Performance Evaluation of Concentric Triple Tube Heat Exchanger by using CFD

The main objective of this work is to design a concentric three-cylinder heat exchanger for better heat movement, using a sum of four expansions to verify its hot presentation under similar boundary conditions. For this reason, the second creep condition is specified for robust dividers where the heat flow for the outer side divider is concentrated to achieve an adiabatic state while the dividers and inner vanes of the cylinder are coupled. The deltas for the outside and inside of the line are characterized as mass flow trees; The power source is marked as an outlet with a pressure factor. Flow programming is used to determine the movement of liquid and heat flow in the measurement zones. The applicable conditions are governed iteratively by the limited volume details with the SIMPLE calculation. The RNG-k-epsilon model is used for storm currents because the impact of eddies on strong currents is more accurate than the standard k-epsilon model and the second booster graph method is used for the deflection of the eruptive energy and the its propagation speed. The results show that computer examination of the liquid elements of a concentric three-tube heat exchanger with inclined scales at 45 ° C provides the circulation temperature, the speed of heat movement, and, in general, a coefficient of thermal movement. more than 11.74% higher than sloped blades are at 30 ° C and 28.96% higher than straight stairs, 9mm high and 42.22% higher than three tube heat exchangers concentric fins.

CARACTERIZAÇAO DE DANOS EM EDIFÍCIOS HISTÓRICOS: ESTUDO DE CASO EM QUATRO EDIFICAÇÕES DO MÉDIO OESTE DO RN

RESUMO: A conservação e manutenção das construções históricas é fundamental para transferência de conhecimento e perpetuação do patrimônio da sociedade. O estudo da patologia das edificações contribui para identificação dos mecanismos, causas e origens de problemas que afetem a vida útil dessas edificações. O objetivo do trabalho foi realizar uma avaliação das manifestações patológicas nas edificações de importância história em municípios do Médio Oeste do estado do Rio Grande do Norte, situado no Nordeste brasileiro. Os procedimentos metodológicos empregados envolveram o levantamento da importância histórica e a inspeção in loco, feita com aplicação de Fichas de Identificação dos Danos, registro fotográficos e medições. A Matriz de Gravidade, Urgência e Tendência (GUT) foi utilizada para definir a prioridades nas intervenções futuras. Destacaram-se a ocorrência de: infiltrações; retração e expansão da alvenaria por absorção de água; retração e expansão por movimentação térmica; agentes biológicos e suas excreções; e ineficiência de elementos usados como verga. Como terapias sugeridas, indicam-se técnicas com selagem com resina epóxi ou uso de nata de cimento com consistência adequada nas fissuras, e para as manchas, degradação, descascamento e disgregação a remoção das partes afetadas e preparação do local para ser repintado ou aplicado novo revestimento. A ordem de priorização indicou a sequência de correções: substituição de madeiramento de cobertura, tratamento das fissuras, desagregação, disgregação, descascamento e manchas. ABSTRACT: The conservation and maintenance of historic buildings is essential for the transfer of knowledge and perpetuation of society's heritage. The study of the pathology of buildings contributes to the identification of mechanisms, causes and origins of problems that affect the useful life of these buildings. The objective of the work was to carry out an evaluation of the pathological manifestations in buildings of historical importance in cities in the Middle West of the state of Rio Grande do Norte, located in the Northeast of Brazil. The methodological procedures employed involved the survey of historical importance and on-site inspection, carried out with the application of Damage Identification Sheets, photographic records and measurements. The Gravity, Urgency and Tendency Matrix (GUT) was used to define priorities for future interventions. The occurrence of: infiltrations; masonry retraction and expansion by water absorption; retraction and expansion by thermal movement; biological agents and their excretions; and inefficiency of elements used as lintels. As suggested therapies, techniques with sealing with epoxy resin or use of cement cream with adequate consistency in the cracks are indicated, and for stains, degradation, peeling and disgregation the removal of the affected parts and preparation of the site to be repainted or applied again coating. The order of prioritization indicated the sequence of corrections: replacement of covering wood, treatment of cracks, disintegration, disgregation, peeling and stains.

Micro-Mechanism Research into Molecular Chains Orientation Synergistically Induced by Carbon Nanotube and Shear Flow in Injection Molding

For the degree of orderly arrangement of the molecular chains at the interface of nanocomposites, the static and sheared polyethylene (PE)/carbon nanotube (CNT) models and the sheared pure PE model were constructed, and molecular simulation experiments were carried out in comparison. The micro-mechanism of molecular chains orientation, synergistically induced by the carbon nanotube and shear flow in injection molding, was discussed by analyzing the radius of gyration, molecular chain motion, conformation evolution of molecular chains, bond orientation parameter, interface binding energy and atom distribution. The results show that, for the static composite system, the conformation adjustment of PE molecular chains induced by CNT is limited due to the hindrance from the surrounding chains. Thus, the orientation and radius of gyration of molecular chains increase slightly. For the sheared pure PE system, the orientation induced by shear flow is unstable. After the cessation of shear, the molecular chains undergo intense thermal movement and relax quickly. The disorientation is obvious, and the radius of gyration decreases considerably. It is worth noting that for the sheared composite system, shear flow and the CNT have a synergistic effect on the orientation of the molecular chains, which is due to the adsorption effect of the CNT on shear-induced oriented chains and the inhibition effect of CNT on the relaxation of shear-induced oriented chains. Thus, the orientation stability of PE chains is greatly improved, and interface crystallization is promoted. Moreover, because of the more regular arrangement of molecular chains in the sheared composite system, more H atoms and C atoms are close to the surface of the CNT, which increases the van der Waals force, and correspondingly increases the interface binding energy.

