Copper Tube Research Articles

Effect of benzotriazole on the existing pits of copper tube in fire sprinkler system

In this paper, two leaking tubes were investigated among copper tubes injected with 200 and 400 ppm benzotriazole after 8 years of usage. The electrochemical tests were conducted in simulated pit-out and pit-in environments (i.e., regions outside and inside of the pit) to determine the effect of benzotriazole on the propagation of an existing pit. The electrochemical analysis results showed that 200 and 400 ppm benzotriazole exhibit relatively lower inhibition efficiency in an acidic simulated pit-in environment because of the difficulty of forming a protective film and the benzotriazole cationization.

Investigation of the Concentric Heat Pump with Improved Energy Performance

This paper investigates the energy characteristics of the concentric heat pump. The heat exchanger of the evaporator of the "pipe in pipe" type, through the inner copper tube of which the refrigerant circulates, and inside the outer pipe - the coolant, is placed in a spiral around the compressor, cooling it and at the same time absorbing the heat released by it. The new design improves technical and economic performance. Experimental results were carried out, which confirm the possibility of maintaining the compressor temperature (80-90°C), increasing the heat output and conversion coefficient (COP) by an average of 10-15%. The proposed technical solution makes it possible to improve the energy efficiency of the concentric heat pump due to the absorption of the excess heat from the evaporator in the general heat flow and to reduce the emissions of CO2.

Experimental study on the thermal performance of Type-C near dew point radiant cooling wall panel

The radiant cooling system is a highly promising cooling technology that offers significant development potential. This paper introduces an innovative aquifer-cooled radiant wall panel, comprising a box, an aluminium plate, copper tubes, and water. The inclusion of water in the box optimizes heat exchange between the copper tube and the aluminium plate, as well as promoting uniform surface temperatures throughout the radiant panel. Importantly, the installation of this radiant wall system does not compromise the height of the space, making it particularly advantageous for retrofitting buildings. Traditional radiant floor and ceiling systems often reduce the available height, potentially exceeding acceptable limits. Experimental tests have demonstrated remarkable results for the cooling capacity of the radiant cooling wall panel, with an increase of 19.5 % to 49.3 % per unit area compared to the graphite radiant cooling ceiling plate under identical test conditions. Furthermore, the maximum temperature difference observed on the panel surface during operation is less than 1.8 °C, highlighting the system's efficiency and reliability.

Investigation of Hybrid Wires Combining Superconductive MgB2 and Ultra-conductive Graphene/Cu sheath

In our study, hybrid wires with ultra-conductive Graphene/Copper(GCu) sheath and superconducting MgB2 core were produced and experimentally examined. Cu tubes with outer/inner diameters of 15/12 mm were first coated with multi-layered graphene by chemical vapour deposition (CVD) method. Then, the ultra-conductive G/Cu tubes were filled with Mg+2B powder and they were gradually drawn into wires with a diameter of 1.94 mm. According the analysis results, the graphene coating process was successfully completed and the hybrid wires were produced by achieving MgB2 superconducting phase formation after annealing at 650∘C for 1 h. In this study, a graphene-coated copper tube with a CVD process was used for the first time to manufacture a superconducting wire. The ampacity value of industrial G/Cu sample has been improved in hybrid wires about 75% despite Cu exposed to mechanical deformations throughout the wire production process after graphene coating.

МОДЕЛЮВАННЯ ЕЛЕКТРОТЕПЛОВИХ ПРОЦЕСІВ В УСТАНОВЦІ ІНДУКЦІЙНОЇ ТЕРМООБРОБКИ АЛЮМІНІЄВИХ ЗЛИВКІВ І ВИЗНАЧЕННЯ ШЛЯХІВ ПІДВИЩЕННЯ ЇЇ ЕФЕКТИВНОСТІ ПРИ ПРЕСУВАННІ КАТАНКИ ДЛЯ СИЛОВИХ КАБЕЛІВ

