SU1509702A1 - Device for measuring thermo-physicald characteristics of loose materials - Google Patents

Abstract

The invention relates to physical measurements, namely to a device for determining the thermophysical characteristics of bulk materials. The purpose of the invention is to improve the accuracy of determination by ensuring a homogeneous structure of the samples. On both surfaces of the double-sided heater, grooves are made, converging in the form of rays to the external diameter of the heater in its upper part and interconnected by holes. 3 il.

Description

The invention relates to the field of heat engineering measurements and is intended for the integrated measurement of the thermophysical characteristics (specific heat capacity, thermal conductivity and thermal diffusivity) of bulk materials.

The purpose of the invention is to improve the accuracy of measurement of thermal characteristics by providing a homogeneous density of samples.

FIG. 1 shows a front projection device 13; in fig. 2- tr, a cut on the flat heater; in FIG. 3, section A-A in FIG. 2. A device for measuring thermal and physical characteristics consists of a segment of a cylindrical tube 1 made of thermal insulation material, into which two thermostatic chambers 2 are placed in the form of

pistons. These chambers with the help of brackets are fixed on the rods 3, which pass through the caps 4, covering the ends of the 5th pipe. In the middle of the cylindrical tube in a plane perpendicular to its axis, a continuous cut is made for the heater thickness in the upper part, here. There is a flat heater 6, which is a thin frame made of fiberglass 7, on which the constantan is wound on both sides with a step of 1 mm - manganin wire 8d. The ends of the heating winding, as well as thermocouples, are led out onto a special spike 9. On both surfaces of the heater cage, grooves 10 are made, converging in the form of beams to its spike. The grooves of both planes are interconnected by a series of holes.

At the top of the sample holder on either side of the transverse path

Oh j

ABOUT

1C

3,150

There is a slit groove that allows the heater to move along the axis of the holder. The material to be studied (measured) is placed in both measuring chambers. Each of the thermostatically controlled chambers 2 has two fittings I1 on the outside, through which rubber hoses are brought in and drained from the rubber hoses. thermostat (not shown). The thermostated chambers are moved with screws 3 with the help of 12 "handles. The entire sample holder design is fixed on a stand-base 13 with a clamp and straps with the possibility of rotation around the mounting axis within 180 °. ,; mounted on the outer side of thermostatically controlled chambers. Cold and hot junctions of miniature thermocouples are fixed on the inner walls of thermostatically controlled chambers and on both planes of the heater.

The device works as follows

A flat heater 6 is inserted into the slot of the cylindrical tube 1, which is wired to the measuring equipment and a stabilized voltage source (not shown). The pipe 1 is rotated to a vertical position, a peat weight of a certain weight is fixed into it and the thermostatted chamber 2 is inserted together with the lid A o After the lid 4 is fixed by rotation, the chamber is brought into contact with the preformed surface of the material. The tube holder 1 is rotated 180. Similar operations are performed to place a sample of material into the second measuring chamber. Alignment bars 14 equalize size 1 for both measurement chambers. Any change of this size is made by simultaneous rotation of both handles with control by reference bars,

which provides the same effort

acting on the heater 6,

Sample size

are selected from the provision of

requirements

1 / R 1/4,

where R is the radius of the pipe holder sample.

The measurement of the thermophysical characteristics placed in the sample holder of the material is carried out by methods of stationary and regular thermal conditions according to known methods,

Using the proposed device, the following characteristics are measured:

coefficient of thermal conductivity by the formula

-X

W1

2G & tGg

where W is the power of the heater;

1 - thickness (height) of the sample

peat;

F is the area of the heater (sample);

  the temperature difference on the two surfaces of the sample in the steady state, the thermal diffusivity Q by the formula

. , R, 2 and 4t (.5;),

where R is the radius of the sample material; m is the temperature measurement rate; specific heat capacity С „and is calculated by the two previous characteristics

- p - material density at the moment

measurements p 4M / 1t D l M - mass, D - diameter and 1 - thickness (height) of the material sample „

All parameters in the equations are determined in the measurement experiment.

The proposed device is designed to operate in the temperature mode O - 90 ° C. Using a two-sided heater during measurements, a controlled pulse is given a heat pulse, which provides an increase in the temperature of the controlled sample by 4-6 C above the system temperature set using a thermostat.

The execution on the end surfaces of the heater of the shallow grooves, converging in the form of rays to the lateral surface of the heater in its upper part and interconnected by holes, allows air that accumulates at the heater when compressed controlled samples of bulk materials go up to longitudinal groove of the holder beyond it. Removing the air during compaction helps to obtain a more uniform density of the sample structure, which improves the measurement accuracy.

For inquiries

A device for measuring the heat and physical characteristics of loose materials, containing the holder, a sample in the form of a smooth-walled cylindrical 5097026

This tube, in the center of which is a flat two-sided heater, is two thermostated lacamers, 5 axially displaced with the possibility of axial movement on both sides of the heater, and temperature sensors in the center of the heater, differing from the fact that, in order to increase 10 accuracy thermophysical characteristics by providing a uniform density of the structure of the samples on both end surfaces

Heaters are made grooves connected to each other by holes and converging in the form of rays to the side surface of the heater in its upper part.

one

FIG. 2

Thermocouple layers

Fi.Z

Claims (1)

SUMMARY OF THE INVENTION Device for measuring heat | physical characteristics of bulk materials, containing a holder, a sample in the form of a smooth-walled cylindrical tube, in the center of which a flat double-sided heater is installed, two thermostatically controlled chambers placed with the possibility of axial movement on both sides of the heater, and temperature sensors in the center of the heater, characterized in that, in order to improve the accuracy of measuring the thermophysical characteristics by ensuring a uniform density structure of the samples, on both end surfaces of the heater The grooves are interconnected by holes and converging in the form of beams to the side surface of the heater in its upper part. fie. 2