Analysis of CCR Expansion Joints

The CCR (Continuous Catalytic Reforming) Platforming™ process is Honeywell UOP’s technology to convert low octane naphtha to high octane fuel or petrochemical feedstock such as aromatics. It is accomplished in a hydrogen atmosphere at elevated temperature and pressure across a platinum containing catalyst. The process flow is routed through heaters, blowers and coolers between reactors to maintain the heat of reaction. This article captures the procedure of selecting a suitable expansion joint for absorbing thermal movement between two important pieces of CCR equipment — the regeneration cooler and regeneration blower. It shows the design calculations of a universal hinged expansion joint operating at 0.14 MPa and 593°C in a pipe of 762mm diameter. The joint contains 5 single-ply INCOLOY 800H bellows with unreinforced convolutions. Design calculations of the expansion joint have been carried out using formulae prescribed in the Expansion Joints Manufacturers Association (EJMA) standard. Since it is difficult to quantify stresses using a movement test, the EJMA calculations have been verified against finite element analysis results of the bellows.

Preparation of high-performance polyethylene tubes under the coexistence of silicone cross-linked polyethylene and rotation extrusion

In this study, the silicone cross-linked polyethylene (Si-XLPE) powder with better thermoplastic performance and abundant cross-linked network points was attained by using solid-state shear mechanochemical (S 3 M) technology and it was added into high-density polyethylene (HDPE) matrix to prepare Si-XLPE/HDPE tubes by a rotation extrusion rheometer. SEM and 2D-SAXS experiments showed that the presence of Si-XLPE and rotation extrusion facilitated the formation of stable shish-kebabs which deviated from the axial direction in polyethylene (PE) tubes. This result was interpreted that introduction of Si-XLPE in PE tubes provided abundant molecular cross-linked network structures, which suppressed the thermal movement and relaxation of oriented molecular chains owing to intermolecular interaction. Moreover, the axial and hoop flow field further promoted orientation of the permanent cross-linked network entanglement points and formation of more stable cluster-like shish structures in the off-axial direction during the rotation extrusion process. Besides, our experimental results had also ascertained that molecular orientation and shish-kebabs in off-axial direction should be the primary responsibility for the remarkable enhancement of hoop torsional strength in PE tubes. Hoop torsional strength of PE tubes adding Si-XLPE reached 19.58 MPa when the mandrel rotation rate was 30 r.p.m., while that of conventional extruded PE tubes was only 9.83 MPa. As a consequence, PE tubes with excellent performance were prepared under the combined effect of Si-XLPE and rotation extrusion.

Research on Effective Temperature of T‐Shaped Girder for Jointless Bridges in China

<p>Jointless bridge has been proved to be a cost‐effective alternative to bridges with conventional joints. The longitudinal thermal movement of the superstructure is usually considered as the key parameter for designing jointless bridges. The average temperature of cross‐sections can be considered as the effective temperature of the superstructure. In order to accurately estimate the longitudinal thermal movement of the superstructure, the average temperature of cross‐sections should be obtained. The temperature distribution on cross‐sections of T‐shaped girders in one jointless bridge was monitored. A finite element model was implemented using the MIDAS‐FEA software, which is verified based on the monitoring results. Considering the historical extreme temperature conditions and the results of the parametric study, the peak values of the average temperature of T‐shaped girder cross‐sections for jointless bridges in different climate regions in China are recommended. Finally, the simplified formulae to predict the effective temperatures of T‐shaped girder cross‐sections for jointless bridges are proposed based on the correlation analysis.</p>

Study of Reactor Internal Bolt Behaviors Under Lateral Loads

In calculating the bolt stresses under lateral loads, such as caused by the differential thermal movement between two components — problems often found in the reactor internal design, the boundary condition of the bolt is usually conservatively assumed to be in a guided-cantilever beam mode, i.e., the bolt head is not allowed to rotate. In reality, the bolt head could rotate to a certain degree and, furthermore, the bolt head could slip, a form of loosening, under the lateral loads. A series of lateral load-deflection tests was conducted on bolts of different sizes and different lengths, with different preloads, to study the bolt behaviors, including when the bolts start to slip and what is the effect of preloading on the slippage. Furthermore, finite element studies were conducted to correlate the test results to find the proper boundary condition to be used in the bolt stress calculation.