Heat Transfer Process Research Articles

Heat transfer characteristics during bottom-blown bubble coalescence

Bubble swarm evolution and behaviors are the key to study the heat transfer between a bubble swarm and its surrounding flow field, and are of significant and systematic theoretical guidance for exploring the process reinforcement technology and processes. In this study targeted at Therminol®66 and R245fa, we analyzed the three factors affecting gas-liquid two-phase flow. The results show that the flow rate of the dispersed phase has a significant effect on the heat transfer coefficient. When the flow rate of the working medium increases from 0.4 kg s-1 to 0.8 kg s-1, the heat transfer coefficient increases by about 1.25 times. The initial temperature difference is positively correlated with the heat transfer coefficient, but the continuous phase height increases the heat transfer coefficient first and then decreases. The heat transfer coefficient model is in good agreement with the results of Kwon, and the deviation is within 20 %, accounting for 92.464 %, which can be further used to describe the heat transfer process of heat exchanger or bottom-blown melting pool. Correlation equations for the Nusselt number (Nu) is developed, with average absolute deviation of 18.49 %.

Analysis of the tri-hybrid Maxwell nanofluid flow with temperature-dependent thermophysical characteristics on static and dynamic surfaces employing Levenberg-Marquardt artificial neural networks

Using the Levenberg-Marquardt Artificial Neural Network (LM-ANN) model, this study applies computational neuroscience to the analysis of flow, heat, and mass transport characteristics. The novel characteristics of MHD Maxwell tri-hybrid nanofluid passing through static and moving wedge with temperature-dependent thermophysical properties (thermal conductivity, viscosity, diffusivity, and electrical field) in permeable, radiative, and mixed convection processes are investigated in this paper. Nonlinear PDEs are transformed into nonlinear ODEs using similarity variables. A dataset for the LM-ANN is generated across various scenarios by varying parameters such as the temperature-dependent viscosity parameter ( 0.07 − 0.1 ) , variable diffusivity parameter ( 0.4 − 2.5 ) , thermal buoyancy parameter ( 0.1 − 0.5 ) , nonlinear thermal buoyancy parameter ( 0.2 − 0.5 ) , thermal radiation ( 1 − 1.5 ) , buoyancy ratio parameter ( 0.2 − 0.5 ) , chemical reaction parameter ( 1 − 3 ) , and Schmidt number ( 1 − 3 ) using the Bvp5c numerical algorithm. The testing, training, and validation procedure of LM-ANN is utilized to examine the estimated solutions of specific situations, and the proposed algorithm is then validated. After that, the proposed LM-ANN is validated using regression analysis, MSE, and histogram analysis. The prescribed approach impeccably mirrors the recommended and cited findings, evincing a precision level within the realm of 10−9. Results indicate that increasing the permeability parameter from 1 to 1.2 and the temperature-dependent thermal conductivity parameter from 0.4 to 2.5 enhances the Nusselt number. Additionally, increasing the chemical reaction parameter from 1 to 3 leads to an increase in the Sherwood number. The significance of this study lies in its potential applications in industries such as aerospace, chemical processing, and energy systems, where efficient heat and mass transfer processes are crucial. For instance, the findings can be applied to enhance cooling techniques in high-performance aerospace components, optimize reactor designs in chemical plants, and improve thermal management in power generation systems.

Geothermal energy appraisal and subsurface structural mapping of the Rafin Rewa warm spring region, Precambrian basement complex of Nigeria

