Numerical Study on the Temperature Behavior in Naturally Fractured Geothermal Reservoirs and Analysis Methodology for Geothermal Reservoir Characterization and Development

An important way to develop geothermal energy is by producing low-medium temperature fluids from naturally fractured geothermal reservoirs. Pressure analysis is the most used to characterize such reservoirs for improving development efficiency. However, pressure inversion easily leads to non-uniqueness and cannot estimate thermal properties. Additionally, no reliable methods are proposed to evaluate the development potential of geothermal reservoirs. To narrow the gap, this study aims at studying the temperature behaviors and exploring suitable analysis method for characterizing geothermal reservoir and evaluating development potential. The numerical and analytical models are simultaneously established to analyze the temperature behaviors. Our models account for the J-T effect (μJT), adiabatic heat expansion/compression effect (η), reservoir damage, viscous dissipation, heat conduction and convection effects. The solution's development is dependent on the fact that the effects of reservoir temperature changes on transient pressure can be ignored so that the pressure and energy equations can be decoupled. We firstly compute reservoir pressure field based on Kazemi model, then use this obtained pressure field to solve the energy-balance equations. The numerical solution is verified and is found to be in good agreement with the proposed analytical solutions. This work shows that the most used constant μJT and η assumption will produce inaccurate temperature results when reservoir temperature changes significantly. Moreover, we find that temperature behaviors can exhibit three heat radial flow regimes (HRFR) and a heat inter-porosity regime with V-shape characteristic. Fracture thermal storativity ratio and matrix heat inter-porosity coefficient defined in this study can be estimated from this characteristic, which are further used to evaluate geothermal development potential. Our work also shows that temperature data can give information that would not be provided by conventional pressure analysis. The temperature derivative curve will show ‘hump’ characteristic if reservoir is damaged. The temperature data can characterize the skin-zone radius and permeability. More than that, the properties such as J-T coefficient, effective adiabatic heat expansion coefficient and porosity can be estimated. Eventually, an integrated workflow of using both temperature and pressure data analysis is presented to characterize naturally fractured geothermal reservoir for the first time. Simulated test examples were interpreted to demonstrate its applicability.

Design and Development of Light Weight Stirling Engine by using Compressor

From the nineteenth century, the mechanical transformation needs an incredible nuclear power creation. The pre-owned advances have a few specialized issues making hurt people and harming materials. There are numerous ways by which altering existing methods will assist with diminishing the uses. The work proposes the best approach to assemble and use the minimal expense Stirling motor for the efficient power energy application. A protected outside burning motor was the creation proposed by Robert Stirling to save human existence and materials. This motor is imagined for working with various temperatures without start inside by squander heat recuperation. It is worked by cyclic pressure and extension measure. The plan interaction includes the plan of chambers, heat expansion, dismissal, proficiency, power yield and some more. This motor is agreeable for individuals since it is very, less loud and minimized in size and alpha motor has more noteworthy proportion contrasted with different sorts. It is elective fuel hotspot for other fuel. This is efficient power energy application. This present’s development and execution trial of an alpha-type Stirling motor.

Synthesis, characterisation and thermal behaviour of Cu-based nano-multilayer

Cu/AlN–Al2O3 nano-multilayer (NML) was deposited by magnetron sputtering method on 42CrMo4 steel samples, starting with a 15 nm AlN–Al2O3 layer and followed by 200 alternating layers of 5 nm thick Cu and 5 nm thick AlN–Al2O3 layers. The microstructure and thermal behaviour of the as-deposited and heat-treated multilayer was studied. Starting from about 400 °C, extensive coarsening of Cu nanocrystallites and the migration of Cu within the multilayer were observed via solid-state diffusion. Part of the initial Cu even formed micron-sized reservoirs within the NML. Due to increased temperature and to the different heat expansion coefficients of Cu and the AlN–Al2O3, the latter cracked and Cu appeared on the top surface of the NML at around 250 °C. Below 900 °C, the transport of Cu to the top surface of the NML probably took place as a solid-state flow, leading to faceted copper micro-crystals. However, above 900 °C, the Cu micro-crystals found on the top of the NML have rounded shape, so they were probably formed by pre-melting of nano-layered Cu due to its high specific surface area in the NML. Even if the Cu crystals appear on the top surface of the NML via solid-state flow without pre-melting, the Cu crystals on the top surface of the NML can be potentially used in joining applications at and above 250 °C.