A computer mathematical model is presented for the study of electrothermal processes in the installation of induction heat treatment of cylindrical aluminum ingots during pressing of wire rod for the manufacture of aluminum wire for power cables. The model makes it possible to determine energetically and technologically appropriate electromagnetic and thermal modes of induction heat treatment of ingots at a given voltage on the inductor. The results of the study of a typical installation for heating aluminum blanks for the purpose of their subsequent gradient pressing using a single-phase single-layer cylindrical inductor made of a rectangular copper tube are presented. Temperature distributions along the length of the aluminum blanks, as well as in the cross-sections of the billets at the output of the inductor, were obtained. A slight difference in the calculated electromagnetic and thermal parameters from the similar parameters of the operating installation confirmed the adequacy of the developed model. Ways to increase the efficiency of the induction heating installation by optimizing the profile of the inductor turns are considered. The influence of the thickness of the wall of the copper tube of the inductor close to the workpiece on the efficiency of the installation was determined and it was shown that its optimal thickness is at the level of the depth of penetration of the electromagnetic field into the metal. The possibility of using a three-phase power supply of the inductor was also investigated and it was shown that in this case it is most appropriate to use a phase angle shift between voltages of 60 el. degree. References 10, tables 2, figures 7.

Quantifying heat losses from experimental setup and their effect on annular channel heat flux using CFD

An advanced experimental setup in the form of a double-pipe heat exchanger has been developed to investigate various flow and heat transfer regimes in an annular channel. The experimental setup is designed for heat transfer measurements and flow visualization in a transparent annular channel with temperature-controlled heating of the inner tube. It allows measurements in both, single-phase and two-phase (boiling) flow regimes. The transparent annular channel is connected at the front and rear end by specially designed inlet and outlet headers, which ensure a uniform velocity field of the coolant (primary fluid) in the annular channel. The heating water (secondary fluid) heats the inner tube made of copper, which contains unique turbulators positioned equidistantly. These are designed to enhance the heat transfer on the inner side of the copper tube and to accommodate the thermocouples measuring the surface temperature of the tube.The main purpose of this study is to assess as accurately as possible the influence of heat losses in the experimental setup on the heat fluxes in the transparent annular channel. Therefore, it is necessary to accurately estimate the heat losses at the inlet and outlet header, upstream and downstream of the annular section. To this end, a detailed three-dimensional conjugate heat transfer CFD model has been developed and validated with a series of single-phase measurements, including the measured temperatures in both headers and the temperature profile along the heated inner copper tube. The simulated velocity and temperature fields have been used to quantify the heat flux distribution in the experimental setup. This study clearly demonstrates that properly validated numerical simulations can provide missing experimental information and significantly improve the interpretation of complex experimental results.

Evaluation of strength and electrical conductivity of copper clad-AA6063 bimetallic composite wire after annealing treatment

This study investigates the manufacturing of copper-AA6063 aluminum alloy composite wire and the effect of microstructural changes and metal-metal interface after annealing at 300 °C at different times on the strength and electrical conductivity. For fabrication of the composite wire, first AA6063 aluminum alloy wire was inserted inside an OFHC copper tube with a diameter of 6 mm. Afterward, a composite wire was produced using a cold drawing process in thirteen steps to a diameter of 1.5 mm. The tensile and microhardness tests used for evaluation of the composite wire's mechanical properties. Also, the light and scanning electron microscopes (SEM) used for microstructural characterization. The results showed that forming a region with a strain gradient at interface has a determinative effect on the strength and ductility of composite wire. The composite wire without annealing showed the highest strength, 278 ± 7 MPa. The annealing treatment result in strength reduction and negligible change in the electrical conductivity. The composite wire after annealing treatment for 30 and 60 min showed the highest electrical conductivity, 83 ± 1%IACS, and the highest elongation, 45 ± 4%, respectively.

