Influence of Fins Number and Frosting on Heat Transfer through Longitudinal Finned Tubes of LNG Ambient Air Vaporizers

The use of cryogenic liquefied gasses in industry is constantly increasing both for process purposes and for power supply needs. The liquefied natural gas (LNG) is stored at cryogenic temperature and its immediate use in gaseous form requires its evaporation. The heat needed to cause a phase change is usually delivered by means of vaporizers. This paper presents a numerical analysis of the influence of the fins number and frost accumulated within the fins surface on the heat transferred through the aluminum finned tubes of LNG ambient air vaporizers. The calculations were carried out applying finite element thermal analysis within Ansys software as well as using an analytical approach. As a result, the heat rate per unit length of the finned tube was obtained. The results were compared for different numbers of longitudinal fins both without frost and for total frosting of the tubes.

Effect of two types of ozone treatments on the quality of apple fruits

The aim of this research was to demonstrate the effect of the ozonation process (exposure to ozone in gaseous form and rinsing in water saturated with ozone) on selected apple parameters. The scope of the study included: conducting the ozonation process under controlled conditions at a concentration of 1 ppm and exposure times of 1, 5 and 10 min (ozone in gaseous form) and 10, 15 and 30 min (ozonated water), respectively; polyphenols research; determining antiradical activity using ABTS radicals; and determining the influence of the applied method on the volatiles that give rise to odor chemicals (fragrance and aroma). In both cases, measurements were taken 24 hours after the ozonation process. Both exposure to ozone in gaseous form and washing in ozonated water did not adversely affect the appearance of the fruit. The rinsing process in ozonated water did not significantly affect the composition of the compounds responsible for the fruit’s odor. The proposed washing conditions affected the biochemical balance of the fruit. Differences in polyphenol content and antioxidant potential were noted. The mean content of polyphenols expressed as gallic acid equivalent in the control sample was determined to be 15.22 mg/100 g. In comparing the content of polyphenols with the control sample, insignificant changes in their content were noted, except for the sample with the longest ozonation. In the case of fruit washed within 30 minutes, a significant increase by 53% in antioxidant potential was noted. α- Farnesene was identified as the main component established by headspace solid-phase microextraction (HS-SPME) procedure. The proposed ozonation conditions made it possible to keep the volatile compounds influencing the sensory properties of apples unchanged.

Copper acetate-facilitated transfer-free growth of high-quality graphene advancing hydrovoltaic electricity generators

ABSTRACT Direct synthesis of high-quality graphene on dielectric substrates without a transfer process is of vital importance to aim at a variety of applications. Current strategies for boosting high-quality graphene growth, such as remote metal catalyzation otherwise are limited by poor performance with respect to the release of metal catalysts and hence suffer from the problem of metal residues. Herein, we report an effective approach that utilizes a metal-containing species, copper acetate, to continuously supply copper clusters in a gaseous form to aid transfer-free growth of graphene over a wafer scale. The thus-derived graphene films were found to show reduced multilayer density and improved electrical performance and exhibited a carrier mobility of 8500 cm2 V−1 s−1. Furthermore, droplet-based hydrovoltaic electricity generator devices based on directly grown graphene were found to exhibit robust voltage output and long cyclic stability, in stark contrast to their counterpart based on transferred graphene, demonstrating its potential for emerging energy harvesting applications. The work presented here offers a promising solution to organize the metal catalytic booster toward the transfer-free synthesis of high-quality graphene and enable smart energy generation.

Ozone therapy as complementary treatment for surgical infection: case report.

Background: Infection is a serious surgical complication that increases significantly morbidity and mortality rates as well as health care expenses. Bacterial ever-growing resistance to antibiotics makes the treatment of such events even more troublesome. Objective: Report on a surgical infection case treated with ozone as a complementary therapy. Methods and Materials: Female, 65 years old, submitted to a complex surgical procedure for adult kyphotic deformity correction that presented with early post-surgical infection. The patient was treated with revision surgery and antibiotics that improved the condition but were unable to delete the infection. Ozone, in its gaseous form, was injected subcutaneously and paravertebraly twice weekly for three weeks. Results: After 3 weeks of treatment the wound healed completely and repeated visits and blood exams up to one year after the surgery did not show recurrence of infection. Conclusions: Although not a definite indication on validity of ozone therapy for surgical infections, the results of this case report indicate a new way that merits to be explored.

