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William David Lubitz
School of Engineering University of Guelph Guelph Canada

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Review paper
Published: 14 June 2021 in International Journal of Energy Research
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Archimedes screws have been used as pumps since antiquity and have more recently been implemented in micro-hydropower plants as an ecologically advantageous technology. They are regarded as a hydropower technology with lower environmental impact since they allow safe passage of aquatic flora and fauna through slow turning, widely spaced blades during operation. Archimedes screw generators (ASGs) operate at river-to-wire efficiencies at approximately 75% with relatively low installation and maintenance costs when compared to other hydropower technologies of the same scale. ASGs are relatively simple and cost-efficient to manufacture—simple enough to create in the seventh century BCE. Modern manufacturing techniques for sheet metal and fabrication have refined ASG production. The literature contains various parametric models for predicting screw power output, and more recent numerical simulations have provided insight into the fluid mechanics of screw generators. The knowledge gained from these studies has allowed researchers to suggest more optimal designs for Archimedes screws. However, much can be done to further improve the accuracy of power prediction models. This paper discusses the current state of the literature for ASGs, and highlights areas for future research to improve power prediction and optimization capabilities for researchers and industrial designers. Highlights Archimedes screws are an ancient pumping technology that have more recently found use as a hydropower-producing technology. Archimedes screw generators (ASGs) are a small-scale hydropower technology that may be installed as a run-of-river installation. ASGs are an eco-friendly technology that allow for the safe passage of sediments, small debris, fish, and other aquatic wildlife through their flights during operation. There are few experiments and computational fluid dynamic simulations that have sought to extend the literature's data on ASG operation. Current performance models for ASGs lack robust validation to be properly implemented in power plant design.

ACS Style

Scott Christopher Simmons; William David Lubitz. Archimedes screw generators for sustainable micro‐hydropower production. International Journal of Energy Research 2021, 1 .

AMA Style

Scott Christopher Simmons, William David Lubitz. Archimedes screw generators for sustainable micro‐hydropower production. International Journal of Energy Research. 2021; ():1.

Chicago/Turabian Style

Scott Christopher Simmons; William David Lubitz. 2021. "Archimedes screw generators for sustainable micro‐hydropower production." International Journal of Energy Research , no. : 1.

Journal article
Published: 01 March 2021 in Journal of Hydraulic Engineering
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Three laboratory-scale Archimedes screw generators were tested for their power production. They were tested at different inclination angles corresponding to their lengths in order to maintain a constant head for each screw. Experimentation was used to develop initial insight into the effect of inclination angle on Archimedes screw power production. Computational fluid dynamic simulations were then compared to the experimental data and evaluated for their accuracy. The model was found to be acceptable and was then used to extend the data set to a total of seven inclination angles across the range of β=10°–40°. It was found that Archimedes screw generators with shallower inclination angles produced more power. It was also noted that shallower inclination angles correspond to longer screws and, thus, more civil infrastructure costs. The authors suggest that the ideal inclination angle for an Archimedes screw generator installation is between β=20° and 25° based on this laboratory-scale testing.

ACS Style

Scott Simmons; Guilhem Dellinger; Murray Lyons; Abdelali Terfous; Abdellah Ghenaim; William David Lubitz. Effects of Inclination Angle on Archimedes Screw Generator Power Production with Constant Head. Journal of Hydraulic Engineering 2021, 147, 04021001 .

AMA Style

Scott Simmons, Guilhem Dellinger, Murray Lyons, Abdelali Terfous, Abdellah Ghenaim, William David Lubitz. Effects of Inclination Angle on Archimedes Screw Generator Power Production with Constant Head. Journal of Hydraulic Engineering. 2021; 147 (3):04021001.

Chicago/Turabian Style

Scott Simmons; Guilhem Dellinger; Murray Lyons; Abdelali Terfous; Abdellah Ghenaim; William David Lubitz. 2021. "Effects of Inclination Angle on Archimedes Screw Generator Power Production with Constant Head." Journal of Hydraulic Engineering 147, no. 3: 04021001.

