Hot Fluid Research Articles

Numerical investigation on energetic and exergetic performance of triplex concentric tube heat exchanger using MXene nanofluids

This study examines the heat transfer and fluid flow parameters for pure water and water-based (0.1–2% v/v.) MXene and (1% v/v.) Al2O3 nanofluid as hot fluids in a triplex tube heat exchanger (TTHX). Using a counter-flow configuration of the TTHX system, the research investigated the effects of the Reynolds number and volume fraction of nanoparticles on effectiveness, hydrothermal exergy loss, and entropy generation analysis. In the TTHX intermediate tube, the mass flow rate ranged from 0.06 kg/s to 1.6 kg/s, and a temperature of 343 K was considered. The key findings indicate that the 1% v/v. MXene nanofluid enhances the heat transfer rate by 12.5% compared to the Al2O3 nanofluid and by 20% compared to pure water in the TTHX system. The MXene nanofluid had 14.28% higher friction factor than pure water and 3.26% higher than the Al2O3 nanofluid. Increase in Nusselt number as compared to pure water is found to be 5.53%, 7.36%, 10%, 12.65%, 15% and 16.36% for Al2O3 nf, 0.1% Mxene nf, 0.5% Mxene nf, 1% Mxene nf, 1.5% Mxene nf and 2% Mxene nf respectively, at Reynolds number of 6800. The performance evaluation criteria for MXene nanofluid are 21.73% higher than for Al2O3 nanofluid at a Re of 6800, with an internal annulus fluid velocity of 0.1 m/s, and a specific value of Re at 4400, 1% v/v. MXene nanofluid is 29.7% more effective than Al2O3 nanofluid. Therefore, compared to traditional fluids, MXene nanofluids can improve the performance of a TTHX system.

Harvesting Rejected Heat by the Split A/C Condenser for Producing Warm Water

This study investigates the potential use of rejected heat by outdoor A/C units. Rather from being lost to the environment, the heat will be utilized to make warm water. An experimental setup was designed and constructed that cooled down the refrigerant heat of a condenser by tap water. R22 and tap water were used as hot and cold fluid, respectively. The inlet and outlet temperature of the shell side fluid i.e., water was measured by thermocouple. The mass flow rate of the inlet water was controlled by a valve and measured using a rotameter. The influence of inlet water temperature was also investigated in this study. It is found that recovered thermal energy decreased from 3.72 kW to 2.84 kW as mass flow rate of water decreased from 0.1 kg/s to 0.07 kg/s. When water flow rate decreased to 0.05 kg/s, thermal energy of 4.28 kW was recovered due to the rapid increase of water outlet temperature. Furthermore, this heat exchanger is utilized to determine the heat released by the condenser and the temperature of the condenser-generated hot water. IUBAT Review—A Multidisciplinary Academic Journal, 7(2): 44-63

Experimental Investigation of the Effect of Different Parameters on Plate and Frame Heat Exchanger Effectiveness

Plate & frame heat exchangers use a series of metal plates to conduct heat transfer between fluids. These fluids are directed through specific channels, ensuring they remain isolated while allowing efficient heat exchange. In recent years, researchers have looked at how different characteristics affect heat exchanger performance. The purpose of this study is to examine the impact of various factors on the effectiveness of the heat exchanger. The experimental analysis was conducted using pure water, considering different Re numbers ranging from 6000 to 30000 and varying hot fluid inlet temperatures between 25℃ and 35℃. It was observed that under turbulent flow conditions, the heat transfer effectiveness increased of 13.6% when the Reynolds number varied between Re = 6000 – 20000 at constant Th,in=35℃. However, the extent of this increase diminished significantly within the Re = 20000-30000 range. When the inlet temperature of hot fluid was raised Th,in=25℃ to 35℃ the plate & frame heat exchanger effectiveness increased of 4.3%. This study provides a basis for future studies on heat exchangers used in industrial applications with different geometries and different fluids. It is considered that the results of this study could be used in the future to design more modular and efficient plate heat exchangers for industrial applications.

