RU72062U1 - HEAT FLOW DENSITY SENSOR - Google Patents

Abstract

1. A heat flux density sensor containing a carrier base and a thermocouple battery, characterized in that a concentrator is inserted in it, located on the central part of the carrier base, which is made in the form of a silicon profiled membrane on which the indicated thermocouple battery made in the form of polysilicon aluminum mesostructures and coated with a layer of protective dielectric oxide.

Description

The proposed utility model relates to the field of measurement technology and can be used in devices for determining the density of the heat flux.

A known heat flux density sensor company Rdf (http://www.rdfcorp.com/products/hflux/hfs-c_01.shtml), containing a carrier base that allows you to convert the heat flux density to a temperature difference, as well as a thermocouple battery as a thermocouple temperature difference in an electrical signal.

However, this sensor uses metal thermocouples with a relatively small coefficient of thermoEMF, and this device also has low thermal resistance, which leads to a decrease in the sensitivity of the device.

In addition, the known heat flux density sensor company hukseflux (http://www.hukseflux.com/heat%20flux/hfp01sc.pdf), which is the prototype of the proposed sensor and contains a carrier base with a diameter of 80 mm and a thickness of 5 mm, which is made of heat-insulating material (for example, rubber) and due to this allows you to convert the density of the heat flux into a temperature difference. There is also a battery of metal thermocouples (200 pcs.), With a coefficient of thermoEMF of the order of 40 μV / K, as a thermoconverter of the temperature difference into an electrical signal. Thermocouples are perpendicular to the carrier base, that is, the ends of the thermocouple are connected to the upper and lower sides of the base (application). Under the action of the heat flux in the carrier base, a temperature difference occurs, which can be determined by the formula:

Where p is the heat flux density, W / m ² ;

λ is the coefficient of thermal conductivity, W / (m · K).

ΔT is the temperature difference between the hot and cold sides of the carrier base, K;

ΔХ - thickness of the bearing base, m

The resulting temperature difference is converted into an output electrical signal using a thermocouple battery according to the formula:

where ΔЕ is the value of thermo-EMF, V;

α _T - coefficient of thermo-EMF, V / K;

Δ _T is the temperature difference of thermocouple junctions, K.

n is the number of thermocouples.

The temperature range of the prototype device from -30 ° to + 70 ° C.

However, this device has a supporting base, with metal thermocouples parallel to the incident heat flux and having a low coefficient of thermoEMF. Therefore, this device has a small sensitivity of 50 μV · m ² / W and a narrow temperature range from -30 ° to + 70 ° C.

The task of the invention is to increase the sensitivity of the sensor and expand the temperature range.

This object is achieved by the fact that a concentrator located on the central part of the carrier base, which is made in the form of a silicon profiled membrane on which the indicated thermocouple battery made in the form of polysilicon-aluminum is placed, is introduced into the known heat flux density sensor containing a bearing base and a thermocouple battery mesostructures and coated with a layer of protective dielectric oxide.

The drawing shows a structural diagram of the proposed device.

The proposed device contains a carrier base 1, a battery of polysilicon-aluminum thermocouples 2, a hub 3, a heat-insulating ring 4. On a carrier base 1 are a battery of thermocouples 2 and a heat-insulating ring 4, as well as a hub 3 located on the central part of the carrier.

The device operates as follows: under the action of the heat flux in the carrier base 1, a temperature difference arises between the central part and the side. In turn, the battery of polysilicon-aluminum thermocouples 2 converts the resulting temperature difference into an output electrical signal according to formula 2. For electrical isolation from each other, the polysilicon branches of thermocouples 2 are made in the form of mesostructures and are coated on top with a layer of protective oxide. This gives an increase in the upper limit of the temperature range to 250 ° C.

The concentrator 3 allows you to transfer the heat flux directly to the central part of the carrier base 1. The heat flux density p ₁ transmitted by the concentrator 3 to the central region of the carrier base 1 is

;

Where p ₂ is the density of the incident heat flux;

S ₁ - the contact area of the hub 3 with the Central part of the carrier base.

S ₂ - the area of the base of the concentrator 3, which falls the measured heat flux.

Ring 4 is necessary for fixing the hub 3 relative to the carrier base 1.

Thus, in comparison with the prototype, the proposed heat flux sensor has a higher sensitivity of the order of 160 μV * m2 / W. This is due to the fact that, firstly, a silicon profiled membrane is used as the supporting base, which together with the concentrator allows you to create a temperature difference in the direction perpendicular to the measured heat flux. Secondly, the materials of thermocouples, which are located on a carrier basis, so that their junctions are on the central and lateral parts of the membrane, are polysilicon and aluminum, which provides a thermoelectric coefficient of about 120 μV / K.

Claims (1)

1. A heat flux density sensor containing a carrier base and a thermocouple battery, characterized in that a concentrator is inserted in it, located on the central part of the carrier base, which is made in the form of a silicon profiled membrane on which the indicated thermocouple battery made in the form of polysilicon aluminum mesostructures and coated with a layer of protective dielectric oxide.