Time-averaged Temperature Research Articles

A numerical investigation on stack sides thermo-gas dynamic in a large amplitude standing wave thermoacoustic engine

The non-linear unsteady thermal field of a standing wave thermoacoustic engine (SWTE) was investigated using a finite volume computational code in a two-dimensional domain. The transient interaction between temperature and pressure fields and the level of non-linearity especially close to and out of stack plates are studied in 3 cases with different hot heat exchanger (HHX) temperatures of 700,500,450 K and ambient heat exchanger with constant temperature of 300 K. The results show regions with extremum temperatures far different from our understanding of the linear theory of thermoacoustic and the second law of thermodynamics. The gasdynamic field (pressure oscillations) close but out of the stack plates, approached its saturated single harmonic quasi-steady state in a short time (less than 0.3 s), but afterward the thermal field starts and keeps a non-sinusoidal temperature variation. Particle tracking through a Lagrangian analysis revealed that the difference of the thermodynamic cycles for particles that cross a particular region adjacent to the heat exchangers leads to these non-harmonic patterns. Furthermore, in case 1 with HHX temperature and drive ratio of 700 K and 18.2%, respectively, time-averaged temperature extremums with –23 K and +49 K differences (in comparison to AHX and HHX, respectively) were found in the final quasi-steady-state solution. The temperature differences become less considerable when the Drive ratio decreases. For the low temperature close to the AHX, Hybrid Eulerian-Lagrangian analysis, and temperature-entropy diagrams were used to explain this strange physics of generation of extremum temperatures. Thermo-acoustic cycles for ten gas parcels are analyzed to show that parcels in the resonator section visiting shortly the AHX (or HHX) region are responsible for this phenomenon. The thermodynamic cycle for different particles, including interactions of the gas-dynamic field with the thermal field, are analyzed with different tools to justify its strange physics. It is concluded that linear theories do not observe important phenomena in thermoacoustic engines with high-pressure amplitudes. A similar logic holds for the formation of a hot temperature region out of the HHX side of the stack.

Interaction effect of adjacent pores on plasma generation inside pores of porous catalysts

A study on the influence of pore characteristics on the microdischarge plasma inside pores of catalyst is important for understanding plasma catalysis mechanism. This article focuses on the effect of pore interaction on plasma production in pores including electron density, electron temperature, and total ion density, etc. These parameters are calculated by solving the electron energy density conservation equation, electron convection diffusion equation, heavy species conservation equation and Poisson equation. The numerical simulation results show that the distribution of electron density, electron temperature and electric field in and near a pore is apparently affected by the adjacent pore, namely, the time-averaged electron density, total ion density and ionization rate in a pore increase with the pore spacing in the range of 8–150 μm because the loss of electrons to the wall due to the adjacent pore decreases with the increasing pore spacing, but there is an opposite law for the time-averaged electron temperature and electric field in a pore; moreover, the pore spacing presents more apparent effect on the plasma generation in a smaller pore and at higher applied voltage, indicating stronger interactions between pores at these conditions. The simulation results show that the pore characteristics of porous catalysts including pore spacing and pore diameter may affect the degradation of pollutants in plasma catalysis processes. The study is important for understanding the plasma catalysis mechanisms, especially the influence mechanism of pore interaction on microdischarge in porous catalysts.

Thermal performance analysis of concentric-tube latent heat storage systems integrated with varying energy source under various charging strategies

This study presents a comprehensive assessment of the performance of a vertical concentric tube thermal storage system. The system is charged using constant and variable solar energy sources similar to real-world conditions. The initial part of the work focuses on identifying the suitable optimal phase change material for maximizing energy storage. It later evaluates the impact of using a variable energy source compared to a constant source for charging the system. A performance assessment of the system is carried out for two approximated constant energy source cases (constant time-averaged and constant peak fluid temperatures) and an actual variable energy source (unsteady fluid temperature). The findings indicate that constant time-averaged and peak charging temperatures can lead to under-prediction by up to 25.65 % and over-prediction by up to 32.72 % in the energy storage compared to the actual case considering variable charging temperature. Two charging strategies are proposed and compared with the established cascade methodology, revealing the potential for improving thermal energy storage. The dynamic charging strategy shows promising results with potential energy storage gains of up to 55.57 %. This study emphasizes the importance of considering the variable charging source and highlights effective strategies for enhancing energy storage in the thermal storage systems.

