Smart Temperature Sensors

Many real-world applications depend on temperature sensing and/or control. This includes a wide range of industrial processes, chemical reactors, and SCADA systems, in addition to other physical, mechanical, and biological systems. With the advancement of technology, it became possible to produce a new generation of smart and compact temperature sensors, which are capable of providing digital outputs that are more accurate, robust, and easily interfaced and integrated into measurement and control systems. This chapter first surveys traditional analog temperature sensors, such as RTDs and thermocouples, to provide a strong motivation for the need to adopt better and smarter techniques that mainly rely on digital technology (e.g., CMOS designs). Different interfacing techniques that do not need ADCs are introduced, including the programmable Arduino microcontrollers. Different applications will be explored that include automotive accessories, weather forecast, healthcare, industrial processing, firefighting, and consumer electronics. Both wired and wireless technologies, including the IoT, will be investigated as means for transmitting the sensed data for further processing and data logging. A special case study to provide information redundancy in industrial SCADA systems will be analyzed to illustrate the advantages and limitations of smart temperature sensors. The chapter concludes with a summary of the design effort, accuracy, performance, and cost effectiveness of smart temperature sensors while highlighting future trends in this field for different applications.

Design Techniques for Microfluidic Devices Implementation Applicable to Chemical Analysis Systems

This chapter provides a guide for microfluidic devices development and optimization focused on chemical analysis applications, which includes medicine, biology, chemistry, and environmental monitoring, showing high-level performance associated with a specific functionality. Examples are chemical analysis, solid phase extraction, chromatography, immunoassay analysis, protein and DNA separation, cell sorting and manipulation, cellular biology, and mass spectrometry. In this chapter, most information is related to microfluidic devices design and fabrication used to perform several steps concerning chemical analysis, process preparation of reagents, samples reaction and detection, regarding water quality monitoring. These steps are especially relevant to lab-on-chip (LOC) and micro-total-analysis-systems (μTAS). μTAS devices are developed in order to simplify analytical chemist work, incorporating several analytical procedures into flow systems. In the case of miniaturized devices, the analysis time is reduced, and small volumes (nL) can be used.

Analysis of Hydrodynamics and Mass Transfer of Gas-Liquid and Liquid-Liquid Taylor Flows in Microchannels

Analysis of hydrodynamics and mass transfer Taylor flows in micro channels of both gas-liquid and liquid-liquid systems on the basis of classical theoretical approach with some simplifying assumptions was performed. Results of theoretical analysis for description of hydrodynamic parameters and mass transfer characteristics were confirmed by comparison with the author's own and available in literature experimental data. It was shown that the main parameters of two-phase Taylor flows could be quite precisely described theoretically: mean bubble/droplet velocity, liquid film thickness, real gas holdup (which is always smaller than so-called dynamic holdup), pressure drop. Peculiarities of liquid-liquid flows compared to gas-liquid Taylor flows in capillaries are discussed. Wettability effect on hydrodynamics was examined. Tools of mass transfer intensification of gas-liquid and liquid-liquid Taylor flow in micro channels are analyzed. Three-layer model for heat and mass transfer has been proposed and implemented for the case of solid-liquid mass transfer for gas-liquid Taylor flows; optimal process conditions for this process are found theoretically and discussed from physical point of view.

Computer Simulation of the Aerodisperse Systems Hydrodynamics in Granulation and Drying Apparatus

The chapter presents validation of the selection criteria for the construction of the granulation and drying equipment. New forms of the organization of the flows motion in a fluidized bed regime are offered. The steering mechanisms for the motion and the residence time of the disperse phase in a workspace of the apparatus are described. The results of the simulation of the hydrodynamic conditions for the motion of the directional gas flow and the two-phase aerodisperse system are presented. Based on the simulation results, various constructions of the apparatus components are offered. The well-minded construction of the workspace of the apparatus helps to achieve optimized consumption of the heating agent and the minimal residence time of the disperse phase in the apparatus. The computer simulation allowed the authors to offer an algorithm of the optimization calculations of the granulation and drying equipment. New constructive solutions to perform the granulation and the drying processes in the devices with a directional fluidized bed are offered.

Experimental and Numerical Analyses of a Micro-Heat Exchanger for Ethanol Excess Recovery From Biodiesel

The use of micro-heat exchangers increased with the advancement of microfluidics. These microdevices present some advantages like elevated surface area-to-volume ratio resulting in high heat transfer rates. Micro-heat exchanger with phase change is a new application of such devices. The simultaneous momentum, heat, and mass transfer at microscale still require investigations due to the inherent complexity. The main goal of the chapter is to demonstrate experimentally and numerically the capability of the micro-heat exchanger use in the continuous process of ethanol excess recovery from the biodiesel. The influence of flow rate, ethanol/biodiesel molar ratio, and temperature on the ethanol evaporation performance was evaluated. The flow rate and the ethanol/biodiesel molar ratio influenced negatively the evaporation. In contrast, the temperature was affected positively. The mathematical model was able to capture the main features of the continuous evaporation; however, further improvements must be performed in order to consider the thermodynamics characteristics.

