Enabling Feasibility Assessment of Solar Thermal Energy Systems for Industrial Process Heating Applications

Existing studies on industrial heat demand have shown that more than 50% of the industrial process heat demand is in the range of low (<60 °C), medium (60-150 °C), and medium-high (<250 °C) temperatures. Most of the manufacturing industries across the world depend on combustion of carbon-based fossil fuels, either partially or fully, for the generation of process heat. Commercially available solar thermal technologies are capable of generating a significant portion of low temperature process heat, which would reduce the use of fossil fuels, reducing the associated energy cost volatility and carbon emissions. Moreover, the improvement and proliferation of solar collector technology, and the introduction of solar-friendly policies in recent years have made solar thermal systems economically competitive investments with long-term, inflation-protected returns. Despite this tremendous benefit, the deployment of solar thermal systems for industrial process heating is surprisingly low. The major barriers for the deployment of solar thermal energy systems for industrial process heating include a poor understanding of operational characteristics of solar thermal systems at different heating loads and insolation values, and a lack of robust and cost-effective design decision support tools for appraising the merits of individual projects. The research presented herein aims to contribute in lowering the barrier for industrial scale deployment of solar thermal energy systems through: 1) Explanation of the characteristics performance of a solar flat-plate thermal system with backup gas heaters (a solar/gas hybrid heating system) at different heating loads and insolation values that approximate scaled process heating requirements of different industrial processes via an experimental study, 2) Identification of process heating temperatures that might be economically served with solar/gas hybrid heating systems based on site insolation characteristics, collector characteristics, and gas prices, 3) Identification of solar/gas hybrid heating system configurations that would provide higher system efficiency when combining solar and gas heating modes, and 4) Development and demonstration of design decision support tools for feasibility assessment of solar thermal energy systems. The outcomes of this research will enable engineers and industry decision-makers to analyze what-if scenarios to evaluate the feasibility of solar thermal systems for their applications based on site-specific data, while reducing cost and demand of technical resources required to perform the feasibility assessment

Factors affecting livestock depredation by snow leopards (Panthera uncia) in the Himalayan region of Nepal

The snow leopard (Panthera uncia) found in central Asia is classified as vulnerable species by the International Union for Conservation of Nature (IUCN). Every year, large number of livestock are killed by snow leopards in Nepal, leading to economic loss to local communities and making human-snow leopard conflict a major threat to snow leopard conservation. We conducted formal and informal stakeholder’s interviews to gather information related to livestock depredation with the aim to map the attack sites by the snow leopard. These sites were further validated by district forest office staffs to assess sources of bias. Attack sites older than 3 years were removed from the survey. We found 109 attack sites and visited all the sites for geo location purpose (GPS points of all unique sites were taken). We maintained at least a 100 m distance between attack locations to ensure that each attack location was unique, which resulted in 86 unique locations. A total of 235 km2 was used to define livestock depredation risk zone during this study. Using Maximum Entropy (MaxEnt) modeling, we found that distance to livestock sheds, distance to paths, aspect, and distance to roads were major contributing factors to the snow leopard’s attacks. We identified 13.64 km2 as risk zone for livestock depredation from snow leopards in the study area. Furthermore, snow leopards preferred to attack livestock near livestock shelters, far from human paths and at moderate distance from motor roads. These identified attack zones should be managed both for snow leopard conservation and livestock protection in order to balance human livelihoods while protecting snow leopards and their habitats

Thermal Performance Evaluation of a Residential Solar/Gas Hybrid Water Heating System

In climate regions with lower average daily solar radiation, such as the Pacific Northwest, a solar energy collector might not economically satisfy year-round domestic water heating demands, requiring an auxiliary unit, such as a natural gas water heater. Previous studies of such hybrid systems have shown that the efficiencies achieved while running in combined solar/gas mode was lower than expected. This inefficiency was attributed to a reduction in gas burner efficiency when the process fluid was partially pre-heated by the solar input. To predict the actual energy and cost savings under various design conditions, the performance of solar/gas hybrid systems must be better understood. In this work, the performance of a commercial hybrid solar/gas system is experimentally characterized to evaluate individual component and overall system efficiency. The hybrid water heating system consisted of three flat plate collectors arranged in series (total area = 6.44 m2), and a 22.3 kW natural gas burner. Under different temperature lifts and solar insolation values, the system was operated at three different modes of heating: solar, gas, and combined solar/gas mode. Efficiency value for each mode was calculated. Based on the experimental efficiency results, a configuration that would provide higher efficiency for combined solar/gas heating is suggested

