10 research outputs found
Droplet trajectory and thermal analysis of impinging saline spray flow on marine platforms in cold seas and ocean regions
No full textIn this paper, a theoretical predictive model is developed to investigate the heat and mass transfer from saline water droplets in cold seas and ocean regions. Also, the trajectory and cooling process of saline water droplets during flight over marine platforms are analyzed. The predictive model considers convection, evaporation, and radiation heat transfer from the droplet's surface to the ambient air. The results show that droplets with medium sizes can reach their maximum heights and horizontal positions at the moment of impact on the deck during flight over marine platforms. For small water droplets of approximately up to 1.1 mm, a uniform temperature within the droplet is found to be a reasonable approximation. The temperature gradient inside the droplet is small for larger droplets, because the Biot number is less than 0.5. The results indicate good agreement between the predicted results and previously published data. A sensitivity analysis is performed to examine the effects of various parameters on the trajectory and cooling process of the droplets as well as a droplet's Biot number. This analysis shows that the parameters of air temperature, droplet size, initial droplet temperature, and droplet flight time have a significant impact on the droplet cooling process, although the size of marine platforms is an important factor. Also, wind velocity plays a considerable role on the trajectory of the droplets. This model is a useful and relatively simple design tool for the analysis of thermal behaviour and prediction of the cooling process of saline water droplets.Statoil (Norway)Research and Development Corporation of Newfoundland and Labrador (RDC)MitacsPetroleum Research of Newfoundland & Labrador (PRNL)American Bureau of Shipping (ABS
Sea spray icing phenomena on marine vessels and offshore structures: Review and formulation
No full textCold ocean regions have many environmental challenges that pose risks to the stability of both marine vessels and structures and to human safety. One major hazard is the marine or sea spray icing phenomenon. Wave-impact sea spray and wind spray are the main sources of incoming water onto marine vessels and offshore structures that can cause hazardous ice accumulation on those structures. Prediction, assessment, and computation of the icing growth rate and the amount of ice accumulation are important but complex. This paper reviews the history and development of predictive models of sea spray icing on marine vessels and offshore structures. Several topics are reviewed in this paper, such as droplet trajectories, flux of seawater spray, liquid water content (LWC), heat balance at the phase interface, and icing models.Statoil ASA (Norway)MITACSResearch and Development Corporation of Newfoundland and Labrador (RDC)Petroleum Research of Newfoundland & Labrador (PRNL)American Bureau of Shipping (ABS) Grou
Marine icing phenomena on vessels and offshore structures: Prediction and analysis
No full textPast progress in prediction and modeling of ice accumulation on marine vessels and structures located in cold seas and ocean regions is reported and examined in this paper. Research studies have developed models for the estimation of sea spray icing, which is the main reason of marine platforms icing. The phenomenon of sea spray icing is one of the major hazards in cold regions. Hence, prediction, assessment and computation of the icing growth rate and the amount of ice accumulation are important but also challenging. The paper briefly reviews sea spray icing models, along with various experimental, theoretical and numerical approaches. An overall survey shows that outstanding past results were based on field observations and followed by empirical tests. Then, theoretical investigations formulated the experimental results. Also, numerical simulations have led to many predictions of icing phenomena as the supplementary research. In this paper, the sea spray icing models are classified based on when the research was conducted. To obtain more accurate and realistic results from marine icing models, evaluations of the various models have been discussed.Statoil ASA (Norway)MITACSResearch and Development Corporation of Newfoundland and Labrador (RDC)Petroleum Research of Newfoundland&Labrador (PRNL)American Bureau of Shipping (ABS
Experimental investigation of vertical marine surface icing in periodic spray and cold conditions
No full textIn this paper, the ice load accumulated on a vertical plate of marine platforms during periodic spray icing in a cold room was investigated experimentally. The mass and thickness of ice formation on the plate along with several parameters such as relative humidity, the front and back surface temperatures of the vertical plate, initial temperature of water, and the spray mass flux impinging on the plate were measured and discussed. Analysis of variance (ANOVA), which is a statistical data analysis method, was utilized to interpret the contribution of the investigated parameters during the icing experiments, comparing the effect of each parameter and their interactions on the quantity of ice accumulated on the vertical plate. The primary analysis of the empirical results illustrates that the ambient temperature, airflow velocity, the distance between the fan and the plate, salinity and the timing of spray events have influences in the icing intensity and the amount of ice formation on the vertical plate. The errors between the average ice thicknesses obtained from two different experimental approaches were from 5 to 20%. For the saline ice formation, the temperature difference between the front and back of the vertical plate was greater than that of the pure ice formed during the spray icing event. The primary experimental results alongside the ANOVA analysis verified that airflow velocity is the most effective parameter, with a high level of interaction for time and temperature
Heat transfer of impinging seawater spray and ice accumulation
