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Dynamic energy modelling of buildings is a key factor for developing new strategies for energy management and consumption reduction. For this reason, the EnergyPlus software was used to model a near-zero energy building (Smart Energy Buildings, SEB) located in Savona, Italy. In particular, the focus of the present paper concerns the modeling of the ground source water-to-water heat pump (WHP) and the air-to-air heat pump (AHP) installed in the SEB building. To model the WHP in EnergyPlus, the Curve Fit Method was selected. Starting from manufacturer data, this model allows to estimate the COP of the HP for different temperature working conditions. The procedure was extended to the AHP. This unit is a part of the air-handling unit and it is working as a heat recovery system. The results obtained show that the HP performance in EnergyPlus can closely follow manufacturer data if proper input recasting is performed for EnergyPlus simulations. The present paper clarifies a long series of missed information on EnergyPlus reference sources and allows the huge amount of EnergyPlus users to properly and consciously run simulations, especially when unconventional heat pumps are present.

Geothermal piles are a very promising technique to exploit the low enthalpy resource for ground coupled heat pumps. In fact, they are heat exchangers integrated in the foundation structures of the buildings, with reduced need in term of ground surface availability and diminished drilling costs. Unfortunately, to evaluate the ground thermal response to their presence it is not possible to use classical analytical solutions due to their low aspect ratio and to the relevant effect of the heat capacity of the inner cylindrical volume. In addition, different shapes of the pipe arrangement are possible: helix around the foundation pile or a series of vertical pipes connected through U bends at top and bottom of the cylindrical volume. This study proposes a semi-analytical method to model ground heat exchangers with a great flexibility concerning their shape. The method, called Multiple Point Sources (MPS), applies the spatial superposition of the analytical solution for the Single Point Source. It has been validated by means of the comparison with literature analytical methods and FEM results for helix heat exchangers. Finally, it has been applied to find the temperature response factor for different shapes of heat exchanger in geothermal piles.

Liquefied Natural Gas (LNG) is a crucial resource to reduce the environmental impact of fossil-fueled vehicles, especially with regards to maritime transport, where LNG is increasingly used for ship bunkering. The present paper gives insights on how the installation of LNG tanks inside harbors can be capitalized to increase the energy efficiency of port cities and reduce GHG emissions. To this purpose, a novel integrated energy system is introduced. The Boil Off Gas (BOG) from LNG tanks is exploited in a combined plant, where heat and power are produced by a regenerated gas turbine cycle; at the same time, cold exergy from LNG regasification contributes to an increase in the efficiency of a vapor compression refrigeration cycle. In the paper, the integrated energy system is simulated by means of dynamic modeling under daily variable working conditions. Results confirm that the model is stable and able to determine the time behavior of the integrated plant. Energy saving is evaluated, and daily trends of key thermophysical parameters are reported and discussed. The analysis of thermal recovering from the flue gases shows that it is possible to recover a large energy share from the turbine exhausts. Hence, the system can generate electricity for port cold ironing and, through a secondary brine loop, cold exergy for a refrigeration plant. Overall, the proposed solution allows primary energy savings up to 22% when compared with equivalent standard technologies with the same final user needs. The exploitation of an LNG regasification process through smart integration of energy systems and implementation of efficient energy grids can contribute to greener energy management in harbors.

Ports are primary importance infrastructures when considering the transportation of people and goods across the planet. Two of the biggest issues linked to harbor areas are the pollutant emissions from moored ships, as well as the huge energy demand coming from ships and other activities that take place inside of the port boundaries. To tackle these challenges, the effort on the ship-side is to promote the transition to Liquefied Natural Gas (LNG) propulsion, while on the harbor-side is to implement electrical ship feeding. In general, using LNG for bunkering purposes implies its storage onshore using dedicated tanks. The regasification of LNG in situ can be exploited to cool down a water-brine flow (i.e. ethyl-alcohol and water). The cold brine can be used to increase the efficiency of a standard inverse cycle to produce cold (i.e. -30°C) used for refrigeration purposes inside ports. Then, the NG flow can be used to produce electrical energy with a standard turbogas cycle with energy recovery from flue gases. The generated electricity directly runs the standard inverse cycle with ethyl-alcohol and water brine to completely fulfill the energy demand for cold thermal power. The electricity still available is then used to supply the onboard systems of moored ships, or otherwise is sold to the users operating in the port. The flue gas coming from the turbogas plant can be used to provide both heating and process heat, through a dedicated heat exchanger and a natural gas boiler. The new envisaged plant can exploit all possible useful effects coming from the regasification process, helping to push towards a greener energy management system in harbor areas, through smart operative integration of the several available energy systems and the implementation of efficient energy smart grids.