This research work aims at evaluating the geothermal energy potentials of the Rafin Rewa warm spring (RRWS) of the Precambrian Basement Complex in Nigeria as an alternative energy source using integrated aeromagnetic geophysical techniques. Four aeromagnetic dataset were acquired, assemblage, analyzed, and interpreted using integrated geophysical processing techniques of spectral analysis and Euler deconvolution. Qualitative interpretation of the residual anomalous map reveals a distribution of positive anomalies (> 53 nT) majorly in the central and southeastern regions, which are traced to the granitic rocks, while the low anomalies (< − 1.5 nT) have been traced to the RRWS location emanating from the coastal plain sands of the Pliocene, Pleistocene, Oligocene, and Miocene ages. Quantitatively, the depth to the top (DTT) of the anomalous bodies reveals a depression that is almost intersecting with the Curie point depth (CPD) plot at the RRWS location, which indicates high heat flow in the RRWS region. The Spectral Analysis results reveal that the DTT and the CPD in this area ranges from 0.512 to 0.761 km and 6.504 to 10.582 km, respectively while the average CPD is 8.543 ± 0.325 km. It is observed that the DTT and CPD decrease as one move away from the RRWS region. The computed heat flow average was 160.76 ± 19.09 mW/m2 within the RRWS region. The Euler deconvolution result reveals the presence of geological structures, which were interpreted as faults and fractures. The major fractures trend in the east–west (E-W) directions, while the minor fractures trend northeast-southwest (NE-SW) directions. The geochemical result presented shows that iconic compositions impact the convective heat transfer processes associated with geothermal systems. It was conclusively believed that regions with comparable shallow CPDs could be viable for further geothermal energy investigations.

Natural convection heat transfer in an eccentric annulus filled with hybrid nanofluid under the influence of thermal radiation and heat generation/absorption

This investigation aims to scrutinize the flow and heat transfer characteristics of a hybrid nanofluid composed of Ag-MgO within an eccentric annular space, where the inner circular wall is held at a constant elevated temperature and the outer circular wall is uniformly cooled. Natural convection in such eccentric annular enclosures, with thermal radiation and the effects of heat generation/absorption taken into consideration, plays a vital role in various engineering applications, including solar collectors, nuclear reactors, thermal storage systems, and heat exchangers. The resolution of the fundamental governing equations was executed employing the Gauss-Seidel approach, with the inclusion of a sub-relaxation process, all within the framework of the finite volume method. The impact of the Rayleigh number, radiation number, volume fraction as well as heat generation/absorption coefficient on thermal transfer, flow, and temperature distributions were investigated. It was observed that for low Rayleigh numbers, radiation influences enhance flow stability and improve the conductive heat transfer mode. Conversely, at high Rayleigh numbers, radiation intensifies convective heat exchange. The growth of the Rayleigh number diminishes the impact of heat generation and reinforces the radiation heat transfer process, while heat absorption exhibits the opposite effect. From Nr = 1 onwards, the average Nusselt number values are no longer influenced by an increase in nanoparticle volumetric fraction, and they are solely linked to the radiation number.

De-icing behavior and efficiency of electrothermal film surfaces with different non-wettability in low-temperature flow field

The electrothermal anti-/de-icing technology with excellent de-icing efficiency has been widely applied to eliminate the icing threat on airfoil, whose essence is heat transfer process between heating surface and ice. However, the heat transfer behavior and interfacial transformation form of ice accretion are indistinct on traditional non-superhydrophobic surfaces and rapidly-developed superhydrophobic surfaces in the low-temperature flow field. Therefore, the heat transfer and solid-ice interface transform behavior on film heater surface were explored in this work by analyzing the temperature-rising performance and de-icing characteristics of hydrophobic films (HPoF) and superhydrophobic films (SHPoF) in the icing wind tunnel. The results indicated that the faster wind speed enhanced the convection and radiant heat loss of the film heater, and the peak temperature of film heater was directly affected by the environment temperature. Moreover, the SHPoF had lower de-icing consumption than HPoF in an environment without wind field, which was less related to the ice accretion. However, the de-icing form transformed from shearing to shedding mode with the growth of ice accretion under wind field conditions. In the shearing de-icing mode, the lower environment temperature and faster wind speed caused longer de-icing time, whereas the deicing time shortened with the decrease of environment temperature in the shedding mode. When the icing time was 1 min, the de-icing time of SHPoF increased by 12.25%–25.73 % due to the slower heat transfer at the solid-gas-ice interface compared to the solid-liquid-ice interface of HPoF. With the further increase of icing time, the ice accretion was removed after the melt of interfacial ice. The less solid-ice contact points were present at the solid-gas-ice interface on SHPoF surfaces, resulting in energy saving of 20.16%–40.46 % compared to HPoF surfaces. Therefore, the electrothermal superhydrophobic de-icing technology exhibited energy-efficient characteristics when the self-weight of ice is the primary driving force for de-icing process.

