Search

The replacement of LPG (liquefied petroleum gas) boilers with air-to-water heat pumps on an industrial site is proposed. The boilers are used to produce hot water for the heating of two workshops and for the manufacturing process (test benches). The substitution aims to improve the local air quality in terms of pollutant emissions. The energy benefits in terms of reduction of primary energy and CO2 emissions are analysed. The reduction in primary energy consumption varies between 51% and 64% for two different scenarios that are evaluated, respectively, under design and real operating conditions; the latter is based on the trend in heat loads and outdoor air temperatures recorded in a small town of central Italy in the year 2022. The results also show a decrease in CO2 production of between 58% and 68%. This replacement, carried out in a manufacturing context, represents a case study that may also be applied to industrial suburban areas of cities. [ABSTRACT FROM AUTHOR]

In a previous work, a significant contribution to urban air pollution, related to fuel-fired heating systems, was recorded. Thus, the replacement of existing boilers for space heating and domestic hot water (DHW) production systems with high-temperature air/water heat pumps (which can operate with radiators, the most common terminals in the existing building stock), is proposed for the improvement of the urban air quality. Scenarios of substitution within the entire residential building stock of two Italian cities, Milan and Salerno, belonging to different climate zones and with their own thermophysical characteristics, were analyzed. For each of them, the consequences of the replacement intervention on emission reduction, primary energy savings and lower CO2 production were evaluated. The results show that reduction of primary energy consumption, evaluated at design outdoor temperature and for the present generation mix, varied between 34% and 54% in Milan and between 43% and 60% in Salerno, for two values of renewable fraction in electricity generation. The reduction of CO2 production was in the range 30–52% in Milan and 39–58% in Salerno, respectively. The only unfavorable case occurred for Milan for a completely non-renewable electricity generation scenario. The replacement intervention, which implies a significant decrease of emissions of pollutants in urban areas, is unobtrusive to citizens, since the heat pumps (HPs) are coupled with current radiators, without the internal distribution system being modified. [ABSTRACT FROM AUTHOR]

In this paper, two methods for flux linkage regulation in a starter/alternator with an axial-flux permanent magnet (AFPM) machine are proposed and compared. Desired regulation is achieved by two different mechanical solutions, each of them capable of modifying the amount of flux linkage through displacement of the two rotors in the AFPM machine. Constant power generation is thus achieved with very inexpensive devices that do not require external energy sources since energy in the airgap doesn't change. The main difference between the two proposed solutions is that the speed dependant device is ideally a constant voltage source while the torque-dependant device behaves as a constant current source. Even if some improvements are still needed, both devices introduce the totally innovative concept of mechanical flux weakening for AFPM power regulation in a wide speed range. Finally, the paper demonstrates that the introduction of these devices doesn't modify machine behavior in starting mode, so that the particular features of AFPM machines in terms of high toque density and overload capability remain unaffected. Index Terms--Axial-flux permanent magnet (AFPM).

An ac brushless drive in which Hall-effect sensors are used as rotor position sensors is presented in this paper. Three different methods to obtain a high-resolution position estimation from the low-resolution sensors are described and compared through simulation and experimental testing. The proposed control algorithm's most innovative feature is its adaptability to the entire speed range, including startup, when using any of the three estimation algorithms. The control algorithm has been implemented and tested in order to drive a slotless axial-flux permanent-magnet (PM) machine for domestic appliance applications. [ABSTRACT FROM AUTHOR]