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Carbon emissions and excessive power usage are addressed by applying thermoelectric cooling, which benefits from its ability to be portable, economical, and reliable. However, a conventional thermoelectric air conditioner's coefficient of performance (COP) is much less due to the sustained heat generated on the thermoelectric module's hot side. This work presents a novel idea of utilizing a nanofluid cooled radiator as an external cooling jacket around the thermoelectric module's hot side to enhance the heat transfer rate of thermoelectric air conditioners. In this research, the performance of a newly designed thermoelectric air conditioner (TEAC) powered by photovoltaic systems (PV) installed in a residential building is analyzed using nanofluid as a coolant. Furthermore, by supplying different input currents (2-6A), the cooling characteristics and performance of the newly designed nanofluid assisted thermoelectric air conditioner (NTEAC) system were experimentally studied in a test room of 25.6 m3 volume in Malaysia's tropical climate. The system's best performance was at 6A, with a maximum temperature drop of 4.9 °C, a cooling capacity of 571 W, and a coefficient of performance of 1.27. In addition, the NTEAC system showed an energy saving of 67% and CO2 emission mitigation of 76% when compared with a conventional split air conditioner. Thus, an alternative to the traditional air conditioning system was developed from this research, which is Freon free. This system is expected to consume less energy and emit less CO2 for the tropical climatic conditions.

Conventional surfactants such as CTAB (cetrimonium bromide), SDS (sodium dodecyl sulphate), SDBS (sodium dodecyl sulphonate) are combined with nanofluids to improve the stability and thermal conductivity of nanofluids. These nanofluids are mainly used for heat transfer applications where heating and cooling are usual courses of action which result in surfactants producing foams and polluting the heat transfer media, affecting the total system performance. Besides, the common surfactant molecules that augment the thermal resistance between the nanoparticles and base fluid also affect the thermophysical properties of the nanofluid. In this paper, [Bmim][Cl] (1-butyl-3-methylimidazolium chloride), a high purity ionic liquid (IL) with higher thermal stability was used to provide a comparative study on the stability and thermal properties with that of the conventional surfactants (CTAB, SDS, SDBS) on multiwalled carbon nanotubes (MWCNT)/propylene glycol (PG) nanofluid. The transient hot-wire based KD2-Pro and zeta potential results demonstrated that the inclusion of ionic liquid improved the thermal conductivity and stability of the formulated nanofluid. However, much like the conventional surfactants, the strong electrostatic repulsive force created by the ionic liquid was found to decrease when the temperature is increased. The outcome demonstrated the most extreme thermal conductivity upgrade of 33.7% at 303 K and maximum dispersion stability of more than one month without any aggregation for the nanofluid containing ionic liquid.

Increasing population combined with pollution of water bodies makes human being on this earth fully dependent on purified or desalinated water Keeping in mind the end goal to take care of the demand for consumable water, desalination systems of different kind have been proposed by many industrial establishments and research groups. Among the known water purification system Humidification Dehumidification (HDH) has become popular due to its simple operation, economic viability, absence of skilled labor and dependence on green and low grade energy to power the system. The theoretical analysis has been carried out using a simulation code in ‘C’ language to study the performance and quantity of output at various operating conditions. Results demonstrate that with increment in the mass flow rate of water and air, the effect of productivity on desalinated water increases and decreases respectively. In addition, the freshwater output increases with decrease in the heat input which is favorable for the enhancement of desalination efficiency.

The well-known fact of metallurgy is that the lifetime of a metal structure depends on the material's corrosion rate. Therefore, applying an appropriate prediction of corrosion process for the manufactured metals or alloys trigger an extended life of the product. At present, the current prediction models for additive manufactured alloys are either complicated or built on a restricted basis towards corrosion depletion. This paper presents a novel approach to estimate the corrosion rate and corrosion potential prediction by considering significant major parameters such as solution time, aging time, aging temperature, and corrosion test time. The Laser Engineered Net Shaping (LENS), which is an additive manufacturing process used in the manufacturing of health care equipment, was investigated in the present research. All the accumulated information used to manufacture the LENS-based Cobalt-Chromium-Molybdenum (CoCrMo) alloy was considered from previous literature. They enabled to create a robust Bayesian Regularization (BR)-based Artificial Neural Network (ANN) in order to predict with accuracy the material best corrosion properties. The achieved data were validated by investigating its experimental behavior. It was found a very good agreement between the predicted values generated with the BRANN model and experimental values. The robustness of the proposed approach allows to implement the manufactured materials successfully in the biomedical implants.