Investigation of the combined efficiency of a solar/gas hybrid water heating system

In climate regions with large seasonal variations in solar radiation, such as the Pacific Northwest of the United States, a solar thermal energy collector might not economically satisfy year-round domestic water heating demands, requiring an auxiliary unit, such as a natural gas-fired water heater. Previous studies have shown that the burner efficiency of a gas-fired water heater varies depending on the log-mean temperature difference between the cold fluid (water) and the hot fluid (combustion gases). In a solar/gas hybrid water heating system, where solar collectors are used in conjunction with a gas-fired heater, the partial heating of water provided by solar input reduces the log-mean temperature difference value for the gas heater, reducing the efficiency of the gas burner. Since this efficiency reduction varies depending on the amount of pre-heating provided by solar energy input, it is difficult to accurately predict the actual cost and energy savings offered by solar/gas hybrid water heaters in different climates and operation scenarios. Hence, to predict the actual energy and cost savings under various design conditions, the performance of solar/gas hybrid systems must be better understood. The objective of this work is to experimentally determine the thermal performance of a solar/gas water hybrid water heating system with a 6.44 m2 flat plate solar collector array and a 22.3 kW natural gas burner in Corvallis, Oregon, USA. Under different temperature lifts and solar insolation values, the system was operated at three different modes of heating: solar, gas, and combined solar/gas mode. The overall system thermal efficiency value for each mode is calculated. The efficiency of the solar collector heating system was found to be 41.97%, 39.82%, and 35.05% at initial water temperature of 20, 30, and 51.5 °C, respectively. For initial water temperatures of 20, 30, and 51.5 °C, the efficiency of the gas burner was found to be 69.2%, 66.4%, and 65.5% at the HHV, and 76.7%, 73.6%, and 72.6% at the LHV of natural gas, respectively. In the combined solar/gas heating mode, the efficiency of the gas burner decreased with increasing solar fraction. For solar fractions of 4.93%, 9.40%, 11.39%, and 14.27%, the efficiency of the gas burner in terms of the HHV of natural gas was found to be of 69.08%, 66.80%, 66.17%, and 65.18%, respectively. Based on the experimental results, a configuration that would provide higher overall system efficiency for combined solar/gas heating is suggested

水制工を有する蛇行水路の水成地形特性に関する研究

京都大学0048新制・課程博士博士(工学)甲第22049号工博第4630号新制||工||1722(附属図書館)京都大学大学院工学研究科社会基盤工学専攻(主査)教授 中川 一, 教授 藤田 正治, 准教授 川池 健司学位規則第4条第1項該当Doctor of Philosophy (Engineering)Kyoto UniversityDFA

Investigating the validity of Telemac2d-Sisyphe model for predicting bed evolution in meandering channels

HydrodynamicsAbstrac

Evolution of Alluvial Meandering Channels: Comparison between Laboratory Experiments and Natural Channels

The current study examines the evolution of alluvial meandering channels based on the laboratory experiments as well as field study. Experiments were conducted in erodible meandering channels to represent the natural scenario. Channel planform, as well as bed evolution, were analyzed. In the case of natural channels, time series satellite images were analyzed to understand the channel planform behaviour and bank erosion characteristics were analyzed through the real field data and photos. Results showed that the channel evolution characteristics vary from one alluvial meandering channel to another depending upon various channel parameters. It was found that low sinuosity channels and newly developed meander bends have higher tendency to migrate as well as undergo rapid channel adjustment. Bank protection counter-measures were effective in minimizing the bank erosion. At the same time, they tend to shift the point of erosion from one location to another

Numerical Study on the Hydro-Morphological and Bank Erosion Characteristics of Uji River, Japan

We performed numerical study on Uji River with an objective to analyze the channel hydromorphological characteristics including bank erosion process. Simulation results suggested that the overall channel evolution is insignificant but the bank erosion is dominant at several locations. It was also concluded that the bank erosion is mainly caused by the undercutting of the bank toe due to the low flow condition which induce high bed shear stress and high near bank velocity. With higher flow discharge, the zone of maximum velocity tend to shift more towards the channel center. Results of the prediction of bank erosion indicated that fluvial erosion due to the scour near the bank toe is dominant at most of the locations in Uji River