Injection Heating Research Articles

A network-aware market mechanism for decentralized district heating systems

District heating systems become more distributed with the integration of prosumers, including excess heat producers and active consumers. This calls for suitable heat market mechanisms that optimally integrate these actors, while minimizing and allocating operational costs. We argue for the inclusion of network constraints to ensure network feasibility and incentivize loss reductions. We propose a network-aware heat market as a Quadratic Program (QP), which determines the optimal dispatch and a set of nodal marginal prices. While heat network dynamics are generally represented by non-convex constraints, we convexify this formulation by fixing temperature variables and neglecting pumping power. The resulting variable flow heating network model leaves the sign and size of the nodal heat injections flexible, which is important for the integration of prosumers. The market is based on peer-to-peer trades to which we add explicit loss terms. This allows us to trace network losses back to the producer and consumer of these losses. Through a dual analysis we reveal loss components of nodal prices, as well as relations between nodal prices and between seller and buyer prices. A case study illustrates the advantages of the network-aware market by comparison to our proposed loss-agnostic benchmark. We show that the network-aware market mechanism effectively promotes local heat consumption and thereby reduces losses and total cost. We conclude that the proposed loss-aware market mechanism can help reduce operating costs in district heating networks while integrating prosumers.

Fast ion transport by sawtooth instability in the presence of ICRF–NBI synergy in JET plasmas

JET experiments have shown that the three-ion scenarios using waves in the ion cyclotron range of frequencies (ICRF) is an efficient way to build fast ion population through beam ion acceleration by radio frequency (RF) waves. Such a heating scheme is applied to plasmas with at least two thermal ion species. Analysis of mixed discharges with complex heating schemes requires a workflow that allows to model thermal and fast ion transport consistently. This paper is dedicated to modelling of a mixed plasma discharge with significant fraction of fast ions and contributes to development of fast ion transport models. For interpretive analysis with the TRANSP code a JET hydrogen–deuterium plasma discharge with neutral beam injection (NBI) and ICRF heating has been chosen. The task is complicated by NBI–ICRF synergy and plasma magnetohydrodynamic activity, like sawtooth crashes. D beam ions accelerated by RF waves form a high energy tail in fast ion distribution. Significant difference between the neutron rate computed by TRANSP and measured one is observed if the same diffusivity for electrons and ions is assumed. Sensitivity studies show that uncertainties in input plasma parameters and thermal ion transport models are crucial for modelling mixed plasma discharges and increased D transport is required to reach the plasma composition consistent with diagnostic measurements at the plasma edge. Fast ion redistribution by a sawtooth instability is characterised by non-resonant transport due to reconnection of magnetic field lines and resonant transport caused by resonance interaction between the instability and fast ions. With ORBIT simulations it has been shown that resonant interaction strongly affects fast ions of high energies, like beam ions accelerated by RF waves and fusion products. For the considered case, fast ion profiles simulated by ORBIT remain peaked after the sawtooth crashes.

Novel features of the helical volumetric neutron source FFHR-b2

The compact helical fusion reactor FFHR-b2 is a multipurpose HElical Volumetric Neutron Source available as the component test facility to test the divertor and blanket systems. In the latest design, three new technologies of the high-temperature superconducting conductor, the ceramic pebble divertor, and the cartridge-type blanket are adopted. Tin-based functional liquid metals (FLMs) including lithium are considered as the working fluid for the blanket. The FLMs have multi functions of low vapor pressure, low density, low melting point, low corrosiveness, high tritium breeding ratio, and so on. The target construction cost of the FFHR-b2 has been set to 200 billion JPY. The main target of FFHR-b2 is to demonstrate the fusion gain larger than one. To achieve this in a relatively small device, the tangential neutral beam injection (NBI) heating with a moderate energy of 80 keV is adopted for the FFHR-b2. The beam-plasma fusion with 5 MW of NBI heating can produce a fusion power of 5 MW that is larger than the absorbed power of 3 MW.

