Thermal Oil Research Articles

High-Pressure Pasteurization of Oat Okara.

The issue of the short microbiological shelf life of residues from the plant-based beverage industry creates a large food waste problem. Today, the oat beverage residue, in this study referred to as oat okara, is generally converted to energy or used as animal feed. High-pressure pasteurization (200 MPa, 400 MPa, and 600 MPa) was applied to oat okara to investigate the effect on shelf life and microbiological activity. A 4-week microbiological storage study was performed and thermal properties, viscosity, and water and oil holding capacities were analyzed. The total aerobic count, including yeast and mold, was significantly reduced (p < 0.05) by 600 MPa after four weeks of storage at 4 °C. The content of lactic acid bacteria after four weeks of storage was low for untreated oat okara (3.2 log CFU/g) but, for 600 MPa, the content remained at the detection limit (2.3 log CFU/g). Conversely, the treatments of 200 MPa and 400 MPa increased the microbial content of the total aerobic count significantly (p < 0.05) after two weeks in comparison to untreated oat okara. The thermal properties of untreated and high-pressure-treated oat okara demonstrated an increase in protein denaturation of the 12S globulin, avenalin, when higher pressure was applied (400-600 MPa). This was also confirmed in the viscosity measurements where a viscosity peak for avenalin was only present for untreated and 200 MPa treated oat okara. The water holding capacity did not change as a function of high-pressure treatment (3.5-3.8 mL/g) except for the treatment at 200 MPa, which was reduced (2.7 mL/g). The oil holding capacity was constant (1.2-1.3 mL/g) after all treatments. High-pressure pasteurization of 600 MPa reduced the microbial content in oat okara resulting in a shelf life of 2-4 weeks. However, more research is required to identify the microorganisms in oat okara to achieve a microbiologically safe product that can be used for food applications.

Finite element analysis of laser welding of 304L butt joint

Grade 304L is an Austenitic stainless steel, which is popular for different high temperature application like Nuclear power plants, thermal power plants and oil & Gas industries etc. In this paper, FEM based investigation was carried out for 1.2 mm thick 304L stainless steel welded using Laser welding process. Thermal cycle was measured at 10 mm distance from welding centerline using K type thermocouple compared with predicted values. FEM based thermal analysis was carried out using SYSWELD. Two different heat source models were selected for laser heat source distribution modeling, conical and double ellipsoidal model are selected. Predicted model has been validated experimental weld profile, results showed a good accuracy of conical model.

Enhancing Burner Efficiency on Marine Vessels: A SWOT Analysis Approach

As the main heat source on board, the Thermal oil heater has a burner that is responsible for the combustion process. The burner has an important role in the operation of the Thermal oil heater. However, several problems were found in its operation, such as decreased performance and inefficient maintenance on the burner, which caused obstruction of ship operations and had an impact on company losses. This study aims to find a performance strategy for the burner to operate optimally. Based on the burner manual book found on the ship and the theory put forward by experts, This research is a qualitative study, using the SWOT method to analyze internal and external factors. To find out the cause of the decline in burner performance and also to find out the right maintenance management to prevent degradation of the burner. This research used observation, interviews, literature reviews, and documentation for data collection. Based on the author's observations using findings, manual books, and several related journals as data sources, he also interviewed several crew members as validators as well as for comparisons. This research concludes that by maximizing maintenance time and the accuracy of maintenance time according to the running hours in the manual book, The importance of maintenance has a significant influence on the optimization of the burner, but coordination with the maintenance team is also important.

