LCA Analysis of Renewable Domestic Hot Water Systems with Unglazed and Glazed Solar Thermal Panels

Abstract The paper presents a from-cradle-to-grave LCA (Eco-Indicator 99, Egalitarian Approach) study for two domestic solar hot water systems (DSHWS): a traditional one with glazed panels and a system with unglazed solar collectors. Both systems are coupled with a 300-liters storage tank. The performed LCA returns an EI99 equal to 198.19 for the traditional glazed DSHWS and equal to 18.28 for the unglazed one. For each DSHWS the energy, CO 2 and economic pay-back times were calculated for three different locations (Rome, Madrid and Munich) in order to take into account the influence of local climate on the solar panels yields. The payback times took as basis of comparison two competitive technologies: the natural gas and the electrical boiler

Effects of temperature on the crystal structure of epidote: a neutron single-crystal diffraction study at 293 and 1070K

The effects of temperature on the crystal structure of a natural epidote [Ca1.925 Fe0.745Al2.265Ti0.004Si3.037O12(OH), a = 8.890(6), b = 5.630(4), c = 10. 50(6) \uc5 and \u3b2 = 115.36(5)\ub0, Sp.Gr. P21/m] have been investigated by means of neutron single-crystal diffraction at 293 and 1,070 K. At room conditions, the structural refinement confirms the presence of Fe3+ at the M3 site [%Fe(M3) = 73.1(8)%] and all attempts to refine the amount of Fe at the M(1) site were unsuccessful. Only one independent proton site was located. Two possible hydrogen bonds, with O(2) and O(4) as acceptors [i.e. O(10)-H(1)\ub7\ub7\ub7O(2) and O(10)-H(1)\ub7\ub7\ub7O(4)], occur. However, the topological configuration of the bonds suggests that the O(10)-H(1)\ub7\ub7\ub7O(4) is energetically more favourable, as H(1)\ub7\ub7\ub7O(4) = 1.9731(28) \uc5, O(10)\ub7\ub7\ub7O(4) = 2.9318(22) \uc5 and O(10)-H(1)\ub7\ub7\ub7O4 = 166.7(2)\ub0, whereas H(1)\ub7\ub7\ub7O(2) = 2.5921(23) \uc5, O(10)\ub7\ub7\ub7O(2) = 2.8221(17)\uc5 and O(10)-H(1)\ub7\ub7\ub7O2 = 93.3(1)\ub0. The O(10)-H(1) bond distance corrected for "riding motion" is 0.9943 \uc5. The diffraction data at 1,070 K show that epidote is stable within the T-range investigated, and that its crystallinity is maintained. A positive thermal expansion is observed along all the three crystallographic axes. At 1,070 K the structural refinement again shows that Fe3+ share the M(3) site along with Al3+ [%Fe(M3)1,070K = 74(2)%]. The refined amount of Fe3+ at the M(1) is not significant [%Fe(M1)1,070K = 1(2)%]. The tetrahedral and octahedral bond distances and angles show a slight distortion of the polyhedra at high-T, but a significant increase of the bond distances compared to those at room temperature is observed, especially for bond distances corrected for "rigid body motions". The high-T conditions also affect the inter-polyhedral configurations: the bridging angle Si(2)-O(9)-Si(1) of the Si2O7 group increases significantly with T. The high-T structure refinement shows that no dehydration effect occurs at least within the T-range investigated. The configuration of the H-bonding is basically maintained with temperature. However, the hydrogen bond strength changes at 1,070 K, as the O(10)\ub7\ub7\ub7O(4) and H(1)\ub7\ub7\ub7O(4) distances are slightly longer than those at 293 K. The anisotropic displacement parameters of the proton site are significantly larger than those at room condition. Reasons for the thermal stability of epidote up to 1,070 K observed in this study, the absence of dehydration and/or non-convergent ordering of Al and Fe3+ between different octahedral sites and/or convergent ordering on M(3) are discussed

Thermal behavior of davyne-group minerals

The thermal behaviour of microsommite (MC), davyne from Vesuvius (DV) and from Zabargad (DZ) was determined by X-ray single crystal data obtained employing a microfurnace connected to a four-circle diffractometer. Upon heating, the a parameter increased linearly, with similar thermal expansion rates for the three samples: the mean linear expansion coefficients, alpha(a), were 10.2(3). 10(-6), 13.4(7). 10(-6), 15.1(8). 10(-6) K-1 for MC, DV and DZ respectively. At about 473 K both MC and DZ showed a discontinuity in the expansion of the c parameter. The mean linear expansion coefficient, alpha(c), changed abruptly from 16(4). 10(-6) K-1 for both minerals below the discontinuity to 2(1). 10(-6) and 3(1). 10(-6) K-1 for MC and DZ, respectively, above the discontinuity. In DV, however, the alpha(c) coefficient was constant between 293 und 827 K and equal to 1(2). 10(-6) K-1. The substructure of MC was refined under room conditions (R=0.055 with 758 independent reflections) in space group P6(3) and at 943 K in space group P6(3) (R=0.062, with 750 independent reflections) and in space group P6(3)/m (R=0.065 with 394 independent reflections). By comparing the structural refinements the discontinuity could be related to the tilting of the tetrahedra connected along c: for T473 K was due to the small tetrahedral expansion. In DV, where the completely stretched structure was already realized under room conditions, no phase transition occured

