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Efficiency of energy resource use is a key factor for a sustainable energy future. By matching the exergy levels of supply and demand, Energy Quality Management (EQM) of building energy supply systems may achieve more efficient use of energy resources. Beyond this, environmental impact of energy supply systems is another essential issue. This work addresses the influence of EQM on CO 2 emissions in the operation optimization of a Distributed Energy System (DES). A multi-objective linear programming problem is formulated to reduce energy costs and increase the overall exergy efficiency. Total CO 2 emissions are evaluated for the optimized operation strategies of the DES. The operators of the DES can choose the operation strategy from the Pareto front, based on their priorities and also aware of effects on CO 2 emissions. Results demonstrate more efficient use of energy resources and reduction in CO 2 emissions through EQM, as compared with conventional energy supply systems.

Abstract Dynamic modeling of HVAC system is extremely important for control analysis toward building energy saving. In order to provide researchers a simulation platform to analyze different control strategies, this paper introduces a simulation platform with customized Simulink block library based on dynamic HVAC component model. As an initiating effort, the current simulation platform is composed of basic modular HVAC components, including conduit, damper/valve, fan/pump, flow merge, flow split, heating coil, cooling coil, and zone. These modules are developed into Simulink customized blocks. The simulation platform is capable to calculate the flow rates of fresh air, exhaust air, and return air based on system characteristic and fan curve with customizable basic/advanced control strategies. A case study is proposed using single-zone, constant volume system by comparing the uncontrolled, fixed temperature and damper position controlled, and schedule based reset controlled cases. The simulation result proves that schedule based temperature and damper position reset has a significant impact on energy saving for both heating and cooling seasons. This simulation platform can be especially useful for analyzing the dynamic performance of different HVAC control strategies.

Abstract In this paper, we investigate distributed thermal-electrochemical modeling of a Lithium-Ion battery cell to include the effect of temperature distribution across the thickness of the cell as a first step to study the module level temperature distribution at high charging rates. Most recent works have focused on lumped thermal models for a Li-Ion cell which ignore any temperature differential across cell thickness. However, even a small temperature differential across cell thickness at the cell level can contribute to significant temperature differential in the thickness direction of stacked-up Li-Ion cells at the module level. Such temperature differential can potentially impact the battery charging control system, especially at high charging rates. Here, the thermal-electrochemical partial differential and algebraic equations for a Li-ion cell are solved via a spatial finite difference method. Simulation results show that the temperature differentials over the cell thickness at the cell level are not insignificant, particularly at high charging rates.

Abstract Global warming is a major challenge that we are facing today that involves the emission of harmful greenhouse gases like carbon dioxide (CO 2 ) into the atmosphere. Pressurized pipelines are considered to be the most efficient and reliable way to transport CO 2 due to the high density and low viscosity of CO 2 . Any accidental discharge from such high pressure pipelines may result in significant damage to the ambient atmosphere and a powerful threat to human health. The unusual phase transition behavior of CO 2 post leak can pose challenging risks for modeling the safe transportation of CO 2 , which is one of the most critical process design considerations in a carbon capture and storage (CCS) area. The current consequence model described in this work predicts the transient jet release rates and the concentration variations of pure CO 2 over a given period of time and distance in Fluent 16.2. This has been validated against experimental work carried out by BP’s DF1 project at the Spadeadam site. The work has been extended to study the effect of terrain on the final downwind concentration of CO 2 . This consequence model could successfully predict the minimum safe distances to populated areas and can be used as a risk assessment tool for planning emergency response in case of pipeline leakage during CO 2 transport.