Effects of variable thermal conductivity and curvature parameter on the peristalsis of hybrid nanofluid through a curved channel with curvature dependent channel walls

This study focused on the peristaltic motion of hybrid nano-liquid via a curved geometry with curvature-dependent channel walls. The hybrid nanofluid is composed of alumina (Al2O3) nanoparticles mixed with multi-wall carbon nanotubes (MWCNTs) and suspended in thermal oil. This combination is based on an experimental examination conducted by Asadi et al. [58]. Keeping in view the industrial applications of such flows, the hybrid nanofluid thermal conductivity is considered to vary with temperature. Furthermore, heat sink/source is also taken into account in the energy equation. Lubrication approximation is utilized to simplify the flow problem. The resulting model is treated using a numerical scheme NDSolve based on the shooting method (“a built-in command in Mathematica”). The primary focus remains on analyzing the impacts of the curvature parameter, flow rate, and variable thermal conductivity parameter. Outcomes indicate that there is a critical “flow rate” value for such a type of channel. The thermal transfer rate increases with an improvement in the values of the curvature parameter. Furthermore, graphical results reveal that hybrid nanofluid’s temperature decreases for higher values of flow rate, while it rises with heat generation/absorption parameter. It is observed that temperature of the hybrid nanofluid increases as the values of curvature parameter improve. A higher flow rate reduces the rate of heat transfer. It is also noted that velocity profile remains constant at a flow rate value of 7.40. Moreover, the variable thermal conductivity has a remarkable impact on temperature profile.

Joint data reconciliation and artificial neural network based modelling: Application to a cogeneration power plant

This contribution represents a practical application of predictive thermal modelling of an existing cogeneration plant. The analysed cogeneration plant consists of a gas turbine coupled to a heat recovery steam generator, which produces two streams of superheated steam (65 bar and 10 bar) and a thermal oil stream at 350 °C. The proposed model was based on an artificial neural network and was trained using real operational data. However, although data acquisition systems currently used in power generation plants allow for the recording of multiple measurements using small sampling intervals, this does not guarantee a satisfactory analysis of operational data. Therefore, the potential of artificial neural networks can result in incorrect or imprecise results if the calibration of the network is performed with inconsistent or highly uncertain datasets. The novelty of this work consisted on the application of data reconciliation to the real dataset before the model training, in order to minimize the typical uncertainty associated with plant instrumentation measurements. The results obtained demonstrated the advantage of training the network with reconciled data and that modelling error is reduced for all analysed outputs when the model is based on artificial neural networks instead of polynomial models.

Optimization of a Solvay cycle-based liquid air energy storage system

Liquid air energy storage systems (LAES) are being built as an alternative to battery storage to address the intermittent nature of renewable energy sources. In this work, optimization of the LAES operating on a Solvay cycle is performed to determine the best possible operating conditions and round-trip efficiency of the process. The simulation model of the process accounts for the non-linear variation of heat capacity of air, propane, methanol, and thermal oil and the occurrence of internal temperature pinches in the heat exchangers. The optimization results in this work show that the ‘sweet spot’ operating regime corresponds to a charging pressure between 130 and 190 bar and a discharging pressure between 70 and 120 bar, resulting in a round trip efficiency (ηRTE) of more than 60%.

Reducing CO2 emissions and improving oil recovery through silica aerogel for heavy oil thermal production

Heavy oil reserves comprise more than 60% of global crude oil resources, and thermal oil recovery techniques, especially steam injection, are widely utilized for extracting heavy oil. However, these thermal production processes are characterized by high energy consumption and carbon emissions, which pose significant challenges in reducing CO2 emissions. In response to these challenges, this study presents a novel approach that combines silica aerogel with CO2-assisted thermal recovery technology. Our findings demonstrate that the incorporation of aerogel nanoparticles enhances the adsorption capacity of CO2 in the aqueous phase. The adsorption behavior of CO2 in silica aerogel aligns with the Langmuir model. When silica aerogel nanoparticles are employed in steam flooding, a notable improvement is observed in both oil recovery and CO2 sequestration rate. Molecular dynamics simulations reveal that the porous structure of aerogel enables the adsorption of light saturates molecules from crude oil, promoting their diffusion into the aqueous phase and ultimately enhancing oil recovery. The steam condensation experiments clearly demonstrate that the presence of aerogel and CO2 exerts a substantial influence on the condensation heat transfer of steam, resulting in a reduction in the condensation heat transfer rate between the steam and the cooling wall. Additionally, molecular dynamics simulations reveal that silica aerogel nanoparticles exhibit an affinity for adsorbing onto hydrophobic quartz surfaces, forming an insulating layer between steam and quartz, thereby facilitating CO2 sequestration. The introduction of silica aerogel nanoparticles expands the swept volume of steam heat. This study provides valuable insights into the underlying mechanisms responsible for improved CO2 sequestration and increased oil recovery through the implementation of silica aerogel nanoparticles, offering fresh perspectives on heavy oil recovery.

