Aim of this experiment is to determine the coefficient of thermal conductivity of a bad conductor using lees disc apparatus. Equation 7, it implies that if the thermal conductivity of one rod was known, that of all others could be found. Be careful to avoid touching the hot surfaces of the steam generator, plastic tubing and the lees disk apparatus. Bocks apparatus this method is described in detail, because determining of thermal conductivity by this method is the part of laboratory lessons bm 10. Now here two question arises that what is lees disk, and what is the coefficient of thermal conductivity. Measuring thermal conductivity of fluids containing oxide. So, and for bad conductor generally the very common method is lee method or lees method. Species, concentration, and dispersion method on the thermal conductivity of nanofluids show all authors. To determine thermal conductivity of a bad conductor glass in form of a disc using. In the experiment, nanofluid consisting of deionized water and cuo nanoparticles is made by ultrasonic vibration. Request pdf lees and charltons method for investigation of thermal conductivity of insulating materials thermal property is the important material property for engineering and analysis.
Jul 30, 2018 lee s disc apparatus is a method of measuring the thermal conductivity of low conductivity materials such as glass or plastics or composite insulation boards. In this work, the authors present results of adaptation and testing of the hotwire method for determination for the thermalconductivity coefficient of nanofluids. Assessment of the thermal conductivity of local building. Nov 28, 2012 anna university lab experiment lees disc method experiment physics practical. Feel free to subscribe and please do hit the thumbs up button. The excellent stability of nanofluids was confirmed by zeta potential analysis. Lees disc apparatus consist of metallic disc say d and resting on it is a 5 cm deep hollow cylinder steam chamber. A mathematical model of heat transfer with allowance for free convection has been constructed to elucidate the parameters of an experimental setup and the range of its applicability. Absolute measurement of the thermal conductivity of electrically conducting liquids by the transient hotwire method. This showed that this method is an indirect method and does not give very accurate results 5. Thermal conductivity by lees method motivation and aim in this experiment the thermal conductivity of a bad conductor is measured.
Apr 12, 2014 thermal conductivity is a transport property of materials, defined as the ratio of the energy flux through a surface and the local temperature gradient. Measurement and prediction of the thermal and electrical. Physics made easyheat transfer thermal conductivity part. Lees disc method build your own thermal conductivity meter.
T 2 ideally the values for the thermal conductivity of copper obtained by the two methods, ka and kb, shouldbe the same. Toprakfabrication, characterization and thermophysical property evaluation of waterethylene glycol based sic nanofluids for heat. Determine the coefficient of thermal conductivity of a bad. Hi friends, in this video i have explained with an animation, how the thermal energy travels by conduction through a metal rod, and a practical feel for how searles apparatus works. It indicates the ability of a material to conduct heat. Effects of particle surface charge, species, concentration, and dispersion method on the thermal conductivity of nanofluids.
The flow rate should be such that the constant level cistern stays filled up to the level of the overflow pipe, but without a huge amount overflowing. Stability and enhanced thermal conductivity of ethylene. To determine thermal conductivity of bad conductor. Homogeneous and stable ethylene glycolbased sic nanofluids were fabricated.
Effects of particle surface charge, species, concentration. A number of techniques have been used to determine the ther mal conductivity of polymers, these being the hotline method,45 guarded hotplate,67 lee s disc method8 and the dsc. The temperature is made uniform by the high thermal conductivity of the brass. In this work, the thermal conductivity of kosso and mahogany wood were determined following the device of lee s disk. At the steady state, heat conducted through the bad conductor is equal to heat radiated from the lees disc. Based on maxwells electromagnetic theory of the relationship between particle mass fraction and conductivity in suspension, this paper presents a method to determine the stability of nanofluid, and validates it by experiment. Lees disc experiment for thermal conductivities thread starter dreamlord. Measurement of thermal conductivity of a poor conductor by lees disk method. So, in our experiment we are going to use this disc rubber disc. Oxide nanofluids were produced and their thermal conductivities were measured by a transient hotwire method. To get acquainted with the idea of dynamic equilibrium to investigate the characteristics of heat flow to determine the thermal conductivity of copper background. Thermal property is the important material property for engineering and analysis of insulating materials.
Lees disc method experiment physics practical youtube. There is little information about the origin of the method, although it was first reported around the year 1898 by. Pdf this experiment was carried out to design modified lees disc method of measuring the thermal conductivity of a poor conductor in the. Pdf thermal conductivity of glass saad muhammad ashraf.
