Specific Temperature Profiles Research Articles

What can go wrong in a dividing wall column and how to detect it

Dividing wall columns are state of the art distillation arrangements performing three separation tasks within one unit. Compared to using two conventional columns in series this saves both capital costs and energy but on the other hand it brings a higher risk of malfunction. This simulation study analyses what can go wrong during the operation of dividing wall columns. The emphasis is on the operation of the prefractionator section, that is, on the choice on the liquid and vapor splits, which is crucial for the overall performance. The resulting two-way flows between the prefractionator and main column gives a broader feasible operating range than in a conventional column arrangement. This can lead to peculiar behavior, including circulation of components around the dividing wall. This paper identifies 15 non-optimal operating regions for the prefractionator with specific internal flow patterns, characteristic temperature and composition profiles for the separation of a fairly ideal mixture of benzene, toluene and p-xylene. From these results it is possible to identify and hopefully rectify wrong choices for the liquid and vapor splits in a dividing wall column.

Joint Use of Far‐Infrared and Mid‐Infrared Observation for Sounding Retrievals: Learning From the Past for Upcoming Far‐Infrared Missions

AbstractAtmosphere and surface properties are routinely retrieved from satellite measurements and extensively used in weather forecast and climate analysis. Satellite missions dedicated to fill the gap of far‐infrared (far‐IR) observations are scheduled to be launched this decade. To explore mid‐infrared (mid‐IR) and far‐IR joint retrievals for the future far‐IR satellite missions, this study uses an optimal‐estimation‐based method to retrieve atmospheric specific humidity and temperature profiles, surface skin temperature, and surface spectral emissivity from the Infrared Interferometer Sounder‐D (IRIS‐D) measurements in 1970, the only existing spaceborne far‐IR spectral observations with global coverage. Based on a set of criteria, two cases in the Arctic, which are most likely under clear‐sky conditions, are chosen for the retrieval experiments. Information content analysis suggests that the retrieved surface skin temperature and the mid‐IR surface spectral emissivity are highly sensitive to the true values while the retrieval estimates of far‐IR surface emissivity are subject to the variation of water vapor abundance. Results show that radiances based on the retrieved state variables are more consistent with the IRIS‐D observations compared to those based on the reanalysis data. Retrieval estimates of the state variables along with retrieval uncertainties generally fall within reasonable ranges. The relative uncertainties of retrieved state variables decrease compared to the a priori relative uncertainties. In addition, the necessity to retrieve surface emissivity is corroborated by a parallel retrieval experiment assuming a blackbody surface emissivity that has revealed significant distortions of retrieved specific humidity and temperature profiles in the Arctic lower troposphere.

Stress during first gestation of ewes impairs memory and learning of male offspring.

This study aimed to investigate the influence of gestational stress induced by lipopolysaccharide (LPS, Escherichia coli) on the physiological changes of ewes, as well as on the subsequent behavioral interaction between ewes and lambs and on the memory and learning of 30-day-old offspring in a T-maze. Thirty-six nulliparous pregnant crossbred Santa Ines ewes with an initial live weight of 45 ± 6kg, age of 12 ± 2months, and body condition score between 3 and 3.5 (on a scale of 1 to 5) were divided into two treatments: LPS treatment (E. coli; 0.8μg.kg-1) and Control (placebo/saline) administered in late pregnancy (day 120). Blood samples were collected before (0h at 5:00h) and 1h, 2h, 4h, 8h, 12h, 24h after the administration of LPS or placebo to determine the cortisol release curve. Rectal temperature was measured at the same time points. After birth, male lambs (N = 19) were used to evaluate the maternal-offspring behavioral interaction, weight, and cognitive ability in a T-maze. Blood cortisol and rectal temperature of ewes increased after LPS administration and returned to baseline levels after 24h. The activities facilitating and stimulating suckling were higher on LPS group (P < 0.05). Lambs whose mothers were challenged with LPS during late pregnancy showed greater learning and memory disabilities including fear behavior and the inability to make decisions at 30days of age in the T-maze. In sheep, the immunological stress induced by LPS in late pregnancy promotes an inflammatory response characterized by specific rectal temperature and cortisol release profiles, improving maternal care that can increase offspring survival; however, the exposure of sheep fetuses to maternal inflammation causes cognitive impairment in lambs at 30days of age, which could not be reduced by the behavioral interaction between the mother and offspring.