Heat transfer processes in 'Shine Muscat' grapevine leaves in solar greenhouses under different irrigation treatments

The use of solar greenhouses in China is increasing because they permit environmental conditions to be controlled. Studies of the heat transfer processes in the leaves of plants cultivated within solar greenhouses are needed. Here, we studied heat transfer processes in 'Shine Muscat' grapevine leaves under moderate deficit irrigation (MDI), severe deficit irrigation (SDI), and full irrigation (FI) treatments under varying weather conditions. The stomatal conductance, leaf temperature, and transpiration rate of both shade and sun grapevine leaves were measured, and the effects of ambient temperature and relative humidity on these variables were determined. A thermal physics model of the leaves was established to explore the heat dissipation process. On sunny days, the transpiration heat transfer of sun leaves in the MDI, SDI, and FI treatments was 2.62 MJ m−2·day−1, 2.44 MJ m−2·day−1, and 3.86 MJ m−2·day−1and 0.818 MJ m−2·day−1, 0.782 MJ m−2·day−1, and 1.185 MJ m−2·day−1 on rainy days, respectively. There was a significant difference in transpiration heat transfer under fully irrigated and deficit irrigation conditions under different weather conditions. Furthermore, transpiration heat transfer accounted for 41.49 % and 25.03 % of the total heat transfer of sun leaves in the FI treatment and 33.94 % and 29.43 % of the total heat transfer of shade leaves on rainy days, respectively, indicating that relative humidity plays a key role in determining transpiration heat transfer and leaf temperature and that its effect was greater on sun leaves than on shade leaves.

Influences of ultra-low load operation strategies on performance of a 300 MW subcritical bituminous coal boiler

To reveal the operational characteristics of subcritical boilers under ultra-low loads, numerical simulations were conducted based on a 300 MW subcritical bituminous coal boiler. The impacts of boiler load and low-load operation strategies on coal combustion behavior, heat transfer process, and NOx emission were thoroughly examined. Results indicate that acceptable aerodynamic and temperature fields can still be formed at 25 % ultra-low load, but the boiler performance is significantly reduced, with the maximum cross-sectional average combustion temperature being reduced by 225.98 K compared with the full-load condition. At 25 % load, the use of only two layers of burners results in a substantial increase in NOx emission from 290.32 mg/m3 to 445.56 mg/m3. The position of in-service burners affects the region where the intense coal combustion and heat release process occurs, and using the middle three layers of burners helps to maintain heat absorption by the suspended heating surfaces and to minimize NOx emissions. Furthermore, increasing primary air velocity at ultra-low loads can promote coal combustion and heat transfer processes in the lower furnace, but increase NOx emission by 14.23 % when primary air velocity is increased from 14.90 m/s to 23.00 m/s at 25 % load. These findings provide valuable insights for optimizing the ultra-low load operation of subcritical boilers engaged in deep peak-shaving processes under the carbon neutrality goal.

