WO2004019065A1

WO2004019065A1 - Sond for atmospheric measurements

Info

Publication number: WO2004019065A1
Application number: PCT/FI2003/000612
Authority: WO
Inventors: Hans-Karl Von Bagh; Atte Edward Pihlava
Original assignee: Vaisala Oyj
Priority date: 2002-08-20
Filing date: 2003-08-19
Publication date: 2004-03-04
Also published as: AU2003255541A1; FI20021500A0

Abstract

The prior art includes, for example meteorological and radiosondes, which are used to measure the prevailing atmospheric conditions. This publication discloses a sonde for sondes and a sonde. When a sonde rises to the cold layers of the atmosphere, its temperature drops to about -50 °C. The batteries used in the sonde must be able to supply the sonde's electronics with the power they require, even in such conditions. The invention exploits the fact that the soundings carried out using sondes are of a quite short duration. According to the invention, the cooling of the batteries (2) is slowed and delayed by bringing them into thermal contact with a phase-transition substance (3). The phase-transition substance is a substance in which a phase transition takes place when the temperature changes from the temperature of the storage of the arrangement or sonde to the temperature of the measuring environment. The phase-transition substance (3) can be, for example, water, which prevents the temperature of the battery (2) from dropping below 0 °C, until the water has frozen.

Description

Sond for atmospheric measurements

The present invention relates to a sonde according to the preamble of Claim 1 and a sonde according to the preamble of Claim 12.

Battery arrangements of this kind are used, for example, in radiosondes and meteorological sondes, which are used to perform measurements in the atmosphere. Sondes of this kind are, in turn, used for making atmospheric soundings and measuring the prevailing conditions.

The prior art includes, for example, radiosondes according to publication GB 1 459934. The sondes are generally meteorological sondes, which are used to measure prevailing atmospheric conditions, such as temperature, air pressure, humidity, wind direction and speed, and/or the amounts of various gases, such as ozone. Sondes can be used to perform measurements at different heights in the atmosphere. The sondes, i.e. sounding apparatuses, typically include a measurement device part, which comprises the measuring equipment, and a buoyant balloon, which comprises a plastic balloon filled with hydrogen or helium. When the sonde is launched, the measurement equipment is set to be ready to make measurements and the balloon is filled with gas. The buoyancy of the balloon causes the sonde to rise in the atmosphere, so that the measuring equipment can make measurements at different heights in the atmosphere. The sonde typically sends the measurement data over a radio link to a central unit. The prior art also includes rocket sondes, in which the ascent is powered by a rocket engine and the measurements take place during the descent, which is slowed by a parachute. The prior art also includes sondes dropped from aircraft, the descent of which is slowed by a parachute, balloon, or a combination of both. In addition, the prior art also includes sondes, which do not send the measurement data over a radio link, the data being transmitted instead in some other manner.

Sondes thus generally include measurement electronic equipment, radio electronic equipment, and possible other electronic equipment. In this publication, the term electronic equipment refers to the aforesaid electronic equipment, or to parts of it. Sondes are mainly single-use. Because sondes are sent at relatively frequent intervals, for example, to monitor weather conditions, it is also desired for sondes to be easy to use and quick to launch, as well as being as economically priced as possible. Sondes are made as compact and light as possible, to permit the use of the smallest possible balloon and the least possible buoyancy gas. Compactness and lightness are also advantageous in terms of storage.

The electronics in sondes are typically powered by cell batteries. Because sondes are also used in the cold layers of the atmosphere, the internal temperature of the sonde can drop to a temperature of, for example, -50°C. The power output of cell batteries typically weakens as the temperature drops, a point that must be taken into account when designing power supplies for sondes.

This problem can be resolved in several different ways. One way is to select a type of battery that also operates at low temperatures. Such battery types include, for example, nickel-cadmium, lithium-iron sulfide, and lithium-manganese dioxide batteries, the power output of which is quite good, even at a temperature of about -40°C. A drawback with nickel-cadmium batteries is, however, their poor power density (Wh/kg), which is an undesirable feature for components used in sondes. The power density of lithium-iron sulfide and lithium-manganese dioxide batteries is, on the other hand, excellent, but this type of battery is expensive.

A more usual alternative is to use water-activated silver chloride batteries, which are activated by adding water or a salt solution to the battery before launching the sonde. The battery activates about 1 - 5 minutes after the addition of the water. This type of battery has the drawbacks of a high price and poor usability due to the activation. The person launching the sonde must add water to the battery and then wait until the battery activates. In addition, the use of this type of battery means that the sonde must be designed to allow water to be added to the battery through a filler opening.

