Traditional Working Fluids Research Articles

Performance Evaluation and Working Fluid Screening of Direct Vapor Generation for Solar ORC Using Low-Global Warming Potential (GWP) Working Fluids

Traditional working fluids used in direct vapor generation for solar organic Rankine cycle (DVG-ORC) systems have a high global warming potential (GWP), making it imperative to find environmentally friendly alternative working fluids for these systems. This paper evaluates the performance of the DVG-ORC system under different operating conditions. By comparing the results of traditional working fluids with those of low-GWP fluids, the feasibility of using low-GWP fluids as alternative working fluids is explored. Additionally, to screen the working fluids suitable for this system further, the system is optimized with net output power as the objective function. The results show that evaporation temperature has different impacts on system performance. R245ca and R1336mzz(Z) exhibit higher net output power at different evaporation temperatures, with R1336mzz(Z) only reducing it by 3.73–5.26% compared to R245ca. However, an increase in condensation temperature negatively affects system performance, leading to a decrease in net output power and various efficiencies. Net output power increases with an increase in mass flow rate, indicating that higher mass flow rates can enhance system performance. The optimization results show that the net output power of low-GWP working fluid R1336mzz(Z) decreases by only 3.44% compared to R245ca, which achieves the maximum net output power. Moreover, among low-GWP working fluids, R1336mzz(Z) demonstrates the highest ORC efficiency and system efficiency, making it the most suitable working fluid for the DVG-ORC system due to its environmental friendliness and safety.

Thermal analysis of solar energy based organic Rankine cycle cascaded with vapor compression refrigeration cycle

The air conditioning and refrigeration applications use a significant portion of the electrical energy. This research analyses a performance of refrigeration system, which comprises on different configurations of solar based organic Rankine cycle (ORC) and vapor compression refrigeration (VCR) cycles requiring low evaporation temperatures. In this research, the dry natural hydrocarbons such as n-Decane, n-Dodecane and Toluene have been chosen to serve as the working fluids in ORC. Whereas in VCR cycle natural hydrocarbons such as Ethane, Propane, isobutane, isopentane and isohexane have been used because traditional working fluids have a negative environmental impact due to high values of ozone depletion and global warming potential. The simulated results showed that the facility can be operated efficiently with the use solar thermal energy resources within the temperature range 90 to 315ºC and decreasing the need for conventional fossil fuel resources. It was also revealed that the highest efficiency was achieved by n-Dodecane in regenerative ORC, which is 35.34 % at the evaporation temperature of 315ºC and the highest overall coefficient of performance (COPoverall) in regenerative ORCCRS facility was achieved by n-Dodecane in ORC and isopentane in refrigeration cycle which is 1.017 while in case of Simple ORC–VCR facility the highest COPoverall was achieved by Toluene in ORC and isopentane in refrigeration cycle, which is 0.7174 at the evaporation temperature 315ºC.

Flow visualization experiments of argon injection in a molten salt natural circulation loop

Off-gas systems are implemented in molten salt reactor designs to control the release of gaseous fission products. Two-phase flow in molten salt must be studied to understand how the system will behave in comparison to traditional working fluids like water. Flow visualization experiments and particle image velocimetry measurements were performed for three argon bubble sizes injected into a co-current stream of molten salt in a natural circulation loop facility. Similar bubble sizes were injected in experiments with water to compare the bubble shape, trajectory, and wake flow behavior of the fluids. The bubble region of interest was used to calculate the equivalent diameter and terminal velocity. Results for water showed a wobbling bubble surface and less stable bubble trajectory due to lower surface tension and viscosity compared with molten salt. Particle image velocimetry results demonstrated the increased viscosity of salt dampens turbulent fluctuations for the smaller bubble size. For a cap bubble, turbulent fluctuations were larger and longer lasting than in results for the wake flow of an argon cap bubble in water.