Nanoparticle agglomeration in molten salt nanofluids: Free energy landscape and its impacts on thermal transport property degradation

The nanofluids consisting of molten salt and nanoparticles can gain enhanced thermal performance for heat transfer and energy storage processes. Agglomeration of nanoparticles is ubiquitous in this colloidal dispersion, deteriorating the dispersed states of the nanocomposite interiors, and its microscopic mechanisms are unsatisfactorily explored. In this work, molecular dynamics simulations combined with umbrella sampling technique to capture the relative dispersion state of nanoparticles in molten salts effectively were performed to reveal the free energy landscape of agglomeration and its influence on heat transport. The dominant deep minima in the free energy surface demonstrates that the agglomeration of MgO nanoparticles in the molten NaCl salt is principally induced by van der Waals attractions between MgO nanoparticles and aggravated by large surface area. The unstable dispersion of nanoparticles is the most fatal problem for enhanced thermal conductivity during agglomeration, and the relative distance of MgO nanoparticles has less impacts on the thermal conductivity of the melt. The stronger adsorption of ions around nanoparticles can improve their relative dispersion, and utilize interfacial effects to enhance the thermal conductivity. Combined with the benefit of ordered ionic layer on the surface, the MgO nanoparticles of 10 Å diameter (specific surface area of ∼ 938.80 m2/g) become the optimal choice for molten NaCl. With the mechanisms of interfacial microstructures preventing agglomerated nanoparticles and improving heat transfer of molten salts revealed, this work can enlighten the selection or feasible modification for nanoparticles in various high-temperature molten salts, since the mechanisms are universal to other nanofluids, especially for ionic liquid based nanofluids.

Influence of temperature dependent short-term storage on thermal runaway characteristics in lithium-ion batteries

In practical applications, lithium-ion batteries inevitably encounter short-term exposure to high or low temperatures due to geographical climate variations and specific usage scenarios. This study explored the impact of short-term storage at temperatures ranging from −40 to 60 °C on the thermal stability of batteries. Combustion behavior, onset time (tTR) and onset temperature (TTR) of thermal runaway (TR), flame heat flux and mass loss were measured. It demonstrates that following short-term high/low temperature storage, the amount of gas in the exhaust phase increased significantly, and the intensity of the flame jet was enhanced. The experimental results showed that the tTR and TTR initially increased and then decreased with the storage temperature decreased from 20 °C to −40 °C. High temperature storage led to earlier TR and lower TTR. Interestingly, storage at 0 °C caused a delay in the occurrence of TR. Furthermore, an analysis of the heat transfer process, spanning from the safety valve opening to the onset of TR, was performed by leveraging the characteristic time and temperature parameters observed during the TR process. The findings of this research contribute to enhancing the safety and reliability of battery applications, particularly in scenarios involving temperature variations and potential thermal risks.

The Identification of Leidenfrost Phenomenon Formation on TiO2-Coated Surfaces and the Modelling of Heat Transfer Processes.

Experiments on specimen cooling dynamics and possible film boiling around a body are very important in various industrial applications, such as nucleate boiling, to decrease drag reduction or achieve better surface properties in coating technologies. The objective of this study was to investigate the interaction between the heat transfer processes and cooling dynamics of a sample in different boundary conditions. This article presents new experimental data on specimens coated with Al-TiO2 film and Leidenfrost phenomenon (LP) formation on the film's surface. Furthermore, this manuscript presents numerical heat and mass transfer parameter results. The comparative analysis of new experiments on Al-TiO2 film specimens and other coatings such as polished aluminium, Al-MgO, Al-MgH2 and Al-TiH2 provides further detail on oxide and hydride materials. In the experimental cooling dynamics experiments, specimens were heated up to 450 °C, while the sub-cooling water temperatures were 14*‒20 °C (room temperature), 40 °C and 60 °C. The specimens' cooling dynamics were calculated by applying Newton's cooling law, and heat transfer was estimated by calculating the heat flux q transferred from the specimens' surface and the Bi parameter. The metadata results from the performed experiments were used to numerically model the cooling dynamics curves for different material specimens. Approximated polynomial equations are proposed for the polished aluminium, Al-TiO2, Al-MgO, Al-MgH2 and Al-TiH2 materials. The provided comparative analysis makes it possible to see the differences between oxides and hydrides and to choose materials for practical application in the industrial sector. The presented results could also be used in software packages to model heat transfer processes.

