Steel Absorber Research Articles

Thermal 3D model for Direct Solar Steam Generation under superheated conditions

Parabolic-trough collectors (PTC) solar systems are one of the most promising of a wide range of the available solar technologies. Continuous breakthroughs are being achieved. Mainly due to the considerable amount of solar PTC plants that are being under operation in different countries. Within this continuous improvement effort, Direct Steam Generation (DSG) has been under development. DSG will lead to cheaper systems, not only for electricity generation but for heat process requirements. Working with superheated steam as thermal fluid, implies thicker pipe walls. Current numerical models neglect the radial dimension. In this context, simulating DSG absorbers implies considering radial domain discretization. A single phase model has been developed in order to work the 3D temperature field out on the solid parts, including the glass cover. Vacuum annulus has been assumed between stainless steel absorber and the glass envelope. The thermal radiative interaction between those parts has been considered without constant temperature assumption over the glass envelope. Finally, unidimensional approximation has been applied to the fluid domain. The whole code has been developed from the elemental (PDEs) governing equations and has been implemented in Matlab®. The numerical model has been validated from experimental results. These results have been gathered from an experimental DSG test facility with parabolic-troughs.

The time structure of hadronic showers in highly granular calorimeters with tungsten and steel absorbers

The intrinsic time structure of hadronic showers influences the timing capability and the required integration time of hadronic calorimeters in particle physics experiments, and depends on the active medium and on the absorber of the calorimeter. With the CALICE T3B experiment, a setup of 15 small plastic scintillator tiles read out with Silicon Photomultipliers, the time structure of showers is measured on a statistical basis with high spatial and temporal resolution in sampling calorimeters with tungsten and steel absorbers. The results are compared to GEANT4 (version 9.4 patch 03) simulations with different hadronic physics models. These comparisons demonstrate the importance of using high precision treatment of low-energy neutrons for tungsten absorbers, while an overall good agreement between data and simulations for all considered models is observed for steel.

A Parametric Study on the Thermal Performance of Unglazed Solar Water Collectors with Their Colorbond Steel Absorber Plates Also Used as Roofs

In this paper, an innovative unglazed solar water collector with its colorbond steel absorber plate also serving as the roof is proposed. Two most common colorbond steel profiles used as roofs, namely the Lysaght BlueOrb colorbond steel with the cosine profile and the Spandek colorbond steel with a trapezoidal shaped profile, are selected as the absorber plates. A theoretical energy balance model is developed to conduct a detailed parametric study on the thermal performance of this innovative unglazed solar collector with both colorbond steel absorber plate profiles under various configuration and operating conditions. The results show that both types of collectors can achieve high thermal efficiency (˜70%) and can increase the water temperature by about 8 °C, indicating they are suitable for the domestic utilization in at least tropical and similar regions as well; The two types of collectors produce very close thermal performances; improved thermal performance can be achieved through optimizing a number of parameters such as using a selective coating for the absorber plate to enhance its optical properties, using slender collector configurations, and using a compromized mass flow rate to maintain a high efficiency and to attain the higher temperature outputs.

A Method for Measuring the Optical Efficiency of Evacuated Receivers

Evacuated receivers used with parabolic trough solar collectors can be characterized in terms of their heat loss and optical efficiency. The optical efficiency is the ratio of the energy collected to the incident solar radiation when operating at ambient temperature. If one restricts attention to the active portion of the absorber receiving incident sunlight, this is equal to the product of the transmittance of the glass cover (τ) and the absorptance of the absorber surface (α). This paper describes a new outdoor transient test method for measuring the optical efficiency. An aluminum tube is inserted into the center of the stainless steel absorber tube, and the annulus between the two tubes is filled with a measured mass of aluminum shot. The receiver is precooled and then exposed on an outdoor test rig to solar radiation. The slopes of the temperature versus time curves for the aluminum filler and the steel tube are taken during a period of steady solar radiation and near the point at which the average glass temperature is close to the average absorber temperature (i.e., when there is minimal heat loss from the absorber tube to ambient). The slopes are then used to determine the optical efficiency. This method has the advantage of using the actual solar spectrum and has an uncertainty of about ±3%, which can be improved upon if a reference receiver is used for comparison. When this method was applied to the active section of the receiver tube, measurements of an actual receiver tube yielded a τα that, to within experimental uncertainty, is consistent with the manufacturer's values of τ and α.