Enhancing heat transfer in thermosyphons: The role of self-rewetting nanofluids, and filling ratios for improved performance

This study investigates the complex dynamics of heat transfer and phase change within a flat-shaped thermosyphon, examining various parameters and working fluids. The research explores the effects of different working fluids, filling ratios, and heat inputs on the system's thermal performance. This study employs an axisymmetric model, to enhance the accuracy of the solution compared to a 2D model while maintaining a low computational cost. To validate our numerical model, we conducted comprehensive comparisons with experimental data, including the axisymmetric model, and capturing the nanofluid effects. Remarkably, our simulations consistently align with the experimental findings, demonstrating a high degree of accuracy and reliability in our model.The findings show that self-rewetting nanofluids exhibit superior heat transfer capabilities and a reduced risk of dry-out compared to traditional working fluids. Notably, self-rewetting fluids and self-rewetting nanofluids exhibit a unique behavior, reversed surface tension trends with rising temperatures, which effectively prevents dry-out by attracting liquid to hot regions. Additionally, the enhanced thermal conductivity of nanofluids during boiling enhances their performance furthermore. Also, the research studies the impact of filling ratios on temperature profiles and heat transfer rates, emphasizing the importance of higher filling ratios in lowering bottom plate temperatures. These insights offer valuable guidance for optimizing thermosyphons in applications like electronic cooling.

Study on thermo-electrical performance of spray-cooled concentrating photovoltaic system using oleic acid modified nanofluid

In the utilization of solar photovoltaics, concentrated photovoltaic technology can effectively improve the efficiency of solar cells, but it is limited by the problems of contact thermal resistance and low thermal conductivity of working fluid in cooling technology. This article proposes a modified nanofluid spray cooling HCPV system, which not only overcomes the low heat carrying capacity of traditional working fluids, but also solves the problem of contact thermal resistance in the heat transfer process, further reducing the cell temperature to achieve higher heat transfer efficiency and electrical efficiency. At first, oleic acid (OA)-modified Al2O3 nanofluids (OA-Al2O3-H2O/C2H6O) were prepared. Otherwise, stability test methods and spray cooling heat transfer test benches were developed and built. Finally, the stability of nanofluids, the temperature field distribution and electrical efficiency of solar cells under high energy current density were tested, and the effects of flow rate and base-liquid ratio on system performance were analyzed. The results showed that: OA can keep Al2O3-H2O/C2H6O nanofluids more than 48 h, and the surface temperature is stable at 40 °C. Meanwhile, the electrical efficiency is always above 27 %, up to 29.37 % and 1.3 % higher than working fluid water.

Experimental and neural network prediction of the cyclic stability and light absorption characteristics of supercritical CO2 based CNTs nanofluids

Traditional working fluids face challenges including constrained heat transfer efficiency and inadequate thermal stability, which are detrimental to the thermal efficiency of energy conversion systems. To overcome these limitations and achieve a profound breakthrough in the field of energy conversion, it is imperative to develop innovative working fluids. Consequently, this study builds a nanofluid circulation flow experimental platform and prepares a supercritical carbon dioxide/hydroxylated multi-walled carbon nanotubes nanofluid. The study conducts a series of meaningful experimental tests and performance predictions, including stability analysis, deposition characterization research, light absorption potential investigation, and artificial neural network prediction. Remarkably, the artificial neural network model exhibits excellent learning capacity in training, validation, and testing, with root mean square error of only 9.069 W/m2, 8.9996 W/m2, and 13.0143 W/m2, respectively. Test results indicate that the nanofluid reaches a steady state after 4 min, with a fluctuation amplitude of only 2.13 %. Furthermore, the deposition density of the nanofluid on nickel sheet saturates after 4 h, confirming its considerable potential for promotion and application. The light absorption capacity and power decay rate of the nanofluid are enhanced by 606–881 W/m2 and 32.3–46.99 %, compared to other typical substances. The transmittance is reduced by 8.51–22.96 % compared to other nanofluids. The nanofluid proves to be an effective alternative to conventional working fluids, providing a practical reference solution for researchers aiming to improve working fluids in the field of energy conversion.

A Review of Nanofluid Boiling Heat Transfer and Its Applications in Heat Pipes

Nanofluid is a new type of heat transfer medium formed by adding metal or non-metal in liquid medium in a certain proportion and manner, which has many advantages over the traditional working fluid. Combining heat pipes with nanofluids and using nanofluids as the working material of heat pipes can reduce thermal resistance and effectively improve the heat transfer performance of heat pipes. This paper provides a relevant overview of heat pipes and nanofluids, and introduces the relevant classifications of heat pipes, the working principle and the relevant research on nanofluid-enhanced boiling heat transfer. It conducts a literature review on the application of nanofluids in heat pipes, and finally proposes possible future research directions.

