Recognizing potential of LiDAR for comprehensive measurement of sea spray flux for improving the prediction of marine icing in cold conditions - A review

Marine icing phenomenon depends on multiple variables like vessel characteristics and uncertain factors like environmental parameters, developing an accurate model for its forecasting, evaluation, and estimation is very challenging. Commonly, most severe ice accretion is caused due to sea spray. The past attempts to measure impinging sea spray flux were carried out on specific parts of the spray cloud, and most of the empirical spray-flux expressions presented only work in specific conditions. This necessitates further real-time and accurate field measurements of the entire impinging spray flux carried out in multiple scenarios in order to develop more practical correlation. High temporal and spatial resolution measurements and scanning ability of the LiDAR technique has proven to be useful in the agricultural domain for studying pesticide spray drift. This work reviews the past studies carried out using LiDAR technique for measuring the evolution of the pesticide spray cloud, asserting the potential of using a shipborne LiDAR for analysing sea spray in the study of marine icing phenomenon. The LiDAR system is capable to visualise the evolution of the sea spray drift with a high spatial and temporal resolution, which can enable comprehensive real-time measurement of spray flux for the entire sea spray cloud

Surveying drifting icebergs and ice islands: Deterioration detection and mass estimation with aerial photogrammetry and laser scanning

Icebergs and ice islands (large, tabular icebergs) are challenging targets to survey due to their size, mobility, remote locations, and potentially difficult environmental conditions. Here, we assess the precision and utility of aerial photography surveying with structure-from-motion multi-view stereo photogrammetry processing (SfM) and vessel-based terrestrial laser scanning (TLS) for iceberg deterioration detection and mass estimation. For both techniques, we determine the minimum amount of change required to reliably resolve iceberg deterioration, the deterioration detection threshold (DDT), using triplicate surveys of two iceberg survey targets. We also calculate their relative uncertainties for iceberg mass estimation. The quality of deployed Global Positioning System (GPS) units that were used for drift correction and scale assignment was a major determinant of point cloud precision. When dual-frequency GPS receivers were deployed, DDT values of 2.5 and 0.40 m were calculated for the TLS and SfM point clouds, respectively. In contrast, values of 6.6 and 3.4 m were calculated when tracking beacons with lower-quality GPS were used. The SfM dataset was also more precise when used for iceberg mass estimation, and we recommend further development of this technique for iceberg-related end-uses

Two-phase flow in the freeboard of a fluidised bed

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MarSpray LiDAR (MSL) for the comprehensive measurement of Sea Spray for Improving the Prediction of Marine Icing in Cold Conditions

Marine icing is a very complicated phenomenon, and its prediction, evaluation, and estimation involve many uncertainties. Commonly, the most severe ice accretion is caused by sea spray. A substantial amount of study is present on sea spray ice accretion about modelling and numerical simulations with certain assumptions and not based on comprehensive real-time data. The past techniques used to measure sea spray couldn’t provide information such as its complete droplets distribution, velocity, and concentration. The high temporal and spatial resolution measurement ability of the LiDAR technique has proven to be useful for studying pesticide spray drift in the agricultural domain. Due to its similar properties to sea spray, we proposed to use this remote measurement technique well-established in other disciplines in a new field: the study of sea spray icing. To recognize this potential, a novel LiDAR prototype named MarSpray LiDAR (MSL) is designed, built, and tested. MSL is a mono-static multi-axial LiDAR equipment specifically designed for short-range spray analysis and measurement. With certain future modifications, this equipment can be made suitable for shipborne use to retrieve marine spray properties that the past studies failed. These measurements can be applied for developing a more precise model for improving marine icing prediction in cold conditions

Particle Entrainment Studies From Dry and Wet Bed

During the Fluid Coking Process™ bitumen is sprayed into a fluidized bed of hot coke particles. The bitumen undergoes thermal cracking and is converted into gasses, condensable vapors, and solid coke, which deposits on the coke particles. These vapors rise through the vessel and result in entrainment of coke particles. Wet fine coke particles from the freeboard region enter the cyclone and contribute to the fouling of the Coker cyclones which can lead to the premature shut-down of Fluid Cokers. The primary objective of this research is to determine how bed wetness affects entrainment. First, a new fluidized bed was constructed, and a novel pseudo-isokinetic sampling was developed and tested to collect entrained solids. Then the entrainment from the dry bed in the bubbling and the turbulent regime was investigated. The cluster analysis was performed and showed an improvement in predicting the flux of solids ejected from bed surface, above the TDH, and across the freeboard. In the next chapter, the effect of the different levels of bed wetness on flux and size distribution of the entrained particles was studied, and the results were compared to the ones obtained for the dry bed. It was observed that in the bubbling regime, the presence of liquid can change the bubble properties in the bed which will affect the entrainment. However, the effect of low liquid loading on entrainment in turbulent regime was found to be negligible. In the final chapter, RPT was employed and it was found that the motion of ejected clusters in the freeboard could not be tracked as the clusters move too fast for the strength of radioactive that was used. Moreover, a new model to measure the entrainment of clusters in the freeboard using a modified radioactive tracer technique in which the detectors are collimated was proposed. It was found that this method only provides the decay coefficient of the clusters flux decay

