Cryogenic heat exchanger

Abstract

Nitrogen, being an inert gas is used for purging cargo ship's compartments or closed vessels. For this operation, nitrogen in a liquid state at a temperature around -180 °C, is carried in an appropriate storage vessel to the location of discharge. To avoid thermal shocks in the ship's plates, nitrogen is not directly discharged for purging from the vessel to the ship's hull, but it is passed through a heat exchanger to enhance the transfer of heat to a secondary fluid, rising sufficiently the nitrogen's exit temperature to a safe working measure. Heat exchangers may exist in a wide variety of types, shapes, sizes and arrangements. Their design is a complicated matter, it involves a consideration of heat transfer and pressure drop analysis, sizing and performance estimations, and economic aspects. The purpose of this project is to design and build a model of a recuperative type heat exchanger for expanding liquid nitrogen according to the required specifications and to investigate: i) effects of ice formation around a horizontal cylinder; ii) the transient response of the heat exchanger.