First experiments on plasma production using field-aligned ICRF fast wave antennas in the large helical device

The results of the first experimental series to produce a plasma using the ion cyclotron range of frequency (ICRF) in the large helical device (LHD) within the minority scenario developed at Uragan-2M (U-2M) are presented. The motivation of this study is to provide plasma creation in conditions when an electron cyclotron resonance heating start-up is not possible, and in this way widen the operational frame of helical machines. The major constraint of the experiments is the low RF power to reduce the possibility of arcing. No dangerous voltage increase at the radio-frequency (RF) system elements and no arcing has been detected. As a result, a low plasma density is obtained and the antenna-plasma coupling is not optimal. However, such plasmas are sufficient to be used as targets for further neutral beam injection (NBI) heating. This will open possibilities to explore new regimes of operation at LHD and Wendelstein 7-X (W7-X) stellarator. The successful RF plasma production in LHD in this experimental series stimulates the planning of further studies of ICRF plasma production aimed at increasing plasma density and temperature within the ICRF minority scenario as well as investigating the plasma prolongation by NBI heating.

Effects of electron cyclotron heating on the toroidal flow in LHD plasmas

The toroidal force related to electron cyclotron heating (ECH) is investigated in large helical device (LHD) plasmas. When we apply the ECH to the plasma kept by neutral beam injection (NBI) heating, the radial profile of the toroidal flow velocity changes drastically in LHD. ECH-generated supra-thermal electrons can apply forces on the plasma through radial electron current and collisions. We investigate the perturbed electron distribution due to ECH by using the GNET code, which can solve the 5D drift kinetic equation. We also evaluate the electromagnetic force due to radial current and the collisional force driven by ECH. As a result, we find a comparable force driven by ECH to that by NBI heating. The direction of the force is the counter (co) direction radially inside (outside) from the ECH heating location, and these directions correspond with that of experiment results. Finally, we evaluate toroidal flows in ECH and NBI heated plasma solving the radial diffusion equation and compare them with that of experimental observations. We reproduce the co-rotating toroidal flow quantitatively in the balanced-NBI+ECH heated case, but we see a difference in the toroidal flow profiles in the co-NBI+ECH heated case.

Analysis of the isotropic and anisotropic Grad–Shafranov equation

Pressure anisotropy is a commonly observed phenomenon in tokamak plasmas, due to external heating methods such as neutral beam injection and ion-cyclotron resonance heating. Equilibrium models for tokamaks are constructed by solving the Grad–Shafranov equation; such models, however, do not account for pressure anisotropy since ideal magnetohydrodynamics assumes a scalar pressure. A modified Grad–Shafranov equation can be derived to include anisotropic pressure and toroidal flow by including drift-kinetic effects from the guiding-centre model of particle motion. In this work, we have studied the mathematical well-posedness of these two problems by showing the existence and uniqueness of solutions to the Grad–Shafranov equation both in the standard isotropic case and when including pressure anisotropy and toroidal flow. A new fixed-point approach is used to show the existence of solutions in the Sobolev space $H_0^1$ to the Grad–Shafranov equation, and sufficient criteria for their uniqueness are derived. The conditions required for the existence of solutions to the modified Grad–Shafranov equation are also constructed.

Gas desorption characteristics and related mechanism analysis under the action of superheated steam and pressurized water based on an experimental study

As a kind of unconventional natural gas, efficient and clean energy, CBM (Coalbed methane) exhibits great potential in adjusting energy structure and formulating energy development strategy. Desorption of methane from coal is essential for CBM production. And the desorption characteristics of methane in coal under different conditions and how to improve the desorption capacity have always been a hot issue of interest to researchers. So, research in this aspect becomes urgent. In this study, a series of desorption experiments of coal samples with various particle sizes under different adsorption pressures were carried out and the influence mechanism of pressurized water and superheated steam on the desorption was analyzed. The results were as follows: 1) The gas desorption capacity is more influenced by the adsorption pressure than the particle size, the particle size mainly affects gas release rate of the desorption process. It can be found that the lower the adsorption pressure, the more obvious the enhancement effect of superheated steam on desorption. 2) The inhibition of desorption by water injection can be attributed to four inhibition mechanisms caused by water, i.e. Water blocking effect, Wetting effect, Capillary effect, and Jamin effect. 3) Superheated steam can provide the energy required for the desorption of methane, intensify the thermal movement of molecules, and can also carry and displace methane, which together increases the desorption capacity and effective diffusion coefficient of gas in coal. These research results can provide a theoretical basis for hydraulic measures and heat injection techniques related to on-site CBM extraction.

