Bypass Pipe Research Articles

Tracking control of dynamic ammonia coverage ratio references based on DC-SMC under a novel SCR-DeNOX structure

In response to the growing challenges of nitrogen oxides (NOX) emission control, NH3-based selective catalytic reduction (SCR) technology has been widely adopted to reduce NOX emission from marine diesel engine exhaust. In this study, the SCR mechanism model is based on a refined eight-state model. A novel structure of SCR-DeNOX system is established, which incorporates a by-pass valve and pipe. Unlike existing parallel and series SCR-DeNOX platforms, the novel structure shows a certain advantage in reducing NH3 and maintains a relatively high NOX conversion efficiency. Adaptive sliding mode observers (ASMO) are designed to generate dynamic ammonia coverage ratio references, replacing traditional fixed references. In addition, they also address the variations in the SCR-DeNOX model. The sliding mode control (SMC) is used to track the ammonia coverage ratio reference in upper cell by controlling ammonia injection. The decoupling with SMC (DC-SMC) is proposed to track the ammonia coverage ratio reference in the lower cell by controlling split ratio. The simulation results show the system with DC-SMC shows a 15.46% improvement in NOX conversion efficiency compared to that with SMC. Additionally, it shows a lower NH3 cost.

Evaluating sugarcane bagasse fly ash as a sustainable cement replacement for enhanced performance

This study evaluated the potential of sugarcane bagasse fly ash, collected from boiler exhaust stacks via a bypass pipe, as a renewable supplementary cementitious material. The bagasse fly ash was ground into three different particle sizes (D50 of 10, 20, and 30 μm) and characterized in terms of morphology, porosity, specific surface area, and pozzolanic activity. The influence of the ashes on paste hydration was investigated using isothermal calorimetry. Mortars were then tested with 20% cement replacement by fly ash, analyzing packing density, compressive strength evolution, and durability against sulfuric acid. Results indicated the suitability of the fly ash as a supplementary cementitious material, with low contamination and greater pozzolanic activity at smaller particle sizes. This enhanced initial hydration and long-term strength, with finer ashes showing superior mechanical properties when compared to the reference mortar (an 8% increase). Mortars with fly ash exhibited higher packing density and reduced mass loss under sulfuric acid attack, but increased water absorption and capillarity, alongside decreased compressive strength compared to the reference. Briefly, the findings highlighted that the potential of bagasse fly ash as a promising low cost and eco-beneficial material for sustainable construction practices.

Pump-stopping-induced hydraulic oscillations in long-distance district heating system: Modelling and a comprehensive analysis of critical factors

To achieve low-carbon goals, long-distance district heating (LDH) systems are widely applied, which utilize the waste heats from renewable energy power plants and waste incineration plants. The hydraulic oscillations induced by pump-stopping in LDH systems may give rise to critical incidents, such as pipeline ruptures and heating disruptions. The systematic analysis of hydraulic oscillations induced by pump-stopping and the subsequent revelation of critical factors that mitigate their intensity are fundamental prerequisites for ensuring the safety and reliability of LDH system. In this paper, firstly, a pump-stopping hydraulic transient model of the LDH system is established based on the distributed parameter method. Then, combining the method of characteristics (MOC) and the Newton iteration method, the numerical solution scheme for this model is proposed. Finally, taking a 20 km LDH system as an example, the characteristics of hydraulic oscillations induced by pump-stopping is analyzed, and the key factors influencing the intensity of these hydraulic oscillations are investigated. In addition, the differences between hydraulic oscillations induced by pump-stopping and those induced by sudden faults on pipelines are also analyzed. The results indicate that an optimal pump inertia moment value and a properly sized bypass pipe at the pump significantly mitigate hydraulic oscillations, while the influence of constant pressure at the heat source inlet on hydraulic oscillations can be negligible. Our study has important reference value for improving the safe and reliable operation of LDH systems.