Performance comparison of PTCs with nanoparticles in water and nanoparticle in thermal oil

The use of nanoparticles to improve the thermal efficiency of PTCs has become a popular area of research. In this study, we present a comparative analysis of the effects of nanoparticles on the thermal performance of PTCs using water and thermal oil as heat transfer fluids. To obtain accurate temperature estimates, we developed a mathematical model that considers heat transfer in both axial and radial directions. The model includes a two-phase flow homogenous model for the liquid phase, as well as nanoparticle concentration, to achieve the best temperature estimation. We validated our model using experimental data and found that the maximum relative error was 2.3% for water and a lower error of 1.5% for thermal oil. Our analysis of thermal efficiency and exergetic efficiency showed that the addition of Al2O3 nanoparticles led to greater improvements in the thermal efficiency for water, even at the same range of nanoparticle concentration. Furthermore, our results demonstrated that exergetic efficiency was generally higher for water than for thermal oil. Overall, this study highlights the potential benefits of using nanoparticles to enhance the thermal efficiency of PTCs. Our findings could help guide the design and optimization of PTC systems in various applications.

Improving IEC thermal model for oil natural air natural transformers using optimised parameters based on dynamic simulation

AbstractAccurate assessment of hot‐spot temperature is essential for the safe operation of power transformers. Existing dynamic thermal models cannot estimate hot‐spot temperature accurately since some input parameters are roughly determined by transformer capacity and cooling mode while ignoring the effect of winding structure, tank dimensions, and material physical properties. To improve the accuracy of temperature assessment, empirical parameters of the IEC thermal model including thermal constants, winding and oil exponents are optimised with the help of numerical simulation in this article. Based on energy conservation and heat transfer theory, a computational fluid dynamic (CFD) model of a transformer in oil natural air natural (ONAN) cooling mode is established. This CFD model simulates the entity's structure, sizes, and multi‐stage heat dissipation processes realistically, so it can more precisely calculate the dynamic hot‐spot temperature. According to the simulated temperature curves at different operating conditions, the thermal constants and oil exponent are estimated using non‐linear regression, and the winding exponent is optimised using linear regression. A case study is conducted on an ONAN transformer. It shows the improved IEC model with optimised parameters can more accurately evaluate hot‐spot temperature, and the absolute error is decreased by 2.4 K (38.7%) compared with traditional thermal models.

Identification for Thermal Energy Optimization in the Process of Esterification Through the Evaluation of Combustion Reactions in Thermal Oil Heater

Identification for Thermal Energy Optimization in the Process of Esterification Through the Evaluation of Combustion Reactions in Thermal Oil Heater

An Antimicrobial, Environmental Protection, and High‐Efficiency Solar Steam Generator Based on Carbonized Sawdust

Solar‐powered desalination technology offers a promising solution to the global scarcity of freshwater resources. Recently, researchers have become interested in solar‐powered steam generators utilizing biomass materials. Herein, wood waste (sawdust) is recycled and subjected to high‐temperature treatment to obtain carbonized sawdust (CSd), which is sprayed onto the surface of a sponge to assemble a sponge‐based light absorber. The impact of sawdust carbonization temperature on water evaporation performance is examined, and it is found that a sponge‐based light absorber with a sawdust carbonization temperature of 600 °C exhibits a photothermal conversion efficiency of 87.7% while maintaining low‐energy consumption. Incorporating metal Ag into the light absorber improves water evaporation performance (photothermal conversion efficiency of 92.3%) and provides antibacterial properties. This photothermal evaporator maintains 89% photothermal conversion efficiency after 24 h of operation under 1 sun irradiation in 3.5 wt% NaCl solution. The antibacterial, efficient solar steam generator is expected for practical seawater desalination.