Cracking of Copper Brazed Steel Joints Due to Precipitation of MnS upon Cooling

The process of brazing of different steel grades by pure liquid copper foil was studied to reveal the critical conditions when cracks do or do not appear in the braze upon cooling without any external load. Steel grades C45 (S 0.030 wt.%, no Mn and no Cr), S103 (Mn 0.25 wt.% and S 0.020 wt.% with no Cr), CK60 (0.75 wt.% Mn, 0.07 wt.% S and 0.15 wt.% Cr) and EN 1.4034 (Cr 12 wt.%, Mn 1.0 wt.% and S 0.035 wt.%) are studied under identical conditions using copper foils of 70-microns-thick. The samples were held above the melting point of copper at 1100 °C under high vacuum for different time durations (between 180 and 3600 s) and then cooled spontaneously. The joints were found cracked during cooling after a certain critical holding time. This critical holding time for cracking was found to decrease with increasing the Mn content and the S content of steel. It is observed that cracking is due to the precipitation of a critical amount of MnS phase upon cooling. The MnS/Cu interface is the weakest interface in the joint (with adhesion ensured only by van-der-Waals bonds), which is broken/separated upon cooling due to difference in heat expansion coefficients of the sulfide and copper phases. Higher is the Mn and S content, shorter is the probable time required for crack to appear in the joint. The braze integrity diagram is constructed as function of solubility product of MnS in steel and holding time showing a stable crack-free technological region and an unstable technological region with high probability of crack formation.

The Effect of Static Blasting Materials on Coal Structure Changes and Methane Adsorption Characteristics

Methane in coal seam is always under the dynamic process of adsorption and desorption. It has been demonstrated that the static blasting technology is an effective way to extract methane from coal. Although it is of great significance to understand the role of static blasting materials on methane extraction, the change of methane during static blasting is not well understood due to limited research studies. In this paper, we took the reaction pressure and heat from the hydration of the static blasting materials as the main factors. Microstructure changes in the static blasting materials and coal were analyzed by scanning electron microscopy, gas chromatography, infrared spectroscopy, and mercury injection. Changes of methane adsorption and adsorption rate before and after the static blasting were also measured. Our results demonstrated that the static blasting materials entered the microcracks of the coal body and the porosity of the coal was increased by heat expansion, improving methane migration. During the blasting process, methane began to desorb from the coal and its adsorption content was decreased. In contrast, the adsorption of methane was increased after the reaction. However, methane adsorption rate is higher than that of raw coal, indicating that the adsorbed methane is easier to convert into free methane, which is conducive to emission. This is of great significance to methane extraction and the safety of mines.

Role of Heat Expansion with a Series of Ionic Liquids: The Case for Isochoric Thermoelectric Generators and Minimal Steric Repulsion

The role of convection in liquid thermoelectric cells may be difficult to predict because the inter- and intramolecular interactions are not currently incorporated into thermodynamic models. Here, we study the thermoelectric response of a series of five anhydrous 1-methyl-3- alkylimidazolium halide ionic liquids with varied chain length and counterion in a high-aspect-ratio, horizontal-temperature-gradient geometry, where convection is minimal. While a canonical constant-volume thermodynamic model predicts that the longer aliphatic groups exhibit larger Seebeck coefficients, we instead measure the opposite: Longer aliphatic chains correlate with lower densities and greater heat expansion, stronger intermolecular associations, stronger steric repulsion, and lower Seebeck coefficients. As evidence of the critical role of thermal expansion, we measure that the Seebeck effect is nonlinear: Values of −2.8 mV/K with a 10 K temperature difference and −1.8 mV/K with a 50 K difference are measured with ether ion. Our results indicate that steric repulsion and heat expansion are important considerations in ionic liquid design; with large temperature differences, the Seebeck coefficient correlates negatively with heat expansion. Our results suggest that Seebeck values will improve if thermal expansion is limited in a pressurized, isochoric, convection-free design.

Effect on the Mechanical Properties of Za-27/Graphite Reinforced Composites when Routed Through a Squeeze Casting Process

Zinc Aluminium Alloy with a presence of the alloy number of 27 is widely being used in the production as well as in the manufacturing of roller bearing and bushes mostly in the auto industry by replacing the bronze made bearings due to its low cost value along with the utmost best performance. And as an add-on, Zinc Aluminium Alloy 27 is a highly strengthened alloy with best metallurgical characters which is somewhat on the high side in the graph when relating it with other types of commonly utilized cast aluminium alloys. The current research work deals purely with increasing the mechanical characteristics of ZA 27 alloy and also to identify the characteristics of the similar alloy when it combines with a metal matrix composites that has been reinforced with the graphite which is purely produced by squeeze casting technique. With respect to this, the reinforced graphite and the Za 27 mixture increases the heat expansion and expands the autonomous lubrication property. The result of this research reveals about the input process parameter increase and then there will be a relevant improvement in its ductile character but with response to the rise in mass of the graphite particles, which will lead to the decrease in the mechanical property such as hardness.