Center Stack Casing Bakeout BUS Design for the NSTX-Upgrade Fusion Device

The National Spherical Torus eXperiment (NSTX) has undergone a major upgrade to NSTX-U at the Princeton Plasma Physics Laboratory. NSTX-U will double the toroidal field, plasma current, and neutral beam injection heating power, as well as significantly increase the pulse duration. The plasma-facing components (PFCs) in the NSTX-U vacuum vessel are mainly graphite, which has a total surface area of about 41 m2. To achieve high vacuum and reduce impurity from PFCs during operation, it is important to bake the graphite parts and remove most of the moisture absorbed by graphite during installation. Typical bakeout for NSTX-U lasts about 3 to 4 weeks. The NSTX-U inner vacuum vessel, i.e., the center stack casing, will be heated to about 450°C by passing 8 KA direct current through it during bakeout. The design of the bakeout bus directly attached to the casing flanges at vessel top and bottom are covered in detail in this paper. At the vessel top, the water-cooled bus terminal is subject to high thermal growth (about 18 mm in the vertical direction and 3 mm in the radial direction). At the vessel bottom, the bakeout bus must withstand 120 KA of halo current during disruption, as well as dislocation from thermal growth. This paper covers the design to address all these challenges. A machined CuCrZr terminal with internal water-cooling channels was used to prevent any brazing work in high stress areas. Detailed analysis will also be covered to show that the proposed design can satisfy thermal, structural, and fatigue requirements during bakeout and operation.

Evaluation of Subsurface Heat Capacity through Oscillatory Thermal Response Tests

Two methods are currently available to estimate in a relatively short time span the subsurface heat capacity: (1) laboratory analysis of rock/soil samples; (2) measure the heat diffusion with temperature sensors in an observation well. Since the first may not be representative of in-situ conditions, and the second imply economical and logistical issues, a third option might be possible by means of so-called oscillatory thermal response tests (OTRT). The aim of the study was to evaluate the effectiveness of an OTRT as a tool to infer the subsurface heat capacity without the need of an observation well. To achieve this goal, an OTRT was carried out in a borehole heat exchanger (BHE). The total duration of injection was 6 days, with oscillation period of 12 h and amplitude of 10 W m−1. The results of the proposed methodology were compared 3-D numerical simulations and to a TRT with a constant heat injection rate with temperature response monitored from a nearby observation well. Results show that the OTRT succeeded to infer the expected subsurface heat capacity, but uncertainty is about 15% and the radial depth of penetration is only 12 cm. The parameters having most impact on the results are the subsurface thermal conductivity and the borehole thermal resistance. The OTRT performed and analyzed in this study also allowed to evaluate the thermal conductivity with similar accuracy compared to conventional TRTs (3%). On the other hand, it returned borehole thermal resistance with high uncertainty (15%), in particular due to the duration of the test. The final range of heat capacity is wide, highlighting challenges to currently use OTRT in the scope of ground-coupled heat pump system design. OTRT appears a promising tool to evaluate the heat capacity, but more field testing and mathematical interpretation of the sinusoidal response is needed to better isolate the subsurface from the BHE contribution and reduce the uncertainty.