Condensation Heat Transfer Experiments of R410A and R32 in Horizontal Smooth and Enhanced Tubes

Abstract A horizontal smooth copper tube and two enhanced tubes (a dimpled tube and a diamond-shaped tube) with a length of 2 m and an outer diameter of 9.52 mm were studied in a two-phase condensation experiment using R410A and R32 as heat transfer working fluids. The condensation heat transfer performance of different heat transfer tubes at various mass fluxes ranging from 150 to 400 kg/(m2s) and different vapor qualities ranging from 0.8 to 0.2 was studied experimentally. For R410A, the heat transfer coefficients (HTCs) of the dimpled tube and the diamond-shaped tube were found to be 1.39–1.52 times and 1.30–1.35 times higher than those of the smooth tube, respectively. For R32, the HTCs were found to be 1.46–1.59 times higher for the dimpled tube and 1.26–1.35 times higher for the diamond-shaped tube than for the smooth tube. The diamond-shaped tube was found to be effective in directing the flow of the liquid phase and in thinning the liquid film thickness. The dimpled tube was found to promote droplet entrainment and disturbance. Both of those effects contributed to improving the HTCs in the two enhanced tubes investigated. The HTCs of R410A were found to be lower than those of R32 because of the smaller specific heat capacity, smaller latent heat of condensation, and relatively poorer thermal conductivity of R410A. Taking the combined effect of heat transfer and pressure drop into account, a performance enhancement factor (PEF) was computed and was found to range from 0.9 to 1.51. Based on the experimental data collected, a new empirical correlation equation has been proposed with a maximum error band of 10%. Flow pattern maps for the tested tubes have also been generated and are presented in the paper. Both of the two enhanced tubes were found to promote the development of annular flow. The HTCs were found to be highest when the flow pattern was of the annular flow type.

An Investigation into the Factors and Mechanisms Underlying Corrosion Failure of B10 Copper Tubes in Shipboard Pipelines

The present study investigated the corrosion behavior and mechanism of B10 copper tubes used for shipboard pipelines through various analytical techniques, including macroscopic inspection, chemical analysis, electrochemical impedance, corrosion product morphology, and physical phase and electron microscopic observation. The research findings revealed that the surface corrosion product film on the B10 copper tube in seawater mainly consists of Cu2O. Furthermore, the corrosion behavior under actual working conditions was attributed to crevice corrosion, non-electric coupling corrosion, and the corrosion mechanism was found to be the result of the combined effect of oxygen concentration difference cell and occlusion cell autocatalytic effect. These observations provide valuable insights into the corrosion performance of B10 copper tubes in seawater, which could potentially aid in improving their durability and reliability in marine applications.

Thermal response of an asphalt solar collector: Numerical and experimental validation

This study conducts a numerical analysis and experimental validation of the thermal performance of an asphalt solar collector. Both parallel and serpentine copper tubes with a total length of 3000 mm were embedded in the middle of a 1000 × 600 × 80 mm hot mix asphalt model. The sides and bottom of the test sections were insulated to prevent heat loss to the surrounding environment. Using four values of water mass flow rate and three values of artificial solar radiation, the thermal performance of the system was examined. A mass flow inlet of 0.0038–0.035 kg/s is specified for the water inside the embedded tubes, while 600, 800, and 1000 W/m2 solar radiation is applied on the upper section of the asphalt mix during this study. The thermal response was simulated using the COMSOL Multiphysics 5.6.0.280 heat transfer module. Using a reference asphalt solar collector, the desired parameter effects were investigated independently. The experimental results showed that the efficiencies of the asphalt solar collector with serpentine bare tubes and parallel bare tubes are 53.56 % and 52.85 %, respectively. The numerical simulation reveals that there is no significant thermal effect in the area under the embedded tubes when compared to the area above the tubes that are exposed to solar radiation from above. The average error found between the numerical and experimental results for the water temperature difference inside the embedded tubes of the asphalt solar collector ranged between 6 % and 14 %. This good agreement indicated that the computational fluid dynamics model is reliable and capable of simulating the thermal response of an asphalt solar collector.

Performance analysis of evacuated tubes with thermosyphon heat pipe solar collector integrated with compound parabolic concentrator under different operating conditions

The present work experimentally evaluated the performance of a solar collector comprised evacuated tube heat pipe (ETHP) coupled with a compound parabolic concentrator at different tilt angles. Therefore, experiments have been conducted in the climate conditions of Tamil Nadu (77.07° E,11.04° N), India, from April 15, 2019, to May 20, 2019. The objective of the work is to explore the effect of a tilting angle on the performance of an evacuated tube solar collector with a thermosyphon attached to the compound parabolic concentrator. The CPC is designed with an aperture width of 343 mm, concentration ratio of 2.32, and aperture angle of 25.4°, improving the solar collector efficiency with the help of MATLAB Programming, which gets Coordinate points based on these coordinate points. CPC Profile is fabricated. The Thermosyphon heat pipe is constructed with a Copper tube having a 19 mm diameter with 40% Acetone charged. The experiments were conducted by varying the tilting angles of the solar collector at 15°, 30°, 45°, and 60° horizontal. The heat resistance and instantaneous efficiency of the solar collector are studied in this study. The result reveals a minimum thermal resistance of 0.02 kW−1, and a maximum efficiency of 78% was recorded at a 45° tilting angle.