Crystallization-free and low-cost deep eutectic solvents for absorption thermal battery utilizing ultra-low-grade energy

Absorption thermal batteries (ATBs) play a significant role in balancing the mismatch between ultra-low-grade renewable/waste energy supply and building energy demand. Working fluids are critical to the high performance and reliability of ATBs, but conventional salt-based mixtures suffer from crystallization risks, while the popular ionic liquid-based mixtures are quite expensive. Therefore, crystallization-free and low-cost deep eutectic solvents (DESs) are proposed to achieve reliable and affordable ATBs. The property estimation based on the NRTL model and the cycle model based on mass and energy conservation are established and verified with high accuracies, which are used to investigate the energy storage performance of five H2O/DESs and four NH3/DESs. A comprehensive comparison between the emerging DES-based and traditional working fluids from multifaceted viewpoints (efficiency, compactness, exergy, response rate, applicability, heat transfer, reliability, and economics) is conducted. For a basic ATB with inferior operating conditions (generation temperature < 72 °C, evaporation temperature < 1 °C, or absorption temperature > 40 °C), NH3/Glyceline yields the highest energy storage efficiency (ESE) and exergy efficiency (EXE), outperforming the traditional refrigerant/salts. A compression-assisted ATB is further adopted, enabling NH3/DESs to utilize ultra-low-grade heat as low as 40 °C. NH3/Glyceline yields the highest ESE of 0.752 and EXE of 0.599 at a generation temperature of 50 °C. It also exhibits a rapid response rate with the highest maximum vapor mass flow rate of 5.4 g/s and the shortest discharging time (73.22 min). NH3/Glyceline exhibits the widest applicability, with an applicable operating range ratio of 87.72%, much higher than that of H2O/LiBr (23.72%). The compression-assisted ATB using NH3/Glyceline is the most promising for large-scale applications owing to the lowest levelized cooling capacity cost of 0.239 $/kWh, which is 41.89% lower than that of H2O/LiBr and 96.58% lower than that of H2O/[EMIM][OAc].

How to rationally screen refrigerant/ionic liquids for thermal cooling: A multi-criteria approach based on machine learning

Absorption heat pumps (AHPs) for thermal cooling show great potential in utilizing renewable and waste heat towards carbon neutrality. AHPs using ionic liquids (ILs) as absorbents have attracted considerable attention for avoiding the shortcomings of traditional working fluids. To develop absorption technologies with high efficiency, compactness, and flexibility, a multi-criteria approach coupling the property models based on machine learning and UNIFAC methods, cycle models, and heat exchanger models is proposed to screen the optimum refrigerant/ILs. In terms of cycle performance, heat transfer performance, hydraulic resistance, and applicable range, the comprehensive performance of 214 novel refrigerant/ILs is estimated to identify suitable candidates. Six indicators are selected to compare the working pairs comprehensively: H2O/[OMIM][OAc] performs the best in terms of coefficient of performance (0.815), pumping power (0.071 W), and supply-side applicable operating ratio (76.8%), while NH3/[DBIM][Tf2N] yields the lowest saturation temperature drop (0.157 K) and the highest demand-side applicable operating ratio (64.9%). Within the studied IL-based working fluids, NH3/[DBIM][Tf2N] in the generator exhibits the highest heat transfer coefficient of 0.476 kW/(m2·K). Considering the trade-off between heat transfer performance and hydraulic resistance, satisfactory solution velocities are recommended for different working fluids with a saturation temperature drop limit of 2.2 °C. Based on the Pareto optimization, H2O/[OMIM][OAc] is highly recommended for industrial applications because of its crystallization-free nature, high COP, and compact system size. The proposed multi-criteria approach achieves large-scale screening of optimum ILs for highly efficient, compact, and flexible thermal cooling.

Review of enhanced heat and mass transfer by additives

The absorber is a key component of an absorption system, and its efficiency affects the performance of the overall system. This study summarizes and analyzes the development status of using additives to enhance heat and mass transfer. To address the problem of the low heat and mass transfer efficiency of absorbers, many researchers usually add additives to the circulation system of absorption chiller to enhance the heat and mass transfer processes. In this paper, the experimental studies on adding surfactants, nanoparticles, and salt compounds to traditional working fluid pairs are reviewed. Numerous research results show that the heat and mass transfer coefficients are enhanced after adding additives, and the cooling capacity is improved. Suggestions for enhancing heat and mass transfer in the absorption process are also presented in this paper.

