Measurement Of Thermophysical Properties Research Articles

Some experimental progresses in the study of self-rewetting fluids for the SELENE experiment to be carried in the Thermal Platform 1 hardware

SELENE (SELf-rewetting fluids for thermal ENErgy management) is a microgravity experiment proposed to the European Space Agency (ESA) in response to the Announcement of Opportunities for Physical Sciences. Main objectives of the microgravity research onboard the International Space Station (ISS) include the quantitative investigation of heat transfer performances in model heat pipes and validation of adequate theoretical and numerical models. In particular the research is focused on “self-rewetting fluids”, i.e. fluid mixtures with unusual surface tension properties. This article summarizes preliminary ground-based research activities in preparation of the microgravity experiments. They include: (1) thermophysical properties measurements; (2) study of thermo-soluto-capillary effects in micro-channels; (3) numerical modeling; (4) measurements with optical (e.g. interferometric) and intrusive techniques; (5) surface tension-driven effects and thermal performances test on different capillary structures and heat pipes; and (6) breadboards development and support to definition of scientific requirements.

Measurement of thermophysical properties and modeling for pseudo-binary mixtures of n-decane and Athabasca bitumen

Ultra heavy oil and bitumen contain high molecular weight compounds that resulted in more viscous fluids than most conventional crude oils. For the production and transportation of such heavy fluids, it is necessary to reduce their viscosity. The dilution of bitumen with liquid solvent is one of the practical methods to reduce the bitumen viscosity to a desired level. In this manuscript, the physical properties (density and dynamic viscosity) of a bitumen sample from Athabasca field and its diluted mixtures with n-decane have accurately been measured. The measurements have been taken under conditions applicable for both in situ recovery methods and pipeline transportation. The experiments have been conducted in the temperatures varying from ambient temperature up to 344K and at pressures up to 10MPa and on mixtures with different weight fractions of n-decane (0.05, 0.1, 0.2, 0.3, 0.4, and 0.5). The generated experimental density and dynamic viscosity data for raw bitumen and its mixtures with n-decane were evaluated with predictive schemes as well as with correlation models. The influence of pressure, temperature, and solvent weight fraction on the density and dynamic viscosity of the mixtures was considered in the models and evaluated from the experimental results. The results indicated that power law model could correlate the dynamic viscosity of Athabasca bitumen and n-decane mixtures well over the studied conditions. The density data were also well predicted with an equation that assumes no volume change upon mixing occurs.

A new method to determine thermophysical properties of PCM-concrete brick

Accurate measurement of thermophysical properties of PCM-concrete brick is very important for simulation and evaluation of its energy saving performance. However, there is currently no effective way to accurately measure thermophysical properties of PCM-concrete brick. First we analyzed the shortcomings of using traditional testing methods to measure thermophysical properties of PCM-concrete brick. We then proposed a new method based on the inverse problem, which deals with the measurements of thermal conductivity and specific heat of PCM-concrete brick during the phase change process. The equivalent specific heat distributions of 4wt% and 6wt% PCM-concrete brick were determined using this method. We found that the accuracy (the relative error of the calculated cp based on the inverse problem and their real values ranges from 10.43% to 19.4%) was acceptable for engineering use. The influences of the temperature segments span and optimization algorithms were analyzed. The results showed that the Sequential Quadric Programming (SQP) method provides the highest accuracy and least complexity compared with the Particle Swarm Optimization and Genetic Optimization methods. Finally, we suggested how to apply this method to other similar problems to extend its application scope.

Analysis of Marine Diesel Fuel with the Advanced Distillation Curve Method

Ocean-going ships burn heavy fuel oil. The combustion of heavy fuel oil in marine diesel engines emits nitrogen oxides, sulfur oxides, and particulates into the air. Growing public concern over air quality has led to increased scrutiny of heavy fuel oil as a source of air pollutants, with calls for greater regulation of its composition to safeguard public health and the environment. Heavy fuel oil is a complex mixture, prepared by blending residual oil from petroleum distillation with more volatile fractions to meet industry standards. The fuel composition has a significant effect on the type and amount of combustion products produced, but the complexity of heavy fuel oil blends has hindered past efforts at analysis. The advanced distillation curve (ADC) method was developed as a complex fluid analysis protocol, combining thermophysical and chemical properties measurement. We applied the ADC method, under reduced pressure, to a sample of IFO 380 intermediate fuel oil to characterize its volatility and com...