Experimental and numerical study of desalination using solar energy and phase change materials

The present work experimentally desalinate water and model a passive solar desalinator of 0.55 m2 that uses phase change materials (PCM), assessing the effects of storing energy in 4.5 kg of coconut oil or paraffin wax contained in copper tubes, and the mass of water in the container (5.55, 8.25 and 11.0 kg), on the unit performance. The experiments carried out in Santiago de Chile allowed to obtain condensate masses between 3.2 and 4.3 kg/m2 per batch with a temperatures between 23 and 83∘C for the absorber plate and 21–77∘C for the glass. Annual water production ranged from 1120 to 1313 liter/m2, with costs between 0.0165 and 0.0593 $/liter. PCM incorporation had no impact on production as the exposed area is shared between absorber plate and tubes. To better evaluate the effect of the parameters studied, results are presented as the ratio between the mass of condensate and the solar energy received, which gives independence from the solar irradiation variability and allowed to identify a slight superiority in the productivity of condensate using coconut oil. The model developed and coded in MATLAB, including PCM and the effect of self-shading, adequately predicts the mass of condensate and phase temperatures (water, glass and PCM) with a mean root mean square error of 0.03 kg and 1.9∘C respectively. The model is characterized by a low computation time and a high level of prediction for the condensate mass.

High temperature superconducting CORC cable with variable winding angles for low AC loss and high current carrying SMES system

Owing to the rising demand for enhanced high-current capacity within superconducting magnetic energy storage (SMES) system used in power grids, there is a growing focus on enhancing the current-carrying capability of SMES setups wound with conductor on round core (CORC) cables. However, it is crucial to note that the dissipation of AC losses in CORC cables during rapid charge and discharge cycles can substantially impact the safe operation of SMES. The CORC cable is crafted by spirally winding numerous ReBCO tapes around copper tubes. Even slight alterations in the winding angles of these tapes can result in shifts at current distribution across the ReBCO tapes, thus leading to differences in AC losses. Hence, the primary objective of this paper is to study the effect of varying winding angles of each ReBCO layer on AC loss. The adoption of variable angles results in the reduction of current flowing through the outermost tapes. And the AC losses in the outermost tapes happen to account for the majority of the total AC losses. Through simulations and experiments, it was observed that the AC loss in the CORC cable with variable angles (4 × 12, 25°–40°) was 25% lower than that in the case of fixed angles (3 × 11, 45°). These findings demonstrate a noteworthy downward trajectory in AC losses when variable angles are applied to the CORC cable. These insights hold significant value for the practical application of CORC cables within SMES systems.

Condensation heat transfer and pressure drop of low-global warming potential refrigerants in smooth aluminum tubes

In this work we report condensation heat transfer coefficient and pressure drop data for R-454B, R-32, and R-454C. These refrigerants are low Global Warming Potential (GWP) replacements for R-410A. We obtained these data in a smooth 7.2 mm outer diameter (5.94 mm inner diameter) aluminum tube. In these experiments, the key variables were condensation temperature (35 °C ≤Tcond≤50 °C) and refrigerant mass flux (151.1≤G≤347.3 kg m−2 s−1). In general, for similar nominal operating conditions, we measured the highest heat transfer coefficients for R-32 and the lowest for R-454C. Among the correlations we used to predict the heat transfer data for all three refrigerants, the one developed by Thome et al. (2003) predicted the data with the greatest accuracy. Deviations between experimental data and predictions of this correlation were 21.7% for R-454B (with SBG correction), 22.0% for R-32, and 18.8% for R-454C (with SBG correction). Experimental pressure gradient data were predicted by the Friedel correlation Friedel (1979) with deviations of 13.8% for R-454B, 9.8% for R-32, and 10.2% for R-454C. In this work, we also compare the predictions of the Cavallini et al. correlation Cavallini et al. (2006) for R-454B and R-32 in smooth copper versus smooth aluminum tubes. To improve this correlation’s predictive capability for aluminum tubes, we have proposed some modifications. After incorporating these modifications, the deviations between the correlation’s predictions and our data were 10% for R-454B (with SBG correction), 8.1% for R-32, and 5.2% for R-454C (with SBG correction). These data and findings will assist the HVAC and refrigeration industry to implement low-GWP refrigerants in condensers using smooth aluminum tubes.

