Liquid CO2 droplet extraction from gases

Efficient mechanical separation of CO₂ from combustion effluent affects the utilization potential of high CO₂ producers such as coal. Novel mechanical separations of condensing CO₂ from gas flows need to be able to capture the small condensed droplets below the cyclone cut-off limit of 20 μm. We describe the thermodynamics, the energy costs and droplet formation of CO₂ phase separation from combustion effluent and natural gas. We report the first measurements of condensing CO₂ droplet sizes from gas. This shows that application of homogeneous condensation of CO₂ yields much smaller droplets in flue gas (N₂/CO₂) than from contaminated natural gas (CH₄/CO₂). These small droplets can only be efficiently removed at high throughputs using the novel centrifugal method we describe. Such mechanical separations are preferable to the current standard chemical methods because of the much lower environmental footprint.     

Characterization of rigid polyurethane foams containing microencapsulated Rubitherm? RT27. Part I

Rigid polyurethane foams (RPU foams) and phase change materials (PCMs) are widely used in buildings for thermal insulation and thermal storage, respectively. The combination of both materials could increase energy savings, leading to more energy efficient housing. In this work, PU foams were produced incorporating different percentages of microcapsules containing Rubitherm^? RT27. Microcapsules added to the foam had a high influence on the foaming process and also on the foam properties. It was observed that the increase of foam microcapsules content decreases the final foam height but increases its density and thermal energy storage (TES) capacity. On the other hand, an increase of the foam microcapsules content up to 5 wt% led to decrease the reduced compressive strength (RS) and modulus (RE) in 7 and 25%, respectively. Higher contents had a sharply negative impact on mechanical properties.     

Role of the phase composition of tungsten containing hard alloys in the formation of a layer of titanium carbide in gas titanizing

Conclusions In gas titanizing of tungsten-containing hard alloys a continuous layer of titanium carbide forms on their surface; its composition, thickness, and microhardness depend on the phase composition of the alloy, in particular on the amount of cobalt phase.When hard alloys contain the phase (Ti, W)C, the thickness of the layer of titanium carbide increases.We discovered selective solubility of the solid solution (Ti, W)C in the cobalt phase in proportion to its decarburization during titanizing; this leads to the formation of ring structure of the grains of (Ti, W)C with higher titanium content on the periphery which, as is known [9], increases the wear resistance of hard alloys.Translated from Poroshkovaya Metallurgiya No. 7(319), pp. 74–79, July, 1989.     

Automation of test bed studies of coal cutting

Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 3, pp. 110–115, May–June, 1988.     

Eddy current solutions applicable to the problem of nondestructive inspection of flat and cylindrical surface layer

Nondestructive inspection of flat and long cylindrical metallic-surface layers is conveniently dealt with using the results of wave propagations in a one-dimensionally stratified medium. Analytical solutions for some special profiles are obtained, and perturbation technique is used to obtain results for more frequently encountered profiles.     

Manufacturing of Surface Relief Structures in Moving Substrates Using Photoembossing and Pulsed‐Interference Holography

Photoembossing is a cost‐effective technique for the production of complex surface relief structures in a photopolymer film, achieved via contact‐mask exposure to UV‐light. Here, photoembossing is explored using interference holography with a CW laser and a nanosecond pulsed laser. It is shown that identical surface relief structures are produced if the photopolymer film is kept in a fixed position. In the case of a moving substrate, relief structures are only obtained with the pulsed laser and the heights of the relief structures and their shape are the same as in the static experiments. This illustrates that photoembossing in combination with pulsed laser interference holography is potentially useful in the production of large area structured films using roll‐to‐roll processes.

     

Poly(lactic acid)/carbon nanotube nanocomposites with integrated degradation sensing

For the first time, an in-situ degradation monitoring system for biodegradable polymers is reported in present work. The proposed concept is based on a conductive biodegradable polymer composite, where carbon nanotubes (CNTs) are incorporated in poly(lactic acid) (PLA) in order to develop an intelligent biocomposite system that can sense biodegradation. Changes in electrical resistivity of the PLA/CNT nanocomposites were successfully correlated with degradation levels of the biopolymer. PLA/CNT nanocomposites demonstrated excellent degradation sensing abilities at CNT concentrations around the percolation threshold, with resistivity changes of about four orders of magnitude with biodegradation. In contrast to many other stimuli, biodegradation resulted in a reduction in resistivity due to an increased CNT network density after partial removal of the amorphous phase of the polymer matrix.     

An explicit analysis of the lead time syndrome: stability condition and performance evaluation

Updating planned lead times in response to changing workload levels leads to erratic ordering behaviour, resulting in even larger variability in the workload levels and flow times. This phenomenon is called lead time syndrome, and describes the cyclic interaction between adaptive planned lead times and order sizes. Although it has been conceptually defined and intuitively accepted, formal analysis with analytical evaluation of the phenomenon has not been conducted. The objective of this paper is to provide a stronger understanding of the lead time syndrome, and to give new insights into the effects of frequently updating planned lead times. We develop a two-dimensional Markov process to model a single-item production process with orders released sensitive to the planned lead time. Using matrix-geometric methods, analytical results on the utilization level and the variability in the system are presented in relation to the frequency of updating the planned lead time. Although the average utilization level is always retained, the lead time syndrome causes an increase in the average workload level and the actual flow times of the completed orders. The variability of the planned lead time increases with the update frequency except at the utilization boundaries, where the relative effect of the update frequency diminishes.     

Experimental analysis of deburring process on inclined exit surface by new deburring tool

The removal of macro-burrs formed after drilling has always been a difficult engineering problem, especially on inclined exit surfaces with intersecting holes. A new deburring tool is developed to remove burrs on inclined exit surfaces. The performance of the proposed deburring tool is analyzed according to changes in parameters including tool geometry, the deburring direction, and cutting conditions. Based on our analysis, proper tool geometry is suggested, and an efficient deburring method and deburring conditions are determined which satisfy the chamfered geometry and surface roughness of holes.