Manifold Design Research Articles

Thermal-hydraulic performance of convective boiling jet array impingement

Jet impingement boiling is investigated with regard to heat transfer and pressure drop performance using a novel laser sintered 3D printed jet impingement manifold design. Water was the working fluid at atmospheric pressure with inlet subcooling of 7oC. The convective boiling performance of the impinging jet system was investigated for a flat copper target surface for 2700≤Re≤5400. The results indicate that the heat transfer performance of the impinging jet is independent of Reynolds number for fully developed boiling. Also, the investigation of nozzle to plate spacing shows that low spacing delays the onset of nucleate boiling causing a superheat overshoot that is not observed with larger gaps. However, no sensitivity to the gap spacing was measured once boiling was fully developed. The assessment of the pressure drop performance showed that the design effectively transfers heat with low pumping power requirements. In particular, owing to the insensitivity of the heat transfer to flow rate during fully developed boiling, the coefficient of performance of jet impingement boiling in the fully developed boiling regime deteriorates with increased flow rate due to the increase in pumping power flux.

Integral Sliding Manifold Design for Linear Systems With Additive Unmatched Disturbances

This note offers an integral sliding manifold design method for linear systems that minimizes the impact of unmatched constant external disturbances. System sensitivity upon an unmatched disturbance vector is assessed by the steady-state dependent criterion function. The derived procedure easily finds a unique integral sliding manifold that minimizes a quadratic optimization criterion. Applicability of this method in case of slowly-varying disturbances is supported by determining disturbance frequency limit that guarantees satisfactory performance. The proposed approach has been demonstrated on a numerical example and verified by simulations.

Optimization of manifold design for 1 kW-class flat-tubular solid oxide fuel cell stack operating on reformed natural gas

Abstract This study focuses on optimizing the manifold design for a 1 kW-class flat-tubular solid oxide fuel cell stack by performing extensive three-dimensional numerical simulations on numerous manifold designs. The stack flow uniformity and the standard flow deviation indexes are implemented to characterize the flow distributions in the stack and among the channels of FT-SOFC's, respectively. The results of the CFD calculations demonstrate that the remodeled manifold without diffuser inlets and 6 mm diffuser front is the best among investigated designs with uniformity index of 0.996 and maximum standard flow deviation of 0.423%. To understand the effect of manifold design on the performance of stack, both generic and developed manifold designs are investigated by applying electrochemical and internal reforming reactions modeling. The simulation results of the stack with generic manifold are validated using experimental data and then validated models are adopted to simulate the stack with the developed manifold design. The results reveal that the stack with developed manifold design achieves more uniform distribution of species, temperature, and current density with comparatively lower system pressure drop. In addition, the results also showed ∼8% increase in the maximum output power due to the implementation of uniform fuel velocity distributions in the cells.

CFD Analysis and Design of Detailed Target Configurations for an Accelerator-Driven Subcritical System

High-fidelity analysis has been utilized in the design of beam target options for an accelerator-driven subcritical system. Designs featuring stacks of plates with square cross section have been investigated for both tungsten and uranium target materials. The presented work includes the first thermal-hydraulic simulations of the full, detailed target geometry. The innovative target cooling manifold design features many regions with complex flow features, including 90° bends and merging jets, which necessitate three-dimensional fluid simulations. These were performed using the commercial computational fluid dynamics code STAR-CCM+. Conjugate heat transfer was modeled between the plates, cladding, manifold structure, and fluid. Steady-state simulations were performed but lacked good residual convergence. Unsteady simulations were then performed, which converged well and demonstrated that flow instability existed in the lower portion of the manifold. It was established that the flow instability had little effect on the peak plate temperatures, which were well below the melting point. The estimated plate surface temperatures and target region pressure were shown to provide sufficient margin to subcooled boiling for standard operating conditions. This demonstrated the safety of both potential target configurations during normal operation.

Air recovery assessment on high-pressure pneumatic systems

A computational simulation and experimental work of the fluid flow through the pneumatic circuit used in a stretch blow moulding machine is presented in this paper. The computer code is built around a zero-dimensional thermodynamic model for the air blowing and recycling containers together with a non-linear time-variant deterministic model for the pneumatic three stations single acting valve manifold, which, in turn, is linked to a quasi-one-dimensional unsteady flow model for the interconnecting pipes. The flow through the pipes accounts for viscous friction, heat transfer, cross-sectional area variation, and entropy variation. Two different solving methods are applied: the method of characteristics and the Harten-Lax-Van Leer (HLL) Riemann first-order scheme. The numerical model allows prediction of the air blowing process and, more significantly, permits determination of the recycling rate at each operating cycle. A simplified experimental set-up of the industrial process was designed, and the pressure and temperature were adequately monitored. Predictions of the blowing process for various configurations proved to be in good agreement with the measured results. In addition, a novel design of a valve manifold intended for the polyethylene terephthalate (PET) plastic bottle manufacturing industry is also presented.