In some solutions, the requisite power output is ensured by keeping the temperature of the battery within the limits of the operating temperature, in one way or another. If a type of battery is used, in which the voltage is formed with the aid of an exothermal chemical reaction, the temperature can be maintained by continuously loading the battery at a suitable output. The operating principle of nickel-cadmium batteries, for example, is exothermal. However, the power requirement of the electronics of sondes is not necessarily great enough for the power consumption to keep the battery at its operating temperature due to the exothermal process. A circuit that maintains a suitable minimum load must therefore be connected to the battery. The drawback of such a solution is that the size, weight, and complexity of the sonde are increased by the additional electronics. In addition, the battery must be dimensioned so that its power output is sufficient both for the measurement electronics and for maintaining its own temperature. The battery will then naturally be larger and heavier, which is not desirable.

A separate temperature-controlled heating circuit can also be used to keep the battery within the limits of the operating temperature. Such a solution is generally implemented by using an alkali battery as the main power supply and an exothermal battery as the heating-circuit power supply. The operating principle of alkali batteries is not exothermal and the lower limit of their operating temperature is about -20°C, so that they are not as such suitable for use in sondes. On the other hand, the other properties of alkali batteries are suitable for use in sondes, as the power density of an alkali battery is quite high and its price is quite low. An exothermal battery can be used as the power supply of the heating circuit, thus ensuring the power supply to the heating circuit. Such an apparatus is disclosed in, for example, publication US 5,599,636.

A solution, in which a phase-transition substance is used in connection with accumulators for recovering or discharging heat, is known from WO publication 01/65626. A sonde embodiment is not disclosed.

Solutions based on a phase-transition substance and implemented in automotive accumulators are disclosed in, among others, US patent 5449571, DE publication 0588004, and US application number 2001/033961. These solutions are heavy and therefore are not suitable for sonde use. A drawback in the prior art is that relatively complex, heavy, space-consuming, and/or expensive arrangements must be used in sondes, in order to ensure a sufficient power supply. As stated above, these properties are not desirable in sondes.

In addition, when the temperature changes, the voltage produced by the battery changes. This too is a drawback in radiosondes, as the transmission frequency of the sonde's radio transmitter may depend on the input voltage. Thus the sonde's radio transmission frequency will vary according to the temperature. The radio device receiving the measurement data will therefore have to be able to receive radio signals with a varying carrier frequency. In some solutions of the prior art, this problem is solved by using a suitable circuit to equalize the battery's voltage output. This has the drawbacks of additional cost and weight due to the circuit. In addition, the circuit itself consumes power.

The invention is intended to eliminate the defects of the state of the art disclosed above and for this purpose create an entirely new type of sonde. The intention is thus to create a battery arrangement and a sonde that are compacter, simpler, cheaper, and possible also lighter than the prior art.

The invention is based on the change in the temperature of the battery being slowed and delayed by bringing the battery in thermal contact with a substance, in which a phase transition takes place when the temperature of the battery arrangement/sonde changes from the storage temperature to the temperature of the measuring environment (hereinafter a phase-transition substance). The energy released in the phase transition is used to slow and delay the cooling of the battery, so that it will remain at its operating temperature. The invention exploits the fact that soundings made with a sonde last for only about 130 minutes. Due to the short duration of the sounding, it is sufficient for the battery to be kept at its operating temperature for the duration of the sounding, by slowing and delaying the cooling of the phase-transition substance. If the battery is in thermal contact with a phase-transition substance, the temperature of the phase-transition substance and the battery will drop below, for example, the melting point of the phase- transition substance only once the phase-transition substance has changed entirely from a liquid to a solid. During the phase transition, the temperature of the phase-transition substance and the battery remains essentially at the temperature of the melting point of the phase-transition substance.

In preferred embodiments, the phase-transition substance used is water, a salt solution, or a mixture of water and an alcohol. If water, for example, is used, the temperature of the battery will remain at a temperature of about 0°C, until the water has frozen. When using a salt solution, the corresponding temperature will be slightly lower. When using a water-alcohol mixture, the temperature will depend on the mixture ration and can be, for example, -15°C. The effect of the atmospheric pressure in the measuring environment should be taken into account, when designing the phase-transition point.

At its simplest, a solution according to the invention is a water bag in contact with the batteries.

