Pipe Test Research Articles

Hysteresis phenomena in flat-type loop heat pipe

Testing of loop heat pipes showed that the heat-load dependence of the operating temperature was not always unambiguous. It may have hysteresis phenomena. The temperature hysteresis had a certain relationship with previous history of the power variation, and also related to the initial parameters of the loop heat pipes. It has been found that the temperature hysteresis of the loop heat pipes was related to the gas-liquid distribution in the compensation chamber which depended on the interaction between heat leak of evaporator and the reflux liquid from condenser. The temperature of the loop heat pipes evaporator rose with the gas phase in the compensation chamber increased.

Fabrication and testing of a miniature flat evaporator loop heat pipe with polydimethylsiloxane and molding

Two main approaches have been proposed to fabricate miniature loop heat pipes: a mechanical-manufacturing-based approach (traditional approach) and a microelectromechanical-system-based approach. However, both of these approaches have problems, such as complexity, expensive equipment, and difficult control. Polydimethylsiloxane and molding are good candidates for solving these problems because they have a low cost and require simple materials and processing. In this study, substrates with high thermal conductivity were combined with Polydimethylsiloxane for the fabrication of a 3.4 mm thick loop heat pipe evaporator. The effect of the molding conditions on the loop heat pipe thermal performance was discussed and the suitable conditions were identified. The heat transfer performance of the miniature loop heat pipe in different orientations was investigated. A long-term performance test was carried out. It was found that the miniature loop heat pipe could operate stably for a long time (three weeks) in different orientations. The maximum heat transfer capacity reached 9 W (4.5 W/cm2) and a thermal resistance of 5.7 K/W was obtained. The maximum heat flux is 2–4 times higher while the thermal resistance is the same order as with the corresponding values of other polymer heat pipes. Further improvement was required for practical applications. However, there was evidence of a high degree of potential with this approach for the miniaturization of loop heat pipes.

Numerical analysis of the transmission loss of water muffler according to the two-load method

A numerical method for the transmission loss prediction of the water muffler has been provided according to the measuring process of the two-load method. The commonly used acoustic loads can be applied in the proposed method. The accuracy of the proposed method has been proved by comparing the calculated transmission loss with that from the traditional direct predicting method. And then the proposed method is used to discuss effects of test bench on transmission loss measurement. The predicted transmission loss curves are consistent reasonably based on different test models. The location of monitors relative to the muffler inlet and outlet has little influence on the result. But the distance between the two monitors upstream or downstream should be controlled within a certain range based on the concerning frequency band and the main pipe diameter. It is found that modes of the coupled system consisting of the test pipes and the water cause extra peaks on the transmission loss curve. The influence can be reduced by arranging appropriate fixed points. The proposed method can be used to to explain the reasonability and validity of the test bench design.

Liquid-phase turbulence measurements in air-water two-phase flows using particle image velocimetry

Liquid-phase turbulence plays a vital role in determining various gas-liquid two-phase flow parameters, such as void fraction distribution, bubble morphology, bubble-bubble interactions, and interfacial area concentration. In this study, a two-phase flow database including both the gas- and liquid-phases measurements was developed focusing on three bubbly flow conditions in an air-water two-phase flow loop with a vertical one-inch diameter circular pipe test section. A particle image velocimetry (PIV) system integrating an optical phase separation method, i.e., the planar laser-induced fluorescence (PLIF) technique using fluorescent particles and optical filtration, was applied to measure the liquid-phase turbulence information, including the time-averaged velocity, Reynolds stress, and turbulent kinetic energy for the liquid phase. The PIV measurements were taken at three ports along the test section at 14.5, 51.5, and 88.5 pipe inner diameters downstream of a bubble injector. In addition, a double-sensor conductivity probe was used to measure radial distributions of the local time-averaged void fraction and gas velocity. The measured liquid-phase turbulence was used to benchmark Sato's turbulence model considering the bubble-induced shear stress for the three tested bubbly flows. The benchmark results showed good agreement between the PIV measurements and model predictions. In the two bubbly flows tested that have low void fractions being less than 3%, the effect of the bubble-induced turbulence was found not significant. However, the bubble-induced shear stress becomes important with the increase of the void fraction.