New Facilities for the Measurements of High-Temperature Thermophysical Properties at LNE

LNE is expanding the measurement capabilities of its metrological platform devoted to the determination of the main thermophysical properties of materials toward very high temperatures. In particular, two facilities have been developed for measuring the directional spectral emissivity up to \(1500\,^{\circ }\)C and the thermal diffusivity up to \(3000\,^{\circ }\)C in the case of homogeneous solid materials and of thermal barrier coatings. These developments have required in particular the design of specific heating systems which are based either on the use of a lamp image furnace or on inductive heating technology. These works are performed in the framework of two international projects related to the thematic “Energy”, and which involve essentially European national metrology institutes. The availability of reference metrological facilities for the characterization of thermophysical properties of materials at high temperature with controlled uncertainties will enable ultimately the improvement of the traceability in academic and industrial research laboratories for measuring these quantities. This paper gives a detailed description of these metrological facilities and of the associated measurement methods.

Inverse Identification of Temperature-Dependent Volumetric Heat Capacity by Neural Networks

An artificial neural network (NN)-based solution of the inverse heat conduction problem of identifying the temperature-dependent volumetric heat capacity function of a solid material is presented in this paper. The inverse problem was defined according to the evaluation of the BICOND thermophysical property measurement method. The volumetric heat capacity versus temperature function is to be determined using the measured transient temperature history of a single sensor. In this study, noiseless and noisy artificial measurements were generated by the numerical solution of the corresponding direct heat conduction problem. The inverse problem was solved by back-propagation and radial basis function type neural networks applying the whole history mapping approach. The numerical tests included the comparison of two different data representations of the network inputs (i.e., temperature vs. time and time vs. temperature) and accuracy analysis of the two network types with noiseless and noisy inputs. Based on the results presented, it can be stated that feed-forward NNs are powerful tools in a non-iterative solution of function estimation inverse heat conduction problems and they are likely to be very effective in evaluation of real measured temperature histories to determine the volumetric heat capacity as an arbitrary function of temperature.

Modeling of EML in Combined AC/DC Magnetic Fields as the Basis for Microgravity Experiments

This article contains a review of research activity in the University of Greenwich to model the effects of static or DC magnetic fields on the characteristics of EM-levitated melts. The general idea is that the presence of a DC field will damp out the velocities inside a levitated droplet and so lead to more accurate thermophysical property measurements, especially those of viscosity and thermal conductivity that will otherwise be affected by turbulence. The technique is in fact used successfully in terrestrial experiments, and this study sets out to examine its applicability in the case of microgravity. An accurate spectral-collocation numerical scheme is used to couple dynamically the velocity, temperature and magnetic fields, so that internal velocity and liquid envelop changes of a suspended “spherical” droplet can be observed as a function of applied AC and DC fields, with or without gravity.

CO2Mix Project: Experimental Determination of Thermo Physical Properties of CO2-Rich Mixtures

The CO2Mix project is established in order to fill important knowledge gaps regarding thermophysical properties of CO2-rich mixtures relevant for CCS conditioning and transport. Even small amounts of impurities can have a large effect on these properties and hence on the design of process equipment and flow assurance calculations. Hence, accurate models backed up by experimental data of high quality are required for efficient and safe design and operation of CCS infrastructure and equipment. In the CO2Mix project, SINTEF Energy Research, Norwegian University of Science and Technology (NTNU) and Ruhr-Universitat Bochum (RUB) will perform accurate measurements of phase equilibria, density, and speed of sound. In this paper, the need for measurement of thermo-physical properties will be discussed, and the experimental setups will be described.

VISCOSITY MEASUREMENT USING BREAKUP OF A LEVITATED DROPLET BY ROTATION

Thermophysical property measurement without container is used for high-temperature molten material. A microgravity environment is useful in order to achieve a containerless condition, and the levitation technique can also be used for containerless processing even on the ground. The purpose of this study is to establish a new measurement technique to measure viscosity in the moderate viscous range, which has no conventional measurement methods. In this study, a droplet is levitated by electrostatic force and induced to rotate. The dynamic behavior of the levitated droplet shape is observed, and the viscosity measurement is obtained by using breakup of the levitated droplet depending on the viscosity.

Lubricant Chemistry and Rheology Effects on Hydraulic Motor Starting Efficiency

The starting efficiency of hydraulic motors is critically important because it is often a limiting criterion in hydraulic system design. One means of improving starting efficiency is to optimize the chemistry of the lubricating fluid. To understand the potential effect of new hydraulic fluid formulations, it is necessary to characterize their physical properties and performance from multiple perspectives. In this work we report a comprehensive characterization of five lubricating fluids with the same viscosity but different additive and base stock compositions. Analysis includes measurement of frictional behavior, thermophysical and rheological properties, and mechanical efficiency in three different hydraulic motors. Trends were analyzed and correlations between the various fluid properties were identified. The results illustrate the importance of operation-specific fluid formulation and comprehensive lubricant characterization.