Thermodynamic and techno-economic analysis of a direct thermal oil vaporization solar power system

A unique direct thermal oil vaporization solar power system employing cascade organic-steam Rankine cycle is proposed. The oil is a mixture of biphenyl and diphenyl oxide, and it is used for heat transfer, storage and power cycle fluid in the novel system. Stable electricity output and prolonged storage capacity can be facilitated. In the rated mode, the oil is vaporized at 390 °C in the collectors and drives a top turbine. The exhaust heat is used for preheating and evaporating water of the bottom cycle. Meanwhile, the hot oil in a high-temperature tank (HTT) superheats and reheats the generated steam. When the irradiation is insufficient, the heat released by the oil from the HTT to a low-temperature tank drives the bottom cycle. Fundamentals, thermodynamic performance and techno-economic feasibility are elaborated. The results indicate that, compared with the mainstream dual-tank solar power systems, the proposed system has a higher thermal efficiency with a lower water evaporation temperature (42.90% at 260 °C vs. 38.06% at 310 °C) and a larger temperature drop between the two tanks (121 °C vs. 100 °C). The equivalent payback time with respect to the top oil cycle is less than 3 years.

Heat transfer characteristics of the innovative spray-type packed bed thermal energy storage: An experimental study

The shift to clean energy and the promotion of renewable energy sources are the dominant trends in the sustainable development of global energy employment. Thermal energy storage (TES) technology can help reduce the mismatch between thermal energy supply and demand by smoothing out peak demand periods. The spray-type packed bed thermal energy storage is an innovative heat storage technology that reduces the use of liquid heat transfer fluid (HTF) by introducing a spray device. However, the mechanism of flow and heat transfer inside the spray-type packed bed thermal energy storage is not yet clear. Therefore, in this study, a 10 kW/10 kWh spray-type packed bed TES test rig was established using aluminum spheres as storage media and thermal oil as HTF, and the heat transfer performance was studied experimentally. The results indicate that higher charging temperatures and flow rates lead to a higher liquid-to-particle heat transfer coefficient. An empirical correlation for heat transfer in spray-type packed bed TES was developed. With substantial reduction in HTF usage, the heat transfer Nusselt number of spray-type packed bed can basically approach that of a fully-filled packed bed.

Thermal Storage: From Low‐to‐High‐Temperature Systems

Different technologies of cold and heat storages are developed at Fraunhofer ISE. Herein, an overview of ongoing research for sensible and latent thermal energy storages is provided. Phase change emulsions are developed supported by molecular dynamic simulations. A narrow temperature range of the phase change is crucial for the applicability. By the simulations, a nucleation additive is identified that reduces supercooling by up to 9 K. The long‐term stability of phase change material is investigated by degradation experiments. Thermal cycling and ageing of materials at elevated temperature are applied. The change of melting enthalpy and characteristic temperatures are evaluated. Among erythritol, adipic acid, and myristic acid, the smallest degradation is observed for the latter. For sensible storage, the reduction of thermal oil by low‐cost filler materials and their compatibility is investigated at elevated temperature. It can be concluded that the materials are compatible up to 320 °C. At the component level, different macroencapsulations and immersed heat exchangers are tested for phase change materials. The investigated configurations achieve similar values of thermal power during (dis‐)charge. Compared to water as storage medium, the capacity increases by a factor of 2.2 and 4.1 for the macroencapsulation and the immersed heat exchanger, respectively.

Thermo-catalytic pyrolysis of Azadirachta indica seeds over CaO and CuO: Pyrolysis kinetics, impact of catalysts on yield, fuel properties and its chemical compositions

