The paper focuses on the analysis of an industrial ceramic kiln in order to improve the energy efficiency and thus the fuel consumption and the corresponding carbon dioxide emissions. A lumped and distributed parameter model of the entire system is constructed to simulate the performance of the kiln under actual operating conditions. The model is able to predict accurately the temperature distribution along the different modules of the kiln and the operation of the many natural gas burners employed to provide the required thermal power. Furthermore, the temperature of the tiles is also simulated so that the quality of the final product can be addressed by the modelling. Numerical results are validated against experimental measurements carried out on a real ceramic kiln during regular production operations. The developed numerical model demonstrates to be an efficient tool for the investigation of different design solutions for the kiln's components. In addition, a number of control strategies for the system working conditions can be simulated and compared in order to define the best trade off in terms of fuel consumption and product quality. In particular, the paper analyzes the effect of a new burner type characterized by internal heat recovery capability aimed at improving the energy efficiency of the ceramic kiln. The fuel saving and the relating reduction of carbon dioxide emissions resulted in the order of 10% when compared to the standard burner.

In this paper some design aspects related to external gear pumps balancing surfaces are studied, and some useful guidelines for designing bearing blocks balancing surfaces are suggested. In order to study bearing blocks axial balance, a numerical procedure for the determination of the pressure distribution inside the clearance bounded by gears sides and bearing blocks internal surfaces is firstly presented and applied. After, the influence of bearing blocks geometry and pump operating conditions on the widening thrust is highlighted, considering both constant and variable lateral clearance heights. Then, the computations are performed to evaluate the widening thrust variation as a function of bearing blocks relative tilt with respect to gears lateral sides, and both positive and negative bearing blocks tilts are evidenced and discussed. Finally, the numerical procedure is validated through a comprehensive comparison of its results with experimental data (coming from some bibliographic sources), and some useful guidelines in designing external gear pumps balancing surfaces are defined.

The geometric complexity and high-pressure gradients that characterize the design of the flow field of gear pumps make it very difficult to obtain an accurate CFD simulation of the component. Usually, assumptions are made both in terms of geometrical features and physics being included in the analysis. The contact between the teeth, which is a key factor for the correct functioning of these pumps, represents a critical challenge in 3D CFD simulations, mainly due to the intrinsic limits of the dynamic meshing techniques that can hardly effectively manage a zero or close to zero gap point forming during gear rotation. The geometric complexity and high-pressure gradients that characterize the gear pump flow field make a CFD analysis quite difficult, and the contact between the gear teeth is usually avoided, thus being an extremely important feature. In this paper, a gear pump composed of inlet and outlet pipes was considered, and the contact between the gear’s teeth was modeled in two different ways, one where it is effectively implemented and one where it is avoided using distancing and a proper casing modification. Herein, a new methodology is proposed for the application of the dynamic mesh method in the Simcenter STAR-CCM+ environment using an adaptive remeshing technique. The proposed methodology is compared with the alternative overset meshing method available in the software. The new meshing method is implemented using a user-routing that reproduces the real geometry of the gears while rotating during the pump operation, with teeth contact included. The routine is optimized in order to limit the additional computation and time needed for the remeshing process. The results that can be obtained using the two meshing approaches for the gear pump are compared in terms of computational effort and the accuracy of the results. The two methods showed opposite results in almost all the reported results, with the overset being more precise in the radial pressure evaluation and the dynamic being more reliable in the cavitation/aeration extension cloud.

This paper wants to investigate the effects of eco-friendly fluids on the thermo-fluid-dynamic performance of external gear pumps in order to provide a first response to the increasingly urgent demands of the green economy. A computational fluid dynamics (CFD) approach based on the overset mesh technique was developed for the simulation of the full 3D geometry of an industrial pump, including all the characteristic leakages between components. A sensibility analysis of the numerical model with respect to different fluid properties was performed on a commonly used mineral oil, showing the key role of the fluid compressibility on the prediction of the pump volumetric efficiency. Moreover, the influence of temperature internal variations on both fluid density and viscosity were included. The BIOHYDRAN TMP 46 eco-friendly industrial oil and olive oil were further considered in this work, and the results of the simulations were compared for the three fluid configurations. A slightly lower volumetric efficiency was derived for the olive oil application against the other two conditions, but suggestive improvements were produced in terms of pressure and temperature distributions. Therefore, based on the obtained results, this paper encourages research activity towards the use of eco-friendly fluids in the hydraulic field.

The paper describes the influence of the fluid modeling on cavitation and aeration detection in external gear pumps and motors inter-teeth volumes during the gears meshing process, in order to compare the results coming from the use of different physical models of air release/adsorption and cavitation. A simplified cavitation model is firstly involved, and pressure transients are calculated imposing a pressure cut when the fluid vapor pressure (or the dissolved air partial pressure) is reached. After, assuming an equivalent approach able to involve the vapor phase generation, the cavitation phenomena in the meshing volumes are deepened, and the influence of the fluid modeling enhancement on the cavitating machine behavior is highlighted. Then, the equivalent fluid approach is enhanced introducing the air release, and properly coupling the gaseous phases release/adsorption to the Henry's Law for not instantaneous processes. Finally, the influence of the air release/adsorption time constant on meshing volumes pressure transients are detailed, with particular attention devoted to the modification introduced by the cavitation detailing on the gaseous phase void fraction determination and on the angular extension of the cavitation phenomena detection.