New insights on high-pressure behaviour of microporous materials from X-ray single-crystal data

The main deformation mechanisms induced by pressure on different structural types of zeolites were analysed by comparing experimental data and theoretical models. Data of single-crystal X-ray diffraction obtained with the sample in a Merrill-Bassett diamond anvil cell on a four-circle diffractometer were collected at different pressures for samples of heulandite, scolecite and bikitaite, using non-penetrating pressure transmitting media (glycerol or silicon oil), up to 5 GPa. The results indicated that, at first approximation, the theoretical approach reproduces the structural evolution of zeolites under pressure. However, the flexibility possessed by framework microporous silicates resulted more complex than that which can be modelled by undeformable "rigid-unit modes", being completely flexible in the oxygen hinges. Moreover, the compressibility of the zeolites under study does not appear to be directly related to the microporosity represented by the framework density (FD): The bulk moduli (simply defined as the inverse of volume compressibility coefficients) of heulandite (27.5(2) GPa) and scolecite (54.6(3) GPa) were different even though their FD's were quite similar. Single crystal data have shown that the structural evolution of the open-framework silicates, is strongly controlled by the framework, whereas the role of the extra-framework content was less important. In all three zeolites the position of the extra-framework water molecules and cations was maintained approximately and their coordination numbers remained unchanged within the pressure range investigated

High-pressure structural behaviour of scolecite

The HP structural evolution of a natural scolecite from Iceland (space group Cc) was studied up to 5 GPa using in situ single-crystal X-ray diffraction data from a diamond-anvil cell (DAC) with silicon oil as non penetrating pressure transmitting medium. Linear regressions yielded mean axial compressibilities for a, b and c axes of \u3b2a = 4.4(2).10-3, \u3b2b = 6.1(2).10-3, \u3b2c = 6.0(1).10-3 GPa-1. K0, refined with a second-order Birch-Murnagham equation, fixing K0 at 4, is 54.6(7) GPa. The bulk scolecite structure compression was the result of the "soft" behaviour of the channels (K 45 17 GPa for [100]-channels; K 45 50 GPa for [001]-channels) and the more rigid behaviour of the tetrahedral framework (K 45 96 GPa), which underwent kinking of the Secondary Building Unit (SBU) along [100]-chains. The angle between the SBUs (\u3c6), increased from 20.80(2)\ub0 at 0.0001 GPa, to 22.00(6)\ub0 at 3.38 GPa. Within the investigated pressure range, the position of the extra-framework cations and water molecules remained almost unchanged. Up to 4.2 GPa no phase transition was observed

Effects of pressure on the structure of bikitaite

The structural behaviour of bikitaite, Li2(Al2Si4O12). 2H2O, was investigated under hydrostatic pressure using X-ray single-crystal diffraction data. A Merrill-Bassett diamond anvil cell was mounted with glycerol, as non penetrating pressure-transmitting medium, ruby chips and a small crystal of quartz as the calibrant. A strong anisotropic compression was observed by linear regressions of lattice parameters against P, bikitaite being softer along the c axis (\u3b2c=9.3(1) 10-3 GPa-1), than along b (\u3b2b = 6.6(1) 10-3 GPa-1) and a (\u3b2a = 2.4(1) 10-3 GPa-1) (\u3b2a: \u3b2b: \u3b2c=1: 2.75 :3.9 . Fitting the cell-volume - pressure data to a second order Birch-Murnaghan equation of state, as indicated by the finite strain-stress plot, yielded K0 = 44.2(4) GPa, with K' = 4 and V0 = 295.58(2) \uc53. The evolution of the bikitaite structure with P was studied by comparing the results of refinements with data collected at room conditions, at 3.2 GPa and after decompression. The structure can be described as sheets of six-membered rings parallel to (001), connected by pyroxene-like chains. 8-ring and 5-ring channels run along [010] and inside the 8-ring channel there is a onedimensional chain of water molecules, which is linked to the framework through the extra-framework Li atoms. Under pressure, the kinking of the pyroxene-like chain decreased the free diameters of the 5-ring channels, strongly reducing the distance between the ab planes. On the contrary, the tridymite-like planes with 6-membered rings were more rigid. The positions of the extra-framework cations and water were maintained at HP even though the configuration of the water chains changed slightly: the distances between the water molecules decreased, whereas the kinking angle of the chain increased