The wind power industry is one of the fastest-growing renewable energy industries in the world. Since more energy can be extracted from wind when the density is higher, a lot of the investments made in the wind power industry are made in cold climates. But with cold climates come harsh weather conditions such as icing. The icing on wind power rotor blades causes the aerodynamic properties of the blade to shift and with further ice accretion, the wind power plant can come to a standstill causing a loss of power, until the ice is melted. How big these losses are, depend greatly on site-specific variables such as elevation, temperature, and precipitation. The literature claims these ice-related losses can correspond to 10-35% of the annual expected energy output. Some studies have been made to standardize an ice loss determining method to be used by the industry, yet a standardization of calculating these losses do not exist. It was therefore interesting for this thesis to investigate the different methods that are being used. By using historical Supervisory Control and Data Acquisition (SCADA) data for two different sites located in Sweden, a robust ice determining code was created to identify ice losses. Nearly 32 million data points are being analyzed, and the data itself is provided by Siemens Gamesa which is one of the biggest companies within the wind power industry. A sensitivity analysis was made, and it was shown that a reference dataset reaching from May to September for four years could be used to clearly identify ice losses. To find the ice losses, three different scenarios were tested. The three scenarios use different temperature intervals to find ice losses. For scenario 1 all data points below 0 degrees are investigated. And for scenario 2 and 3 this interval is stretching from 3 degrees and below versus 5 degrees and below. It was found that Scenario 3, was the optimal way to identify the ice losses. Scenario 3 filtered the raw data so that only data points with a temperature below five degrees was used. For the two sites investigated, the annual ice losses were found to lower the annual energy output by 5-10%. Further, the correlation between temperature, precipitation, and ice losses was investigated. It was found that low temperature and high precipitation is strongly correlated to ice losses.

Manganese (Mn) is an important element in soil, it occur natural in minerals and precipitated as Mn-oxides. Several factors could decide the solubility and mobility of Mn in soil water. In this study, the impact of road de-icing salts (NaCl) on manganese mobilization and transport to groundwater in roadside soils has been investigated by leaching tests. Generally, in the salt solution leachates, the water-soluble concentrations of Mn tended to increase with elevated salt concentrations, suggesting that ion exchange mainly affected the mobilization. The process was also attributed to the complexion with Cl. Associated with exchangeable concentration of Mn and soil properties such as pH and acidity, the mobilizations of Mn varied. Mn-oxides can dissolve when reduced condition exists, therefore the oxalate extractable Mn was extracted to estimate the change of redox potential condition in roadside soils. The redox potential of soil samples is higher in general. Redox condition has little effect on the Mn solubility and mobility in this research. Although groundwater samples indicated that only a few periods and sites were under threaten of elevated concentrations of manganese, there is still great risk of transport of high water-soluble concentrations of Mn in roadside soils to groundwater, especially the areas exposed to de-icing salts. In addition, lower value of Mn concentrations in groundwater for considering good drinking water quality for the well-being of children should be paid more attention to.

Winter road maintenance activities are crucial for maintaining the accessibility and traffic safety of the road network during winters. Common winter road maintenance activities include plowing and the use of de-icing agents (e.g. NaCl) to avoid freezing. Effective winter road maintenance strives towards keeping the roads free from snow and ice while reducing negative side effects of winter road maintenance, such as ground water contamination from road salt. Since the weather is decisive for when there is an increased risk of slipperiness, the understanding and continuous observation and forecasts of the road weather are of highest importance. Sensors are commonly installed along roads to measure road weather conditions to support the road maintenance personnel in taking appropriate actions. Different types of errors and uncertainties related to sensors used for frost warnings along roads have been investigated by using a regional scale dataset from south-western Sweden. The results from this study indicate that various types of uncertainties originate from both measurements and models which have a significant impact on the winter road maintenance efficiency. To provide better information about the road surface conditions, a new method for detecting ice formation on roads is presented. Infrared sensors were used to detect temperature patterns which may occur when ice formation take place on a road surface. The investigations demonstrate the potential to improve winter road maintenance by introducing new methods to better describe the road surface conditions. / QC 20101206