Physical model tests of lateral pipe–soil interaction including the pipe trajectory in sand

Under the conditions of HT-HP, the subsea pipelines transmitting oil and gas in deep sea water often experience lateral buckling due to the accumulation of axial force. The pipe–soil interaction is one of the most important factors during the lateral buckling. In order to understand the pipe–soil interaction deeply, a series of tests about the pipe–soil interaction with different initial pipe embedments and weights were conducted in sand. A PVC pipe segment with an outer diameter of 16 cm is set as the object of this study. The soil resistance and the trajectories of the pipe segment under different conditions were measured during the test process. According to the test data, a formula for predicting the maximal lateral soil resistance was proposed with the help of R software. Moreover, another formula for calculating the lateral displacement reaching the maximal lateral soil resistance was also proposed. The trajectories of the pipe segment under different conditions were set as models, which greatly simplified the calculation of the track of the pipe segment and presented a good way to predict the movement of pipes.

Experimental Study of Environment-Friendly Underwater Structure-Submerged Floating Tunnel

In order to study the dynamic characteristics of an innovative underwater structure, Submerged Floating Tunnel (SFT), a model test study was carried out in a calibrated experimental tank based on the Qiongzhou Strait cross-sea passage project and considering the effects of wave and current loads. The size of the test tank is 36m (length) x 31m (width) x 3m (depth), which can simulate the effect of wave and current simultaneously. Under the conditions of pure current, pure wave and wave-current coupling, the pressure change of the test pipe is monitored, and the influence of the wave-current load on the surface pressure of the test pipe is analyzed. The experimental results show that the pressure at the inlet side of the test pipe increases with the increase of the current velocity, the wave height and period, regardless of whether the test pipe section is subjected to pure current, pure wave or wave-current coupling.

Experimental and Numerical Analysis of Composite Wick Heat Pipes using Ethanol

Warmth pipes come convenient now-a-days as they work with most noteworthy warmth conductance contrasted with some other method of warmth move and accessible over wide scope parameters. In the present investigation de-ionized water stream in plain thermo siphon, Sintered Copper wick and Helical scored heat pipes with synchronous vanishing, adiabatic and buildup wonder are contemplated utilizing Heat pipe test gear. In this hardware warmth pipe exposed to foreordain heat load an obstruction radiator at its evaporator end water coat with controlled progression water is utilized disperse warmth vitality at condenser end. Every one temperatures are estimated necessary computations are done get rate efficiencies at different stream rates warmth inputs. The exhibition warmth funnels correlation between their efficiencies is done. The sintered copper wick structure pipe have been found capable when stood out from other two with heat inputs beginning from 50 to 800 watts evaporator 30, condenser 72, adiabatic 110, flate heat pipe width 7.6mm, thickness 3.4 mm, first dia 6mm warmth pipe holder thickness in 0.5mm working liquid ethanol wick in view prevailing Capillarity property. The varieties of evaporator and condenser surface temperatures are plotted for changing warmth information sources and stream rate changes at condenser water coat. ANSYS programming is utilized for computational investigation and exploratory outcomes are in great concurrence with the examination.

Material properties for fracture mechanics based strength assessment of cast iron water mains

Municipal water distribution systems in Canada and other countries include a large number of cast iron pipes that were installed almost 50 years ago. For structural integrity assessment of these pipes, the fracture mechanics approach is found to be more effective than the conventional continuum mechanics-based approach. This paper presents the mechanical properties for fracture mechanics-based strength assessment of water mains determined through testing of cast iron pipes exhumed from two cities in Canada. Microstructure analysis is conducted to understand the materials’ inherent properties. Uniaxial tensile tests are conducted to determine the stress–strain relations. The influence of the rate of loading on stress–strain behaviour and loading-unloading responses are investigated. A simplified single-edge notch beam test is used to obtain the fracture toughness. Probabilistic distributions of the parameters are provided to account for the uncertainty and variabilities observed in the test results.