An extensive record of orogenesis recorded in a Madagascar granulite

AbstractWe present a comprehensive petrological and geochronological study of a single granulite sample from the lithosphere‐scale Beraketa shear zone in southern Madagascar to constrain the orogenic history of Gondwana assembly in this region. The studied sample provides a panoply of data constraining the prograde, retrograde, and late metasomatic history of the region via the application of Ti‐in‐quartz, Ti‐in‐zircon, Zr‐in‐rutile, and Al‐in‐orthopyroxene thermobarometry; phase‐equilibrium modelling; U–Pb monazite, zircon, and rutile petrochronology; and trace element diffusion chronometry in rutile. Our results reveal five stages of metamorphism along a narrow clockwise P–T path that may have begun as early as 620–600 Ma and certainly by 580–560 Ma, based on the oldest concordant zircon dates. The rock was heated to >725°C at less than 7.5 kbar (Stage 1) before burial to ~8 kbar (Stage 2). By c. 540 Ma, the rock had heated to ~970°C at ~9 kbar, and lost approximately 12% melt (Stage 3), before decompressing and cooling to the solidus at ~860°C and 6.5 kbar within 10 Ma (Stage 4). The vast majority of monazite and zircon dates record Stage 4 cooling and exhumation. Monazite and zircon rim dates as young as c. 510 Ma record subsolidus cooling (Stage 5) and associated symplectite formation around garnet. U–Pb rutile dates record partial resetting at c. 460 Ma; Zr‐ and Nb‐in‐rutile diffusion chronometry link these dates to a metasomatic event that lasted <1 Ma at ~600°C. In addition to chronicling a near‐complete cycle of metamorphism in southern Madagascar, this study constrains the rates of heating and cooling. We estimate that heating (7–14°C/Ma) outpaced reasonable radiogenic heating rates with modest mantle heat conduction. Therefore, we conclude that elevated mantle heat conduction or injection of mantle‐derived magmas likely contributed to regional ultrahigh‐temperature metamorphism (UHTM). Exhumation and cooling from peak metamorphic conditions to the solidus occurred at rates greater than 0.45 km/Ma and 14°C/Ma.

MP33-14 EFFICACY OF LOW INTENSITY ULTRASOUND-EXPOSED MAGNETOSOMES IN THE TREATMENT OF PROSTATE CANCER IN A XENOGRAFT MURINE MODEL

You have accessJournal of UrologyProstate Cancer: Basic Research & Pathophysiology I (MP33)1 Sep 2021MP33-14 EFFICACY OF LOW INTENSITY ULTRASOUND-EXPOSED MAGNETOSOMES IN THE TREATMENT OF PROSTATE CANCER IN A XENOGRAFT MURINE MODEL Cynthia El Hedjaj, Eric Barret, Imene Chebbi, and Edouard Alphandery Cynthia El HedjajCynthia El Hedjaj More articles by this author , Eric BarretEric Barret More articles by this author , Imene ChebbiImene Chebbi More articles by this author , and Edouard AlphanderyEdouard Alphandery More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000002042.14AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: To ablate prostate tumors by intra-tumoral injection of magnetosomes and moderate ultrasound heating in a preclinical setting. METHODS: Nanoparticles used in this study were magnetosomes extracted and purified from magnetotactic bacteria. The resulting pure endotoxin free iron oxide minerals were coated with carboxy-methyl-dextran to yield stable coated magnetosome minerals (M-CMD). Treatment efficacy was tested on 4 groups of 10 mice each, bearing PC3-Luc tumours of ∼100 mm3. In vivo experiments followed the Charles Darwin ethical guidelines. Mice received intra-tumoral injection of isotonic solution (group 1), 3 µg per mm3 of tumour of M-CMD (group 2), the same injection of magnetosome as in group 2 followed by 10 sessions of 10 min (3 sessions per week), using a power of 1 W/cm2 and a frequency of 1 MHz (group 3), isotonic solution followed by the same sessions as in group 3 (group 4). Tumour growth after treatments was monitored by measurements of tumour volumes with a calliper and of tumour bioluminescence intensity (BLI). Histological analysis was carried out using Hematoxylin & Eosin/Pearl staining on tissues located in the region of the initial tumour following the various treatments. RESULTS: In group 3 mice, each session of ultrasound application led to an average tumour temperature of 45 °C during 8 minutes. The tumour volume decreased to 0 mm3, becoming un-palpable, and tumour BLI was undetectable 15 days following M-CMD administration. No tumour re-growth was observed during the 45 following days, suggesting full disappearance of the treated primary tumour. Histological analysis of collected tissues after the hyperthermia sessions revealed magnetosome cellular internalization, tumour cell apoptosis and necrosis, and an increase in the percentage of dead tumour cells with increasing number of hyperthermia sessions. In groups 1 and 2 not exposed to ultrasounds, tumours grew rapidly and mice had to be euthanized within one month following isotonic solution/M-CMD injection. In group 4 mice that had the same ultrasound sessions as in group 3 mice without M-CMD injection, a partial anti-tumour activity was observed. The treatment could not prevent tumour re-growth as in group 3. No major side effects were noted in the 4 groups. CONCLUSIONS: Intra-tumoral magnetosomes injection heated to a moderate temperature (45°) by low intensity ultrasounds is a safe and effective treatment of prostate cancer in a murine model. This technique appears promising for clinical applications since it is efficient on mice, relies on cheap and easy to use ultrasound device without a high level of focalisation. Source of Funding: Nanobacterie- 36 boulevard Flandrin, 75016 PARIS © 2021 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 206Issue Supplement 3September 2021Page: e612-e612 Advertisement Copyright & Permissions© 2021 by American Urological Association Education and Research, Inc.MetricsAuthor Information Cynthia El Hedjaj More articles by this author Eric Barret More articles by this author Imene Chebbi More articles by this author Edouard Alphandery More articles by this author Expand All Advertisement Loading ...

