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To mitigate ammonia (NH 3 ) emissions from pig production and understand dynamic emission profiles, reduced dietary crude protein (CP) with amino acid supplementation was studied with 720 pigs in a 12-room research building for 155 days that covered from weaned to finishing stages. The pigs were divided into three 4-room groups and fed with 2.1–3.8% reduced CP (T 1 ), 4.4–7.8% reduced CP (T 2 ), and standard (control) diets, respectively. Compared with the control group, T 1 and T 2 decreased manure volumes and manure NH 4 + -N concentrations. Group-mean NH 3 emission from the control group was 68.9 g d −1 AU −1 (AU = 500 kg live mass). Emissions from T 1 (46.7 g d −1 AU −1 ) and T 2 (29.8 g d −1 AU −1 ) were reduced by 33.0% and 57.2% ( p < 0.05), respectively. Dynamic peak NH 3 emissions appeared during the third nursery phase for T 1 and T 2 , but delayed to the first grower phase for the control group. [ABSTRACT FROM AUTHOR]

Ventilation rate is equally important as pollutant concentration in aerial emission quantification, but is technically challenging to determine for animal buildings. A simple and reliable method using 240-VAC to 6-VDC unregulated adapters to monitor 24 single-speed wall-mount ventilation fans was applied in a 12-room swine environmental research building. A portable Wall Fan Tester (WFT), consisting of nine equally-distanced impeller anemometers, was designed and developed to measure airflow rates of the wall fans of 508-mm and 356-mm diameters. Fan ventilation rates were tested using the WFT at 5 or 6 static pressures from −1.8 to −133.9 Pa and power voltages from 185 to 245 VAC at 15-VAC increments in five fan test sessions. Fan ventilation models were developed using a single independent variable (static pressure) and two independent variables (static pressure and fan power voltage). The innovative system and methodology considerably improved ventilation rate quantification for the 12 rooms. The study also found that the wall fans in the building delivered 16.9–40.1% less ventilation under different static pressures compared with the fan specifications. There were 17–29% ventilation rate variations among identical fans in different rooms. Daily power supply voltages to the fans often fluctuated for 3–6%, which could introduce errors in ventilation calculations if not taking them into account. Cross-sectional airflow profiles were not always symmetric and there were backflows in some sub-areas for the 356-mm fan inlet at conditions of low power voltages and high negative static pressures. [ABSTRACT FROM AUTHOR]

Air pollutants emitted from confined animal buildings can cause environmental pollution and ecological damage. Long-term (>6 months) and continuous (or high frequency) monitoring that can reveal seasonal and diurnal variations is needed to obtain emission factors and characteristics about these pollutants. A two-year continuous monitoring of ammonia (NH 3 ), hydrogen sulfide (H 2 S), carbon dioxide (CO 2 ) and particulate matter (PM 10 ) emissions from two 218,000-hen high-rise layer houses (H-A and H-B) in Indiana, USA was conducted from June 2007 to May 2009. Gaseous pollutant concentrations were measured with two gas analyzers and PM 10 concentrations were measured with three Tapered Element Oscillating Microbalances. The operation and performance of ventilation fans were continuously monitored with multiple methods. Only the emission rates calculated with valid data days (days with more than 18 h, or 75%, of valid data) are reported in this paper. The two-house and two-year mean ± standard deviation emissions per day per hen for NH 3 , H 2 S, CO 2 , and PM 10 were 1.08 ± 0.42 g, 1.37 ± 0.83 mg, 76.7 ± 14.6 g, and 20.6 ± 22.5 mg, respectively. Seasonal emission variations were demonstrated for NH 3 and CO 2 , but not evident for H 2 S and PM 10 . Ammonia and CO 2 emissions were higher in winter than in summer. Significant daily mean emission variations were observed for all four pollutants between the two houses (P < 0.05), and between the two years from the same house (P < 0.01) except for CO 2 at one house. Carbon dioxide originated from manure decomposition was >9% of that from bird respiration. Emissions of CO 2 during molting were about 80% of those during normal egg production days. Emissions of H 2 S were not a major concern due to their very low quantities. Emissions of PM 10 were more variable than other pollutants. However, not all of the emission statistics are explainable. [ABSTRACT FROM AUTHOR]

Abstract: Air samples of a municipal solid waste power plant were collected for the investigation from chimney, discharge workshop, boundary site and downwind receptor sites during regular operational period as well as overhaul period. In the regular operational period, 29 VOC species were detected from the discharge workshop and 25 VOC species from the plume of chimney. Average total VOC concentration at the discharge workshop site was 57.70±19.55 μg/m3 which was primarily composed of aromatic compounds and alkanes, but it was up to 270.63±2.84 μg/m3 in the plume of chimney which mainly included aromatic compounds and halohydrocarbons. In the overhaul period, average total VOC concentration was 59.70±0.91 μg/m3 in the discharge workshop and 326.35±151.68 μg/m3 in the chimney. Aromatics, halohydrocarbons and alkanes were indentified as the significant VOC fingerprints among which chlorobenzene and tetrachloroethylene were two unique VOC molecular markers of the power plant. Moreover, the VOC emission inventory of Chinese MSWI power plant was estimated approximately, it indicated that annual emission amount of the VOCs from the nationwide MSWI power plants reached 38.6tons in 2005 and would rise to 81.80 tons in the end of 2010. [Copyright &y& Elsevier]