EPANET INP Code for Incomplete Mixing Model in Cross Junctions for Water Distribution Networks

EPANET can be used to simulate quality on water distribution networks. The EPANET model considers that the mixing on cross junctions of pipes is complete, including the cases of two contiguous inlets and two contiguous outlets. The output concentration of this model is the same value on the two outlets. This research proposes a code to generate an INP file for EPANET but with an incomplete mixing scenario in the crossings. The cross junctions are identified, and their hydraulic and concentration conditions are analyzed for each quality time step. Bypass pipes are included in the model to remove concentrations generated by the complete mixing model, preserve continuity in water quality and ensure the correct allocation of concentration. The concentration at the outlets is obtained by a system of polynomial equations representing the incomplete mixing model as a function of the hydraulic and concentration at the junction inlets. The outlets’ concentrations are incorporated by setpoint boosters. Validations are described to demonstrate the achievement of the new code. An average relative concentration difference of up to 14% is obtained in networks with different scenarios for the two mixing models.

Investigation and assessment of the optimum conditions of solar heat source hybrid desiccant cooling system under different modes

In this study, the hybrid desiccant cooling system (HDCS) with solar heat source is experimentally studied, and various alternative methods are suggested for the problem of the cooling system which is of concern due to the characteristics of solar power, empirical experiments and the applicability of solar heat sources to HDCS. The results of empirical experiment are analyzed through daily data, while cooling temperature is set to Tset = 22 °C (setting temperature) under the conditions of TOA = 32 °C (outdoor air temperature), RHOA = 45 % (outdoor air relative humidity), Tst = 70–80 °C (storage top temperature), Treg = 70 °C (regeneration temperature), dehumidification = 4.5 g/kg, COPelec = 4.8, and COPth = 2–4. When Tst is higher than 85 °C, it may damage the system due to material characteristics of desiccant rotor. Therefore, flow rate of the load-side pipe is lowered by adding a bypass pipe to load-side pipe, and OA (outdoor air) of 60–70 °C suitable for regeneration of the desiccant rotor can be supplied. When the Tst is low, the Tst is increased by lowering the Treg and rather absorbing the heat of the condenser and radiating the heat in the heat storage tank. If the Tst is higher than 85 °C but no separate action can be taken on the load side, a radiator can be installed at the solar system to control the temperature of storage tank. If hot water supply is controlled according to the temperature of storage tank, the solar heat source can be stably applied to the HDCS.

Thermal analysis and optimization of the heat exchange system in the test loop for the fuel assembly steady-state irradiation based on a re-evaluation method

In order to verify the rationality of the design and reliability of the manufacturing process and provide a basis for the final design of the fuel assembly, it is necessary to carry out a steady-state irradiation test for the new fuel assembly in the pressurized water test loop with high temperature. Based on the historical experimental data feedback, a re-evaluation method for acquiring heat transfer performance of the regenerative heat exchanger was established for the fuel assembly steady-state irradiation in the pressurized water test loop with high temperature to accurately predict the ability of the test loop under different irradiation test parameters. It is shown that the heat exchange power prediction of the heat exchanger is accurate and effective by correcting the heat transfer coefficient of the regeneration section and the cooling section of the regenerative heat exchanger at the same time coupled with carrying out the re-evaluation of the heat exchange capacity. The traditional calculation power is generally higher than the re-evaluation power, and the magnitude of the increase is closely related to the primary water flow, but is weakly affected by the primary water inlet temperature. Meanwhile, it has an obvious effect on increasing the heat exchange power of the heat exchanger at low parameters that short-circuited water bypass pipes in the regeneration section are set. Furthermore, the heat exchange system in the steady-state test loop should be designed as a series–parallel switchable scheme to satisfy the wide range of power requirements.

Topology optimization of thermally activated building system in high-rise building

The building sector accounts for nearly 1/3 of global energy end-use and associated carbon emissions. Fulfilling buildings' thermal demand in an efficient way is critical for decarbonizing the building sector. Therefore, this paper introduces the thermally activated building system (TABS) as an energy retrofit solution. A TABS floor-by-floor return water temperature control approach is proposed to reduce buildings' energy use and carbon emissions. The approach includes the topology optimization of TABS and flow control. The bypass pipe connections of the TABS to each floor, namely, the floor-by-floor pipe network topology, have been optimized by using genetic algorithms to achieve the lowest total cost. A case study of a high-rise building located in Beijing demonstrates that the proposed approach can improve the system's energy efficiency compared to the conventional TABS without optimization. The reduction of energy cost can be up to 11.21% with a 13.53% annual emission reduction. In general, the proposed TABS floor-by-floor return water temperature control approach can significantly improve the building efficiency comprehensively, therefore can be considered as a promising energy retrofit solution for the decarbonization of high-rise buildings.