Dynamic modeling of water temperature and flow in large water system

Thermal energy counts for a large part of the total energy consumption. To reduce fossil fuel consumption for heat and cold generation, different low temperature heat sources have been considered. Water networks have been considered as a large amount of water flow through it. To measure the thermal potential of the system, this paper provides a method in unsteady state to determine water temperature and flow in large water systems made of buried pipes. The model has been applied to a raw water supply system made up of 5000 km of piping and carrying 200 million m3 annually situated in the south of France. Water temperature is calculated considering heat exchange and the spatial specificities of the network (diameter of the pipes, depth, type of soil …). Soil and water temperature measurements have been made to validate the model values. The model can predict water flow and temperature according to time with good accuracy: maximal error of 10% on the flow is obtained, the root mean square error on the calculated temperature is 0.84∘C, and the correlation coefficient between the calculated and the measured temperature values is 0.98. The impact of adding several heat (or cold) injections in the system has been evaluated with the model. After a 2 MW heat exchange, the water temperature is increased by at least 1circC for 10 km downstream the exchange.

Experimental observations of local plasma parameters in the COMPASS divertor in NBI-assisted L-mode plasmas

This paper presents an experimental characterization of the local plasma parameters in the COMPASS open divertor in deuterium, L-mode plasmas by means of Langmuir probes during neutral beam injection (NBI) heating. The effect of NBI heating of the core plasma on the local divertor plasma parameters is investigated under different plasma configurations and different directions of the magnetic field and plasma current for different line-averaged electron densities. At low line-averaged densities below 6 × 1019 m-3, a low NBI heating power level does not lead to any significant changes in the plasma parameters in the divertor region. It is also found that for a reversed magnetic field the influence of NBI in the divertor is stronger at higher line-averaged electron density and plasma current. In the divertor, the impact of the NBI heating is more pronounced at high delivered powers (above P NBI = 320 kW) and line-averaged densities (above 7 × 1019 m-3). The electron temperature and the floating potential at the outer target increases respectively with 10–50% and 100%, while the plasma potential in the inner divertor increases twofold. At a higher line-averaged density, the NBI heating affects the edge plasma, namely, the electron temperature in the midplane scrape-off layer and the heating moves toward the divertor. Thus, a twice as high electron temperature is observed in the divertor and a bi-Maxwellian electron energy distribution function arises.

