Thermal contact conductance is an important concern in the heat transfer applications such as electronic packaging, engine cooling, nuclear cooling, and thermal control. The characterization of thermal contact conductance between the two solid plates is an important parameter in the designing of heat sinks in various industrial applications, where suitably different thermally conducting interface materials are employed. In the present investigation, glycerin and a commercially available thermal paste are used with and without the nanoparticles in the different particle concentrations. The effects of heat fluxes and interface materials on thermal conductance and heat transfer are estimated, experimentally. A reduction in the resistance to heat transfer at the interface of solid surfaces subjected to constant pressure is found for the higher concentration of nanoparticles. The effects of all the materials and temperature differences are duly reported and discussed.

Heat transfer characteristic of nanofluid has fascinated numerous researchers. Several parameters affecting it are being investigated. In this study, the thermal conductivity of low concentrated magnetite nanofluid under magnetic field is determined experimentally. The nanofluid is prepared using two-step method and its thermal conductivity is measured at different temperature (10°C–70°C), particle concentration (0.01

The use of nanoparticles in the thermal systems to enhance the heat transfer characteristics of working fluid is studied in the literature and found an efficient approach in the forced flow, while in the natural flows, the stability of nanoparticles affects the performance of thermal systems. A similar forced flow is also maintained in the refrigeration systems, where the nanoparticles are used to disperse in the refrigerant and/or lubricant. The performance of nano-refrigerant or nano-lubricant depends on the thermophysical properties, as well as the heat transfer characteristic and pumping power. On similar parameters, a review is presented in the presented study with the correlations used to calculate the thermal conductivity, viscosity, heat transfer coefficient, and Nusselt number.

The nanofluids are the promising smart fluids having advanced thermophysical properties. The earlier chapters have talked about various fascinating facts about the nanofluids. One of the important aspects of the nanofluids is the stability of the nanoparticles. The uniform and long-term suspension is the key and critical feature required in the nanofluids for the industrial applications of these advanced fluids. The chapter summarizes various stability evaluation methods and techniques to enhance the stability of nanofluids. There are number of methods to investigate the stability of the nanofluids. The various types of surfactants and additives are used by the researchers to enhance the stability of the nanofluids. The key factor of using additives is that it is influencing the thermophysical properties and chemical properties of such fluids. The mechanics behind the stability of nanofluids are also discussed in the article.

This book presents the latest information and discussion on the preparation and advanced characterization of nanofluids

Agriculture is the main occupation of Indian population. Although 70% of the population is employed in agriculture, its share in the GDP is only about 20.5%. This low contribution to GDP from agricultural sector is mainly due to use of traditional outdated technology. Hence, there is a need for improvement in agricultural sector. For improvement in each and every steps in the crop production, new devices are required. Application of robotics in agriculture is not new. In this project, an attempt has been made to design and analyze a robot (Agri-Rover) which will provide complete solution for multifarious activities associated with agriculture. The operation of seed sowing is carried out by the system using a particular mechanism which in turn is controlled by an ARDUINO controller and the motion of the robot is controlled by Internet of things (IOT). The advantage of a small seeding machine is that it can be maneuvered in a small area.

The natural convection is ubiquitous in nature, and technology and abundant of experimental and numerical studies have been conducted to investigate the fascinating characteristics of the phenomena. The natural convection has the wide range of application in almost every field of technologies such as solar energy, electronics cooling and nuclear energy. The enhancement of heat transfer by the natural convection is a challenging task, and nanofluids are considered to have a potential for the enhancement in heat transfer. The main aim of the chapter is to comprehensively discuss the mechanism about natural convection in nanofluids and explore the various characteristics related to nanofluid natural convective heat transfer. As discussed in previous chapters, the thermal conductivity of the nanofluid plays an important role in the heat transfer. The article has discussed the dependence of natural convection in nanofluids on the thermophysical properties. The various studies have systematically summarized to discuss the effects of various parameters on the heat transfer and to optimize these parameters according to the application. The experimental case studies with alumina/water nanofluid and magnetic nanofluid are considered to discuss the various effects on the heat transfer. The effect of concentrations, shape and size of the nanoparticles is discussed in the case studies.