Numerical Modeling of a Primary Heat Exchanger in sCO2 Power Cycles for Thermal Energy Storage Systems

Abstract Renewable energy sources are the key for long-term decarbonization of energy. However, the intermittent nature of renewables does not always meet the energy demand in the electrical grid. Thus, electrical heated thermal energy storage systems (TES) coupled with sCO2 power cycles are investigated at Helmholtz-Zentrum Dresden-Rossendorf as a possible solution to balance this mismatch. In this study, a printed circuit heat exchanger (PCHE) is considered as candidate for the 1 MW primary heat exchanger, given the mechanical challenge induced by drastic pressure difference between the hot fluid of the TES and the cold fluid of the power cycle. The present work consists of two parts, one elaborates a one-dimensional (1D) model in order to optimize the PCHE regarding the pump power required to compensate the pressure loss. It was found that the hot fluid coming from the TES accounts for 80% of the total pump power after optimization because of its low density and its high mass flow rate. Furthermore, three-dimensional simulations by computational fluid dynamics (CFD) were done and compared to the results from the 1D model to ensure its validity. It was observed that the results from the 1D model and the CFD simulations are consistent, with a slight potential deviation in the calculation of the pressure profile.

Numerical Study of the Thermal Energy Storage Container Shape Impact on the NePCM Melting Process

Recently, thermal energy storage has emerged as one of the alternative solutions to increase energy efficiency. The geometry of a thermal energy storage container holds a significant role in increasing the heat transmission rates in the container. In this article, we examined the influence of the inner and outer tube shapes of a shell and tube LHTES on the thermal activity within the system. The gap between the inner and outer tube is loaded with nano-enhanced phase change material (NePCM); hot fluid is passed through the inner tube while the outer tube is insulated. COMSOL commercial software was used to numerically simulate the NePCM melting process. Mainly, six different geometries were investigated with inner or outer tubes with trefoil, cinquefoil, and heptafoil shapes. The influences of nanoparticles volumetric fraction (ϕ = 0–8%) were also discussed. The findings are displayed and discussed in terms of the average Nusselt number, the average liquid fraction, the total energy generation, and the average temperature. The findings showed that the melting process is highly affected by the shape of the inner tube and ϕ, while the outer tube shape impact is less important. It was noticed that employing an inner tube with a trefoil improved the melting process by more than 25% while increasing the ϕ from 0 to 8% resulted in reducing the melting time by up to 20%.

Computational study of the thermophysical properties of graphene oxide/vacuum residue nanofluids for enhanced oil recovery

AbstractPrior research suggests that the use of nanotechnology may greatly improve the efficiency of enhanced oil recovery methods, especially hot fluid injection. The thermophysical characteristics of the nanofluid may have an enormous effect on how well the injection process works. However, it takes both time and resources to conduct laboratory analyses of the effects of thermophysical characteristics on the effectiveness of nanofluid-based improved oil recovery methods. Computational models can effectively forecast the thermophysical characteristics of nanofluids and how they affect oil recovery efficiency, which helps overcome this difficulty. The current study investigates the flow of vacuum residue (VR) fluid, which generates entropy when suspended graphene oxide (GO) nanoparticles. When mixed convection and variable thermal conductivity are present, a static/moving wedge allows the nanofluid to propagate. The continuity, energy, entropy, and momentum equations form the foundation of the governing model. We use certain similarity variables to simplify the suggested mathematical formulations into forms for nonlinear differential equations (DEs). We show the results of the reduced equations using the Chebyshev collocation method. We present the graphical and numerical results for all the emerging parameters. For enhanced oil recovery applications, the current results are beneficial.