Development of integrated semi-active adaptive vibration control system for bridges subjected to traffic loads

Nowadays, the fluid viscous damper is the most conventional energy dissipation system implemented in bridge structures to control the vibrations due to traffic loads. However, to effectively protect the bridge against frequent and severer vibrations, it is required to adapt the function of the damper according to the variable traffic loads. In this research, an Integrated Semi-Active Adaptive Vibration Control System is developed for the bridge structures. This control system consists of a Semi-Active Bypass Fluid Damper (SABFD), a programmable logic controller (PLC), pressure transducers, and displacement sensors. Semi-Active Bypass Fluid Damper is a hydraulic cylinder with a pair of external bypass pipes with motorized electric flow control valves which are installed in the middle of pipes to control the flow rate of the fluid. A programmable logic controller (PLC) is implemented to manage the operation of motorized valves according to the movement of the bridge.Therefore, the integrated control system is able to function as a real-time controller during its operation. To develop the control system, the performance of the SABFD device has been assessed through analytical model of the various control valve positions. Then, according to the structure response, a fuzzy control algorithm has been adapted in the PLC controller.Afterward, the prototypes of the SABFD and the PLC controller have been fabricated and a series of cyclic load tests have been conducted by using a dynamic actuator. The outcomes of the numerical analysis and results of the experimental tests revealed that the developed device is capable of generating a wide range of forces during device operation. The developed fuzzy control algorithm is then implemented to the finite element model of the bridge equipped with SABFD, and the results proved that the real-time control system effectively limits the bridge displacements according to the pre-defined fuzzy control rules.

Development of adjustable fluid damper device for the bridges subjected to traffic loads

In this research, an Adjustable Bypass Fluid Damper (ABFD) is developed by utilizing a pair of external fluid flow pipes and flow control valves. The flow control valves control the flow pressure of the fluid passing through bypass pipes and adjusted the function of the fluid damper to limit the displacement of the structure within the allowable range. Therefore, the function of the fluid damper device is adjustable according to the displacement of the structure.The ABFD device is developed through implementing an adjustable valve in bypass pipes that able to change and adjust the flow and pressure of the oil inside the viscous damper during movement of piston under applied vibrations and control the resultant damping and resistance force of the damper device. Therefore, through the new proposed design, the action of viscous damper has been changed from passive control device to an adjustable system which is capable to function as an device with different capacities and also able to change the response from a damping device to a restrainer system. The analytical model of the proposed ABFD device is developed and the performance of the device has been formulated according to the control valve position. Then the finite volume model of the moving fluid inside the device has been developed and the function of the device was evaluated through Computational Fluid Dynamics analysis.In the next step, the prototype of ABFD has been fabricated and experimental tests have been conducted using a dynamic actuator to evaluate the performance of the device in various control valve conditions.The numerical analysis and experimental test results for the ABFD prototype revealed that the developed device is capable of developing a wide range of damping levels and there is a desirable agreement between numerical predictions and experimental results.Thereafter, to examine the effect of the application of the ABFD device in the bridge structures, the proposed ABFD device was implemented in the 19/5 California overcrossing bridge. The considered bridge equipped with an ABFD device is modeled using the finite element method and it’s subjected to the passing vehicle loadings. The results showed that the bridge's response is dramatically improved with the implementation of the six ABFD dampers and the peak displacement of the structure reduces by 35 percent while the control valves are half-open.