Investigations on boiling heat transfer characteristics in non-uniform heating U-Tube bundles under rolling motion

The development of the marine environment necessitates more rapid development of marine nuclear power plants, and the U-tube bundle heat exchangers, which exist in marine nuclear power plants, play a significant role in safety and economy. However, the radial non-uniform heating (NUH) brought on by the specific structure of the U-tube complicates the boiling heat transfer characteristics. Additionally, the environment of ocean rolling motion superimposed with NUH makes heat transfer more complex. The paper analyzes the time-averaged and transient heat transfer performance by contrasting the rolling UH experiments and rolling NUH experiments. The result demonstrates that the addition of NUH causes no impact on the influenced degree of rolling motion on the time-averaged temperature characteristics, which means a weakly coupled action of NUH and rolling motion. Based on the independence principle, considering the influencing factor of rolling motion and NUH, the developed correlation for calculating time-averaged heat transfer coefficient (HTC) can capture 96.67% of the experimental data within 15% of the error line, and the average absolute error is about 5.75%. For instantaneous fluctuated characteristics, the addition of NUH has a greater impact on the fluctuated range of water temperature than that of the wall temperature, and the fluctuation introduced by rolling motion is displayed based on the effect of NUH. Besides, the calculating method for determining the HTC fluctuation amplitude under uniform heating and rolling motion conditions also applies to situations in which NUH and rolling motion coexist, and the mean absolute error is around 13.80%, indicating that the coupled action of NUH and rolling motion is less obvious in forced circulation. The fluctuation amplitude of HTC depends more on the thermal parameters and rolling parameters. Finally, a novel computational logic approach was created and proposed to estimate transient HTC under conditions for NUH and rolling motion, which can anticipate the fluctuated amplitude and period of instantaneous HTC under corresponding conditions.

Numerical study of transient convective turbulent boundary layer flow along a vertical plate: analysis of kinetic energy and its dissipation rate

ABSTRACT The present article numerically investigates the turbulent buoyancy-driven (natural convection) flow along a vertical plate with a low Reynolds turbulence two-equation k-ϵ model. The deployed turbulence model is appropriate for low Reynolds number (LRN) turbulent flow adjacent to a solid boundary, and the turbulence kinetic energy (TKE) and dissipation rate of TKE are estimated using the momentum equations and are solved simultaneously with the mean flow conservation equations. Two-dimensional time-dependent viscous incompressible turbulent flow is simulated. This flow domain is governed by a highly non-linear group of partial differential equations, namely the time-averaged continuity, momentum, and energy, and also the flow property is determined through TKE, and dissipation rate of TKE equations. Since these equations are not solvable using analytical methods, an implicit second-order finite difference method is employed to solve the governing turbulent flow equations numerically. The simulated time-averaged velocity, temperature, TKE, and dissipation rate of TKE profiles along with friction factor and heat transfer rate are computed for different values of turbulent Reynolds and Prandtl numbers. Average velocity, temperature, turbulence energy, and dissipation rate under both transient and steady-state conditions are decreased with increment in . There is a decrement in average transient velocity and turbulence energy rates with increasing values, whereas the average temperature profile increases. Average steady temperature and turbulence energy profiles are also enhanced with rising values of . The majority of researchers focus on laminar flow and thus far turbulent flow has mainly been addressed through experiments only. To better elucidate the flow in this condition, the novelty of the present study is to utilize a numerical FDM procedure to probe more deeply into the turbulence characteristics in buoyancy-driven (natural convection) flow along a vertical plate with a low Reynolds turbulence two-equation k-ϵ model, as this topic is fundamental to many applications in science and engineering. Furthermore, the results of the turbulent flow simulations obtained from the current model are corroborated with existing results for the special case of laminar flow and a good correlation is achieved.