A design concept of active cooling for tailored forming workpieces during induction heating

The demand for lightweight construction is constantly increasing. One approach to meet this challenge is the development of hybrid components made of dissimilar materials. The use of the hybrid construction method for bulk components has a high potential for weight reduction and increased functionality. However, forming workpieces consisting of dissimilar materials requires specific temperature profiles for achieving sufficient formability. This paper deals with the development of a specific heating and cooling strategy to generate an inhomogeneous temperature distribution in hybrid workpieces. Firstly, the heating process boundaries with regard to temperature parameters required for a successful forming are experimentally defined. Secondly, a design based on the obtained cooling strategy is developed. Next a modelling embedded within an electro-thermal framework provides the basis for a numerical determination of admissible cooling rates to fulfil the temperature constraint. Here, the authors illustrate an algorithmic approach for the optimisation of cooling parameters towards an effective minimum, required for applicable forming processes of tailored forming.

Non-coaxial-based microwave ablation antennas for creating symmetric and asymmetric coagulation zones

We present an investigation of a new class of microwave ablation (MWA) antennas capable of producing axially symmetric or asymmetric heating patterns. The antenna design is based on a dipole fed by a balanced parallel-wire transmission line. The angle and direction of the deployed dipole arms are used to control the heating pattern. We analyzed the specific absorption rate and temperature profiles using electromagnetic and thermal simulations. Two prototypes were fabricated and tested in ex vivo ablation experiments: one was designed to produce symmetric heating patterns and the other was designed to generate asymmetric heating patterns. Both fabricated prototypes exhibited good impedance matching and produced localized coagulation zones as predicted by the simulations. The prototype operating in porcine muscle created an ∼10 cm3 symmetric ablation zone after 10 min of ablation with a power level of 18 W. The prototype operating in egg white created an ∼4 cm3 asymmetric ablation zone with a directionality ratio of 40% after 5 min of ablation with a power level of 25 W. The proposed MWA antenna design shows promise for minimally invasive treatment of tumors in various clinical scenarios where, depending on the situation, a symmetric or an asymmetric heating pattern may be needed.

Industrial excess heat for district heating in Denmark

Excess heat is available from various sources and its utilisation could reduce the primary energy use. The accessibility of this heat is however dependent amongst others on the source and sink temperature, amount and potential users in its vicinity. In this work a new method is developed which analyses excess heat sources from the industrial sector and how they could be used for district heating. This method first allocates excess heat to single production units by introducing and validating a new approach. Spatial analysis of the heat sources and consumers are then performed to evaluate the potential for using them for district heating. In this way the theoretical potential of using the excess heat for covering the heating demand of buildings is determined. Through the use of industry specific temperature profiles the heat usable directly or via heat pumps is further found. A sensitivity analysis investigates the impact of future energy efficiency measures in the industry, buildings and the district heating grid on the national potential. The results show that for the case study of Denmark, 1.36TWh of district heat could be provided annually with industrial excess heat from thermal processes which equals 5.1% of the current demand. More than half of this heat was found to be usable directly, without the need for a heat pump.

Performance Comparison Among Gas Heat Pump, Electric Heat Pump and Conventional Thermal Devices in Tertiary Sector Applications

Efficiency in thermal power production is supported by the continuous development of new technologies for cool and warm thermal power generation. The market offers a large amount of different devices to satisfy thermal load requests with various energy source solutions. Among the available options here is introduced an innovative technology of (Gas Heat Pump) GHP capable of waste heat recovery for hot and cold simultaneous thermal power production. The presented GHP is a compression-based heat pump driven by natural gas engine.The purpose of this study is to compare the performance of the GHP with an (Electric Heat Pump) EHP and an electric chiller coupled with a boiler in terms of management costs and environmental impact. The analysis is performed with reference to cold and warm thermal load required by two different cases of study: a shopping centre and a hotel. Specific environmental temperature profiles are proposed for each month in order to estimate efficiencies variation. The performance comparison takes place in a representative day of every month for each load. Two price profile sub-scenarios are developed for each case study and the performance comparison is provided in terms of primary energy consumption, CO2 production and economic feasibility.