The present paper investigates the buoyancy induced flow and heat transfer in a square enclosure filled with Fe3O4/water nanofluid heated by mutually orthogonal heaters and symmetrically cooled by sidewalls under the influence of a strong uniform magnetic field. The nanofluid is experimentally synthesized by two-step method and the different thermophysical properties are measured. These experimentally determined properties are compared with the classical correlations available in the literature. Those correlations are found to underpredict the dynamic viscosity and thermal conductivity of the nanofluid. The error related to the use of the classical correlations is determined and it increases with the volume fraction. Hence, the experimentally determined properties are directly used in the numerical simulation. The governing equations in the form of nondimensional stream function, vorticity, and energy equations containing experimentally determined properties are solved using the finite difference method (FDM). The consequence of different factors like positions of the heaters, varying range of Rayleigh number (103 ≤ Ra ≤ 106), the extremely low volume fraction of nanofluids (0 ≤ φ ≤ 0.0007), and Hartmann number (0 ≤ Ha ≤ 75) on the heat transport is studied and reported. The study explains and analyzes the streamlines and isotherms at different conditions. The results show that the positions of the horizontal and vertical heater have a significant effect on heat transfer and fluid flow inside the enclosure. Furthermore, the increase in Ha enervates the strength of flow and it leads to the deterioration of heat transfer.

Natural convection cooling of an electronic component in an electronic device using water-based Fe3O4 magnetic nanofluids is studied under the presence of the magnetic field. The heated vertical electronic component in an enclosure type electronic device with a magnetic field source is used as a model for the study. Different samples of Fe3O4-water nanofluid are prepared using different surfactants and the stability of those samples are estimated using visualization and zeta potential technique. Thermal properties of the stable sample of magnetic nanofluid are precisely measured. The experimentally measured properties are used for further theoretical study. The natural convection is characterized in terms of the relative position of the magnetic source and the electronic component, the strength of the magnetic field, and the magnetization of the nanofluids. Nine different combinations of the position of the magnetic source and the electronic component have been compared with the case in which there is an absence of the magnetic field. The dimensionless number used in this investigation are Rayleigh number (103 ≤ Ra ≤ 106), magnetic numbers (Mn = 100, 500, and 1000), and Hartmann Number (0 ≤ Ha ≤ 100). The position of the magnetic source with respect to the electronic component significantly affects the rate of heat transfer. The effect is more pronounced when the magnetic source is placed below any of the two vertical walls of the enclosure. The fluid flow is observed distorted near the magnetic source when the Ha is increased. The increment in the magnetic number strengthens the flow, which leads to the enhanced heat transfer rate.

The experiments are conducted to investigate the effect of temperature, magnetic field, and nanoparticles on the effective thermophysical properties (thermal conductivity, viscosity and density) of the magnetic nanofluids. The Fe3O4 magnetic nanoparticles are dispersed in the water at various concentrations and the resulted suspensions are assessed in the temperature range 10-70 degrees C and under the presence of an external magnetic field range from 0 to 750 Gauss. The different parameters have observed the significant effects on the thermal conductivity, viscosity and density of these colloidal suspensions. The experiments have revealed that the thermal conductivity is enhanced with nanoparticle concentration, temperature and magnetic field. The new empirical correlations using Buckingham-Pi theorem and analytical approach have been proposed and discussed comprehensively for the effective thermal conductivity for such magnetic suspensions under the presence of a magnetic field. The viscosity of the colloidal suspension is shown significant enhancement with nanoparticle concentration and decrement with increasing temperature. The empirical correlation for the viscosity is reported and elucidates the temperature dependence of the viscosity. However, the density for these suspensions shows only a trivial enhancement with concentrations.

