This paper investigates the thermal performance of thermoacoustic heat exchangers subjected to acoustically oscillating flows. The analysis is carried out by experimental measurements of the heat fluxes sustained by the ambient heat exchanger of a prime mover of the standing wave type. A home-made parallel-plate heat exchanger is considered for the study. The gas-side convection heat transfer coefficients expressed as Nusselt numbers are determined over a wide range of velocity amplitudes of the oscillating flow. The experimental results are then compared to the predictions of a number of theoretical models currently applied in thermoacoustics such as the time-average steady-flow equivalent (TASFE) model, the root mean square Reynolds number (RMS-Re) model, and the boundary layer conduction model. The comparison suggests that the boundary layer model performs better than the rms-Re and TASFE models in predicting the heat transfer coefficients in oscillating flows. The relative difference between the model predictions and the experimental data amounts to 19%. A new correlation law, based on regression of the experimental data, is also proposed.

Noise pollution is by now worldwide recognized as a major problem for the quality of life in urban areas. Noise effects include various impacts on mental and physical health and disturbance of daily activities (may affect sleep, conversation, lead to perception of annoyance, cause hearing loss, cardiovascular problems as well as affect task performance) [1-3].Then, assessing the problem and programming actions for controlling its adverse effects have become issues of immediate concern for community as evidenced by the large number of anti-noise laws, ordinances and regulations decreed by many governments [4-6]. Also, the EU legislation on environmental noise [7] requires the drawing up of noise maps around main transport infrastructure and in major agglomerations to provide estimates of noise exposure and, where necessary, to work out noise abatement action plans. This paper presents the results of a comparison between the data collected in a previous study of the authors on the environmental noise pollution of the city of Messina (Italy), with the simulated data through the most tested forecasting models in the scientific world. They have been verified the data both by simulation from the models and those obtained experimentally in the same points, after the construction of the works carried out in the city of Messina, consisting of the construction of a motorway junction and a new maritime landing in the southern part of the City. The interventions carried out have significantly modified the vehicular traffic of the urban center, and to verify the effects, comparisons were made with the values measured in the same 35 sites previously surveyed. The comparison was made using simulated values and experimental measurements of the main noise pollution indices (Leq, L1, L10, L50, L90, L99) and of the traffic flow and composition.

The microclimatic control of the environments destined to the exposure and the conservation of the works, understood as control of the parameters of temperature, relative humidity, lighting engineering, and air quality inside both macro-environments (exhibition halls, warehouses, etc.) and of museum micro-environments; (shop windows, storage and transport containers), has long been of particular interest to museum curators. It is well known that the environmental parameters mentioned above can triggering or aggravating degradation processes through chemical, physical or biological mechanisms and how they contribute to increase or reduce the "life expectancy" of a cultural asset. This article shows the first results of a survey aimed at evaluate the conditions of the thermo-hygrometric and luminous microclimate for the conservation of works of art within the new seat of the Regional Museum of Messina. In this preliminary phase of a larger study, a simulation was conducted through a software to verify the main parameters of the passive behavior of the museum shell, in order to plan a subsequent campaign of investigations and measures on the compatibility of the microclimate with the regulatory requirements of the conservation of works of art and their use by the public and to provide information on possible adjustments plant engineering, also identifying techniques and solutions for the containment of energy consumption, always high in this type of structures.