A calorimetric method is applied to determine the solar system performance by in-situ measured data. The heat store is interpreted as a calorimeter and the information on charge and discharge is extracted from the shape analysis of the heat store’s temperature profile. The method is applicable to any heating system which includes a heat store. In the present paper, this procedure is presented and applied to determine the solar gain for a large solar system for domestic hot water preparation and a solar combisystem. The uncertainty of this method is in the range of ±10%. The results obtained by the calorimetric method are compared to TRNSYS simulations. 相似文献
We have examined the esterification of [3H]cholesterol following the intratracheal instillation of a tracer amount into the isolated rat lung perfused with Krebs bicarbonate
containing 4.5% albumin. At 5, 30 and 60 min after instillation, lungs were lavaged at 2°C with 3×10 ml of 0.15 M NaCl, each
volume instilled and withdrawn three times. Each lung was lavaged at only one time point. The saline recovered was centrifuged
at 150 g (5 min) to sediment the macrophage-rich fraction, leaving the surfactant in the supernatant. The amounts and specific
activity of cholesterol and cholesteryl ester were measured following isolation by high performance liquid chromatography
of the free cholesterol and the hydrolyzed ester-derived cholesterol. There was a rapid fall in [3H]cholesterol in the surfactant fraction, accompanied by a reciprocal increase in [3H]cholesteryl ester. Likewise, there was a rapid increase in [3H]cholesteryl ester in the macrophage-rich fraction, while the level of free [3H]cholesterol in that fraction remained very low. These data are consistent with exogenous cholesterol being rapidly esterified
in the alveolus, and the ester then being cleared by the macrophages. We were unable to locate the actual site of esterification.
Lipids 相似文献
Alumina composites reinforced with 20 vol% SiC whiskers were exposed to applied stresses in four-point flexure at temperatures of 1000°, 1100°, and 1200°C in air for periods of up to 14 weeks. At 1000° and 1100°C, an "apparent" fatigue limit was established at stresses of ∼ 75% of the fast fracture strength. However, after long-term (>6 weeks) tests at 1100°C, some evidence of crack generation as a result of creep cavitation was detected. At 1200°C applied stresses as low as 38% of the 1200°C fracture strength were sufficient to promote creep deformation and accompanying cavitation and crack generation and growth resulting in failures in times of <250 h. 相似文献
A precursor of boron nitride was prepared through the partial condensation of 2,4,6-trichloroborazine and bis-(trimethylsilyl)acetylene. This reaction was conducted at 100°C and is catalyzed by AlCl3. The condensation product pyrolyzed at 800°C, producing trimethylsilyl chloride as a volatile product and a boron nitride rich residue containing 54 wt% of the initial weight. Mixtures of the precursor and commercial boron nitride were made and hot-pressed at 800°C and 27.6 MPa. A maximum density of 1.84 g/cm3 is reached at a loading corresponding to the deposition of 13 wt% residue derived from the precursor. Examination by analytical electron microscopy, including X-ray energy dispersive spectroscopy and electron energy loss spectroscopy analyses, revealed the location of material derived from the precursor in BN-binder composites through the presence of residual aluminum, silicon, and carbon. Crystallization of boron nitride from the precursor appears to have taken place, as deduced from the morphology of the phases observed and association with residual elements present in the binder. 相似文献
Pyrolysis of lignin is one approach that has been investigated to upgrade this material into higher value products. However, there have been relatively few efforts to quantitatively model these reactions. This paper describes a methodology for modeling lignin pyrolysis which has been extensively developed for related materials like coal. The samples are characterized using pyrolysis experiments under a standard set of conditions, where the products are analyzed by Fourier Transform Infrared (FT-IR) Spectroscopy and Field Ionization Mass Spectrometry (FIMS). Solvent extraction experiments are done to determine the extractables yields and elemental analysis is done to further constrain the model.
One lignin, produced from ethanol/water extraction of mixed hardwoods, was selected for the application of this modeling approach. The model was able to qualitatively predict the tar molecular weight distributions and quantitatively predict the variations of the gas and tar evolution rates and yields with heating rate for the calibration set of experiments. The model can be improved by more precise information on lignin structure, crosslinking chemistry, and tar transport mechanisms. It also needs to be validated by simulation of pyrolysis conditions at high heating rates and/or high pressures for which data is currently not available. 相似文献
The product from the hydrogenation of an iron-tin treated Morwell, Victorian coal was separated into a number of fractions by solvent separation. Each of these fractions (tetrahydrofuran-insoluble materials, asphaltols, asphaltenes and oils) was reacted separately with hydrogen in tetralin both with and without added catalysts. The effect of added catalyst and of temperature, pressure, time and solvent on the hydrocracking and repolymerization reactions is discussed. The interconvertibility of the brown coal-derived products is clearly established, reinforcing the importance of incorporating reversibility of reactions in mechanistic models developed to describe coal hydroliquefaction. 相似文献
The thermoplastic properties of ten coals of rank 301a to 902 in the NCB Classification Scheme have been investigated using a high pressure dilatometer. The results show that the swelling behaviour of a coal at high pressure cannot be accurately predicted from a single measurement under standard conditions (3°C min?1, 0.1 MPa). The data also clearly show that the large differences in dilatation observed under standard conditions for the range of coals investigated are much reduced at high pressures, e.g. > 4 MPa. The trends in dilatometry parameters in relation to rank and pressure are discussed in detail. The relative order of coals based on dilatation may change with increase in pressure and this mainly occurs in the pressure range up to 2.5 MPa. The results suggest that the characterization of coals for high pressure gasifiers should include measurements under simulated gasifier conditions rather than standard tests at atmospheric pressure. 相似文献
Investigations on the scope and utility of exo-mechanism proximity-accelerated reactions in engineered receptor-ligand systems are reported. We synthesized a series of electrophilic cyclosporin (CsA) derivatives by varying electrophiles and linker lengths, prepared a series of nucleophilic cysteine mutations on the surface of cyclophilin A (Cyp), and examined their reactivity and specificity in proximity-accelerated reactions. Acrylamide and epoxide electrophiles afforded useful reactivity and high specificity for alkylation of engineered receptors in Jurkat cell extracts. We found that remote cysteines (>17 A from the ligand) could be alkylated with useful rates under physiological conditions. The results from mutations of the receptor surface suggest that the dominant factors governing the rates of proximity-accelerated reactions are related to the local environment of the reactive group on the protein surface. This study defines several parameters affecting reactivity in exo-mechanism proximity-accelerated reactions and provides guidance for the design of experiments for biological investigations involving proximity-accelerated reactions. 相似文献
Ceramics of the melilite-type compound La1+ x Sr1− x Ga3O7−δ were prepared by conventional ceramic processing. Samples prepared represented the entire homogeneity region of the phase (i.e., x =−0.15 to 0.60). Electrochemical characterization under variable temperature and atmospheric conditions in the vicinity of air entailed four-point direct-current conductivity measurements and electromotive force measurements. La1+ x Sr1− x Ga3O7−δ samples exhibited a p -type behavior with generally increased conductivity with increased substitution of lanthanum for strontium, which reached a saturation value of ∼10−1 S·cm−1 at 950°C. 相似文献