Optimizing the trench shaped film cooling design

In this numerical study an optimized trench film cooling design is determined using a Bayesian algorithm and neural network trained RANS model. Three objective functions were considered, the area-averaged film cooling efficiency, spatial standard deviation of film cooling efficiency and hot gas ingestion into the trench. Nine geometrical design parameters were varied to allow for a 3D trench shape and to find an optimal trench design based on the initial parametrization of the trench. Jet-engine like inflow boundary conditions with respect to turbulence intensity and length scales were applied. The investigated momentum ratios (I) were 1 and 8 at a main flow Reynolds number (ReD) of 2500. For each design the steady state Reynolds Averaged Navier-Stokes (RANS) equations were solved using the commercial Computational Fluid Dynamics (CFD) code Ansys Fluent V2022 R1. The turbulence model coefficients of the generalized k−ω (GEKO) model were tuned to approximate the time-averaged 3D temperature field from a predictive Large Eddy Simulation (LES) and trained by a neural network to improve the prediction capability. The tuned GEKO model shows improved agreement with experimental data of a literature case compared to the standard GEKO model. With this tuned RANS model optimized trench designs are found and validated by additional LES’s. The optimized designs include angled side walls to improve former trench designs, particularly in mitigating hot gas entrainment into the trench, which could be omitted almost entirely.

Experimental study on the combustion characteristics of square fire

In this paper, the combustion characteristics of square fire are studied experimentally, with emphasis on the changes in flame structure during the flow evolution. A series of fire tests with different fuel types, heat release rates, and fire scales are performed. The time-averaged temperature and velocity profiles and the flame length are measured and discussed. Experimental results show that as the square fire progresses downstream from the flame base, its cross-sectional shape undergoes a square-to-round transition. In this process, the self-induced axis-switching phenomenon intensifies the square fire's turbulence, manifested as more significant axial and radial temperature fluctuations than the round fire. This enhanced turbulent mixing promotes flame burning, resulting in a greater axial temperature and velocity of the square fire than the round fire. At different fire scales, the critical height at which a square fire completes the axis-switching first increases and then slows down with increasing heat release rate, which can be well correlated by the dimensionless heat release rate normalized by the side length. Experimental data verify that Quintiere and Grove's classic model can well normalize the flame lengths of square fires at different scales. A square fire's three-dimensional flow and enhanced turbulent mixing cause a higher constant representing the near-field entrainment strength than a round fire.

Influence of the adjustable EMBr on the asymmetric flow in a thin slab caster with a misaligned SEN

The thin slab casting (TSC) of steel is a type of the continuous casting (CC) with a narrow funnel-shaped mold, characterized by the rapid solidification and fast production rates. A highly turbulent flow impacts on a growing solid shell due to the constant feeding of the fresh hot melt. That strongly affects the solidification profiles and final quality of the TSC slabs. The presented work numerically investigates the solidification inside the TSC mold with the asymmetric flow pattern caused by the misalignment (tilting) of the submerged entry nozzle (SEN). These effects were considered with and without the applied electromagnetic brake (EMBr). The influence of the adjustable EMBr on the asymmetric flow and solidification profiles including turbulent and magnetohydrodynamic (MHD) effects were studied. During consistent series of simulations, the EMBr was varied between the magnetic poles and the time-averaged velocity and temperature fields were collected. The results showed that symmetric EMBr of a local type could partially improve the asymmetry. An optimal braking scenario was found for the casing speed of 5.5 m/min and maximum EMBr value of 180 mT. The solidification and MHD models including turbulence were developed using OpenFOAM®.