Dimensionless performance mapping of cryogenic plate-fin heat exchangers with ortho-para hydrogen continuous conversion for hydrogen liquefaction

Continuous conversion heat exchangers are recognized as the next-generation technology for large-scale and energy-efficient hydrogen liquefaction plants. However, their structural design and operational optimization are impeded by the absence of generalised evaluation methodology, as well as unclear coupling mechanisms of convection and conversion. This study develops a novel dimensionless model incorporating the number of heat transfer units and the Damköhler number, to describe the convective transport and catalytic conversion process for continuous conversion heat exchangers. Their comprehensive performance is evaluated by defining the cooling, conversion, and total effectiveness, based on which performance maps are subsequently proposed for three typical temperature zones. The scaling results demonstrate that the conversion-convection characteristics along the heat exchanger train exhibit multiple complex stages, heavily contingent upon the space velocity and the ratio of heat capacity rates between hot and cold fluids. To achieve the effectiveness of over 0.90, these two operational parameters should be below about 1000 h−1 and 0.50, respectively. The characteristic variables are recommended to meet Da0 ≥ 8 and NTU0 ≥ 16 as a minimum requirement for various heat exchangers. These findings offer a theoretical foundation for high-efficient design and operation of continuous conversion heat exchangers in future hydrogen liquefaction plants.

Thermophilic Behavior of Heat-Dissociative Coacervate Droplets.

In exploring the genesis of life, liquid-liquid phase-separated coacervate droplets have been proposed as primitive protocells. Within the hydrothermal hypothesis, these droplets would emerge from molecule-rich hot fluids and thus be subjected to temperature gradients. Investigating their thermophoretic behavior can provide insights into protocell footprints in thermal landscapes, advancing our understanding of life's origins. Here, we report the thermophilic behavior of heat-dissociative droplets, contrary to the intuition that heat-associative condensates would prefer hotter areas. This aspect implies the preferential presence of heat-dissociative primordial condensates near hydrothermal environments, facilitating molecular incorporation and biochemical syntheses. Additionally, our investigations reveal similarities between thermophoretic and electrophoretic motions, dictated by molecular redistribution within droplets due to their fluid nature, which necessitates revising current electrophoresis frameworks for surface charge characterization. Our study elucidates how coacervate droplets navigate thermal and electric fields, reveals their thermal-landscape-dependent molecular characteristics, and bridges foundational theories of early life: the hydrothermal and condensate-as-protocell hypotheses.

The Paleoproterozoic Raimunda Porphyry-Type Gold Deposit, Juruena Mineral Province, Amazonian Craton (Brazil): Constraints Based on Petrological, Fluid Inclusion and Stable Isotope Data

The Juruena Mineral Province is an emerging world-class mineral province in the southern Amazonian Craton, due to numerous Au-Cu and base metal deposits, such as the Raimunda deposit, related to Novo Mundo 2.03–1.98 Ga I-type calc-alkaline granites. Its hydrothermal alteration zones comprise Na-metasomatism, microclinization, propylitic and sericitic alteration, silicification, a sulfide stage, and late carbonate alteration. The disseminated mineralization, associated with the sulfide stage, the main mineralization stage, is represented by gold inclusions and fracture-filling grains in pyrite, chalcopyrite, and Cu-Bi sulfides. Chlorite geothermometer and fluid inclusion data indicate temperature conditions of 325–380 °C for the mineralization. The coexistence of high-temperature aqueous and aqueous-carbonic fluid inclusions, based on a microthermometric study of fluid inclusions, reveals a mixing of medium-saline hot fluids with cooler and low-saline fluid. The δ18Ofluid (3.11–7.86‰) and δ34Spy data (−1.4–0.1‰) are coherent to the magmatic origin of the mineralizing fluid. Gold was initially transported as chlorine complexes in a hot, high-salinity, acidic, and oxidized fluid from the magma chamber, and later as H2S− complexes. The chemical-physical instability during fluid ascent is interpreted as a triggering factor for ore precipitation. The results offer valuable insights into the genesis of porphyry–Au deposits and their implications for prospecting in the Amazonian Craton.

