Here, the researchers carried out an experimental analysis of the effect of the TiO₂ nanosolution concentration on the heat transfer of the twin jet impingement on an aluminum plate surface. We used three different heat transfer enhancement processes. We considered the TiO₂ nanosolution coat, aluminum plate heat sink, and a twin jet impingement system. We also analyzed several other parameters like the nozzle spacing, nanosolution concentration, and the nozzle-to-plate distance and noted if these parameters could increase the heat transfer rate of the twin jet impingement system on a hot aluminum surface. The researchers prepared different nanosolutions, which consisted of varying concentrations, and coated them on the metal surface. Thereafter, we carried out an X-ray diffraction (XRD) and a Field Emission Scanning Electron Microscopy (FESEM) analysis for determining the structure and the homogeneous surface coating of the nanosolutions. This article also studied the different positions of the twin jets for determining the maximal Nusselt number (Nu). The researchers analyzed all the results and noted that the flow structure of the twin impingement jets at the interference zone was the major issue affecting the increase in the heat transfer rate. The combined influence of the spacing and nanoparticle concentration affected the flow structure, and therefore the heat transfer properties, wherein the Reynolds number (1% by volume concentration) maximally affected the Nusselt number. This improved the performance of various industrial and engineering applications. Hypothesis: Nusselt number was affected by the ratio of the nanoparticle size to the surface roughness. Heat transfer characteristics could be improved if the researchers selected an appropriate impingement system and selected the optimal levels of other factors. The surface coating with the TiO₂ nanosolution also positively affected the heat transfer rate.

This paper aims to investigate the utilization of octet truss lattice structures in gas turbine blades to achieve weight reduction and improvement in vibration characteristics, which are desired for turbine blades to improve the efficiency and load capacity of turbines. A solid blade model using NACA 23012 airfoil was designed as reference. Three lattice-based blades were designed and manufactured via additive manufacturing by replacing the internal volume of solid blades with octet truss unit cells of variable strut thickness. Experimental and numerical vibration analyses were performed on the blades to establish their suitability for potential use in turbine blades. A maximum weight reduction of 24.91% was achieved. The natural frequencies of lattice blades were higher than those of solid blades. A stress reduction up to 38.6% and deformation reduction of up to 21.5% compared with solid blades were also observed. Both experimental and numerical results showed good agreement with a maximum difference of 3.94% in natural frequencies. Therefore, apart from being lightweight, octet-truss-lattice-based blades have excellent vibration characteristics and low stress levels, thereby making these blades ideal for enhancing the efficiency and durability of gas turbines.

As the automotive industry progresses, electric vehicles (EV) grow with increasing demand throughout the world. Nickel-metal hydride (NiMH) battery and lithium-ion (Li-ion) are widely used in EV due to their advantages such as impressive energy density, good power density, and low self-discharge. However, the batteries must be operated within their optimum range for safety and good thermal management to enable a longer lifespan, lower costs, and improve safety for EV batteries. The need for a liquid cold plate (LCP) to be used in EV batteries is now highly reliable on the distribution of the required temperature rather than only standard cooling systems. The fins arrangement in the LCP would likewise impact the cooling efficiency of the EV battery. The main objective of this paper is to determine the heat transfer enhancement of liquid cold plate systems with the oblique fin and different types of liquid coolants. In the experimental test, two liquid types are used namely G13 ethylene glycol and distilled water in five steps, 10% ethylene glycol, 100% distilled water, 75% ethylene glycol + 25% distilled water, 50% ethylene glycol + 50% distilled water, and 25% ethylene glycol + 75% distilled water. Three different flow rates have been utilized which are 0.3, 0.5, and 0.7 GPM to maximize the productivity of flowing fluid and heat transferring with the gate door valve. The LCP encompasses the inline configuration of the oblique fin, which is able to enhance the heat transfer rate from the heater to the liquid cold plate. A GPM of 0.7 reached the least surface temperature for the battery in the three different flow levels. The LCP is capable of sustaining the ambient surface temperatures of the batteries just under the permissible 50 °C operating temperature, which indicates that the developed LCP with the oblique fin may perhaps become an effective option for the thermal control of EV batteries.