Effect of Diffrent Absorbing Materials on Th Performance of Basin Solar Still Under Libyan Climate Conditions

This experimental study deals with a single-basin solar still using various absorbing materials with and without black painting. Different types of absorbing materials with and without black painting were used to enhance the solar still productivity throughimprovement in absorptivity. Those materials are steel and aluminum with and without black painting and rubber. Two identical solar stills were manufactured using locally available materials. All the results were compared together to reach the best absorbing materials with and without painting that can be used for solar still. It was found that the rubber absorber has the highest water collection during the daytime, followed by the black painted steel absorber, then by black-painted aluminum absorber and steel without painting absorber. The average enhancement in the daily productivity was about 50% for the rubber absorber comparedwith the black painted aluminum absorber and about 43% for the rubber absorber compared with the black painted steel absorber.

Study of corrosion behaviour of A106 carbon steel absorber for CO2 removal in amine promoted hot potassium carbonate solution (Benfield solution)

The CO2 absorber is one of the largest pressure vessels in ammonia plants, which are suffering from severe corrosion problems worldwide. The aim of the present study is to examine the corrosion behaviour of A106 carbon steel absorber for CO2 removal in amine promoted hot potassium carbonate solution (Benfield solution). This study simulates CO2 removal unit in ammonia production process at Abu Qir Fertilizers and Chemical Industries Company (Alexandria, Egypt) and many other plants all over the world. A typical Benfield solution contains hot potassium carbonate K2CO3, potassium bicarbonate KHCO3, diethanol amine (DEA) as a promoter and potassium metavanadate KVO3 as corrosion inhibitor. The rate of galvanic corrosion of carbon steel absorber/stainless steel pall packings couple in Benfield solution was measured without adding the corrosion inhibitor KVO3 in order to measure the influence of corrosive solution. The corrosion rate was measured by weight loss technique in relation to different operating parameters such as solution velocity, solution temperature, %K2CO3, CO2 loading, %DEA and the effect of the presence of solution contaminants. In general, increasing solution velocity, solution temperature, %K2CO3, CO2 loading and the presence of solution contaminations increase the corrosion rate. However, the increase in %DEA in solution decreases the corrosion rate. The strong dependence of corrosion rate on both solution and gas velocities indicates the diffusion controlled nature of the corrosion process. In addition, estimation of activation energy revealed a value of 4·8 kcal mol−1. Surface morphology study depicted the presence of a porous solid film of corrosion products on carbon steel surface. It has been found that the liquid phase diffusion of bicarbonate to the steel solution interface is the rate determining step.

Improving ice productivity and performance for an activated carbon/methanol solar adsorption ice-maker

The paper addresses the factors that can improve the performance of an activated carbon/methanol intermittent solar adsorption ice marker. It optimizes the ice maker under Dhahran climate with the MATLAB program to improve the performance and to increase the ice production per day per square meter of the solar collector. The optimizing results show that 14.1kg of activated carbon NORIT RX3-Extra per m2 of solar collector, double glazing cover, thin stainless steel absorber tubes with selective coating, suitable monthly collector tilt angle and suitable time for starting the cycle improve the performance. Moreover, the system can produce from 5kg up to 13kg of ice per day per m2 of collector area with improved solar coefficients of performance (SCOP) of 0.12 and 0.24 in the hot and the cold days, respectively. The optimized solar refrigerator is of benefit to further application and producing ice in grid-off rural zones.

Validation of GEANT4 Monte Carlo models with a highly granular scintillator-steel hadron calorimeter

Calorimeters with a high granularity are a fundamental requirement of the Particle Flow paradigm. This paper focuses on the prototype of a hadron calorimeter with analog readout, consisting of thirty-eight scintillator layers alternating with steel absorber planes. The scintillator plates are finely segmented into tiles individually read out via Silicon Photomultipliers. The presented results are based on data collected with pion beams in the energy range from 8 GeV to 100 GeV. The fine segmentation of the sensitive layers and the high sampling frequency allow for an excellent reconstruction of the spatial development of hadronic showers. A comparison between data and Monte Carlo simulations is presented, concerning both the longitudinal and lateral development of hadronic showers and the global response of the calorimeter. The performance of several GEANT4 physics lists with respect to these observables is evaluated.