No full textIn this paper, a new predictive model for the ice layer and water film growth, which occurs due to seawater spray impinging on large horizontal surfaces of a supply vessel, is developed using a Stefan-type problem formulation. The icing model includes conduction heat transfer in the ice and brine film layer, assuming the volume and distribution of brine pockets and air bubbles within the ice accumulation are uniform. The model also uses heat and mass balances to predict the freezing fraction, temperature distribution, ice layer and water film thickness. The results show that the water film salinity and icing intensity change with time during the icing period. Additionally, the water film salinity variations affect the freezing temperature, thermal conductivity and specific heat capacity of ice formation. As a result, heat conduction within the accumulated ice changes with time due to the variations of salinity; thus, the conduction heat flux has a significant effect on the ice thickness growth rate. This new model is a useful tool for forecasting and assessing the potential ice accumulation on marine vessels and structures
Heat transfer of impinging seawater spray and ice accumulation on marine vessel surfaces
No full textIn this paper, a new predictive model for the ice layer and water film growth, which occurs due to seawater spray impinging on large horizontal surfaces of a supply vessel, is developed using a Stefan-type problem formulation. The icing model includes conduction heat transfer in the ice and brine film layer, assuming the volume and distribution of brine pockets and air bubbles within the ice accumulation are uniform. The model also uses heat and mass balances to predict the freezing fraction, temperature distribution, ice layer, and water film thickness. The results show that the water film salinity and icing intensity change with time during the icing period. Additionally, the water film salinity variations affect the freezing temperature, thermal conductivity, and specific heat capacity of ice formation. As a result, heat conduction within the accumulated ice changes with time due to the variations of salinity; thus, the conduction heat flux has a significant effect on the ice thickness growth rate. This new model is a useful tool for forecasting and assessing the potential ice accumulation on marine vessels and structures
Multistage cooling and freezing of a saline spherical water droplet
No full textIn this paper, the thermal behaviour of a saline water droplet during flight over a marine vessel in cold weather conditions is investigated by analytical and semi-analytical techniques. To predict and analyze the droplet cooling and freezing processes, three stages are employed: a liquid cooling stage, a solidification stage, and a solid cooling stage. The theoretical model considers heat transfer via conduction inside the droplet as well as convection, evaporation (just for the liquid cooling stage), and radiation heat transfer from the droplet's surface to the ambient air. A novel semi-analytical solution technique is developed to analyze the inward moving boundary problem for the solidification stage. The results show that the liquid cooling stage is very short, and the temperature at the droplet's center remains close to the initial droplet temperature. During the solidification stage, the velocity of the inward freezing front within the droplet is approximately constant, and the temperature variations are linear when the temperature inside the droplet reaches the freezing temperature. The solid cooling stage is much longer than the other stages, and the temperature changes are non-linear. For a case study, theoretical predictions show that the average temperature of a droplet with a diameter of 1 mm at the moment of impact on the deck is approximately −1.95°C. Moreover, there is an ice shell with a thickness of 0.06 mm on the surface of the water droplet at the moment of impact.Statoil (Norway)Research and Development Corporation of Newfoundland and Labrador (RDC)MITACSPetroleum Research of Newfoundland & Labrador (PRNL)American Bureau of Shipping (ABS)NSERC Discovery Grant progra
Analysis of ice accretion on vertical surfaces of marine vessels and structures in arctic conditions
No full textThe phenomenon of icing in cold climates is a challenging problem of engineering analysis, which involves heat transfer, phase change and multiphase flow with water droplets. This phenomenon has an important impact on the performance and operation of marine vessels, offshore structures, and others such as wind turbines, power lines, and aircraft surfaces. In this paper, a predictive icing model for large vertical surfaces of a marine vessel is developed theoretically. The total flux of sea-spray, including wave spray and wind spray, is analyzed during the spray process. By using heat, mass and salt concentration balances, the freezing fraction, temperature distribution, ice layer thickness, and liquid film thickness are determined. The results are compared with the numerical and experimental results of other studies. Good agreement between the theoretical predictions and other results demonstrates the improved accuracy of the proposed method over past models
Resonant Light Scattering Toward Optical Fiber Humidity Sensors
No full textAbstract The deposition of tetrakis (4-sulonatophenyl) porphyrin (TPPS) thin film on optical fibers presents many possibilities for sensing applications. The J-form aggregation with a narrow and sharp spectral feature at about 490 nm and its sensitivity to humidity have been discussed; a fast change of wavelength occurs according with variation in the humidity level. The reproducibility and high sensitivity of TPPS-coated fibers, along with the capabilities of optical fibers, suggest the device as a good candidate for humidity sensing in harsh environments
Thermal analysis of saline droplet motion with cooling in cold regions
No full textIn this paper, a theoretical approach is employed to analyze the thermal behaviour and study the cooling process of water droplets in cold regions. Additionally, the effect of several parameters, such as air temperature, droplet size, initial droplet temperature, relative humidity and droplet salinity on the cooling process is investigated. The model contains convection, evaporation, and radiation heat transfer from the droplet’s surface and a uniform temperature across the droplet. The results illustrate a good agreement between the theoretical predictions and previously measured data. Furthermore, droplet size, air temperature, initial droplet temperature, and droplet flight time have a substantial effect on the droplet cooling process. This model is a useful tool to investigate the thermal behaviour and the cooling process of water droplets
