The boiling suppression of liquid nitrogen

TL;DR

This study quantitatively investigates how injecting helium gas into boiling liquid nitrogen suppresses boiling by cooling the liquid through internal evaporation into helium bubbles, resulting in a flat liquid surface.

Contribution

It provides the first comprehensive quantitative analysis of boiling suppression in liquid nitrogen caused by helium gas injection, focusing on internal evaporation effects.

Findings

Boiling is suppressed by helium injection, creating a mirror-like surface.

Cooling occurs via internal evaporation of nitrogen into helium bubbles.

Internal evaporation is identified as the key mechanism for boiling suppression.

Abstract

When He gas is injected from room temperature into boiling liquid N$_{2}$, boiling is suppressed, leaving liquid surface flat like a mirror. Although the qualitative explanation for this phenomenon is known [Minkoff G J \textit{et al}. Nature 1957;180(4599):1413-4.], it has not been studied quantitatively and comprehensively yet. In this report, we made careful simultaneous measurements of temperature and weight variation of the liquid. The results clearly indicate that the boiling suppression is caused by cooling of the liquid with "internal evaporation" of N$_{2}$ into the He bubbles.