Experiment and numerical simulation of sand particle erosion under slug flow condition in a horizontal pipe bend

Sand erosion is a common problem in oil and gas field development. An experimental facility was designed and used to study the sand erosion of pipe bend under slug flow. A detachable test pipe bend was designed to measure the weight loss at 36 discrete locations on the pipe bend before and after each experiment. A Computational Fluid Dynamics (CFD) based erosion prediction method was developed to get a further understanding of the erosion. The relationships among the gas and liquid distribution, the sand movement and the erosion profile were analyzed to explain the erosion mechanism. The most severe erosion area of the pipe bend occurs at the axial angle of the elbow between 67.5° and 90° and at the circumferential angle of the elbow between 45° and 90°. The erosion profiles of the pipe wall are dominated by three particle collision mechanisms, namely, micro-cutting, plowing and impact deformation.

Ductile tearing simulation of STS410 pipe fracture test under load-controlled large-amplitude cyclic loading: Part I—Effect of load ratio

Ductile fracture of circumferential through-wall cracked pipe under large-amplitude load-controlled cyclic loading with three different load ratios was simulated using a fracture strain energy damage model. Damage model parameters were determined from a tensile test and a pipe test under monotonic loading. Comparison of simulated and experimental data reveals that the simulation results depend on the cyclic hardening model. Further investigation confirmed that selection of an appropriate cyclic hardening model is more important under load-controlled cyclic loading then under displacement-controlled one.

Experimental inquisition of heat pipe: performance evaluation for different fluids

ABSTRACT A comprehensive study for testing of cylindrical heat pipe has been carried out with a number of experiments. Characteristics and performance of heat pipe were evaluated individually with water, methanol, and acetone at different inclination angles (θ). Results obtained show that heat pipe charged with acetone has the smallest thermal resistance and highest heat transfer coefficient compared to other working fluids, hence identified as the best working fluid for the prepared heat pipes. Also, the best angle of inclination for the working heat pipe is 45° as the thermal performance of the heat pipe is optimal at this angle.

Comparative study of the explosion pressure characteristics of micro- and nano-sized coal dust and methane\u2013coal dust mixtures in a pipe

Coal dust explosion accidents often cause substantial property damage and casualties and frequently involve nano-sized coal dust. In order to study the impact of nano-sized coal on coal dust and methane–coal dust explosions, a pipe test apparatus was used to analyze the explosion pressure characteristics of five types of micro-nano particle dusts (800 nm, 1200 nm, 45 μm, 60 μm, and 75 μm) at five concentrations (100 g/m3, 250 g/m3, 500 g/m3, 750 g/m3, and 1000 g/m3). The explosion pressure characteristics were closely related to the coal dust particle size and concentration. The maximum explosion pressure, maximum rate of pressure rise, and deflagration index for nano-sized coal dust were larger than for its micro-sized counterpart, indicating that a nano-sized coal dust explosion is more dangerous. The highest deflagration index Kst for coal dust was 13.97 MPa/(m·s), indicating weak explosibility. When 7% methane was added to the air, the maximum deflagration index Kst for methane–coal dust was 42.62 MPa/(m·s), indicating very strong explosibility. This indicates that adding methane to the coal dust mixture substantially increased the hazard grade.

Optimizing Radiographic Sensitivity in the In-Service Testing of Pipes

In the in-service radiographic testing of water-filled pipes, the interaction of radiation with water diminishes the quality of the transmitted radiation to cause severe degradation in the radiographic sensitivity. In this paper, simulation work was carried out to investigate the radiographic testing of a water-filled pipe using X-ray and Ir-192 gamma source. The radiation reaching the film was studied, and accordingly, an approach to improve the radiographic sensitivity by optimizing the radiographic screen to control the scattered radiation was proposed. The approach showed promising indications, so the experimental work was proceeded using X-ray to validate the simulation results. The sensitivity, measured by the visibility of the Image Quality Indicator, was better in the radiographs obtained utilizing the proposed approach than that offered in the test used the standard screens.