Multi-objective optimization of a natural aspirated three-cylinder spark ignition engine using modified non-dominated sorting genetic algorithm and multicriteria decision making

The main purpose of this study is to find a special set of filling and emptying parameters of a three-cylinder engine, including geometrical design of intake manifold, intake and exhaust valve timing as design variables of the multi-objective optimization problem, which lead to the best values of BSFC (Brake Specific Fuel Consumption), and torque of the engine at all working speeds as four separate objective functions. The modified Non-dominated Sorting Genetic Algorithm (NSGA-II), which is an evolutionary Pareto-based method, is used as the optimization algorithm, and the technique for order of preference by similarity to ideal solution is used as a Multi-Criteria Decision Making Method to select the trade-off design based on different design strategies through the design vectors which are proposed. Group Method of Data Handling-type of Artificial Neural Networks is used to predict the relation between the design variables and the objective functions based on a 243-sized set of samples, which are chosen by Factorial method, and the corresponding engine designs are simulated using GT-SUITE as an Engine Simulation Software. The method of simulation is verified by comparison of experiment and simulation results. The verification process shows that the engine simulation code could predict the engine's performance by 4.78% error. Convergence and start point independence of the optimization algorithm (modified NSGA-II) is also investigated. The final results show remarkable improvement in BSFC and torque at 3500 RPM and mean value of BSFC at all working speeds along with a small reduction in mean value of the engine's torque at all working speeds compared to corresponding characteristics of a similar three-cylinder engine.

On switching manifold design for terminal sliding mode control

In this paper, a general design scheme is proposed for finite-time switching mode manifolds and corresponding nonsingular controllers. The reduced system is obtained from terminal sliding mode control (TSMC) and its homogeneity is investigated, which also illustrates that TSMC is finite-time control by the homogeneous theory. Based on the homogeneity analysis, a design proposal is provided for general finite-time switching manifolds and corresponding controllers, which guarantee that all states of a controlled system are finite-time convergent to the origin. In simulations, three finite-time switching manifolds are presented and the corresponding controllers are validated to perform the finite-time control for the double integral system.

Effects of flow field design on water management and reactant distribution in PEMFC: a review

The performance of a proton exchange membrane fuel cell (PEMFC) stack is affected by many factors, including the operating conditions, flow field and manifold design, and membrane performance. To achieve the desired PEMFC performance, the reactant must be uniformly distributed and effectively diffused into the catalyst layer for the electrochemical reaction. Water management and reactant distribution in fuel cells are crucial because they affect the distribution and diffusion rate of the reactant. This paper reviews the important research results reported in recent years related to the effects of water and reactant distribution on the performance and life span of PEMFC stacks.

Final design of ITER thermal shield manifold

The ITER thermal shield is actively cooled by 80K pressurized helium gas. The helium coolant flows from the cold valve box to the cooling tubes on the TS panels via manifold piping. This paper describes the final design of thermal shield manifold. Pipe design to accommodate the thermal contraction considering interface with adjacent components and detailed design of support structure are presented. R&D for the pipe branch connection is carried out to find a feasible manufacturing method. Global structural behavior and structural integrity of the manifold including pipe supports are investigated by a finite element analysis based on ASME B31.3 code. Flow analyses are performed to check the flow distribution.

Cold Flow Simulation of Helical Intake Manifold for Single Cylinder CI Engine

In 21st century primary purpose of Internal Combustion (IC) engine inventors is to accomplish dual objectives of finest performance and reduced emission. For maximizing mass of air induced into cylinder during suction stroke intake manifold design should be optimized. Present work primarily incorporates the effect of helical intake manifold on air motion and turbulence inside the cylinder at different crank angles. Three dimensional models of intake manifold and cylinder are generated in Creo Parametric 3.0 and meshed using Ansys 16.0. The flow characteristics of air inside intake manifold as well as engine cylinder are analysed in FLUENT 16.0.

Validation of a Discrete Model for Flow Distribution in Dividing-Flow Manifolds: Numerical and Experimental Studies

A novel discrete model with variable flow coefficients is developed for dividing-flow manifold design. The applicability and accuracy of the new model is also investigated, and a validation procedure is performed. Dimensionless volume flow rate distributions along a simple dividing-flow manifold are calculated with two different approaches: the discrete model and a three-dimensional CFD model are applied. In order to validate the calculated results, laboratory experiments are carried out. Results of the discrete model compare favourably with high resolution CFD results and also with experimental data, which underlines the applicability of the new loss coefficient parametrisation used in the discrete model.