Modeling the Repair of a Crack in an HDPE Pipe

A pipe is a buried or aerial pipeline carrying goods, whether in liquid or gaseous form. Pipes are most often made from polymer tubes. These pipes prove to be subject to damage caused by a lack of material or crack thus calling for methods of repair or reinforcement.The objective of this study is to analyze by finite element analysis the presence of a horizontal crack in a high-density polyethylene pipe subjected to patch-corrected internal loading.Part of this study is devoted to analyzing the Von Misses stress distribution along a horizontal line, the applied loading type effect, the orientation of the fibers and the nature of the patch have been highlighted.The second part of our study is based on the calculation of the J-Integral where the same parameters of the first part were considered.The results clearly show that the mechanical characteristics of the composite must be optimized to provide an effective repair safely and allow relief of stress concentrations at the crack front.

Finite element analysis of heat flow through longitudinal finned tubes in the LNG ambient air vaporizer for a total frost case

Liquefied natural gas (LNG) is transported and stored in liquid state at temperature of -163C. In order to use natural gas directly in its gaseous form, LNG must be vaporized, which requires the input of heat. Ambient air vaporizers (AAVs) are commonly used for that purpose in LNG regasification stations. These heat exchangers consist of longitudinally finned tubes with a large heat transfer surface area, provide high efficiency and are virtually cost-free since the heat is taken from the ambient air. This paper presents the results finite element thermal analysis of heat transfer through the finned tubes of ambient air vaporizers under the conditions of total frosting.

A Survey of Chemoreceptive Responses on Different Mosquito Appendages

Research on the functions of insect chemoreceptors have primarily focused on antennae (olfactory receptors) and mouthparts (gustatory receptors). However, chemoreceptive sensilla are also present on other appendages, such as the leg tarsi and the anterior wing margin, and their specific roles in chemoreception and mosquito behavior remain largely unknown. In this study, electrophysiological analyses in an electroantennogram recording format were performed on Aedes aegypti (L., Diptera: Culicidae) antennae, mouthparts, tarsi, and wings during exposure to a variety of insect repellent and attractant compounds. The results provide evidence that the tarsi and wings can sense chemicals in a gaseous form, and that the odors produce differing responses on different appendages. The most consistent and strongest response occurred when exposed to triethylamine (TEA). Antennae and mouthparts showed nearly identical responses pattern to all tested compounds, and their rank orders of effectiveness were similar to those of fore- and mid-leg tarsi. Hindleg tarsi only responded to TEA, indicating that the hind legs are not as chemoreceptive. Wings responded to a range of odorants, but with a different rank order and voltage amplitude. Insights gleaned into the function of these appendages in insect chemoreception are discussed.

Study of emission of radioactive gaseous effluents in the production of 18F-FDG

The number of units producing radiopharmaceuticals with a half-life of fewer than two hours has increased with the growth of PET technology in Brazil. In the production of such radiopharmaceuticals such as 18F-FDG or 11C-PIB, gaseous waste is formed. The International Atomic Energy Agency (IAEA) proposes a methodology that can be used to evaluate the dispersion of these gaseous effluents. This work has retrospectively evaluated the emission of radioactive gaseous effluents generated in the production of 18F-FDG, in order, to delimit yield values of radioactive waste in the gaseous form and to verify the effectiveness and the design of the safety elements of the exhaust system evaluated before the standards of the National Nuclear Energy Commission (CNEN) and IAEA recommendations. Thirty-six productions of 18F-FDG were found.

Corrosion of Carbon Free and Bonded Refractories for Application in Steel Ingot Casting: An Approach for Improving Steel Quality

Impurities and resulting inclusions are an issue when processing higher amounts of scrap during steel making. To increase the recycling rate, the removal of impurities from the scrap in form of inclusions is of great interest. In previous studies was found that inclusions attach primarily on carbon containing refractories, especially if on their surface an interfacial layer (1–3 µm thickness) was formed in-situ. This study investigates the formation mechanism of this in-situ layer in detail by application of computer tomography (CT) measurements on two scales. The large scale CT scans visualized the general appearance whereas the small scale measurement regarded the in-situ formed layer and the attached inclusions in detail. Based on these measurements, previous results and a literature review it was concluded that the layer formed mainly due to carbothermally reduced impurities which moved to the decarburized surface of the refractory in gaseous form and enhanced sintering of the surface region to develop the layer.