Side Piping Research Articles

Evaluation and machine learning prediction on thermal performance of energy walls in underground spaces as part of ground source heat pump systems

Energy walls (i.e. wall heat exchangers) exhibit more complex thermal performance than do energy piles and borehole heat exchangers in ground source heat pump systems, due to their individual geometry. This study conducted field tests of energy wall thermal performance to analyze the influence and interaction of the pipe burial depth, flow rate, heating load, and operation mode. To evaluate the energy wall thermal performance in multiple dimensions, three novel evaluation indices (energy utilization ratio, thermal saturation, and effectiveness) were defined. A thermal performance SVR prediction model of an energy wall was established based on 227 field-measured samples. The heat exchange power, energy utilization ratio, and effectiveness of the ground side pipe are approximately 15%, 8% and 64% greater than those of the excavated side pipe, respectively. Considering the interaction between the flow rate and heating load, blindly increasing the heating load is not the most effective way to improve the thermal performance. The influences of heating loads and operation modes on heat exchange power differs from that on the energy utility ratio and both side’s thermal saturations, indicating that there is a complex interaction between the heating loads and operation modes. The cross-verification and prediction results show that the optimized thermal performance of the SVR model exhibited satisfactory generalizability and prediction performance.

Mixing hydrogen into natural gas distribution pipeline system through Tee junctions

Hydrogen injection into natural gas distribution pipeline system through Tee junctions is numerically studied, by considering both ideal and Soave–Redlich–Kwong real gas models. The mixing homogeneity length is quantified for various side pipe sizes and perpendicular configurations for distribution-pressure and intermediate-pressure pipelines. The buoyant nature of hydrogen once blended into natural gas pipelines introduces a challenge as it tends to stratify and become trapped near the top wall.Accordingly, a greater side flow momentum leads to a shorter mixing homogeneity length. This reduces up to three to five times particularly when it penetrates deeply into the main flow without getting trapped from the beginning. Consequently, vertical bottom-side injection yields a mixing homogeneity length that is roughly four times shorter than horizontal and five times shorter than vertical top-side injection. Furthermore, employing a real gas model is critical once the pressure rises to intermediate pressures, resulting in a greater homogeneity length.

Local Resistance Characteristics of T-Type Tee Based on Chamfering Treatment

The T-type tee is a crucial part of liquid distribution systems and is widely used in irrigation, drainage, water delivery, and agricultural fertilizer injection, among other areas. Confluence angle, pipe diameter ratio, and flow rate ratio have been the main focus of previous research. Research on the hydraulic characteristics and resistance optimization brought about by the main-side pipe intersection’s chamfering treatment is, nevertheless, incredibly rare. Optimizing the structure of the T-type tee could improve its sustainability in many aspects, such as its energy consumption, durability, and production process. In order to fill this void in the literature, the current investigation concentrated on the resistance reduction and flow properties of T-type tees by means of chamfering treatment. Using a newly proposed coefficient called the integrated local resistance coefficient, the integral flow characteristics and resistance reduction effects of T-type tees were addressed. Through the use of the verified computational fluid dynamics (CFD) method, the crossed effects of five chamfer ratios (R = 0D, 0.5D, 1D, 2D, and 3D), nine flow rate ratios (0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, and 0.9), and two pipe diameter ratios were examined. When the Reynolds number exceeded 3 × 105, the flow remained in the quadratic drag region, meaning that the local resistance coefficient of T-type tees was no longer dependent on the flow velocity. In both confluence and shunt conditions for equal tees, chamfering treatment was proven to be an efficient method for reducing local resistance under these conditions. For instance, following a 1D chamfering treatment on the T-type confluence tee, at a flow ratio of 0.5, the local resistance coefficients ζ1 and ζ2 dropped by 68% and 82%, respectively, in comparison to the 0D condition. The effects of resistance reduction were improved by a wider chamfer radius and a higher side pipe flow rate ratio. The highest overall performance was obtained by chamfering a T-type tee with a curvature radius of 1D, taking into account flow characteristics, sustainability, processing technology, economic cost, and promotion difficulties. The chamfering procedure produced a more noticeable reduction in resistance for unequal tees with comparable velocities in the main and side pipes when the pipe diameter ratio was greater than 0.5.

