Browsing by Subject "dilution"
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Item Forced Dispersion of Liquefied Natural Gas Vapor Clouds with Water Spray Curtain Application(2011-02-22) Rana, Morshed A.There has been, and will continue to be, tremendous growth in the use and distribution of liquefied natural gas (LNG). As LNG poses the hazard of flammable vapor cloud formation from a release, which may result in a massive fire, increased public concerns have been expressed regarding the safety of this fuel. In addition, regulatory authorities in the U.S. as well as all over the world expect the implementation of consequence mitigation measures for LNG spills. For the effective and safer use any safety measure to prevent and mitigate an accidental release of LNG, it is critical to understand thoroughly the action mechanisms. Water spray curtains are generally used by petro-chemical industries to prevent and mitigate heavier-than-air toxic or flammable vapors. It is also used to cool and protect equipment from heat radiation of fuel fires. Currently, water spray curtains are recognized as one of the economic and promising techniques to enhance the dispersion of the LNG vapor cloud formed from a spill. Usually, water curtains are considered to absorb, dilute, disperse and warm a heavier-than-air vapor cloud. Dispersion of cryogenic LNG vapor behaves differently from other dense gases because of low molecular weight and extremely low temperature. So the interaction between water curtain and LNG vapor is different than other heavier vapor clouds. Only two major experimental investigations with water curtains in dispersing LNG vapor clouds were undertaken during the 1970s and 1980s. Studies showed that water spray curtains enhanced LNG vapor dispersion from small spills. However, the dominant phenomena to apply the water curtain most effectively in controlling LNG vapor were not clearly demonstrated. The main objective of this research is to investigate the effectiveness of water spray curtains in controlling the LNG vapor clouds from outdoor experiments. A research methodology has been developed to study the dispersion phenomena of LNG vapor by the action of different water curtains experimentally. This dissertation details the research and experiment development. Small scale outdoor LNG spill experiments have been performed at the Brayton Fire Training Field at Texas A&M University. Field test results regarding important phenomena are presented and discussed. Results have determined that the water curtains are able to reduce the concentration of the LNG vapor cloud, push the vapor cloud upward and transfer heat to the cloud. These are being identified due to the water curtain mechanisms of entrainment of air, dilution of vapor with entrained air, transfer of momentum and heat to the gas cloud. Some of the dominant actions required to control and disperse LNG vapor cloud are also identified from the experimental tests. The gaps are presented as the future work and recommendation on how to improve the experiments in the future. This will benefit LNG industries to enhance its safety system and to make LNG facilities safer.Item Pregnancy Rates in Mares Inseminated with 0.5 or 1 Million Sperm Using Hysteroscopic or Transrectally Guided Deep-Horn Insemination Techniques(2013-11-08) Hayden, Shelby ShalenePlacement of sperm deep in the equine uterine horn allows fewer sperm to be inseminated while maintaining acceptable fertility, and has been promoted for use in circumstances when fertility would be expected to be low if standard insemination were used (e.g. semen from a subfertile stallion, or frozen-thawed semen). Two main deep- horn insemination techniques, transrectally guided (TRG) and hysteroscopic (HYS) insemination, have been developed for this purpose; however, there is some controversy regarding their comparative efficacy. This study was conducted to compare pregnancy rates when mares were inseminated by TRG or HYS, utilizing sperm numbers approaching and under the threshold for maximal fertility, resulting in reduced fertility. Pregnancy rates were not different between HYS and TRG techniques when 1 x 106 or 0.5 x 106 sperm were inseminated. Combined pregnancy rates for the two techniques were also not different. Pregnancy rates using a subthreshold number of sperm were not significantly affected by a deep-horn insemination technique. Dilution of semen to less than 20 x 106 sperm/mL has been reported to decrease semen quality in multiple species, a phenomenon known as the semen ?dilution effect.? The sperm concentrations utilized in Experiment 1 were 5 and 2.5 x 106/mL (1 and 0.5 x 106 sperm doses, respectively). This experiment was performed to evaluate whether the lower pregnancy rates obtained with 0.5 x 106 sperm was due to lower quality plasma membrane integrity (PMI) and sperm motion characteristics (TMOT, PMOT, VCL, VAP, VSL, STR). Treatments evaluated included 2.5 x 106 sperm/mL with the addition of 0, 7.5, and 25% seminal plasma, 30 x 106 sperm/mL, and 3:1 extender: semen. The 2.5 x 106 sperm/mL treatments have lower initial PMI, TMOT, and PMOT, but they maintain their initial quality following 24 and 48 h of cool-storage. The sperm velocity and straightness parameters suggest that sperm swim faster but have a more circular pattern as seminal plasma increases to 25% at a given concentration. Based on the findings from this experiment, the semen ?dilution effect? may not significantly alter stallion sperm characteristics when a commercially-available semen extender is used for semen dilution.