To study the thermal conductivity of a substance, two groups of methods are used: stationary and non-stationary.
The theory of stationary methods is simpler and more fully developed. But non-stationary methods, in principle, in addition to the thermal conductivity coefficient, allow obtaining information about the thermal diffusivity and heat capacity. Therefore, in Lately Much attention is paid to the development of non-stationary methods for determining the thermophysical properties of substances.
Here, some stationary methods for determining the thermal conductivity of substances are considered.
but) Flat layer method. With a one-dimensional heat flow through a flat layer, the thermal conductivity coefficient is determined by the formula
where d- thickness, T 1 and T 2 - temperatures of the "hot" and "cold" surface of the sample.
To study thermal conductivity by this method, it is necessary to create a heat flux close to one-dimensional.
Usually temperatures are measured not on the surface of the sample, but at some distance from them (see Fig. 2.), therefore, it is necessary to introduce corrections into the measured temperature difference for the temperature difference in the layer of the heater and cooler, to minimize the thermal resistance of the contacts.
When studying liquids, to eliminate the phenomenon of convection, the temperature gradient must be directed along the gravitational field (down).
Rice. 2. Scheme of flat layer methods for measuring thermal conductivity.
1 – test sample; 2 - heater; 3 - refrigerator; 4, 5 - insulating rings; 6 – security heaters; 7 - thermocouples; 8, 9 - differential thermocouples.
b) Jaeger's method. The method is based on solving a one-dimensional heat equation describing the propagation of heat along a rod heated by an electric current. The difficulty of using this method lies in the impossibility of creating strict adiabatic conditions on the outer surface of the sample, which violates the one-dimensionality of the heat flux.
The calculation formula looks like:
(14)
where s- electrical conductivity of the test sample, U is the voltage drop between the extreme points at the ends of the rod, DT is the temperature difference between the middle of the rod and the point at the end of the rod.
Rice. 3. Scheme of the Jaeger method.
1 - electric furnace; 2 - sample; 3 - trunnions for fastening the sample; T 1 ¸ T 6 - thermocouple termination points.
This method is used in the study of electrically conductive materials.
in) Cylindrical layer method. The investigated liquid (bulk material fills a cylindrical layer formed by two coaxial cylinders. One of the cylinders, most often internal, is a heater (Fig. 4).
Fig. 4. Scheme of the cylindrical layer method
1 - inner cylinder; 2 - main heater; 3 - layer of the test substance; 4 - outer cylinder; 5 - thermocouples; 6 - security cylinders; 7 - additional heaters; 8 - body.
Let us consider in more detail the stationary process of heat conduction in a cylindrical wall, the temperature of the outer and inner surfaces of which is maintained constant and equal to T 1 and T 2 (in our case, this is the layer of the substance under study 5). Let us determine the heat flux through the wall under the condition that the inner diameter of the cylindrical wall is d 1 = 2r 1, and the outer diameter is d 2 = 2r 2 , l = const, and heat propagates only in the radial direction.
To solve the problem, we use equation (12). In cylindrical coordinates, when 
; equation (12), according to (10), takes vit:
. (15)
Let's introduce the notation dT/dr= 0, we get
After integrating and potentiating this expression, passing to the original variables, we get:
. (16)
As can be seen from this equation, the dependence T=f(r) is logarithmic.
The integration constants C 1 and C 2 can be determined by substituting the boundary conditions into this equation:
at r \u003d r 1 T \u003d T 1 And T 1 \u003d C 1 ln r1+C2,
at r=r2 T=T2 And T 2 \u003d C 1 ln r2+C2.
The solution of these equations with respect to FROM 1 and From 2 gives:
; 
Substituting these expressions for From 1 And From 2 into equation (1b), we get
(17)
heat flow through the area of a cylindrical surface of radius r and length is determined using the Fourier law (5)
.
After substitution, we get
. (18)
Thermal conductivity coefficient l at known values Q, T 1 , T 2 , d 1 , d 2 , calculated by the formula
. (19)
To suppress convection (in the case of a liquid), the cylindrical layer must have a small thickness, typically fractions of a millimeter.
Reduction of end losses in the cylindrical layer method is achieved by increasing the ratio / d and security heaters.
G) hot wire method. In this method, the relation / d increases by decreasing d. The inner cylinder is replaced by a thin wire, which was both a heater and a resistance thermometer (Fig. 5). As a result of the relative simplicity of design and detailed development of the theory, the heated wire method has become one of the most advanced and accurate. In the practice of experimental studies of the thermal conductivity of liquids and gases, he occupies a leading place.
