Outflow Temperature Research Articles

Balanced 20-kA DC Distributor for Magnetized Taylor Couette Systems, Utilizing Thermostatic Controlled Water Valves With CO2Adsorption Charge Sensors as Current Controller

A quasi-coaxial system consisting of a central current carrying copper rod and five symmetric return paths takes up to 20 kA. The installation provides a homogeneous magnetic field $\mathbf {B_{\varphi }}$ to a Taylor–Couette flow. One challenging part of the system is the design of the current distributor, which is supposed to divide the return current into several equally weighted lines. The individual components like the copper rods as well as all electrical contacts provide a characteristic resistance, each in the same magnitude of several $ {\mu }\Omega $ . By initial installation this will support an imbalance in the current distribution affecting the symmetry of the magnetic field. So the adjustment of current distribution becomes mandatory to ensure maximum field homogeneity. Controlling the outflow temperature of the required water cooling offers an indirect access to set the current by thermostatically operated valves with CO2 adsorption charge in conjunction with the temperature dependent branch resistance. A numerical investigation proves that a stable current distribution can be achieved by a couple of paralleled thermal controlled heater valves with proportional characteristics. Finally, recent ironless Hall-effect current sensors help to calibrate the system so that the current homogeneity differs less than 1% from optimal state in a wide range of currents.

The near-infrared outflow and cavity of the proto-brown dwarf candidate ISO-Oph 200

In this Letter a near-infrared integral field study of a proto-brown dwarf candidate is presented. A ~0.′′5 blue-shifted outflow is detected in both H2 and [Fe II] lines at Vsys = (–35 ± 2) km s−1 and Vsys = (–51 ± 5) km s−1 respectively. In addition, slower (~±10 km s−1) H2 emission is detected out to <5.′′4, in the direction of both the blue and red-shifted outflow lobes but along a different position angle to the more compact faster emission. It is argued that the more compact emission is a jet and the extended H2 emission is tracing a cavity. The source extinction is estimated at Av = 18 ± 1 mag and the outflow extinction at Av = 9 ± 0.4 mag. The H2 outflow temperature is calculated to be 1422 ± 255 K and the electron density of the [Fe II] outflow is measured at ~10 000 cm−3. Furthermore, the mass outflow rate is estimated at Ṁout [H2] = 3.8 × 10−10 M⊙ yr−1 and Ṁout[Fe II] = 1 × 10−8 M⊙ yr−1. Ṁout[Fe II] takes a Fe depletion of ~88% into account. The depletion is investigated using the ratio of the [Fe II] 1.257 μm and [P II] 1.188 μm lines. Using the Paβ and Brγ lines and a range in stellar mass and radius Ṁacc is calculated to be (3–10) × 10−8 M⊙ yr−1. Comparing these rates puts the jet efficiency in line with predictions of magneto-centrifugal models of jet launching in low mass protostars. This is a further case of a brown dwarf outflow exhibiting analogous properties to protostellar jets.

Analysis of the Thrust Force on the Temperature-Control Curtain in a Large Stratified Reservoir

AbstractA temperature-control curtain (TCC) is an effective facility to regulate the outflow temperature in reservoirs, and its safety and stability are of great concern. The pressure difference be...

Effects of dam reconstruction on thermal-ice regime of Fengman Reservoir

A laterally-averaged 2D water temperature model coupled with an ice cover module was used to investigate the influences of the Fengman Dam reconstruction on its thermal regime. Variations of the thermal-ice regime and outflow temperature under typical hydro-metrological conditions were simulated and validated with field data. Due to the partial dismantling of the old dam after the reconstruction, the intake water is primarily taken from the surface layer of the reservoir. As a result, the total heat storage of the reservoir throughout the year and the outflow temperature from January to March will decrease. Furthermore, the low outflow temperature in the winter will result in a decline of the downstream water temperature and negatively impact the rime scenery near Jilin City. In order to increase the outflow temperature in winter, an operation scheme that combined the new intake with the old intake of the III-phase project of old dam was discussed. The results indicated that this scheme could increase the outflow temperature to ensure a 70km open channel in the downstream river in a typical winter, and eliminated the negative effects on the rime scenery.