More specifically, the sonde according to the invention is characterized by what is stated in the characterizing portion of Claim 1. More specifically, the sonde according to the invention is characterized by what is stated in the characterizing portion of Claim 12.

Considerable advantages are gained with the aid of the invention.

For example, with the aid of the invention alkali batteries can be used in sondes, thus reducing the costs of manufacturing sondes. In addition, the usability of the sondes will improve, as the launcher will not need to activate the battery by adding water and will not need to wait for the battery to activate. The design and manufacture of sondes will also be facilitated, as the location of the batteries inside the sonde can be selected more freely, as the operation of adding water need not be taken into account.

In addition, the temperature of the battery will remain more even during the sounding, so that the voltage produced by the batteries will remain more even than in solutions according to the prior art. Thus, the frequency of the sonde's radio transmitter will be better held within the range of the desired frequency and the transmitted radio signal will be easier to receive. With the aid of the invention, the operating time of alkali batteries, for example, can be extended by about 40 minutes.

In the following, the invention is examined with the aid of examples and with reference to the accompanying drawings.

Figure 1 shows a vertical cross-section of one sonde battery arrangement according to the invention.

Figure 2 shows a horizontal cross-section of the battery arrangement corresponding to Figure 1.

Figure 3 shows a horizontal cross-section of a second sonde battery arrangement according to the invention.

The battery arrangements according to Figures 1 - 3 include a casing 1 made of a thermally insulating material, the batteries 2, a phase-transition substance 3, and a thermally conductive substance 4.

The casing 1 can be manufactured from, for example, expanded polystyrene (EPS), i.e. so-called styrox, or from some other material with a good thermal-insulation capacity.

The use of a casing is not absolutely necessary, but does have obvious benefits. Thanks to the insulating casing, the temperatures of the batteries 2 and the phase-transition substance 3 remain closer to each other, as the casing thermally insulates the internal components of the battery arrangement from the environment. In addition, the insulating casing slows the cooling of the batteries even further.

The batteries used can be, for example, commercially available standard alkali batteries, such as 9V batteries, or 1.5V AA or AAA batteries. Figures 1 and 2 show two 9V batteries and Figure 3 seven 1.5V AA or AAA batteries. Other types of batteries, such as dry-cell batteries, can also be used. The batteries can be either primary, i.e. disposable single-use batteries, or secondary batteries, e.g. accumulators, which can be recharged after use.

The phase-transition substance used can be, for example, water, a salt solution, a mixture of water and some alcohol, or any other substance whatever, in which a phase transition, i.e. a change of state, takes place at a suitable temperature, for example between +10°C and -15°C. The term phase transition refers to the change of a substance from a liquid to a solid, from a gas to a liquid, or from a sublimated gas to a solid. The term phase- transition temperate refers to the temperature at which the phase transition takes place. The phase-transition substance can be enclosed in, for example, a bag or a reservoir, the walls of which are thin and/or conduct heat well. If water is used as the phase-transition substance, the typical amount of water is 15 - 40 grammes.

The thermally conductive substance 4 can be, for example, a thermally conductive paste, grease, or adhesive. Aluminium or copper foil, or any other substance whatever that conducts heat well can also be used as the thermally conductive substance 4. The thermally conductive substance 4 is arranged between the batteries 2 and the phase- transition substance 3, so that the thermally conductive substance 4 forms a thermal connection between the batteries 2 and the phase-transition substance 3. The empty space between the walls of the casing 1, the batteries 2, and the phase-transition substance reservoir 3 can be, for example, completely filled with the thermally conductive substance 4. Naturally, inside the casing there should also be connections, by means of which power is supplied from the batteries 2 to the electronics of the sonde. If the thermally conductive substance 4 is electrically conductive, the terminals of the batteries should be insulated electrically from the thermally conductive substance.

Embodiments, differing from those disclosed above, can also be contemplated within the scope of the invention.

Naturally, any batteries at all that are suitable for the purpose in question can be used in the battery arrangement. For example, a water-activated battery can be used, in which case water can be added before the sonde is launched, in order both to activate the battery and to act as the phase-transition substance. The battery arrangement can also be formed in such a way that the phase-transition substance completely surrounds the batteries. For example, there can be a jacket around the batteries, which contains the phase-transition substance. In this case, the thermally conductive substance can be omitted from the arrangement.