Rice. 5. Scheme of the measuring cell made according to the heated wire method. 1 - measuring wire, 2 - tube, 3 - test substance, 4 - current leads, 5 - potential taps, 6 - external thermometer.
Under the condition that the entire heat flux from section AB propagates radially and the temperature difference T 1 - T 2 is not large, so that l = const can be considered within these limits, the thermal conductivity of the substance is determined by the formula
, (20)
where Q AB = T×U AB is the power dissipated on the wire.
e) ball method. It finds application in the practice of studying the thermal conductivity of liquids and bulk materials. The substance under study is given the shape of a spherical layer, which makes it possible, in principle, to exclude uncontrolled heat losses. Technically, this method is rather complicated.
Whatever the scale of construction, the first step is to develop a project. The drawings reflect not only the geometry of the structure, but also the calculation of the main thermal characteristics. To do this, you need to know the thermal conductivity building materials. The main goal of construction is to build durable structures, durable structures that are comfortable without excessive heating costs. In this regard, it is extremely important to know the thermal conductivity coefficients of materials.
Brick has the best thermal conductivity
Characteristics of the indicator
The term thermal conductivity refers to the transfer of thermal energy from hotter objects to cooler ones. The exchange continues until temperature equilibrium is reached.
Heat transfer is determined by the length of time during which the temperature in the premises is in accordance with the ambient temperature. The smaller this interval, the greater the thermal conductivity of the building material.
To characterize the conductivity of heat, the concept of the thermal conductivity coefficient is used, which shows how much heat passes through such and such a surface area in such and such time. The higher this figure, the greater the heat transfer, and the building cools down much faster. Thus, when erecting structures, it is recommended to use building materials with minimal heat conductivity.
In this video you will learn about the thermal conductivity of building materials:
How to determine heat loss
The main elements of the building through which heat escapes:
- doors (5-20%);
- gender (10-20%);
- roof (15-25%);
- walls (15-35%);
- windows (5-15%).
The level of heat loss is determined using a thermal imager. Red indicates the most difficult areas, yellow and green indicate less heat loss. Zones with the least losses are highlighted in blue. The value of thermal conductivity is determined in the laboratory, and the material is issued a quality certificate.
The value of heat conductivity depends on the following parameters:
- Porosity. The pores indicate the heterogeneity of the structure. When heat passes through them, cooling will be minimal.
- Humidity. A high level of humidity provokes the displacement of dry air by liquid droplets from the pores, due to which the value increases many times over.
- Density. Higher density promotes more active interaction of particles. As a result, heat transfer and temperature balancing proceeds faster.
Coefficient of thermal conductivity
In the house, heat loss is inevitable, and they occur when the temperature outside the window is lower than in the rooms. The intensity is a variable and depends on many factors, the main of which are the following:
- Surface area involved in heat transfer.
- An indicator of thermal conductivity of building materials and building elements.
- temperature difference.
The Greek letter λ is used to designate the thermal conductivity of building materials. The unit of measurement is W/(m×°C). The calculation is made for 1 m² of a meter-thick wall. A temperature difference of 1°C is assumed here.
Case Study
Conventionally, materials are divided into heat-insulating and structural. The latter have the highest thermal conductivity; walls, ceilings, and other fences are built from them. According to the table of materials, when building reinforced concrete walls to ensure low heat exchange with environment their thickness should be approximately 6 m. But then the building will be bulky and expensive.
In the event of an incorrect calculation of thermal conductivity during the design, the residents of the future house will be content with only 10% of the heat from energy sources. Therefore, houses made of standard building materials are recommended to be insulated additionally.
When performing the correct waterproofing of the insulation, high humidity does not affect the quality of the thermal insulation, and the resistance of the building to heat transfer will become much higher.
Most best option- use a heater
The most common option is a combination of a supporting structure made of high-strength materials with additional thermal insulation. For example:
- Frame house. Insulation is placed between the posts. Sometimes, with a slight decrease in heat transfer, additional insulation is required outside the main frame.
- Construction of standard materials. When the walls are brick or cinder block, insulation is done from the outside.