Conference paper
Published: 05 January 2021 in Springer Proceedings in Energy
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Predicting the power output of Archimedes screws is computationally intensive. It takes a minimum of eight variables to geometrically define a screw and its operating conditions, and more are needed for more detailed performance modeling. The set of variables that describe the screw are all interrelated: the optimum value of one variable depends on the values of the others, and it is not possible to determine an optimum value of any individual variable in isolation from the others. Dimensional analysis was identified as a way to improve understanding of the effect of different variables on Archimedes screw performance, and a set of dimensionless variables were defined to describe Archimedes screws. Archimedes screws are geometrically similar for all useful screw sizes, from small laboratory prototypes to large grid-connected plants. This means that relationships between the non-dimensional variables from this study can be applied to screws of any scale and used to predict the performance of the screw. Relationships between the non-dimensional variables are explored using a previously developed comprehensive Archimedes screw performance model, leading to new insights into the relationship between screw geometric variables and power output. One result is that a two-dimensional solution space is proposed for the examination of the performance of a screw generator. An optimal relationship between flow rate and rotation speed which maximizes power production at each flow rate is determined for a given screw geometry.

ACS Style

Murray Lyons; William David Lubitz. Non-dimensional Characterization of Power-Generating Archimedes Screws. Springer Proceedings in Energy 2021, 39 -51.

AMA Style

Murray Lyons, William David Lubitz. Non-dimensional Characterization of Power-Generating Archimedes Screws. Springer Proceedings in Energy. 2021; ():39-51.

Chicago/Turabian Style

Murray Lyons; William David Lubitz. 2021. "Non-dimensional Characterization of Power-Generating Archimedes Screws." Springer Proceedings in Energy , no. : 39-51.

Conference paper
Published: 05 January 2021 in Springer Proceedings in Energy
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Archimedes Screw Turbines (ASTs) are a new form of hydraulic energy converter for small hydroelectric powerplants. ASTs can operate even with very low levels of water and are a safer solution for wildlife and especially fish. It is very important to have an estimation about the volume of water that can pass through the screw for designing AST hydropower plants, making operation plans and operation. However, developing a general relationship for the volume of flow entering an AST as a function of inlet water level and other variables for all screw sizes is challenging: In ASTs, water flows through a helical array of blades that are wrapped around a central cylinder while there is a small gap between the trough and screw which could be considered as free flow. Screw geometry and rotation speed are two other important factors that intensify the scaling difficulties. In this study, an equation is developed to estimate the volume flow rate that passes through an AST based on its inlet water level, rotation speed and pitch. The resulting relationship is validated using data from five lab-scale and one full-scale AST. Then it is optimized using Genetic Algorithms to produce a general equation for all screw sizes. Data analysis is completed to find and control effective parameters by using principal component analysis (PCA) techniques. Finally, the equation is modified to maximize accuracy. Results indicate that the proposed equation can estimate the volume flow rates of both lab-scale and full-scale studied screws with reasonable accuracy.

ACS Style

Arash YoosefDoost; William David Lubitz. Development of an Equation for the Volume of Flow Passing Through an Archimedes Screw Turbine. Springer Proceedings in Energy 2021, 17 -37.

AMA Style

Arash YoosefDoost, William David Lubitz. Development of an Equation for the Volume of Flow Passing Through an Archimedes Screw Turbine. Springer Proceedings in Energy. 2021; ():17-37.

Chicago/Turabian Style

Arash YoosefDoost; William David Lubitz. 2021. "Development of an Equation for the Volume of Flow Passing Through an Archimedes Screw Turbine." Springer Proceedings in Energy , no. : 17-37.

Research paper
Published: 21 December 2020 in Journal of Hydraulic Research
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Two computational fluid dynamics models were developed to analyse the internal fluid mechanics of an Archimedes screw’s buckets. The models were evaluated against laboratory-scale experimental data, which suggested that they were acceptably accurate. Results of power-generating torque, internal fluid velocities, wall shear stress, and leakage flow rates were all explored with respect to changing rotational speeds. It was found that increasing rotational speed while maintaining “full” screw buckets would produce: similar torque values (by extension: power increased), higher velocity magnitudes of fluid parcels in a bucket, less gap leakage flow rate, and higher wall shear stress rates (by extension: more frictional losses).