Influence of the Presence of Different Signatures on the Heat Transfer Profile of Laminar Flow Inside a Microchannel

Abstract The process of transferring heat and mass involves a high-pressure decline. Hence microchannels are utilized in extremely efficient heat and mass transfer processes, such as in the systems of the lungs and kidneys. Due to their high surface-to-volume ratio and compact volume, microchannels have demonstrated superior thermal performance. In this work, micro-fins of different topologies and arrangements were used inside microchannels for modulating heat transfer from the surface of the fins, in the presence of flowing media. The influx of media was simulated in sinusoidal form, reproducing simplified form of physiological circulatory blood flow. The study was conducted in numerical domain, while heat transfer and mass transfer equations were solved using pardiso solver. Temperature modulation at the fin surfaces was conducted to examine the transient profile of heat transfer, as function of both variable fluid velocity as well as variable feeding heat sources. In case of different input boundary conditions, the effect of heat distributions on fluid flow with respect to spatial distribution of micro-fins within a microchannel was evaluated. Results revealed the difference in heat transfer profiles in microchannels in presence of different sets of fin configurations. It was found that rectangular fins have the highest heat transfer in fluid at all its spatial configurations; while semi-ellipsoidal-shaped fins had shown the least heat transfer profile at same surface area. At the same time, it was also observed that the rate of heat dissipation was faster and limited in semi-ellipsoidal-shaped fins configuration; while the heat transfer rate was found symmetrical and low in presence of rectangular fins. Hence, this article emphasizes the modulation of temperature and velocity variations within the working fluid by emphasizing the thermo-fluid coupling effects in microchannels.

A novel oscillating flow cycle engine with characteristics of temperature glide heat addition and no regenerator for low-grade heat utilization

In oscillating flow cycle engines such as Stirling engines, nearly isothermal heat additions in heat exchangers will produce irreversibility losses during the heat transfer processes and the regenerator is indispensable and expensive. Thus, it reduces oscillating flow cycle engine’s economic attractions for low-grade heat utilization. In this work, three structures of one-way oscillating flow cycle engine are proposed for overcoming these problems. To assess the feasibility, one structure is chosen for analysis. Then, a one-dimensional computational fluid dynamic model considering various heat transfer and flow friction losses is developed. Based on the validated model, performance analysis is carried out. The temperature glide for heat absorption can reach up to 116 K and can be adjusted. The obtained maximum thermal efficiency is 7.79 %, 12 %, and 14.6 % respectively for low-grade heat’s inlet temperatures of 373 K, 423 K, and 473 K. Furthermore, the maximum specific work output for 1 kg/s hot water is 13.7 kW, 36.9 kW and 64.4 kW respectively at an inlet temperature of 373 K, 423 K, and 473 K, with corresponding maximum exergy efficiency of 42.8 %, 43.7 % and 41.1 % respectively. Thus, the results demonstrate that large temperature glide heat addition can be achieved, and a novel oscillating flow cycle engine without a regenerator is feasible and efficient.

Sintering Kinetics and Interfacial Heat Transfer Process of Binary Alloy Nanoparticles Catalysts: Molecular Dynamics Simulation

Sintering Kinetics and Interfacial Heat Transfer Process of Binary Alloy Nanoparticles Catalysts: Molecular Dynamics Simulation

Experimental Study on Convection Heat Transfer of CO2 in C/SiC Composite Porous Material at Subcritical, Transcritical, and Supercritical States

Using C/SiC as the structure for transpiration cooling is prospective for new hypersonic vehicles, based on clarification of heat transfer process in porous media. But there are still gaps due to the complexity of pore structure of C/SiC, together with the effects of capillary force and strong variation of thermophysical properties for subcritical and supercritical flow. In this study, heat transfer analysis for C/SiC with CO2 as the coolant is presented by experiments. Heat transfer characteristics in typical C/SiC sample under various mass flow rates (0.003–0.018 kg/s), inlet fluid temperatures (20–40 °C) and pressures (5.9–10 MPa) are analyzed. Heat transfer and pressure drop correlations have been developed. The results show heat transfer coefficient at supercritical state behaves non-monotonic under varying flow rates caused by the combined effect of sharp increase of specific heat and the change of flow rate. The effect of pressure on heat transfer can be neglected compared to that of flow rate, while for Reynolds number (Re) >100, the pressure drop of supercritical cases are smaller than that of phase-change cases under similar Re, due to the effect of capillary force in C/SiC. This study can provide basic support for further study of transpiration cooling using C/SiC and CO2.