Building materials for exterior walls
The walls today are being built from different materials, however, the most popular are: wood, brick and building blocks. The main difference is the density and heat conductivity of building materials. Comparative analysis allows you to find the golden mean in the ratio between these parameters. The greater the density, the greater the bearing capacity of the material, and hence the entire structure. But the thermal resistance becomes smaller, that is, energy costs increase. Usually at lower density there is porosity.
Thermal conductivity coefficient and its density.
Wall insulation
Heaters are used when there is not enough thermal resistance of the outer walls. Usually, to create a comfortable microclimate in the premises, a thickness of 5-10 cm is sufficient.
The value of the coefficient λ is given in the following table.
Thermal conductivity measures the ability of a material to conduct heat through itself. It strongly depends on the composition and structure. Dense materials such as metals and stone are good heat conductors, while low density materials such as gas and porous insulation are poor conductors.
Thermal conductivity is the most important thermophysical characteristic of materials. It must be taken into account when designing heating devices, choosing the thickness of protective coatings, and taking into account heat losses. If an appropriate reference book is not at hand or available, and the composition of the material is not exactly known, its thermal conductivity must be calculated or measured experimentally.
Components of thermal conductivity of materials
Thermal conductivity characterizes the process of heat transfer in a homogeneous body with certain overall dimensions. Therefore, the initial parameters for measurement are:
- Area in the direction perpendicular to the direction of heat flow.
- The time during which the transfer of heat energy occurs.
- The temperature difference between the separate, most distant parts of a part or test specimen.
- Heat source power.
To maintain the maximum accuracy of the results, it is required to create stationary (settled in time) heat transfer conditions. In this case, the time factor can be neglected.
Thermal conductivity can be determined in two ways - absolute and relative.
Absolute method for assessing thermal conductivity
In this case, the direct value of the heat flux is determined, which is directed to the sample under study. Most often, the sample is taken as a rod or plate, although in some cases (for example, when determining the thermal conductivity of coaxially placed elements), it may look like a hollow cylinder. The disadvantage of lamellar specimens is the need for strict plane-parallelism of opposite surfaces.
Therefore, for metals characterized by high thermal conductivity, a sample in the form of a rod is more often taken.
The essence of the measurements is as follows. On opposite surfaces, constant temperatures are maintained, arising from a heat source, which is located strictly perpendicular to one of the surfaces of the sample.
In this case, the desired thermal conductivity parameter λ will be
λ=(Q*d)/F(T2-T1), W/m∙K, where:
Q is the heat flow power;
d is the sample thickness;
F is the sample area affected by the heat flux;
T1 and T2 are the temperatures on the sample surfaces.
Since the heat flux power for electric heaters can be expressed in terms of their power UI, and temperature sensors connected to the sample can be used to measure temperature, it will not be difficult to calculate the thermal conductivity index λ.
In order to eliminate unproductive heat loss and improve the accuracy of the method, the sample and heater assembly should be placed in an effective heat-insulating volume, for example, in a Dewar vessel.
Relative method for determining thermal conductivity
It is possible to exclude from consideration the heat flux power factor if one of the comparative evaluation methods is used. For this purpose, a reference sample is placed between the rod, the thermal conductivity of which is to be determined, and the heat source, the thermal conductivity of the material of which λ 3 is known. To eliminate measurement errors, the samples are tightly pressed against each other. The opposite end of the measured sample is immersed in a cooling bath, after which two thermocouples are connected to both rods.
Thermal conductivity is calculated from the expression
λ=λ 3 (d(T1 3 -T2 3)/d 3 (T1-T2)), where:
d is the distance between thermocouples in the test sample;
d 3 is the distance between thermocouples in the reference sample;
T1 3 and T2 3 - readings of thermocouples installed in the reference sample;
T1 and T2 are readings of thermocouples installed in the test sample.
The thermal conductivity can also be determined from the known electrical conductivity γ of the sample material. For this, a wire conductor is taken as the test sample, at the ends of which a constant temperature is maintained by any means. A direct electric current of force I is passed through the conductor, and the terminal contact should approach ideal.
Upon reaching the stationary thermal state, the temperature maximum T max will be located in the middle of the sample, with the minimum values of T1 and T2 at its ends. By measuring the potential difference U between the extreme points of the sample, the value of thermal conductivity can be determined from the dependence
The accuracy of thermal conductivity estimation increases with the length of the test sample, as well as with the increase in the current that is passed through it.
