Innovation in ventilated tiled roofs : the HEROTILE European project

In ventilated roofs, the so-called Above Sheathing Ventilation (ASV) helps dissipating the excess heat in summer, thus reducing the cooling energy requirement. The ASV can be enhanced by increasing the air permeability of the tiled covering through the development of new tile shapes. This is the purpose of the Life HEROTILE European project, of which this work presents the preliminary analysis. The air permeability of a novel Marsigliese tile is analysed in comparison with the standard tile. The new design is improved with a higher sidelock and a new headlock pattern. A CFD model is then used to simulate the airflow through the tiles, solving the steady-state, incompressible fluid flow, in a 3D domain by means of the RANS-based standard k-ε model. A parametric study is conducted to analyse the variation in the air flow passing through the tile for different speeds and directions of the incident wind. The reference and new tile designs are compared in terms of air pressure drop and volumetric flow rate trough tiles. The novel shape increases the air permeability up to 100%; contrary to the standard shape, the new design allows also an increase of the air flow rate as the wind blows sideways.peer-reviewe

Testing of a dual-source heat pump coupled with flat-panel ground heat exchangers

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Enhancement of shallow ground heat exchanger with phase change material

Heat pumps perform better when coupled with ground as thermal source than with air. In literature, several studies and applications suggest and analyse the use of phase change materials (PCMs) coupled with single or double U-tube vertical borehole heat exchangers (BHEs). Usually, PCMs are mixed with the grouting material during the installation. An alternative solution to vertical BHEs is the use of horizontal ground heat exchangers (HGHEs). The present work investigates the possibility of coupling PCMs with a flat-panel HGHE installed inside a trench 2 m under the ground surface. The study analyses the case in which PCMs are adjacent to the HGHE, taking a cue from alternative coupling technologies which have PCMs added to the backfilling material of the trench where the HGHE is installed. The analysis has been conducted with COMSOL software tool. A simulation model of the system was developed to carry out a parametric analysis. The objective of the simulations is the investigation of the thermal behaviour of the HGHE patent pending coupled with PCMs under cycles of operation which represent how the heat pump could work in GSHP system. The results show the meaningful difference of using the PCM in direct contact with the HGHE

Dynamic thermal simulation of horizontal ground heat exchangers for renewable heating and ventilation of buildings

A ground heat exchanger is used to transfer thermal energy stored in soil in order to provide renewable heating, cooling and ventilation of a building. A computer program has been developed for simulation of the dynamic thermal performance of horizontally coupled earth-liquid heat exchanger for a ground source heat pump and earth-air heat exchanger for building ventilation. Neglecting the dynamic interactions between a heat exchanger and environments would significantly over predict its thermal performance and in terms of the amount of daily heat transfer the level of over-prediction could be as much as 463% for an earth-liquid heat exchanger and more than 100% for an earth-air heat exchanger. The daily heat transfer increases with soil moisture and for an earth-liquid heat exchanger the increase is between 3% and 35% with increase in moisture from 0.22 to 0.3 m3/m3 depending on the magnitude of heat transfer. Heat transfer through a plastic earth-liquid heat exchanger can be increased by 10%–12% if its thermal properties are improved to the same as surrounding soil. The increase is smaller between 2% and 4% for an earth-air heat exchanger. In addition, an earth-liquid heat exchanger is more efficient than an earth-air heat exchanger

A Management Strategy for Multi-Source Heat Pump Systems

The recent H2020 IDEAS project is oriented to the study of multi-source heat pump systems by investigating their behavior through dynamic simulations and on-field experiments in real small and large-scale prototypes respectively. One of the main aims of the project is the exploitation of available free energy sources, solar, air and ground using the heat pump technology. The key point in the investigated multi-source heat pump system is the optimal management of the renewable sources and the keeping of the ground storage available also in case of undersize of it and in case of buildings with unbalanced thermal load profile. In the last year of the project the algorithm for the control of sources and devices in the IDEAS system has been developed to maximize the use of renewable energies and at the same time to minimize the consumption of auxiliary energy. The present paper shows the details of this part of the project highlighting limits, potential and properties of the management system with a discussion of the results obtained from the on-field experiments. In the last part of the project, the implementation of weather forecast and artificial intelligence in the algorithm is planned