Limitations of the TheraMon® -microsensor in monitoring occlusion therapy.

A proof of principle study showed that the TheraMon® -microsensor can reliably measure wearing times of glasses and occlusion patches while having no discomfort for the bearer. The goal of this study was to identify specific temperature profiles in a larger patient group wearing the microsensor with an occlusion patch on the eye, the forehead or in the trouser pocket. Temperature measurements with microsensors were performed at the orbital rim of the eye, at the forehead and in a trousers pocket of 20 healthy adults. The temperature measurements were analysed comparing the three locations using a repeated-measures anova with a 0.050 two-sided significance level. There was no significant temperature difference in wearing the microsensors at the orbital rim compared to forehead (p=0.507). A significant difference could be detected if the microsensors had been in trousers pockets as compared to being positioned at orbital rim/forehead (p=0.001). The study participants reported easy handling and comfortable wearing. This study demonstrates for the first time that TheraMon® -microsensors are fully operational in monitoring occlusion therapy in a larger group of patients (20 adult study participants). Because of the microsensor's ease of handling further studies in a larger group of children is recommended.

The Role of Temperature on the Diurnal Sucrose Source to Sink Balance

The diurnal fluctuations of carbon from its assimilation within the leaves, its export into the phloem, and its use in sink tissues has been studied in its individual parts for quite some time. In cotton (Gossypium hirsutum L.), the majority of the research concerning diurnal sucrose flux in response to temperature is for the most part greater than a quarter century in age, well before the introduction of modern cultivars. Additionally, diurnal research is lacking of any significant examination of any particular temperature profiles, making it difficult to compare responses from one treatment to another. This summary of research focuses on the diurnal flux occurring from both the source and the sink with special attention on four specific temperature profiles; low night temperatures, high night temperatures, low day temperatures, and high day temperatures. Due to the lack of suitable information inherent in some areas, information from other species was used as needed. It is the authors’ intent that temperature dependent diurnal flux should be reexamined as modern cultivars continue to be developed.

Friction-Spinning - Influence of Tool and Machine Parameters on the Surface Texture

The incremental forming process of “friction-spinning” is suited to the manufacture of functionally graded workpieces made from tubes and sheets with the defined adjustment of material properties. The innovative feature of this new process is the use of process elements from both metal spinning and friction welding. As the workpieces are being processed, friction sub-processes are employed to achieve self-induced heat generation. Compared with conventional spinning processes, this in-process heat treatment permits the extension of existing forming limits and allows more complex geometries to be achieved, together with defined, favorable part properties. These properties, like strength, grain size or surface conditions, can be influenced by the set of specific temperature profiles that prevail during the manufacturing process in combination with the degree of deformation. The temperature profiles can be adjusted by selecting appropriate process and tool parameters in a defined manner. This paper presents the influence of the aforementioned parameters on the surface texture. The results presented start with the analysis of the surface texture development. Following this, the effects of the significant process parameters and tool geometries that give rise to the typical structure and hardness are explained.

Minireactor-based high-throughput temperature profiling for the optimization of microbial and enzymatic processes.

BackgroundBioprocesses depend on a number of different operating parameters and temperature is one of the most important ones. Unfortunately, systems for rapid determination of temperature dependent reaction kinetics are rare. Obviously, there is a need for a high-throughput screening procedure of temperature dependent process behavior. Even though, well equipped micro-bioreactors are a promising approach sufficient temperature control is quite challenging and rather complex.ResultsIn this work a unique system is presented combining an optical on-line monitoring device with a customized temperature control unit for 96 well microtiter plates. By exposing microtiter plates to specific temperature profiles, high-throughput temperature optimization for microbial and enzymatic systems in a micro-scale of 200 μL is realized. For single well resolved temperature measurement fluorescence thermometry was used, combining the fluorescent dyes Rhodamin B and Rhodamin 110. The real time monitoring of the microbial and enzymatic reactions provides extensive data output. To evaluate this novel system the temperature optima for Escherichia coli and Kluyveromyces lactis regarding growth and recombinant protein production were determined. Furthermore, the commercial cellulase mixture Celluclast as a representative for enzymes was investigated applying a fluorescent activity assay.ConclusionMicrotiter plate-based high-throughput temperature profiling is a convenient tool for characterizing temperature dependent reaction processes. It allows the evaluation of numerous conditions, e.g. microorganisms, enzymes, media, and others, in a short time. The simple temperature control combined with a commercial on-line monitoring device makes it a user friendly system.