Изменение конструкции малого опытового бассейна для комплексных испытаний подвесных лодочных моторов

When studying the characteristics of the outboard motors with capacity of more than 10 kW weighing over 100 kg at full equipment, the Department of Water Transport Operation of Astrakhan State Technical University needed to change the design of a small experimental tank. Previously, the small experimental tank was adapted for testing outboard motors with capacity not exceeding 8 l/s - 6 kW and weight up to 25 kg having such technical indicators as the screw stop, the developed power of the outboard motor, tank water temperature, exhaust gas temperature, fuel consumption, rate of heating the aquatic environment during the engine operation, the number of revolutions 
 of the engine crankshaft, the number of revolutions of the screw, with possibility of environmental studies of noise levels, vibration levels, as well as harmful discharges and exhaust emissions of outboard motors by sampling water and gases. In addition to sensors and devices designed to measure technical and environmental indicators, the small experimental tank was previously equipped with an auxiliary equipment: supply and exhaust ventilation, a water level gauge in a basin tank, a steam compressor refrigeration unit, a water supply and drainage system with sampling fittings, a gas sampling probe, a rotary rod for installing a noise meter, a platform with steps, general and local lighting fixtures. There has been illustrated a layout of an experimental tank covered with heat-insulating paint from the outside. In the course of changing the structure there was installed a lifting boom and an external transom. The tank bowl was upgraded by installing a bypass pipe. The described technical solutions have expanded the possibilities of the small experimental tank in conducting the research on outboard motors.

Improving Effectiveness of Flow Measurement by Bypass Method: A Technique Applied to Thermal Mass Flowmeter

Abstract Fluid velocity or flow rate measurement, by flow sampling or bypassing flow from main pipelines, offers several advantages, like reducing the footprint of the flowmeter and avoiding the stoppage of a process during flowmeter repair or replacement. The flow measurement technique could be thermal mass flowmetry, a popular flow measurement method. A major limitation in the bypassing technique is the low flow rate through the bypass pipe resulting in a weak flowmeter thermal signal or reduced sensitivity to flow. This paper describes the usage of a validated computational fluid dynamics (CFD) model to investigate several bypass pipe designs to maximize fluid flow rate through the bypass pipes installed on the main pipeline and consequently maximize the thermal signal generated by an elementary thermal mass flowmeter installed on the bypass pipe. Investigations reveal that bypass design modification can improve thermal signal strength by as much as 38% with respect to that obtained in the baseline bypass design.

Development of Highly Efficient Radiation-Convective Recuperator for Furnace of Secondary Aluminum Melting

The high efficient design of the radiation-convective recuperator with secondary emitters have been proposed, in which due to the rational arrangement of heating surfaces, as well as due to the installation of secondary emitters in flues, an increase in heat perception is transmitted to the secondary heat carrier – preheating air. High efficiency of air preheating is provided by two-stage heating: 1st stage of heating – the internal air ring channel with bilateral heating which is washed by combustion products from the parties of the central cylindrical and peripheral ring channels of combustion products; 2nd stage of heating – the external air ring channel in which unilateral heating by products of combustion from the peripheral ring channel of products of combustion is organized. Inner and outer annular air ducts (tanks), interconnected by bypass pipes. To increase the efficiency of heat transfer in the considered recuperator in the central channel of combustion products is placed emitter, which consisting of intersecting radial plates, and in the annular channel of combustion products are placed auxiliary emitters, which made in the form of flat radial edges. These emitters provide an increasing in total heat flux to the walls of the channels of the recuperator. On the basis of the conducted theoretical researches, engineering calculations and CFD – modelling the characteristics of operation of the recuperator for its installation on the furnace of secondary smelting of aluminium are defined. The main advantages of the new design of recuperator are high thermo-hydraulic efficiency, compactness and low metal consumption, ease of installation on the furnace and no need for placement in separate chimneys. It is established that the recuperator provides air heating ta,ex ~ 400 °C at an acceptable aerodynamic drag (pressure drop) on the air track (∆pa ~ 1000 Pa). Appropriate design documentation has been developed for the manufacture of the recuperator, which is installed on a pilot furnace of secondary aluminium smelting by California Die Casting (USA).