NaCl–CaCl 2 molten salt is considered as a promising high-temperature heat transfer and storage fluid for advanced nuclear power plants and concentrating solar power plants in the field of renewable energy utilization. However, the comprehensive physical properties and their microscopic mechanisms for the molten NaCl–CaCl 2 are failed to be measured accurately due to the extremely measuring condition. In this work, the ab-initio molecular dynamics simulation is used to investigate its microstructures and thermophysical properties for entire operating temperatures. It reveals that ion clusters are formed in terms of three for face-sharing, two for edge-sharing, and one for corner-sharing Cl− ions between the coordination shells of two neighboring cations. The coordination numbers of Na+-Cl- and Ca2+-Cl- ion pairs decrease from 5.88 to 6.46 at 783 K to 5.33 and 6.02 at 1173 K respectively. Meanwhile, the reliable and meaningful values of densities, ion self-diffusion coefficients, viscosities, and thermal conductivities were evaluated from 783 to 1173 K. It suggests that the distances and interactions between ions pairs determine thermodynamic properties directly. The ab-initio molecular dynamics simulation is proved to be an effective way to obtain the essential data for the designs of heat transfer and thermal energy storage systems in practical applications. • Ab-initio molecular dynamics simulations are applied for NaCl–CaCl 2. • Approach-to-equilibrium molecular dynamics method is used for thermal conductivity. • The correlation between microstructures and thermophysical properties are studied. • The distances and interactions between ion pairs determine its properties. [ABSTRACT FROM AUTHOR]

Antibiotic use and ammonia (NH 3) emissions during animal production are two environmental issues of worldwide concern. However, the role of antibiotics on NH 3 emissions is still unknown. This study evaluated the effects of rearing pigs without antibiotics on NH 3 emissions from a swine experimental building starting with 657 piglets during a wean-to-finish production cycle of 154 days. Pigs were reared in two groups of 10 rooms that were divided into five 2-room pairs (P1–P5) and fed in nine dietary phases. Each pair consisted of one room without antibiotics (no antibiotics in the diet, water, or injectable) and another room as a positive control. Control animals were fed diets containing carbadox-10 (phases 1–4), chlortetracycline (CTC, phase 5), lincomix (phases 6–7), and tylan 40 (phases 8–9). Temperatures in the pig living space and the under-floor manure pit headspace were continuously measured. Ventilation rates at all wall fans and pit fans were obtained by continuous monitoring. Ammonia concentrations in the wall and pit fan exhaust air, and in room inlet air were measured with two multi-gas monitors. Only days that contained at least 18 h of data each day were validated and used. The study generated 1337 room-days of valid data of NH 3 emission rates, with a data completeness of 88.6%. Daily mean NH 3 emission patterns demonstrated large variations between the paired rooms and among different pairs. Within the individual 2-room pairs, no NH 3 emission differences were found in P1 (rooms 1 and 2, p = 0.34) and P2 (rooms 3 and 4, p = 0.44). Significant differences were found in P3–P5 (p < 0.01). The antibiotic-free rooms emitted more NH 3 from P3 and P4, but less NH 3 from P5. However, the combined cycle mean NH 3 emissions from the group of five antibiotic-free rooms and the group of five control rooms were 41.6 ± 10.5 and 39.4 ± 10.6 g d−1 AU−1 (mean ± standard deviation. AU = 500 kg live body weight), respectively. Therefore, there was no statistical difference in combined cycle mean NH 3 emissions from rearing pigs with or without antibiotics (p = 0.78). This study also revealed that experiments with multiple replicates and long NH 3 monitoring durations were necessary to avoid potential misinterpretation of experimental results. Unlabelled Image • Ammonia emissions from 10 swine rooms (5 pairs) were studied for 154 days. • Different pairs showed different effects of antibiotics on ammonia emissions. • Overall, antibiotic-free pig rearing did not increase ammonia emissions (p = 0.78). • Multi-replicate and long-monitoring studies could avoid result misinterpretation. [ABSTRACT FROM AUTHOR]