ACS Style

Scott Christopher Simmons; William David Lubitz. Analysis of internal fluid motion in an Archimedes screw using computational fluid mechanics. Journal of Hydraulic Research 2020, 1 -15.

AMA Style

Scott Christopher Simmons, William David Lubitz. Analysis of internal fluid motion in an Archimedes screw using computational fluid mechanics. Journal of Hydraulic Research. 2020; ():1-15.

Chicago/Turabian Style

Scott Christopher Simmons; William David Lubitz. 2020. "Analysis of internal fluid motion in an Archimedes screw using computational fluid mechanics." Journal of Hydraulic Research , no. : 1-15.

Review
Published: 08 September 2020 in Sustainability
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Archimedes Screws Turbines (ASTs) are a new form of small hydroelectric powerplant that can be applied even in low head sites. ASTs offer a clean and renewable source of energy and are safer for wildlife and especially fish than other hydro generation options. As with other energy solutions, ASTs are not a global solution for all situations. However, in terms of sustainable development, ASTs can offer many economic, social, and environmental advantages that make them an important option for providing sustainable hydropower development. Archimedes screws can operate in low water heads (less than about 5 m) and a range of flow rates with practical efficiencies of 60% to 80% and can generate up to 355 kW of power. ASTs increase the number of suitable sites where it is possible to develop sustainable hydropower, including in undeveloped, hard to access regions and small communities. At many low head sites, ASTs may be more cost-effective, with lower installation and operating costs than alternative hydropower systems. An AST may also reduce the disturbance of natural sedimentation and erosion processes and have smaller impacts on fish and other fauna. ASTs can often be retrofit to existing unpowered dams or weirs, providing new hydropower capacity for very little marginal environmental impact. This review outlines the characteristics of ASTs, then discusses and analyzes how they could benefit the sustainability of hydropower development.

ACS Style

Arash YoosefDoost; William Lubitz. Archimedes Screw Turbines: A Sustainable Development Solution for Green and Renewable Energy Generation—A Review of Potential and Design Procedures. Sustainability 2020, 12, 7352 .

AMA Style

Arash YoosefDoost, William Lubitz. Archimedes Screw Turbines: A Sustainable Development Solution for Green and Renewable Energy Generation—A Review of Potential and Design Procedures. Sustainability. 2020; 12 (18):7352.

Chicago/Turabian Style

Arash YoosefDoost; William Lubitz. 2020. "Archimedes Screw Turbines: A Sustainable Development Solution for Green and Renewable Energy Generation—A Review of Potential and Design Procedures." Sustainability 12, no. 18: 7352.

Journal article
Published: 01 August 2020 in Journal of Hydraulic Engineering
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There is essentially no experimental data on Archimedes screw pump performance available in the literature that is sufficiently detailed for model validation. Experiments were conducted on a laboratory scale (0.3-m diameter) Archimedes screw pump to characterize the pumping efficiency of the screw pump at various inlet basin water levels and screw rotation speeds. The results provide new insights into the effect of inlet and outlet basin level on screw pump efficiency. The flow rate of water pumped is proportional to the rotation speed of the screw, and increases with increasing inlet basin depth until the basin level exceeds that needed to fully fill the screw without overflowing. Comparisons are made to available empirical and analytically derived guidelines regarding optimal lower basin water levels, upper basin water levels and rotation rates for an Archimedes screw pump. Some differences are noted between recommended optimal conditions for full-size screws from the literature, and the optimum conditions found for the tested laboratory-size screw. These differences are consistent with expected effects of scaling between different size screws.

ACS Style

Murray Lyons; Scott Simmons; Maxwell Fisher; James Sebastien Williams; William David Lubitz. Experimental Investigation of Archimedes Screw Pump. Journal of Hydraulic Engineering 2020, 146, 04020057 .

AMA Style

Murray Lyons, Scott Simmons, Maxwell Fisher, James Sebastien Williams, William David Lubitz. Experimental Investigation of Archimedes Screw Pump. Journal of Hydraulic Engineering. 2020; 146 (8):04020057.

Chicago/Turabian Style

Murray Lyons; Scott Simmons; Maxwell Fisher; James Sebastien Williams; William David Lubitz. 2020. "Experimental Investigation of Archimedes Screw Pump." Journal of Hydraulic Engineering 146, no. 8: 04020057.