The battery arrangement according to the invention can also be implemented in such a way that there is no thermally conductive substance 4 between the battery 2 and the phase-transition substance 3. The battery can be e.g., totally or partly submerged in the phase-transition substance.. In this case, if the phase-transition substance is electrically conductive and in contact with the terminals, the battery terminals should be electrically insulated from the phase-transition substance. On the other hand, there can also be a thin layer of a substance with poor thermal conductivity between the battery 2 and the phase- transition substance 3.

The invention can also be implemented in such a way that there are several phase- transition substances. One of the phase-transition substances can be, for example, water, and the other phase-transition substance a mixture of water and some alcohol, which mixture has a freezing point of -15°C. The mixture of water and alcohol can be set in a jacket around the battery and the water correspondingly in another, outer, jacket around the mixture of water and alcohol. In that case, the water will freeze first and the temperature of the water-alcohol mixture will drop below 0°C only once the mixture of water and alcohol has essentially frozen entirely.

Within the scope of the invention, it is also possible to contemplate a solution, in which the cooling of some other power supply, such as a solar panel or a fuel cell is delayed and slowed in the manner according to the invention. In the case of a fuel cell, it is possible for the phase-transition substance to also form the fuel for the fuel cell. In such a case, the phase-transition substance can be, for instance, methanol or some other alcohol.

For example, the following substances, or mixtures of them, can be used as phase- transition substances: hexadecyne C₁₆H₃ , cyclohexane CβΑn, benzene C^k, butane C+Hio, methyl-propane CφHio, 1,3-butadiene C₄H₆, tetrachlorizated methane CCI₄, chloroethene C₂H₃CI, 1,2-ethanediole, i.e. glycol, 1,2,3-propanenitriole, i.e. glycerol C₃H₅(OH)3. benzylalcohol C₆H₅CH₂OH, dimethylether (CH₃)₂O, methylamine CH₃NH₂, dimethylamine (CH₃)₂NH, trimethylamine (CH₃)₃N, phenylamine CβHsNBfe, methanal, i.e. formaldehyde HCHO, methanic acid, i.e. formic acid HCOOH, ethanic acid, i.e. acetic acid CH3COOH, propanic acid CH₃CH₂COOH, 9-octadecenic acid C₁₇H₃₃COOH, 9,2-octadecenic acid C₁ H₃iCOOH, 2-hydroxypropanic acid, i.e. lactic acid CH3CHOHCOOH. Mixtures or solutions of the aforementioned substances, such as water or ether solutions can also be used as phase-transition substances. Other substances than those referred to above can also be used as phase-transition substances.

The phase transition of the phase-transition substance can also be adjusted to a suitable temperature, by encapsulating the phase-transition substance in a suitable pressure vessel. The freezing point of water can, for example, be reduced by enclosing water in a pressurized vessel. Correspondingly, for example, the boiling point, i.e. the condensing temperature, of alcohol can be reduced by enclosing alcohol vapour in a vacuum vessel.

Within the scope of the invention, it is also possible to contemplate an embodiment, in which the phase-transition substance is added to the sonde only at the launch stage. The phase-transition substance can be in a reservoir or bag, which is, for example, partly open at the top.

When rising in the atmosphere, meteorological and radiosondes are exposed not only to cold, but also to strong sunlight, which can heat the sonde. The invention can also be applied in such a way that, with the aid of a phase-transition substance, the heating of the sonde or its electronics is slowed or delayed. This brings the advantages of, for example, improving the stability of frequency-precise crystals in the electronics, due to the more even temperature. In such embodiments, the phase-transition substance used can be, for example diethyl ether (C₂H5)₂O, which has a boiling point of 35EC, or ethanal, i.e. acetaldehyde CH3CHO, which has a boiling point of 24EC. During the slowing or delaying of the heating of the sonde, a phase transition, from, for example, a liquid to a gas, a solid to a liquid, or sublimation from a solid to a gas, takes place in the phase- transition substance.

