’s difficult to determine due to differences in the processes involved. Firstly, there is throttling for cooling, and then there are different locations where throttling cooling takes place in the liquid and gas phases; moreover, the locations where the refrigerant components are cooled also vary. For example, if the nitrogen component is present in lower amounts, the temperature in the middle section will be lower while the temperature in the lower section will be higher
Thank you! For small-scale units, the refrigerant is adjusted based on experience! Even with different components and different cold boxes, the same phenomenon can occur! It goes beyond ordinary understanding; I don’t know what the basis for it is
The pre-cooling valve is closed, but the work done by the compressor does not decrease. As the flow rate through pre-cooling decreases, the pressure at the compressor outlet rises. The pressure in front of the gas phase valve also increases; since the opening degree of the gas phase valve remains unchanged, the flow rate of the refrigerant passing through it increases when the pressure is high, which results in more cooling capacity and a lower temperature. Additionally, a higher pressure leads to a lower temperature after throttling.
The liquid-related factor is small, so the exhaust pressure does not increase significantly! It shouldn’t be the main reason
In my opinion, for hybrid refrigeration, it is very important to ensure proper utilization of the waste heat among the various components, as the conditions vary significantly among different devices.
It is likely due to insufficient coolant or improper distribution of the coolant; as for which specific component is the problem, it depends on the temperature gradient pattern within your cryogenic tank
I feel like there isn’t enough refrigerant.