AbstractCoral reefs across the world have been seriously degraded and have a bleak future in response to predicted global warming and ocean acidification (OA). However, this is not the first time that biocalcifying organisms, including corals, have faced the threat of extinction. The end‐Triassic mass extinction (200 million years ago) was the most severe biotic crisis experienced by modern marine invertebrates, which selected against biocalcifiers; this was followed by the proliferation of another invertebrate group, sponges. The duration of this sponge‐dominated period far surpasses that of alternative stable‐ecosystem or phase‐shift states reported on modern day coral reefs and, as such, a shift to sponge‐dominated reefs warrants serious consideration as one future trajectory of coral reefs. We hypothesise that some coral reefs of today may become sponge reefs in the future, as sponges and corals respond differently to changing ocean chemistry and environmental conditions. To support this hypothesis, we discuss: (i) the presence of sponge reefs in the geological record; (ii) reported shifts from coral‐ to sponge‐dominated systems; and (iii) direct and indirect responses of the sponge holobiont and its constituent parts (host and symbionts) to changes in temperature andpH. Based on this evidence, we propose that sponges may be one group to benefit from projected climate change and ocean acidification scenarios, and that increased sponge abundance represents a possible future trajectory for some coral reefs, which would have important implications for overall reef functioning.

Proton nuclear magnetic resonance (NMR) spectroscopy was used to follow glucose metabolism in Crithidia luciliae. Parasites were grown aerobically and anaerobically in culture, with glucose as the major carbon source and 1H NMR spectra were acquired for the cell free medium. The 1H NMR resonances of metabolites utilised and produced during cell growth were identified by difference spectroscopy, and quantitated from standard curves using 3-trimethylsilyl propionate-2,2,3,3-d4 sodium salt as an internal standard. The major metabolites produced by C. luciliae grown aerobically on 8 mM glucose were succinate, pyruvate, acetate and ethanol, in final concentrations in the media when the cells entered stationary phase of 8.5 +/- 0.5, 5.0 +/- 0.3, 2.1 +/- 0.2 and 2.5 +/- 0.6 mM, respectively. The production of succinate and pyruvate, but not acetate and ethanol, followed closely the growth curve of the parasites. Succinate was also measured enzymically and glucose using an autoanalyser. In both cases the results correlated well with the NMR data. The amounts of end products formed were greater than could be accounted for by the utilisation of glucose or any other metabolite observable in the 1H NMR spectra. There was approximately one extra atom of carbon for each molecule of succinate formed, supporting the view that succinate is produced via phosphoenolpyruvate carboxykinase and carbon dioxide fixation. Anaerobically the same major metabolites were produced, but with a decreased ratio of succinate to acetate and ethanol. The formation of glycerol from glucose was not observed under these conditions.

Abstract As the adverse effects of global warming become increasingly apparent, the need for low-GWP solutions in the HVAC&R industry is its highest in decades. Alternative working fluids, including natural refrigerants such as Carbon Dioxide (CO2), and high efficiency systems are ways to mitigate the negative environmental impact of refrigeration systems. Researchers have focused on investigating several transcritical CO2 cycles for supermarket and transport applications. Yet, a systematic experimental comparison between multiple advanced cycle architectures is still lacking. To this end, a novel test stand capable of comparing two methods of expansion as well as open-economization at one or both evaporator pressure levels, allowing six cycle configurations that represent much of the state-of-the-art has been developed. Cycle designs, thermodynamic modeling for component sizing, and experimental validation of test stand operation and energy balances are discussed in-depth. Limitations and modifications to the test stand are discussed, as are next steps.

Many signal validation methods detect sensor faults by comparing signal measurements with their estimates reconstructed from other correlated signals. For these methods, one faulty signal may cause all the other signals that use the faulty signal as an input in signal estimation to be un-correctly reconstructed and subsequently falsely identified as faulty too. This phenomenon is called fault propagation and can produce excessive false alarms in signal validation. This paper presents a general sub-grouping technique that uses specially designed intersections between sub-groups to eliminate the false alarms caused by fault propagation. Two methods are developed based upon this technique. Demonstration shows that both methods can dramatically reduce the occurrence of fault-propagation-caused false alarms in signal validation.