Biologically-inspired propulsion systems are currently receiving significant interest in the engineering applications. Motivated by these developments, in the present article analysed heat and mass ...transfer with the transverse magnetic field on peristaltic motion of two-phase flow (particle-fluid suspension) through a planar channel have been examined. The flow is observed under the influence of electric field and chemical reaction. The present flow problem is modeled using lubrication theory approximation and also with a combination of long wavelength and creeping flow regime assumptions. Moreover, the problem is further simplified using Debye linearization. Analytical solutions are obtained for the resulting coupled ordinary differential equations. The influence of various emerging parameters is discussed for velocity, temperature and concentration profile. Furthermore, the behavior of pressure rise is also discussed to analyse the pumping characteristics. Trapping mechanism is also presented with the help of streamlines. It is observed that velocity distribution tends to increase significantly due to the greater effect of electric field and electro-osmotic parameter, however, magnetic field and particle volume fraction provides a marked resistance to the flow. The influence of electric field and electro-osmotic parameter depicts converse behavior on temperature and concentration distribution. Furthermore, chemical reaction parameter causes a significant reduction in the concentration distribution. The main motivation of the present study is due to such fact that two-phase flow process is very important to analyse the peristaltic muscular expansion and contraction in propagating various biological fluids that act like a particle-fluid mixture. The present study has a wide range of applications in bio-medical engineering i.e. electromagnetic peristaltic micro pumps.
•Heat and mass transfer with transverse magnetic field is studied.•Exact solution are presented for fluid phase and particle phase.•EDL effect is also taken into account.•The non-Newtonian Jeffrey fluid is modeled with two phase phenomena.•Numerical integration is used to obtain the expression for pressure rise.
Analysis are made to find the heat transfer characteristics and skin friction for two-dimensional oblique stagnation point flow of SWCNTs and MWCNTs based nanofluid flowing over a curved surface. ...Similarity transformations convert the governing flow field equations into a pair of non-linear ordinary differential equations, and then they are numerically solved through bvp4c function in MATLAB. The inspection of the obtained result reveals that SWCNTs based nanofluid have comparatively higher rate of heat transfer and skin friction then MWCNTs based nanofluid, which are due to their dissimilar values of densities. Moreover, in the case of flat surface (K = ∞) maximum amount of heat is transferred compared to the curved surface. The velocity distribution tends to decrease as we approach from curved to flat surface. Further, the Nusselt number provides higher values for SWCNTs case when solid fraction of nanoparticles enhances. Finally, the comparison of the current numerical results with the published literature in a limiting case is given and found to be in an excellent agreement.
This article gives an overview of the background-oriented schlieren (BOS) technique, typical applications and literature in the field. BOS is an optical density visualization technique, belonging to ...the same family as schlieren photography, shadowgraphy or interferometry. In contrast to these older techniques, BOS uses correlation techniques on a background dot pattern to quantitatively characterize compressible and thermal flows with good spatial and temporal resolution. The main advantages of this technique, the experimental simplicity and the robustness of correlation-based digital analysis, mean that it is widely used, and variant versions are reviewed in the article. The advantages of each variant are reviewed, and further literature is provided for the reader.
•The cooler had a complex heat & mass exchanger with an advanced wet material layer.•Intermittent water supply scheme was implemented.•The cooler achieved 100–160% higher COP compared to the existing ...dew point coolers.•Electricity use of the cooler was reduced by 50–70% compared to existing dew coolers.•This optimal working air ratio was 0.364 that enabled maximised cooling effectiveness.
This paper presents an experimental investigation of a super performance dew point air cooler which, by employing a super performance wet material layer, innovative heat and mass exchanger and intermittent water supply scheme, has achieved a significantly higher energy efficiency (i.e. Coefficient of Performance, COP) and a much lower electrical energy use compared to the existing air coolers of the same type. This involves the dedicated system design & construction, fully planned experimental testing under various simulated climatic conditions representing the climate of hot & dry, warm & dry, moderate, warm & humid and standard lab testing condition, testing results analysis and discussion, as well as the parallel comparison against the commercial dew point air cooler. Under the standard test condition, i.e. dry bulb temperature of 37.8°C and coincident wet bulb temperature of 21.1°C, the prototype cooler achieved the wet-bulb cooling effectiveness of 114% and dew-point cooling effectiveness of 75%, yielding a significantly high COP value of 52.5 at the optimal working air ratio of 0.364. The testing also indicated that the lower inlet air relative humidity led to a higher cooling efficiency, while the lower cooling output helped increase COP and cooling effectiveness (including the wet-bulb effectiveness and dew-point effectiveness) of the cooler.