An intelligent control and regulation strategy aiming at building level heating balance in district heating system

In district heating system (DHS), hydraulic imbalance has hindered further energy saving, which results in high energy consumption and meaningless heat loss. This issue is particularly serious in the building side whose scale and structure are more complex than that of heat exchange station (HES) side. Focusing on the building side balance, this paper proposed a building level intelligent balancing system and corresponding control strategy. The balancing system featuring smart valves installed at the building entrance, adjust the valves opening according to target return temperature to accommodate the heat distribution among buildings. A dynamic calculation model coupling a linear correction is established to decide the target return temperature of each smart valves considering buildings’ thermal characteristics. The proposed intelligent balance system is applied to a practical district heating system. The unregulated indoor temperature ranges from 20.9 °C–25.2 °C, while a smaller range of 22.6–24.0 °C after regulation. The results indicated that the hydraulic and thermal imbalance among buildings were significantly improved with regulation. Moreover, the heat consumption index was reduced and an energy saving rate of 3.73% was achieved. This study provides a reference for similar building side pipe network balance regulation.

A Compressible, Coupled Three-Dimensional/One-Dimensional Flow Solution Method for the Seamless Simulation of Centrifugal Pumps and Their Piping

Abstract A compressible finite volume Navier–Stokes flow solver is coupled to a method of characteristics for the seamless turbulent flow simulation of entire pump systems. For the pump, three-dimensional (3D) simulations including cavitating flow conditions are performed, and the piping is treated one-dimensional (1D) by a method of characteristics. Thus, classical boundary conditions at the suction and pressure pipe of the 3D computational domain of the pump are substituted by a two-way coupled 1D piping simulation method. Particular emphasis has been placed on the non-reflecting properties of the 3D–1D coupling interface. For validation, in-house experiments are performed on a low specific speed centrifugal pump in a closed-loop facility. For cavitating flow conditions, excitation on the pump's pressure side by rotor–stator interaction is enhanced over a broad frequency spectrum due to collapsing voids. The suction side piping is shielded by void regions within the blading from the excitation on the pump's pressure side, leading to an acoustic decoupling of the suction side. These experimental observations are reproduced by the new seamless simulation method. In particular, the measured pressure amplitudes are well reproduced for a broad frequency spectrum, at several piping positions, and for a variation of the flow rate and the cavitation intensity. Remaining deviations to experimental data are traced back to the omission of structural compliance and uncertainties regarding the pressure side piping modeling, which will be addressed in future studies.

CFD study on the effect of nanofluids in natural circulation loop

A vertically placed natural circulation loop consists of a heater in the riser pipe and a heat exchanger at the top end for heating and cooling the working fluid. In this investigation, the heat source is placed in the side pipe of the loop called riser. The performance of natural circulation loop is investigated with water, Alumina nanofluid and Copper Oxide (CuO) nanofluid of 0.5%, 1% and 1.5% (by wt) concentration. The behaviour of the loop for various heat inputs at the heat source is investigated with water and then with Alumina and CuO nanofluids.It is found that the performance of the loop is high when the working fluid used is copper oxide nanofluid compared to alumina nanofluid and water. The mass flow rate is highest for 1.5% CuO nanofluid which is 4.58 g/s. Heat transfer coefficient of the loop fluid at the heat source increases with an increase in the heat input at the heat source. There is also a significant difference for heat transfer coefficients of water and the nanofluids of CuO and alumina in the natural circulation loop for various amounts of heat supplied in the heat source.

Experimental Study of Heat Transfer Enhancement by Turbulence Generator in Side Pipe

The enhancement of heat transfer exchangers is an important matter of concern for achieving more efficient thermal energy conversion systems. The use of modified twisted tape (TT) inserts as a passive heat transfer augmentation technique is an efficient way of improving heat transfer. Twisted tape insert is one of the passive heat transfer enhancement techniques that are widely used in various applications for heat transfer, such as air conditioning and cooling systems, heat recovery systems, Processes, procedures for food and milk, plants for chemical processes. To increase the heat transfer rate of the tubular heat exchanger, in this study a small-scale experimental setup was performed. The heat improvement of the heat exchanger is done using twisted tape inserts with a twist ratio (y=5.5). The effects of two-dimensional parameters namely Nusselt number & friction factor on tubular heat exchanger effectiveness are studied. The turbulent flow was generated by the insertion into the test pipe of the twisted tape inserts, producing a high turbulence rate in the pipe, resulting in an increase in turbulence. And hence the enhancement of heat transfer and drop in pressure. The length and width of the insert were 1000 mm and 21.5 mm respectively. The diameter of the test pipe outside & inside is 23 mm and 22 mm respectively. The length of the test section is 2000 mm. The study is carried out for the Reynold number regime (500-6500). The results show that The maximum enhancement for Nu number at Re 500 was 32% that of the plain tube.