Guest Editorial for the Special Issue on Micro/Nanoscale Transport Phenomena

Guest Editorial for the Special Issue on Micro/Nanoscale Transport Phenomena

Chemical and Thermophysical Characterization of 1,3,5-Triisopropylcyclohexane

The complex nature of finished fuels makes definitive studies on composition and combustion properties very difficult and uncertain. This has led to the adoption of fuel surrogate mixtures in such studies. The development of a surrogate mixture is itself a nontrivial process, and a surrogate mixture is often developed specifically for a given purpose. Often, thermophysical property surrogate mixtures cannot be used for examination of combustion properties, and vice versa. Surrogates range in complexity from a single component to complex mixtures containing 20 or more components. A recent study on surrogate mixture development for diesel fuel used state-of-the-art techniques of 13C and 1H nuclear magnetic resonance (NMR) spectroscopy and the advanced distillation curve to characterize fuel composition and volatility, respectively. This work indicated the need for a multiply substituted, low cetane number, high molecular mass monocycloalkane surrogate mixture component. The addition of 1,3,5-triisopropylcyclohexane as a palette component was chosen to serve this need. Before this component can be used in any modeling or experimental effort, we first require some basic chemical and thermophysical properties. In this paper, we present chemical characterization results from gas chromatography with mass spectrometry, 13C NMR spectrometry, isothermal Kovats' retention indices at (150 to 225) °C (on 5 % phenyl-95 %-dimethyl polysiloxane), and refractive indices at (20, 25, and 30) °C. We also present ambient pressure thermophysical property measurements: density, speed of sound, and derived adiabatic compressibility from (5 to 70) °C and kinematic viscosity from (20 to 100) °C. These properties and characterization parameters are critical to the successful application of 1,3,5-triisopropylcyclohexane in experimental and modeling studies of surrogate diesel fuels.

Thermal and mechanical properties of maize fibres–high density polyethylene biocomposites

In recent years, considerable attention has been given to the development and utilization of natural fibres. This study examines the thermal properties of maize thermomechanical fibre reinforced high density polyethylene composites with competitive mechanical properties. The composites were produced by six different steps, namely: drying, cutting, mixing, compounding, pelletizing and injection moulding. Composite samples with fibre contents in the range 10–40 wt% were chosen to observe their effect on thermal and mechanical properties as the fibre content was increased. Measurements of thermophysical properties were obtained using periodic temperature ramp method. The material characterization was performed on a temperature range that extends from −20℃ to 120℃. It was found that the thermal conductivity and diffusivity of the composites decrease with fibre loading. The results showed that when the temperature is increased, a significant increase of both thermal effusivity and the factor [Formula: see text] was observed. A high-quality dispersion and adhesion of maize fibre in the high density polyethylene matrix was indicated by scanning electron microscopy. Good mechanical performance of the obtained composites was established considering the stress transfer at fibre–matrix interface.

Simultaneous Identification of Temperature-Dependent Thermal Properties via Enhanced Genetic Algorithm

Simultaneous inverse identification of the temperature-dependent volumetric heat capacity and thermal conductivity of a solid material based on transient temperature histories was studied. The inverse problem was defined according to the evaluation of the BICOND thermophysical property measurement method. The material property functions were defined by several data points with linear interpolation between them. In this way, no previous information is needed about the expected temperature dependency of the material property functions. The inverse problem was solved by a real-valued genetic algorithm using simulated measurement results. New genetic operators (smooth initialization and smooth mutation) were developed and applied. The accuracy of the inverse solution was studied in two test cases including linear, square, and sinusoidal functions. The effects of regularization and random noise in the temperature histories were also analyzed. Based on the results, the proposed method is likely to be effective in evaluation of real measured temperature histories to simultaneously determine temperature-dependent thermophysical properties.

Lorentz force sigmometry: A contactless method for electrical conductivity measurements

The present communication reports a new technique for the contactless measurement of the specific electrical conductivity of a solid body or an electrically conducting fluid. We term the technique “Lorentz force sigmometry” where the neologism “sigmometry” is derived from the Greek letter sigma, often used to denote the electrical conductivity. Lorentz force sigmometry (LoFoS) is based on similar principles as the traditional eddy current testing but allows a larger penetration depth and is less sensitive to variations in the distance between the sensor and the sample. We formulate the theory of LoFoS and compute the calibration function which is necessary for determining the unknown electrical conductivity from measurements of the Lorentz force. We conduct a series of experiments which demonstrate that the measured Lorentz forces are in excellent agreement with the numerical predictions. Applying this technique to an aluminum sample with a known electrical conductivity of σAl=20.4MS/m and to a copper sample with σCu=57.92MS/m we obtain σAl=21.59MS/m and σCu=60.08MS/m, respectively. This demonstrates that LoFoS is a convenient and accurate technique that may find application in process control and thermo-physical property measurements for solid and liquid conductors.

