CN101484763A - Pulse electrothermal deicing of complex shapes - Google Patents

Abstract

A pulse electrothermal deicing apparatus comprises at least one complex shape characterized by a thickness profile configured to generate uniform power per unit area to melt an interfacial layer of ice. A method of optimizing thicknesses of complex shapes for a pulse electrothermal deicing system includes assigning initial estimates of the pulse electrothermal deicing system parameters. A temperature distribution, a temperature range and a refreezing time produced by a deicing pulse are modeled. Shape thicknesses are adjusted according to the temperature range, deicing pulse parameters are adjusted according to the deicing pulse, and the modeling and adjusting is repeated until the temperature range and the refreezing time are within predetermined limits.

Description

The pulse electrothermal deicing of complicated shape

Related application

That the application requires to submit on May 22nd, 2006, the priority of No. the 60/802nd, 407, all and common unsettled U.S. Provisional Patent Application jointly.That the application still submits on January 24th, 2006, the part continuation application of all and common unsettled PCT/US2006/002283 jointly, PCT/US2006/002283 requires in the U.S. Provisional Patent Application the 60/646th of submission on January 24th, 2005, No. 394, the U.S. Provisional Patent Application the 60/646th submitted on January 25th, 2005, the priority that No. the 60/739th, 506, No. 932 and the U.S. Provisional Patent Application submitted on November 23rd, 2005.This application is still submitted on December 22nd, 2006, common all and common unsettled U.S. Patent application the 11/571st, No. 231 part continuation application, U.S. Patent application the 11/571st, require for No. 231 in the preference of the PCT/US2005/022035 of submission on June 22nd, 2005, PCT/US2005/022035 requires in the U.S. Provisional Patent Application the 60/581st of submission on June 22nd, 2004, No. 912, the U.S. Provisional Patent Application of submitting on January 24th, 2005 the 60/646th, the priority number of No. 394 and the U.S. Provisional Patent Application the 60/646th, 932 submitted on January 25th, 2005.This application is still submitted on January 24th, 2006, common all and common unsettled U.S. Patent application the 11/338th, No. 239 part continuation application, U.S. Patent application the 11/338th, require for No. 239 in the U.S. Patent application the 10/939th of submission on September 10th, 2004, No. 289, be United States Patent (USP) the 7th now, 034, No. 257 priority, U.S. Patent application the 10/939th, No. 289 is to divide an application, it requires in the U.S. Patent application the 10/364th of submission on February 11st, 2003, No. 438, be United States Patent (USP) the 6th now, 870, No. 139 priority, U.S. Patent application the 10/364th, require for No. 438 in the U.S. Provisional Patent Application the 60/356th of submission on February 11st, 2002, No. 476, the priority that No. the 60/404th, 872, No. the 60/398th, 004, U.S. Provisional Patent Application of submitting on July 23rd, 2002 and the U.S. Provisional Patent Application submitted on August 21st, 2002.Incorporate all aforementioned patent applications into this paper by reference.

Background technology

The deicing that produces heat (Joule heat) thawing or separate ice by electricity consumption has a lot of application.During wherein these are used some benefited from and made the energy minimum that is applied to ice and/or ices the object that adheres to.For example, than melt or at least the generation of the necessary heat more heat of separate ice need consuming excessively of energy.In some applications, for example, in the ice making or deicing of chilling unit, the consumption of additional energy is especially disadvantageous when separate ice; Not only melt the deglaciating energy consumption, and the part that cooling system has separated ice again in the cooling system also may consume more energy.

Summary of the invention

In one embodiment, pulse electrothermal ice detachment apparatus comprises at least a complicated shape that is showed its feature by thickness distribution, and it is configured to produce uniform powerperunitarea to melt the boundary layer of ice.