Maintainability and reliability of high density polyethylene pipes through experimental and theoretical models

Our aim is to assess HDPE pipes’ degradation through the failure and reliability modelling by referring only to static tests and models instead of tedious and very costly dynamic ones. For that reason, we were interested in two kinds of specimens, standard ones for tensile test characterization and pipe ones for burst test purpose. The study was conducted over old and newly produced pipes specimens with multilevel notches. Indeed, the specimens were prepared according to the ASTM D 638 and ASTM 1599 respectively. Thus, we were able to establish four concepts of damage models based on the stress, the strain and the energy parameters, to quantify the ageing degradation effect on old pipes, and the burst pressure one, for the notched pipes. Therefore, the obtained results were compared considering neat, old and notched specimens for both the two tests. Then, we showed that the damage is somewhat symmetric around the critical life fraction of 52%. Besides, we concluded that the maintenance of the pipes become obligatory when we get over this point. In addition, the cross-discussion of damage-reliability curves allowed us to assess the limits of the HDPE pipes’ mechanical behavior. Thus, the irregularity of the damage through the wall of the old pipes allowed us to quantify and predict the consumed lifetime of them. These proposed simplified approaches have the advantage to assess quickly the degradation and stability of the studied polymer and decide the right maintence policy regarding the damage-reliability behavior of the studied specimens.

Testing of manufacturability of high-pressure pipelines for selective assembly

Technical characteristics of installations for testing pipes operating at high pressures of working media flowing through them are presented. It is shown that testing allows one to choose those pipes that provide their high reliability of operation at any maximum pressure and temperature differences before the start of the main line assembly. The created equipment is protected by patents and has operational advantages: scientific-based level of automation, long service life. This allowed to reduce the number of maintenance personnel, which is especially important in the conditions of fuel transportation through the Northern regions. New designs of devices to ensure reliable operation of seals in pipelines operating at large temperature differences in the ranges from cryogenic media to high heating in the combustion zone is created.

Simulation of overburden pressure during laboratory investigations of axial pipe-soil interaction

The simulation of additional soil overburden pressure through the use of a surcharge system is a technique commonly adopted in laboratory testing of pipe–soil interaction. This paper examines the i...

Calcium Carbonate (CaCO3) Scale Formation in A Piping System With Laminar Flow With Varied Temperatures and Malic Acid (C4h6o5) As Additives

Scale formation is a frequent problem encountered in industrial piping system. The occurrence of the scale is due to a chemical reaction between the dissolved ions in water. Calcium carbonate (CaCO3) is one of the scale that is often found. Scaling will thicken the pipe walls and can affect the rate off low or heat transfer. Hence preventing to the growth of scales is necesary in pipe. In this study some experiments were conducted on the growth of the scale of calcium carbonate in a test pipes, by reacting solution of CaCl2 and Na2CO each with a Ca2+ concentration of 3500 ppm with a flow rate of 30ml/min and temperatures used were 25°, 30° and 40°C. Malicbacid(C4H6O5) was added to the solutionas additive with concentrations of 0, 3, and 5 ppm. Calcium carbonate crystals could be seen from the results omorphological studies conducted using Scanning Electron Microscopy (SEM). The SEM results indicate that at 25°C and without additives, the scale comprises of calcite and vaterite, whereas with the additive of 5 ppm malic acid, the scale is vaterite with the larger crystal size and there is also calcite, but phase of the vaterite is dominant. At 40°C and without additive the crystal of a aragonite resembles a pile of needles.

Non-Destructive Testing and Evaluation of Friction Stir Welded AA6063 Circularly Butted Pipes

Friction stir welding of pipes is gaining research interest as it delivers high performance weld joints when compared to fusion welding techniques. Mechanical testing of such welded pipes will yield only results about mechanical behaviour but cannot detect the defects. An attempt has been made in employing non-destructive techniques in analysing the defects in Aluminium Alloy 6063 pipe joint obtained using friction stir welding. Three different tool pin profiles have been used in this study. The non-destructive testing methods employed helped to show the variation in the quality of the welds achieved through the three different tool pin profiles. Dye penetrant testing has been used in assessing the surface defects where solvent removable penetrant SKL-SP1 has shown evident results. Radiographic testing has been used in assessing root side defects. Tool with taper cylindrical pin along with tool rotational speed of 2000 rpm and weld speed of 0.6 rpm has produced weld with minor defects based on liquid penetrant and radiographic test results. Also the capability of non-destructive techniques in analysing the defects produced through friction stir welding has also been evaluated and presented.

