WO2017138846A1

WO2017138846A1 - Thermoelectric ice-formation sensor

Info

Publication number: WO2017138846A1
Application number: PCT/RU2017/000063
Authority: WO
Inventors: Геннадий Гюсамович ГРОМОВ
Original assignee: Геннадий Гюсамович ГРОМОВ
Priority date: 2016-02-10
Filing date: 2017-02-09
Publication date: 2017-08-17

Abstract

The proposed utility model relates to warning and monitoring means and may be used for remotely detecting ice formation and for determining environmental conditions similar to those in which ice forms or is predisposed to forming on various surfaces. A thermoelectric sensor for detecting ice formation or predisposition to ice formation on a surface contains a thermoelectric module in the form of a Peltier element. The sensor for detecting ice formation is provided with a thermoelectric heat-flow sensor, the bottom portion of which is connected to the Peltier element, and the opposing top portion of which forms an external surface which is sensitive to ice formation. The top portion of the thermoelectric heat-flow sensor contains a temperature sensor. The present invention enhances sensitivity to ice formation or to a predisposition to ice formation while simultaneously increasing metrological precision in determining ice formation or a predisposition to ice formation.

Description

THERMOELECTRIC ICE SENSOR

Technical field

The proposed utility model relates to means of signaling and control and can be used for remote detection of icing and determination of environmental conditions similar to conditions for the formation or predisposition to icing of various surfaces, for example, surfaces of aircraft, in particular the fuselage, wings, propellers or aircraft rotor blades.

State of the art

The appearance of ice on the roadways, as well as on the runways of airports or the appearance of conditions close to the conditions for the formation of ice cover, significantly affects the safety of vehicles and, accordingly, the success of take-off and landing of aircraft.

Ice formation on the surface of aircraft, in particular, ice growing on the fuselage, wings, propellers, rotor blades and control surfaces of aircraft can create difficulties for piloting, adversely affecting the controllability of the aircraft.

The probability of occurrence of ice cover depends on local environmental conditions, such as atmospheric temperature, atmospheric pressure, air humidity, etc.

In this regard, there is a need to use new modern devices that signal the formation of ice cover or the conditions for its formation in order to timely prevent the occurrence of ice cover or its prompt elimination.

Currently, a large number of icing sensors are used, the operation of which is based on various direct or indirect methods for determining the presence of icing or a predisposition to icing.

Mostly icing indicators are used, which, mainly on the basis of various physical principles, determine the presence of ice on various surfaces in such a way as to generate an indication the occurrence of ice or a warning about the existence of conditions for the formation of ice.

So, the prior art technology for generating signals about the appearance of a water film of surfaces on the street (see W09913295, class G01B21 / 08, publ. March 18, 1999 [1]).

The appearance of a water film on any surface is associated with the likelihood of converting it into ice cover, and the idea of the known technology [1] is that the device determines the thickness of the water film, which determine the possible freezing point. Depending on the parameters of a particular section of the aqueous film, it is heated or cooled, and the film thickness is determined by analyzing the temperature limits during heating or cooling. In this case, the Peltier element is used to heat or cool an aqueous film, the temperature of which is measured using a thermocouple and calculated using a microprocessor.

The known technology [1] is more relevant to forecast methods and is indirectly able to determine icing of surfaces on the street, since the thickness of the liquid film on the surface is analyzed without taking into account other important factors that can lead to ice formation, for example, temperature drops, changes in atmospheric pressure or humidity, which in turn negatively affects accuracy and, as a consequence, the reliability of fixing the formation of ice cover. In addition, this technology [1] does not provide for the possibility of predicting the appearance of atmospheric conditions favorable for ice formation.

The prior art device for detecting the formation of ice (see US6456200, CL G08B 19/02, publ. 09/24/2002 [2]).

The design of the known device [2] uses a Peltier thermoelectric element as a device for measuring the temperature difference. Ice formation is detected by measuring changes in the heat flux due to the release of latent heat during the ice formation process, which causes the generation of stress at the ends of the Peltier element.

The disadvantage of this device [2] is that it is able to determine the conditions for the formation of icing only after the ice crust formed, and is not able to determine how close local conditions are to the conditions for ice formation or whether these conditions change and how quickly this happens.

This device for detecting the formation of ice [2] becomes especially ineffective when the air temperature is close to the freezing point or slightly lower.

The prior art method and system for detecting the probability of formation of natural ice on the surface of a vehicle (see

US4570881, CL B64D15 / 20, publ. 02/18/1986 [3]).

The known method involves the placement of the diaphragm on the surface of the vehicle, alternate cooling and heating using the element

Peltier of the specified diaphragm to temperatures below and above ambient temperature in accordance with a certain cycle that creates and then melts ice, if the ambient temperature is near or below the freezing point. At the same time, any change in the resonant frequency of the vibration of the diaphragm in the mentioned cycle is recorded alternately and repeatedly cooling and heating the diaphragm, providing an alarm if the specified change in the resonant frequency exceeds a predetermined value.