Fuel and electricity consumption for buildings is a crucial aspect of the tropical countries’ policy for limiting national electricity use and thereby reducing atmospheric carbon emissions. Currently, the energy demand for space conditioning is significantly higher, dominated by vapor compression air conditioning systems that contribute 30% of the global electricity consumption in tropical zones. Application of thermoelectric cooling modules can be regarded as one of the favorable options to solve the issue of high electricity consumption and CO2 emissions. This chapter reviews the growing importance of thermoelectric air conditioning systems in buildings. Moreover, thermoelectric coolers that work on the principle of Peltier effect possess certain advantages such as compact size, no moving parts, easy cooling rate control, long life span, and no liquids or gases. In this study, the present scenario of energy supply, energy demand and energy consumption in different sectors of tropical countries is discussed in more detail. Furthermore, the working principles of conventional air conditioning systems are presented and compared with thermoelectric air conditioning principle. This chapter also includes the recent investigations on the advancements and developments in thermoelectric air conditioning for buildings. Finally, this study tends to understand how efficiently thermoelectric cooling systems generate cooling, and its potential to replace traditional air conditioning systems.

The suspension of nanoparticles with common heat transfer fluids like Ethylene glycol and water yields nanofluid exhibits superior thermal properties than their host fluids. Ionic liquids have the potential to demonstrate remarkable thermophysical properties (especially thermal conductivity) that ordinary nanofluids cannot achieve. On the other hand, the quantity and structure of nanoparticles porosity affects the nanofluid’s thermal conductivity considerably. Various investigations have revealed the improved thermophysical characteristicts of Multiwalled Carbon nanotubes (MWCNTs) nanofluids containing common solvents or base fluids. However, only limited studies are available on the impact of thermal conductivity in Ionic liquid-based nanofluids (Ionanofluids) owing to their high cost and viscosity. Ultrasonication technique is employed in preparing the three different Ionanofluids containing 0.5 Wt.% via the two-step method to achieve a greater stability and thermal conductivity without utilizing surfactants. Experimental investigations are performed to boost the thermal conductivity of MWCNT/Propylene glycol nanofluid using 1,3-dimethyl imidazolium dimethyl phosphate [Mmim][DMP], 1-ethyl-3-methyl imidazolium octyl sulfate [Emim][OSO4] and 1-ethyl-3-methyl imidazolium diethyl phosphate [Emim][DEP] at a temperature ranging from 295 K to 355 K. The acquired results illustrated that the thermal conductivity of MWCNT Ionanofluids incorporated with [Mmim][DMP], [Emim][OSO4] and [Emim][DEP] increased by 37.5%, 5% and 2% respectively. This unique class of Ionanofluids shows incredible capacity for use in high temperature applications as conventional heat transfer fluids.

Graphene, a single-layer hexagonal carbon atom lattice, has recently emerged as an intriguing framework for basic experiments of condensed matter physics, as well as an exciting candidate for potential usage of heat transfer systems. Moreover, graphene nanofluid has excellent anisotropic behavior regarding thermal conductivity. The most critical concerns for usage in diverse graphene nanofluid applications are inadequate dispersibility and insufficient stability in solvents. This study explores the stability and thermal conductivity of functionalized graphene wrapped with octadecylamine (ODA) surfactant and sonicated in ethylene glycol base fluid. In this study, graphene nanoparticles are functionalized with chemicals like nitric acid and sulphuric acid, and it is wrapped with ODA, and its thermal conductivity and dispersion behavior is evaluated. The results show that the maximum thermal conductivity was 0.43 W/m.K at 55 °C while the formulated nanofluid is stable for six days.