WITHDRAWN: Viscoelastic loop strategy for water hammer control in a pressurized steel pipeline

Abstract The challenges of water hammer phenomenon impose many technical and economic barriers to the design and operation of the pressurized hydraulic systems. So the objective of most literature in this field was finding an applicable strategy that was capable to suppress the threatening of hydraulic transient and fulfill the required technical and economic limits of the project. In this paper, an experimental investigation is presented to verify the effectiveness of the viscoelastic loop strategy to control and damp the water hammer triggered in the pressurized pipeline due to pump’s trip or downstream valve closure. This strategy comprises two viscoelastic bypass pipes are configured to form a counter clockwise loop that allow to the flow in certain direction and restrain its opposite one. On the other hand, the performance of viscoelastic loop strategy is compared to the classical air vessel device to control the induced hydraulic transients. Further, the experimental results revealed the viscoelastic loop strategy is very effective to control the water hammer with overall maximum pressure damping efficiency reaches to (69.5%). Furthermore, the viscoelastic loop strategy is superior to the classical air vessel device for different transients trigger conditions in the most cases of the experiments.

Performance Evaluation of Penstock By-Pass System Modification on HEPP (Hydro Electric Power Plant) with CFD Analysis to Optimize Power Consumption

This paper proposes a feasibility test for the performance modification of the penstock by-pass system using CFD (Computational-Fluid-Dynamic) simulations to optimize the energy use of the water-cooling system. The main advantage of this modification is the power savings of 45%-50%. This modification of the by-pass system is carried out with the aim that the final flowrate and pressure of modification can replace the Main-Water-Supply-Pump (MWSP) operation function in the unit’s main cooling system. CFD simulation is carried out on the impact of a pressure drop of 40-4 bar with a flow of 0.3 m3/s on the by-pass pipe flow of the existing penstock system and the condition of the pipe modification to be carried out. The numerical simulation results show that the MWSP network structure can accept load flow pressures varying 40-4 bar. This simulation refers to the conditions in HEPP Saguling Indonesia and can be applied to others.

Evaluation of the trailbuilder hydraulic drive thermal preparation

One of the main problems in operation of road-building machines in conditions of low negative ambient temperatures is the hydraulic drive thermal preparation. The hydraulic equipment is located throughout the machine and need a local thermal warming otherwise its cold start results in its intense wear. We propose the warming method that comprises circulation of a prewarmed hydraulic fluid from the hydraulic tank through the piston and rod chambers of hydraulic cylinder without rod motion. This is ensured by installation of a bypass pipe and a valve connecting the hydraulic cylinder piston and rod chambers. To evaluate operability of the hydraulic cylinder warming system we determined the fluid circulation conditions depending on the fluid flow rate and its temperature. To check these conditions, we made calculations for a trailbuilder hydraulic drive with a ripper.

Empirical data-driven multi-layer perceptron and radial basis function techniques in predicting the performance of nanofluid-based modified tubular solar collectors

In the present study, the modified evacuated tube solar collector (METSC) with a bypass pipe utilizing copper oxide/distilled water (Cu2O/DW) nanofluid is experimented. Then, the performance of METSC was predicted through Artificial Neural Networks (ANNs) techniques. The input variables were different volumes of the storage tank from 5 to 8 l, various diameters of the bypass pipe from 6 to 10 mm, and various volumetric concentration of the nanofluid from 0 to 0.04. Also, the output variables were the temperature difference of fluid in 1-h period and the energetic efficiency of METSC. The results demonstrated that the METSC performance was mostly impacted by the tank volume alteration. Moreover, the optimum bypass tube diameter value was obtained, and it was denoted that using the Cu2O/DW nanofluid enhances the daily energy efficiency of METSC up to 4%. Furthermore, it was shown that both MLP and RBF techniques are two reliable algorithms to predict the thermal characteristics of an METSC. The maximum amounts of mean relative percentage error for MLP and RBF algorithms were reported as 0.576 and 0.907, respectively. Hence, two mathematical models were reported for formulating the output variables in terms of the input variables using the MLP technique.

Modeling and Simulation of Pigging for a Gas Pipeline Using a Bypass Pig

The pipeline inspection gauge (PIG, lowercase pig is commonly used) with a bypass valve is widely used in pipeline inspection because it operates at a low speed without reducing the flow rate. Understanding the dynamics of a bypass pig in a gas pipeline would contribute to the design of the pig and the control of pig speed. This paper deals with the dynamic model for the process of a bypass pig travelling through a hilly gas pipeline. The method of characteristics (MOC) is used to solve the equations of unsteady gas flow. The backward flow of the gas in the bypass valve and pipe is shown by a simulation of pigging for a hilly gas pipeline. Parametric sensitivity analysis of pigging in the horizontal gas pipe using a bypass pig is then carried out. The results indicate that the speed of a bypass pig is most sensitive to the gas speed in the pipe followed by the bypass area and the friction of the pig. A formula, obtained from the results of the simulations using response surface methodology (RSM), is presented to predict the steady speed of a bypass pig in the horizontal gas pipeline.