Cause rare de compression médullaire

The paper addresses the factors that can improve the performance of an activated carbon/methanol intermittent solar adsorption ice marker. It optimizes the ice maker under Dhahran climate with the MATLAB program to improve the performance and to increase the ice production per day per square meter of the solar collector. The optimizing results show that 14.1 kg of activated carbon NORIT RX3-Extra per m2 of solar collector, double glazing cover, thin stainless steel absorber tubes with selective coating, suitable monthly collector tilt angle and suitable time for starting the cycle improve the performance. Moreover, the system can produce from 5 kg up to 13 kg of ice per day per m2 of collector area with improved solar coefficients of performance (SCOP) of 0.12 and 0.24 in the hot and the cold days, respectively. The optimized solar refrigerator is of benefit to further application and producing ice in grid-off rural zones.

Status of the CALICE analog calorimeter technological prototypes

The CALICE collaboration is currently developing engineering prototypes of electromagnetic and hadronic calorimeters for a future linear collider detector. This detector is designed to be used in particle-flow based event reconstruction. In particular, the calorimeters are optimized for the individual reconstruction and separation of electromagnetic and hadronic showers. They are conceived as sampling calorimeters with tungsten and steel absorbers, respectively. Two electromagnetic calorimeters are being developed, one with silicon-based active layers and one based on scintillator strips that are read out by MPPCs, allowing highly granular readout. The analog hadron calorimeter is based on scintillating tiles that are also read out individually by silicon photomultipliers. The multi-channel, auto-triggered front-end chips are integrated into the active layers of the calorimeters and are designed for minimal power consumption (power pulsing). The goal of the construction of these prototypes is to demonstrate the feasibility of building and operating detectors with fully integrated front-end electronics. The concept and engineering status of these prototypes are reported here.

The Calorimeter Systems for the sPHENIX Experiment at RHIC

A major upgrade is being planned for the PHENIX experiment that will have greatly enhanced physics capabilities to measure jets in relativistic heavy ion collisions at RHIC, as well as in polarized proton interactions, and eventually electron ion collisions at an Electron Ion Collider. This upgrade, sPHENIX, will include two new calorimeter systems. One will be a hadronic calorimeter, which will be the first hadronic calorimeter ever used in an experiment at RHIC, and another will be a new compact electromagnetic calorimeter. Both calorimeters will cover a region of ±1.1 in pseudorapidity and 2π in phi. The hadron calorimeter will be based on scintillator plates interspersed between steel absorber plates and read out with wavelength shifting fibers. The electromagnetic calorimeter will be an accordion design that will utilize scintillating fibers embedded in a matrix consisting of tungsten plates, tungsten powder and epoxy. The readout for both calorimeters will use silicon photomultipliers. The overall design of these two calorimeter systems is described along with the R&D efforts currently being pursued to develop them along with their readout.

Analysis of thermal efficiency of a passive solar water heater

The analysis of thermal efficiency of a passive solar water heater is presented. The heater which has potential applications in agro-industries and homes, consisted of a single-glazed flat plate solar collector made up of an absorber plate and a transparent sheet of glass; water storage tanks and the stand. The absorber plate was made of mild steel which is a very good conductor of heat. Copper tube was used to form a loop on the mild steel absorber. Water in the loop is heated by the radiant energy trapped by the absorber. The system was tested experimentally under daytime load conditions at Nsukka, Nigeria, over the ambient temperature range of 21 to 31°C, and a daily global irradiation range of 8.3 to 17.4 MJ m-2. Peak temperature rise of the heated water was about 83°C, while the maximum daily average useful efficiency was about 42%. It was deduced that the system can be operated successfully for agro-industries and home applications. Key words: Solar, water, efficiency, temperature.

Hadronic Showers in a Highly Granular Imaging Calorimeter

Abstract The CALICE collaboration develops highly granular calorimeter prototypes to evaluate technologies for experiments at a future lepton collider. The analogue hadronic calorimeter prototype consists of steel absorber plates interleaved with 38 active plastic scintillator layers which are sub-divided into small tiles. In total 7608 tiles are read out individually via embedded Silicon Photomultipliers. The prototype is one of the first large scale applications of these novel and very promising miniature photodetectors. Since 2006, the calorimeter has been operated in combined test beam setups at DESY, CERN and FNAL. The high-resolution 3D image data with analogue energy information are used to study properties and composition of hadronic showers at a new level of detail. This helps to constrain hadronic shower models through comparisons with model calculations. The spatial shower development and the substructure of the showers, compared to a variety of different Geant 4 shower models including decompositions into individual shower components are presented. Aspects of the energy reconstruction of hadronic showers, such as Particle Flow, are discussed.