Understanding the Temperature Variations and Thermal Structure of a Subtropical Deep River-Run Reservoir before and after Impoundment

A two-dimensional hydrodynamic CE-QUAL-W2 model was configured for a deep subtropical river-run reservoir, the Xiluodu Reservoir (XLDR), in China to simulate water temperature in the first two years of impoundment (2013–2014) using measured data as model input. It was calibrated using observed temperature profiles near the dam and the outflow temperatures. Observed daily temperatures at four gauging stations upstream or downstream of XLDR before (2000–2012) and after the impoundment (4 May 2013) were analyzed and fitted with a sine function representing seasonal temperature variation. The fitted annual temperature phase shifts showed no phase delay in XLDR area before the impoundment but revealed a phase delay about 17 days between outflow and inflow after the impoundment, which was not caused by the air temperature variation. The simulated temperatures verified a similar phase delay after the impoundment. The simulated temperatures, water ages, and vertical temperature gradients demonstrated an average metalimnetic deepening rate of 0.49 m/day (average inflow ~4500 m3/s) while the largest rate due to massive inflow (~15,000 m3/s) was 1.67 m/day. The W2 model was run under hypothetic scenarios of different inflow/outflow rates and outflow withdrawn elevations. The results revealed that greater inflow/outflow rate could lead to higher metalimnetic deepening rate and smaller outflow phase delay, while deeper outflow withdrawn could lead to deeper metalimnion and larger epilimnetic depth.

On the Seasonal Cycles of Tropical Cyclone Potential Intensity

Recent studies have investigated trends and interannual variability in the potential intensity (PI) of tropical cyclones (TCs), but relatively few have examined TC PI seasonality or its controlling factors. Potential intensity is a function of environmental conditions that influence thermodynamic atmosphere–ocean disequilibrium and the TC thermodynamic efficiency—primarily sea surface temperatures and the TC outflow temperatures—and therefore varies spatially across ocean basins with different ambient conditions. This study analyzes the seasonal cycles of TC PI in each main development region using reanalysis data from 1980 to 2013. TC outflow in the western North Pacific (WNP) region is found above the tropopause throughout the seasonal cycle. Consequently, WNP TC PI is strongly influenced by the seasonal cycle of lower-stratospheric temperatures, which act to damp its seasonal variability and thereby permit powerful TCs any time during the year. In contrast, the other main development regions (such as the North Atlantic) exhibit outflow levels in the troposphere through much of the year, except during their peak seasons. Mathematical decomposition of the TC PI metric shows that outflow temperatures damp WNP TC PI seasonality through thermodynamic efficiency by a quarter to a third, whereas disequilibrium between SSTs and the troposphere drives 72%–85% of the seasonal amplitude in the other ocean basins. Strong linkages between disequilibrium and TC PI seasonality in these basins result in thermodynamic support for powerful TCs only during their peak seasons. Decomposition also shows that the stratospheric influence on outflow temperatures in the WNP delays the peak month of TC PI by a month.

Modeling the effect of temperature-control curtain on the thermal structure in a deep stratified reservoir

Temperature-control curtain (TCC) is an effective facility of selective withdrawal. Previous research has estimated the influence of TCC on the outflow temperature, but its effect on the thermal structure of a reservoir area is unknown, which is crucial to the reservoir ecology. For this purpose, taking the Sanbanxi Reservoir as a case study, a 2-D hydrodynamic and temperature model covering the whole reservoir was built and calibrated to simulate the flow and temperature fields under different TCC scenarios, and the change rules of thermal stability and outflow temperature are obtained. When the water-retaining proportion (Pr) of bottom-TCC increases, the temperature difference between inflow and outflow monotonously decreases, while the thermal stability first increases and later decreases. The maximum thermal stability exists at Pr = 62.5%; it goes against water quality improvement and should be avoided in practice. A bottom-TCC with Pr > 80% is practical for deep reservoirs such as Sanbanxi Reservoir to decrease the temperature difference between inflow and outflow without the increase of thermal stability. In terms of top-TCC, as Pr increases, the temperature difference between inflow and outflow monotonously increases and thermal stability decreases. The top-TCCs are recommended when a smaller thermal stability is more preferentially considered than outflow temperature, or a cool outflow in the summer is required for downstream coldwater fishes. In addition, the TCC cannot decrease or increase the outflow temperature all of the time throughout the whole year, and it primarily changes the phase and variation range of the outflow temperature. This study quantitatively estimates the potential effect of TCCs on the thermal structure and water environment management and provides a theoretical basis for the application of TCC.