CFD and RSM Assist in Reducing the LPG Consumption of Burners for Agarwood Oil Production in Thailand

ABSTRACT This research aimed to optimize LPG consumption in Thai commercial burners used in agarwood oil production, specifically focusing on the KB-10, S-10, and EB-10 burners. Enhancing burner efficiency is crucial due to rising energy costs and environmental concerns. A dual approach using Response Surface Methodology (RSM) and Computational Fluid Dynamics (CFD) was employed in order to achieve the best burner. Central Composite Design (CCD) within the RSM framework determined the optimal swirl and inclination angles combinations. Modified burners with variant combination angles, as suggested by RSM, were numerically investigated. CFD simulations with Ansys Fluent, utilizing the k-ε turbulence and discrete ordinates (DO) radiation models, provided detailed insights into the combustion and heat transfer processes of those modified burners. The modified burners, SB10–1, SS10–3, and SEB10–7, demonstrated significant improvements. Laboratory and field tests indicated energy savings of 16.15%, 23.74%, and 20.75%, respectively. Statistical analysis confirmed these savings with p-values < .05. The 95% confidence intervals for LPG savings were 31.31 ± 0.8%, 33.42 ± 0.7%, and 31.84 ± 0.6%, corresponding to payback periods of approximately 2.99, 4.21, and 8.95 months. Additionally, CO and NOx emissions were kept below 350 ppm and 100 ppm, respectively. The novelty of this study lies in the combined use of RSM and CFD to optimize burner performance, leading to significant energy savings and emission reductions. These findings highlight the potential of these methods for burner optimization, offering both economic and environmental benefits. This research underscores the importance of integrating advanced modeling techniques to achieve sustainable and cost-effective industrial processes.

Numerical investigation of the sensible heat storage in novel electrostatic precipitators with liquid-filled collection electrodes

Heat recovery from flue gas holds significant potential for energy conservation. A strategy is proposed for recovering and storing heat in electrostatic precipitators by utilizing liquid-filled collection electrodes. In the prototype, the hollow collection electrode is connected to the heat storage tank. Convective heat transfer occurs between the gas stream and the liquid contained in the collection electrode. The heat storage mechanism is revealed by numerical simulation of corona discharge, flow and heat transfer processes in a simplified electrostatic precipitator. The results indicate that both the gas-side and liquid-side heat transfer coefficients reach steady values within approximately 100 s. The buoyancy-driven liquid flow results in a heat transfer coefficient that is 28 times higher than that for gas-side forced convection. Increasing the gas inlet temperature leads to a greater buoyancy force and, consequently, a higher heat transfer coefficient on the liquid side. Both ionic wind and inlet velocity affect the gas-side heat transfer. The ionic wind disturbs the thermal boundary layer, leading to a 27.9 % increase in the gas-side heat transfer coefficient at an inlet velocity of 0.5 m/s. Furthermore, this enhancement becomes more pronounced as the inlet velocity decreases. The flow pattern of liquid in the collection electrode and heat storage tank is crucial to the heat storage process. Additionally, installing the heat storage tank above the electrostatic precipitator provides added benefits. During the process of heat storage, the largest heat resistance is found on the gas side.

