Sergio Marinetti

This paper presents a reversible heat pump based on CO₂ as the refrigerant, able to provide heating, cooling, and domestic hot water to high energy demand buildings. The unit was developed and tested under the EU H2020 project MultiPACK, which has the main goal of assuring the market about the feasibility, reliability, and energy efficiency of CO₂ integrated systems for heating and cooling and promoting a fast transition to low environmental impact solutions. Within the project, the confidence raising was performed by installation and monitoring of fully integrated state-of-the art CO₂ systems in the Southern European Climate. With the aim of predicting the unit behaviour under variable load and boundary conditions, a dynamic model of the entire unit was developed with commercial software, considering actual components and the implemented control system and it was validated with experimental data, collected at the factory’s lab before commissioning. The validation against experimental data collected during operation as a heat pump demonstrated a maximum percentage difference between the experimental and predicted value of gas–cooler heat flow rate equal to +5.0%. A preliminary comparison with the experimental data in chiller configuration is reported, however further development was required to achieve a satisfactory validation. Lastly, the numerical model was utilized to simulate a typical operation in heat pump configuration with the system coupled with a hot water tank storage for the production of domestic hot water and space heating; the model predicts higher COP when operating in domestic hot water operation due to the lower water inlet temperature.

The operating theater is the environment inside the hospital that requires the greatest deal of attention in the choice of the devices for air supply, diffusion and recovery. The design of Heating, Ventilation and Air Conditioning (HVAC) systems dedicated to these environment plays a crucial role to drastically reduce the risk of infection for patients, in addition to the maintenance of adequate thermo-hygrometric comfort conditions for the medical team. As a result, a lower risk of sepsis has been reported thanks to a cleaner air injection in operating theaters. In this work, the authors have reproduced numerically the air distribution inside an operating theater, where a swirl diffuser system is present. The numerical results have been validated against the experimental data obtained during field campaign. The objective of the present work is to develop an effective and robust numerical model able to reproduce the fluid dynamics phenomena inside operating theaters.

The operating theater is the environment inside the hospital that requires the greatest deal of attention in the choice of the devices for air supply, diffusion and recovery. The design of Heating, Ventilation and Air Conditioning (HVAC) systems dedicated to these environment plays a crucial role to drastically reduce the risk of infection for patients, in addition to the maintenance of adequate thermo-hygrometric comfort conditions for the medical team. As a result, a lower risk of sepsis has been reported thanks to a cleaner air injection in operating theaters. In this work, the authors have reproduced numerically the air distribution inside an operating theater, where a swirl diffuser system is present. The numerical results have been validated against the experimental data obtained during field campaign. The objective of the present work is to develop an effective and robust numerical model able to reproduce the fluid dynamics phenomena inside operating theaters.

IR thermography has been widely used to measure air temperature in many application fields. Usually screens or targets are located in the region of interest in such a way to minimise the perturbation of the flow under investigation. In this work, this technique is applied to map the air distribution inside the cold curtain of an open refrigerated display cabinet. The performances of a black cardboard, which is commonly used, and a net-screen are studied in different conditions by a computational fluid dynamics analysis. Experimental measurements are carried out on the cold curtain, both with the cardboard and the net-screen. The comparison of results is reported. The analysis shows that this measurement technique is highly intrusive from the fluid-dynamic point of view, and the error due to the surrounding radiation is significant.