Microbial Composition and Diversity Patterns in Deep Hyperthermal Aquifers from the Western Plain of Romania.

A limited number of studies have investigated the biodiversity in deep continental hyperthermal aquifers and its influencing factors. Here, we present the first description of microbial communities inhabiting the Pannonian and Triassic hyperthermal aquifers from the Western Plain of Romania, the first one being considered a deposit of "fossilized waters," while the latter is embedded in the hydrological cycle due to natural refilling. The 11 investigated drillings have an open interval between 952 and 3432m below the surface, with collected water temperatures ranging between 47 and 104°C, these being the first microbial communities characterized in deep continental water deposits with outflow temperatures exceeding 80°C. The abundances of bacterial 16S rRNA genes varied from approximately 105-106mL-1 in the Pannonian to about 102-104mL-1 in the Triassic aquifer. A 16S rRNA gene metabarcoding analysis revealed distinct microbial communities in the two water deposits, especially in the rare taxa composition. The Pannonian aquifer was dominated by the bacterial genera Hydrogenophilus and Thermodesulfobacterium, together with archaeal methanogens from the Methanosaeta and Methanothermobacter groups. Firmicutes was prevalent in the Triassic deposit with a large number of OTUs affiliated to Thermoanaerobacteriaceae, Thermacetogenium, and Desulfotomaculum. Species richness, evenness, and phylogenetic diversity increased alongside with the abundance of mesophiles, their presence in the Triassic aquifer being most probably caused by the refilling with large quantities of meteoric water in the Carpathian Mountains. Altogether, our results show that the particular physico-cheminal characteristics of each aquifer, together with the water refilling possibilities, seem to determine the microbial community structure.

Large‐scale control of the lower stratosphere on variability of tropical cyclone intensity

Recent studies of tropical cyclones (TC) have suggested intricate impacts of the lower stratosphere layer (LSL) on TC development at the high-intensity limit. This study examines the potential realization of the impacts of the LSL interannual variability on TC intensity. By minimizing the effects of sea surface temperature and outflow temperature based on the potential intensity framework, partial correlation analyses show a negative correlation between the power dissipation index (PDI) for intense TCs and the tropopause height in the northwestern Pacific basin, but a weaker relationship in the north Atlantic basin. Similar analyses for the LSL stratification also reveals signals of negative correlations between the LSL stratification and PDI in both basins, corroborating recent modeling studies about the impacts of the LSL on TC development. Due to the complexity of the relationships and data limitations, however, all correlations are statistically insignificant, thus rendering the impacts of LSL on TC intensity inconclusive at present.

Upgrading sensible-heat storage with a thermochemical storage section operated at variable pressure: An effective way toward active control of the heat-transfer fluid outflow temperature

This article introduces a novel thermal-energy storage concept that allows the outflow temperature of the heat-transfer fluid to be controlled during discharging. The concept is based on placing a thermochemical-storage section on top of a sensible thermal-energy storage section. The thermochemical-storage section comprises tubes that house gaseous and solid reactants undergoing reversible endo/exothermic cycling. Because the reactants are physically separated from the heat-transfer fluid, the reaction pressure can be independently adjusted using a compressor. As a result, the equilibrium reaction temperature can be tuned to reach the rate and temperature of the exothermic reaction that allow the heat-transfer fluid passing the tubes to be heated to a desired temperature during discharging. Transient simulations of such a combined sensible/thermochemical thermal-energy storage confirm that during discharging the heat-transfer fluid can be heated to a constant outflow temperature that is equal to or higher than the inflow temperature during charging. The calculated cycle efficiency of the combined storage accounts for the parasitic losses introduced by the reaction pressure swing and is compared to the cycle efficiency of a sensible storage operating under equal inflow conditions.

