Sequential coupled numerical simulations of an air/ground-source heat pump: Validation of the model and results of yearly simulations

Numerical simulations are important tools for the assessment of exploiting geothermal energy in heat pump applications. They can be used to evaluate the performance of the system, the long-term production scenarios and the sustainability of the geothermal reservoir. The present work introduces and describes a numerical model, in which a dedicated Matlab script has been realized to allow sequentially coupled simulations of a shallow geothermal reservoir and of a heat pump system. A mathematical model of a dual-source heat pump, working alternatively with the ground or the air as heat source/sink, has been developed in Matlab environment. The heat exchangers of the heat pump have been modelled considering the equations that govern the physical phenomena. The dynamic numerical simulator FEFLOW, based on the finite element method, has been used to simulate the behaviour of the geothermal reservoir, subjected to heat extraction/reinjection by a closed loop vertical heat exchangers field. This methodological approach is useful to evaluate the performance of the coupled system in the long term, and it is important for understanding the advantages and limits of the dual-source heat pump in assuring sustainability over time avoiding the depletion of geothermal resources. The models and their coupling have been calibrated and validated with experimental data from a shallow geothermal plant located in Tribano (Padova, IT). It consists of eight coaxial borehole heat exchangers 30 m deep, connected to a 16 kW dual-source heat pump prototype. The heat pump system provides heating and cooling to an office area. The coupled model has been used to compare the performance of the heat pump when working in air-mode only or in ground-mode only. This allowed the development of a switching control strategy between the two thermal sources. Yearly simulations with the switching strategy have shown that the seasonal performance factor of the dual-source heat pump during the heating mode can be 13.8 % higher compared to the one obtained with a conventional air source heat pump and 3.8 % higher with respect to a ground source heat pump

Discontinuity Analysis at Ruschita Marble Quarry Using Televiewer and Scanline Techniques

Stone blocks, such as marble, granite, and sandstone, are natural materials with excellent properties. The most important dimension stone in Romania is Ruschita marble, a natural stone known for its resistance to wear and ability to maintain its natural beauty, regardless of its colour. Regarding colour palette, Ruschita marble stands out for its excellent quality to suit even the most demanding requirements. It is available in shades such as yellowish, orange, pale pink or pink, with a compact structure and characteristic veining. Ruschita is Romania's most famous marble deposit, exploited since the end of the 19th century. The quarry exploitation is conditioned by naturally occurring fractures and discontinuities, such as faults, joints, and fissures, precluding larger blocks excavating with more significant commercial value. This paper describes two largely used techniques for discontinuity investigation, namely the televiewer and scanline methods used at the Ruschita marble quarry

A Combination of GPR Survey and Laboratory Rock Tests for Evaluating an Ornamental Stone Deposit in a Quarry Bench

Abstract The paper examines methods of assessing the critical fractures and quality of an ornamental stone deposit. Fracture status was evaluated by an in-situ Ground Penetrating Radar (GPR) test. The resulting 3D GPR model allowed exploration of the extension, shape, and orientation of the detected fractures surfaces. It also identified a rock stratum with a noticeably lower load of critical fractures compared to the other strata. Physico-mechanical properties were investigated by laboratory tests allowing classification of the deposit into quality categories, which provided a promising correlation with the GPR survey results

TOUGH2Viewer tutorial

TOUGH2Viewer is a Java program capable of displaying unstructured (Voronoi complying) grids, locally refined and structured grids (complying with the MESHMAKER iTOUGH2 format). In particular, TOUGH2Viewer allows to navigate through a 3D grid compatible with the iTOUGH2 data file format and see: (1) the thermodynamic variables and the material (namely, petrophysical properties) of each block; (2) maps of isovalues (2D) of all thermodynamic variables; (3) isosurfaces (3D) of all thermodynamic variables; (4) flows of mass and heat between blocks; (5) spatial profiles of thermodynamic variables, of a selected set of blocks, long a Cartesian directions; (6) time plot of thermodynamic variables of a selected block. All commands to manage a 3D visualization (zooming, pan, rotations) are CAD complying