Thermal Hydraulic Performance and Characteristics of a Microchannel Heat Exchanger: Experimental and Numerical Investigations

Abstract This paper presents extensive fluid flow and Heat Transfer studies conducted through an experimental setup followed by a detailed three-dimensional (3D) numerical analysis of the same setup using a commercial package for computational fluid dynamics (CFD), known as cfd-ace® for additive-manufactured counterflow AlSi10 Mg microchannel heat exchangers (MCHEs). A detailed 3D computational model of the experimentally tested MCHEs was built and analyzed using the commercial software cfd-ace® for the same experimentally tested operating conditions. The computational model results are in good agreement with experimental data of tested MCHE within +2% to +7% and ∼0% to −13.5% variation for cold and hot fluids for the entire set of design of experiments (DoEs). This percentage disagreement may be due to various factors, such as manufacturing deviation within tolerance, longitudinal conduction, variation in the thermal conductivity of the material after heat treatment, variation in environmental temperature, sensor deviation, and surface roughness of internal channels. Instead of Stainless steel (SST), AlSi10 Mg was used because of its lower manufacturing cost because AlSi10 Mg was lighter than SST, though its thermal conductivity is almost ∼8–10 times more than that of SST. A higher thermal conductivity is not good for MCHEs because it leads to higher longitudinal conduction, which eventually degrades the performance of MCHEs in terms of effectiveness. MCHE effectiveness is also reduced by ∼12% to 18% owing to longitudinal conduction from ideal effectiveness.

Optimized AI-MPM: Application of PSO for tuning the hyperparameters of SVM and RF algorithms

Modern computational techniques, particularly Support Vector Machines (SVM) and Random Forest (RF) models, are revolutionizing predictive mineral prospectivity mapping. These advanced systems excel at identifying prime resource locations but require meticulous fine-tuning of their internal settings to achieve peak performance. Careful calibration of these configurations during the learning phase significantly enhances their ability to detect promising deposits. The main goal of this study is to introduce a hybrid model called PSO -SVM and PSO-RF, which aim to combine particle swarm optimization (PSO) with SVM (with RBF kernel) and RF models. This hybrid model automatically adjusts the optimized hyperparameters of SVM and RF, resulting in highly accurate predictions and a wide range of applicability. The PSO algorithm has been applied to fine-tune two main parameters (C and λ) for SVM-RBF and three main parameters (NT, NS, and d) for RF, creating efficient models for both. The proposed hybrid model as well as the traditional versions of SVM and RF models, were tested using a geo-spatial dataset related to Cu mineralization in Kerman belt, SE Iran. Forecasting algorithms were developed by integrating diverse datasets: multi-element concentrations from stream samples, bedrock and fault line maps, indicators of hot fluid interaction, aeromagnetic survey results, coordinates of previously identified copper-rich igneous intrusions, and verified ore body positions as reference points. The models' performance was evaluated using four validation methods: Multi-round data partitioning (K-fold), error classification tables (confusion matrix), true-positive vs. false-positive graphical analysis ((ROC) curve), and P-A plot were used to assess algorithms and models performance. Tests revealed that the PSO-SVM surpassed all competitors. Impressively, this fine-tuned classifier identified prime target zones in merely one-seventh of the region (14%), yet these areas encompassed nearly all verified resource sites (97%).

Enhancement of heat transfer using elliptical twisted inner pipe with convergent conical ring turbulator for turbulent flow in double pipe heat exchanger

This study focuses on evaluating the impact of a fully twisted inner pipe along with conical rings turbulator by conducting a numerical analysis of the double-pipe heat exchanger (DPHE), considering both parallel and counterflow configurations for heat transfer. As modification, a straight elliptical pipe compared with two other pipes with three twists and full twists along their lengths is also investigated to compute the heat transfer rate, pressure drop, and turbulence characteristics. Modelling has been performed using ANSYS Fluent, considering the RNG k-ε turbulence model. The regime of turbulent flow is studied within the range of Reynolds numbers from 5,000 to 26,000. Validation has been conducted comparing with the experimental studies, and reasonable agreement has been observed. The full twists effect generates a swirling motion, and conical rings are inserted inside the outer pipe as a passive turbulator to guide the flow towards the inner pipe, where the hot fluid passes. Comparing the results, the inner twisted pipe with the conical ring exhibits a significant improvement in the Nusselt number (Nu), reaching 445 in the counterflow direction with the six rings. The evaluation of entropy generation is described as a function of frictional and thermal contributions. According to the findings, turbulators slightly increase entropy development. Analysis of total entropy generation shows that, because of the high viscosity, frictional entropy generation is dominant. Also, when the vortex flow becomes stronger, the total entropy creation rate decreases down. The Performance Evaluation Criteria (PEC) is also greater than 1 for both parallel and counterflow flow, indicating that enhancement of the rate of heat transfer, outweighs the decrease in pressure drop. Particularly in counterflow directions the PEC is 2.3 which is impressive. Overall, full twists along the pipe lengths enhance the heat exchanger's performance, and full twists with six conical rings fortify most in both flow directions.