Development of an Electrolytic Pilot Plant for the Production of Chlorine Gas “In Situ” in the Disinfecting Water Process

Technology of gaseous chlorine in water treatment has shifted to the dosage of sodium hypochlorite or calcium hypochlorite because of their greater biocide power; require less contact time with the microorganisms in the pretreated water, and the pH of slightly affect water. The generation of chlorine gas in place is based on the principles of electrolytic dissociation and laws of electrolysis by Faraday. The equipment corresponds to an electrolytic cell of three (3) compartments , a central one (anode) where chlorine gas emerges , and two side (cathodes) where sodium hydroxide is produced in the central compartment must be refilled chloride solution sodium consumed due to the electrochemical reaction , the chlorine evolved being of gaseous nature ascends the column of sodium chloride and is captured by the vacuum venture system , who to put in direct contact with target that has been previously subjected to the processes of uptake , coagulation , sedimentation and filtration. Compartments anode-cathode - anode are physically separated by porous diaphragm, whose purpose is to permit selective flow of sodium and chloride ions , avoiding side reactions recombination , as additional product is the formation of sodium hydroxide in the cathode chambers, which should be removed from the cell through side pipes. Statistical models were used to optimize the performance and operation of the prototype.

ANALISA NPSH KERUSAKAN IMPELLER POMPA CETRIFUGAL CAIRAN CH3OH

Liquid behavior is always influenced by the environment in the form of temperature and pressure (thermodynamics). This temperature and pressure affect the nature of the change in liquid phase into a mixture of water and steam or vice versa. Pumps that function to drain liquid also have temperature and pressure. If the pressure drops and the temperature stays or rises at the pump, the liquid phase changes to a liquid and vapor mixture phase. This phase change in the pump (suction side) is called the phenomenon capitation. Capitation in the pump will cause erosion of the impellers parts, resulting in decreased performance. This study analyzes the erosion of the casing and impeller at the 040-G01S pump of PT. KMI from the point of phenomenon of capitation. The phenomenon of capitation in pump suction empirically can be known if the required NPSHa value is less or equal to the available NPSHr value or NPSHa ≦ NPSHr. The NPSHa value is affected by the suction pump installation configuration. To find out the cause of erosion on the casing and impeller, it is necessary to calculate the NPSH (Net Positive Section Head) required and those available (manufacturers). The results of this study NPSHa value = 4.75 m and NPSHr value = 5 m) or NPSHa ≦ NPSHr at tank level <45%. So it is necessary to modify the installation of the pump suction side piping.

Coupled convection heat transfer of water in a double pipe heat exchanger at supercritical pressures: An experimental research

An experiment about coupled convection heat transfer of water in a double pipe heat exchanger at supercritical pressure was conducted. The effects of experimental variables on the heat transfer were investigated, and the buoyancy effect on the heat transfer of the outer pipe was analyzed emphatically. There is a difference between the peak heat transfer coefficient temperature and the pseudo-critical temperature, and the difference increases with the increase of pressure. This phenomenon is caused by the temperature gradient and the variations of thermal-physical properties in the heat transfer section. The mass flow rates of the inner pipe side and outer pipe side were always equal, and one side will offset the effect of the other side on the heat transfer. The heat transfer coefficient of the outer pipe increases with the increase of water temperature at the inlet of the inner pipe when the mean bulk temperature is lower than the pseudo-critical temperature, due to the buoyancy effect decreases at the same time. While, the buoyancy effect is almost independent of the water temperature at the inlet of the inner pipe when the mean bulk temperature is higher than the pseudo-critical temperature, due to the buoyancy effect is non-significant. A new heat transfer empirical correlation was proposed, which includes 94.01% of experimental data are within ±25% error bars.

