EP3598011B1

EP3598011B1 - Method of control for thermal and pneumatic performance of an air curtain

Info

Publication number: EP3598011B1
Application number: EP19186966.8A
Authority: EP
Inventors: Pavel Holub; Pavel Simecek
Original assignee: Stavoklima SRO
Current assignee: Stavoklima SRO
Priority date: 2018-07-19
Filing date: 2019-07-18
Publication date: 2022-08-24
Anticipated expiration: 2039-07-18
Also published as: CZ307950B6; EP3598011A1; CZ2018362A3

Description

Field of the Invention

The invention concerns the field of the method of control of heat loss through door openings of civil structures by the control of thermal and pneumatic performance of an air curtain fitted with an infrared detector.

Background of the Invention

Document DE4420167 (C1 ) discloses the known method of control by temperature measuring using an infrared radiation detector. The detector is configured to measure a temperature profile that includes the area passing through the air curtain basically in horizontal direction and substantially perpendicularly to the air curtain. The temperature measured in this area is compared to the saved reference temperature profile. The air curtain is controlled based on such comparison.
Also the DE 4 420 167 (C1 ) publication deals with temperature measuring; in this case the air curtain is fitted with infrared detectors focused on the floor to detect the temperature of the floor. The air curtain is controlled depending on signals from the infrared detectors. The air curtain control is performed by the adjustment of fan revolutions and directing the discharge nozzle to guide the air flow and ensure the required temperature on the floor.
WO 2015/041616 discloses an automatically controlled air curtain device, comprising a set of electronic sensors and a keypad, both communicating with an electronic circuitry for controlling the electric power source supplying to the motor. The set of electronic sensors comprises an infrared sensor detecting radiating from objects in its working area. Thus, the solution described in WO 2015/041616 is similar to the DE 44 20 167 with an addition of the keypad.
The WO 2014/204297 (A1 ) publication also discloses the air curtain that monitors a floor temperature gradient using an infrared detector. Based on results of such measurements, operating parameters of the air curtain, such as the curtain air temperature, fan revolutions, and curtain air flow direction, are adjusted. In addition, the air curtain can be fitted with a detector to detect persons entering the door. Additional detectors detect external conditions, such as wind gusts, sunshine, and air temperature. As far as wind gusts are concerned, it can be assumed that a pressure change that is compared to air pressure inside the building is concerned. The control of the air curtain according to measured temperature differences can be as follows: a change in the value of fan revolutions, a change in the value of air input/output, a change in the value of the air curtain temperature, and a change in the direction of air flow.
The DE 19 542 714 (A1 ) patent application discloses the air curtain control based on the comparison of air pressure inside the separated spaces. The parameters of the air curtain are then adjusted to create a difference eliminating the air curtain permeability. In one embodiment of the invention, air sucked from the outside and directed towards the air curtain is pre-heated in the case that it is too cold to eliminate its negative impact on the resulting parameters of the air curtain.
A disadvantage of the so far used method of control of the intensity and temperature of air coming out of the air curtain by measuring its temperature is the time required for the ascertainment of conditions in the ambient environment of the door opening equipped with the air curtain that is too long to provide for efficient control of air flow intensity and temperature. During this time, changes in climatic conditions in the space subject to monitoring near the air curtain may occur to which the current methods of control are not able to respond in a timely manner.
Due to the facts mentioned above, the currently used method of control of the temperature of air leaving the air curtain has higher energy demands for operation and a lower efficiency of separating the outer climatic changes from the internal microclimate. The state-of-the-art solutions install the air curtain in the area of the door opening to minimize the effect of external climatic conditions on the internal microclimate at the time when the door opening is opened. Such climatic conditions may include the temperature, humidity, and quality of air, such as the content of odour and dust. The quality of the air curtain functionality is affected by the values of parameters characterizing internal microclimate and external climate.
Such parameters may include air temperature and dew point, wind and its direction, direct solar radiation, and the content of gaseous and solid air pollutants. The parameters mentioned above and their changes in real time affect the quality of the air curtain functionality. To ensure reliable functioning, the air curtain is amply dimensioned in a majority of cases and therefore consumes more heat and power than necessary. In general, the air curtain has higher energy demands than necessary in cases where the internal microclimatic and external climatic changes are only moderate and a lower energy input provided within a tenth of the usual time would be sufficient.
The task of the invention is to find a way of the air curtain control method that would remove the drawbacks of the known solutions and allow faster detection of changes in climatic conditions in the interior and exterior within a tenth of the usual time compared to the so far method that is based on temperature measurements only. The invention should also allow the detection of comprehensive temperature situation in the interior and exterior in real time with only one or a very limited number of detectors unlike in the case of the current measurement of temperature with a plurality of detectors covering defined points and temperature profiles and the necessity of the comparison thereof with preset reference values. The result of the method should be the control of thermal and pneumatic performance of the air curtain that is capable of quick adjustment to the current temperature conditions to realize a saving of power and heat.