Tropical Cyclone Outflow and Warm Core Structure as Revealed by HS3 Dropsonde Data

Abstract Dropsonde data collected during the NASA Hurricane and Severe Storm Sentinel (HS3) field campaign from 16 research missions spanning 6 tropical cyclones (TCs) are investigated, with an emphasis on TC outflow and the warm core. The Global Hawk (GH) AV-6 aircraft provided a unique opportunity to investigate the outflow characteristics due to a combination of 18+-h flight durations and the ability to release dropsondes from high altitudes above 100 hPa. Intensifying TCs are found to be associated with stronger upper-level divergence and radial outflow relative to nonintensifying TCs in the sample, regardless of current intensity. A layer of 2–4 m s−1 inflow 20–50 hPa deep is also observed 50–100 hPa above the maximum outflow layer, which appears to be associated with lower-stratospheric descent above the eye. The potential temperature of the outflow is found to be more strongly correlated with the equivalent potential temperature of the boundary layer inflow than to the present storm intensity, consistent with the outflow temperature having a stronger relationship with potential intensity than actual intensity. Finally, the outflow originates from a region of low inertial stability that extends above the cyclone from 300 to 150 hPa and from 50- to 200-km radius. The unique nature of this dataset allows the height and structure of the warm core also to be investigated. The magnitude of the warm core was found to be positively correlated with TC intensity, while the height of the warm core was weakly positively correlated with intensity. Finally, neither the height nor magnitude of the warm core exhibits any meaningful relationship with intensity change.

Design of high-pressure direct contact heater for promising power supply units: Experimental substantiation

The results of experimental studies of superheated steam condensation on feed water jets in a highpressure, direct-contact heat exchanger are presented. Direct contact feed water heater (DCFWH) can be used in a dual-flow diagram of a steam-power unit with ultrasupercritical steam parameters (35 MPa, 700/720°C). The direct contact feed water heater is included in the flow diagram of the II circuit in a promising power unit; it provides feed water heating to 340°C in all maintenance and emergency operation modes of the unit. The reliability of the high-pressure direct contact heater operation in this flow diagram is of major importance in relation to the danger of lead solidification in the tube space of the steam generator. Technical requirements to the design of the high-pressure direct contact heater for increasing the heat exchange efficiency are formulated based on the results of earlier studies with steam–water mixture as the heating medium. The results of studies of superheated steam condensation on jets presented in this study testify that feed water is additionally heated to the required temperature at the output of the installation. The influence of initial feed water parameters (outflow velocity and temperature) on the jet heating length is elucidated. The numerical approximation of the experimental data for determination of the jet heating length in the nominal and partial power unit loads is obtained. The results of the calculations are used to simplify the design of the water-supplying element for the direct contact feed water heater. The proposed design of direct contact feed water heater is characterized by simplicity and low metal intensity, which provides the installation reliability at the considered pressure level due to the minimum number of structural elements.

Deep hydrothermal fluid–rock interaction: the thermal springs of Da Qaidam, China

AbstractHot water flows from springs along the border fault system at the SW rim of the Qilian Mountains near the city of Da Qaidam (Qinghai Province, Western China). The outflow temperature is close to 72°C, and the clear water contains about 1.4 g l−1 total dissolved solids. The water contains predominantly Na and Cl, and significant and equal amounts of hydrogen carbonate and sulfate. The water originates from a fractured granite reservoir at about 5 km depth, suggested by the estimated Qtz and Na–K equilibrium temperatures of 130–150°C. The solutes are derived from the interaction of the deep ground water with the solids of the fractured granite. However, the high Cl/Br mass ratio of about 550 in the deep water and the composition of surface runoff suggest the presence of an additional evaporite component introduced by surface infiltration. The source of this surface component is probably eolian deposits of halite, gypsum, and borate minerals from the salt flats and deserts of the Qaidam Basin on the slopes of the Qilian Mountains. The deep hydrothermal flow system is topography driven, and the upwelling water is focused and channeled to the damage zone of the Qilian border fault.