Hydrological investigation of a multi-stratified pit lake using radioactive and stable isotopes combined with hydrometric monitoring

The internal configuration and hydrological dynamics of meromictic pit lakes is often complex and needs to be studied by different tools including stable and radiogenic isotopes. This study combines a multi-isotopic approach (3Hw, δ2Hw, δ18Ow, δ34SSO4) with meteorological, hydrological and hydrochemical monitoring to deduce the flooding history and hydrological dynamics of a meromictic and deeply stratified pit lake (Cueva de la Mora mine, SW Spain). The mine system is complex and includes horizontal galleries, shafts and large rooms physically connected to the mine pit. Specific conductance and temperature profiles obtained in the pit lake draw a physical structure with four monimolimnetic sub-layers of increasing density with depth. This characteristic stratification with m-scale layers separated by sharp transitional zones is rather unusual in other pit lakes and in most natural lakes. Tritium abundance in the different layers indicates that the deep lake water entered the pit basin between 1971 and 1972 which is coincident with the dates of mine closure. The oxygen and deuterium isotope composition of the different layers describes a marked and stable stratification, with an increasing evaporative influence towards the lake surface and a minimal influence of groundwater flow on the structure and composition of the monimolimnion. This study reveals that the initial stages of flooding (via influx of metal- and sulfate-loaded mine drainage from underlying galleries at different depths) may be essential to imprint a layered physical structure to pit lakes which would be very difficult to explain merely by physical processes. After reaching its present water level and morphology, the monimolimnion of this pit lake seems to have remained essentially isolated and chemically unmodified during decades.

Friction-spinning – Interesting Approach to Manufacture of Complex Sheet Metal Parts and Tubes

Friction-spinning is an innovative incremental forming process that permits the defined adjustment of material properties in a particularly precise manner. The process is characterised by the use of process elements from both metal spinning and friction welding. As the workpieces are being processed, friction sub-processes are employed to achieve self-induced heat generation. Compared with conventional spinning processes, this in-process heat treatment permits the extension of existing forming limits and allows more complex geometries to be achieved, together with defined, favourable part properties. The process thus holds a high potential for the manufacture of functionally graded workpieces, such as complex hollow parts made from tubes and sheets. In order to achieve functional gradation, i.e. to influence the material properties (strength or grain size) in a defined manner, it is essential to be able to set specific temperature profiles. It would be possible to influence these profiles by selecting appropriate process parameters like the feed rate, relative motion and the coefficient of friction. The process characteristics of friction-spinning make it eminently suited to tube processing. A further approach to the manufacture of parts with functionally graded areas is the use of sheet metal blanks as another semi-finished product. The paper will present the corresponding results of basic research into the manufacture of sheet metal parts with the aid of friction-spinning. Here, the influence of significant process parameters, forming strategies and tool systems on both the course and the outcome of the friction-spinning process will be shown. In addition, the differences and correlations that exist between tube and sheet processing will be described and discussed on the basis of parts made of tubes and sheets. These parts are manufactured by the friction-spinning process employing different process strategies and tool setups.

Kinetics of Melt Crystallization of a Sunflower Oil‐Based Polyunsaturated Fatty Acid Mixture

AbstractImportant parameters like supercooling and cooling rates affecting the melt crystallization of a polyunsaturated fatty acid (PUFA) mixture obtained from sunflower oil were investigated and compared via high‐resolution polarized‐light microscopy. PUFA was thermally characterized in a differential scanning calorimeter and the significant liquid‐solid‐phase transition temperatures determined were then implemented in the development of specific temperature profiles. Analyzed between two glass slides, induction times were found to decrease with low crystallization temperatures and the number of nuclei per unit area increased with higher supercooling and cooling rates. A comparison between the linear crystal growth rates of pure standards of each of the main fatty acids present in the PUFA mixture and the PUFA mixture itself indicated that the latter is much slower than that of each of its pure components.