The known method [3] has an expanded range of functional applications, since in addition to detecting the formed ice cover, a probable predisposition to ice is fixed, and an appropriate alarm signal is given.

The disadvantage of this method is the possible occurrence of vibration transmitted directly from the known system to any surface of the vehicle, which may interfere with the operation of other automated vehicle systems.

In addition, the disadvantage of this method is the inconsistency of the sensitivity of the known system, since the use of a piezoelectric element in its composition will require its calibration.

The closest analogue of the proposed utility model is a thermoelectric icing sensor (see RU2534493, class B64D 15/20, publ.

11/27/2014 [four]). Known thermoelectric icing sensor contains a thermoelectric module made in the form of a Peltier element that performs the function of a heat pump and a temperature sensor mounted on an external sensitive surface.

According to a given algorithm, the Peltier element, depending on the ambient temperature and its proximity to the freezing temperature, heats or cools the sensitive surface. A temperature sensor monitors temperature changes. If there is ice on the surface, the conditions for ice formation are present, the temperature of the sensitive surface is stabilized during the water-ice phase transition and the latent heat of ice formation is absorbed or absorbed. The well-known thermoelectric sensor captures the indicated temperature of the phase transition, thereby determining the presence of ice formation, and the intensity of ice formation is estimated by the power supply of the heat pump (Peltier element) during this period, since this correlates directly with the released or absorbed heat of the phase transition.

Among the disadvantages of the known thermoelectric icing sensor, the following can be noted:

- insufficient sensitivity at low intensity of ice formation, the accuracy is determined by the accuracy of the temperature sensor and the algorithm for tracking temperature changes; with a small temperature step or a high speed of its passage, the required level of accuracy for fixing ice formation will not be provided;

- in the cooling cycle, ice formation is determined satisfactorily by stabilization of the phase transition temperature (water crystallization) for a certain time, and in the heating cycle, this stabilization (melting of the ice layer) is less noticeable, therefore, in the heating cycle, the determination of ice formation is very difficult;

- assessment of the intensity of ice formation by the energy spent by the Peltier element is an indirect method that does not take into account the significant dependence of the consumed power of the Peltier element on the ambient temperature, heat transfer, etc. . Utility Model Disclosure

The objective of the proposed utility model is to create a multifunctional efficient and reliable means for detecting icing or a predisposition to icing of various surfaces directly in a direct and accurate way.

The technical result of the proposed thermoelectric sensor is to increase the sensitivity of ice formation or predisposition to it while increasing the metrological accuracy of determining ice formation or predisposition to its occurrence.

The specified technical result, which is objectively manifested as a result of using the proposed utility model, is achieved due to the fact that the thermoelectric sensor for detecting icing or predisposition to icing of the surface contains a thermoelectric module made in the form of a Peltier element, while the thermoelectric sensor is equipped with a connected lower part to the Peltier element thermoelectric heat flow sensor, opposite upper part, which forms an external sensitive formation of ice surface and is provided with a temperature sensor.

The proposed multifunctional thermoelectric sensor for determining icing or a predisposition to icing contains a thermoelectric heat flow sensor, the outer surface of the upper part, which is sensitive to the formation of ice, and is also sensitive to the formation of weather conditions that form the ice cover. The lower part of the heat flux sensor is connected (interacts) with a thermoelectric module made in the form of a Peltier element, which, depending on the direction of the applied current, can both heat and cool the heat flux sensor and, accordingly, its external sensitive surface of the upper part. A temperature sensor is connected to the top of the heat flux sensor.

The thermoelectric module, made in the form of a Peltier element, provides cyclic heating - cooling of the sensitive outer surface of the upper part of the heat flux sensor in the temperature range of ice formation. b

In the case of ice or a predisposition to ice formation on the sensitive outer surface of the upper part, a thermoelectric heat flow sensor detects the generation or absorption of latent heat of ice formation by the appearance of a signal corresponding to the heat flux through it, while the temperature sensor detects the ice formation temperature.

Additionally, the proposed thermoelectric icing detection sensor has the ability to calculate the intensity of ice formation and the thickness of the ice layer by integrating the heat of the heat flux passed through the sensor over the time period of ice formation at a known specific heat of ice formation.

The indicated features of the proposed utility model provide the creation of a multifunctional effective and reliable means for detecting icing or a predisposition to icing of various surfaces and, accordingly, achieving a technical result consisting in increasing the sensitivity of ice formation or predisposition to it while increasing the metrological accuracy of determining ice formation or predisposition to ice formation.