Neutron characterization analysis of the negative ion-based neutral beam verification facility for CFETR

Neutral beam injection heating with negative ion source is one of the important auxiliary heating system to achieve the high parameter steady- state operation goal for CFETR. A Negative ion-based Neutral Beam Verification Facility (NNBVF), a conceptual design for testing the engineering feasibility of neutral beam injection systems, is proposed for the Chinese Fusion Engineering Test Reactor (CFETR). The neutral-beam injectors used for CFETR will operate with deuterium. Inevitably, a large number of neutrons are generated between beam deuterons and deuterons implanted in the calorimeter. Neutron source is one of the important input data for radiation analysis. The neutron characterization on the calorimeter surface were explored by using a multiaperture Gaussian divergence model and the local mixing model. The total neutron intensity reach up to 1.2 × 1014 n/s for 400 keV deuteron beam. Initial results revealed that the aspect ratio of the neutron beam profile decreases with increasing beam divergence. The shape of the neutron profile on the calorimeter surface remains the same for the beam density distributions. This implies the neutron intensity emitted from the target is suitable for the beam density distribution diagnostic applications.

Catalytically stabilized combustion characteristics of methane-air mixtures in micro-scale heat-recirculating systems

In applying catalysis to real combustion systems, the modeling of chemistry and transport interactions may be the key to understanding combustion characteristics. The catalytically stabilized combustion characteristics of a methane-air mixture in a micro-scale heat-recirculating system were investigated to gain a greater understanding of the mechanisms of flame stabilization and to gain new insights into how to design the system with improved robustness and stability. The system comprised catalytically-active and catalytically-inactive channels in a counterflow heat exchange relationship. The essential factors for design considerations were determined with improved flame stability and combustion characteristics. Two primary mechanisms responsible for the loss of flame stability were discussed. The results indicated that both chemical and thermal environments are improved with the catalytically stabilized combustion method and the heat-recirculating structure. The design incorporates the best features of both catalytic combustion and thermal flame methods. The system is essentially free of mass transfer limitations. Excess enthalpy combustion can occur in an efficient and rapid manner, resulting from the injection of free radicals and heat produced by the catalytic reaction. The flow velocity, wall thermal conductivity, equivalence ratio, exterior heat losses are important factors in determining the performance of the system. Stable operation of the system is limited to a relatively wide flow regime, and the flow velocity is critical to achieving flame stability. There is an optimum wall thermal conductivity in terms of flame stability. The system with a moderate wall thermal conductivity will be most robust against the surrounding conditions. Blowout shifts homogeneous combustion downstream significantly without substantially reducing the reaction rate. Finally, engineering maps denoting flame stability were constructed, and design recommendations were made.

Productivity Analysis of Fuyu Oil Shale In-Situ Pyrolysis by Injecting Hot Nitrogen

In this paper, the effect of heat injection on productivity of Fuyu oil shale during in-situ pyrolysis was studied by using heat flow coupling analysis method. It is found that fluid conducts heat transmission to the oil shale stratum mainly along the fissure formed by hydraulic fracturing. With the increase of heating time, the oil shale on both sides of fissures were effectively pyrolyzed, and the porosity of the formation increases and the diffusion range of the nitrogen to the oil shale stratum is also improved. After 200 days, the oil shale around the fractures first reaches the pyrolysis temperature, and 700 days later, the average temperature of the oil shale stratum reaches 500 °C; therefore, the whole oil shale can be effectively pyrolyzed. Productivity analysis shows that the best exploitation temperature is 500 °C. When the gas injection rate is in the range of 1.0~11.0 m3/min, different degrees of heat loss will occur, and the output is also different. The pyrolysis time reaches 100~150 days, showing the peak value of daily production, which is between 0.5~3.2 m3/day. The pressure of displacement fluid affects oil shale product recovery in in-situ pyrolysis. High pressure helps to improve the displacement efficiency of oil and gas products and increase the productivity of oil shale in-situ pyrolysis. The best acting pressure is 9.5 MPa.