Related threads on lees disc experiment for thermal conductivities. Stability and enhanced thermal conductivity of ethylene glycolbased sic nanofluids. The measured maximum relative thermal conductivity value was 16. Mar 10, 2016 hi friends, in this video i have explained with an animation, how the thermal energy travels by conduction through a metal rod, and a practical feel for how searle s apparatus works.
By measuring, and using lees apparatus the thermal conductivity k can be. To measure the thickness of the given bad conductor d. Lee s and charltons method for investigation of thermal conductivity of insulating materials. So, today we will discuss about this lees method, this method will be used to measure the measure the conductivity of thermal conductivity of bad conductor, right. Thermal conductivity of a poor conductor by lees and charltons method 11. In addition, it has radial holes to insert thermometers. What is thermal conductivity of a bad conductor by lees. High values of thermal conductivity imply higher rates of heat transfer and typically lower capital cost for the construction of a heat exchanger. Nov 23, 2012 what is thermal conductivity of a bad conductor by lee s disc method. This experiment was carried out to design modified lees disc method of measuring the thermal conductivity of a poor conductor in the form of a flat disc. Lees disc apparatus, bad conductor in the form of thin disc, steam box, two. The results were then compared with those obtained by the hot strip device. Measurement of thermal conductivity of polymers using an. Explain the principle of lee s disc method for determining conductivity of bad conductors.
In the experiment, we will use lees disc method to determine the thermal conductivity of a bad conductor, e. Oct 24, 20 hello, im doing my prep for my lab experiment tomorrow and have a few questions about the experiment. The thermal conductivity of cuo nanofluids was also studied. Thermal conductivity is the property of a material that indicates its ability to conduct heat. In the t type probe, a hot wire was supplied with a constant direct current, whose ends were connected to heat sinks to maintain the initial temperature. While thermal conductivity measures the rate at which thermal energy travels through a body, thermal diffusivity deals specifically with the associated rise in temperature measured in m 2 s. The experimental results show that these nanofluids, containing a small amount of nanoparticles, have substantially higher thermal conductivities than the same liquids without nanoparticles.
So, and for bad conductor generally the very common method is lee method or lees method, ok. Pdf lees and charltons method for investigation of. When steam is passed through the cylindrical vessel a steady state is reached soon. In the experiment, we will use lee s disc method to determine the thermal conductivity of a bad conductor, e. Measurement of thermal conductivity by lees method iiser pune. The most commonly used methods are searles method and lee s disc method, for good and bad conductors of heat, respectively. Lees disc apparatus is a method of measuring the thermal conductivity of low conductivity materials such as glass or plastics or composite insulation boards. Thermal conductivity of a bad conductor lees disc gsot. Measurement of the thermalconductivity coefficient of. Physics made easyheat transfer thermal conductivity. Make sure that the steam outlet tube from the apparatus goes to a sink.
Thermal conductivity of a good conductor by searles method. Experiment lees disc method thermal conductivity of bad. Thermal conductivity of a poor conductor by lees and. Lees and charltons method for investigation of thermal. The most commonly used methods are searles method and lees disc method, for good and bad conductors of heat, respectively. Lee s disc apparatus consist of a metallic disc resting on a 5 cm deep hollow cylinder steam chamber of same diameter. Lees disc apparatus consist of a metallic disc resting on a.
Once the steam is flowing well and thermometer t 1 has started to rise significantly, adjust the rate of water flow through the heat exchanger until it flows out of the outlet at a few hundred cm 3 in 35 mins the precise rate does not matter. Preparation and thermal conductivity of cuo nanofluid via. Measurement of the thermal conductivity of nanofluids by. Conduction takes place if there exists a temperature gradient in a solid or stationary fluid medium. Thermal conductivity is determined by the linear slope of. In this study, cuo nanofluid was synthesized with a wet chemical method. A thin, large surface area sample is used in the determination of thermal conductivity in order to quickly reach steady state. A method was developed to measure the longitudinal thermal conductivity tc of an individual fibre using a t type probe. Be careful to avoid touching the hot surfaces of the steam generator, plastic tubing and the lee s disk apparatus. In this study, thermal conductivities of insulating materials are determined and compared with the literature values. A slab or disc of material to be tested is placed between a steam chamber which maintains a constant.
Good agreement, within 2%, is found in recommended and published thermal. To determine the thermal conductivity of a bad conductor by lees disc apparatus. So, today we will demonstrate the measurement of thermal conductivity of bad. Lees disc method is a simple and effective way to calculate the thermal. Opposite to the searles bar experiment, lee s disc method is designed to calculate the thermal conductivity of primarily thermal insulators such as polystyrene.