Electrodeposited histidine-(CuCr)layered double hydroxides/carbon dots for in-tube solid-phase microextraction of chlorophenols from water, juice, and honey samples followed by HPLC-UV

A novel adsorbent consisting of a composition of carbon dots and CuCr-layered double hydroxides intercalated with l-histidine (C-dots@His/LDHs) was introduced. This adsorbent was electrochemically deposited on the inner surface of a capillary copper tube. It was used as an adsorbent for in-tube solid-phase microextraction of chlorophenols (CPs). Separation and measurement of CPs were done by high-performance liquid chromatography-ultraviolet detector. The main parameters which had the most impact on the extraction efficiency and time such as extraction time and flow rate, desorption time and flow rate, ionic strength (salt concentration) and pH were optimized. Calibration curves (0.5–1000 μg L−1) were plotted in real sample (tap water) under optimal conditions which coefficients of determination better than 0.9893 and relative recoveries in the range of 88–120 % were obtained. The limits of detection (S/N = 3) and limits of quantification (S/N = 10) were obtained in the range of 0.1–1.0 μg L−1 and 0.3–3.0 μg L−1, respectively. The intra- and inter-assay precisions (RSD%, n = 3) were better than 5.9 and 8.8 %, respectively.

Film Deposition Behavior of Phosphorus Copper Tubes during Stress Corrosion Cracking

Film Deposition Behavior of Phosphorus Copper Tubes during Stress Corrosion Cracking

Design and performance evaluation of pulsating heat pipe using metallic nanoparticles based hybrid nanofluids

Pulsating heat pipes (PHP) use two-phase flows to transport heat between evaporators and condensers. The performance of PHP largely depends on the thermal conductivity of the working fluid. The research objective of this study is to investigate PHP performance enhancement with HNF consisting of metallic and metallic oxide nanoparticles and compare the PHP performance with different working fluids. A three-turn PHP made from copper tubing was fabricated and charged with Al2O3-Cu HNF, Al2O3 mono nanofluid, Cu mono nanofluid, and pure water for performance evaluation. A total of ninety-eight (98) experiments were conducted with four working fluids over a range of operating conditions, including nanoparticles weight concentration (0.1 % and 0.2 %), filling ratio (50 % and 60 %) and heat input (30–90 W). Results showed that the Al2O3-Cu HNF achieved 30–54 % lower thermal resistance than water, and 17–43 % lower than the mono nanofluids at the same filling ratio, weight concentration and heat input, which indicates superior heat transfer enhancement. The optimal condition for the PHP filled with Al2O3-Cu HNF examined in this study was achieved at a 60 % filling ratio and a 0.2 % weight concentration of nanoparticles. However, maintaining the stability of Al2O3-Cu HNF poses challenges due to the hydrophobic nature of Cu nanoparticles. Future studies are planned to use molecular dynamics simulation to investigate factors influencing the stability of metallic nanoparticles-based mono and hybrid nanofluids.