Numerical study of thermal mixing phenomenon using partially averaged Navier-Stokes

Thermal mixing between cold and hot streams of fluids in a T-junction may lead to high-cycle thermal fatigue in nuclear power plant piping material. Temperature fluctuations near the wall surface are the main reason for this degradation. Computational Fluid Dynamics (CFD) using space and energy-resolving turbulence modeling paradigms can predict this transient behavior. In this study Partially averaged Navier-Stokes (PANS) turbulence method is used to simulate the Vattenfall T-junction test case. Two different values for the filter control parameter fk = 0.5 and fk = 0.25 are used. Calculations results for velocity and temperature fields are compared with Large Eddy Simulations (LES) and available experimental data. For fk = 0.5, time-averaged and root mean square (RMS) temperatures show lower values than the LES and experimental data. For fk = 0.25 both time-averaged and RMS temperature results are close to the LES and experimental values. The Power Spectral Density (PSD) of the temperature signal shows peaks in the case of both PANS-0.25 and LES in the range of 3 to 4 Hz, which is in line with the experimental results. It can be concluded that the PANS method has the capability to resolve temperature and velocity fields for thermal mixing phenomenon in T-junction pipes and can be used for the assessment of high-cycle thermal fatigue.

Simulation of Pulverized Coal Combustion Process Considering Turbulence-Radiation Interaction.

In this paper, the combustion process of a 350 MW opposite pulverized coal combustion boiler is studied using a combined field test and numerical simulation. Considering the turbulence-radiation interaction (TRI) effect caused by turbulent particle pulsation during the combustion process, the TRI model is modified by introducing optical factors. The interaction between the optical thickness and the radiation pulsation of pulverized coal particles during the combustion process is studied to learn the influences of turbulent particle combustion on radiative heat transfer. According to the analysis of the TRI influence on pulverized coal combustion, the temperature of the cross section decreases with TRI. Compared with the traditional radiation model calculation, the time-average temperature of the cross section is reduced by 49.85 K, and the deviation from the experimental data is reduced by 1.54%. It is proved that the temperature distribution in the furnace considering TRI is closer to reality. In the numerical simulation of the TRI sensitivity to the optical thickness of the particles, it is found that with TRI, the increase of optical thickness will strengthen the effect of turbulent kinetic energy in the combustion area. Due to the increase in particle density, the content of the main radiation medium produced by combustion, H2O and CO2, increases and the radiation effect in the furnace is enhanced. In the fire area with dense particles, the average temperature of the cross section increases by 28 K. Hence, the change in optical thickness causes the change of TRI parameters, and the TRI effect becomes more significant with the increase of particle load.

Soot structure and flow characteristics in turbulent non-premixed methane flames stabilised on a bluff-body

The soot properties of methane in turbulent regimes are not well characterised but are highly desirable. Methane is the main constituent of natural gas that is broadly used in many industrial combustors. Investigation of turbulent methane flames under well-defined boundary conditions is therefore useful for interpreting soot formation in practical burners and can be used for further model development. This study presents a joint experimental and numerical study of a series of turbulent non-premixed bluff-body flames fuelled with pure methane for three values of the momentum flux ratio of fuel jet to co-flowing air. Soot volume fraction (SVF) and flowfield are measured simultaneously using planar laser-induced incandescence (P-LII) and 2D-polarised particle image velocimetry (P-PIV). Additionally, time-averaged temperature, mixture fraction, OH and C2H2 concentrations are estimated numerically using RANS models. The global flame structure for all three flames features a recirculation zone with a double-vortex structure, a jet-propagating zone, and a neck zone connecting the two regions. The soot distribution within the recirculation zone shows clear distinct features, which is attributed to the mean mixture fraction distribution in this zone. Increasing the momentum flux ratio shifts the location of the mean stoichiometric mixture fraction to the rich inner vortex core, leading to a distinct peak of the total integrated soot in the inner vortex of the recirculation zone that is not observed in other cases. Also, it is deduced that the soot inception starts earlier in the recirculation zone for the flame with the highest momentum flux ratio and in the jet zone for the other two flames. Much higher soot concentration and lower intermittency are found with ethylene-based flames stabilised on the same burner and with the same operating conditions. In addition, the study has generated a database of soot and flowfield results, which can be helpful for future model validations.