In one embodiment, a kind of method of thickness of the complicated shape of optimizing the pulse electrothermal deicing system comprises: be the every kind of shape specified size and the geometry of pulse electrothermal deicing system, and the connectivity of designated shape; For every kind of shape is specified original depth; For the deicing pulse duration is specified initial valuation; Based on the thickness of deicing pulse duration and every kind of shape, the lip-deep Temperature Distribution of every kind of shape is carried out modeling; Determine to apply the freeze-off time again of every kind of shape after the deicing pulse; If the Temperature Distribution of model is then regulated the thickness of every kind of shape based on the Temperature Distribution of model not in the expectation tolerance; If determined freeze-off time is more then regulated the deicing pulse duration based on determined freeze-off time more not in the boundary that limits; And repeat modeling, definite and regulating step, in the boundary that Temperature Distribution is being expected in the tolerance and freeze-off time is limiting again.

In one embodiment, pulse electrothermal ice detachment apparatus comprises at least one the axially symmetrical complicated shape that is showed its feature by thickness distribution, and it is configured to produce uniform powerperunitarea to melt the boundary layer of ice.

Description of drawings

Fig. 1 shows according to an embodiment, comprises a dull and stereotyped exemplary pulse electro-thermal deicing (PETD) device;

Fig. 2 illustrates according to an embodiment, comprises a cylindrical exemplary PETD device;

Fig. 3 illustrates according to an embodiment, comprises an exemplary PETD device of bullet;

Fig. 4 illustrates according to an embodiment, comprises an exemplary PETD device of spheroid;

Fig. 5 illustrates according to an embodiment, comprises an exemplary PETD device of crescent moon body;

Fig. 6 illustrates the reproduction of the exemplary ice groove of the family expenses ice maker with axial symmetric shape;

Fig. 7 is the flow chart that illustrates an illustrative methods of the thickness optimization that makes complicated conductive shapes according to an embodiment, in the design of PETD system.

The specific embodiment

Pulse electrothermal deicing (PETD) can be used for by melting the boundary layer of icing at least " ice " being separated from object.As used in this application, term " ice " refers to have arbitrarily or do not have the freezing water of ice, snow, frost and other form of mixture." boundary layer of ice " refer to ice, near the thin layer of object.The thawing of the boundary layer of ice generally is enough to the major part (that is the not thawing part of ice) of ice is separated from object.The boundary layer of ice can have less than about 5 centimetres thickness, preferably has less than about 3 centimetres thickness, more preferably has the thickness between about 1 centimetre to 1 micron, most preferably has the thickness between about 1 millimeter to 1 micron.Should be appreciated that, apply the energy that is used for warming interface ice and also heated the part that object contacts with interface ice.It is desirable to, heat diffusion is interior less than about 5 centimetres distance to object and/or ice, preferably be diffused in object and/or the ice less than about 3 centimetres distance, more preferably be diffused into the distance between about 1 centimetre to 1 micron in object and/or the ice, most preferably be diffused into the distance between about 1 millimeter to 1 micron in object and/or the ice.

By the boundary layer of even thawing is provided, help making the energy that consumes during the PETD minimum.Thick especially thawing boundary layer removes ice temperature corresponding to higher, and shows as waste energy in ice detachment; That is, applied than the major part that will ice from the required energy more energy of object separation.For example, in ice maker, after deicing, " focus " that produces during the deicing needed to cool off before this point can recover ice making again; Owing to having melted the benefit that has reduced ice-making process than more appointed product.Excessively thin thawing boundary layer can be frozen into risk on the object again corresponding to the major part of ice before ice is removed.

For the energy that makes deicing consumes optimumly, utilize the device of PETD that the heating power of approximately constant density should be provided on each surface area of interface ice sheet.Yet, in the time will being had complicated shape, be difficult to realize the heating power of the constant density of each surface area by the object of deicing.As used in this application, " complicated shape " is meant that the part of object has the wall of one or more heterogeneity thickness.Complicated shape can be described by " thickness distribution ", and it has defined on certain distance the thickness of (for example, from object a bit to another point of object) wall.