A rate based model of a packed column for CO2 absorption using aqueous monoethanolamine solution

A comprehensive and simplified rate based mathematical model of a packed column for CO2 capture using aqueous monoethanolamine (MEA) solution is developed. The absorption unit model takes into account the effect of kinetic reactions on the mass transfer, the thermodynamic non-idealities, the hydraulics of the random packing and the absorber dimensions (diameter and height). It is implemented into the optimization environment GAMS (General Algebraic Modeling System).The proposed NLP model was validated by comparison of obtained results with published experimental data. Good accuracy of results has been obtained for experimental pilot plant scales. Once validated, the model was used to investigate the influence of main process parameters and the effect of different correlations to compute the effective interfacial area for mass transfer (a/at) on the absorption efficiency. Obtained results indicate that model solutions depend strongly on the correlations used to compute the (a/at). In addition, results assuming thermal equilibrium and thermal non-equilibrium in liquid and vapor phases were also compared. For both conditions and specific cases, similar concentration and temperature profiles in the liquid phase in the absorber were obtained.Finally, results obtained by solving different optimization problems are discussed. More precisely, the optimization consisted in determining the operating conditions to maximize the absorption efficiency defined as the ratio between the CO2 recovery in rich solution and the packing volume of the column. The effect of the main process parameters on the optimized results was also investigated.

Spent fuel pool storage calculations using the ISOCRIT burnup credit tool

In order to conservatively apply burnup credit in spent fuel pool criticality safety analyses, Westinghouse has developed a software tool, ISOCRIT, for generating depletion isotopics. This tool is used to create isotopics data based on specific reactor input parameters, such as design basis assembly type; bounding power/burnup profiles; reactor specific moderator temperature profiles; pellet percent theoretical density; burnable absorbers, axial blanket regions, and bounding ppm boron concentration. ISOCRIT generates burnup dependent isotopics using PARAGON; Westinghouse’s state-of-the-art and licensed lattice physics code. Generation of isotopics and passing the data to the subsequent 3D KENO calculations are performed in an automated fashion, thus reducing the chance for human error. Furthermore, ISOCRIT provides the means for responding to any customer request regarding re-analysis due to changed parameters (e.g., power uprate, exit temperature changes, etc.) with a quick turnaround.

Vertical Moist Thermodynamic Structure of the Madden–Julian Oscillation in Atmospheric Infrared Sounder Retrievals: An Update and a Comparison to ECMWF Interim Re-Analysis

Abstract The large-scale vertical moist thermodynamic structure of the Madden–Julian oscillation (MJO) was documented using the first 2.5 yr (2002–05) of version 4 atmospheric specific humidity and temperature profiles from the Atmospheric Infrared Sounder (AIRS). In this study, this issue is further examined using currently available 7-yr version 5 AIRS data (2002–09) to test its dependence on the AIRS data record lengths, AIRS retrieval versions, and MJO event selection and compositing methods employed. The results indicate a strong consistency of the large-scale vertical moist thermodynamic structure of the MJO between different AIRS data record lengths (2.5 vs 7 yr), different AIRS retrieval versions (4 vs 5), and different MJO analysis methods [the extended empirical orthogonal function (EEOF) method vs the multivariate empirical orthogonal function (MEOF) method]. The large-scale vertical moist thermodynamic structures of the MJO between the AIRS retrievals and the ECMWF Interim Re-Analysis (ERA-Interim) products are also compared. The results indicate a much better agreement of the MJO vertical structure between AIRS and ERA-Interim than with the NCEP–NCAR reanalysis, although a significant difference exists in the magnitude of moisture anomalies between ERA-Interim and AIRS. This characterization of the vertical moist thermodynamic structure of the MJO by AIRS and ERA-Interim offers a useful observation-based metric for general circulation model diagnostics.