This thesis investigates if the profitability of a wind farm can be increased by reducing itscontracted grid capacity. Two years of SCADA data is cleaned from non- and partialperformance which is used to estimate a wake reduced annual power time series. Stochasticmodels of production losses are applied to translate the wake reduced annual power timeseries. Ice losses are modelled with a 3-state Markov chain. The statistical properties arecalculated by identifying ice events in the SCADA. With the IEA task19 IceLoss algorithm areice events identified in the SCADA signal. An ice loss factor of 86 % is estimated for Juktanduring 2019. The results indicate that profitability can be increased by reducing the (contracted)grid capacity. Furthermore, the optimized grid capacity is shown to have low sensitivity to powerprice and ice losses. This finding is valuable since the power price market and weather areinherently difficult to predict. It follows that the prediction uncertainties of these inputs are lesssignificant when calculating the optimized grid capacity.

In a previous project, mobile exposures in road environments have been performed in various areas of the world. A number of materials and coatings have been attached under trailers which travels long distances in different types of road environments. One of the materials, zinc, demonstrated various corrosion rates in different parts of the world. In this investigation two various accelerated corrosion tests have been performed at the laboratory of Swerea Kimab in order to realize parameter influence on zinc. Even though the corrosion rates are known, the relation to formed corrosion products has not been investigated earlier. In the present study, corrosion products on zinc have been analyzed using XRD and FTIR. The results from analyses of formed corrosion products have been evaluated together with measured corrosion rates, both from the mobile exposure and the accelerated tests, in order to try to understand under what conditions certain corrosion products are formed and how it affects the corrosion rate. A cold humid climate was found to be the most corrosive. In these environments, de ‐icing salts are used which promotes formation of Simonkolleite and in a subsequent step; Gordaite (if there is a not negligible deposition rate of SO2/SO42‐) which is often observed as the end product in marine environments.

No description available.

Non-wetting surfaces offer enhanced capabilities over bare metal substrates for condensation with or without phase change. This trait can be utilized to broaden strategies in combating water scarcity in water stressed areas. Slippery lubricant infused surfaces have the ability to shed water droplets with lower nucleation times, taking advantage of more of the limited amount of time available to collect dew and fog than traditional surfaces. However, existing studies focus on short durations with scant information available on the longer-term performance or durability of the materials in application environments. To address this knowledge gap, dew harvesting studies were conducted over a 96 hour period on a lubricant infused surface vis-à-vis regular surface of the same material. Three phases of performance are identified and discussed with regard to the water harvesting potential. The second part of the thesis addresses water condensation under conditions where freezing is a potential issue. Non-wetting surfaces have been shown to be a promising method of limiting the formation of ice from sessile droplets. This study explores the effect of surface roughness on the freeze time of sessile water droplets. Superhydrophobic and hydrophobic, lubricant infused, copper surfaces were created via electrodeposition and chemical etching in conjunction with chemical treatments to achieve non-wetting surfaces of varying surface textures. Freezing characteristics on the surfaces are studied experimentally and, for the first time, computationally, wherein the surface is described using a fractal surface topography. The effect of surface engineering on the freezing dynamics and comparison between the experimental and the computational studies are elucidated. / Master of Science / The use of durable, water repelling surfaces that are also thermally conductive provide an opportunity to help alleviate strain from a growing world crisis, water scarcity. Lubricant infused surfaces shed water from their surface by providing a slippery layer for the droplets to slide on, as opposed to bare metal which water tends to cling to. This behavior makes lubricant infused surfaces attractive as a water harvesting method. However, these surfaces degrade over time and must be maintained to perform at their maximum capability, collecting water for 40 minutes more than a bare surface. This thesis focuses on the performance of these surfaces over a 96-hour operating period to characterize the effect lubricant drainage has on the water collection behavior. Freezing water droplets, commonly referred to as icing, poses concerns for safety and operational ability in industries like renewable energy generation, where icing limits efficiency. Non-wetting surfaces have a unique ability to inherently slow down the phase change of a water droplet to ice due to the lower contact area of droplets resting on the surface. This thesis examines superhydrophobic and lubricant infused surfaces of varying degrees of roughness to explore the effect that the contact angle and different surface structures have on the freezing rate of water on the surface. The experimental results are compared to numerical simulations, which is useful in designing systems that would implement this passive icing mitigation technique.

No description available.

No description available.

No description available.