The zone of heating of object shows its feature by electricalresistivity and thickness t.As the heating power W (W/m that applies per unit area ²) time, adopt following relational expression:

$W=E\&CenterDot;I_S=\frac{{\mathrm{<figure-callout\; id="2"\; label="E"\; filenames="A200780025089E00122.png,A200780025089E00142.png"\; state="\{\{state\}\}">E</figure-callout>}}^2\&CenterDot;t}{\mathrm{\&rho;}}=\frac{\mathrm{\&rho;}\&CenterDot;I_S^2}{t}$ Equation (1)

Wherein E is by current density I _SApplying and produce the electric-field intensity (V/m) of passing zone of heating (A/m).For the various piece at zone of heating keeps W constant, also adopt following relational expression:

$t=\frac{W\&CenterDot;\mathrm{\&rho;}}{{\mathrm{<figure-callout\; id="2"\; label="E"\; filenames="A200780025089E00122.png,A200780025089E00142.png"\; state="\{\{state\}\}">E</figure-callout>}}^2}$ Perhaps $t=\frac{\mathrm{\&rho;}\&CenterDot;I_S^2}{W}$ Equation (2)

Equation (2) is similar to, because it does not consider the dependence of the thermal capacitance of zone of heating to object thickness.Yet, equation (2) of great use because compare with the latent heat of the thermal capacitance, fabric of ice and the interface ice sheet that melts, thermal capacitance normally very little item in total PETD energy requirement.

Fig. 1 illustrates and comprises an exemplary PETD device 10 (1) of dull and stereotyped 40 (1).Fig. 1 may proportionally not draw.Power supply 20 (1) is connected to flat board 40 (1) by switch 30 (1), with plate 40 (1) power supplies to deicing.The length L and the thickness t of plate 40 (1) are shown in Figure 1.Power supply 20 (1) service voltage V wherein, the power W that is supplied with by power supply 20 (1) can be shown with the power meter of per unit area:

$W=\frac{{\mathrm{<figure-callout\; id="2"\; label="V"\; filenames="A200780025089E00122.png,A200780025089E00142.png"\; state="\{\{state\}\}">V</figure-callout>}}^2\&CenterDot;t}{\mathrm{\&rho;}\&CenterDot;{\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="A200780025089E00122.png,A200780025089E00142.png"\; state="\{\{state\}\}">L</figure-callout>}}^2}$ Equation (3)

Fig. 2 shows an exemplary PETD device 10 (2) that comprises cylinder 40 (2).Fig. 2 may proportionally not draw.Power supply 20 (2) is connected to cylinder 40 (2) by switch 30 (2), with cylinder 40 (2) power supplies to deicing.The length L and the thickness t of cylinder 40 (2) are shown in Figure 2.Power supply 20 (2) service voltage V wherein, the power W that power supply 20 (2) is supplied with can represent that wherein, equation (3) has been described the object with constant thickness with the power of the per unit area shown in the equation (3).

Fig. 3 illustrates an exemplary PETD device 10 (3) that comprises bullet 40 (3).Fig. 3 may proportionally not draw.Power supply 20 (3) connects by switch 30 (3), with bullet 40 (3) power supplies to deicing.The linear dimension x of bullet 40 (3), shown in Figure 3 about the angle θ and the thickness t of x axle.Notice that thickness t changes along with the position of the x axle of bullet 40 (3).Power supply 20 (3) service voltage V and electric current I wherein ₀, need provide the thickness t of power W constant, per unit area to be expressed as:

$t=\frac{\mathrm{\&rho;}\&CenterDot;{\mathrm{<figure-callout\; id="0"\; label="I"\; filenames="A200780025089E00141.png"\; state="\{\{state\}\}">I</figure-callout>}}_0^2}{4{\mathrm{\&pi;}}^2\&CenterDot;{\mathrm{<figure-callout\; id="2"\; label="x"\; filenames="A200780025089E00122.png,A200780025089E00142.png"\; state="\{\{state\}\}">x</figure-callout>}}^2\&CenterDot;{\tan }^2\left(\mathrm{\&theta;}\right)\&CenterDot;W}$ Equation (4)

Fig. 4 illustrates the cross section of an exemplary PETD device 10 (4) that comprises spheroid 40 (4).Fig. 4 may proportionally not draw.Power supply 20 (4) is connected to spheroid 40 (4) by switch 30 (4), with spheroid 40 (4) power supplies to deicing.The radius R of spheroid 40 (4), shown in Figure 4 about the angle θ and the thickness t of power supply axle.The thickness t of noting spheroid 40 (4) is along with angle θ changes.Power supply 20 (4) service voltage V and electric current I wherein ₀, need provide the thickness t of power W constant, per unit area to be expressed as:

$t=\frac{\mathrm{\&rho;}\&CenterDot;I_0^2}{4{\mathrm{\&pi;}}^2\&CenterDot;{\mathrm{<figure-callout\; id="2"\; label="R"\; filenames="A200780025089E00122.png,A200780025089E00142.png"\; state="\{\{state\}\}">R</figure-callout>}}^2\&CenterDot;{\sin }^2\left(\mathrm{\&theta;}\right)\&CenterDot;W}$ Equation (5)

Fig. 5 illustrates an exemplary PETD device 10 (5) that comprises crescent moon body 40 (5).Fig. 5 may proportionally not draw.Crescent moon body 40 (5) can be by producing about rotating shaft rotation straight line.This shape may be very useful, and for example, in ice maker, wherein, (1) uses the aqueous water filling shape, and cool off up to Water freezes into ice (2), (3) rotation make ice face down and (4) with the deicing PULSE HEATING so that ice and from shape, discharge.Power supply 20 (5) connects by switch 30 (5), with crescent moon body 40 (5) power supplies to deicing.The linear dimension x of crescent moon body 40 (5), shown in Figure 5 as the deviant R (x) and the thickness t of the function of the position on the x axle.The thickness t of noting shape 40 (5) is along with R (x) changes.If power supply 20 (5) service voltage V and electric current I can be shown ₀, then need to provide the thickness t of power W constant, per unit area to be expressed as:

$t=\frac{\mathrm{\&rho;}\&CenterDot;{\mathrm{<figure-callout\; id="0"\; label="I"\; filenames="A200780025089E00141.png"\; state="\{\{state\}\}">I</figure-callout>}}_0^2}{4{\mathrm{\&pi;}}^2\&CenterDot;R^2\left(x\right)\&CenterDot;W}$ Equation (6)

Can utilize several technology to make above-mentioned arbitrary shape 40, these technology include but not limited to the continuous application and the machining of die casting, injection molding, electrically-conducting paint or other coating.

Fig. 6 shows the reproduction of the ice groove 50 of family expenses ice maker.Utilize the ice maker of ice groove 50 to make by the composite (for example, the E5101 of CoolPolymers company) of heat conduction and conduction.The interior shape 40 (6) of ice groove 50 is axially symmetrical.In order to form ice, groove 50 is provided with supine inner shape 40 (6).The water filling slot 50 then.After water build-up ice, groove 50 rotated about 120 ° around its major axis, and applies 2 seconds pulse of electrical power by the copper busbar on the end 60 (1), 60 (2) that is set at groove 50.Electrical power equably heating tank 50 to the temperature more than the melting point of ice just in time, thereby melt the boundary layer of ice.Ice then and skid off from groove 50 and enter the collection container (not shown).Should be appreciated that groove 50 comprises complicated, variable thickness.Can utilize equation (6) calculated thickness, can adjust thickness at ad-hoc location (for example, corner) according to said method then.

Fig. 7 is the flow chart that illustrates an illustrative methods 100 of the thickness optimization that makes complicated conductive shapes in the design of PETD system.Should be appreciated that, some shown in Fig. 7 or can under the control of software instruction, carry out by computer in steps; Alternatively, some of Fig. 7 or institute can be carried out by the people in steps.In step 102, method 100 is each shape specified size and geometric type of deicing system, and the connection between the designated shape.In step 104, method 100 is specified the original depth setting for each shape; Being provided with like this can comprise fixed thickness (for example, shown in Fig. 1, Fig. 2 and equation (3)), and/or with the position of complicated shape and/or the thickness (for example, as Fig. 3 to Fig. 5, and equation (4) is to shown in the equation (6)) of angle variation.In step 106, specify deicing pulse parameter (for example, the voltage of supply or electric current), and the initial valuation in deicing pulse duration.In step 108, determine that with specific deicing pulse be the Temperature Distribution, temperature range of given shape acquisition and freeze-off time again.For example, can utilize the Finite Element Method modeling to come performing step 108, wherein, software kit (package) (for example, the FEMLAB3.1 of Comsol company) is used in the Finite Element Method modeling.Step 110 is to judge, it judges that temperature range is whether in specified tolerances.If temperature range outside specified tolerances (promptly, greater than the minimum temperature that produces by the deicing pulse and the expectation difference between the maximum temperature), then, in step 112 and step 114, shape is thickeied or thin respectively according to the model temperature of shape Tai Gao or too low whether.Step 116 is to judge.In step 116, freeze-off time again and specific minimum extreme value and maximum extreme value are compared.If freeze-off time is lacked very much (that is, being lower than specific minimum extreme value) again, then in step 118 lengthening deicing pulse; If freeze the time oversize (that is, being higher than specific maximum extreme value), then shorten the deicing pulse in step 120.Should be appreciated that, can also make amendment to the power parameter of deicing pulse (more or less power for example is provided), replace changing the duration of deicing pulse or as replenishing to duration of changing the deicing pulse.If changed shape thickness or freeze-off time again in step 112,114,118 and/or 120, then method is returned step 108; Otherwise method is finished and one group of thickness and deicing pulse parameter of optimizing of output in step 122.