One embodiment according to the invention is a sonde, which includes a measuring equipment part, which is arranged to measure the prevailing atmospheric conditions, with the aid of electrical, electrochemical, electrothermal, electromagnetic, electroradiological, and/or electromechanical sensors, the power supply of which measuring equipment part is arranged to be at least one battery 2, which battery is arranged in thermal contact with a phase-transition substance 3, such as water, a salt solution, or a mixture of alcohol and water. The sonde can also include a GPS (Global Positioning System) receiver, which is arranged to determine the location and altitude of the sonde in the atmosphere, and the speed and direction of the wind and/or the sonde. In the embodiment, the phase-transition substance is enclosed in a phase-transition- substance reservoir or bag. In the embodiment, the battery 2 and the phase-transition substance 3 are brought into thermal contact, by arranging a continuous part of thermally conductive substance 4 to be in contact with the battery 2 and the phase-transition substance 3, or the phase-transition-substance reservoir or bag. In the embodiment, a radio transmitter part, which is arranged to transmit the measurement data defined by the measuring equipment part over a radio link, is arranged to be connected to the measuring equipment part of the sonde. In the embodiment, a balloon or rocket is arranged in connection with the sonde, with the aid of which the sonde is made to rise in the atmosphere. In the embodiment, a parachute part is arranged in connection with the sonde, which is arranged to open a parachute that will slow the descent of the sonde.

Claims

Claims:

1. A sonde intended for atmospheric research, which includes at least one battery (2) located in a thermally insulating casing (1) characterized in that the sonde includes a phase-transition substance (3) located in a reservoir or bag inside the casing (1), which is in thermal contact with the batteries (2), in order to slow and/or delay the cooling of the batteries (2).

2. A sonde according to Claim 1, characterized in that the phase-transition substance (3) is at least principally water and is enclosed in a reservoir or bag.

3. A sonde according to Claim 1 or 2, characterized in that it is applied to a meteorological, radio, or other sonde.

4. A sonde according to Claim 1 or 2 or 3, characterized in that the battery (2) or batteries (2) are alkali batteries or dry-cell batteries.

5. A sonde according to any of Claims 1 - 4, characterized in that the phase-transition substance (3) is water, a salt solution, a mixture of some alcohol and water, or a solution or mixture of some organic substance.

6. A sonde according to any of Claims 1 - 5, characterized in that a thermal connection created between the batteries (2) and the phase-transition substance (3) with the aid of a thermally conducting substance (4), for example, a thermally conductive paste or adhesive or aluminium or copper foil.

7. A sonde according to any of Claims 1 - 6, characterized in that the batteries (2) and/or the phase-transition substance (3) are at least partly enclosed in a thermally insulating casing (1).

8. A sonde according to any of Claims 1 - 7, characterized in that the sonde includes several different phase-transition substances, which have different phase-transition temperatures.

9. A sonde according to any of Claims 1 - 8, characterized in that the battery (2) or batteries (2) are submerged at least partly in the phase-transition substance (4) or that the phase-transition substance (4) at least partly surrounds the batteries (2).

10. A sonde according to Claim 9, characterized in that the battery (2) or batteries (2) are at least partly surrounded by several different layers or jackets of the phase-transition substance.

11. A sonde according to any of Claims 1 - 10, characterized in that the phase- transition substance is a substance, in which a phase transition takes place when the temperature of the sonde changes from its storage temperature to the temperature of its operating or measurement environment, or to a temperature due to the operating or measuring conditions.

12. A sonde, such as a meteorological or radiosonde, characterized in that it includes a sonde and/or phase-transition substance (3) according to any of Claims 1 - 11, which phase-transition substance is in thermal contact with the electronics of the sonde, in order to slow and/or delay the heating of the electronics.

13. A sonde according to Claim 11 or 12, characterized in that the phase-transition substance (3) is a solution or mixture of some organic substance.

14. A sonde according to any of Claims 10 - 13, characterized in that a thermal connection is created between the electronics and the phase-transition substance (3) with the aid of a thermally conductive substance (4), for example, a thermally conductive paste or adhesive or aluminium or copper foil.

15. A sonde according to any of Claims 12 - 14, characterized in that the electronics and/or the phase-transition substance (3) are at least partly enclosed in a thermally insulating casing (1).

16. A sonde according to any of Claims 12 - 15, characterized in that the sonde includes several different phase-transition substances, which have different phase- transition temperatures.

17. A sonde according to any of Claims 12 - 16, characterized in that the electronics are at least partly submerged in the phase-transition substance (3) or that the phase-transition substance (3) at least partly surrounds the electronics.

18. A sonde according to Claim 16 or 17, characterized in that the electronics are at least partly surrounded by several separate phase-transition-substance layers or jackets.

19. A sonde according to any of the above Claims, characterized in that the phase- transition substance is a substance, in which a phase transition occurs when the temperature of the sonde changes from the storage temperature to the temperature of the operating or measurement environment, or to a temperature due to the operating or measurement conditions.