Heat dissipation of various electrical and electronic devices has been a significant concern in the current years of modernisation. Many researchers proved that a liquid-cooled microchannel heat sink (MCHS) is an effective way of removing high heat load. Due to ionic liquids� unique properties such as negligible volatility, non-flammability, high thermal stability, and ionic conductivity, this liquid is combined with nanofluids to synthesise a new class of potential fluids termed Ionanofluids (ionic liquid-based nanofluids). In this research, a numerical simulation of fluid flow and heat transfer characteristics of MWCNT (Multiwalled Carbon Nanotubes) based Ionanofluids as a coolant in a rectangular-shaped microchannel heat sink is analysed. The Two-step method is used for preparing the studied Ionanofluids consisting of 0.5 wt. of MWCNT nanoparticles ultra-sonicated with a mixture of propylene glycol and 1-Butyl-3-methylimidazolium chloride (BmimCl-ionic liquid) fluids. Copper micro channelled heat sink comprising 1 m channel height, 25 µm of channel diameter, and 0.7 m channel width is modelled and simulated with ANSYS-Fluent. The results showed that the heat transfer coefficient increases about 11.4% while the thermal resistance decreases about 15.18% by using the proposed ionanofluids with the concentration of 0.5 wt.% at Re=2000 compared with that of an MCHS with propylene glycol. Moreover, the pressure drop along the studied MCHS increased up to a maximum of 30 kPa for higher heat gradients. Ionanofluids decreased the thermal resistance and temperature difference between the heated surface of the MCHS and Ionanofluids inlet to a greater extent when validated with pure base fluid and previous studies. From the simulated results, a better cooling performance is observed with Ionanofluids compared to pure propylene glycol (PG) for the proposed microchannel heat sink. © The Authors 2020. Published by Penerbit UMP. This is an open access article under the CC BY license.

Multi-walled carbon nanotubes (MWCNTs) are a contemporary class of nanoparticles that have a prominent thermal, electrical and mechanical properties. There have been numerous studies on the enhancement of thermophysical properties of nanofluids. However, there is only limited research on thermal and stability analysis of MWCNT nanofluids with various kinds of solvents or base fluids, namely propylene glycol, ethanol, ethylene glycol, polyethylene glycol, methanol and water. This paper reports the enhancement of thermophysical properties and stability of MWCNTs with six different base fluids in the presence of sodium dodecyl benzene sulfonate surfactant with a mass concentration of 0.5 wt. Thermal and dispersion stabilities were determined using a thermogravimetric analyzer (TGA) and Zeta potential, along with a visual inspection method to evaluate the agglomeration or sedimentation of MWCNT nanoparticles over a period of one month. Ultraviolet-visible spectroscopy and Fourier transform infrared spectroscopy were utilized to identify the molecular components and light absorption of the formulated nanofluids at their maximum wavenumber (4500 cm-1) and wavelength (800 nm). In addition, thermophysical properties such as thermal conductivity, specific heat capacity, viscosity and density with a peak temperature of 200 C were also experimentally evaluated. The TGA results illustrated that MWCNT/ethylene glycol nanofluid achieved maximum thermal stability at 140 C and it revealed a maximum zeta potential value of -61.8 mV. Thus, ethylene glycol solution was found to be the best base liquid to homogenize with MWCNTs for acquiring an enhanced thermophysical property and a long-term stability. © 2020 IOP Publishing Ltd.

Shafts are rotating elements that are subjected to torsion and bending moments that cause failures at times leading to personal injury, capacity loss, or poor product quality if basic preventive design actions are not taken. Against this background, this paper describes the failure analysis and root cause of a broken SA564 grade stainless steel pump shaft used in a plant through visual inspection, metallography, X-ray diffraction, scanning electron microscope, chemical analysis, hardness, tensile and non-destructive tests. The results show that creep, fatigue initiation and propagation from defects in the material during the operation were the predominant factors of pump shaft failure. Moreover, the existence of voids, micro-cracks, sensitisation and creeps were also identified on the broken shaft. Overall, the studied broken shaft of the impeller failed due to fatigue, initiated at the fillet radius of the keyway due to the high cyclic stress loading.