Increasing the energy flexibility of existing district heating networks through flow rate variations

The possibility of recovering waste and renewable heat in urban areas has made district heating networks one of the key infrastructures for decarbonising the heating sector in Europe. The ability to shift the heat production over time is an important asset to improve the competitiveness of both new and existing networks. To this purpose, the present study evaluates the flexibility potential provided by the water volume enclosed in the network pipelines using the district heating network of Verona (Italy) as a case study.Given the users heat demand in two representative weeks, computer simulations were carried out to calculate the network's thermal response to circulating flow rate variations. The latter were designed to cause an early or late shift in the daily peak thermal load. The local temperature drop at the users substations compared to the current situation was used as a relative discomfort indicator. The simulations were carried out using the model NeMo, which has been attached as supplementary material to this publication. The simulation results show that the network pre-charge strategy achieves significant benefits in terms of both peak shaving and load shifting with a limited impact on discomfort for the users. Furthermore, the paper shows that the available storage capacity of the network is significantly influenced by the duration of the flow adjustment, by the average velocity of the heat carrier fluid and by the daily heat demand pattern. Finally, it is shown that the energy flexibility of the network also depends on its topology. In this regard, the article provides preliminary indications on the number and position of the bypass pipes needed to implement the proposed flow rate variations.In conclusion, the article shows that the thermal inertia of the heat carrier fluid is an interesting source of flexibility for existing networks, and the results highlight its potential and limitations.

Experimental and numerical investigations on the thermal performance of a modified evacuated tube solar collector: Effect of the bypass tube

Many factors impact the thermal efficiency of the evacuated tube solar collectors (ETSCs) and numerous studies have been carried out to increase the efficiency of ETSCs. In this study, the stagnant region at the bottom of the evacuated tube has been removed using a bypass tube to connect the storage tank to the bottom of the modified evacuated tube. The thermal performance of a modified evacuated tube solar collector (METSC) has been investigated experimentally and numerically. The thermal characteristics of the METSC were compared to those of a commercial sample under equal environmental conditions. Furthermore, the impact of the diameter of the bypass pipe on the velocity profile, and temperature distribution of the fluid inside the modified collector has been investigated numerically to achieve the optimum diameter. The results demonstrate that this structure modification improves the collector performance due to removing the stagnant region at the bottom of the evacuated tube and the storage tank. This modification made the temperature distribution inside the pipe and tank more uniform, and increased the efficiency up to 11%. Moreover, useful gain of the solar collector in the modified model was 25% more than that of the typical model over a one-hour period. In addition, for the same duration, the average temperature of water inside the tank enhanced by 1.5 °C in the METSC in comparison to the typical model under equal environmental conditions.

Development of Divergent Fluid Wall Damper for Steel-Framed Structures Subjected to Dynamic Load

ABSTRACT This article presents the development of new adjustable and adaptive designs of divergent fluid wall dampers (DFWDs) that can diminish the effect of earthquakes on framed structures. The concept and mechanism of DFWDs is based on the bypass system, which is made by controlling the fluid flow inside the wall damper container using bypass pipes and by controlling the fluid pressure through a double-acting valve. The prototype of the DFWD device is fabricated based on a developed design, and the performance of the DFWD installed in steel frames is evaluated through experimental tests. For this purpose, three steel frames with the same geometric specifications are casted and tested in equal conditions, which include bare frame (BF), braced frame (BrF), and frame equipped with DFWD. All specimens are subjected to dynamic cyclic load and the response of the DFWD is evaluated when the valves are 100% open, 50% open, and 100% closed in comparison with the BF and BrF system to assess the performance of the DFWD in various conditions. The results indicate that the frame furnished with the DFWD in all conditions of fully open, half-open, and fully closed valves were able to absorb and dissipate more force than the BF by almost 28%, 53%, and 73%, respectively.