Journal article
Published: 29 June 2019 in LWT
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Air flow characteristics and decontamination efficacy are investigated within a forced-air ozone reactor designed to control Listeria monocytogenes on apple fruit. The commercial reactor introduced an air-ozone mix through a column of apples (540 kg contained within two bins; dimensions 1.21 m × 1.21 m × 0.72 m) for a defined air velocity and time period. The apple bed had high porosity (ɛ = 0.533) with a corresponding low pressure differential (10 Pa/m). Incoming air flowed through the ozone generator with low air velocities (0.022 m/s) introducing 39 ppm of the antimicrobial gas into the chamber. As the air flow was increased to 0.147 m/s, the corresponding ozone concentration at the entry point into the chamber dropped to 4 ppm through dilution. At the lowest air velocity the log reduction of Lactobacillus (surrogate bacteria for Listeria) inoculated onto applies varied between 0.5 and 2.5 log CFU across the bed, compared to 1.6 to 2.5 log CFU reductions that were observed at air velocities greater than 0.088 m/s. It was found the homogeneity in decontamination efficacy across the bed was primarily dependent on the applied air velocity with ozone concentration (4–39 ppm) and treatment time (5–40 min) being less influential.

ACS Style

J. Arévalo Camargo; K. Murray; K. Warriner; W. Lubitz. Characterization of efficacy and flow in a commercial scale forced air ozone reactor for decontamination of apples. LWT 2019, 113, 108325 .

AMA Style

J. Arévalo Camargo, K. Murray, K. Warriner, W. Lubitz. Characterization of efficacy and flow in a commercial scale forced air ozone reactor for decontamination of apples. LWT. 2019; 113 ():108325.

Chicago/Turabian Style

J. Arévalo Camargo; K. Murray; K. Warriner; W. Lubitz. 2019. "Characterization of efficacy and flow in a commercial scale forced air ozone reactor for decontamination of apples." LWT 113, no. : 108325.

Journal article
Published: 18 January 2019 in Renewable Energy
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A computational fluid dynamic (CFD) simulation of an Archimedes screw generator (ASG) was carried out in conjunction with laboratory-scale experiments to determine the effect of inclination angle and number of blades on ASG power production and performance. Good agreement was found between the model and experiment; the CFD model had relative errors in hydraulic efficiency of less than 2% in optimal cases. Both the experiments and CFD simulations were carried out for inclination angles between 10° and 38°. Afterwards CFD was used to simulate the effect of three different numbers of blades (3, 4 and 5) of an ASG with common design parameters. Overflow and gap leakage losses were found to increase at higher inclinations - these losses decreased with the addition of blades. For this particular ASG setup, the 5-bladed screw generated the most power. The 4 and 5-bladed screws had their highest efficiencies at inclination angles between 20° and 24.5°. The 3-bladed screw was found to have its highest efficiencies at comparatively lower inclination angles, with the simulations finding the optimal angle to be approximately 15.5°. Both CFD simulations and the experiments showed that overflow leakage started to happen much sooner at higher inclination angles, as expected.

ACS Style

Guilhem Dellinger; Scott Simmons; William David Lubitz; Pierre-André Garambois; Nicolas Dellinger. Effect of slope and number of blades on Archimedes screw generator power output. Renewable Energy 2019, 136, 896 -908.

AMA Style

Guilhem Dellinger, Scott Simmons, William David Lubitz, Pierre-André Garambois, Nicolas Dellinger. Effect of slope and number of blades on Archimedes screw generator power output. Renewable Energy. 2019; 136 ():896-908.

Chicago/Turabian Style

Guilhem Dellinger; Scott Simmons; William David Lubitz; Pierre-André Garambois; Nicolas Dellinger. 2019. "Effect of slope and number of blades on Archimedes screw generator power output." Renewable Energy 136, no. : 896-908.