Coherent Anti-Stokes Raman Scattering Measurements of Time and Length Scales of Temperature Fluctuations in a Turbulent Flame.

The ability to derive temporal and spatial scales of "instantaneous" local temperature variations in a turbulent flame by means of coherent anti-Stokes Raman scattering (CARS) spectroscopy is demonstrated, for the first time to our knowledge. The measurements employed two CARS spectrometers with synchronized nanosecond pulse-repetitive lasers. The system was enabling to record, with a high temporal resolution of about 10 ns, series of single laser shot CARS spectra of N2 molecules from two spatially overlapped or displaced probe volumes as small as 0.03 × 0.03 × 2 mm3. The spectra were being recorded at a variable delay between two sequential shots, following each other in pairs at a repetition rate of 10 Hz. The series of 500 coupled measurements, at the delays in the range 1 μs-10 ms and the displacements up to 2.5 mm, have been performed in a few points of an open premixed methane-air flame of a laboratory burner with the time-averaged temperatures in the range 1200-1800 K. From the spectra, "instantaneous" temperatures, at the given delay and probe volume distance, have been derived. This allowed the auto-correlation coefficients of temperature fluctuations versus the delay and the displacement to be calculated. These dependences enabled to evaluate temperature correlation times and lengths under various mixture flow rates and equivalence ratios.

Impact of pressure drop oscillations and parallel channel instabilities on microchannel flow boiling and critical heat flux

Microchannel flow boiling heat sinks that leverage the highly efficient heat transfer mechanisms associated with phase change are a primary candidate for cooling next-generation electronics in electric vehicles. In order to design flow boiling heat sinks for such practical applications, one key obstacle is an understanding of the conditions for occurrence of dynamic two-phase flow instabilities, to which microscale flow boiling is particularly susceptible, as well as their impact on heat transfer performance. While mapping the operational regimes of these instabilities has been well-studied, with numerous stability criteria available, their impact on the heat transfer performance of heat sinks in practical applications is not understood. This work seeks to assess the impact of pressure drop oscillations and parallel channel instabilities on the surface temperature and critical heat flux in parallel microchannel heat sinks. This is achieved through measurement of time-averaged steady-state temperatures and pressures, combined with high-frequency pressure signals and high-speed flow visualization. These data are compared across three controlled flow configurations that comprise a condition of stable flow boiling, a condition where only parallel channel instabilities can occur, and a third where both pressure drop oscillations and parallel channel instabilities can occur. Experiments are performed using the dielectric refrigerant HFE-7100 in 2 cm long parallel microchannel heat sinks with square-cross-section channels (0.25, 0.5, 0.75, and 1 mm widths) at three mass fluxes (100, 400, and 1600 kg/m2s). Across this range of conditions, the time-averaged surface temperature and critical heat flux were remarkably insensitive to the occurrence of these instabilities despite the significant hydrodynamic events and transient flow patterns observed.

Gas Temperature Distribution and Fluctuation in a Lab-Scale Fire Whirl

Fire whirls cause an increase in fire damage. This study clarified the unsteady behavior of fire whirls, considering that instantaneous changes in the temperature and flame shape of fire whirls can affect the damage to the surrounding area. Numerical simulations of a lab-scale flame that simulates a fire whirl were performed to investigate the changes in gas temperature and velocity fields under various fuel inflow velocities. The flow field was obtained by solving a continuity equation and a three-dimensional Navier-Stokes equation, and the turbulence was resolved using a large eddy simulation. A chemical equilibrium partially premixed combustion model was used, and radiation effects were considered. The time-averaged gas temperature distribution along the burner central axis revealed that the gas temperature decreased monotonically from upstream to downstream. The time-averaged velocity distribution along the burner central axis showed that the velocity decreased as one moved downstream, but the decrease was uneven. The time variation of the gas temperature demonstrated that the higher the fuel inflow velocity, especially near the burner, the greater the gas temperature flutter. Furthermore, the larger the fuel inflow velocity, the larger the flame swell and wobble. The results showed that the fuel inflow velocity affected temperature fluctuation and flame undulating movement.