Summary of the Invention

The set goal has been achieved by designing the method of control for thermal and pneumatic performance of the air curtain according to the present invention. The controlled air curtain is arranged on the interior side of the door opening in horizontal position above the door or in vertical position next to the door, and is equipped with the control system for operation, thermal and pneumatic performance of the air curtain that is interconnected with at least one interior infrared radiation detector. The essence of the method according to the invention rests in the fact that the control is executed in the following steps:

a) the infrared radiation detector detects infrared radiation reflected at an angle of α ranging from 5° to 80° to the normal line of the interior reflecting surface on the interior side,
b) first of all, the infrared radiation detector measures the spectral specific radiant intensity of infrared radiation M_λs [W/cm² µm] from the interior reflecting surface with the door closed,
c) then the infrared radiation detector measures the spectral specific radiant intensity of infrared radiation M_λs [W/cm² µm] reflected from the interior measured reflecting surface with the door opened, or the spectral specific radiant intensity of infrared radiation M_λs [W/cm² µm] reflected from the exterior reflecting surface is measured, also at an angle ranging from 5 to 80° to its normal line with the door opened,
d) then the values measured in steps b) and c) are compared and their difference Δ M_λs is ascertained within the range of the analog or digital output of the infrared radiation detector that characterizes the change in the spectral specific radiant intensity of infrared radiation Δ M_λs [W/cm² µm] emitted and reflected by the surface of the measured reflecting surface,
e) based on the difference Δ M_λs determined as per step d) the control system analyses the output of the infrared radiation detector for the up-to-date correction of the pneumatic and thermal performance and adjustment of the air flow direction of the air curtain.

In a preferred embodiment of the method according to the invention, the air curtain control system performs, based on the difference Δ M_λs determined as per step d), the self-adaptive correction of the preliminary setting of the control process with the predictive control of the air curtain for the subsequent control process for the opening/closing of the door opening.
In another preferred embodiment according to the invention, the difference Δ M_λs of the spectral specific radiant intensity of infrared radiation that is induced only by the reflection of infrared radiation with the suppression of reflecting surfaces emissivity is measured. This task is performed by measuring the spectral specific radiant intensity of objects the optical reflection of which within the range from 8 to 15 µm is detected on the measured reflecting surface by which the infrared radiation detector is calibrated for at least partial suppression of the detection of infrared radiation emission from the measured reflecting surface, and for the predominant detection of the reflection component of infrared radiation from the measured reflecting surface.
In other preferred embodiments of the method according to the invention the infrared radiation detector detects the specific radiant intensity induced by the reflection of infrared radiation that impacts the interior measured reflecting surface on the floor or on the door or positioned in parallel to the floor, or perpendicularly to the floor, or at an angle to the floor. The infrared radiation detector is integrated in the body of the air curtain or is arranged separately from the body of the air curtain.
The essence of the method according to the invention rests in the fact that it is not the temperature of the surface, e.g. the floor, what is detected, but the reflection at an angle of α of infrared radiation from the floor or other reflecting surface with a low value of emissivity of infrared radiation as far as possible, or such emissivity is suppressed by the calibration of the detector. The advantage of the approach rests in the fact that the infrared radiation detector detects the change in the spectrum of infrared radiation in the reflection immediately when the door opening between the interior and the exterior is opened, even before the temperature, for example on the floor, changes.
The advantage is that the infrared radiation detector and the related control system is immediately able to analyse the difference of temperature conditions between the interior and the exterior upon closing/opening the door opening between the interior and the exterior based on the difference of the spectrum composition or based on the change in the spectral specific radiant intensity of infrared radiation M_λs [W/cm² µm]. The method according to the invention allows changes that occurred to be ascertained without any delay and to control the thermal and pneumatic performance of the air curtain. The time response is faster by one order than in the case of control based on temperature, i.e. according to the state of the art. A change in temperature is basically a change in infrared radiation emission of the reflecting surface directly related to its surface temperature. It is very slow and very small within the short period of time between the door opening and closing and the control of this quantity results in the disadvantages of the state of the art mentioned above.
On the other hand, a change in the spectral specific radiant intensity of infrared radiation M_λs [W/cm² µm] on the surface subject to monitoring expresses a comprehensive change in temperature conditions in the interior upon opening and closing the door opening, and changes very quickly, which means that it allows even faster control requiring a lower thermal and electric output.