Conference paper
Published: 30 December 2018 in Springer Proceedings in Energy
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Simple greenhouses constructed of polyethylene glazing over a steel frame with roll-up sides, called high tunnels, are used in horticulture to extend the growing season, improve crop quality, reduce disease, and reduce pest control issues. The high tunnel is effectively a passive solar structure installed over a crop that is grown using conventional, soil-based methods. Unlike large, hydroponic greenhouses, there are no fans or automated ventilation controls, nor any active heating or cooling systems. High-resolution measurements of air and soil temperatures, relative humidity, solar radiation, and wind speeds were recorded inside Quonset-style passive solar high tunnels, and adjacent open fields, for two growing seasons at two high tunnels in Guelph, Ontario. The side openings on one high tunnel were screened, while the other was left open. Lower than expected frost resistance was observed inside the high tunnels. A one-dimensional parametric energy model was developed to predict air and soil temperatures as a function of weather and high tunnel properties. The model was validated by comparing model predictions of air and soil temperatures to the measurements. A sensitivity study was conducted with the model using different combinations of parameter values to observe the effects of parameter choice on predicted high tunnel microclimate. Parametric models of high tunnel or greenhouse environments were found to be sensitive to choices of model parameters, such as soil, glazing, and thermal properties. The model and data collection was part of a longer study intended to benefit Canadian growers. An ability to accurately predict high tunnel microclimate will help growers choose crops best suited for high tunnels at their location. The data and models resulting from this study will also be useful for identifying methods of reducing energy costs in new high tunnel installations through structural changes and by modifying operating methods.

ACS Style

Shreya Ghose; William Lubitz. Predicting the Interior Conditions in a High Tunnel Greenhouse. Springer Proceedings in Energy 2018, 129 -145.

AMA Style

Shreya Ghose, William Lubitz. Predicting the Interior Conditions in a High Tunnel Greenhouse. Springer Proceedings in Energy. 2018; ():129-145.

Chicago/Turabian Style

Shreya Ghose; William Lubitz. 2018. "Predicting the Interior Conditions in a High Tunnel Greenhouse." Springer Proceedings in Energy , no. : 129-145.

Research paper
Published: 24 December 2018 in Journal of Hydraulic Research
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Archimedes screw generators are an increasingly popular form of small-scale hydropower generation. The power output of an Archimedes screw depends on water fill level within the rotating screw, which is difficult to directly observe. Fill level in a very small screw with a transparent plastic trough has been successfully measured photographically, but this is not practical in larger screws. An alternative, non-optical method was developed using a static pressure sensor in the screw trough to measure fill height during screw operation, which is a new capability. Non-dimensional fill height was measured with an uncertainty of ± 0.072. This method was then used to experimentally investigate overflow in operating screws as a function of fill height. Existing overflow models are based on fill height, screw geometry and inclination angle assuming static water conditions. Results of these experiments showed that overflow in laboratory-scale screws is also dependent on rotational speed.

ACS Style

Kathleen J. Songin; William D. Lubitz. Measurement of fill level and effects of overflow in power-generating Archimedes screws. Journal of Hydraulic Research 2018, 57, 635 -646.

AMA Style

Kathleen J. Songin, William D. Lubitz. Measurement of fill level and effects of overflow in power-generating Archimedes screws. Journal of Hydraulic Research. 2018; 57 (5):635-646.

Chicago/Turabian Style

Kathleen J. Songin; William D. Lubitz. 2018. "Measurement of fill level and effects of overflow in power-generating Archimedes screws." Journal of Hydraulic Research 57, no. 5: 635-646.

Journal article
Published: 26 March 2018 in Journal of Wind Engineering and Industrial Aerodynamics
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The tower supporting an anemometer modifies the local wind field and anemometer measurements. In wind energy resource assessment, tower-induced flow modification contributes a non-negligible amount of uncertainty to the wind resource assessment. The effect of wind speed averaging period on anemometer measurement errors was investigated using high resolution sonic measurements from two sonic anemometers on a tubular tower. Measurements were post-processed into equivalent datasets that differed only by averaging periods. Averaging period only impacted the measured magnitude of the wake, while little effect was seen outside the wake region for data averaging periods between 15 s and 1 h. A model is proposed to remove tower shadow effects from anemometer data using a potential flow solution in the region outside the tower wake and assuming the tower wake is Gaussian and turbulent. An untuned version of the model reproduced the main features of tower-induced flow modification including the turbulent wake, but was not accurate enough to provide a useful correction for wind resource assessment purposes. Fitting model parameters using measured data was found to be a practical way to partially correct wind data from a pair of anemometers in which one fails or becomes unreliable.