Thermal mixing characteristics of T-junction incident along central axis based on Large-Eddy simulations

A large eddy simulation model was used to explore the temperature mixing characteristics of a T-junction in which a branch pipe extends into the main and the branch fluid is injected along the central axis of the main pipe. The influence of the incident velocity of the branch tube on the temperature fluctuation of the fluid mixing is considered. In the main mixing region, the dimensionless time-averaged temperature（T∗¯）is positively related to the dimensionless root mean square（Trms∗）, while the connecting pipe region shows the opposite trend. With the increase of the velocity ratio, the influence of the branch pipe structure on the main flow field gradually decreases. The rebound vortex accelerates the rupture of the vortex ring, and the higher injection speed of the branch pipe leads to an increase in the vortex strength and the range of mixing area, which enhances the mixing of the fluid and makes the temperature distribution of the flow field more uniform. Finally, through the power spectral density analysis of temperature fluctuations, it is not only found that the high-energy vortex ring falls off to the near-wall region, dominating the temperature fluctuation in this region, but also this type of T-junction greatly reduces the risk of thermal fatigue failure.

Effects of mechanically-induced oscillations on soot formation and flame temperature in laminar diffusion flames of ethylene

An experimental study was performed to measure the effects of flame oscillations on soot concentration and flame temperature in co-flow laminar diffusion flames of ethylene. One novel aspect of this study is that flame oscillations were mechanically induced by moving the burner assembly in a reciprocating motion with an industrial computer-controlled linear stage. Motor speed was used to control the oscillation frequency. The peak-to-peak oscillation amplitude was defined as stroke, which was then used to calculate the Strouhal number. Oscillation frequencies of 5‒20 Hz and peak-to-peak amplitudes of 0.5‒3 mm were studied. At 1 mm peak-to-peak oscillation amplitude, flame oscillations switched from tip flickering type to tip-clipping type oscillations above 10 Hz. Time-averaged soot concentration increased from its value in the steady-state flame when the flame was perturbed by small oscillation frequencies and amplitudes but then decreased as the oscillation intensity was increased. The peak time-averaged soot volume fraction was 9.5 ppm in the steady-state flame and 4.5 ppm at a peak-to-peak oscillation amplitude and an oscillation frequency of 1 mm and 20 Hz, respectively. Similarly, the peak soot volume fraction was 5.8 ppm at a peak-to-peak oscillation amplitude and an oscillation frequency of 3 mm and 10 Hz, respectively. The time-averaged flame temperatures were in the range of 1500‒2000 K. The low-temperature zone was observed at the flame core in the steady-state flame and for low-intensity oscillations, and at the flame tip for high-intensity oscillations. The literature has discrepancies on how flame oscillations affect the total soot loading in ethylene flames. Our results show that the total soot loading increased by about 10% from steady-state to low-intensity oscillations, then slightly decreased as either oscillation frequency or amplitude was increased. The effects of increasing the oscillation frequency or amplitude were similar and well captured by the revised Strouhal number.

Self-similar characteristics of underexpanded, cryogenic hydrogen and methane jets

Underexpanded, cryogenic hydrogen and methane jets were measured using laser Raman scattering diagnostic. The jets were released from 1 mm to 1.25 mm orifices for the stagnation pressure ranges of 2–6 bar and temperature ranges of 37–46 K (hydrogen) and 112–189 K (methane). Raman signals are inherently small, thus a denoising algorithm was developed to substantially reduce the noise hindering the statistical analysis of the data. The time-averaged concentration and temperature data were plotted to show a hyperbolic decay law along the jet centerline and a Gaussian distribution in the radial direction. The concentration fluctuations of the cryogenic jets are similar to those of warm jets, the centerline RMS mass fraction decays similarly to the mean mass fraction, and the highest radial concentration fluctuations appear in the shear layer. Thus, the self-similar characteristics of the cryogenic jets are comparable with room-temperature jets for the present test conditions.