Scintilla: Simulating Combustible Vegetation for Wildfires

Wildfires are a complex physical phenomenon that involves the combustion of a variety of flammable materials ranging from fallen leaves and dried twigs to decomposing organic material and living flora. All these materials can potentially act as fuel with different properties that determine the progress and severity of a wildfire. In this paper, we propose a novel approach for simulating the dynamic interaction between the varying components of a wildfire, including processes of convection, combustion and heat transfer between vegetation, soil and atmosphere. We propose a novel representation of vegetation that includes detailed branch geometry, fuel moisture, and distribution of grass, fine fuel, and duff. Furthermore, we model the ignition, generation, and transport of fire by firebrands and embers. This allows simulating and rendering virtual 3D wildfires that realistically capture key aspects of the process, such as progressions from ground to crown fires, the impact of embers carried by wind, and the effects of fire barriers and other human intervention methods. We evaluate our approach through numerous experiments and based on comparisons to real-world wildfire data.

Cyclogenesis: Simulating Hurricanes and Tornadoes

Cyclones are large-scale phenomena that result from complex heat and water transfer processes in the atmosphere, as well as from the interaction of multiple hydrometeors , i.e., water and ice particles. When cyclones make landfall, they are considered natural disasters and spawn dread and awe alike. We propose a physically-based approach to describe the 3D development of cyclones in a visually convincing and physically plausible manner. Our approach allows us to capture large-scale heat and water continuity, turbulent microphysical dynamics of hydrometeors, and mesoscale cyclonic processes within the planetary boundary layer. Modeling these processes enables us to simulate multiple hurricane and tornado phenomena. We evaluate our simulations quantitatively by comparing to real data from storm soundings and observations of hurricane landfall from climatology research. Additionally, qualitative comparisons to previous methods are performed to validate the different parts of our scheme. In summary, our model simulates cyclogenesis in a comprehensive way that allows us to interactively render animations of some of the most complex weather events.

A fully coupled thermo-poroelastic model for energy extraction in naturally fractured geothermal reservoirs: sensitivity analysis and flow simulation

The development of a novel method for modelling fluid flow and heat transfer in naturally fractured geothermal reservoirs represents a significant advancement in geothermal energy research. This Study presents a hybrid approach, which combines discrete fracture and single continuum techniques, to effectively capture the complex interactions between fluid flow and heat transfer in geothermal fractured reservoirs. In addition, the incorporation of the local thermal nonequilibrium method for simulating heat transmission accounts for the disparities in temperature between the rock matrix and the fluid, providing a more realistic representation of heat transfer processes. The study also presents a fully coupled thermo-poro-elastic framework that integrates fluid flow and heat transfer to comprehensively evaluate reservoir responses to injection/production scenarios. This coupled approach allows for the prediction of changes in reservoir properties, such as permeability and porosity, under varying fluid pressure and temperature conditions. The application of the proposed model to evaluate a geothermal reservoir’s long-term response to injection/production scenarios provides valuable insights into the reservoir’s behaviour and potential energy production capacity. The sensitivity analysis further enhances the model’s utility by identifying the key reservoir parameters that significantly influence the thermal depletion of the reservoir. Overall, this novel modelling approach holds promise for improving the understanding and management of naturally fractured geothermal reservoirs, contributing to the optimization of geothermal energy extraction strategies.

Analytical modelling of an indirect evaporative cooler based on the Maisotsenko cycle for HVAC applications

Highly-efficient evaporative cooling systems can significantly reduce the energy use in buildings, thereby contributing to meet Europe’s climate commitments, including building decarbonisation by 2050. The Maisotsenko Cycle is an indirect, multi-stage type of evaporative cooling which can be used in different air-conditioning applications. The main objective of this study is to develop an analytical model of an indirect evaporative cooler based on the Maisotsenko cycle for HVAC applications. The conservation equations governing the heat and mass transfer processes occurring in the indirect evaporative cooler were solved by means of numerical methods, and the results provided by the model were validated using experimental data reported in the literature (differences lower than 2%). Finally, a parametric study was conducted where the influence of various operational and environmental variables on the system's performance were numerically analysed.