Experimental investigation on combined flow and temperature non-uniformity for three-fluid compact heat exchanger with cross flow configuration

ABSTRACT Non-uniformities in flow and temperature are the most conspicuous reason behind diminishing efficacy in heat exchangers. Cross-flow three-fluid heat exchanger being a pivotal component in cryogenics, is experimentally investigated under imposed flow and temperature non-uniformities in central hot fluid. The interaction of combined flow and temperature non-uniformity invariably precipitates a degradation in the efficacy of both adjacent fluids. About 7.3% and 6.2% of efficacy degradation is encountered in fluid “a” (for C 2 configuration) and fluid “c” (for C 1 configuration), respectively, for F N 1 + T N III model. In many cases, C 1 configuration and T N III model is inimical to fluid “c” performance.

3-D shallow crustal structure and offshore geothermal potential of the Aegean region of Türkiye from ambient noise tomography

The definition of the upper crustal structure is a necessary input in seismic hazard studies or in geothermal exploration projects. In this study, we use ambient noise tomography (ANT) to illuminate the 3-D crustal structure of the Aegean Region of Türkiye. The results allow us to identify tectonic control on seismic velocities and to image the shear-wave velocity (Vs) structure. In addition, our results characterize offshore-onshore geothermal potential in this region. Our data consists of 3-months of continuous ambient noise data recorded by 43 seismometers. The cross-correlation of seismic noise between station pairs was used to estimate Rayleigh wave pulses from which group velocity dispersion curves were derived. The results were used to estimate a group velocity dispersion curve for each cell in a square grid using tomography. Local dispersion curves were inverted to estimate a 1-D Vs profile for each cell. Integration of the results for all cells allowed us to build a 3-D Vs model of the studied region. Our Vs model is reliable for the upper 18 km of the crust. The Vs variations show narrow anticlines and basin-type wide synclines and sedimentary layers that correspond to the shallow crustal structure. An arc-shaped low velocity zone is identified to the west of the study area and is interpreted as a promising offshore geothermal zone. The southern coastal region of the investigated area also presents high hot fluid content in cracks and therefore has significant offshore geothermal potential. Our interpretation is in good agreement with available geophysical results and with the shallow crustal geometry reported in previous studies.

Physical and mechanical depth relationships of rocks from the Rotokawa Geothermal Reservoir, Taupō Volcanic Zone, New Zealand

ABSTRACT The Rotokawa geothermal field is in the Taupō Volcanic Zone, New Zealand. It hosts two geothermal power plants, Rotokawa and Ngā Awa Pūrua, which together have a capacity over 170 MWe. The permeability of the rock mass comprising a geothermal field controls the volume of hot fluids that can be extracted for energy production. In this research we produce a stress model to estimate in-situ rock matrix permeability for a unique set of intact rock samples obtained from depths up to 2600 m in the Rotokawa geothermal field. We show that permeability generally decreases with sample depth, both intrinsically and in response to increasing confining pressure. We explore this confining pressure effect on other petrophysical and mechanical measurements, and highlight how rock texture and composition affect how the rocks respond to confining pressure. For example, we compare two altered andesite samples: a breccia with microfractures and infilled pores that tends to experience less compaction and porosity decrease than a lava with rounded, unfilled pores. We suggest that, when developing depth-models, measurements should be conducted at relevant in-situ conditions, if possible. Finally, we explore relationships between different physical parameters and provide estimating functions for those with the clearest correlations.