Construction of the DHCAL

Particle Flow Algorithms (PFAs) have been proposed as a method of improving the jet energy resolution of future colliding beam detectors. PFAs require calorimeters with high granularity to enable three-dimensional imaging of events. The Calorimeter for the Linear Collider Collaboration (CALICE) is developing and testing prototypes of such highly segmented calorimeters. In this context, a large prototype of a Digital Hadron Calorimeter (DHCAL) was developed and constructed by a group led by Argonne National Laboratory. The DHCAL consists of 52 layers, instrumented with Resistive Plate Chambers (RPCs) and interleaved with steel absorber plates. The RPCs are read out by 1 x 1 cm2 pads with a 1-bit resolution (digital readout). The DHCAL prototype has approximately 480,000 readout channels. This talk reports on the design, construction and commissioning of the DHCAL. The DHCAL was installed at the Fermilab Test Beam Facility in fall 2010 and data was collected through the summer 2011.

Solar absorber tube analysis: thermal simulation using CFD

Solar–thermal power plants are being deployed world-wide. These plants have traditionally used steel absorber pipes. Two types of fluids have been used in such ventures, synthetic aromatic fluid or water. Fluid flow in parabolic trough systems leads to instability in the tube due to the concentrated solar flux on only one-half of the absorber tube, resulting in temperature asymmetricity. The resulting stresses cause deflection and bending of the tube. This paper deals with direct steam systems and proposes incorporation of internal helical fins within the tube to reduce temperature variation. The fins provide an orderly distribution of flow from the ‘hot’ to the ‘cold’ side of the tube. A CFD simulation was carried out for three fin pitches, and an aluminium pipe without fins. The effect on heat transfer improvement and temperature asymmetry is presently reported. It is shown that the thermal gradient between the upper and lower temperature for the pipe without a helical fin (20 K) is considerably higher compared with the pipes with 100, 200 and 400 mm pitch helical fins, i.e. 10.8, 13, 14.9 K, respectively. Also, the thermal gradient for the aluminium pipe was also much lower when compared with the steel pipe. Copyright , Oxford University Press.

3D pin-by-pin power density profiles with high spatial resolution in the vicinity of a BWR control blade tip simulated with coupled neutronics/burn-up calculations

Pellet cladding interaction (PCI) as well as pellet cladding mechanical interaction (PCMI) are well-known fuel failures in light water reactors, especially in boiling water reactors (BWR). Whereas the thermo-mechanical processes of PCI effects have been intensively investigated in the last decades, only rare information is available on the role of neutron physics. However, each power transient is primary due to neutron physics effects and thus knowledge of the neutron physical background is mandatory to better understand the occurrence of PCI effects in BWRs. This paper will focus on a study of local power excursions in a typical BWR fuel assembly during control rod movements. Burn-up and energy deposition were simulated with high spatial granularity, especially in the vicinity of the control blade tip. It could be shown, that the design of the control blade plays a dominant role for the occurrence of local power peaks while instantaneously moving down the control rod. The main result is, that the largest power peak occurs at the interface between steel handle and absorber rods. A full width half maximum (FWHM) of ±2.5 cm was observed. This means, the local power excursion due to neutron physics phenomena involve approximately five pellets. With the VESTA code coupled MCNP(X)/ORIGEN2.2 calculations were performed with more than 3400 burn-up zones in order to take history effects into account.

