Finding mass of working fluid needed in a thermo cycle

In summary, the question is about estimating the necessary amount of working fluid for a refrigeration cycle in a cooling system for a space suit or portable life support system. The suggested method is to integrate the density, diameter, and length of the tubing, and also consider thermal effects and flexure. The question also asks if there are separate primary and secondary circuits for the refrigeration.
  • #1
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This question is related to a project.

I have the mass flow rate, RPM, and all other related information regarding a refrigeration cycle, does anyone have an idea on how can I estimate the total amount of working fluid I need to put into the device?

In case this comes up: the device is going to be a cooling system put in the space suit/portable life support system (PLSS) which involves long tubing around the cooling garment that circulates the cool fluid and a few more tubing plus a compressor and heat exchanger in the PLSS.

Thanks a lot!
 
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  • #2
You'll need to integrate ##\ \rho\; {\pi d^2 \over 4 } dl \ ## along the length of the tubing :smile:
 
  • #3
Do you have primary and secondary circuits for the refrigeration or just one circuit ?

In any case you need to allow for thermal effects and flexure .
 

1. How do I calculate the mass of working fluid needed in a thermo cycle?

To calculate the mass of working fluid needed in a thermo cycle, you will need to know the specific heat capacity of the working fluid, the initial and final temperatures, and the heat transfer in the cycle. You can then use the formula: Mass = (Heat transfer)/(Specific heat capacity x Temperature change) to find the mass of the working fluid needed.

2. What is the specific heat capacity of a working fluid?

The specific heat capacity of a working fluid is the amount of heat energy required to raise the temperature of 1 kilogram of the fluid by 1 degree Celsius. It is a characteristic property of the fluid and can be found in thermodynamic tables or through experimentation.

3. How does the initial and final temperature affect the mass of working fluid needed?

The initial and final temperature difference determines the temperature change in the cycle, which is a key factor in calculating the mass of working fluid needed. A larger temperature difference will require a larger mass of working fluid to achieve the desired heat transfer in the cycle.

4. What is the heat transfer in a thermo cycle?

The heat transfer in a thermo cycle is the amount of heat energy that is exchanged between the working fluid and its surroundings. It can be calculated using the formula: Heat transfer = Mass x Specific heat capacity x Temperature change.

5. Can I use the same mass of working fluid for different thermo cycles?

No, the mass of working fluid needed will vary for different thermo cycles depending on the specific heat capacity of the fluid, the initial and final temperatures, and the heat transfer required. It is important to calculate the mass of working fluid needed for each individual cycle to ensure efficient operation.

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