Thermoacoustic Soret separation.

In a fluid mixture in a channel with an axial time-averaged temperature gradient, high-amplitude oscillating flow can greatly increase the axial flux of thermal diffusion (Soret) separation of the components of the mixture. The enhancement occurs when the oscillating lateral temperature gradient greatly exceeds the axial gradient, causing a large oscillating concentration that can be favorably time-phased with the oscillating flow. This process can occur even with a negligible pressure oscillation or with a negligible temperature response to pressure, as is the case in most liquid solutions. The thermal boundary condition imposed by realistic solids on thermoacoustic liquids is imperfect, adding mathematical complications that are absent for typical gases, for which the solid surface is temporally isothermal. Compared with gas mixtures, the high Lewis number in typical liquid solutions reduces the separation flux associated with the time-averaged temperature gradient, but it also reduces the remixing associated with the time-averaged mole-fraction gradient. For large enough channels, the second-law separation efficiency is only slightly reduced from that of steady liquid Soret separation.

Viscous dissipation in asymmetrical thermal boundaries microchannels in extended Stokes's second problem

Two new analytical temperature solutions are reported on the viscous dissipation effect in a microchannel flow driven by an oscillating lower plate, an extension of Stokes's second problem. The methodology is solving the momentum and energy equations analytically, assuming Newtonian, one-dimensional, incompressible, laminar with constant properties. Although the velocity solution had long been obtained, only a time-averaged temperature solution had been available, until recently; when two full time-dependent temperature solutions were reported, for two symmetric temperature boundary conditions. The present work extends further with two more full solutions on asymmetric thermal conditions, namely, insulated on one oscillatory plate and isothermal on the other stationary plate, and vice-versa. Comparisons are also made with the previous two cases, and all four solutions are validated with numerical solutions. This fundamental study may have application to such a situation as the synovial flow in artificial hip-joints.

Global Warming by Geothermal Heat from Fracking: Energy Industry's Enthalpy Footprints.

Hypothetical dry adiabatic lapse rate (DALR) air expansion processes in atmosphere climate models that predict global warming cannot be the causal explanation of the experimentally observed mean lapse rate (approx.−6.5 K/km) in the troposphere. The DALR hypothesis violates the 2nd law of thermodynamics. A corollary of the heat balance revision of climate model predictions is that increasing the atmospheric concentration of a weak molecular transducer, CO2, could only have a net cooling effect, if any, on the biosphere interface temperatures between the lithosphere and atmosphere. The greenhouse-gas hypothesis, moreover, does not withstand scientific scrutiny against the experimental data. The global map of temperature difference contours is heterogeneous with various hotspots localized within specific land areas. There are regional patches of significant increases in time-average temperature differences, (∆<T>) = 3 K+, in a ring around the arctic circle, with similar hotspots in Brazil, South Africa and Madagascar, a 2–3 K band across central Australia, SE Europe centred in Poland, southern China and the Philippines. These global-warming map hotspots coincide with the locations of the most intensive fracking operational regions of the shale gas industry. Regional global warming is caused by an increase in geothermal conductivity following hydraulic fracture operations. The mean lapse rate (d<T>/dz)z at the surface of the lithosphere will decrease slightly in the regions where these operations have enhanced heat transfer. Geothermal heat from induced seismic activity has caused an irreversible increase in enthalpy (H) input into the overall energy balance at these locations. Investigating global warming further, we report the energy industry’s enthalpy outputs from the heat generated by all fuel consumption. We also calculate a global electricity usage enthalpy output. The global warming index, <∆T-biosphere> since 1950, presently +0.875 K, first became non-zero in the early 1970’s around the same time as natural gas usage began and has increased linearly by 0.0175 K/year ever since. Le Chatelier’s principle, applied to the dissipation processes of the biosphere’s ΔH-contours and [CO2] concentrations, helps to explain the global warming statistics.