Overview of Figures in Drawings

The invention will be explained in detail by drawings where the following is illustrated:

Fig. 1: Detection of infrared radiation reflection on the interior measured reflecting surface on the floor on the interior side with the door closed,
Fig. 2: Detection of infrared radiation reflection on the interior measured reflecting surface on the door on the interior side with the door closed,
Fig. 3: Detection of infrared radiation reflection on the interior measured reflecting surface on the floor on the interior side with the door opened,
Fig. 4: Detection of infrared radiation reflection on the exterior measured reflecting surface on the floor on the exterior side with the door opened,
Fig. 5: Detection of infrared radiation reflection on the horizontal auxiliary reflecting surface on the interior side with the door opened,
Fig. 6: Detection of infrared radiation reflection on the adjustable auxiliary reflecting surface on the interior side with the door opened,
Fig. 7: A chart representing the relation between the spectral specific radiant intensity of infrared radiation Δ M_λs [W/cm² µm] and the infrared radiation wavelength λ [µm]. The cross-hatched area represents the range of the used wavelengths.

Examples of the Invention Embodiments

The room shown in Fig. 1 through Fig. 6 is separated from the external environment of the exterior by the door opening 3 fitted with the door 4. The door 4 can be moved out using a drive that is not provided in the figure, either above the door opening 3 or next to the door opening 3. The side extending from the door opening 3 towards the inside of the room is called the interior side 2. The side extending from the door opening 3 towards the outside of the room is called the exterior side 11. Above the door opening 3, and/or next to the door opening 3, the air curtain 1 is installed. It is equipped with the control system 5 controlling the operation and the thermal and pneumatic performance of the air curtain 1. Specifically, it initiates and controls the pneumatic performance of the ventilator(s) integrated in the air curtain 1, controls the heat output of the hot-water or electric heat exchanger that warms up the air flow coming out of the air curtain 1, and it also controls the direction of air flow more or less towards the door opening 3. On the interior side 2, the interior detector 6 of infrared radiation 7 is installed, which is interconnected with the control system 5 and which can be integrated in the body of the air curtain 1, as provided in Fig. 1 through Fig. 6, or can be positioned separately from the air curtain 1 as provided in the embodiment out of the scope of the drawings.
The detector 6 refers to a general commercially available detector of infrared radiation 7 with the range of wavelengths from 8 to 14 µm, the output of which is an analog output signal, for example 0-10 V, 4-20 mA, 0-100 Ω, etc., or a digital output, e.g. USB, RS 485, RS 232, DS18B20, TSic, etc. The sensitivity of the detector 6 of infrared radiation 7 within the range from 8 µm to 15 µm is set in a manner allowing the reflection of infrared radiation 7 from the measured reflecting surface 8 , 8 ', 10 , 12,13 to be detected to the greatest extent, and to suppress detection of infrared radiation 7 emitted by the measured reflecting surface 8, 8' , 10, 12, 13 to the greatest extent. The used commercially available detector 6 of infrared radiation 7 is generally fitted with a processor and software allowing sensitivity adjustment.
After this calibration, the detector 6 permanently analyses changes in the spectral specific radiant intensity of infrared radiation Δ M_λs [W/cm² µm] reflected by the surface of the measured reflecting surface 8, 8' , 10, 12, and 13 with suppressed emissivity. It is possible to control the air curtain 1 even without the calibration of the detector 6, but in such a case the control will not be accurate and fast enough for the following reasons:
The energy of the spectrum of infrared radiation 7 impacting the sensitive sensing surface of the detector 6 is the sum of the energy of emission ε of the detected body, in this case the reflecting surface 8, 8', 10, 12, 13, its transmission τ, and reflection ϕ. In general, the following applies: $ε + φ + τ = 1$
The transmission component τ is not applicable in this case, which means that it equals 0. Then, the following applies ε + ϕ = 1
In all methods of the air curtain 1 control, known based on the state of the art, the detector 6 is designed only for the measurement of the emissivity of the body surface subject to monitoring, i.e. its surface temperature, where the effect of reflection is suppressed by calibration and compensated to such an extent not to affect the measured temperature of the body surface to the acceptable extent of measuring error.