Do not deviating under the prerequisite of the present invention, can carry out above-mentioned modification or other modification at the complicated shape and the correlation technique of the pulse electrothermal deicing device that the application is described.For example, the resistivity that can be inversely proportional to by the thickness of change and complicated shape provides the variation of heating.The principle that the application describes also is applicable to the setting (for example, the evaporation plate of refrigerating system or air-conditioning system) that may need regular deicing.Therefore should be noted that being included in the content shown in above-mentioned or the accompanying drawing should be interpreted as illustrative and meaning without limits.Claim tends to cover described all the general and specific features of the application, we can say that also whole explanations of the scope of this method and system fall into claim.

Claims (18)

1. a pulse electrothermal ice detachment apparatus comprises at least a complicated shape that is showed its feature by thickness distribution, and it is configured to produce uniform powerperunitarea, to melt the boundary layer of ice.

2. pulse electrothermal ice detachment apparatus as claimed in claim 1 also comprises power supply and switch, to make described complicated shape and described power connection and disconnection alternatively.

3. pulse electrothermal ice detachment apparatus as claimed in claim 1, wherein said complicated shape comprises bullet, and the thickness t of described bullet is according to equation: $t=\frac{\mathrm{\&rho;}\&CenterDot;I_0^2}{4{\mathrm{\&pi;}}^2\&CenterDot;x^2\&CenterDot;{\tan }^2\left(\mathrm{\&theta;}\right)\&CenterDot;W}$ Change, wherein said bullet is by showing its feature along the linear dimension x of x axle with respect to the angle θ of x axle, and described power supply is supplied with electric current I ₀, so that the power W of per unit area to be provided.

4. pulse electrothermal ice detachment apparatus as claimed in claim 1, wherein said complicated shape comprises spheroid, and the thickness t of described spheroid is according to equation: $t=\frac{\mathrm{\&rho;}\&CenterDot;I_0^2}{4{\mathrm{\&pi;}}^2\&CenterDot;R^2\&CenterDot;s{\mathrm{in}}^2\left(\mathrm{\&theta;}\right)\&CenterDot;W}$ Change, wherein said spheroid shows its feature by radius R with respect to the angle θ of the axis of power supply, and described power supply is supplied with electric current I ₀, so that the power W of per unit area to be provided.

5. pulse electrothermal ice detachment apparatus as claimed in claim 1, wherein said complicated shape comprises the crescent moon body, and the thickness t of described crescent moon body is according to equation: $t=\frac{\mathrm{\&rho;}\&CenterDot;I_0^2}{4{\mathrm{\&pi;}}^2\&CenterDot;R^2\left(x\right)\&CenterDot;W}$ Change, wherein said crescent moon body shows its feature by linear dimension x and deviant R (x), and described power supply is supplied with electric current I ₀, so that the power W of per unit area to be provided.

6. pulse electrothermal ice detachment apparatus as claimed in claim 1, described complicated shape is by one of them formation of the continuous application of die casting, injection molding, machining and conductive layer.