Thermal and Hydraulic Performances of Carbon and Metallic Oxides-Based Nanomaterials

For companies, notably in the realms of energy and power supply, the essential requirement for highly efficient thermal transport solutions has become a serious concern. Current research highlighted the use of metallic oxides and carbon-based nanofluids as heat transfer fluids. This work examined two carbon forms (PEG@GNPs & PEG@TGr) and two types of metallic oxides (Al2O3 & SiO2) in a square heated pipe in the mass fraction of 0.1 wt.%. Laboratory conditions were as follows: 6401 ≤ Re ≤ 11,907 and wall heat flux = 11,205 W/m2. The effective thermal–physical and heat transfer properties were assessed for fully developed turbulent fluid flow at 20–60 °C. The thermal and hydraulic performances of nanofluids were rated in terms of pumping power, performance index (PI), and performance evaluation criteria (PEC). The heat transfer coefficients of the nanofluids improved the most: PEG@GNPs = 44.4%, PEG@TGr = 41.2%, Al2O3 = 22.5%, and SiO2 = 24%. Meanwhile, the highest augmentation in the Nu of the nanofluids was as follows: PEG@GNPs = 35%, PEG@TGr = 30.1%, Al2O3 = 20.6%, and SiO2 = 21.9%. The pressure loss and friction factor increased the highest, by 20.8–23.7% and 3.57–3.85%, respectively. In the end, the general performance of nanofluids has shown that they would be a good alternative to the traditional working fluids in heat transfer requests.

Nanotechnology Applications in Ground Heat Exchanger Pipes: A Review

The use of Ground Source Heat Pumps (GSHPs) has grown exponentially around the world over recent decades. The GSHP represents an alternative device to electric heating systems and oil boilers. Additionally, it requires a lower power consumption and less maintenance than combustion-based heating systems. Moreover, the CO2 emissions produced by a GSHP are lower than other systems based on burning oil, gas, or biomass. However, the main obstacle for the widespread use of GSHPs is the high cost of Ground Heat Exchanger (GHE) installation, a technology that exhibits low thermodynamic efficiencies. Over the past decade, some studies have been conducted to improve heat transfer in GHE pipes using traditional working fluids, creating new pipe materials or designing new heat exchanger configurations. The main contribution of this paper is a summarization of the outcomes of theoretical, numerical and experimental studies to improve heat transfer in GHEs using nanotechnology. Additionally, the development of new fluids (nanofluids) and new materials (nanoparticles and nanocomposites) applied to heat exchanger pipes and the designs and configurations of GHEs are highlighted. As a result, the present review provides a perspective for future research regarding the use of nanotechnology to reduce the costs involved in GHE for GSHP improvement.

Experimental study on the influence of bionic channel structure and nanofluids on power generation characteristics of waste heat utilisation equipment

• Snake-shaped bionic surface is applied to waste heat utilization equipment. • Influence of bionic structures on power generation characteristics is studied. • Thermoelectric conversion efficiency is studied. • Nanofluids increase temperature of the hot end by 7.19% at the maximum. To recover waste heat resources and improve the utilisation rate of waste heat, a cogeneration system based on bionics was designed. To ma x imise the utilisation rate of waste heat, the effects of different bionic channel structures (angular frequency ω = 20, 25, and 30 rad/s; amplitude A = 1, 2, and 3 mm; and phase shift α = 0°, 90°, and 180°) on the power generation characteristics were studied experimentally. The innovation of this study lies in designing bionic structures with different shapes and replacing traditional working fluids with nanofluids. The experimental results showed that, when the working medium was a CuO–H 2 O nanofluid, the temperature at the hot end of the thermoelectric plate increased by 7.19%. For different bionic structures, the thermoelectric conversion efficiency of waste heat utilisation equipment with ω = 30 rad/s, A = 3 mm, and α = 180° was the highest, being 15.29%, 18.79%, and 6.97% higher than those with ω = 20 rad/s, A = 1 mm, and α = 0°, respectively. The results of this study can provide guidance for the design and operation of the power generation characteristics of waste heat utilisation equipment.