The need of advanced heat transfer fluid leads to develop nanofluids. Nanofluids are the conventional heat transfer fluids containing solid nanoparticles. The chapter deals with basic introduction of nanofluids, development history of nanofluids and different classifications of nanofluids. Different conventional fluids have been used as the working fluid to transfer the heat in various processes. As a working fluid, water is used extensively due to its immense availability, but not considered as an efficient heat carrier due to low thermal conductivity. The alternates of water, like engine oil, ethylene glycol, etc., are also applied to the various applications, but higher viscosity and toxic nature have restricted the employability of these substitutes in the heat transfer processes. Thus, water has remained the only accessible option as working fluids. However, during the last few decades, it is observed by the researchers that these conventional working fluids have low thermophysical properties which confine the convection heat transfer rate. Hence, by improving the thermophysical properties of the working fluids, the heat transfer can be increased. Nanofluids could be a new dawn to the highly efficient heat flow technologies

After discussing the various thermophysical properties of the nanofluids and the effects of various parameters on these thermophysical properties, we are now entering in the field of forced convective heat transfer. The researchers across the worlds have found out that nanofluids (the colloidal suspension of nano-sized particles into the conventional base fluid) reveals some exciting results for the convective heat transfer. The chapter summarizes and analyzes the various experimental and numerical results reporting the convective heat transfer using nanofluids. The enhancement in the heat transfer by using nanofluids is not a common conclusive argument have reported by the researchers. Some researchers have reported the deterioration, and some shows anomalous enhancement in the heat transfer. The conclusion on the mechanism behind the change in the convective heat transfer is still not clear using the nanofluids. On the other hand, pressure drop enhancement is reported by the researchers while using the nanofluids, and it is increased with the concentration. At high particle concentration, the increment is noted around 5% compared to water. The dimensionless number such as Nusselt number and Reynolds number are used to study the convective heat transfer. The fundamentals of the heat transfer and nanofluids have been discussed already in the previous chapters. This chapter discusses the convective heat transfer and pressure drop characteristics in different flow regimes of the internal forced convection.

Numerous studies have been conducted on the characterization of nanofluids, including the measurement of thermophysical properties of nanofluids. The chapter includes the discussion on the various thermophysical properties of the nanofluids. The thermophysical properties mainly comprise thermal conductivity, viscosity, heat capacity and density. Thermal conductivity and viscosity play a vital role to enhance the convection heat transfer in nanofluids. The effects of various parameters on the thermal conductivity, viscosity, density and specific heat of the nanofluids are epitomized in a systematic manner. A colloidal suspension of nanoparticle into the base fluid can adjust the thermophysical properties to the desired requirement. Many models have been reported in the literature to analytically estimate the thermophysical properties (especially thermal conductivity) of colloidal suspension, but still there is some contradiction between the theories. Some of the important experimental studies on the thermal conductivity and other properties of nanofluids are summarized.

The current article discussed the research done on the engine cooling or related to engine cooling using nanofluids into different sections. Nanofluid, a colloidal suspension of nanometer sized tiny particles into currently coolant fluids are considered as prospective next generation working fluid to enhance the convective heat transfer. The paper begins with the introduction of evolving history of car radiator, coolants and nanofluids. Then preparation and characterization of nanofluids based on engine coolant has been comprehensively discussed. The article provides an essential comparison, analysis and guidelines for the development of amicable future of nanofluids as a coolant.

We report the experimental measurement of the temperature fluctuation in the vicinity of different zones of the thermal boundary layer in water-filled open cubic cavities heated from below and open at the top. The experiments are performed on the cubic cavity of aspect ratio 1 and lateral dimension 30 mm; the results of our previously reported open cubic cavities of aspect ratio 1 and lateral dimensions (120 mm and 240 mm) are also considered here. The transient nature of the temperature has been measured from the temperature–time series recorded across the central axis of the cavity at different vertical positions z from the heated bottom plate. The Prandtl number and Rayleigh number ranges reported in this paper are 4 ≤ Pr ≤ 6 and 105 ≤ Ra ≤ 109, respectively. The different basic statistical properties, of temperature fluctuation such as mean temperature, root mean square, and probability density function, are studied and discussed. The power-law of power spectral density of the temperature fluctuations at different regions of the thermal boundary layer is studied, and the different roles of rate are compared with the previously established theories and models. The validity criteria for the Oberbeck–Boussinesq approximation are fulfilled. The trend of the dimensionless Nusselt number (Nu) representing the global convective heat transfer is obtained and discussed. We also study the variation in Raδth−1 3 for the heat transfer representation in the range of 0.04–0.24, where δth is the boundary layer thickness.