Selective expression of the soluble product fraction in Escherichia coli cultures employed in recombinant protein production processes

Recombinant proteins produced in Escherichia coli hosts may appear within the cells' cytoplasm in form of insoluble inclusion bodies (IB's) and/or as dissolved functional protein molecules. If no efficient refolding procedure is available, one is interested in obtaining as much product as possible in its soluble form. Here, we present a process engineering approach to maximizing the soluble target protein fraction. For that purpose, a dynamic process model was developed. Its essential kinetic component, the specific soluble product formation rate, if represented as a function of the specific growth rate and the culture temperature, depicts a clear maximum. Based on the dynamic model, optimal specific growth rate and temperature profiles for the fed-batch fermentation were determined. In the course of the study reported, the mass of desired soluble protein was increased by about 25%. At the same time, the formation of inclusion bodies was essentially avoided. As the optimal cultivation procedure is rather susceptible to distortions, control measures are necessary to guarantee that the real process can be kept on its desired path. This was possible with robust closed loop control. Experimental process validation revealed that, in this way, high dissolved product fractions could be obtained at an excellent batch-to-batch reproducibility.

Shape memory behaviour in auxetic foams: Mechanical properties

Abstract Shape memory is the property of a material to remember its original shape despite subsequent plastic deformation. The exposure to specific temperature profiles induces a shape memory effect on auxetic (negative Poisson’s ratio) foam specimens, returning them to their initial dimensions. This behaviour is a one-way effect, and it is a property of the polyurethane (PU) constituent of the foam. The foam specimens were transformed from conventional Poisson’s ratio to auxetic, returned to conventional and once again to auxetic under multiple mechanical and thermal loading. At each stage the foams were mechanically characterized under cyclic tensile and compressive loading. The manufacturing route adopted for the auxetic PU specimens involved a multiaxial compression of the native foam, heating of the compressed specimens above the Tg of the foam polymer, and cooling under running water. Twenty specimens, divided equally between two varieties of PU-based foam, were fabricated. Two different compression ratios were used during auxetic conversion for both kinds of foam, and the same final temperature of 135 °C was adopted. Tensile and compressive cyclic tests were performed in order to measure the tangent modulus (i.e. stiffness), Poisson’s ratios and energy dissipated per unit volume. Remarkable differences before and after the memory effect took place were found, showing mechanical behaviour unique to each of these phases. The shape memory effect plays an important role in the mechanical behaviour of the auxetic foams.

Ten-year global distribution of downwelling longwave radiation

Abstract. Downwelling longwave fluxes, DLFs, have been derived for each month over a ten year period (1984-1993), on a global scale with a spatial resolution of 2.5x2.5 degrees and a monthly temporal resolution. The fluxes were computed using a deterministic model for atmospheric radiation transfer, along with satellite and reanalysis data for the key atmospheric input parameters, i.e. cloud properties, and specific humidity and temperature profiles. The cloud climatologies were taken from the latest released and improved International Satellite Climatology Project D2 series. Specific humidity and temperature vertical profiles were taken from three different reanalysis datasets; NCEP/NCAR, GEOS, and ECMWF (acronyms explained in main text). DLFs were computed for each reanalysis dataset, with differences reaching values as high as 30 Wm-2 in specific regions, particularly over high altitude areas and deserts. However, globally, the agreement is good, with the rms of the difference between the DLFs derived from the different reanalysis datasets ranging from 5 to 7 Wm-2. The results are presented as geographical distributions and as time series of hemispheric and global averages. The DLF time series based on the different reanalysis datasets show similar seasonal and inter-annual variations, and similar anomalies related to the 86/87 El Niño and 89/90 La Niña events. The global ten-year average of the DLF was found to be between 342.2 Wm-2 and 344.3 Wm-2, depending on the dataset. We also conducted a detailed sensitivity analysis of the calculated DLFs to the key input data. Plots are given that can be used to obtain a quick assessment of the sensitivity of the DLF to each of the three key climatic quantities, for specific climatic conditions corresponding to different regions of the globe. Our model downwelling fluxes are validated against available data from ground-based stations distributed over the globe, as given by the Baseline Surface Radiation Network. There is a negative bias of the model fluxes when compared against BSRN fluxes, ranging from -7 to -9 Wm-2, mostly caused by low cloud amount differences between the station and satellite measurements, particularly in cold climates. Finally, we compare our model results with those of other deterministic models and general circulation models.