Experimental data of thermal conductivity, thermal stability, specific heat capacity, viscosity, UV&ndash, vis (light transmittance) and FTIR (light absorption) of Multiwalled Carbon Nanotubes (MWCNTs) dispersed in glycols, alcohols and water with the addition of sodium dodecylbenzene sulfonate (SDBS) surfactant for 0.5 wt % concentration along a temperature range of 25 &deg, C to 200 &deg, C were verified using Artificial Neural Networks (ANNs). In this research, an ANN approach was proposed using experimental datasets to predict the relative thermophysical properties of the tested nanofluids in the available literature. Throughout the designed network, 65% and 25% of data points were comprehended in the training and testing set while the other 10% was utilized as a validation set. The parameters such as temperature, concentration, size and time were considered as inputs while the thermophysical properties were considered as outputs to develop ANN models of further predictions with unseen datasets. The results found to be satisfactory as the (coefficient of determination) R2 values are close to 1.0. The predicted results of the nanofluids&rsquo, thermophysical properties were then validated with experimental dataset values. The validation plots of all individual samples for all properties were graphically generated. A comparison study was conducted for the robustness of the proposed approach. This work may help to reduce the experimental time and cost in the future.

Researches on the improvement of heat transfer using nanofluids, ionanofluids, and nanofluid assisted devices have gained significant attention worldwide since the previous decade due to their remarkable properties. However, there are many difficulties in preparing a stable nanofluid and integrating it for practical applications to increase the dissipation of heat from any thermal systems. Even though there are some reviews on nanofluids and nanofluid assisted heat transfer devices separately, an attempt has been made to analyze the latest researches on nanofluids and ionanofluids that lead to an important discussion to enhance the thermal performance of a system. In this paper, we summarized the preparation, thermophysical and hydrothermal properties, mechanisms, factors responsible for obtaining stable and enhanced thermophysical properties furthermore and its benefits on integration with heat transfer applications. The present study compiles theoretical and experimental studies from researchers investigating on stable nanofluids and ionanofluids, incorporating their effects on heat transfer applications.

In this paper, the thermal stability and specific heat capacities of four imidazolium based ionic liquids namely 1-ethyl-3-methyl imidazolium octylsulfate, 1-ethyl-3-methylimidazolium diethyl phosphate, 1,3-dimethyl-imidazolium dimethyl phosphate and 1-butyl-3-methylimidazolium chloride have been experimentally analysed using Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). The thermal stability was assessed by conventional and high resolution modulated TGA with the temperature range of 0 to 700 °C. The specific heat capacity was measured by using DSC within the temperature interval of 0 to 200 °C. The factors influencing the thermal stability and heat capacity of ionic liquids were studied. The thermal analysis results indicate that 1-ethyl-3-methylimidazolium octylsulfate exhibited excellent thermal stability even at 440 °C while 1-ethyl-3-methylimidazolium diethyl phosphate obtained a maximum specific heat capacity of 4.52 J/g.K.

Predictions are reported for mixed convection using various types of nanofluids over forward-facing double steps in a duct. The continuity, momentum and energy equations are discretized and the simple algorithm is applied to link the pressure and flow fields inside the domain. Different types of nanoparticles Al2O3, CuO, SiO2 and ZnO, with different volume fractions in range of 1-4% are investigated to identify their effects on the heat transfer and fluid characteristics. Numerical investigations are conducted using finite volume method. The results indicate that SiO2 -water has the highest Nusselt number followed by Al2O3-water, CuO -water and ZnO-water. The Nusselt number increases as the volume fraction increases but decreases as the nanoparticles diameter increases.

Microstructural Analysis plays an important role in enhancing the mechanical properties of metals and composites. Usually Aluminium Silicon Carbide (Al6063/SiC) alloys are mixed with strontium, sodium and antimony for high durability even though they are toxic and costly. As an alternative calcium is used as an alloying element to improve the mechanical property of Al6063/Sic alloy. In this paper Al6063 is chosen as the matrix material while Sic is used as a reinforcement where calcium powder is added to modify the silicon phase of the composite. Finally, concentration of Silicon carbide is varied from 0 to 150 mg to produce four specimens of Al6063 alloy and it is subjected to microstructure analysis which showed the reduction of grain size and therefore improvement in the hardness from 52.9 HV to 58.4 HV and decrease in the wear loss from 3.97 to 3.27 percentage.