RACA Journal November 2025 RACA_November2025 | Page 40

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Fill factor: The fill factor and the ambient temperature are the deciding factors determining the pressure in the system. This method may be applied only for the receiver or for a simple one stage system. The fill factor is the quotient of the charge mass and complete volume of the system. A system with a volume of 2dm ³ and a charge of 560g carbon dioxide has a fill factor of 280kg / m3. If the ambient temperature is 40 ° C, the expected maximum pressure is 8 000kPa( 80 bars). If the filling factor is only 200kg / m-3, the expected maximum pressure is 7 000kPa.

Heat recovery: And finally, we can increase the efficiency of the system utilising heat recovery. Heat recovery is one of most efficient ways to increase the total efficiency of the refrigeration system. Heat recovery systems are used for tap-water heating,

space heating or heating a HVAC system. The systems work on the same principles as a system for conventional( HFC) refrigeration systems, HCs and Ammonia( R717).

Cayla, thank you for your question. I hope that this helps with your understanding the use of R744 in refrigeration systems. RACA

Schematic for a heat revery solution.

“ During the design stage, the total volume, or piping and components, refrigerant charge and maximum pressure for expected ambient temperatures is determined.”

RACA Journal I November 2025 www. refrigerationandaircon. co. za