Heat transfer of uncoated and nanostructure coated commercially micro-enhanced refrigeration tubes under pool boiling conditions

The heat transfer performance of commercially produced micro-enhanced tubes with and without a nanocoating was investigated under pool boiling of saturated refrigerant. These multiscale enhancements were on the outside of 19 mm horizontal copper tubes heated by water to determine the effectiveness of this multiscale enhancement technique on industrially relevant tubes and geometry. The tubes tested were a plain tube roughened by sandpaper, a low finned GEWA-KS tube and two micro-enhanced re-entrant cavity tubes, the GEWA-B5 and EHPII. The tubes were tested in R134a at saturation temperatures of 5 °C and 25 °C across a range of heat fluxes from 20 kW/m2 to 100 kW/m2 under pool boiling conditions. The nanocoating applied to the tubes produced a forest of copper oxide nanostructures on the surface, increasing wickability of the surface. A Scanning Electron Microscopy showed that copper oxide nanocoatings coated all micro-enhanced tubes evenly without impeding the surface features or significantly blocking the re-entrant cavities. For the uncoated tubes in pool boiling, the heat transfer coefficients of the EHPII was up to 519 % greater than those of the plain roughened tube, the GEWA-B5 was up to 539 % higher than the roughened tube and the GEWA-KS was at best 64 % higher than those of the plain roughened tube. Increases in the saturation temperature to 25 °C produced minor improvements in heat transfer coefficients. The application of the copper oxide nanocoating resulted in generally decreased heat transfer performance by approximately 40 % on average compared to the uncoated tubes, with the GEWA-B5 tube the worst affected. Degradation of the heat transfer is thought on plain surfaces to be due to the flooding of nucleation sites, while re-entrant cavity style enhanced surfaces were thought to experience degraded sensible and latent heat transfer due to impeded flow in the microstructure capillary channel, as bubbles were noted to be trapped in the channels. It is recommended that the heat transfer at much higher heat flux ranges be explored for possible HTC enhancement.

Experimental studies on the enhancement in discharging characteristics of phase change material with steatite nanoparticles

Phase change materials are latent heat energy storage systems that can store huge quantities of thermal energy in a small volume. Latent heat energy storage systems are complicated to design due to the low thermal conductivity of phase change materials for discharging to enhance the heat capacity and latent heat storage. The objective of the study is to examine the discharging of phase change material in a latent heat energy storage system for maintaining the temperature of the water. Paraffin wax utilized as the phase change material due to its higher latent heat capacity. The experiments were performed with the flow of the hot water through a phase change material container by using a copper tube to enhance the discharging of phase change material during solidification to maintain the temperature of the water. Furthermore, the steatite nanoparticle has been dispersed with phase change material to enhance the discharging of characteristics. The steatite nanoparticle has been selected due to its low thermal conductivity, and the weight percentages nanoparticles were varied viz. 10 %, 20 %, 30 %, and 40 %. The increase in water temperature from 0.1 °C to 1 °C has been taken 7 h by enhancing the discharging of phase change material with various concentrations of the steatite nanoparticle. The work shows the significant discharging characteristics of phase change material with steatite nanoparticles. The nano-phase change material has the potential to maintain the temperature of water without any external energy for a particular duration, which shows cost-effectiveness.

Superconducting shield for the injection channel of the muEDM experiment at PSI

At the Paul Scherrer Institute (PSI), we are setting up an experiment to search for the electric dipole moment (EDM) of the muon using the frozen-spin technique. The discovery of a muon EDM would indicate violation of charge conjugation parity symmetry (CP-violation) and lepton flavor universality, beyond the Standard Model. The experiment aims to achieve a sensitivity of σ(dμ ) ≤ 6 × 10-23 e · cm.This study is taking place during the first phase of the experiment and it focuses on the off-axis injection of muons into a 3 T storage solenoid. Muons need to be transported from the exit of the PSI beamline, a low magnetic-field region, into the strong magnetic-field of the solenoid. For this purpose, two magnetically shielded channels are being developed. In the direct vicinity of the injection helix inside the solenoid bore, we will use superconducting (SC) shielding to avoid any hysteresis effect, while farther away in the fringe field we will use iron tubes. Three prototypes of SC injection tubes will be produced: the first will use a commercial high temperature superconducting (HTS) tape wrapped around a hollow copper tube, the second will utilize several Nb-Ti/Nb/Cu sheets obtained from CERN, wrapped and mechanically clamped around another hollow copper tube, while the third will consist of a commercial cast Bi-2223 superconducting tube coiled with HTS tape. To evaluate the effectiveness of the different SC-shields, we will measure their shielding factors and determine the muon injection efficiency from the beamline into the solenoid.