Brief Description of the Drawings

In FIG. 1 shows the design of the proposed thermoelectric sensor;

In FIG. 2 shows the cyclic change in temperature of the heat flow sensor using the Peltier element (a - cooling cycle, c - heating cycle);

In FIG. 3 shows the temperature change on the surface of the Peltier element and on the sensitive surface of the heat flux sensor at different thicknesses of the water layer, in increasing order (cooling cycle);

In FIG. 4 shows the readings of the heat flux sensor, at different thicknesses of the ice layer, in increasing order (cooling cycle);

In FIG. 5 shows the temperature change on the surface of the Peltier element and on the sensitive surface of the heat flux sensor at different thicknesses of the water layer, in increasing order (heating cycle);

In FIG. 6 shows the readings of the heat flux sensor, at different thicknesses of the ice layer, in increasing order (heating cycle). Utility Model Implementation

The utility model is illustrated by a specific implementation example, which, however, is not the only possible, but clearly demonstrates the achievement of a given set of essential features of a given technical result.

In FIG. 1 displays the following elements and parameters of the proposed thermoelectric sensor:

1 - thermoelectric heat flow sensor;

2 - thermoelectric module made in the form of a Peltier element;

3 - temperature sensor;

UD is the signal of the heat flux sensor;

Q is the measured heat flux;

I is the supply current of the thermoelectric module, made in the form of a Peltier element;

UT - temperature sensor signal;

T is the measured temperature.

In FIG. Figure 2 shows the following parameters during cyclic changes in the temperature of the heat flux sensor using a Peltier element (a - cooling cycle, c - heating cycle):

A is water;

In - ice;

T _a - ambient temperature;

Ti — temperature on the surface of a layer of water (a) or ice (c);

T ₂ is the temperature on the surface of the heat flux sensor, which is measured by the temperature sensor 3 (thermal sensor) (Fig. 1);

Tz is the temperature on the surface of the Peltier element 2;

Q is the heat absorbed or generated by the thermoelectric heat flow sensor 1, depending on the operation of the Peltier element 2, as a cooler (a - cooling cycle) or as a heater (c - heating cycle). In FIG. 3 shows the temperature change on the surface of the Peltier element 2 and Ts on the sensitive surface of the thermal flow sensor 1 at various water layer thickness, ascending - T _2-1, T ₂ 2, T _2. ₃ (cooling cycle).

In FIG. 4 shows the readings of the heat flux sensor 1 in the cooling cycle. Q ₀ - heat flow in the absence of an ice layer on the surface, with different thicknesses of the ice layer, ascending - Q _ls Q ₂ , Q ₃ .

In FIG. Figure 5 shows the temperature change on the surface of the Peltier element 2 Tz and on the sensitive surface of the heat flux sensor 1 at different thicknesses of the water layer, in increasing T _2-1> T _2-2 , T ₂ -z (heating cycle).

In FIG. 6 shows the readings of the heat flux sensor 1 in the heating cycle. Q ₀

- heat flow in the absence of an ice layer on the surface, at different thicknesses of the ice layer, in ascending order - Qi, Q ₂ , Q ₃ .

The thermoelectric sensor for detecting icing or a predisposition to icing contains a thermoelectric module made in the form of a Peltier element 2.

The thermoelectric sensor for detecting icing or a predisposition to icing is equipped with a thermoelectric heat flow sensor 1 connected to the lower part 16 to the Peltier element 2, the opposite upper part 1a, which forms an external surface sensitive to the formation and predisposition to ice formation.

The upper part 1a of the thermoelectric heat flow sensor 1 is provided with a temperature sensor 3.

The proposed thermoelectric sensor detects icing or predisposition to icing of the surface, as follows.

A. Cooling cycle (Fig. 2a)

In FIG. Figures 3 and 4 show typical readings of a temperature sensor 3 and a thermoelectric heat flux sensor 1, respectively, during a cooling cycle by a Peltier element 2. Moreover, three time dependences are given for cases of different ice formation intensities on the surface of a thermoelectric heat flux sensor 1, and specifically, on an external ice-sensitive one the surface of the upper part 1a. In the case of ambient temperatures above a typical range of ice formation temperatures, the Peltier element 2 starts to work as a cooler and cools the thermoelectric heat flow sensor 1. Accordingly, the external sensitive surface of the upper part 1a, on which the water layer may be, is cooled.

Since water is prone to overcooling, at the beginning the temperature of the external sensitive surface of the upper part 1a of the thermoelectric heat flow sensor 1 drops below the ice formation temperature, and then quickly returns to the ice formation temperature. Formed temperature "plateau", the duration of which depends on the amount of water which is crystallized in the ice (Fig. 3, _Tr-2- v T 2, T ₂ _-s> respectively).