Thermodynamic properties of non-azeotropic refrigerant heat pumps under full operating conditions with non-phase-change heat sinks and heat soucres

ABSTRACT When using pure refrigerants in heat pump, a significant temperature mismatch arises between hot and cold fluids within the evaporator and condenser, adversely impacting the thermal efficiency of system. To mitigate this issue, we incorporated non-azeotropic refrigerant blends such as R1233zd(e)/R152a, 1224 yd(z)/R152a and 1234ze(z)/R152a into heat pumps devoid of phase-change heat sinks and sources. Through rigorous examination of the temperature glide characteristics of these refrigerants, we determined an optimal R152a composition of 0.3, resulting in COPs of 3.326, 3.36, and 3.605 for the respective heat pumps. Our analysis further delved into heat pump configurations, revealing that the COP of the regenerative configuration could be substantially elevated from 3.36 (in the simple configuration) to 3.79. Additionally, the maximum temperature observed in the two-stage compression configuration was significantly lower compared to the regenerative setup. A comprehensive thermodynamic assessment = across all operating conditions indicated that COP of all configurations decreases markedly as heat production diminishes below 50% of full load. Conversely, when heat production exceeds 50% of full load, the COP remains relatively stable across different heat production levels. Notably, the COP of the regenerative configuration closely approximates that of the two-stage configuration. Considering factors such as investment cost, system complexity and operational efficiency, the regenerative configuration stands out as the optimal choice across all operating conditions.

Numerical investigation on aerothermal performances of film cooled high pressure turbine vane under inlet non-uniformities

Lean-premixed combustion technologies have been widely adopted in advanced civil turbofan engine to reduce NOx emission. There exist hot streak (HS) and swirl simultaneously at the exit of lean-premixed combustor. Current paper presents a numerical investigation on the aerothermal performances of film cooled high pressure turbine (HPT) nozzle guide vane (NGV) subjected to HS and swirl. Current investigation was carried on the stage one film cooled NGV of GE-E3 HPT, which took into consideration the realistic clocking position of HPT NGV relative to the fuel injector in combustor. The effects of swirl orientations on the migration of HS and film coolant and the aerothermal performances on NGV surface were examined. Results demonstrates that, swirl and its induced incidence angle effect turn over some film coolant from pressure side (PS) to suction side (SS), or vice versa. Such effects also dominate the radial migration of film coolant. The redistributions of film coolant show significant effect on the film cooling effectiveness on NGV surface. Compared with no-swirl case, the greater film cooling effectiveness appears at the region where film coolant accumulates, and as expected, the smaller film cooling effectiveness arises at the region covered by less film coolant. As for heat transfer coefficient (HTC), swirl affects HTC on NGV surface mainly through redistributing film coolant and the hot fluid from HS. The migrations of film coolant and hot fluid keep step with each other on the NGV surfaces directly impinged by inlet HS and swirl, so that the HTC distributions on these surfaces are not significantly affected by swirl. The radial momentum of film coolant endowed by the film hole with radial incidence angle can partly offset the swirl's induced incidence angle effect, which reduces the variations in film cooling effectiveness and heat transfer coefficient due to swirl.

Numerical investigation on the heat transfer and pressure loss characteristics of precooler under negative pressure