Impinging jets are considered to be a well-known technique that offers high local heat transfer rates. No correlation could be established in the literature between the significant parameters and the Nusselt number, and investigation of the interactions between the correlated factors has not been conducted before. An experimental analysis based on the twin impingement jet mechanism was achieved to study the heat transfer rate pertaining to the surface plate. In the current paper, four influential parameters were studied: the spacing between nozzles, velocity, concentration of Nano solution coating and nozzle-plate distance, which are considered to be effective parameters for the thermal conductivity and the heat transfer coefficient of TiO₂ nanoparticle, an X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) analysis were done, which highlighted the structure and showed that the nanosolution coated the surface homogenously. Moreover, a comparison was done for the experimental results with that of the predicted responses generated by the Design Expert software, Version 7 User’s Guide, USA. A response surface methodology (RSM) was employed to improve a mathematical model by accounting for a D-optimal design. In addition, the analysis of variance (ANOVA) was employed for testing the significance of the models. The maximum Nu of 91.47, where H = S = 1 cm; Reynolds number of 17,000, and TiO₂ nanoparticle concentration of 0.5% M. The highest improvement rate in Nusselt was about 26%, achieved with TiO₂ Nanoparticle, when S = 3 cm, H = 6 cm and TiO₂ nanoparticle = 0.5 M. Furthermore, based on the statistical analysis, the expected values were found to be in satisfactory agreement with that of the empirical data, which was conducted by accounting for the proposed models’ excellent predictability. Multivariate approaches are very useful for researchers, as well as for applications in industrial processes, as they lead to increased efficiency and reduced costs, so the presented results of this work could encourage the overall uses of multivariate methods in these fields. Hypotheses: A comparison was done for the predicted responses generated by the Design Expert software with the experimental results and then studied to verify the following hypotheses: ► Preparation of three concentrations of TiO₂ nanosolution was done and studied. ► The heat transfer rate could be increased by surface coating with TiO₂ nanoparticle. ► The heat transfer could be improved by the impingement jet technique with suitable adjustments.

This article presents a study which sought to enhance heat transfer by employing a twin jet impingement mechanism (TJIM) and investigating the impact of the distance between the nozzles and plate on the Nusselt number (Nu) and heat transfer coefficient. This investigation was additionally based on the measurements of the heat flux temperature micro foil sensor and IR thermal imaging. A computational study of the cooling heated plate, through simulating the electronic components by the TJIM, was investigated using the RNG k-ε turbulence model. The jet-plate position was changed at the different jet-to-plate distances S = 1, 6, and 11 cm, Reynolds number = 17,000. The main flow structure, the static pressure, local and average Nus and heat transfer coefficient, were also examined. The findings have yielded new information about TJIM, and represent a new contribution about the flow and heat transfer characteristics of TJIM, and means of improving the rate of heat transfer in the passive heat transfer technique. The results of the various positions of the TJIM determined that the first model is, in fact, the best model for the heat transfer coefficient and the highest Nu, when S = 1 cm and H = 1 cm. Furthermore, the irregular distribution of the local Nu and the local heat transfer coefficient (h) on the impinged surface are due to the increase or decrease in the turbulence of flow on the measured surface.

Considerable research has been conducted in the past decade and a half regarding the bio-lubricants potential to replace mineral-based lubricants as mainstream lubricants such as engine oil, hydraulic oil, compressor oil, and metalworking oil. This study studied several bio-lubricants (rapeseed oil, palm olein, and soybean oil) and a mineral-based lubricant, SAE40. The bio-lubricants have better physiochemical, tribological characteristics and environmental friendly nature, and are promising to replace mineral-based lubricants. In this study, a journal bearing test rig (JBTR) was developed in order to investigate the effect of journal speed on the temperature of oil film with time. Additionally, the load-carrying capacity of bio-oils was tested against the mineral-based lubricant SAE40 by adding a load on the journal. For all three speeds, i.e., 1000, 1500, and 2000 rpm, the bio-lubricants recorded minimum temperature. At 1000 rpm, rapeseed oil recorded a 9.2% lower temperature than SAE40. Similarly, at 2000 rpm, rapeseed oil recorded a minimum temperature that was 2.5% lower than SAE40; in comparison, at 1500 rpm, palm olein recorded a minimum temperature that was 1.8% less than SAE40. Overall, the results of this study revealed that bio-oils recorded a lower temperature rise than mineral oil. These results are very encouraging for further research in this area.