Mediterranean heat injection to the North Atlantic delayed the intensification of Northern Hemisphere glaciations

The intensification of Northern Hemisphere glaciations at the end of the Pliocene epoch marks one of the most substantial climatic shifts of the Cenozoic. Despite global cooling, sea surface temperatures in the high latitude North Atlantic Ocean rose between 2.9–2.7 million years ago. Here we present sedimentary geochemical proxy data from the Gulf of Cadiz to reconstruct the variability of Mediterranean Outflow Water, an important heat source to the North Atlantic. We find evidence for enhanced production of Mediterranean Outflow from the mid-Pliocene to the late Pliocene which we infer could have driven a sub-surface heat channel into the high-latitude North Atlantic. We then use Earth System Models to constrain the impact of enhanced Mediterranean Outflow production on the northward heat transport in the North Atlantic. In accord with the proxy data, the numerical model results support the formation of a sub-surface channel that pumped heat from the subtropics into the high latitude North Atlantic. We further suggest that this mechanism could have delayed ice sheet growth at the end of the Pliocene.

Experimental analysis of the effect of temperature on coal pore structure transformation

Coal has a complex pore network, which affects the reserves and production capacity of coalbed methane. To analyze the feasibility of coal seam heat injection mining and improve the theory of the influence of temperature on coal adsorption and desorption characteristics, scanning electron microscopy, mercury intrusion, and low-temperature liquid-nitrogen adsorption were used to evaluate the pore structure of coal at different temperatures. With the increase in temperature, the volume of macropores increased from 0.0249 to 0.0454 mL/g, and the specific surface area of micropores decreased from 2.6836 to 0.7250 m2/g. In addition, the pore fractal dimension of the large pore section, D1, increased gradually, while the pore fractal dimension of small pore section, D3, decreases with the increase in temperature. A higher temperature led to a larger pore fractal dimension of the large pores in coal and more developed pores, which is conducive to the migration of gas in the coal seam. The pore fractal dimension of the small pores decreased with the increase in temperature. The structure of the micropores became increasingly regular. The temperature has an obvious transformation effect on the structure of coal pores, especially on macropores and micropores.

Suction and injection effect on magnetohydrodynamic fluid flow within a vertical annulus for electrical wire cooling

In this article, natural convection of MHD fluid flow within a vertical annulus is investigated in existence of radial magnetic field and heat generation or absorption. As an innovation effect of suction and injection has been considered in the velocity and temperature equations. governing equations are solved by Akbari-Ganji's analytical method (AGM) and results are compared with numerical method (Runge-Kutta 4th) and LSM method (least square method) for purpose of showing the accuracy of AGM. Studies were performed for various parameters such as: suction and injection parameter (S), heat generation or absorption (H) and Hartmann number (M) under two boundary conditions isothermal and constant heat flux. Results indicate that with increasing heat generation velocity, temperature and mass flow rate in both boundary conditions are increase while opposite trend are observed for increasing heat absorption. velocity of fluid decreases when Hartmann number increase. Also, it is explained that Nusselt number increases with suction and heat absorption parameters and decreases with injection and heat generation parameters. Phenomenon and parameters studied in this work can give a good insight for cooling electronic equipment such as wire cooling.

Towards the development of cavitation technology for gas hydrate prevention.

In offshore gas well drilling and production, methane hydrate may block the tubing, resulting in the stoppage of gas production. Conventional methods such as injection of thermal hydrate inhibitors, thermal insulating or heating, gas dehydration and reducing pressure are time-consuming and expensive, and sometimes, they are not realistic in production conditions. New methods are needed to lower the cost of gas hydrate prevention and to overcome these limitations. The thermal effect of cavitation was applied to the prevention of gas hydrate in this study. The thermal impact of cavitation, supposed to heat the fluids and prevent the formation of gas hydrate, was evaluated. Numerical simulation was performed to study the thermal performance of cavitation. Furthermore, experimental studies of the influence of initial temperature, flow rate, fluid volume and fluid viscosity on the thermal effect of cavitation were performed, and the results were analysed.