Small reservoir effects on headwater water quality in the rural-urban fringe, Georgia Piedmont, USA

Abstract Small reservoirs are prevalent landscape features that affect the physical, chemical, and biological characteristics of headwater streams. Tens of thousands of small reservoirs, often less than a hectare in size, were constructed over the past century within the United States. While remote-sensing and geographic-mapping technologies assist in identifying and quantifying these features, their localized influence on water quality is uncertain. We report a year-long physicochemical study of nine small reservoirs (0.15–2.17 ha) within the Oconee and Broad River Watersheds in the Georgia Piedmont. Study sites were selected along an urban-rural gradient with differing amounts of agricultural, forested, and developed land covers. Sites were sampled monthly for discharge and inflow/outflow water quality parameters (temperature, specific conductance, pH, dissolved oxygen, turbidity, alkalinity, total phosphorus, total nitrogen, nitrate, ammonium). While the proportion of developed land cover within watersheds had positive correlations with reservoir specific conductivity values, agricultural and forested land covers showed correlations (positive and negative, respectively) with reservoir alkalinity, total nitrogen, nitrate, and specific conductivity. The majority of outflow temperatures were warmer than inflows for all land uses throughout the year, especially in the summer. Outflows had lower nitrate concentrations, but higher ammonium. The type of outflow structure was also influential; top-release dams showed higher dissolved oxygen and pH than bottom-release dams. Water quality effects were still evident 250 m below the dam, albeit reduced.

A Reformulation of Tropical Cyclone Potential Intensity Theory Incorporating Energy Production along a Radial Trajectory

AbstractA modified formula for calculating tropical cyclone (TC) potential intensity (PI) from a balance between energy production and frictional dissipation in the TC surface layer is developed. This modified formula accounts for energy production and frictional dissipation at multiple radii (and therefore at multiple wind speeds) along the TC inflow trajectory. The PI maximum wind speed values VMAX are calculated using this expanded formula for four canonical radial profiles of wind speed. These results are compared to PI VMAX values calculated using the standard assumption that all energy production and frictional dissipation relevant to maximum intensity occurs at the radius of maximum winds (RMW).The new PI formulation developed here results in PI VMAX values substantially higher than the standard PI VMAX for all four of the radial wind speed profiles examined; the difference is explained by the increase in the outer radial limit of energy production. This increase holds true even if outflow temperature increases with increasing radius, although the VMAX increases with increasing outer radius are somewhat more modest in this case. The extended PI formula yields VMAX values 3–17 m s−1 higher than the standard PI VMAX value when calculated with outer energy production–dissipation limits of 2.0–2.5 RMW, although it yields potentially unrealistic values when calculated with larger outer limits (e.g., 6 RMW). These results are presented as a potential explanation for why individual TCs can exceed their standard PI VMAX values in terms of the storm thermodynamics.

Usefulness of thermographic analysis to control temperature homogeneity in the development and implementation of a closed recirculating CO2 chemohyperthermia model

Purpose: To determine the effectiveness of thermography to control the distribution of abdominal temperature in the development of a closed chemohyperthermia model.Materials and methods: For thermographic analysis, we divided the abdominopelvic cavity into nine regions according to a modification of carcinomatosis peritoneal index. A difference of 2.5 °C between and within the quadrants, and thermographic colours, were used as asymmetric criteria. Preclinical study:· Rats Model: Six athymic nude rats, male, rnu/rnu. They were treated with closed technique and open technique. Porcine Model: 12 female large white pigs. Four were treated with open technique and eight with closed recirculation CO2 technique. Clinical Pilot Study, EUDRACT 2011-006319-69: 18 patients with ovarian cancer were treated with cytoreductive surgery and hyperthermia intraperitoneal chemotherapy, HIPEC, with a closed recirculating CO2 system. Thermographic control and intra-abdominal temperature assessment was performed at the baseline, when outflow temperature reached 41 °C, and at 30´.Results: The thermographic images showed a higher homogeneity of the intra-abdominal temperature in the closed model respect to the open technique. The thermogram showed a temperature distribution homogeneity when starting the circulation of chemotherapy. There was correlation between the temperature thermographic map in the closed porcine model and pilot study, and reached inflow and outflow temperatures, at half time of HIPEC, of 42/41.4 °C and 42 ± 0.2/41 ± 0.8 °C, respectively. There was no significant impact to the core temperature of patients after reaching the homogeneous temperature distribution.Conclusions: To control homogeneity of temperature distribution is feasible using infra-red digital images in a closed HIPEC with CO2 recirculation.