7. the method for the thickness of a complicated shape of optimizing the pulse electrothermal deicing system comprises:

Be the every kind of shape specified size and the geometry of pulse electrothermal deicing system, and specify the connectivity of described shape;

For every kind of shape is specified original depth;

For the deicing pulse duration is specified initial valuation;

Based on the thickness of described deicing pulse duration and every kind of shape, the lip-deep Temperature Distribution of every kind of shape is carried out modeling;

Determine to apply the freeze-off time again of every kind of shape after the deicing pulse;

If the Temperature Distribution of model is then regulated the thickness of every kind of shape based on the Temperature Distribution of described model not in the expectation tolerance;

If determined freeze-off time more in the boundary that limits, is not then regulated the described deicing pulse duration based on determined freeze-off time again; And

Repeat modeling, determine and regulating step, in the boundary that Temperature Distribution is being expected in the tolerance and freeze-off time is limiting again.

8. method as claimed in claim 7, the step of adjusting thickness comprises:

If described Temperature Distribution is higher than the expectation tolerance, then increase the thickness of described shape; And

If described Temperature Distribution is lower than the expectation tolerance, then reduce the thickness of described shape.

9. method as claimed in claim 7 is specified the step of original depth to be included as every kind of shape for every kind of shape and is specified fixing thickness.

10. method as claimed in claim 7 is specified the step of original depth for every kind of shape and is included as the thickness of every kind of shape specify variable.

11. method as claimed in claim 7, the step of regulating the described deicing pulse duration comprises: if determined freeze-off time again is higher than the extreme value of qualification, then shorten the described duration.

12. method as claimed in claim 7, the step of regulating the described deicing pulse duration comprises: if determined freeze-off time again is lower than the extreme value of qualification, then prolong the described duration.

13. a pulse electrothermal ice detachment apparatus comprises at least one the axially symmetrical complicated shape that is showed its feature by thickness distribution, it is configured to produce uniform powerperunitarea, to melt the boundary layer of ice.

14. pulse electrothermal ice detachment apparatus as claimed in claim 13 also comprises power supply and switch, with complicated shape and described power connection and the disconnection that makes described axial symmetry alternatively.

15. pulse electrothermal ice detachment apparatus as claimed in claim 13, the complicated shape of wherein said axial symmetry comprises bullet, and the thickness t of described bullet is according to equation: $t=\frac{\mathrm{\&rho;}\&CenterDot;I_0^2}{4{\mathrm{\&pi;}}^2\&CenterDot;x^2{\&CenterDot;\tan }^2\left(\mathrm{\&theta;}\right)\&CenterDot;W}$ Change, wherein said bullet is by showing its feature along the linear dimension x of x axle with respect to the angle θ of x axle, and described power supply is supplied with electric current I ₀, so that the power W of per unit area to be provided.

16. pulse electrothermal ice detachment apparatus as claimed in claim 13, wherein said axial complicated shape comprises spheroid, and the thickness t of described spheroid is according to equation: $t=\frac{\mathrm{\&rho;}\&CenterDot;I_0^2}{4{\mathrm{\&pi;}}^2\&CenterDot;R^2{\&CenterDot;\sin }^2\left(\mathrm{\&theta;}\right)\&CenterDot;W}$ Change, wherein said spheroid shows its feature by radius R with respect to the angle θ of the axis of power supply, and described power supply is supplied with electric current I ₀, so that the power W of per unit area to be provided.

17. pulse electrothermal ice detachment apparatus as claimed in claim 13, the complicated shape of wherein said axial symmetry comprises the crescent moon body, and the thickness t of described crescent moon body is according to equation: $t=\frac{\mathrm{\&rho;}\&CenterDot;I_0^2}{4{\mathrm{\&pi;}}^2\&CenterDot;R^2\left(x\right)\&CenterDot;W}$ Change, wherein said crescent moon body shows its feature by linear dimension x and deviant R (x), and described power supply is supplied with electric current I ₀, so that the power W of per unit area to be provided.

18. pulse electrothermal ice detachment apparatus as claimed in claim 13, the complicated shape of described axial symmetry is by one of them formation of the continuous application of die casting, injection molding, machining and conductive layer.

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