شبیهسازی انرژی و تحلیل پارامتری سیستم فتوولتائیک حرارتی آب خنک

In this paper computerized simulation of water-cooled photovoltaic/thermal system has been investigated. The configuration of the selected system was a plate and spiral tube type. Energy simulation was done through code development in MATLAB software. The proposed model has been validated with practical data. Thereafter, overall performance of the system has been evaluated. Afterwards, parametric analysis was done in order to compare the effect of the variation of operational parameters on thermal and electrical energy efficiencies. To cover this aim, variation of overall efficiency and pressure drop have been investigated versus variation of water flow rate and the distance between tubes as well as the diameter of tubes. According to the results of simulation and analytical studies, the expected output can be specified logically with evaluation of operational and performance parameters. This procedure is a key step which should be considered for the optimal design of the system in different weather conditions considering energy efficiency improvements. According to the results of this research, for the simulated photovoltaic/thermal system following values shows the optimum amounts: water flow rate of 0.016 kg/s, the outer diameter of the water side pipe 1 cm and the distance between pipes in a range of 7 to 11 cm.

Comparison of Wall Thinning Analysis Results between CHECWORKS and ToSPACE

Assumptions have always been that wall thinning on the secondary side piping in nuclear power plants is mostly caused by Flow-Accelerated Corrosion (FAC). Recent studies have showed that wall thinning on the secondary side piping is caused by Liquid Droplet Impingement Erosion (LDIE), Solid Particle Erosion (SPE), cavitation, and flashing. To manage those aging mechanisms, several software such as CHECWORKS, COMSY, and BRT-CICERO have been used in nuclear power plants. Korean nuclear power plants have been using the CHECWORKS program since 1996 to date. However, many site engineers have experienced a lot of inconveniences and problems in using the CHECWORKS program. In order to work through the inconveniences and to remedy problems, KEPCO-E&C has developed a “3D-based pipe wall thinning management program (ToSPACE)” based on the experience of over 30 years in relation to the pipe wall thinning management. This study compares the results of FAC and LDIE analysis using both the CHECWORKS and ToSPACE programs with respect to validation of the wall thinning analysis results.

Alternatives of different refinement and transmission system applications in refining and reusing of wastewater at Namık Kemal University

In order to achieve sustainable goals, the detection and application of methods, which could reduce or bar waste of water, wastewater and waste electricity, are very important in establishing techniques and systems which could be used to combine social and economic aims with ecological needs. The wastewater of university is a kind of domestic wastewater, and at least 60% of the total wastewater usage consists of grey water, and this water will be reused.Domestic wastewater will primarily be collected in 2 different systems. These could be two side by side piping systems, as well as a different system to be obtained by passing a smaller diameter pipe through the same pipe. As material in this system; Waste water storage tank, discontinuous suction and force pump, A different suction pipe for negative purposes and all kinds of materials, All the equipment of the existing wastewater treatment plant will be used. The more the demands and standards of environment rise, the more necessary it has become to figure out and apply effectively different and innovative solutions. Particularly, it is really important for the countries or cities whose foundation of facilities or running those facilities cost a lot to be able to reuse wastewater. For example, the need for water increased by 45% in Istanbul (Turkey) and increased by 20 % in Sydney (Australia) and 14, 8 % in Monterrey (Mexico) in the last ten years.(2008, OECD research). It is seen that, in the countries where tourism has developed, the usage of electricity overnight is between 3-6 kWh per bed and water 600-1300 liters per bed. Ultra refining, combined purification and transmission technology (membrane, UV, transmission by vacuumetc.) which have been reconstructed and used after the 1990s, have been researched with in the scope of the present study. Reactivating the existing water purification system at Namik Kemal University central campus, which is convenient for daily usage in the summer months, and ultra refining method spurified from bacteria and utility of the systems that are determined to use in the transfer of wastewater, have been presented comparatively in the present research.

Improving Safety and Economic Feasibility of NPP by Management of Secondary Side Piping Life

Flow accelerated corrosion (FAC), which caused major accidents at Sarri-2 NPP and Mihama-3 NPP, is the main ageing mechanism of NPP secondary side piping. FAC determines the service life of piping made of carbon steel. Wear prediction using computer codes is considered a tool for life management. The paper presents analysis of computer codes of the USA, Germany and Russia and considers the advantages of computer codes for life management and repair planning. Some problems that arise from using computer codes for analyzing the results of ultrasonic thickness gauging are indicated. The paper provides the algorithm for piping life management at Japanese NPPs and proposes the ways of improving piping life management algorithm, which makes it possible to proceed to the implementation of piping repair concept according to their condition.