Immiscible Two-Phase Parallel Microflow and Its Applications in Fabricating Micro- and Nanomaterials

The immiscible two-phase flow behaves nonlinearly, and it is a challenging task to control and stabilize the liquid-liquid interface. Parallel flow forms under a proper balance between the driving force, the friction resistance, and the interfacial tension. The liquid-solid interaction as well as the liquid-liquid interaction plays an important role in manipulating the liquid-liquid interface. With vacuum-driven flow, long and stable parallel flow is possible to be obtained in oil-water systems and can be used for fabricating micro- and nanomaterials. Ultra-small Cu nanoparticles of 4~10 nm were synthesized continuously through chemical reactions taking place on the interface. This makes it possible for in situ synthesis of conductive nanoink avoiding oxidation. Well-controlled interface reactions can also be used to produce ultra-long sub-micro Cu wires up to 10 mm at room temperature. This method provided new and simple additive fabrication methods for making integrated microfluidic devices.

An Introduction to Computational Fluid Dynamics and Its Application in Microfluidics

The chapter aims to introduce the computational fluid dynamics (CFD). A review was provided, outlining its development and applications on chemical engineering and microfluidics. The fundamental points of the CFD, listing the advantages and precautions of this numerical technique were provided. The description of CFD methodology including the three essential stages (pre-processing, solving, and post-processing) was made. The fundamental transport equations—total mass (continuity), momentum, energy, and species mass balances—and the usual boundary conditions used in CFD were explained. The main approaches used in multicomponent single-phase flows, single-phase flow in porous media, and multiphase flows in microscale were detailed, as well as the numerical mesh types and its quality parameters. A brief introduction of finite volume method (FVM) used by most of the available CFD codes was also performed, describing the main numerical solution features. Finally, the conclusions and future prospects of CFD applications are exposed.

Heat and Mass Transfer Characteristics of Evaporating Falling Films

This chapter presents a numerical investigation of heat and mass transfer characteristics during the evaporation of liquid films in vertical geometries. A two-phase model is developed to simulate laminar film evaporation into laminar gas flow. The liquid film evaporation is evaluated under adiabatic and heated wall conditions for both pure and binary liquid film. The model is based on a finite difference method to solve the governing equations of the two phases. The obtained results concerns two industrial processes. The first part of the chapter is devoted to the analysis of the thermal protection of vertical channel wall, while the second part is devoted to the desalination process by falling liquid film. The simulations results allowed the determination of the optimal operating conditions for both processes.

2D Numerical Study of a Micromixer Based on Blowing and Vortex Shedding Mechanisms

In this chapter, a numerical study and assessment of the mixing efficiency of a novel microfluidic device for mixing two fluids are presented. The device under study consists of a two-dimensional straight microchannel with a square pillar centered across the channel. The main fluid flows through the microchannel from the main inlet to the outlet, while the second fluid is injected through the pillar as two small jets at its upstream corners. For different values of the Reynolds number, intensity ratio between the jets and the main channel stream and jets injection angle, the authors have conducted several numerical simulations to characterize both the mixing efficiency and the required input power to make the fluids flow. The optimum configuration has been revealed for high values of the Reynolds number, low intensity ratios, and high injection angles. Thanks to vortex shedding and the corresponding downstream oscillations, a mixing efficiency of around 90% can be reached. The worst mixing efficiency is obtained for a configuration without vortex shedding, having a mixing efficiency of only around 2%.

Analytical and Numerical Modelling of Liquid Penetration in a Closed Capillary

The chapter explores the dynamics of liquid penetration in a closed end vertical capillary. This model is very important for impedance spectroscopy methodology where oxidized porous silicon provides an in vitro medium, and one important criteria of this methodology is the liquid penetration depth inside the silicon pores as the impedance is greatly affected by this penetration depth. This problem is also important in order to understand how the presence of entrapped air inside a micro pore can influence the dynamics of capillary flow. For this purpose, the model is studied both analytically and numerically. In this study, different pore size (500 nm and 2 µm diameter) with equal pore depth (~10 µm) have been used. Finally, the analytical solution is compared with the numerical results. In addition, the linearization of the system is also investigated and found the critical viscosity of which demarcates the over-damped and under-damped regimes. Further, this study is extended by incorporating the dynamic contact angle effects on the meniscus dynamics.