Characterization of ZnO/nanofluid for improving heat transfer in thermal systems

Nanofluids are currently regarded a new growing area of research with numerous advantages over conventional heat transport fluids in heat transfer applications. Because, nanofluids possess a better thermo-physical characteristics. Hence, they can perform better when compared to traditional working fluids. The thermo-physical characteristics of zinc oxide nanoparticles disbanded water (ZnO/water) nanofluid was evaluated in this study by altering the volume proportions of nano-ZnO particles and temperature experimentally. The volume proportion of ZnO/water nanofluids was adjusted from 0.01 to 0.2 in four different (0.01, 0.05, 0.1 and 0.2) fractions. Using a field emission scanning electron microscope, the surface properties of ZnO nanoparticles were investigated. The results evidenced that the absolute viscosity, thermal conductivity, and density of the water was augmented by 1.43%, 37.0%, and 1.57%, respectively through the diffusion of 0.2 vol% of nano-ZnO particles in water. In contrast, the specific heat of water was lessened by 2.7% with 0.2 vol% of nano-ZnO particles in water.

Thermal analysis of a novel single-effect absorption refrigeration system using water/ionic liquid as working fluids

Based on the demand of improving the cooling performance of traditional absorption refrigeration system, a novel single-effect refrigeration system with assisted compressors using water/ionic liquids as working fluids was comprehensively analyzed. In present work, four kind of ionic liquids:1-butyl-3-methylimidazolium dibutylphosphate [BMIM][DBP], 1-methyl-3-methylimidazolium dimethylphosphate[MMIM][DMP], 1-ethyl-3-methylimidazolium dimethylphosphate [EMIM] [DMP], and 1-ethyl-3-methylimidazolium acetate [EMIM][AC], which was studied as working fluid in absorption system at the first time, was modeled and simulated in both systems. Thermodynamic properties of new single-effect refrigeration system were numerically analyzed by non-random two-liquid models and the mass and energy conservation equations. The effects of compression ratio(pr) and temperature on the COP and exergetic efficiency (ECOP) were graphed and discussed. The simulating results showed the potential of ionic liquids to be used as substitute for traditional working fluids. Moreover, comparison results suggested the system with auxiliary compressors was better than the traditional system for its lower heat source temperature and higher cooling performance. It was better to increase the compression ratio of the compressor located between the absorber and the evaporator than to increase the compression ratio of the compressor located between the generator and the condenser.

Experimental Investigation of a Loop Heat Pipe With R245fa and R1234ze(E) as Working Fluids

Abstract Two kinds of new refrigerant R1234ze(E) and R245fa were discussed as substitutes or supplements to traditional working fluids of loop heat pipes (LHPs) based on their favorable thermophysical properties and characteristics such as being safe and environmentally friendly. Thermal characteristics of a loop heat pipe with sintering copper wick at different charging ratios were experimentally investigated under variable heat loads. The results showed that the optimal charging ratio in the loop heat pipe range from 65% to 70%, and at this charging level, the R1234ze(E) system had better start-up response, while the R245fa system presented a stronger heat transfer capacity. The characteristic temperature of R1234ze(E) system was below 35 °C, and the corresponding thermal resistance was 0.08 K/W–1.62 K/W under heat loads ranging from 5 W to 40 W. The thermal resistance of the R245fa system was 0.18 K/W–0.91 K/W under heat loads of 10 W–60 W, and the operating temperature was below 60 °C. The loop heat pipes charged with the proposed new refrigerants exhibit superb performance in room temperature applications, making them beneficial for enhancing the performance of electronics and could provide a distinctive choice for the cooling of small-sized electronics especially.

A novel modified LiCl solution for three-phase absorption thermal energy storage and its thermal and physical properties