• A workflow to construct solid-molten salt interaction potential is designed. • Deep potential could yield accurate solid-molten salt interaction at ab initio level. • Trends in interfacial heat transfer are correctly described by deep potential model. Interfacial heat and mass transfer properties at molten salt/solid interfaces are crucial for the study of heat storage/transfer properties of molten salt nanocomposite materials as well as the microscopic mechanism of thermophysical property enhancement, but accurate force field parameters for describing molten salt-solid interactions are still lacking. This study has utilized a workflow that could meet the demand of high accuracy and efficiency in molecular dynamics (MD) simulations of molten salt/solid interface with the deep potentials (DPs) trained by deep learning (DL), using SiO 2 /LiCl-KCl interface as a model system. In terms of the short-ranged polarizability and long-ranged correlations of ions, DPs can give accurate description of potential energy surface over wide temperature range at the level of ab initio calculations. Further analysis on interfacial thermal resistance (ITR) and thermal conductivity shows that the slowing down of heat transfer is related to the disordered microstructure of molten salt ions near the SiO 2 surfaces, which also leads to larger ITR. For the mass transfer of molten salt ions on the SiO 2 surfaces, the more active ionic diffusion and permeation through the solid can be observed due to the weaker adsorption between them, which is ascribed primarily to the high temperature. The workflow, of which the feasibility has been verified for molten salt/solid interfaces in this work with rigorous modeling, will be used for building accurate interatomic interaction models and calculating thermophysical properties for various complex interfacial systems containing molten salts. The influence of interfacial microstructure on heat and mass transfer will provide theoretical support for the application of molten salts in energy industry. [ABSTRACT FROM AUTHOR]

• Enrichment of molten salt ions at interface contributes to enhanced heat transfer. • Interfacial thermal resistances are correlated with layering of interfacial ions. • Continuum model with interfacial effect yield good prediction of thermal transport. The solid-liquid interface between molten salt and solid oxides is ubiquitous in the molten salt nanocomposite with enhanced heat storage and transfer properties for concentrating solar power (CSP) systems. Understanding the microscopic mechanisms of interfacial thermal transport on this solid-liquid interface have great significance for evaluating the effective thermal properties of nanocomposites. This study combines equilibrium and non-equilibrium molecular dynamics simulations to explore the thermal transport and its connection with interfacial microstructure at the solid MgO-molten Hitec salt interface. Simulation results indicate that the enhancement of thermal transport can be ascribed primarily to the highly ordered adsorption structure of molten salt ions formed at the MgO surface, and the effect medium model incorporated with the simulated interfacial thermal resistance can reproduce the thermal conductivity of nanocomposite accurately. Further investigation indicates that the stronger adsorption at the MgO (110) surface leads to smaller interfacial thermal resistance than the MgO (100) surface, while the heat transfer parallel to the slab does not show much difference in both surfaces. These findings have illustrated the enrichment of molten salt ions at the solid surface does have a strong enhancement effect on their heat transfer properties and it is also necessary to incorporate the contribution from this interfacial thermal transport enhancement when predicting the thermophysical properties of molten salt nanocomposite materials. [Display omitted] [ABSTRACT FROM AUTHOR]

Molten chloride salt is recognized as a promising heat transfer and storage medium in concentrating solar power (CSP) in recent years, but there is a serious lack for thermal property data of molten chloride salts under high-temperature condition. In this work, temperature and component dependence of local structure and physical properties for binary KCl–MgCl 2 mixture were computed by molecular dynamics simulations (MD) method based on Born–Mayer–Huggins (BMH) potential. As the temperature rises, the distances between ions change and the structures turn into loose state, thus the density, thermal conductivity and the shear viscosity decrease, which also agree well with the experimental results. The calculation errors of thermal properties are mainly within 8%. The results show that density and thermal conductivity have negative linear correlation with temperature. Specific heat capacity is invariant with temperature at a constant pressure. When K+ increases in the salt, thermal conductivity is significantly improved, and shear viscosity and specific heat capacity decrease. The formulas of temperature-thermal properties-component correlations are obtained, which provide the fundamental property database for the precise design of high-temperature thermal storage system. ● Structures and thermal properties of KCl–MgCl 2 were calculated by MD simulations. ● Properties of KCl–MgCl 2 were influenced by component and temperature. ● With increasing K+, coordination structures became looser and densities decreased. ● The correlations of properties and component/temperature were obtained. [ABSTRACT FROM AUTHOR]

NaCl–CaCl 2 –MgCl 2 ternary molten salt is a potential material for thermal transfer and storage applications at high temperatures. In the present work, its microstructures and thermophysical properties over a wide operating temperature range were investigated by using ab-initio molecular dynamics simulations. An approach-to-equilibrium molecular dynamics method was used to calculate the thermal conductivity of molten salts. The local coordination structures and mechanisms of their temperature dependence were investigated. It can be found that the dominant bonding interactions are between cation-chlorine ion pairs, which can be considered as bridges connecting the local structures in liquids. The interaction between ions decreases with the increase of temperature as distances of ion clusters get larger. The thermophysical properties were evaluated in detail from 703 to 1173 K, showing a good accordance with the experimental data. A detailed relationship between operating temperature, microstructure, and thermophysical properties has been studied. The results suggest that the changes in thermodynamic properties with increasing temperature are caused by the variations of microstructures, in terms of the distances and bonding characteristics of ions. • Ab-initio molecular dynamics simulations are applied for NaCl–CaCl 2 –MgCl 2. • A pproach-to-equilibrium molecular dynamics method is used for thermal conductivity. • The relationship between operating temperature and properties has been studied. • Properties of molten salt are determined by the distances and interactions of ions. [ABSTRACT FROM AUTHOR]