Relative methods for measuring thermal conductivity are more accurate than absolute ones, and are more convenient in practical application, however, require a significant investment of time to perform measurements. This is due to the duration of the establishment of a stationary thermal state in the sample, the thermal conductivity of which is determined.
during their thermal motion. In liquids and solids - dielectrics - heat transfer is carried out by direct transfer of the thermal motion of molecules and atoms to neighboring particles of matter. In gaseous bodies, the propagation of heat by thermal conduction occurs due to the exchange of energy during the collision of molecules with different speeds of thermal motion. In metals, thermal conductivity is carried out mainly due to the movement of free electrons.
The main term of thermal conductivity includes a number of mathematical concepts, the definitions of which, it is advisable to recall and explain.
temperature field- these are sets of temperature values \u200b\u200bin all points of the body at a given moment in time. Mathematically, it is described as t = f(x, y, z, t). Distinguish stationary temperature field when the temperature at all points of the body does not depend on time (does not change over time), and non-stationary temperature field. In addition, if the temperature changes only along one or two spatial coordinates, then the temperature field is called, respectively, one- or two-dimensional.
Isothermal surface is the locus of points that have the same temperature.
temperature gradient — grad t there is a vector directed along the normal to the isothermal surface and numerically equal to the derivative of the temperature in this direction.
According to the basic law of heat conduction - the law Fourier(1822), the heat flux density vector transmitted by thermal conduction is proportional to the temperature gradient:
q = - λ grad t, (3)
where λ - coefficient of thermal conductivity of the substance; its unit of measure Tue/(m K).
The minus sign in equation (3) indicates that the vector q directed opposite to the vector grad t, i.e. towards the lowest temperature.
heat flow δQ through an arbitrarily oriented elementary area dF is equal to the scalar product of the vector q to the elementary area vector dF, and the total heat flux Q across the entire surface F is determined by integrating this product over the surface F:
COEFFICIENT OF THERMAL CONDUCTIVITY
Coefficient of thermal conductivity λ in law Fourier(3) characterizes the ability of a given substance to conduct heat. The values of the thermal conductivity coefficients are given in reference books on the thermophysical properties of substances. Numerically, the thermal conductivity coefficient λ = q/ grad t equal to the heat flux density q with temperature gradient grad t = 1 K/m. The lightest gas, hydrogen, has the highest thermal conductivity. At room conditions thermal conductivity of hydrogen λ = 0,2 Tue/(m K). Heavier gases have less thermal conductivity - air λ = 0,025 Tue/(m K), in carbon dioxide λ = 0,02 Tue/(m K).
Pure silver and copper have the highest thermal conductivity: λ = 400 Tue/(m K). For carbon steels λ = 50 Tue/(m K). In liquids, the thermal conductivity is usually less than 1 Tue/(m K). Water is one of the best liquid conductors of heat, for it λ = 0,6 Tue/(m K).
The thermal conductivity coefficient of non-metallic solid materials is usually below 10 Tue/(m K).
Porous materials - cork, various fibrous fillers such as organic wool - have the lowest thermal conductivity coefficients λ <0,25 Tue/(m K), approaching at a low packing density to the coefficient of thermal conductivity of the air filling the pores.
Temperature, pressure, and, for porous materials, humidity can also have a significant impact on the thermal conductivity. Reference books always give the conditions under which the thermal conductivity of a given substance was determined, and for other conditions these data cannot be used. Value ranges λ for various materials are shown in fig. one.
Fig.1. Intervals of values of thermal conductivity coefficients of various substances.
Heat transfer by thermal conduction
Homogeneous flat wall.
The simplest and very common problem solved by the theory of heat transfer is to determine the density of the heat flux transmitted through a flat wall with a thickness δ , on the surfaces of which temperatures are maintained tw1 And t w2 .(Fig. 2). The temperature changes only along the thickness of the plate - one coordinate X. Such problems are called one-dimensional, their solutions are the simplest, and in this course we will restrict ourselves to consideration of only one-dimensional problems.
Considering that for the one-numbered case:
grad t = dt/dх, (5)
and using the basic law of heat conduction (2), we obtain a differential equation for stationary heat conduction for a flat wall:
In stationary conditions, when energy is not spent on heating, the heat flux density q unchanged in wall thickness. In most practical problems, it is approximately assumed that the thermal conductivity coefficient λ does not depend on temperature and is the same throughout the entire thickness of the wall. Meaning λ found in reference books at a temperature of:
average between the temperatures of the wall surfaces. (The calculation error in this case is usually less than the error of the initial data and tabular values, and with a linear dependence of the thermal conductivity coefficient on temperature: λ = a + bt exact calculation formula for q does not differ from the approximate one). At λ = const:
(7)
those. temperature dependence t from the coordinate X linear (Fig. 2).
