Dehumidification Analysis of Rotary Solid Desiccant Wheel & Packed Bed System

Moisture transport is one of the major challenges in desiccant dehumidification. The transfer of moisture basically involves transfer of heat between moist air and desiccant particles as well as the mass transferal of moisture between moist air and desiccant particles. Type of desiccant dehumidification analysis is heating with dehumidification. Warmth move between sodden air and desiccants likewise gains consideration since temperature appropriation significantly influences the mass exchange execution through desiccant isotherms. The warmth and mass exchange between a clammy air stream and desiccant particles is dissected. Surface dissemination is noticed to overwhelm mass exchange within the silica gel particles. Here in this paper, we have compared the three diffusion coefficients Ordinary, Knudson and surface diffusion both for packed bed system and rotary desiccant system. Also, two models of move coefficients are introduced here and analyzed. Pseudo gas side controlled model usages an observational gas side mass exchange coefficient to represent dissemination opposition on strong side. Solid side resistance model settles the dissemination condition and is the finest exact as far as move coefficients. Notwithstanding, it makes examination considerably more clear.

A Method to Determine Stress-Dependent Filtration Properties of Fractured Porous Rocks by Laboratory Test Data

Within the dual porosity model the authors develop and theoretically, using synthetic data, substantiate the method for determining mass exchange coefficient and stress-dependent permeability of fractured porous reservoir rocks. The proposed filtration test circuit consists of three sequential measurements of flowrate in a specimen subjected to the varied external stress σ at the inlet fluid pressure P: by standard scheme (Q0) and with plugging of fissures at one (Q1) and at the other end (Q2) of the specimen. The model of the experiment is created, and the analytical solution is obtained for the direct problem on steady-state flow: dependences of Q0, Q1 and Q2 on σ and P. The input data are synthesized by superimposition of multiplicative noise on the exact solution of the direct problem. The synthesized data are used to derive the inversion relations for calculating the permeabilities k1 and k2 of fissures and matrix as well as the mass exchange coefficient by Q0, Q1 and Q2. Using LS method, the dependences k1(σ) and k2(σ) are reconstructed. The numerical experiments reveal low stability of inversion by input data. Thus, it is necessary to perform a cycle of measurements at the increasing input pressure with subsequent averaging of the results.

Parameterisation of physically based solute transport models in sandy soils

Immobile water fractions of up to 40% had been reported in sands, and it was therefore relevant to determine if the convection-dispersion equation (CDE) or mobile-immobile model (MIM) should be used as the basic physical model for field studies of solute transport in sandy soils. A review of literature data for granular media indicated that for steady state flow, the dispersion coefficient could be estimated from the grain Peclét number and the mass exchange coefficient from the pore water velocity, but the immobile water fraction was poorly predicted from soil properties.In this study, performed on a sandy soil at Moora, Western Australia, the choice of model was determined after analysis of column effluent breakthrough curves (BTC), sequential tracer experiments, and single tracer experiments on the same core. The latter two methods have recently been introduced in an attempt to independently measure some of the MIM parameters (immobile water content and mass transfer exchange coefficient) in situ. Low immobile water content was found in this sand, with very rapid exchange between the mobile and immobile regions. All 3 techniques gave measured immobile water contents around 10%, which was consistent with most literature values for granular media. The single tracer experiment does not give the mass exchange coefficient α (h–1), but α determined by the sequential tracer technique could not be confirmed by the BTC technique due to the wide 95% confidence interval of the fitted parameter. Although the MIM behaviour was minor and inconsistent in the Moora sand, the choice of model may depend on the problem under consideration. For short column experiments, the CDE and MIM produced similar solute transport behaviour. However, for leaching below the root-zone, the MIM is recommended.