• A novel LiCl solution for three-phase absorption thermal energy storage is proposed. • The energy storage density of the solution is enhanced by adding two types of additives. • The LiCl crystal slurry overcomes the fluidity problem caused by crystallization. • Thermal and physical properties of the modified solution are measured by experiments. Absorption thermal energy storage (TES) is gaining increasing attention due to its large energy storage density (ESD), mobility and long-term thermal storage capability. Expanding the working concentration difference of a solution can significantly enhance its ESD; however, this may result in crystallization, influencing fluidity and blocking flow channels in a TES device. Furthermore, bulky crystals are difficult to dissolve during energy discharge. In this paper, a novel modified LiCl solution is proposed for three-phase absorption TES, which allows the growth of fine crystals and the formation of well suspended slurry. For the first time, two types of additives with competing mechanism are introduced into the solution: ethylene glycol as a crystallization inhibitor and SiO 2 nanoparticles (SNPs) as a nucleating agent. Compared with traditional working fluids, the proposed solution has a larger ESD and good fluidity. The expanded concentration difference is determined by experiments on solubility and suspension. The optimal mass ratio of the LiCl solution, ethylene glycol and SiO 2 nanoparticles are obtained considering both ESD and fluidity. Heat and cold storage density using this novel LiCl crystal slurry can be enhanced by 24.8% and 156.0% respectively. Measurements on thermal and physical properties including vapor pressure, density and viscosity are also carried out.

Experimental study on the influence of bionic channel structure on waste heat utilization equipment

AbstractIn this paper, in order to improve the efficiency of waste heat utilization, based on the movement type and shape of the snake, snake bionic surfaces with different structures were designed, and CuO–H2O nanofluids were used instead of traditional working fluids, and they were coupled together and applied to waste heat utilization equipment. The main work is to experimentally study the effects of nanofluids mass fraction (w = 0.1 wt%, 0.3 wt%, 0.5 wt%), amplitude of bionic channel structure (A = 1 mm, A = 2 mm, A = 3 mm), angular frequency of bionic channel structure (ω = 20 rad/s, ω = 25 rad/s, ω = 30 rad/s), phase shift of bionic channel structure (α = 0°, 90°, 180°), and Reynolds number (Re = 1,300–1800) on the flow and heat transfer characteristics of working fluid. It was found that the heat transfer capacity of nanofluids increases with nanofluids mass fraction, angular frequency, amplitude and phase shift. Finally, the comprehensive performance of the whole experimental system was studied, and it was found that the greater the angular frequency, amplitude and phase shift, the better the comprehensive performance of the heat exchanger.

Advanced Loop Thermosiphon With Check Valve (ALT/CV): Thermal Performance and Behavior

Nanofluids (NFs) are an attractive alternative to traditional working fluids for thermosiphons, but the solid nanoparticles (NPs) within the NF can agglomerate and reduce the thermal performance. This study focused on clarifying the effect of a NF with surfactants on the heat transfer characteristics of an advanced loop thermosiphon with a check valve (ALT/CV). In an experiment, the ALT/CV was filled with different working fluids at filling ratios of 30%, 50%, and 80% with respect to the evaporator volume. Heat was supplied at 20%, 40%, 60%, 80%, and 100% of the heater output (2000 W). Five working fluids were considered: deionized (DI) water, a DI water-based NF with 0.5 wt% silver NPs, and the same NF containing 0.5, 1, and 1.5 wt% oleic acid (OA) and potassium oleate (OAK+) as surfactants. The results showed that the ALT/CV provided a better heat transfer performance than a normal thermosiphon. The maximum heat transfer rate was achieved with the NF containing 0.5 wt% silver NPs and 1 wt% OAK+. The NF containing OAK+ demonstrated a heat transfer rate approximately 80% higher than that of the DI water

Convective heat transfer characteristics of nanofluids including the magnetic effect on heat transfer enhancement - a review

• Experimental and numerical investigations on the convective heat transfer of various nanofluids are summarized and discussed. • Convective heat transfer can be improved when small-sized nanoparticles was used. • Magnetic field in magnetic nanoparticles improves the convective heat transfer performance. The scope of this review enlightens the experimental and numerical investigations conducted on the convective heat transfer of various nanofluids, particularly hybrid nanofluids. Essential studies on the improvement of the convective heat transfer using suspensions of nanoparticles in traditional working fluids have recently appeared in the literature. Optimized heat and mass transfer of nanofluid are significantly affected by inherent nanofluid characteristics, synthesizing method for the nanofluid, the effect of magnetic force, concentration and size of nanoparticles, and Re (Reynolds number). Besides, a critical factor regarding the material properties, thermal properties, and performance of the magnetic nanofluids is highly sensitive to the small variation in the magnetic force and magnetic field gradient. Several studies have concluded that the magnetic field in magnetic nanoparticles improves the convective heat transfer performance of a nanofluid by approximately 13%–75%. Furthermore, some applications of a hybrid nanofluid in thermal systems have also been introduced.