Fig.2. Stationary temperature distribution over the thickness of a flat wall.
Dividing the variables in equation (7) and integrating over t from tw1 before tw2 and by X from 0 to δ :
, (8)
we obtain the dependence for calculating the heat flux density:
, (9)
or heat flow power (heat flow):
(10)
Therefore, the amount of heat transferred through 1 m 2 walls, directly proportional to the coefficient of thermal conductivity λ and the temperature difference of the outer surfaces of the wall ( t w1 - t w2) and inversely proportional to the wall thickness δ . The total amount of heat through the wall area F also in proportion to this area.
The resulting simplest formula (10) is very widely used in thermal calculations. This formula not only calculates the heat flux density through flat walls, but also makes estimates for more complex cases, simplistically replacing walls of complex configuration with a flat wall in the calculations. Sometimes, already on the basis of an assessment, one or another option is rejected without further expenditure of time for its detailed study.
Body temperature at a point X is determined by the formula:
t x = t w1 - (t w1 - t w2) × (x × d)
Attitude λF/δ is called the thermal conductivity of the wall, and the reciprocal δ/λF thermal or thermal resistance of the wall and is denoted Rλ. Using the concept of thermal resistance, the formula for calculating the heat flux can be represented as:
Dependence (11) is similar to the law Ohma in electrical engineering (the strength of the electric current is equal to the potential difference divided by the electrical resistance of the conductor through which the current flows).
Very often, thermal resistance is called the value δ / λ, which is equal to the thermal resistance of a flat wall with an area of 1 m 2.
Calculation examples.
Example 1. Determine the heat flux through the concrete wall of a building with a thickness of 200 mm, height H = 2,5 m and length 2 m if the temperatures on its surfaces are: t с1\u003d 20 0 C, t с2\u003d - 10 0 С, and the coefficient of thermal conductivity λ =1 Tue/(m K):
= 750 Tue.
Example 2. Determine the thermal conductivity of the wall material with a thickness of 50 mm, if the heat flux density through it q = 100 Tue/m 2, and the temperature difference on the surfaces Δt = 20 0 C.
Tue/(m K).
Multilayer wall.
Formula (10) can also be used to calculate the heat flux through a wall consisting of several ( n) layers of dissimilar materials closely adjacent to each other (Fig. 3), for example, a cylinder head, gasket and cylinder block made of different materials, etc.
Fig.3. Temperature distribution over the thickness of a multilayer flat wall.
The thermal resistance of such a wall is equal to the sum of the thermal resistances of the individual layers:
(12)
In formula (12), it is necessary to substitute the temperature difference at those points (surfaces), between which all the summed thermal resistances are “included”, i.e. in this case: tw1 And w(n+1):
, (13)
where i- layer number.
In the stationary mode, the specific heat flux through the multilayer wall is constant and the same for all layers. From (13) follows:
. (14)
It follows from equation (14) that the total thermal resistance of a multilayer wall is equal to the sum of the resistances of each layer.
Formula (13) can be easily obtained by writing the temperature difference according to formula (10) for each of P layers of a multilayer wall and adding up all P expressions, taking into account the fact that in all layers Q has the same meaning. When added, all intermediate temperatures will decrease.
The temperature distribution within each layer is linear, however, in different layers, the slope of the temperature dependence is different, since according to formula (7) ( dt/dx)i = - q/λ i. The density of the heat flux passing through the entire layer is the same in the stationary mode, and the thermal conductivity of the layers is different, therefore, the temperature changes more sharply in layers with lower thermal conductivity. So, in the example in Fig. 4, the material of the second layer (for example, gaskets) has the lowest thermal conductivity, and the third layer has the highest.
Having calculated the heat flux through a multilayer wall, one can determine the temperature drop in each layer using relation (10) and find the temperatures at the boundaries of all layers. This is very important when using materials with a limited allowable temperature as heat insulators.
