Devin-M said:
It says “based on the concept of Lorenz cycle”
“The maximum overall COP, optimum subcooling degree and discharge pressure are closely related to the temperature glide of the mixtures.”
From my readings I had gathered that “temperature glide” means when the temperature in the C02 changes in the condenser. If the C02 was losing heat entirely during the gas to liquid transition (vapor % is changing), it’s temperature would remain constant, so temperature glide is when the temperature doesn’t remain constant across the condenser (ie releasing heat while CO2 is entirely liquid or gas).
Almost. For the Lorenz cycle, there isn't just a temperature change in the condenser,
there is more than one heat pump/condenser. To put the issue another way: ordinarily you want a constant temperature with a phase transition in each heat exchanger. Due to the poor characteristics of CO2 as a refrigerant, they are mixing in with it a more traditional refrigerant, which results in a varying temperature instead of a constant temperature. This is a bad thing, not a good thing. One way to mitigate this problem is to add additional heat pumps, moving energy at different delta-Ts. You don't have this.
Devin-M said:
From my reading I had gathered that the “lorenz COP” is the COP you get when the C02 does have temperature glide, and the “carnot cop” is the COP you get when the CO2 doesn’t have temperature glide.
No. The Lorenz COP comes from combining/using multiple refrigerant cycles. It helps
reduce the downside of the temperature glide by having separate cycles for the different temperatures. The paper describes a system with two heat pumps working together.
None of this has anything to do with your cycle, though. Your system only has one heat pump. You're taking bits and pieces of papers about cycles that aren't the same as yours and mis-applying them. You really need to go back to the basic principles and analyze your cycle for what it is, according to those principles:
- What is the temperature at the outlet of your compressor? If that temperature needs to be higher, does that help or hurt your efficiency? In other words, does it increase or decrease the compressor input power?
- What is the temperature of the Stirling engine working fluid? If this temperature is lowered, does that help or hurt your efficiency? In other words, does it increase or decrease the power output of the Stirling engine?
The answers to these questions and implications for your idea should be obvious. The problem you are having - not knowing what temperatures to use in the equations - is part of the reason I prefer using energy to calculate efficiency. It's obvious what the input and output states are at the compressor. There's no way to accidentally use the wrong state.
But still; you're attempting to use an equation meant to be applied to an infinite series of heat pumps. Clearly, you don't have that.
P.S. I still have my college thermodynamics book. It doesn't mention Lorenz cycles. I hade to google that. To me, what Lorenz did is more of a mathematical curiosity than a useful/real-world concept. It seems that it is being resurrected - sort of - as a way to help mitigate performance/efficiency problems with new refrigerants.