Opposite to the searles bar experiment, lees disc method is designed to calculate the thermal conductivity of primarily thermal insulators such as polystyrene. The modified lees disc setup is equipped with various types of electrical device and probes. This method belongs to the steady state methods, guarded hot plate and is convenient for measuring of solid materials. Unanswered questions what evidence does coutu use to support her claim that improvisation requires resilience. Thermometers of 110 c ranges, stop watch, screw gauge, rough balance. Lees disc experiment for thermal conductivities physics forums.
Thermal conductivity is a transport property of materials, defined as the ratio of the energy flux through a surface and the local temperature gradient. Searles experiment for measuring the thermal conductivity. There is little information about the origin of the method, although it was first reported around the year 1898 by english scientist lee. Determination of thermal conductivity of abraka soil.
Lees disc method is used to measure the thermal conductivity of a poorly conducting material, such as glass, wood, or polymer. Sep 19, 20 lee s disc experiment for thermal conductivities. Keywords lees and charltons apparatus, steady state technique, thermal conductivity, thermal insulation. Searles experiment for measuring the thermal conductivity of. Lees and charltons method for investigation of thermal conductivity of insulating materials. To find the coefficient of thermal conductivity of a bad conductor by lees method. Diameter of the specimen slab s is measured with a scale. Download as docx, pdf, txt or read online from scribd. The lees disc experiment determines an approximate value for the thermal conductivity k of a poor conductor like glass, cardboard, etc. Explain the principle of lees disc method for determining. Sep 02, 2014 this experiment was carried out to design modified lee s disc method of measuring the thermal conductivity of a poor conductor in the form of a flat disc. Thermal conductivity of a bad conductor using lees method aim. Schematic diagram of a typical thermal conductivity lees.
To determine the coefficient of thermal conductivity of bad conductors by using lees disk method. Comparisons between experiments and the hamilton and crosser model show that the model can predict the thermal conductivity of. Explain the principle of lees disc method for determining conductivity of bad conductors. Thermal diffusivity the ratio of thermal conductivity k to the product of density. The heat, from a steam generator, is transmitted through a wide cross sectional area whi. Thermal conductivity measurement of an individual fibre. After measuring the thermal conductivity using radial heat flow method, the thermal conductivity was substituted into eq. A number of techniques have been used to determine the ther mal conductivity of polymers, these being the hotline method,45 guarded hotplate,67 lees disc method8 and the dsc.
The influences of synthesis parameters, such as kinds and amounts of copper salts, reaction time, were studied by xray diffraction xrd, transmission electron microscopy tem, and particle size analyzer. Stability determination of nanofluid suspension based on. Lees disc apparatus comprises of a brass disc resting on another slab of. Once the steam is flowing well and thermometer t1 has started to rise significantly, adjust the rate of water flow. Besides the application of newtons law of cooling one can also measure the thermal conductivity by using simple calorimetric method which is as follows. The thermal conductivity of bulk materials can be engineered by various means such as the use of composite materials 1 or metamaterials 2. The answer is not complicated, lees disk is an apparatus consist of metallic cylindrical chamber and a disk. What is thermal conductivity of a bad conductor by lees disc.
Lees disc experiment for thermal conductivities physics. Thermal conductivity is the property of a material. Anna university lab experiment lees disc method experiment physics practical. Engineering the thermal conductivity along an individual. Oct 09, 2015 click here to build your own lees disc. It depends on the state of the material, which is a function of the chemical composition and physical structure. Lee s disc apparatus comprises of a brass disc resting on another slab of the same dimension with special heating coil. How to make a lees disk for measuring thermal conductivity. As a result, equation 5 is a better alternative for determination of tc of metals. The thermal conductivity of bad conductor is given by. In this work, the thermal conductivity of kosso and mahogany wood were determined following the device of lees disk. Experiment t1 measuring the thermal conductivity of copper objectives. Thermal conductivity of a bad conductor using lee disc electrical.
Procedure examine the demonstration model of the modified searles apparatus which is on display in the laboratory. The purpose of this experimental study is to evaluate the effects of particle species, surface charge, concentration, preparation technique, and base fluid on thermal transport capability of nanopa. We present experimental results of the thermal conductivity of several nanofluids prepared by dispersing nanoparticles of sio2 and cuo in water and ethylene glycol at various concentrations up to. The thermal conductivity of building materials is an important property for engineering and for the analysis of insulating materials. The modified lee s disc setup is equipped with various types of electrical device and probes. The measurements have been performed by the multicurrent hotwire technique. You know from experience that heat flows from hot to cold. What is thermal conductivity of a bad conductor by lees disc method.
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