Thus through the thermoelectric sensor of the heat flux 1 flows the heat of crystallization of water. Since this heat flux is significantly higher than the usual heat flux of thermal conductivity, the thermoelectric heat flux sensor 1 detects the onset of ice formation much more sensitively than the temperature sensor 3.

This allows, according to the indication of the heat flux sensor 1, to fix with high accuracy the time instant of the onset of ice formation. And according to the temperature sensor 3, determine the temperature of ice formation at the time point of the maximum reading of the heat flux sensor 1.

The total value of the passed heat of crystallization Q depends on the amount of water on the outer sensitive surface of the upper part 1a of the thermoelectric heat flow sensor 1. The more water, the greater this total heat (Fig. 4, Qj, Q ₂ , Q ₃ , respectively).

The thermoelectric heat flux sensor 1, as a rule, has a calibration of the measured signal to the power density of the passing heat flux (units W / m) or the total power of the heat flux (units W). This means that the heat flux power integral over a fixed period of ice formation time allows us to establish the total heat Q of this process in units of J / m and J. And from the known specific heat of ice formation With _p = 335 J / kg and

-but

ice density p = 917 kg / m it is possible to accurately determine the thickness h of the ice layer or the total amount (mass) of ice g on the sensitive surface of the upper parts la of the thermoelectric heat flow sensor according to formulas 1 or 2, respectively. h = p (1)

9 = T C)

B. The heating cycle (Fig. 2B).

In FIG. Figures 5 and 6 show typical readings of the temperature sensor 3 of the thermoelectric heat flow sensor 1, respectively, during the heating cycle by the Peltier element 2. Moreover, the time dependences for cases of different ice formation intensities on the sensitive surface of the upper part 1a of the thermoelectric heat flow sensor 1 are shown.

In the case where the ambient temperature is already lower than the assumed ice formation temperature, the Peltier element 2 starts a heating cycle of the thermoelectric heat flow sensor and, accordingly, its sensitive external surface of the upper part 1a.

If there is an ice layer and ice formation temperature is reached, the ice begins to melt. In this case, the temperature change in this layer stops (Fig. 5) and the heat of melting of the ice is absorbed (Fig. 6). The indicated heat flows through the thermoelectric heat flow sensor 1. Since this heat flux is much higher than the usual heat flux of thermal conductivity, the thermoelectric heat flux sensor 1 detects the beginning of ice melting much more sensitively than the temperature sensor 3. This allows, according to the readings of the thermoelectric heat flux sensor 1, to accurately detect the beginning of ice melting. And according to the temperature sensor 3, determine the temperature of ice formation at a time, the maximum reading of the thermoelectric heat flow sensor 1.

The total value of the passed heat of melting ice shows the amount of ice on the outer sensitive surface of the upper part 1a of the thermoelectric heat flow sensor. The more ice, the greater this total heat (Fig. 6, Qi, Q2> b, respectively).

The thermoelectric heat flux sensor 1, as a rule, has a calibration of the measured signal to the power density of the passing heat flux (units W / m) or the total power of the heat flux (units W). This means that the heat flux power integral over a fixed period of ice formation time allows us to establish the total heat Q of this process in units of J / m and J. And from the known specific heat of ice formation C _p = 335 J / kg and ice density p = 917 kg / m, it is possible to accurately determine the thickness h of the ice layer or the total amount (mass) of ice g on the sensitive surface of the upper part 1a of the thermoelectric heat flow sensor according to formulas 1 or 2, respectively.

C. Continuous monitoring

Continuous icing monitoring includes successive heating and cooling cycles with a metrologically accurate determination of icing or a predisposition to icing on the surface in both phases (water crystallization and ice melting).

Moreover, averaging the temperature of ice formation, as well as the amount of water or ice (formulas 1 and 2) over the cooling and heating phases, respectively, will further improve the accuracy of the proposed thermoelectric sensor for detecting icing or a predisposition to icing on the surface.

Thus, the desired technical result is achieved due to the formulated set of essential features, clearly presented below:

- thermoelectric icing detection sensor contains a Peltier element 2;

- the thermoelectric icing detection sensor is equipped with a connected lower part 16 to the Peltier element 2 with a thermoelectric heat flow sensor 1, the opposite upper part 1a, which forms an external surface sensitive to ice formation and is equipped with a temperature sensor 3. The proposed thermoelectric sensor for detecting icing or predisposition to icing of the surface can be widely used in the field of remote detection of icing or predisposition to icing of various surfaces.

Claims

Utility Model Formula

A thermoelectric sensor for detecting icing or a predisposition to icing on the surface, comprising a thermoelectric module made in the form of a Peltier element, characterized in that it is equipped with a thermoelectric heat flow sensor connected to the lower part with a Peltier element, the opposite upper part, which forms an external surface sensitive to ice formation and equipped with a temperature sensor.