On the other hand, the present invention includes no measurement of a change in surface temperature, i.e. emissivity, but the measurement of a change in the spectral specific radiant intensity of infrared radiation Δ M_λs [W/cm² µm] emitted and reflected, or where applicable, reflected only, by the surface of the measured reflecting surface 8, 8', 10, 12, and 13. This means that the adjustment of calibration of the detector of infrared radiation 7 is executed in the reverse direction to suppress the detection of the infrared radiation 7 emission to the maximum extent. The emissivity of the surface, the temperature of which is measured according to the already known method, is detected as far as possible perpendicularly to the surface to eliminate the effect of reflection. Then another effect supporting the detection of reflection according to the invention is the adjustment of the detector 6 of infrared radiation 7 in a manner to have the reflecting surface 8, 8', 10, 12, and 13 positioned to the detector 6 of infrared radiation 7 at an angle of α, that is not 90°, but ranges from 5 to 80°.
The detector 6 of infrared radiation 7 is either integrated in the air curtain 1, or it is positioned outside the air curtain 1. The air curtain 1 is installed in horizontal direction above the door opening 3 or in vertical direction next to the door opening 3, namely at different heights from the floor 9 and at a different distance from the door opening 3, depending on the installation conditions on the site. The door opening 3 always has a different width and height, which is reflected by the position of the air curtain 1 to the reflecting surfaces 8, 8', 10, 12, 13. The detector 6 of infrared radiation 7 is adjusted in a manner to detect at an angle of α the reflection of infrared radiation 7 on the reflecting surface 8, 8', 10, 12, 13 selected in a preferred way. The detector 6 of infrared radiation 7 measures the spectral specific radiant intensity of infrared radiation M_λs [W/cm² µm] reflected at an angle of α ranging from 5° to 80° to the normal line of the reflecting surface 8, 8', 10, 12, 13 with the door 4 closed, and possibly of the exterior reflecting surface 10 with the door 4 opened, depending on the method of installation of the air curtain 1 and detector 6. Within the range of its analog or digital output, the detector 6 of infrared radiation 7 transfers the value of M_λs [W/cm² µm], the spectral specific radiant intensity, to the control system 5. The reflection of infrared radiation 7 is detected at an angle of α ranging from 5° to 10° in the embodiment of the measuring and control system where the detector 6 is integrated in the horizontally installed air curtain 1 above the door opening 3 and the reflecting surface 8 refers to the interior side of the floor 9. The reflection of infrared radiation 7 is detected at an angle of α ranging from 70° to 80° in the embodiment where the detector 6 is integrated in the horizontally installed air curtain 1 above the door opening 3 and the reflecting surface 8 refers to the interior surface of the door 4 with the door 4 closed. The reflection of infrared radiation 7 is detected at an angle of α ranging from 10° to 20° in the embodiment of the measuring and control system where the detector 6 is integrated in the horizontally installed air curtain 1 above the door opening 3 and the reflecting surface 10 refers to the floor 9 on the exterior side 11 of the door 4 with the door 4 opened. The reflection of infrared radiation 7 is detected at an angle of α ranging from 20° to 40° in the embodiment of the measuring and control system where the detector 6 is integrated in the horizontally installed air curtain 1 above the door opening 3 or in the vertically installed air curtain 1 next to the door opening 3 and the reflecting surface refers to the adjustable auxiliary reflecting surface 12, 13 on the interior side 2. The reflection of infrared radiation 7 is detected at an angle of α ranging from 20° to 60° in the embodiment of the measuring and control system where the detector 6 is integrated in the vertically installed air curtain 1 next to the door opening 3 and the reflecting surface 8 refers to the interior part of the floor 9.
