- The influence of multi-hole orifice flow meter geometry parameters on the parameters of Newtonian fluid through multi-hole orifice meters was investigated using computational fluid dynamics as well as the effect of contamination in front of the MHO flow meter. The air flow was steady, three-dimensional, and turbulent. Analysed Newtonian fluid was air and physical properties that were considered were density and dynamic viscosity. The numerical method was finite volume method, and standard k-ε turbulence model was used for turbulence modelling. Multi-hole orifice meter with thre e different β parameters 0.5 5, 0.6 and 0.7, was observed and Reynold’s number was 10 5 . The pressure drop and discharge coefficient were analysed. Numerical simulations were performed using commercial software the STAR-CCM+ 2019.2. It was found that increase in 𝛽𝛽 parameter results with the decrease in pressure drop and increase in discharge coefficient. Also, it was found that that the influence of 𝛽𝛽 parameter is much higher when analyzing pressure drop rather than discharge coefficient values. Numerical simulations were also performed to investigate the effect of contaminations in front of the MHO plate with 𝛽𝛽 = 0.5, on the discharge coefficients. It was found that as the contamination angle is increased the discharge coefficient tends to increase.

Drying of textiles in industrial facilities represents an energy-intensive process where a large number of measures for energy and production cost savings can be introduced. Typical measures include the introduction of energy management, waste-heat recovery, process optimization and so on. Drying is a complex process with coupled heat and mass transfer between the heated air and humid textile, where parameters such as the air flow rate, air velocity and its flow regime and textile velocity and water content represent significant influential factors. The distribution of air temperature and density inside the drying section of an industrial stenter frame is analyzed in detail using three-dimensional numerical simulation, where the textile is modeled as a porous medium to analyze moisture diffusion within the textile. Heated air is introduced into a chamber by inlet nozzles and removed by exit nozzles, the distribution of which is based on actual machine configuration. A humid textile is introduced into a section, where temperature and density distribution within the textile are calculated for selected time periods. During the simulation in the Fluent program, models of specific component transport, multiphase air flow, turbulent flow, porosity and evaporation were used. The results represent a valuable data set that provides an in-depth insight into the drying process in the industrial stenter machine.

The heat transfer performances of ionic liquids [C4mpyrr][NTf2] and ionanofluids with Al2O3 nanoparticles under a laminar flow regime, and with constant heat flux on the tube wall is numerically modeled and analyzed for three values of initial/inlet temperature and for two Reynolds numbers. Heat transfer characteristics were considered by analyzing the temperature distribution along the upper wall, as well as by analyzing the Nusselt number and heat transfer coefficient. The results obtained numerically were validated using Shah’s equation for ionic liquid. Thermophysical properties were temperature-dependent, and obtained by curve-fitting the experimental values of the thermophysical properties. Furthermore, the same set of results was calculated for the ionic liquid and ionanofluids with constant thermophysical properties. It is concluded that the assumption that thermophysical properties are constant has a significant influence on the heat transfer performance parameters of both ionic liquid and ionanofluids, and therefore such assumptions should not be made in research.

The aim of this article is to determine the contamination influence on the parameters of gas flow through multihole orifice (MHO) meter. The numerical investigations of the contamination influence for the MHO flow meters have not been reported in the previous researches. The air flow was steady, 3-D, and turbulent. The finite volume method was used for the purpose of numerical analyses. The main considered physical properties of air were density and dynamic viscosity. The standard $k-\varepsilon $ turbulence model was used. MHO meter with two different $\beta $ parameters was observed. Also, the influence of contamination formed in front of the MHO meter with the same $\beta $ parameters was analyzed. In order to qualitatively analyze the influence of the contamination, the 15 different combinations of contamination parameters for seven different Reynolds numbers were analyzed. The pressure drop, singular pressure loss coefficient, and discharge coefficient were analyzed. The grid sensitivity study was performed on four systematically refined numerical grids for MHO meter without contamination and the results were compared with the experimental results found in the literature. Also, the grid refinement was done for MHO meter with contamination for two different values of Reynolds number. It was found that for the same values of contamination angle, regardless of the contamination parameters ratio, the results were unchanged. Also, it was found that the contamination has an influence on the change of pressure drop values, which directly affects the change of other parameters. Pressure drop and singular pressure loss coefficient of the orifice with contamination are smaller compared to the values for a pure orifice, whereby the measurement accuracy was reduced. Also, for cases of contamination, the discharge coefficient was increased, leading to a negative measurement error. It was found that the same trend occurs regardless of the Reynolds number. It was found that the MHO meter was less sensitive to the pressure drop changes due to the increase of contamination angle in regard to the single-hole orifice meters.

ABSTRACT A mathematical model which can describe flows of a number of immiscible fluids at high temperatures, where the radiative heat transfer cannot be neglected, is presented. It combines an interface-capturing multiphase model and the P-1 radiation model chosen for its simplicity. A finite volume method is utilized to discretize the governing equations and the solution methodology is based on the SIMPLE algorithm. The model implementation is verified on a number of simple problems. The numerical experiments show a good agreement with analytical solutions or results which could be found in literature. A cooling of a gas–liquid system inside a rotating tank is also simulated. The results show that a coupled modeling of the motion of a number of fluids and all fundamental modes of heat transfer are important. Neglecting the convective transport and resulting redistribution of phases, or neglecting the radiative heat transfer, could result in significant modeling errors.

When a finite volume method is used to solve equations of mathematical physics there are several factors which could influence the discretization error. The standard techniques for determining the order of a discretization schemes assume that numerical meshes have some idealized properties. However, meshes typically used in numerical simulations are characterized with a significant aspect ratios and non-orthogonality of discretization elements. The paper presents a methodology which could be used to analyze the influence of certain mesh properties on the order of a finite volume discretization. The methodology is used to study the influence of mesh uniformity and orthogonality on the accuracy of the gradient approximations based on Gauss method, Gauss method with corrections and a least square method.