Advanced solar assisted desiccant and evaporative cooling system equipped with wet heat exchangers

This work concerns an innovative solar assisted desiccant and evaporative cooling (DEC) system for building air conditioning. In this system, air-to-air packaged wet heat exchangers are used to maximize the exploitation of the evaporative cooling potential associated with the exhaust air stream.The thermodynamic cycle is first theoretically described, and then an example of a real application is shown.The system presented is an experimental DEC system originally installed at the beginning of 2008 at the Solar Laboratory of the University of Palermo and recently modified and updated. These modifications have been implemented with the aim to foster some problems related to the conventional indirect evaporative process and to increase the overall performance of the process.Different energy performance figures, such as thermal and electrical COP, are presented and discussed.The obtained results are very positive, showing that DEC systems can benefit from the use of wet heat exchangers to efficiently cool the air stream after the adsorption process in the desiccant wheel without any change in moisture content.     

Kinetics and Mechanisms of Dolime Dissolution in Steelmaking Slag

Metallurgical and Materials Transactions B - The kinetics of dolime dissolution containing 20 and 50 pct of magnesium oxide in steelmaking slags has been studied in a high-temperature...     

Experimental studies on the positive feedback effect of progesterone, 17 alpha-hydroxyprogesterone and 20 alpha-dihydroprogesterone on the pituitary release of LH and FSH in the human female. The estrogen priming of the progesterone feedback on pituitary gonadotropins in the eugonadal woman

Administration of progesterone eugonadal women during the midfollicular phase of the menstrual cycle failed to induce a positive feedback effect on the serum concentrations of LH and FSH. The levels of estradiol in serum decreased following the injection of progesterone without a parallel change in LH and FSH concentrations indicating a direct ovarian effect of the exogenous progesterone. In the late follicular phase of the cycle, when preovulatory levels of estradiol were present in serum, or under a ethinyl estradiol treatment progesterone was able to induce an LH discharge indicating the requirement of an estradiol priming of the positive feedback of progesterone in eugonadal women. In order to establish the time required for a sufficient estrogen priming with preovulatory levels of estradiol in serum 3 mg of estradiol-benzoate were administered i.m. 1, 12 and 24 h prior to the administration of 30 mg of microcristalline progesterone in the midfollicular phase of the menstrual cycle, when progesterone alone did not cause an LH surge. Only when estradiol-benzoate was injected 24 h prior to the progesterone administration an LH surge reproducible in time course and magnitude occurred. Administration of estradiol-benzoate alone under these conditions did not cause an LH surge within the elapse of time after the injection when the progesterone induced LH surge occurred. Thus, these experiments demonstrate that a defined estrogen priming is required for the positive feedback effect of progesterone on the gonadotropin release in eugonadal women. Furthermore, progesterone levels in serum of about only 1--2 ng/ml were required for the induction of an LH surge indicating that under physiological conditions progesterone may have an supplementory effect on the primarily estradiol induced LH midcycle peak. 17-hydroxyprogesterone administered during the mid follicular phase of the menstrual cycle and under pretreatment with ethinyl estradiol failed to induce a positive feedback effect on the serum concentrations of LH and FSH, indicating that this steroid does not play a regulatory role on the midcycle LH release in women. 20alpha-dihydroprogesterone administered under the same experimental conditions as 17-hydroxyprogesterone seems to be able to induce an LH surge in serum provided there is an adequate estrogen priming.     

Innovative Catalysts for Oxidative Dehydrogenation in the Gas Phase – Metallic Short Fibers and Coated Glass Fabrics

The catalytic activity of metallic short fibers with chosen alloy components and textures was investigated in the oxidative dehydrogenation (ODH) of propane to yield propene, and of isopropanol to yield acetone. The short fibers were synthesized using a melt extraction process and the properties of the fibers were intensely characterized. A correlation between the structure and the catalytic activity of the material was established. Optical microscopic, DSC, XRD, REM and EDX methods were used to characterize the fibers. Selective results of the dependency of the temperature on the propane conversion are presented in this work. A yield of more than 35 % propene is obtained at a propane conversion of 50 %. The ODH of isopropanol to acetone occurred with attractive yields of over 80 %. The results demonstrate the high innovative potential of the metal fiber materials. The use of coated glass fabrics as catalysts for the ODH and total oxidation of propane were also part of this investigation.     