With the door opening 3 closed by the door 4, the detector 6 of infrared radiation 7 detects the reflection of infrared radiation 7 on some of the reflecting surfaces 8, 8' , 12, and 13 within the spectrum corresponding to temperature conditions of the interior microclimate on the interior side 2. The reflecting surface 8, 8' , 12, and 13 can refer to the floor 9 of the interior, the surface of the door 4, or other surfaces and objects in the interior; the situation with the exterior reflection surface 10 is similar. These surfaces are situated near the door opening 3 at different angles to the position of the detector 6 of infrared radiation 7. These surfaces can have various shapes, such as flat, cylindrical, concave, convex, etc. The horizontal auxiliary reflecting surface 13 and the adjustable auxiliary reflecting surface 12 will be used with the measuring and control system where for example in a preferred position for the detection of the reflection of infrared radiation 7, surfaces with a high value of emissivity occur and the reflection of infrared radiation 7 is difficult to detect. In addition, it will be employed in the case of installation of the vertical air curtain 1 next to the door opening 3 where direct detection of infrared radiation 7 on the exterior side 11 is not possible. Where employed, the horizontal auxiliary reflecting surface 13 or adjustable auxiliary reflecting surface 12 will be installed onto the floor 9, wall or ceiling on the interior side 2 of the door opening 3. The horizontal auxiliary reflecting surface 13 or adjustable auxiliary reflecting surface 12 can also refer to an object used for a different function, such as a cupboard, flower pot, information board, etc. If the door 4 separating the interior side 2 and the exterior side 11 is closed, the detector 6 of infrared radiation 7 detects the reflection of infrared radiation 7 of some of the reflecting surfaces 8, 8', 12, 13. Its state is expressed by the value of the spectral specific radiant intensity of infrared radiation M_λs [W/cm² µm] and the output signal for the control system 5 of the air curtain 1.
Upon opening the door 4 the spectrum of infrared radiation 7 changes depending on the difference of temperature conditions between the interior side 2 and the exterior side 11, which means that if the interior is hot and the exterior cold, the portion of radiation with a lower value of energy and a higher value of wavelength increases and the portion of radiation with a higher value of energy and a lower value of wavelength decreases, which will be manifested by a change, a decrease of the spectral specific radiant intensity M_λs [W/cm² µm] according to the chart in Fig. 7. Such a change will manifest itself within a period of time that only depends on the speed of the door 4 opening. Here, the advantage of measuring reflection of infrared radiation 7 instead of the so far measuring of infrared radiation emission by objects (temperature of object surfaces) where a detectable change occurs after a considerably longer period of time is fully manifested.
The detector 6 analyses the state after the door 4 opening, expresses it by the value of the spectral specific radiant intensity of infrared radiation M_λs [W/cm² µm] and the corresponding output signal for the control system 5 of the air curtain 1. The control system 5 of the air curtain 1 detects the change immediately, which means for example upon opening the door 4. The control system 5 of the air curtain 1, based on data provided by the detector 6, analyses the difference Δ M_λs as a change of the spectral specific radiant intensity of infrared radiation Δ M_λs [W/cm² µm] reflected by the surface of the measured interior reflecting surface 8, 8', 12, and 13, or where applicable, of the exterior reflecting surface 10. The control system 5 of the air curtain 1 compares the state prior to the door 4 opening and after the door 4 closing, and compares it to the required result that is preset in the control system 5 of the air curtain 1 based on previous self-adaptive processes or as a fixed value. Based on a possible deviation, the control system corrects the preset parameters of the air curtain 1 operation for the following process of opening/closing the door 4. The processor and software for the conversion of the value M_λs [W/cm² µm] into a unified signal or data output for the control system 5 are integrated in the detector 6; other processors or software can be integrated in the control system 5 as well.
To control the thermal and pneumatic performance of the air curtain 1, a plurality of the detectors 6 of infrared radiation 7 detecting different combinations of the reflecting surfaces 8, 8', 10, 12, and 13 can be used. Each of them can detect the reflection of infrared radiation 7 from the surfaces of the reflecting surfaces 8, 8', 10, 12, and 13 with different physical properties. A preferred control system 5 of the air curtain 1 can work with output signals of a plurality of detectors 6 of infrared radiation 7 , thus eliminating interference signals, such as a person or foreign objects in the field of view of the detector 6 of infrared radiation 7.