The temperature of the layers is determined by the following formula:
t sl1 \u003d t c t1 - q × (d 1 × l 1 -1)
t sl2 \u003d t c l1 - q × (d 2 × l 2 -1)
Contact thermal resistance. When deriving formulas for a multilayer wall, it was assumed that the layers closely adjoin each other, and due to good contact, the contacting surfaces of different layers have the same temperature. Ideally tight contact between the individual layers of a multilayer wall is obtained if one of the layers is applied to another layer in a liquid state or in the form of a fluid solution. Solid bodies touch each other only at the tops of the roughness profiles (Fig. 4).
The contact area of the vertices is negligible, and the entire heat flow goes through the air gap ( h). This creates additional (contact) thermal resistance. R to. Thermal contact resistances can be determined independently using the appropriate empirical dependencies or experimentally. For example, a gap thermal resistance of 0.03 mm approximately equivalent to the thermal resistance of a layer of steel with a thickness of about 30 mm.
Fig.4. Image of contacts of two rough surfaces.
Methods for reducing thermal contact resistance. The total thermal resistance of the contact is determined by the cleanliness of processing, the load, the thermal conductivity of the medium, the thermal conductivity coefficients of the materials of the contacting parts, and other factors.
The greatest efficiency in reducing thermal resistance is provided by the introduction into the contact zone of a medium with a thermal conductivity close to that of the metal.
There are the following possibilities for filling the contact zone with substances:
Use of gaskets made of soft metals;
Introduction to the contact zone of a powdered substance with good thermal conductivity;
Introduction to the zone of a viscous substance with good thermal conductivity;
Filling the space between the protrusions of roughness with liquid metal.
The best results were obtained when the contact zone was filled with molten tin. In this case, the thermal resistance of the contact practically becomes equal to zero.
Cylindrical wall.
Very often, coolants move through pipes (cylinders), and it is required to calculate the heat flux transmitted through the cylindrical wall of the pipe (cylinder). The problem of heat transfer through a cylindrical wall (with known and constant temperatures on the inner and outer surfaces) is also one-dimensional if considered in cylindrical coordinates (Fig. 4).
The temperature changes only along the radius, and along the length of the pipe l and along its perimeter remains unchanged.
In this case, the heat flow equation has the form:
. (15)
Dependence (15) shows that the amount of heat transferred through the cylinder wall is directly proportional to the thermal conductivity coefficient λ , pipe length l and temperature difference ( t w1 - t w2) and inversely proportional to the natural logarithm of the ratio of the outer diameter of the cylinder d2 to its inner diameter d1.
Rice. 4. Change in temperature across the thickness of a single-layer cylindrical wall.
At λ = const temperature distribution by radius r of a single-layer cylindrical wall obeys a logarithmic law (Fig. 4).
Example. How many times are heat losses reduced through the wall of the building, if between two layers of bricks with a thickness of 250 mm install a foam pad 50 thick mm. The thermal conductivity coefficients are respectively equal: λ kirp . = 0,5 Tue/(m K); λ pen. . = 0,05 Tue/(m K).
In accordance with the requirements of Federal Law No. 261-FZ "On Energy Saving", the requirements for the thermal conductivity of building and thermal insulation materials in Russia have been tightened. Today, the measurement of thermal conductivity is one of the mandatory points when deciding whether to use a material as a heat insulator.
Why is it necessary to measure thermal conductivity in construction?
The control of thermal conductivity of building and thermal insulation materials is carried out at all stages of their certification and production in laboratory conditions, when materials are exposed to various factors that affect their performance properties. There are several common methods for measuring thermal conductivity. For accurate laboratory testing of materials with low thermal conductivity (below 0.04 - 0.05 W / m * K), it is recommended to use instruments using the stationary heat flow method. Their use is regulated by GOST 7076.
The company "Interpribor" offers a thermal conductivity meter, the price of which compares favorably with those available on the market and meets all modern requirements. It is intended for laboratory quality control of building and heat-insulating materials.
Advantages of the ITS-1 thermal conductivity meter
Thermal conductivity meter ITS-1 has an original monoblock design and is characterized by the following advantages:
- automatic measurement cycle;
- high-precision measuring path, which allows to stabilize the temperatures of the refrigerator and heater;
- the possibility of calibrating the device for certain types of materials under study, which further increases the accuracy of the results;
- express evaluation of the result in the process of performing measurements;
- optimized "hot" security zone;
- informative graphical display that simplifies the control and analysis of measurement results.
ITS-1 is supplied in the only basic modification, which, at the request of the client, can be supplemented with control samples (plexiglass and foam plastic), a box for bulk materials and a protective case for storing and transporting the device.