ACS Style

William David Lubitz; Andrew Michalak. Experimental and theoretical investigation of tower shadow impacts on anemometer measurements. Journal of Wind Engineering and Industrial Aerodynamics 2018, 176, 112 -119.

AMA Style

William David Lubitz, Andrew Michalak. Experimental and theoretical investigation of tower shadow impacts on anemometer measurements. Journal of Wind Engineering and Industrial Aerodynamics. 2018; 176 ():112-119.

Chicago/Turabian Style

William David Lubitz; Andrew Michalak. 2018. "Experimental and theoretical investigation of tower shadow impacts on anemometer measurements." Journal of Wind Engineering and Industrial Aerodynamics 176, no. : 112-119.

Journal article
Published: 01 March 2018 in Journal of Hydraulic Engineering
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Previous hydraulic studies of Archimedes screw power generators (ASGs) have been mostly at laboratory scale. The validity of scaling up models based on these studies for application in field-scale ASGs has been a major research gap. This study developed a nondimensional artificial neural networks (ANN) model to predict shaft power of an ASG using extensive multiscale data sets. The model was trained using 583 experimental observations from laboratory-scale and field-scale Archimedes screws over a wide range of volume flow rates, operating speeds, and outlet water levels. The input training data was nondimensionalized to allow for scaling between different size screws. The trained ANN model was used to predict the power output of a different ASG with an average error of 6%. It was found that an ANN can be trained to provide reasonably accurate predictions of ASG power if the training data includes a range of ASG sizes.

ACS Style

Andrew Kozyn; Kathleen Songin; Bahram Gharabaghi; William David Lubitz. Predicting Archimedes Screw Generator Power Output Using Artificial Neural Networks. Journal of Hydraulic Engineering 2018, 144, 05018002 .

AMA Style

Andrew Kozyn, Kathleen Songin, Bahram Gharabaghi, William David Lubitz. Predicting Archimedes Screw Generator Power Output Using Artificial Neural Networks. Journal of Hydraulic Engineering. 2018; 144 (3):05018002.

Chicago/Turabian Style

Andrew Kozyn; Kathleen Songin; Bahram Gharabaghi; William David Lubitz. 2018. "Predicting Archimedes Screw Generator Power Output Using Artificial Neural Networks." Journal of Hydraulic Engineering 144, no. 3: 05018002.

Conference paper
Published: 01 January 2018 in Progress in Canadian Mechanical Engineering
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ACS Style

William David Lubitz; Bryan Rubie. Wind Loads On Cyclists Due To Passing Vehicles. Progress in Canadian Mechanical Engineering 2018, 1 .

AMA Style

William David Lubitz, Bryan Rubie. Wind Loads On Cyclists Due To Passing Vehicles. Progress in Canadian Mechanical Engineering. 2018; ():1.

Chicago/Turabian Style

William David Lubitz; Bryan Rubie. 2018. "Wind Loads On Cyclists Due To Passing Vehicles." Progress in Canadian Mechanical Engineering , no. : 1.

Journal article
Published: 03 October 2016 in Applied Energy
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The recent revival of Bayesian optimization has caused widespread utilization of easily accessible and versatile tools in different areas, which involve the search for optimal design or decisions. This method, however, has not yet been explored within the field of renewable energy systems. This study aims to introduce the main benefits of the procedure to the community through the practical task of optimizing the design and operation of the Archimedes screw turbine (AST) in terms of maximizing the total rate of return for a specific installation. The optimal design is presented as a combination of inputs to a software simulation of a true AST. The contribution of this manuscript is threefold: (i) we present the complete procedure needed for optimal sizing of an energy system using Bayesian optimization, (ii) compare various implementations and configurations of the optimization method available under several recent open-source software frameworks and (iii) compare the single-objective with the multi-objective approach to optimization within the same scenario. Our experiments demonstrate superior results using Bayesian optimization in comparison to the standard baseline, both in terms of the time and number of model evaluations required to reach a good solution.

