Investigation of the effects of CO2 pre-cooling on the cooling capacity for cryogenic cooling in machining operations

Abstract

Liquid carbon dioxide (LCO₂) based cryogenic cooling has shown promising results in terms of wear reduction, productivity increase and energy efficiency when machining high-temperature materials. For process-safe use with low pulsation, CO₂ must be fed in the liquid state to cool the process zone. LCO₂ is typically stored in riser bottles in which gaseous and liquid aggregate state coexist. A preliminary study has already shown that the liquefied state of the CO₂ can be stabilized by pre-cooling. In this paper, the influence of a heat exchanger as a pre-cooling system on the cooling capacity of the CO₂ is investigated and the required energy consumption is compared to unstabilized CO₂, pressure increased CO₂ and compressed air. It has been shown that pre-cooling leads to a more energy-efficient increase in the cooling capacity of the CO₂ compared to pressure increased CO₂.