Simulation on engine characteristic improvement by re-designing intake manifold

In this paper, a simulation of DI diesel engine 1 cylinder, model RV165-2 is used to investigate the effect of intake manifold design on the volumetric efficiency and characteristics by using AVL BOOST software. The proposed plans are evaluated and compared with available models. Conditions of simulation is based on the structure of engine and parameters from experimental test. The parameters of performance, combustion and emission characteristics are selected as evaluation criteria. The results of optimizing intake manifold are increasing volumetric efficiency, ability to blend the mixture of fuel and air, better combustion and increasing engine power, reducing fuel consumption and emission.

Optimization of the combustion system of a medium duty direct injection diesel engine by combining CFD modeling with experimental validation

The research in the field of internal combustion engines is currently driven by the needs of decreasing fuel consumption and CO2 emissions, while fulfilling the increasingly stringent pollutant emissions regulations. In this framework, this research work focuses on describing a methodology for optimizing the combustion system of Compression Ignition (CI) engines, by combining Computational Fluid Dynamics (CFD) modeling, and the statistical Design of Experiments (DOE) technique known as Response Surface Method (RSM). As a key aspect, in addition to the definition of the optimum set of values for the input parameters, this methodology is extremely useful to gain knowledge on the cause/effect relationships between the input and output parameters under investigation.This methodology is applied in two sequential studies to the optimization of the combustion system of a 4-cylinder 4-stroke Medium Duty Direct Injection (DI) CI engine, minimizing the fuel consumption while fulfilling the emission limits in terms of NOx and soot. The first study targeted four optimization parameters related to the engine hardware including piston bowl geometry, injector nozzle configuration and mean swirl number (MSN) induced by the intake manifold design. After the analysis of the results, the second study extended to six parameters, limiting the optimization of the engine hardware to the bowl geometry, but including the key air management and injection settings. For both studies, the simulation plans were defined following a Central Composite Design (CCD), providing 25 and 77 simulations respectively.The results confirmed the limited benefits, in terms of fuel consumption, around 2%, with constant NOx emission achieved when optimizing the engine hardware, while keeping air management and injection settings. Thus, including air management and injection settings in the optimization is mandatory to significantly decrease the fuel consumption, by around 5%, while keeping the emission limits.

Engineering design and analysis of Indian LLCB TBM set

India is developing Lead Lithium cooled Ceramic Breeder (LLCB) Test Blanket Module (TBM) for testing in ITER for the validation of fusion blanket design tools, tritium breeding performance and high grade heat extraction capability relevant to Indian DEMO. LLCB TBM is designed to withstand various ITER loads and its combinations, like thermal, mechanical including the high pressure coolant loads, electromagnetic loads during plasma disruption and seismic loading conditions. LLCB TBM system is designed in compliance with ITER Safety requirements and guidelines. A few challenging part in the design includes the design of helium cooled First Wall (FW) and back plates, the attachment system between TBM and the shield block to withstand loads for all the ITER operational modes, routing of high temperature process pipes between TBM and the shield block, interfaces between process pipes and the connecting flange, design of manifolds of different process fluids etc. Analysis has been performed on the LLCB TBM set using a Finite Element code, ANSYS. Relevant codes and standards, namely the French code RCC-MR, has been followed for the design analysis. The details of the analysis and further plans and proposals for improvement in design will be discussed in this paper.

A manifold design problem for a plate-fin microdevice to maximize the flow uniformity of system

An optimum design problem to determine the optimum shapes for three-dimensional manifolds of plate-fin microdevice for the best system uniformity of flow ratios is examined in this study. The Levenberg–Marquardt Method (LMM) and a general purpose commercial code CFD-ACE+ are utilized to minimize both the system non-uniformity and manifold areas of the microdevice. Two third-order-polynomial functions are used to simulate the boundary shapes for inlet and outlet manifolds, and four different optimization design problems are examined to demonstrate the validity of the present study. The results obtained from the LMM are justified based on numerical experiments, and when applying two third-order-polynomial functions to construct the shapes of manifolds, the designed plate-fin microdevice always has better system uniformity than the design with linear lines in constructing the shapes of manifolds since a 12.08% improvement for the system non-uniformity in the present design, Type OPT4, can be achieved when comparing with the previous optimal design, Type B-O609.

Mechanistic Three-Dimensional Analytical Solutions for a Direct Liquid Fuel Cell Stack

Abstract An optimal or near to optimal design and operation of a direct liquid fuel cell (DLFC) stack requires an understanding of the relevant physical phenomena across length scales in the stack. In particular, perturbations between cells can arise due to external manifold design as well as variations in material and design parameters between cells. In this work, we seek to derive closed-form analytical expressions that capture the global stack performance, as well as individual cell behavior such as cell potential, current density, and methanol distribution. This approach allows for the simulation of large stacks with near to negligible computational overhead. Finally, the solutions are demonstrated for a stack subjected to perturbations in the anode inlet velocity of each cell.