ACS Style

Michal Lisicki; William Lubitz; Graham W. Taylor. Optimal design and operation of Archimedes screw turbines using Bayesian optimization. Applied Energy 2016, 183, 1404 -1417.

AMA Style

Michal Lisicki, William Lubitz, Graham W. Taylor. Optimal design and operation of Archimedes screw turbines using Bayesian optimization. Applied Energy. 2016; 183 ():1404-1417.

Chicago/Turabian Style

Michal Lisicki; William Lubitz; Graham W. Taylor. 2016. "Optimal design and operation of Archimedes screw turbines using Bayesian optimization." Applied Energy 183, no. : 1404-1417.

Chapter
Published: 10 September 2015 in Renewable Energy in the Service of Mankind Vol I
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This study explores the potential to significantly reduce heating costs in northern climates by adding additional layers and types of glazing to simulate greenhouse-like structures with highly insulating roofs that still allow appreciable light transmission. Representative typical meteorological year (TMY) data are used with a one-dimensional multilayer heat transfer model to explore the potential of insulated glazing panels for increasing solar gain. The model was validated against interior temperature and exterior weather data collected at a small unheated greenhouse in winter conditions. It was found that it is possible to reduce winter heating energy costs by using thicker-than-normal insulated glazing, although in practice, energy savings will be offset by added costs of the insulated glazing and additional measures would be needed to minimize summer heat gain. However, the potential for reducing winter heating energy costs suggests potential for highly insulating, semitransparent cladding.

ACS Style

William David Lubitz. Reducing Canadian Greenhouse Energy Costs Using Highly Insulating Glazing. Renewable Energy in the Service of Mankind Vol I 2015, 649 -658.

AMA Style

William David Lubitz. Reducing Canadian Greenhouse Energy Costs Using Highly Insulating Glazing. Renewable Energy in the Service of Mankind Vol I. 2015; ():649-658.

Chicago/Turabian Style

William David Lubitz. 2015. "Reducing Canadian Greenhouse Energy Costs Using Highly Insulating Glazing." Renewable Energy in the Service of Mankind Vol I , no. : 649-658.

Book chapter
Published: 10 September 2015 in Renewable Energy in the Service of Mankind Vol I
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Archimedes screw generators (ASGs) are a form of microhydro power generation that is increasingly being adopted as an alternative renewable energy source. ASGs operate efficiently, even as head approaches zero. A small gap must always exist between the trough and edge of the rotating screw flights to allow screw rotation. This leads to two categories of flow within the screw: the primary flow remains between the helical flights and causes screw rotation, while a secondary leakage flow occurs through the gaps at the screw edges. A high gap leakage flow reduces efficiency because this flow effectively bypasses the working parts of the screw and is lost. An accurate gap leakage model is an essential component of any ASG design model. Current gap leakage models are based on experience with Archimedes screw pumps or are derived from models assuming quasi-static flow through an opening. This experimental study measured the actual leakage flow in an operating laboratory-scale ASG. The fill heights within the buckets were measured using high-speed photography and used to determine bucket volume and therefore non-gap flow. The gap flow is determined based on the difference between the measured total flow through the system and the computed non-gap flow based on the measured fill height and screw speed. The uncertainty of the gap flow is relatively high, since it is calculated based on the difference between two variables with similar magnitude, one of which is calculated based on other measurements. The existing gap flow models did not accurately predict the experimental results. Gap flow was found to be dependent on screw rotation speed, with highest gap flows occurring at intermediate screw rotation speeds. Gap flow reduces to zero as screw rotation speed approaches the maximum possible speed. There is significant uncertainty in the existing gap flow models, and gap flow models constitute one of the largest sources of uncertainty when modeling the performance of ASGs.

ACS Style

Andrew Kozyn; William D. Lubitz. Experimental Validation of Gap Leakage Flow Models in Archimedes Screw Generators. Renewable Energy in the Service of Mankind Vol I 2015, 365 -375.

AMA Style

Andrew Kozyn, William D. Lubitz. Experimental Validation of Gap Leakage Flow Models in Archimedes Screw Generators. Renewable Energy in the Service of Mankind Vol I. 2015; ():365-375.