Pyrolysis oil and distribution is still in the incipient stages, though it is a potential source of energy and valueable chemicals. The current work focused on the kinetics study and thermo-catalytic pyrolysis of Azadirachta indica seeds (AZI) over CaO and CuO. The kinetic behaviour of AZI is studied in a TGA under an inert atmosphere at dynamic heating rates (10, 20 and 30 °C min−1) using Starink method (ST) and Vyazovkin model (VM). Further, AZI were pyrolyzed in a semi-batch tubular reactor at 500 °C, 50 °C min−1 heating rate and 100 mL min−1 nitrogen flow rate at 20 wt% catalyst loading. The biomass and pyrolysis liquid were characterised via proximate analysis, elemental analysis, thermal stability, FTIR, viscosity, density, acidity, moisture content, GC-MS etc. Kinetic analysis of AZIs confirmed that biomass decomposition takes place in a multifaceted route, and the activation energy is associated with conversion and temperature. Thermal pyrolysis exhibited 39.53 wt% liquid yields; however, introducing 20 wt% catalyst has improved the yield to 46.53 wt% and 45.36 wt% for CaO and CuO, respectively. The findings of the thermal and catalytic pyrolytic oil demonstrated that the addition of catalysts significantly enhanced the properties of pyrolytic oil by lowering viscosity and oxygen content while raising heating value and acidity. Finally, GC-MS results displayed that the use of catalysts resulted in a considerable decline in the proportion of oxygenated compounds, acids, and phenols and an increase in the proportion of hydrocarbons, aldehydes and alcohols.

Study of main factors influencing unsteady-state temperature drop in oil tank storage under dynamic thermal environment coupling

With the increasing oil demand, the construction of oil energy reserves in China needs to be further strengthened. However, given that there has been no research on the main influencing factors of crude oil temperature drop in storage tanks under actual dynamically changing environments, this paper considers the influence of dynamic thermal environment and internal crude oil physical properties on the fluctuating changes in crude oil temperature. A theoretical model of the unsteady-state temperature drop heat transfer process is developed from a three-dimensional perspective. According to the temperature drop variation law of crude oil storage tank under the coupling effect of various heat transfer modes such as external forced convection, thermal radiation, and internal natural convection, the external dynamic thermal environment influence zone, the internal crude oil physical property influence zone, and the intermediate transition zone of the tank are proposed. And the multiple non-linear regression method is used to quantitatively characterize the influence of external ambient temperature, solar radiation, wind speed, internal crude oil density, viscosity, and specific heat capacity on the temperature drop of crude oil in each influencing zone. The results of this paper not only quantitatively explain the main influencing factors of the oil temperature drop in the top, wall, and bottom regions of the tank, but also provide a theoretical reference for oil security reserves under a dynamic thermal environment.

Fabrication of cellulose-based aerogel from banana stem for thermal insulation and water treatment

Herein banana stem was used as a source of cellulose to fabricate a novel material that can be used in thermal insulation and water treatment. Characterization of the fabricated aerogels was carried out. The results expressed morphology, appearances, and thermal stability of the aerogels. The cellulose-based aerogels expressed low density (about 0.043 g/cm3), super high porosity (up to 98.11%), high compressive Young’s Modulus value (up to 365.5 kPa), ultra-low thermal conductivity (0.0362 to 0.0367 W/mK), and the oil adsorption capability up to 17.42 g/g. By applying a simple and green procedure, our banana stem aerogel could be used for further applications in material industry as those for thermal insulation and oil adsorption.

DENSITY OF HYDROCARBONS AND DEEP HEAT FLOW OF THE TERRITORY (SOUTHEAST OF WESTERN SIBERIA)