A long-term record of sea ice thickness in the Canadian Arctic

Sea ice plays a vital role in the Arctic region and affects numerous processes: it influences the radiative budget by reflecting sunlight and acts as a barrier for heat transport between atmosphere and ocean; it influences Arctic ecosystems as a habitat for different species; it is important for hunting and travel for local communities; and it acts as a hazard for marine shipping. Monitoring sea ice, specifically its thickness, is essential in understanding how it is changing with ongoing global warming.This thesis presents a novel method to create a long-term record (1996-2020) for sea ice thickness in the Canadian Arctic and assesses how sea ice thickness changed and what the impacts of these changes are.This thesis initially aimed to extract a long-term sea ice thickness record for the Canadian Arctic from satellite altimetry. However, it revealed that assumptions regarding the snowpack, sea ice density, and processing algorithms highly influence conclusions on sea ice thickness state and trends, and this approach was rejected. Instead, this thesis presents a proxy sea ice thickness product for the Canadian Arctic using ice charts, which for the first time consistently covers the Canadian Arctic Archipelago. In the final research chapter, this sea ice thickness proxy product and ice charts are used to assess sea ice changes in the Canadian Arctic Archipelago and their impact on accessibility.Sea ice has thinned across most of the Canadian Arctic region, with a mean change over the full area of 38.5 cm for November and 20.5 cm for April over the period 1996-2020. Moreover, the marine navigability is shown to increase in the access channels to the Canadian Arctic Archipelago, which enhances the possibilities for resupply for local communities. However, with continuing dynamic influx of old and thick sea ice, there is no change in full navigability of the Northwest Passage connecting the Atlantic and Pacific Oceans

Particle tracking in a lab-scale conical fluidized bed dryer

Conical fluidized bed dryers are widely used in the pharmaceutical industry due to their high heat and mass transfer characteristics. Despite their widespread use, very little is known about the hydrodynamics of conical fluidized bed dryers. Wet pharmaceutical granule has high moisture content and wide particle size distribution (PSD), which can lead to poor mixing and non uniform drying. Uneven moisture content in the final product can adversely affect the quality and shelf life of these high value drugs. Previous studies on the conical fluidized bed dryers focused on the study of the gas phase, however motion of particulate phase has never been studied. Particle tracking is an important tool to study the motion of the particulate phase. Two particle tracking techniques were developed and used to study the motion of the particulate phase in a conical fluidized bed dryer. The first technique was radioactive particle tracking (RPT) which was developed at the University of Saskatchewan laboratory for a vessel having conical geometry. Experiments were conducted using dry pharmaceutical granule and during the actual drying of wet pharmaceutical granule. Two radioactive tracers of different sizes (1.6 to 2.6 mm) were tracked in each set of experiments to determine the effect of particle size on particle motion and particle mixing. Superficial gas velocities of 1, 1.5, 2 and 2.5m/s were used in dry bed studies to quantify the effect of superficial gas velocity. The second particle tracking technique was developed at the labs of Merck Frosst Canada Inc. Movies were captured using a high speed video camera coupled to a borescope and then analyzed off-line using image analysis software.Three powders having mean particle diameters of 774, 468 and 200 microns were used. Experiments were conducted at superficial gas velocities of 1.5, 2 and 3 m/s. RPT revealed that there is a distinct circulation pattern of the particulate phase. Particles move upwards at high velocities near the centre of the bed and fall slowly near the walls. Furthermore, most of the gas flow is concentrated near the centre of the bed and the circulation pattern was observed at all the superficial gas velocities. Particle size of the tracer particle and PSD of the bed material had an appreciable impact on particle mixing with bigger particles exhibiting higher segregation tendencies than the smaller ones in the case of dry granule having a broad PSD. Particle segregation due to size difference was more pronounced at a superficial gas velocity of 1 m/s. However, segregation decreased with an increase in superficial gas velocity. During drying of wet granule, particle mixing and motion of the tracer particle was poor during the first 7 minutes of drying suggesting that most of the gas flow was concentrated near the centre of the bed. Particle mixing and average particle speeds increased considerably when the moisture content in the granule was less than 18 wt% suggesting a change in the hydrodynamics of the bed with the gas being more evenly distributed throughout the bed. Image analysis of high speed movies also suggested that a dilute region existed at the center of the bed. These observations were in agreement with the observations made by RPT