Performance and hydrodynamics analysis of a Toroid Wear Tester to predict erosion in slurry pipelines

Erosion analysis is crucial for the design, operation, and economic assessment of slurry pipelines. Since field-scale pipe tests are difficult to control, lab-scale experiments are frequently employed. However, these techniques produce hydrodynamic conditions dissimilar to pipe flow. The Toroid Wear Tester (TWT) is a lab-scale tester with several promising attributes, including hydrodynamics more similar to pipe flow than other wear testers. However, no detailed studies on TWT performance and hydrodynamics have been performed. This work evaluates the repeatability and parametric wear trends of a TWT, as well as the major differences between TWT and pipe-flow hydrodynamics. Different particle sizes (0.1–2 mm) were tested at varying speeds (1–3 m/s) and solids concentrations (5–30% by volume). Visualization experiments showed that only larger particle sizes or lower TWT speeds are suitable for generating sliding-bed-dominated erosion comparable to pipe flow. Visualizations are also used to obtain correction factors for the TWT data, showing that visualization is a critical component of TWT testing. In addition to previously observed particle–coupon contact time and particle degradation effects, normal load and coupon edge effects are identified as important. Despite these limitations, the TWT is a promising apparatus for ranking material wear resistance and, with careful interpretation, for making pipeline erosion predictions.

The visualized investigation on flow and heat transfer characteristics of flat-plate heat pipe with micro rectangular grooves

With the development of information technology, the heating power of data transmission equipment (mobile phones, notebook computers, data center processors, etc) continues to rise, and the high temperature failure has become a major cause of equipment damage. At present, the heat flux of high-power chips has reached 2 ´ 106 W/m2. Therefore, the traditional single-phase heat transfer is unable to meet the heat dissipation requirements of new data equipment, and more efficient heat exchange methods are urgently needed to ensure the normal operation of the equipment. As a highly efficient phase change heat transfer element, the thin plate grooved heat pipe is researched in the order of millimeters or even micrometers. Therefore, flat grooved heat pipes simultaneously satisfy the heat dissipation and packaging requirements of high power data transmission equipment, and thus have been extensively studied. In the present study, the phase change characteristics and heat transfer performance of flat-plate heat pipes with rectangular grooves were experimentally studied. Each micro heat pipe test section consisted of twenty parallel grooves with the same total length of 90 mm. The cross-sectional area of G-400 heat pipe and G-800 heat pipe were 400 μm ´ 400 μm and 800 μm ´ 800 μm, respectively. The evaporation section, adiabatic section and condensation section had the same size of 30 mm, and vapor space height was equal to 3.6 mm. The flat-plate was sealed on its upper face with transparent plate, and the phase change phenomenon in the grooves could be observed. A high speed camera was used to visualize the phase change phenomenon in evaporation and condensation regimes. The experiments were carried out with the same cooling water temperature of 30°C under the conditions comprising the heat power range of 18–90 W and filling ratio of 150%–400%, respectively. In order to systematically investigate the performance of flat heat pipes with different dimensions of micro grooves, the analysis was focused on the heat resistance and phase change phenomenon in evaporation section and condensation section. The results showed that the heat pipe with wide grooves was able to maintain stable heat transfer performance at higher heat power, while heat pipes with narrow grooves would dry out at lower heat power. The optimal liquid filling rate of G-400 heat pipe was 400%, and the optimal liquid filling ratio of G-800 heat pipe was 150%. Furthermore, the heat transfer in the evaporation section of flat heat pipe with narrow grooves was mainly dominated by liquid film evaporation. Comparatively, the heat transfer phenomenon in the evaporation section of a heat pipe with wide grooves was affected by the liquid filling ratio. The liquid film evaporation was the main solution at low liquid filling ratio, and continuous bubble behavior was visualized in high filling ratio. In addition, the phase change behaviors in the condensation section of rectangular-grooved flat heat pipe not only occured at the gas-liquid interface, but also had droplet condensation phenomenon on the top surface of the groove rib. The cycle of condensation consisted of three stages: Droplet growth, droplet coalescence, and droplet department.