Comparison of the Tornadic and Nontornadic Supercells Intercepted by VORTEX2 on 10 June 2010

On 10 June 2010, the second Verification of the Origins of Rotation in Tornadoes Experiment (VORTEX2) armada collected a rare set of observations of a nontornadic and a tornadic supercell evolving in close proximity to each other. The storms and their environments were analyzed using single- and dual-Doppler radar, mobile mesonet, deployable surface mesonet, and mobile sounding data, with the goal of understanding why one supercell produced no tornadoes while the other produced at least two. Outflow temperature deficits were similar for the two storms, both within the normal range for weakly tornadic supercells but somewhat cold relative to significantly tornadic supercells. The storms formed in a complex environment, with slightly higher storm-relative helicity near the tornadic supercell. The environment evolved significantly in time, with large thermodynamic changes and increases in storm-relative helicity, leading to conditions much more favorable for tornadogenesis. After a few hours, a new storm developed between the supercells, likely leading to the demise of the nontornadic supercell before it was able to experience the enhanced environmental conditions. Two tornadoes developed within the single mesocyclone of the other supercell. After the dissipation of the second tornado, rapid rearward motion of low- to midlevel circulations may have inhibited further tornado production in this storm.

Numerical simulation of a high-temperature aquifer thermal energy storage system coupled with heating and cooling of a thermal plant in a cold region, China

This study investigates the performance of an aquifer thermal energy storage system (ATES) that is coupled with the cooling tower of a seasonally-running thermal plant. The ATES supplies cool water and stores heated water for the cooling tower during the runtimes of the thermal plant. Moreover, it supplies warm water for bathing or irrigation during downtimes of the thermal plant. The performance of ATES is evaluated numerically for a full year, and well placement is optimized. Findings indicate that the ATES system could be optimized by locating the cool water supply well upstream of the storage well. In the optimized ATES, the outflow temperature from the cool water supply well can be maintained below 15 °C, which satisfies the temperature requirement for the cooling tower. The injection of heated water (with temperature of 70 °C) at 8400 m3/d for six months leads to over 140,000 m3 of warm water (with temperature ≥ 40 °C) stored in the aquifer. This warm water can supply at least 12,000 m3/d of warm water for six months. The recovery efficiency is estimated at 60.9%, and the energy loss is attributed to rainfall infiltration, thermal diffusion into underlying low-permeability layer and advection downstream.

A simple model of gravitationally-driven water flow in a semicircular aquifer to estimate geothermal power potential: Examples from Arizona and Colorado

An analytical model has been developed from which the basic thermal parameters of the flow through non-magmatic hot-spring systems can be calculated from data that can be obtained at their discharge: water outflow temperature, mean surface temperature, and water geochemistry. From this flow, the maximum thermal power potential of a system can be calculated. The model has been applied to Clifton Hot Springs in eastern Arizona, USA, and the potential power generation of this system was estimated to be within the range of 0.8–3 MW. The model has also been successfully applied to three hot spring systems in Colorado with different characteristics. The simple model is not thought to represent the details of flow in the aquifers, but provides a useful approximation of the temperatures and thermal power potential in the systems.

Evaluación inicial de parámetros de campo en un biodigestor anaeróbico para el tratamiento de aguas residuales

<p>El biodigestor anaerobio utilizado en este estudio, se diseñó para tratar agua residual doméstica en un sanitario de prueba, que se caracteriza por ser de: flujo continuo, baja carga orgánica y tener cuatro etapas de proceso. La importancia del prototipo estudiado radicó en las condiciones reales en que se probó. La primera etapa consistió en la selección del sitio, construcción del prototipo en ferrocemento con capacidad de 1m, impermeabilización y carga. En esta etapa se inoculó el reactor con materia orgánica procedente de las descargas del sanitario, durante el periodo de agosto a diciembre de 2011. La evaluación de este periodo consistió en la medición de parámetros de campo: pH, conductividad eléctrica, sólidos sedimentables, temperatura del influente y efluente del sistema que permitieron verificar el comportamiento del proceso del digestor durante la fase de arranque. Los resultados obtenidos para estas determinaciones a la entrada y salida del biodigestor respectivamente son los siguientes: pH (8.03; 8.43), conductividad eléctrica (1510.83 µS/cm; 1207.00 µS/cm), temperatura del proceso (19.2°C; 20.1°C), sólidos sedimentables (144.5mL/L; 0.02mL/L), oxígeno disuelto (4.5992 mg/L; 0.1924 mg/L) estos datos proporcionaron un punto de partida para el tratamiento de aguas residuales de tipo doméstica.</p>