Liquid nitrogen cocktail in the preparation of frozen desserts, such as ice cream, which can be created within moments at the table because of the speed at which it cools food. Similarly, liquid nitrogen has become popular in the preparation of cocktails because it can be used to quickly chill glasses or freeze ingredients. It is also added to drinks to create a smoky effect, which is created by the cold nitrogen vapour (liquid nitrogen boils at -195.8 Celsius at normal atmospheric pressure) condensing the moisture (i.e., water vapor) in the surrounding air above. Because of its low temperature liquid nitrogen can be
Gas–liquid contactor is higher for equipment with higher values of gas–liquid interface surface area, so gas–liquid contactors with high surface area (e.g. packed column, spray tower) are often preferred when it is important to lower the cost of the equipment. Liquid hold-up is also an important factor for the economy of the process, because for low values of liquid hold-up a bigger equipment is needed to have the same heat and mass transfer velocity. For this reason, gas–liquid contactors with low liquid-hold-up (e.g. falling-film column) in general are not used at industrial scale. Gas–liquid contactor A gas–liquid contactor is a particular chemical