The car radiators or any vehicle engine thermal management system is evolving since its beginning, to achieve a sustainable, energy efficient stage. In this peculiar journey, the nanofluids playing a vital role of coolants to enhance the exchange rate of heat transfer to make the radiator cooling system effective. The current article is summarized and talk over radiator cooling of engine in vehicles using nanofluids. The nanoparticles present in the nanofluids have higher thermal properties which contributes to higher heat transport. The article opens with the introduction of the nanofluids, coolants and a summarized evolving history of a car radiator. The next sections include the overview of synthesis and characterization of nanofluids based on engine coolant followed by the heat transfer analysis. Effects on the thermophysical property (Thermal conductivity and Viscosity) of fundamental parameters which can be avoidable while selecting parameters are discreetly discussed. The fundamental of convective heat transfer and the mechanism behind the change in convective heat transfer is discussed with non-dimensional numbers. A number of suggestion and guidelines are reported for the better performance and results with nanofluids. The article provides an essential assessment of the nanofluids in the radiator cooling and the paper also provide a detail guideline for the development of amicable future of nanofluids in the heat transfer application.

We report the modulation in dielectric properties of a ferroelectric liquid crystal (FLC) by using carbon quantum dots (CQDs) of size ∼4–5 nm. The appearance of a low frequency dielectric relaxation mode in the FLC, called the partially unwound helical mode (p-UHM), is controlled by CQDs with a FLC material in two different ways. Firstly, CQDs are dispersed into the bulk of the FLC before filling into a sample cell, and secondly, they are deposited onto the surface of a substrate. In both cases, the p-UHM has been found suppressed due to the modulation of a helicoidal structure at the interface of the FLC and the surface of the substrate of the sample cell. It has also been confirmed that CQDs at the interface of the FLC and the surface of the substrate have not affected the intrinsic properties of the FLC material. On the other hand, CQDs in the bulk of the FLC have shown remarkable variations in the fundamental properties of the FLC material. The suppression of the dielectric mode is confirmed by high-resolution dielectric spectroscopy, optical textures, and contact angle measurements. The concept of appearance and disappearance of the p-UHM process leads to the understanding of FLC systems in confined geometries for various display and non-display applications.

Rising concern about the use of non-permitted colourants, in common food items such as dals and green vegetables sold in Indian markets, have led to a demand for low-cost point-of-use chemical analysis tools. Conventional food-analysis techniques involving tedious sample preparation protocols are not suited for in-field applications. Surface Enhanced Raman Spectroscopy (SERS) is an analytical technique that is well-suited for point-of-use chemical analysis with molecular level detection capability, which can also serve as a quality assurance tool for businesses. Effective and rapid signal collection from a large-area sample within a field-setting using disposable, low-cost SERS substrates is a key challenge in implementing such a solution. Herein, we demonstrate the use of inkjet-printed thin films comprising of robust nanostructuredsilver as flexible, paper-based SERS (P-SERS) swabs for the direct detection of Metanil Yellow (MY) from toor dal (yellow split pigeon peas) samples and Malachite Green (MG) from green peas and green chillies. The macroscopic uniformity of these thin-films in combination with a portable Raman spectrometer equipped with orbital raster scanning (ORST) technology for signal collection results in an unprecedented precision (RSD similar to 1.6%) upon characterizing samples saturated with Rhodamine-6G (R6G), a standard Raman probe. As several food-cleansing products have appeared in the marketplace, the adulterant removal efficacy of some commercially available 'washes' as well as products such as 'ozoniser', which was determined by SERS characterization of swabs before and after use, is also reported. (C) 2019 Elsevier B.V. All rights reserved.