Industrial Applicability

The method according to the invention can be employed in the field of air-conditioning, installation of new air curtains and during reconstruction and replacement of the previous air curtains with a considerably higher energy demands for operation and a lower efficiency of shielding the internal microclimate of the interior from the external climate of the exterior.

Overview of the Positions used in the Drawings

1: air curtain
2: interior side
3: door opening
4: door
5: air curtain control system
6: interior infrared detector
7: infrared radiation
8: interior measured reflecting surface on the floor
8': interior measured reflecting surface on the door
9: floor
10: exterior measured reflecting surface
11: exterior side
12: adjustable auxiliary reflecting surface
13: horizontal auxiliary reflecting surface
α: infrared radiation reflecting angle
Mλs: [W/cm² µm] spectral specific radiant intensity of infrared radiation
Δ Mλs: difference of spectral specific radiant intensity

Claims

A method of control for thermal and pneumatic performance of an air curtain (1) arranged on an interior side (2) of a door opening (3) in horizontal position above a door (4) or in the vertical position next to the door (4) and equipped with a control system (5) for the operation of the thermal and pneumatic performance of the air curtain (1), which is interconnected with at least one interior detector (6) of infrared radiation, characterized in that the control is performed in the following steps:
a) the detector (6) of infrared radiation (7) detects infrared radiation (7) reflected at an angle of α ranging from 5° to 80° to the normal line of the reflecting surface (8,8', 12,13) on the interior side (2),

b) first of all, the detector (6) of infrared radiation (7) measures the spectral specific radiant intensity of infrared radiation M_λs [W/cm² µm] from the reflecting surface (8,8',12,13) on the interior side (2) with the door (4) closed,

c) then the detector (6) of infrared radiation (7) measures the spectral specific radiant intensity of infrared radiation M_λs [W/cm² µm] reflected from the reflecting surface (8,8',12,13) on the interior side (2) with the door (4) opened, or the detector (6) measures the spectral specific radiant intensity of infrared radiation M_λs [W/cm² µm] reflected at an angle of α ranging from 5° to 80° to the normal line of the exterior measured reflecting surface (10) positioned on the floor (9) in the area of the door opening (3) on its exterior side (11) with the door (4) opened,

d) then the values measured in step c) and b) are compared and their difference Δ M_λs is ascertained within the range of the analog or digital output of the detector (6) of infrared radiation (7) that characterizes the change in the spectral specific radiant intensity of infrared radiation Δ M_λs [W/cm² µm] emitted and reflected by the surface of the measured reflecting surface (8,8',10,12,13),

e) the difference Δ M_λs determined according to step d) as a difference of temperature conditions between the interior and the exterior is compared in the control system (5) with the required value that is preset in the control system (5), and an up-to-date correction of the thermal and pneumatic performance and setting the air flow direction of the air curtain (1) is performed.
The method according to claim 1, characterized in that based on the difference Δ M_λs determined as per step d) in patent claim 1, the control system (5) of the air curtain (1) executes a self-adaptive correction of the preliminary setting of the control process with the predictive control of the air curtain (1) for the subsequent control process for the opening/closing of the door opening (3).
The method according to claim 1 or 2, characterized in that the difference Δ M_λs of the spectral specific radiant intensity induced in particular by the reflection of infrared radiation (7) is measured and during the measurement of the spectral specific radiant intensity M_λs of objects, the optical reflection of which ranges from 8 to 15 µm, is detected on the reflecting surface (8,8',10,12,13), the detector (6) of infrared radiation (7) is calibrated for at least a partial suppression of the detection of emission of infrared radiation (7) from the measured reflecting surface (8,8',10,12,13) and for the predominant detection of the reflection component of infrared radiation (7) from the measured reflecting surface (8,8',10,12,13).
The method according to any of claims 1 through 3, characterized in that the detector (6) of infrared radiation (7) detects the specific radiant intensity induced by the reflection of infrared radiation (7) that impacts on the interior side (2) the measured interior reflecting surface (8) situated on the floor (9), or the measured interior reflecting surface (8') situated on the door (4), or the adjustable auxiliary reflecting surface (12) positioned vertically or diagonally, or the horizontal auxiliary reflecting surface (13).