Precoolers have garnered considerable attention owing to their applications in aerospace and industrial fields. Nonetheless, there is a paucity of research concerning the performance of precoolers under conditions of extremely low pressure. This study conducts a numerical analysis of the heat transfer and pressure loss characteristics of a plate-fin precooler operating under negative pressure, considering the coupled heat transfer interactions among the hot fluid, solid wall, and cooling fluid. The comprehensive performance and flow field on each side of the precooler are investigated. Moreover, the impact of negative pressure on the heat transfer and pressure recovery performance of the hot fluid in the rectangle channel is evaluated. The results show that, even under operating conditions with pressures below 30 kPa and inlet temperatures exceeding 1100 K, the precooler attains a pressure recovery coefficient greater than 95.6 % and achieves a temperature drop exceeding 43.2 % for the hot fluid as the mass flow rate ranges from 0.205 kg/s to 0.564 kg/s. Additionally, the heat transfer coefficient of the hot fluid is less than 1/40 that of the cooling fluid, resulting in increased thermal resistance between the hot fluid and the wall. Consequently, a distinct thermal boundary layer develops between the hot fluid and the wall, which is not present between the cooling fluid and the wall. Furthermore, the performance of heat transfer and pressure recovery for the hot fluid exhibits considerable variability with changes in static pressure at a constant inlet velocity. However, a turning point is observed when these parameters are evaluated in terms of the inlet Reynolds number. At low Reynolds numbers, both the heat transfer coefficient and the friction factor remain relatively stable, notwithstanding fluctuations in static pressure. Conversely, at higher Reynolds numbers, a reduction in static pressure negatively influences these factors. For instance, when the static pressure is 10 kPa, the associated Reynolds number is 500. Nevertheless, the Reynolds number at which this turning point occurs escalates with an increase in static pressure.

Deep syntectonic burial of the Anthracite belt, Eastern Pennsylvania

Fluid inclusion microthermometry and Raman spectroscopy of fluid inclusions in quartz veins from the Pennsylvanian rocks of the Anthracite belt, eastern Pennsylvania support a deep burial model of coalification in favor of focused orogenic hot fluid flow. High-temperature (250 to 255 °C) trapping of CH4 ± CO2 saturated aqueous fluids and CH4 ± CO2 inclusions indicate fluid trapping at depths of 11.5 to 13.4 km under a cover of Pennsylvanian to Permian(?) syntectonic load. In the folded rocks to the south of the Anthracite belt, CH4 ± CO2 fluid inclusions indicate a sediment load that was up to 16.3 km thick. Re-equilibrated aqueous fluid inclusions from veins in Silurian through Devonian rocks give the same range of trapping conditions but a wide range of fluid salinities suggesting that folding, fracturing, and meteoric recharge resulted in the intermixing of fluids from throughout the stratigraphic succession.

Exergetic analysis and multiparametric optimization of a novel three‐fluid‐based organic Rankine cycle evaporative system via Taguchi method

AbstractEvaluations were conducted on the thermal performance of an organic Rankine cycle (ORC) system using three fluids as the evaporative system at a low‐grade heat source. The modified ORC evaporators were replaced with a three‐fluid system, which included hot fluids at the top and bottom and an isopentane working fluid in the middle section. Furthermore, the thermal performance assessment with a hot fluid heat transfer ratio in the outer and inner tubes (Q2/Q1) varying from 25:75 to 75:25 has been investigated. The impact of the hot fluid's (Q2/Q1) heat transfer ratios to saturated steam on the modified ORC's thermal performance assessment was examined, with an evaporative temperature range of 45–65°C and a pinch point temperature difference (PPTD) of 3–10°C. The Taguchi technique solves multiparameter optimization using the L9 orthogonal array. The findings showed that in three‐fluid‐based modified ORC systems, the network output, exergetic efficiency, and irreversibility went down with PPTD for all three Q2/Q1 cases. For Q2/Q1 of 75:25, the ORC's energetic efficiency and overall irreversibility reached their optimum, while a PPTD of 3–10°C reduced the exergetic efficiency by 19.71%. Also, Q2/Q1 of 75:25 showed the highest and 200% higher ORC system work done at PPTD of 3°C than Q2/Q1 of 25:75—the lowest. Modified ORC network generation, energy output, and heat transfer rate showed excellent results at an evaporative temperature of 58.33°C. For optimal network productivity, Q2/Q1 of 75:25 was 160% and 40% greater than 50:50 and 25:75 at 58.33°C, respectively. The three‐fluid‐based modified ORC system performs better with a 75:25 Q2/Q1 ratio. According to Taguchi's analysis, evaporation temperature affects the improved ORC system's thermal, exergy, and network generation. Also, heat transfer ratios (F = Q2/Q1) largely affect system irreversibility.