Link for citation: Krutenko D.S., Isaev V.I., Isaev S.G. Density of hydrocarbons and deep heat flow of the territory (southeast of Western Siberia). Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2023, vol. 334, no. 7, рр. 148-163. In Rus. The relevance. According to the ruling theory for organic origin of petroleum, geothermal regime is considered to be the main factor, which is responsible for realization of potential for oil generation. Therefore, it is not irrelevant to develop geothermics as a method of exploration geophysics for forecasting and evaluating oil and gas potential. Forecast tasks are reduced to detection local geothermal anomalies and establishing its relation to hydrocarbon deposits. This method may make a good showing while supplementary exploration in the territories with well-developed infrastructure and a large amount of wells as it is based on modelling and analysing of available data and does not propose additional field works. The main aim: establishing qualitative and quantitative relations between deep heat flow and oil and gas potential, also between gradient zones of heat flow and localization of hydrocarbon fields in the west of Tomsk Region. Objects: thermal field and oil and gas potential in the west of Tomsk Region. Subjects. The thermal field is described with such parameters as deep heat flow density and horizontal gradient of heat flow. Hydrocarbon fields are divided depending on fluid type into oil, oil-gas-condensate and gas-condensate. Methods. The deep heat flow was determined through paleotemperature modelling. The grid with cells of 20×20 km was set on study territory in increments of 10 km. Heat flow values were determined in the centers of each cell using Kriging interpolation method. The absolute horizontal gradient of heat flow was calculated on the same grid using five spot formula. Quantitative parameter of oil and gas potential – hydrocarbon density – was determined on the same grid. Quantitative relations were investigated by correlation and regression analysis. Relationships of heat flow density and horizontal gradient of heat flow with localization of hydrocarbon fields of different fluid type were detected by one-way ANOVA test. Results. The main results of this study are established distribution patterns for deposits of different fluid type in thermal field. Correlation analysis showed highly significant correlation coefficients. The conclusion. Oil and oil-gas-condensate fields tend to the average heat flow values (52 mW/m2), while gas-condensate are associated with high heat flow values (57 mW/m2). The value of the absolute horizontal gradient of heat flow increases in row oil fields – oil-gas-condensate fields – gas-condensate fields. The difference between average values of gradient for all of field types is statistically significant. Therefore, we indicate appearance of geothermal quantitative criterion for forecasting fluid type of deposits in areas of high potential for hydrocarbons. Quantitative relation of high significance (r=0,53) between heat flow density and hydrocarbon density is established for high heat flow values (&gt;56 mW/m2). Weak correlation (r=0,3) was indicated between horizontal gradient of heat flow and hydrocarbon density.

Accelerating flow for engine oil base fluid with graphene oxide and molybdenum disulfide nanoparticles: modified fractional simulations

Thermal assessment of hybrid nanofluid presents novel applications in enhancing heat transfer devices, solar energy production, extrusion systems, chemical processes, nuclear reactors, cooling processes, etc. Owing to such conveying applications of hybrid nanomaterials, the aim of current research is to justify the impressive thermal mechanism engine oil with the utilization of hybrid nanoparticles. The molybdenum disulfide and graphene oxide nanoparticles are used to reflect the improvement in engine oil thermal performances. The motivations for considering such hybrid nanofluid model are to improve the thermal aspect of engine oil which play a key contribution in the vehicle systems and automobile industry. The problem is further improved with mixed convection and Newtonian heating applications. The oscillating surface is used to endorse the flow. The fractional simulations with the implementation of Caputo–Fabrizio (CF) technique are performed. In contrast to traditional attempts, the modern -Laplace transform is used to compute the integration task.

The thermodynamic potential of high-temperature transcritical heat pump cycles for industrial processes with large temperature glides

Industrial heat pumps up to 200 °C are an emerging technology with the potential to reshape the industrial heating supply. For large heat sink temperature glides, transcritical cycles are able to increase the power-to-heat efficiency. Its potential is however yet to be unlocked. To examine this potential, a thermodynamic optimization model is proposed. The model includes robust cycle optimization, is able to screen a large set of working fluids, and includes proper post-processing. This model is applied to three highly relevant industrial cases, namely thermal oil heating, superheated steam drying and spray drying. The heat sink temperature glides for the respective case studies are 60 K, 81 K and 105 K. The results show that a temperature glide larger than 60 K is desired to achieve a better coefficient of performance (COP) with transcritical cycles compared to the classical subcritical cycles. Moreover, potential working fluids were identified for these high operational temperatures. For the case study with a heat sink temperature glide of 81 K, transcritical cycles allowed for a COP increase of 4.6%, whereas this increased to 7.3% for a heat sink temperature glide of 105 K. Furthermore, transcritical cycles introduce a much larger volumetric heating capacity, a lower compressor discharge temperature and a substantially lower pressure ratio. In addition, the best performing working fluids for subcritical cycles are highly flammable, which is only the case for some transcritical working fluids. Therefore, these cycles can be beneficial for temperature glides below 60 K. The compressor for transcritical cycles should however be able to cope with pressures up to 60 bar. If these compressors are available, transcritical cycles are shown to be superior compared to classical subcritical cycles.