Experimental validation of control rod related perturbations of moderator regions in an SCWR-like fuel lattice

Two different types of perturbations of an SCWR-like fuel lattice have been investigated experimentally in the central test zone of the PROTEUS zero-power research reactor at the Paul Scherrer Institute in Switzerland. In each case, a campaign of high-resolution gamma-ray spectroscopy measurements was carried out on 34 fuel pins of the test lattice. In the first case, the test lattice was perturbed by inserting aluminum rods into the four central moderator regions, while in the second case, the perturbation was affected using steel absorber rods (instead of aluminum). The derived reaction rates are the capture rate in 238U ( C 8) and the total fission rate ( F tot), as also the reaction rate ratio C 8/ F tot. Each of these has been mapped on the lattice and compared to calculated results from whole-reactor Monte Carlo simulations with MCNPX. Excellent agreement has been obtained, for both perturbed lattices, between the calculated and experimental distributions of C 8, F tot and C 8/ F tot. Considering that control rods in an SCWR assembly are foreseen to be inserted into the central moderator regions, these results may be considered as generic validation of Monte Carlo simulations for the two different types of lattice perturbations which inserted control rods imply, viz. moderator displacement and strong neutron absorption. In a second step, calculated C 8, F tot and C 8/ F tot distributions for the two perturbed lattices (as well as for the unperturbed lattice) have been compared, at assembly level, between MCNPX and the deterministic LWR lattice code CASMO-4E. In the case of the unperturbed lattice, as well as for the lattice with steel rods, the agreement between the codes is found to be within ∼1% for all pins and each reaction rate. However, for the lattice with aluminum rods, i.e. the case with mainly just moderator displacement involved, CASMO overestimates the reaction rates in the vicinity of the perturbations by up to 2–3%, when employing the standard input options. The reason for this discrepancy has been found to be the leakage treatment, which uses the fundamental-mode buckling applied in a homogenized sense across the lattice. In this way, global leakage gradients get averaged out over the entire assembly. The optional input card BZ2 for CASMO resolves this problem, and the codes then agree within 1% even for the aluminum case.

Tests of a Digital Hadron Calorimeter

In the context of developing a hadron calorimeter with extremely fine granularity for the application of Particle Flow Algorithms to the measurement of jet energies at a future lepton collider, we report on extensive tests of a small scale prototype calorimeter. The calorimeter contained up to 10 layers of Resistive Plate Chambers (RPCs) with 2560 1×1 cm2 readout pads, interleaved with steel absorber plates. The tests included both long-term Cosmic Ray data taking and measurements in particle beams, where the response to broadband muons and to pions and positrons with energies in the range of 1 – 16 GeV was established. Detailed measurements of the chambers efficiency as function of beam intensity have also been performed using 120 GeV protons at varying intensity. The data are compared to simulations based on GEANT4 and to analytical calculations of the rate limitations.

Technical developments at the KIT gyrotron test facility

Parasitic beam tunnel oscillations have been discovered on some of the series production gyrotrons for W7-X and also on the coaxial pre-prototype gyrotron for ITER. Solutions to remedy these problems have resulted in a modified beam tunnel design, technologically close to the existing beam tunnel. The new design has successfully been tested on both the coaxial and also the f-step-tunable gyrotrons and has subsequently been implemented on one of the W7-X series-production-tubes presently undergoing factory acceptance tests in Karlsruhe. The ECRH test loads at KIT are operated under normal atmospheric conditions. Several loads have eventually failed in 1 MW long pulse experiments and KIT has therefore started to design its own loads. The first KIT-load is based on a fixed conical mirror and an aluminum cylinder coated with a lossy material for increased absorption. The new load has so far successfully been used during the acceptance tests of two 1-MW CW gyrotrons. Nevertheless a new load based on pure (uncoated) stainless steel absorbers is being developed as a backup solution for the ongoing high priority gyrotron testing. A superconducting magnet capable of rapid field changes between 4.15 and 5.67 T for frequency step-tunable gyrotrons has been procured, has demonstrated a (static) field of 7.2 T and its capability of rapid field-changes.

Crystal-assisted beam extraction and collimation at the U-70 circular accelerator

New crystal devices—an array of bent strips and a fan-type reflector based on thin straight plates—have been used to study extraction and collimation of the beam circulating in the accelerator at energies of 50 and 1.3 GeV. It is shown that these devices allow high-efficiency beam steering in a wide energy range. For 50-GeV protons, the efficiency of beam extraction and collimation is ∼90%, which is the highest efficiency attained for this method to date. It has been observed that the use of different crystals causes the particle loss at the accelerator downstream of the absorber to decrease by a factor of 2–3 in comparison with the standard single-stage scheme of beam collimation by a steel absorber.