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•Sorption enhanced steam methane reforming in bubbling fluidized reformer is simulated.•Dolomite distribute in the upper region, while catalyst concentrate in the lower region.•Heat ...transfer coefficient of two types of particles positively correlates with slip velocity.•Superficial gas velocity positively affects CH4 and H2O but negatively affects CO and H2.
The hydrodynamics and thermochemical characteristics of the sorption enhanced steam methane reforming process in a fluidized bed reactor are studied with a multiphase particle-in-cell model, featuring steam methane reforming and CaO carbonation reaction kinetics. After model validation, the high-fidelity information of solid phase at the particle-scale level is presented with the discussion of the effects of several critical operating parameters on the gas thermal properties. The results show that bubble evolution leads to bed expansion and the density-segregation mechanism causes the elutriation of dolomite particles. The highest velocity and Reynolds number of particles are observed around the bubble, and the magnitudes of these variables are higher than that in the dense region. The heat transfer coefficients (HTC) of Ni-catalyst and dolomite particles range from 100 W/(m2·K) to 600 W/(m2·K), which increase with the slip velocity and Reynolds number but decrease with solid volume fraction. The time-averaged particle dispersion coefficient in × , y, and z directions for the Ni-catalyst particles are 1.63 × 10-4, 1.82 × 10-4, and 9.92 × 10-4 m2/s, respectively while for the dolomite particles are 2.17 × 10-4, 2.52 × 10-4, and 1.3 × 10-3 m2/s, respectively. The temperature of bubbles near the wall is lower than that in the core region. Superficial gas velocity shows a positive effect on CH4 and H2O, gas temperature, and gas density while a negative effect on CO and H2, gas specific heat capacity. Bed temperature significantly influences the gas properties and gas product yields due to its intrinsic relation with chemical reactions. Ni-catalyst particle diameter performs an insignificant impact on the thermochemical characteristics in the bed.
An investigation is made to study the micropolar fluid flow of transient thermophoretic particle deposition of forced convective unsteady heat and mass transfer flow due to a rotating disk in the ...presence of uniform magnetic field. The governing nonlinear partial differential equations are transformed using similarity transformation and the numerical methods are discussed using Nachtsheim-Swigert shooting iteration technique along with sixth-order Runge-Kutta integration scheme. The obtained results show that the Nusselt number increases with an increase in the unsteadiness parameter. The results also show that micro-rotational tangential velocity decreases with the increase of the magnetic parameter.
•Methods for the capture of gas-liquid interface were summarized.•Mass transfer models for the calculation of interfacial source terms were reviewed.•Falling film components during absorption, ...desalination and evaporation were concerned.•CFD simulation studies on falling film components were reviewed.
Falling film driven by gravity finds wide application in various industry areas, such as refrigeration, chemical engineering and desalination. The liquid film flows along the solid wall and gets contact with the gas phase, and heat and mass transfer occur due to the temperature and concentration gradients. To get the detailed profiles of flow, temperature and concentration and to explore the transport mechanism of falling film multiphase flow, researchers have adopted the Computational Fluid Dynamics (CFD) method for different attempts. The present review gives a comprehensive summarization of the CFD simulation work aided by the commercial software or in-house code concerning the coupled hydrodynamic, heat and mass transfer characteristics in falling film components, including the fields of carbon dioxide capture/chemical absorption, distillation/desalination and evaporation/condensation. The mathematical foundation for the description of falling film flow was introduced firstly. After the presentation of different mass transfer models for the calculation of interfacial heat and mass transfer source term, the previous CFD simulation studies on the abovementioned fields were reviewed respectively. Finally, some conclusive remarks were stated and suggestions for future work were given as well. The present review provides a comprehensive and meaningful guidance for the CFD simulation of falling film flow in various industry application fields.
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