High temperature resistant insulated hybrid yarns for carbon fiber reinforced thermoplastic composites

With the increased use of carbon fiber reinforced composites (CFRC), the demand for the integration of insulated conductive wire/yarns in CFRC is increasing for additional function integrations such as sensoric, actoric, signal transfer, heating, etc. Between thermoset and thermoplastic matrix composites, the integration of insulated conductive materials is comparatively difficult due to the requirements of higher temperature and pressure during the consolidation of thermoplastic composites. Therefore, the need for insulating material able to withstand higher temperature for the use in thermoplastic CFRC is also high. Using DREF friction spinning technique, it is possible to manufacture yarns with a core‐sheath structure in which, as the core conductive wire/yarns and as the sheath different fiber formed materials can be used for the insulation of the core. In this study, the aspects of using different short/staple fibers such as polyester, Glass and Kynol as the sheath and the usable temperature range are revealed. Furthermore, the insulation property of such fibers after the application of different temperatures has been reported. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1179‐1184, 2013     

Energy and economic assessment of desiccant cooling systems coupled with single glazed air and hybrid PV/thermal solar collectors for applications in hot and humid climate

This paper presents a detailed analysis of the energy and economic performance of desiccant cooling systems (DEC) equipped with both single glazed standard air and hybrid photovoltaic/thermal (PV/t) collectors for applications in hot and humid climates. The use of ‘solar cogeneration’ by means of PV/t hybrid collectors enables the simultaneous production of electricity and heat, which can be directly used by desiccant air handling units, thereby making it possible to achieve very energy savings. The present work shows the results of detailed simulations conducted for a set of desiccant cooling systems operating without any heat storage.System performance was investigated through hourly simulations for different systems and load combinations. Three configurations of DEC systems were considered: standard DEC, DEC with an integrated heat pump and DEC with an enthalpy wheel. Two kinds of building occupations were considered: office and lecture room. Moreover, three configurations of solar-assisted air handling units (AHU) equipped with desiccant wheels were considered and compared with standard AHUs, focusing on achievable primary energy savings.The relationship between the solar collector’s area and the specific primary energy consumption for different system configurations and building occupation patterns is described. For both occupation patterns, sensitivity analysis on system performance was performed for different solar collector areas. Also, this work presents an economic assessment of the systems. The cost of conserved energy and the payback time were calculated, with and without public incentives for solar cooling systems. It is worth noting that the use of photovoltaics, and thus the exploitation of related available incentives in many European countries, could positively influence the spread of solar air cooling technologies (SAC). An outcome of this work is that SAC systems equipped with PV/t collectors are shown to have better performance in terms of primary energy saving than conventional systems fed by vapour compression chillers and coupled with PV cells.All SAC systems present good figures for primary energy consumption. The best performances are seen in systems with integrated heat pumps and small solar collector areas. The economics of these SAC systems at current equipment costs and energy prices are acceptable. They become more interesting in the case of public incentives of up to 30% of the investment cost (Simple Payback Time from 5 to 10 years) and doubled energy prices.     

Sampling phased array technology for the detection of voids in carbon fiber-reinforced plastics

In the lightweight material industries, the current focus is on fiber-reinforced plastics, in particular on carbon fiber-reinforced plastics (CFRPs), since they offer higher relative specific tensile strength and stiffness as well as reduced weight compared to conventional metallic materials. Currently, the quality assurance of manufactured CFRP components represents a major challenge for CFRP manufacturers. Voids are generated during the infusion process of CFRPs, which in turn reduce the mechanical performance of CFRPs. This article presents the possibility to detect the distribution of voids across the surface of CFRPs by using a non-destructive testing method, the so-called sampling phased array ultrasound technology. Two types of CFRPs with six carbon layers in the same direction are fabricated by means of a vacuum-assisted resin infusion process. Voids in CFRPs are generated using a foaming agent during the impregnation process. The C-scan images produced through the sampling phased array technology are subsequently analyzed by the optical image analysis software in order to determine the amount of voids for each type of manufactured CFRP.     

Entwicklung und Aufbau einer Meßmethode zur realitätsnahen Beurteilung des Spaltkorrosionsverhaltens am Beispiel von Aluminiumwerkstoffen

Development and construction of a measuring technique for a realistic evaluation of the crevice corrosion behaviour by way of aluminium alloys Aluminium alloys represent a high percentage of materials used in aircraft. Complex designs such as those found in the aircraft industry illustrate a number of constructively determined geometrical crevices. As always the crevice corrosion behaviour of materials is difficult to reconstruct and evaluate in a laboratory. The authors present an experimental set up which reflects the situation in constructively determined crevices. It will be shown, with the use of selected aluminium alloys, that a quite good evaluation of crevice corrosion behaviour of materials is possible. The acidification and enrichment of selected species can be observed very well and their reaction on crevice corrosion can be semi‐quantitatively estimated. The interpretation of the corrosion results is overall improved.