The variations in isothermal bulk modulus with an increase in temperature are found to be related linearly with the change
in thermal pressure for geophysical minerals, such as MgO, CaO, Al2O3, MgAl2O4 and Mg2SiO4. Analysis of the relationship yields a value of the Anderson–Gruneisen parameter for each mineral in close agreement with
known values. An important finding of the present study is the derivation of an isobaric equation of state representing the
relationship between volume and temperature at ambient pressure. This equation for isobaric volume expansion looks like the
Birch equation for isothermal compression. The calculated values of volume expansion for the minerals at high temperatures
present close agreement with the available experimental data. The formulation developed in the present study has also been
used to predict the volumes at simultaneously elevated temperatures and pressures for CaSiO3 perovskite and NaCl minerals, in good agreement with the experimental values. 相似文献
Due to its large heat transfer area and stable thermal performance,the middle-deep coaxial borehole heat exchanger (CBHE) has become one of the emerging technologies to extract geothermal energy. In this paper,a numerical modeling on a three-dimensional unsteady heat transfer model of a CBHE was conducted by using software FEFLOW,in which the model simulation was compared with the other studies and was validated with experimental data. On this basis,a further simulation was done in respect of assessing the influencing factors of thermal extraction performance and thermal influence radius of the CBHE. The results show that the outlet temperature of the heat exchanger decreases rapidly at the initial stage,and then tended to be stable; and the thermal influence radius increases with the increase of borehole depth. The heat extraction rate of the borehole increases linearly with the geothermal gradient. Rock heat capacity has limited impact on the heat extraction rate,but has a great influence on the thermal influence radius of the CBHE. When there is groundwater flow in the reservoir,the increase of groundwater velocity will result in the rise of both outlet temperature and heat extraction rate. The heat affected zone extends along with the groundwater flow direction; and its influence radius is increasing along with flow velocity. In addition,the material of the inner pipe has a significant effect on the heat loss in the pipe,so it is recommended that the material with low thermal conductivity should be used if possible. 相似文献
Thermal diffusivity (D) was measured using laser-flash analysis from oriented single-crystal low-sanidine (K0.92Na0.08Al0.99Fe3+0.005Si2.95O8), and three glasses near KAlSi3O8. Viscosity measurements of the three supercooled liquids, in the range 106.8 to 1012.3 Pa s, confirm near-Arrhenian behavior, varying subtly with composition. For crystal and glass, D decreases with T, approaching a constant near 1,000 K: Dsat ∼ 0.65 ± 0.3 mm2 s−1 for bulk crystal and ∼0.53 ± 0.03 mm2 s−1 for the glass. A rapid decrease near 1,400 K is consistent with crossing the glass transition. Melt behavior is approximated
by D = 0.475 ± 0.01 mm2 s−1. Thermal conductivity (klat) of glass, calculated using previous heat capacity (CP) and new density data, increases with T because CP strongly increases with T. For melt, klat reaches a plateau near 1.45 W m−1 K−1, and is always below klat of the crystal. Melting of potassium feldspars impedes heat transport, providing positive thermal feedback that may promote
further melting in continental crust. 相似文献
Repeated measurements using thermal infrared remote sensing were used to characterize the change in canopy temperature over time and factors that influenced this change on ‘Conference’ pear trees (Pyrus communis L.). Three different types of sensors were used, a leaf porometer to measure leaf stomatal conductance, a thermal infrared camera to measure the canopy temperature and a meteorological sensor to measure weather variables. Stomatal conductance of water stressed pear was significantly lower than in the control group 9 days after stress began. This decrease in stomatal conductance reduced transpiration, reducing evaporative cooling that increased canopy temperature. Using thermal infrared imaging with wavelengths between 7.5 and13 μm, the first significant difference was measured 18 days after stress began. A second order derivative described the average rate of change of the difference between the stress treatment and control group. The average rate of change for stomatal conductance was 0.06 (mmol m−2 s−1) and for canopy temperature was −0.04 (°C) with respect to days. Thermal infrared remote sensing and data analysis presented in this study demonstrated that the differences in canopy temperatures between the water stress and control treatment due to stomata regulation can be validated. 相似文献