Design and analysis of inlet manifold of a four stroke petrol engine by increasing tumble flow rate and reducing air pollution using aerofoil plate

This Research targets the moment of tumble and swirl function of air flow in cylinder. It is explained by introducing aerodynamically efficient aerofoil plate in the path of inlet stream of air with fuel mixture. In normal level, Engine have cylinder and inlet manifold geometry that lead to tumble motion and better mixture of air and fuel. The motion of tumble is entirely different than traditional method. The new level research carries the manifold with 8mm and 10mm aerofoil plate for the amalgamation of fuel and air. By the low level speed in any prevailing engines the movement of tumble is practiced. To have a complete combustion stimulated by the process of mixing air and fuel molecules with the observation at lower engine speed and better mixing is the Moto of research. The performance of the engine increase and complete combustion leads to reduced emission (CO, HC, and CO 2 ) and small change in volumetric efficiency. It is also proved that, increased tumble movement introduces aerofoil plate that helps the flame spread which used into constant heat transfer rate. This suggests to a new combustion technique that should be developed to yield improved primary combustion processes in-side the engine with slightly increase in the break thermal efficiency. DOI: http://dx.doi.org/10.5755/j01.mech.21.4.8685

Sliding mode controller of hydraulic generator regulating system based on the input/output feedback linearization method

An input/output feedback linearization method based sliding mode control strategy is proposed for the hydraulic generator regulating system (HGRS) with external disturbance and system uncertainties to enhance its response. Based on the input/output feedback linearization method, the relationship between reference output and control output is established. Then a sliding mode controller is designed to reject the influence of external disturbance and system uncertainties on the system performance and compelled the current dynamic output exponentially stabilized at their reference states. In order to eliminate the inherent harmful chattering phenomenon of sliding mode controller, a high-slope saturation function is used to replace the discontinuous sign function in the sliding mode manifold design. Several simulations with respect to the dynamic analysis of HGRS system without controller, fixed point stabilization, periodic orbit tracking and robustness test against random noises have been carried out to test the effectiveness of the proposed controller technique. The results show that the proposed sliding mode controller improves the nonlinear HGRS system performance with an accurate precision and a shorter time in all cases.

Design principles of natural light-harvesting as revealed by single molecule spectroscopy

Biology offers a boundless source of adaptation, innovation, and inspiration. A wide range of photosynthetic organisms exist that are capable of harvesting solar light in an exceptionally efficient way, using abundant and low-cost materials. These natural light-harvesting complexes consist of proteins that strongly bind a high density of chromophores to capture solar photons and rapidly transfer the excitation energy to the photochemical reaction centre. The amount of harvested light is also delicately tuned to the level of solar radiation to maintain a constant energy throughput at the reaction centre and avoid the accumulation of the products of charge separation. In this Review, recent developments in the understanding of light-harvesting by plants will be discussed, based on results obtained from single molecule spectroscopy studies. Three design principles of the main light-harvesting antenna of plants will be highlighted: (a) fine, photoactive control over the intrinsic protein disorder to efficiently use intrinsically available thermal energy dissipation mechanisms; (b) the design of the protein microenvironment of a low-energy chromophore dimer to control the amount of shade absorption; (c) the design of the exciton manifold to ensure efficient funneling of the harvested light to the terminal emitter cluster.

Optimization of flow distribution in flat plate solar thermal collectors with riser and header arrangements

The thermal performance of flat-plate solar collectors with riser and header arrangements is strongly influenced by the flow distribution through the absorber tubes. A more uniform flow distribution leads to a homogenous temperature distribution which gives higher collector efficiency. The Z distribution usually has better performance when compared to Π distribution. The design of the manifold influences the observed flow distribution. To optimize the manifold design, a correlation model was developed, based on correlations for minor pressure losses. Furthermore, the flow in this optimized geometry was simulated in 3D using the computational fluid dynamics (CFD) software code in order to confirm the results of the correlation based model. A new experimental low-intrusive technique was used to measure the flow distribution in an existing solar collector, validating the simulation results. The flow inside the absorber tubes is laminar; the major pressure loss inside riser tubes was measured using a high accuracy differential pressure transmitter, which then permits the indirect estimation of the mean velocity inside the tubes. It was the first time that this experimental methodology has been applied to analyse the flow distribution in solar collectors. The influence of the total water flow rate was analysed. For a good flow distribution it was concluded that the outlet header manifold should have a higher diameter compared to the inlet header diameter. Usually commercialised solar collectors have the headers with same diameter.