SU1352331A1 - Device for determining thermal-physical characteristics of soils in field conditions - Google Patents

Abstract

The invention relates to the field of determining the thermophysical characteristics of soils in the field. The purpose of the invention is to improve the accuracy and reduce the thermal inertia of the device. The temperature sensor 1 is made in the form of a tube, inside which a constant power heater is placed. To determine the thermal characteristics, the temperature sensor 1 is introduced into the soil and held for about a minute, then the toggle switch 5 turns on the heater and the digital ohmmeter 3 measures the resistance of the temperature sensor 1 at two points in time after heating. The power of the heater is calculated from the reading of ammeter 7 and voltmeter 8 using the above formula. Then, the thermal conductivity, thermal diffusivity, and volumetric heat capacity are given from the above ratios, 4 Il. e (/)

Description

ten

11352331

The invention relates to the determination of the thermophysical characteristics of soils under field conditions (thermal conductivity, thermal diffusivity and heat capacity).

The purpose of the invention is to increase the accuracy and reduce the thermal inertia of the device.

Figure 1 shows the layout of the device; Fig. 2 shows a temperature sensor with a constant motor heater; on fig.Z - thermogram of the device; fig, / - thermogram of the prototype.

A device for determining the thermal and physical characteristics of soil in field conditions consists (see FIG. 1). from temperature sensor i, pins 2 of which are connected to a digital ohmmeter 3, a constant power heater, pins 4 of which are connected to a toggle switch 5, battery 6, ammeter 7 and voltmeter 8. Temperature sensor 1 (see, figure 2} is made of high resistance silicon in the form of a tube 9, inside of which is placed on: a constant power heater consisting of a ceramic capillary 10, on the surface of which a constant heater 11. is bifilically wound. The tube 9 is covered with a thin insulating layer of a dielectric, filled with a heat-exchanging gas and a cup replen to the ebonite head 12.

To determine the thermophysical characteristics, a temperature sensor 1 is introduced into the soil and held for about one minute to take on a tempo. X

with

,, and t

4 t-l (t, -t,)

hk,

temperatures at times

€.

 g 1 is the length of the probe;

15 К ,, К, are the constant values determined by the size of the temperature sensor, determined from the ratios

20

(F)

Kg

, 0-3

5 R

- g

25

Where

g - R X 30

inner radius; external radius of the temperature sensor;

constant value, determined depending on the temperatures t), tj from the formula In 2

exp

T7t5ti t7

- one

35

To build a thermogram after 10 s (t, after turning on a constantan heater 11, a soil routine is recorded every 3 seconds, then a toggle switch 5 turns on a digital ohmmeter 3. read a constantan heater 11 as an example of a specific and digital ohmmeter 3 (in advance. performance was made by device

measured by temperature) the resistance of the temperature sensor 1 at two points in time is measured

G. and

 r (where

10 and 60 s) after heating,

stationary temperature stroke; C, - end of hospital 0 - start

and t.

nano temperature course; progress is experimentally.

The power of the constantan heater 11 is calculated from the reading of ammeter 7 and voltmeter 8 using the formula W UI. Then, the obtained experimental values, t i g and W are substituted into the formulas and calculated -. thermal conductivity (.), temperature conductivity (a) and volumetric heat capacity, (c) of the following relations:

. X

ten

with

4 t-l (t, -t,)

hk,

,, and t

temperatures at times

€.

 g 1 is the length of the probe;

K ,, K, are constant values determined by the size of the temperature sensor, determined from the ratios

20

(F)

Kg

, 0-3

5 R

- g

Where

g - R X

inner radius; external radius of the temperature sensor;

constant value, determined depending on the temperatures t), tj from the formula In 2

exp

T7t5ti t7

- one

A tool for determining the thermophysical characteristics of soils in field conditions, containing a temperature sensor made of high-resistance silicon in the form of a tube 50 mm long, with an outer diameter of 4 mm, with an inner diameter of 2.5 mm, and a ceramic capillary with an outer diameter 2 mm through which the bottom output of the temperature sensor is led to its head. A constantan wire with a diameter of 0.05 mm is wound on the surface of the ceramic capillary. The sensor is filled with heat exchange gas (in our case, helium), covered with a thin insulating layer and attached to the ebonite head. The outputs of the constantan heater are also output to the ebony sensor head.

The temperature sensor leads are connected to a digital ohmmeter, which uses a universal 1-digit voltmeter V7-35, and the outputs of a constant-power heater are connected via a toggle switch to a battery, a milliammeter M42I01 (0-100 mA), and a M42100 voltmeter (0-30 V) .

Claims (1)

Invention Formula A device for determining the heat- 15 physical characteristics of the soil in a field of constant power. conditions, containing data points, a constant heater, sequentially connecting a toggle switch, a battery and a meter, and in parallel — a voltage that increases accuracy and mind thermal inertia, a digital ohmmeter is inserted, connected to the terminals of the temperature sensor in the form of a hermetic t with a pointed end of high silicon, filled with heat and gas, inside which is placed T.N 9 L7 // 3015 V phi5.2 About Sh th 30 40 50 60 70 t sen FIG. water of a constant power. A temperature sensor, a constant power heater, a toggle switch, a battery and an ammeter connected in series with it, and a voltmeter in parallel, which is due to the fact that, in order to improve accuracy and reduce thermal inertia, a digital an ohmmeter connected to the terminals of a temperature sensor, made in the form of a sealed tube with a pointed end made of high-resistance silicon filled with heat-exchange gas, inside which is placed a heated, 5,296.0.0 v. 5 297.0 296.5 296.0 29S, S 295  About 20 40 do VO 70O PO 140 760 180 G sep FIG. four Editor A.Dolinich Compiled by L. Bal Nina Tehred M.Morg.ental Proofreader S.Shekmar Order 5558/41 Circulation 776 Subscription VNISh State Committee of the USSR for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab, 4/5 Production and printing company, Uzhgorod, st. Project, 4