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Distributed generation and sector coupling are key factors for economic decarbonization. Because gas networks have a large storage capacity, they have attracted the attention of power engineers to use them to increase the flexibility and security of supply in the presence of renewable and distributed energy resources. This paper makes the first attempt to integrate the electricity and gas systems to fill available gas storage facilities with synthetic natural gas on a large scale. This synthetic natural gas can then be used to operate gas turbines and to compensate for the fluctuating production of renewable energy sources. The LINK-holistic architecture, which integrates renewable and distributed energy resources, is used in this work. It facilitates sector coupling, which means power-to-gas and gas-to-power, throughout the entire power grid and at the customer level. This work is limited to investigating the power-to-gas process at the prosumer level. The electricity surplus of rooftop PVs is used to produce synthetic natural gas, fed into the gas grid after covering the local gas load. The behaviors of the electricity and gas grids are investigated. Results show that electricity prosumers may also become prosumers of synthetic natural gas. The current unidirectional gas grids should be upgraded with compressors at pressure reduction groups to turn them bidirectional, allowing synthetic natural gas storage in the existing large gas storage appliances after considering the pipes' linepack effect. The proposed solution could make it possible to fill the underground storage plants in summer, when the electricity and synthetic natural gas production exceed electrical and gas demand, respectively. [ABSTRACT FROM AUTHOR]

The removal of heat from electronic components, increasingly miniaturized with high power dissipation per unit volume, is a significant industrial problem to be resolved, to avoid failures due to excessive temperatures and besides to maintain performance and operating conditions. This article describes the development of a one-dimensional thermodynamic model to simulate the cooling of electronic chips belonging to inverters for stationary PV solar arrays; these are typically located in very different environments, including deserts or very hot areas, so the operating life of theirs inverter units are strongly affected by changes in external environmental conditions. Results have shown that the model allows, with very low calculation times, to quantify the effects of cooling performance and thermal load of electronics both in design and off-design conditions: the working temperature of the components was monitored as the effectiveness of the main heat exchanger vary with the exposure to the external environment over time, in terms of fouling and as the ambient air temperature changes; in this case a simple control system was simulated to limit the maximum temperature of the chips and the air flow rate of the fans. The thermal performances of two types of glycol-based refrigerant fluids have been compared.

Renewable energy systems (RES) are currently being deployed on a large scale to meet the ambitious sustainable development goals for the next decades. A higher penetration of sustainable means of power production passes through the diffusion of RES-based distributed energy systems. The hybridization of such systems and their integration with Energy Storage Systems (ESS) can help improve reliability and level the mismatch between power production and consumption. In this paper, a novel modular tool for the simulation of distributed energy systems is presented by means of its application to a case study. The considered system is composed by PV modules, ESS and heat pumps. The optimal sizing of the components for self-consumption has been obtained through an electricity production cost minimization. A comparison between two different configurations has been conducted: in the first case, the thermal load is completely satisfied by a natural gas-fired boiler, while in the latter case, part of the thermal load is satisfied by a heat pump. The results have highlighted the impact of ESS on the economics of distributed energy systems and how the investment in such systems, in conditions similar to the case study, can be more easily sustained if a share of the total energy consumption of the unit is shifted from the thermal to the electrical part.

The energy demand in healthcare and hospital premises has distinctive features. Due to specific constraints in terms of service continuity and indoor air quality, the demand is at a large extent constant during the day and throughout the year. Indeed, a healthcare facility must fulfil several different activities. Medical equipment needs electric energy, while the Heating, Ventilation and Air Conditioning systems require thermal energy. It is extremely difficult to define reference characteristics for the energy demand, since the proportions of the different consumptions are strongly connected with the specific activities/services carried out within each structure. The present work aims at analysing the energy demand of a healthcare facility located near Firenze (Italy). The energy demand has been analysed by means of the available documentation to get a basic knowledge of the expected consumption of each component of the facility. These data have been then correlated with information on the actual healthcare activity parameters (e.g. staff in service, medical services) and on weather conditions. As a result, the study led to the definition of the principal energy drivers that characterize the Healthcare Facility. The analysis procedure is thought of general interest for the community working in the field, representing a benchmark for the calibration of energy digital twins and a reference data set useful to carry out building energy efficiency optimization strategies.

The aim of the present paper is to investigate numerically the heat transfer within exhaust valves by considering the actual boundary conditions provided from an internal combustion engine at differentload and speed. For this purpose, the valve is subdivided into seven adequate subdivisions to better assess the effect of each engine parts, therefore, an average value of the transient heat transfer coefficient (HTC) and the adiabatic wall temperature (AWT) for each subdivisions are evaluated during one cycle. These two parameters are introduced as boundary condition in a FEM model. The simulations are done at diverse engine regime, and therefore, the trend of the real boundary condition in term of HTC and AWT are given versus engine speed at different load. The findings show that the HTC increases linearly with engine speed however, the AWT decrease slightly at partial load and increase in the case of full engine load. The obtained model is used to highlight the temperature map, which will certainly help to avoid any damage to the exhaust valve.