Equipment and Production of Columnar Sea Ice Replica in NTNU Cold Lab

Abstract

This Master's thesis considers an ice tank used for production of ice in a cold lab at NTNU. The goal was to improve the temperature control of the water in the tank. Original sensors were replaced with seven new sensors with a resolution of 0.1 degrees C. The temperature was controlled by a computer program made in LabVIEW. A P-controller was used to control and stabilize water temperature.The system was modified and tested with three different experiments. One with production of freshwater ice and two with sea ice. The tests examined the temperature development in the tank and resulting ice sheet thickness.The temperature measurements showed stability, but with small local variations of 0.1 degrees C which were consistent throughout every test. This was either caused by convective mixing or an insufficient calibration of sensors. Ice temperatures could also be measured after the modifications were done.The ice was found to be thicker along the tank wall as expected, but less severely compared to observations made before the modifications. A comparison between the walls found a difference in thickness, and was probably caused by the location of the tank relative to the lab room's cooling system.This Master's thesis also investigates how the time spent on spraying, for initiation of crystal growth, affects the crystal size when producing sea ice. Two tests were conducted; short and long spraying time. The results showed that the spraying time had a significant impact on the resulting ice structure. The grain size of the crystals from the short spraying test was approximately 1/3 of the grain size from the long spraying test