In this study, we present a method for prediction of the drug-release profile based on the physical mechanisms that can intervene in drug release from a drug-carrier. The application presented here incorporates the effects of drug concentration and Reynolds number defining the circulating flow in the testing vein. The experimental data used relate to the release of diclofenac from samples of non-degradable polyurethane subjected to static and continuous flow. This case includes simultaneously three mechanisms: burst-release, diffusion and osmotic pressure, identified beforehand here as being able to contribute to the drug liberation. For this purpose, authors coded the Sequential Quadratic Programming Algorithm to solve the problem of non-linear optimization. The experimental data used to develop the mathematical model obtained from release studies carried out in water solution at 37 °C, for three concentrations of diclofenac and two water flow rates. We discuss the contribution of mechanisms and kinetics by considering two aforementioned parameters and, following that, we obtain the specific-model and compare the calculated results with the experimental results for the reserved cases. The results showed that drug percentage mostly affect the burst release, however flow rate has affected the osmotic release. In addition, release kinetics of all the mechanisms have increased by increasing the values of two considered parameters.
The MPBL is an effective technology in terms of heat flow transport capacity: 10 MW.m, [2],with high level adaptability. A bond graph model of such a system is proposed in this paper. The model is dynamic, qualitative, configurable and pays particular attention to the dynamic of the transient regime. It aims at being a tool dedicated to designing the different components of a MPBL. It is also used for a physical analysis of the system in different operating conditions.
This article is devoted to the dynamic study of a brazed plate heat exchanger (BPHE). First, is proposed an introduction to the industrial context of the current FUI THERMOFLUIDE project. A succinct presentation of the heat exchanger technology is proposed. Afterward, is given a state of the art about BPHEs modeling, heat transfer and pressure drop correlations. Then a detailed mathematical description of an original dynamic model is presented. The last section deals with a description of the experimental test rig and performed validation tests.
International audienceThe main purpose of the project FUI THERMOFLUID is to study the feasibility of a new electronic cooling system embedded on flying objects (missile, satellite, and airplane). The technology chosen consists of a pumped two-phase flow cooling loop (PTPFL). It is an innovativetechnology with a transport capacity of the thermal power up to 10 MW.m, exceeding in this way the performance of all other technologies. A PTPFL is a cooling loop based on the exploitation of the latent heat properties of the fluid trapped inside the loop, and moved by a pump. The components constituting a PTPFL are: a two-phase reservoir (TP-R), a mini-channels evaporator, a brazed plate condenser, a pump, and pipes.The global research work is devoted to propose a dynamic model and experimental validation of the PTPFL. The present article is exclusivelydedicated to the TP-R. Indeed, this element plays a key role in the functioning of PTPFL. Historically, the TP-R did not equip the first coolingloop. However, due to its advantages, its introduction was essential. The developed dynamic model will be used in another work to predict thethermal hydraulic efficiency of the PTPFL from its mechanical and fluidic parameters, to conduct the study of transitional regimes and instabilityproblems, and provides an original tool dedicated to design the TP-R in function of the thermal power levels to be evacuated and the selectedrefrigerant. The bond graph methodology is adopted for modelling works because of its energetic approach and multi-physics character ofthe studied system. The new model proposed in this article has many originalities: First, it is based on bond graph approach. Nowadays, theopen literature shows that no bond graph model has been developed for such thermo-fluid system. Second, the dynamic model of TP-R paysgreat attention to phenomena that have never been taken into account in works cited in the present article, such as evaporation and condensation.Third, different conducto-convective heat exchanges are modelled without any experimental recalibration of the thermal exchange coefficients,unlike models proposed in the literature. In fact, all coefficients are systematically calculated using adequate correlations
This document deals with the design of a Permanent Magnet Synchronous Motor (PMSM) to peripherally drive a counter-rotating pump inducer. The motor/pump is associated using a rim-driven principle where the motor’s active parts are located at the periphery of the inducer blades. It proposes using a Halbach array of permanent magnets for the active rotor of the motor. This solution allows the generation of a Sinusoidal Electromotive Force (EMF). Therefore, a more stable electromagnetic torque is reached. An optimum geometry suitable for the inducer specifications while respecting operational constraints is determined. The obtained geometry is then simulated using the Finite Element Method. The results are satisfactory in terms of average torque and EMF waveform. Use of the Halbach array allows a significant improvement of the flux density in the air gap compared to a designed surface-mounted machine. The experimental validation will be performed once the prototype is realized in the Laboratory of Fluid Engineering and Energy systems (LISFE).
The inducers increase the pressure available at the inlet of the impellers of centrifugal pumps. This technological solution may induce instabilities, such as pre-rotating flow at partial flow rates. The scientific literature offers studies on the cavitation in the inducers, as well as on the associated instabilities. However, studies describing devices that improve the behavior in these unstable regimes are rare. This is particularly true for fluids like aviation fuels or liquids with dissolved gases. In the present work we expose, an experimental study for two axial inducers carried out at low flow rates in cavitating and non-cavitating regimes in a closed loop equipped with a transparent test pipe. The working liquid is water with and without dissolved CO2. We employ a camera and a high-speed camera to take the photographs of the dynamics of the cavitation structures. The experimental campaign provided results of head breakdown comparison. The added dissolved CO2 gas at a concentration of 300 mg/L does not change the overall inducers' performance in non-cavitating regime. The paper presents also the impact of some of inducers' geometrical parameters on their cavitating performance. The authors observed pre-rotating flow instability, which they tried to decrease by incorporating a grooved ring into the inlet side of the inducers. It is found that pre-rotating structures are much less developed in the upstream when a grooved ring is employed.
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