Inverse identification of temperature-dependent thermal conductivity via genetic algorithm with cost function-based rearrangement of genes

A new application of the cost function-based rearrangement of genes (proposed by Liu (2008) [1]) is presented in this paper through the genetic algorithm-based solution of the inverse heat conduction problem of identifying the temperature dependent thermal conductivity of a solid material using transient temperature histories. The inverse problem was defined according to the evaluation of the BICOND thermophysical property measurement method. Through the solution of the inverse problem (using simulated measurements), different approaches of the application of the rearrangement of genes were studied and compared. Application of the rearrangement significantly improved the convergence performance and accuracy of the inverse solution compared to a real-valued genetic algorithm, which was adapted to the problem by the authors. In the algorithm that performed best, the rearrangement was applied in an approach different from Liu’s. The effect of random noise added to the temperature history and the effect of regularization was also studied. With significant improvement in computational efficiency, the proposed algorithm is likely to be very effective in evaluation of real measured temperature histories to determine thermophysical properties.

In situ droplet surface tension and viscosity measurements in gas metal arc welding

In this paper, we present an adaptation of a drop oscillation technique that enables in situ measurements of thermophysical properties of an industrial pulsed gas metal arc welding (GMAW) process. Surface tension, viscosity, density and temperature were derived expanding the portfolio of existing methods and previously published measurements of surface tension in pulsed GMAW. Natural oscillations of pure liquid iron droplets are recorded during the material transfer with a high-speed camera. Frame rates up to 30 000 fps were utilized to visualize iron droplet oscillations which were in the low kHz range. Image processing algorithms were employed for edge contour extraction of the droplets and to derive parameters such as oscillation frequencies and damping rates along different dimensions of the droplet. Accurate surface tension measurements were achieved incorporating the effect of temperature on density. These are compared with a second method that has been developed to accurately determine the mass of droplets produced during the GMAW process which enables precise surface tension measurements with accuracies up to 1% and permits the study of thermophysical properties also for metals whose density highly depends on temperature. Thermophysical properties of pure liquid iron droplets formed by a wire with 1.2 mm diameter were investigated in a pulsed GMAW process with a base current of 100 A and a pulse current of 600 A. Surface tension and viscosity of a sample droplet were 1.83 ± 0.02 N m−1 and 2.9 ± 0.3 mPa s, respectively. The corresponding droplet temperature and density are 2040 ± 50 K and 6830 ± 50 kg m−3, respectively.

Thermophysical Properties of the Refrigerant Mixtures R417A and R417B from Dynamic Light Scattering (DLS)

Dynamic light scattering (DLS) has been used for the measurement of several thermophysical properties of the refrigerant mixtures R410A and R407C. Thermal diffusivity and sound speed have been obtained by light scattering from bulk fluids for both the liquid and vapor phases under saturation conditions over a temperature range from about 290 K up to the liquid-vapor critical point. By applying the method of DLS to a liquid-vapor interface, also called surface light scattering (SLS), the saturated liquid kinematic viscosity and surface tension can be determined simultaneously. These properties have been measured for R410A and R407C from about 240 to 330 K and 240 to 350 K, respectively. The results are discussed in detail in comparison with literature data and with a simple prediction method based on the mass-weighted properties of the pure components expressed as functions of the reduced temperature.

Simultaneous Measurement of Thermophysical Properties of Tissue-Mimicking Phantoms for High Intensity Focused Ultrasound (HIFU) Exposures

Tissue-mimicking phantoms, including bovine serum albumin phantoms and egg white phantoms, have been developed for, and in laboratory use for, real-time visualization of high intensity focused ultrasound-induced thermal coagulative necrosis since 2001. However, until now, very few data are available concerning their thermophysical properties. In this article, a step-wise transient plane source method has been used to determine the values of thermal conductivity, thermal diffusivity, and specific heat capacity of egg white phantoms with elevated egg white concentrations (0 v/v% to 40 v/v%, by 10 v/v% interval) at room temperature (~20 °C). The measured thermophysical properties were close to previously reported values; the thermal conductivity and thermal diffusivity were linearly proportional to the egg white concentration within the investigation range, while the specific heat capacity decreased as the egg white concentration increased. Taking account of large differences between real experiment and ideal model, data variations within 20 % were accepted.

Measurement of Thermophysical Properties and Selection of Prediction Model for Selected Seafood

Measurement of Thermophysical Properties and Selection of Prediction Model for Selected Seafood