An Experimental Comparison of the Performance of Two Impulse Micro-Hydro Turbine Impellers

The goal of this project was to measure the performance of two micro-hydro Turgo Impulse Turbine Impellers. In 2014, Hydropower accounted for 6% of total electric power produced and 48% of electricity produced by renewable sources in the United States. Micro-hydro power is an established, robust, and versatile technology that can help society produce electric power without the emission of greenhouse gases and with minimal environmental impact. Competition from other renewable energy sources is causing the operational efficiency and power production of micro-hydro turbines to become increasingly important. This competition puts pressure on manufacturers to improve the quality of their turbine designs and manufacturing methods. Computational fluid dynamics (CFD), combined with numerical methods and increased computing power, have become more widely used tools in the past several decades for design improvement. However, empirically derived performance data is still needed to validate modeling improvements and support further development of hydropower technology. Two impellers were chosen for study because they were used in an operational turbine system that the experiments were modeled after. The first impeller was designed and partially manufactured by Hartvigsen Hydro and assembled by Preston Machine, Inc. The second impeller had been in operation in the turbine system for several years and showed signs of wear. The blades on the two impellers were shaped very differently due to having completely different manufacturers. A test setup was designed and constructed to measure the overall efficiency and power output of both impellers. Two types of performance experiments were conducted. The first experiment determined the most efficient setting for the inlet nozzles which are used to increase the kinetic energy of the water prior to impinging on the turbine impeller. The second experiment measured the efficiency and power output of each impeller while varying the flow rate and shaft speed for each of two impellers. The results were analyzed and displayed as three dimensional maps for graphical interpretation of turbine performance as conditions were varied. The experiments indicate that the new impeller (impeller A) operated most efficiently with a peak efficiency 84.6% (with mechanical losses excluded). The older impeller (impeller B) reached a peak efficiency of 74.8%. Both impellers produced approximately the same amount of shaft power (28.6 hp with mechanical losses included) at their peak operating points. The experiments indicated that both turbines were sensitive to varying conditions and properly managing those conditions is necessary to obtain reliable and efficient energy output over a long operational lifetime

Sod webworm (Lepidoptera: Pyralidae: Crambinae) moths collected in light traps

Thirteen species of sod webworm moths were collected during 1968. Distinct differences in fijght dates occurred among the species. Trap data indicated that seven species were univoltine while six were most likely multivoltine. Sod webworm species collected as adults in light traps from May to October: Pediasia trisecta, P mutabilis, Chrysoteuchia topiaria, Agriphila vulgivagella, A. ruricolella, Microcrambus elegans, Argyria nivalis, Crambus alboclavellus, C. praefectellus, C. laquetellus, C. leachellus, C. satrapellu

Training Opportunities Available to Ohio Lake Erie Basin Local Decision-makers Regarding the Economic and Fiscal Benefits of Coastal and Watershed Stewardship

This paper presents new knowledge about the current status of training on the economic value of stewardship practices in the Ohio Lake Erie basin. Local decision-makers shape coastal and watershed conditions but often do not appreciate the economic, fiscal, and ecological benefits that could be gained from sound stewardship practices. This study investigated the information and training about economic benefits available in the Ohio Lake Erie basin. Training providers and technical assistance professionals helped identify key training needs and challenges to decision-maker awareness of benefits. We found relatively few organizations offering training that incorporate economic or fiscal benefits into their curricula. Within these programs, stormwater management and tourism were the most popular training topics among local decision-makers. Regarding target audiences, training providers noted that public sector participants tended to be interested in the fiscal (tax revenue and public spending) impacts of regulations and in economic development. Our analysis suggests a need to document the economic and fiscal benefits and costs to existing practices in the Lake Erie basin to provide case studies and examples for peer-to-peer education for local decision-makers. The results suggest a need for increased collaboration among training providers and educational institutions in the Lake Erie basin to develop case studies or fact sheets of benefits and costs. The results also suggest that creating a technical advisory network concerning economic benefits and costs would provide a useful service to local decision-makers

Hatching of Sod Webworm Eggs in Relation to Low and High Temperatures

Eggs of 12 species of sod webworm were exposed for various periods to temperatures of 0, 10, and 45°C. Hatchability was compared with control eggs kept at 25°C. Short exposures to any temperature did not significantly affect percent hatch. Prolonged exposure resulted in a significant decrease in hatchability for several species at 0° and for all species at 45°C. There was a significant difference in hatchability between the 3 generations of Crambus teterrellus (Zincken) and of Pediasia trisecta (Walker) at extreme temperatures. Populations of Agriphila ruricolella (Zeller), collected at 2 elevations, differed significantly in hatching percentage and developmental rate

Low Voltage Nanoelectromechanical Switches Based on Silicon Carbide Nanowires

We report experimental demonstrations of electrostatically actuated, contact-mode nanoelectromechanical switches based on very thin silicon carbide (SiC) nanowires (NWs). These NWs are lithographically patterned from a 50 nm thick SiC layer heteroepitaxially grown on single-crystal silicon (Si). Several generic designs of in-plane electrostatic SiC NW switches have been realized, with NW widths as small as ~20 nm and lateral switching gaps as narrow as ~10 nm. Very low switch-on voltages are obtained, from a few volts down to ~1 V level. Two-terminal, contact-mode “hot” switching with high on/off ratios (>10^2 or 10^3) has been demonstrated repeatedly for many devices. We find enhanced switching performance in bare SiC NWs, with lifetimes exceeding those based on metallized SiC NWs

Hatching of Sod Webworm Eggs in Relation to Low Temperatures

Eggs of Chrysoteuchia topiaria (Zeller), Crambus pascuellus floridus (Zeller), and Pediasia trisecta (Walker) were exposed to temperatures of 25, 15, 10, 4, and –10°C. Only those of P. trisecta hatched after exposure to 4°C for 30 days, while none hatched after exposure to –10°C. Eggs of none of the species hatched after exposure to 4 and 10°C for 60 days. Pre-exposure and post-exposure conditioning had no significant effect on percent hatch of P. trisecta eggs, while length of exposure period had a significant effect

Seasonal Abundance and Distribution of Benthic Fauna within a Pond

A Tennessee pond was sampled weekly from June 18 to August 20, 1968, to determine quantitative differences among benthic organisms in sampling depths and dates. Annelids (Oligochaeta), Chironomidae larvae, and Chaoboridae larvae were the dominant organisms collected. Preferred depths existed for each group of organisms. Chaoboridae and Chironomidae exhibited distinct seasonal variations in numbers, with the population decreasing throughout the summer. Chaoboridae were the most and Chironomidae the least numerous of the 3 groups

Intrinsic Fano factor of nuclear recoils for dark matter searches

Nuclear recoils in germanium and silicon are shown to have much larger variance in electron-hole production than their electron-recoil counterparts for recoil energies between 10 and 200\,keV. This effect--owing primarily to deviations in the amount of energy given to the crystal lattice in response to a nuclear recoil of a given energy--has been predicted by the Lindhard model. We parameterize the variance in terms of an intrinsic nuclear recoil Fano factor which is 24.3$\pm$0.2 and 26$\pm$8 at around 25\,keV for silicon and germanium respectively. The variance has important effects on the expected signal shapes for experiments utilizing low-energy nuclear recoils such as direct dark matter searches and coherent neutrino-nucleus scattering measurements.Comment: 9 pages, 6 figure