Chicago/Turabian Style

Andrew Kozyn; William D. Lubitz. 2015. "Experimental Validation of Gap Leakage Flow Models in Archimedes Screw Generators." Renewable Energy in the Service of Mankind Vol I , no. : 365-375.

Journal article
Published: 31 January 2014 in Renewable Energy
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High resolution measurements of wind speed and energy generation from an instrumented Bergey XL.1 small wind turbine were used to investigate the effect of ambient turbulence levels on wind turbine energy production. It was found that ambient turbulent intensity impacts energy production, but that the impact is different at different wind speeds. At low wind speeds, increased turbulence appeared to increase energy production from the turbine. However, at wind speeds near the turbine furling speed, elevated turbulence resulted in decreased energy production, likely to turbulent gusts initiating furling events. Investigation of measurements recorded at 1 Hz showed a time lag of one to 2 s between a change in wind speed and the resulting change in energy production. Transient changes in wind speed of only 1 s duration did not impact energy production, however, longer duration changes in wind speed were tracked reasonably well by energy production.

ACS Style

William David Lubitz. Impact of ambient turbulence on performance of a small wind turbine. Renewable Energy 2014, 61, 69 -73.

AMA Style

William David Lubitz. Impact of ambient turbulence on performance of a small wind turbine. Renewable Energy. 2014; 61 ():69-73.

Chicago/Turabian Style

William David Lubitz. 2014. "Impact of ambient turbulence on performance of a small wind turbine." Renewable Energy 61, no. : 69-73.

Journal article
Published: 31 January 2014 in Journal of Solar Energy Engineering
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A small wind turbine blade was designed using blade element momentum (BEM) method for a three bladed, fixed pitch 1 kW horizontal axis wind turbine. The new blades were fabricated, fit to a Bergey XL 1.0 turbine, and tested using a vehicle-based platform at the original designed pitch angle, plus with 5 deg and 9 deg of additional pitch. The new blades had better aerodynamic performance than the original Bergey XL 1.0 blades at high speed, but in some cases at lower speeds the original blades performed better. The results demonstrated that selecting the blade pitch angle on a rotor is a tradeoff between starting performance and power output in high winds. The BEM simulations were evaluated against the test data and demonstrated that the BEM simulations predicted the rotor performance with reasonable accuracy.

ACS Style

Qiyue Song; William David Lubitz. Design and Testing of a New Small Wind Turbine Blade. Journal of Solar Energy Engineering 2014, 136, 034502 .

AMA Style

Qiyue Song, William David Lubitz. Design and Testing of a New Small Wind Turbine Blade. Journal of Solar Energy Engineering. 2014; 136 (3):034502.

Chicago/Turabian Style

Qiyue Song; William David Lubitz. 2014. "Design and Testing of a New Small Wind Turbine Blade." Journal of Solar Energy Engineering 136, no. 3: 034502.

Original articles
Published: 02 January 2014 in International Journal of Sustainable Energy
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Knowledge of the wind resource above peaked roofs is necessary to determine whether installing small wind turbines on low-rise peaked roof buildings is feasible. The wind characteristics at a representative peaked roof barn in southern Ontario, Canada were investigated using a boundary layer wind tunnel and computational fluid dynamics. Field measurements at the barn were collected using sonic anemometers and compared with the simulation results. Wind speed amplification was confined to a region immediately above the roof and was relatively low for wind energy purposes. The presence of nearby trees or buildings adversely impacted wind speed amplification. Considering only wind-related factors, the placing of micro-wind turbines on roof peaks may be warranted. However, if sufficient space is available, it is recommended to place small turbines on a tower rather than on the peaked roof of a low-rise building.

ACS Style

Rohan Hakimi; William David Lubitz. Wind environment at a roof-mounted wind turbine on a peaked roof building. International Journal of Sustainable Energy 2014, 35, 1 -18.

AMA Style

Rohan Hakimi, William David Lubitz. Wind environment at a roof-mounted wind turbine on a peaked roof building. International Journal of Sustainable Energy. 2014; 35 (2):1-18.

Chicago/Turabian Style

Rohan Hakimi; William David Lubitz. 2014. "Wind environment at a roof-mounted wind turbine on a peaked roof building." International Journal of Sustainable Energy 35, no. 2: 1-18.