• Energy Research

The paper investigates hydraulic wave propagation phenomena through hydraulic circuits of power transmission systems by means of numerical approaches. The actuation circuit of a Dual-Clutch Transmission (DCT) power transmission system supplied by a Gerotor pump is analyzed. A steady state approach is adopted to detect resonance phenomena due to Gerotor design parameters and circuit lengths, while one-dimensional numerical models are implemented to predict the pressure oscillations through the hydraulic ducts for the whole pump operating domain. CFD-1D pipelines are adopted to address the pressure oscillation behavior through the hydraulic pipeline, while spectral maps and order tracking techniques are used to evaluate their fluctuation intensity in function of the pump speed rate. The numerical models are validated with experimental tests performed on an ad hoc test rig for power transmission systems and a good match is found between the numerical and the experimental results. Pump design parameters as well as hydraulic accumulators and resonators are numerically investigated to quantitatively evaluate their improvement on the circuits’ hydro-dynamic behavior. Furthermore, simplified numerical models are implemented to investigate the frequency response behavior of the hydraulic circuits by means of linear analysis. This approach resulted to be particularly effective for the prediction of the resonance frequencies location, and it can be adopted as an optimization tool since significant simulation time can be saved. Finally, the performance of the circuits operating with an eco-friendly fluid is evaluated numerically and the results are compared with the ones obtained with a traditional petroleum-based oil.

Abstract The paper focuses on the analysis of an industrial ceramic kiln in order to improve the energy efficiency and thus the fuel consumption as well as the pollutant 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. CFD simulation is also employed to determine the heat transfer coefficients between the tiles and the different components of the system. The numerical approach is used for analysing the effects of the exhaust gases recovery from a CHP turbine unit on the overall efficiency of the kiln. In particular, the CFD approach is adopted for investigating the best location for the hot gases injection within the pre-heating zone of the kiln. The influence of the exhaust gases on the heat exchange between the tiles and the air flow is addressed and the improvement on the convection heat transfer is determined. By means of the 0D/1D the behaviour of the entire kiln is evaluated with particular attention to the fuel consumption. The employment of the CHP exhausts recovery demonstrates to be beneficial both in terms of a reduction of the electric energy requirement of the system for powering the many blowers adopted and in terms of increased efficiency of the kiln.