Impedance-matching acoustic bend composed of perforated plates and side pipes

In this article, we propose a design for an impedance-matching acoustic bend. The bending structure is composed of sub-wavelength unit cells containing perforated plates and side pipes that allow the mass density and the bulk modulus of each unit cell to be tuned simultaneously. The refractive index and the impedance of the acoustic bend can therefore be modulated simultaneously to guarantee both the bending effect and high acoustic transmission. The results of simulation of the sound pressure field distribution show that the bending effect of the proposed impedance-matching acoustic bend is very good. Transmission spectra are calculated for both the impedance-matching acoustic bend and an acoustic bend composed of the perforated plates alone for comparison. The results indicate that the impedance-matching acoustic bend successfully improves the impedance ratio while also obviously increasing the transmission.

Development of a LDIE Prediction Theory in the Condition of Magnetite Formation on Secondary Side Piping in Nuclear Power Plants

It has been thought that wall thinning on the secondary side piping in nu-clear power plants is mostly caused by Flow-Accelerated Corrosion (FAC). Recently, it has been seen that wall thinning on the secondary side piping carrying two-phase flow is caused by not only FAC but also Liquid Droplet Impingement Erosion (LDIE). Moreover, it turns out that LDIE in nuclear power plants does not result from a single degradation mechanism but also from the simultaneous happenings of LDIE and FAC. This paper presents a comparison of the mass loss rate of the tested materials between carbon steel (A106 B) and low alloy steel (A335 P22) resulting from degradation effect. An experimental facility was set up to develop a prediction model for clarifying multiple degradation mechanisms that occur together. The experimental facility allows examining liquid droplet impingement erosion in the same conditions as the secondary side piping in nuclear power plants by generating the magnetite on the surface of the test materials. The magnetite is formed by controlling the water chemistry and the temperature of fluid inside the facility. In the initial stage of the experiments, the mass loss rate of A106 B was greater than that of A335 P22. However, after a certain period of time, the mass loss rate of A335 P22 became greater than that of A106 B. It is presumed that the results are caused by the different yield strengths of the test materials and the different degrees of buffer action of the magnetite deposited on their surfaces. The layer of magnetite on the surface of A106 is thicker than that of A335 P22, due to the different amount of chrome content. In nuclear power plants, carbon steel piping having experienced wall thinning degradation is generally replaced with low-alloy steel piping. However, the materials of pipes carrying two-phase flow should be selected considering their susceptibility to LDIE.

배관감육 관리를 위한 고정식 및 탈착식 보온재 설치 경제성 분석

To perform ultrasonic testing (UT) thickness measurement of the secondary side piping installed in nuclear power plants, the insulation for preventing heat loss should be removed. The type of insulation can be divided into fixed and removable insulation. Fixed and removable insulation have their own strengths and weaknesses. Removable insulation has been installed in the components susceptible to wall thinning caused by FAC and erosion from Shin-Kori unit 1, which commenced its commercial operation in 2011. In this paper, the number of repeated inspections of components and the number of replacements of fixed insulation were estimated and a more economical way was identified based on the manufacturing and installation costs for fixed and removable insulation.

Zak phases and band properties in acoustic metamaterials with negative modulus or negative density

Zak phases in two types of acoustic metamaterials with negative density or negative modulus are studied. Different from phononic crystals based on Bragg scattering, extraordinary performance in acoustic metamaterials originates from local resonance. We find that the Zak phases in metamaterials are determined by the resonances of scatterers, side pipes, or membranes. Additionally, it is observed that the topological transition points, symmetrical properties of edge states, input impedances, and reflection phases in forbidden bands are all related to the resonances of the scatterers, and the relationship can be used to create surface states at the interface of two types of acoustic metamaterials.

Computer Analysis of Durability and Leakproofness of Multilateral Junction of Wells

The paper considers method of computer simulation of well multilateral junctions corresponding to TAML Level-4. The base stages of algorithm of stress-strain condition calculation of cased main and side pipes are described. Durability of junction depending on internal pressure is established in a kind of functional dependences. The influence of side pipe thickness and whipstock angle on junction deformation is researched.

Simultaneous realization of negative group velocity, fast and slow acoustic waves in a metamaterial

An acoustic metamaterial is designed based on a simple and compact structure of one string of side pipes arranged along a waveguide, in which diverse group velocities are achieved. Owing to Fabry-Perot resonance of the side pipes, a negative phase time is achieved, and thus, acoustic waves transmitting with negative group velocities are produced near the resonant frequency. In addition, both fast and slow acoustic waves are also observed in the vicinity of the resonance frequency. The extraordinary group velocities can be explained based on spectral rephasing induced by anomalous dispersion on the analogy of Lorentz dispersion in electromagnetic waves.