Performance of the cold transport system utilizing evaporation-freezing phenomena with a cold trap

This paper dealt with the performance of a novel cold transport system for the waste cold from the gasification process of Liquefied Natural Gas (LNG), which has been proposed by one of the authors. The system consists of an evaporator, a cold trap, and a pipeline between them, and the LNG cold poured into the cold trap is transported to the evaporator as a flow of low-pressure water vapor. In this study, cold transport rate of a small-scale system was experimentally examined under various conditions, and the efficiency of cold transport was discussed. The results clearly showed that, as suggested by a theoretical relation based on the pressure drop due to vapor flow in the pipeline, cold transport rate is affected both by the pressure difference between the evaporator and cold trap, and by the length, diameter and friction factor of the pipeline. However it was also shown that the transport rate is hardly influenced by the temperature of pipeline wall. Based on the theoretical relation and the experimental results obtained herein, a guideline for designing the cold transport system was derived.