DE102009001997B4 - Absorption chiller with aqueous refrigerant - Google Patents

Abstract

Method for generating cold by means of an absorption refrigerator with - an evaporator (1) for a water-containing refrigerant, - an absorber (2) in which the evaporated refrigerant is absorbed in a solvent, - a desorber (4) in which the absorbed refrigerant is expelled from the solvent with the supply of heat, characterized in that the refrigerant vapor expelled from the solvent is fed to a resorber (27), a solution of refrigerant and antifreeze in which the refrigerant vapor is absorbed is received in the resorber (27), and wherein the solution of refrigerant and antifreeze is passed into the evaporator (1) to evaporate the refrigerant from the solution.

Description

The method described here and the arrangement described here relate to an innovation in the field of absorption refrigerating machines.

The present patent application is the subject of a registration series in which several inventions are described on an absorption refrigeration machine and its operating method and use.

Absorption refrigerators differ from conventional compression refrigerators essentially in that the cold is generated not by supplying mechanical work but by supplying thermal energy. In the compression refrigeration machine, a refrigerant for generating cold is vaporized in an evaporator, then compressed by a compressor, then cooled in a heat exchanger (heat exchanger) and liquefied before being returned to the evaporator.

An absorption chiller is shown schematically in FIG 1 shown. In the absorption chiller that is in the evaporator 1 vaporized refrigerant is not supplied to a compressor, but an absorber 2 in which it is absorbed by a solvent. For evaporation, energy is extracted from an external coolant at a low temperature level. This coolant provides the useful cold.

The solvent in the absorber 2 is at the pressure level of the refrigerant. That in the absorber 2 refrigerant-enriched solvent is then passed through a solvent pump 3 compacted and a desorber 4 fed. The compaction requires little mechanical work, since the solvent is liquid and therefore incompressible. In the desorber 4 Heat is supplied to the solution of solvent and refrigerant to drive the refrigerant out of the solvent. The expelled refrigerant becomes a condenser 5 fed. desorber 4 and capacitor 5 are at a high pressure level. From the condenser 5 from the refrigerant flows due to the existing pressure difference through an expansion throttle 6 back to the evaporator 1 ,

The poor in refrigerant and the heat supply hot solvent from the desorber 4 flows through a regenerative heat exchanger 8th in which it is that of the absorber 2 preheated cool solvent with a high refrigerant content preheated. It cools it off and flows it over a relaxation throttle 7 back to the absorber 2 ,

Absorption refrigerators typically use ammonia as a refrigerant when temperatures below the freezing point of water are to be achieved. The solvent in this case is water. Absorption chillers with water as the refrigerant usually cool down to 4 ° C, since ice formation at lower temperatures is a natural limit. Absorption chillers with the refrigerant water usually use as solvent aqueous salt solutions (lithium bromide). Such chillers go, for example, from the patents DE 103 47 497 B4 . DE 103 47 498 B4 and DE 103 53 058 B4 the applicant known.

For the refrigerant water can be used as solvent but also acids such. As sulfuric acid or alkali mixtures or alkalis such. B. caustic soda or Laugengemische be used. To high temperature differences between Nutzkältetemperaturniveau (evaporator 1 ) and waste heat temperature level (absorber 2 ), the solvents must be used in a correspondingly highly concentrated manner, ie the distance to the crystallization boundary is very small. On the other hand, the crystallization - and thus the transition of the solvent in the solid state of aggregation - must be avoided, otherwise the solvent is no longer pumpable and the system can no longer be operated. The crystallization of the solvent is therefore to be avoided in all operating conditions. Especially from the desorber, also called cooker or expeller, originating solution that is depleted of refrigerant, is the subsequent cooling in the regenerative heat exchanger 8th (often called heat exchangers) endangered, since it usually has the highest concentration value.

• • einem Verdampfer für ein wasserhaltiges Kältemittel,
• • einem Absorber, in dem das verdampfte Kältemittel in einem Lösungsmittel absorbiert wird,
• • einem Desorber, in dem das absorbierte Kältemittel aus dem Lösungsmittel unter Wärmezufuhr ausgetrieben wird.

The invention relates to a method for generating cold by means of an absorption chiller with

• An evaporator for a water-containing refrigerant,
• An absorber in which the vaporized refrigerant is absorbed in a solvent,
• • a desorber, in which the absorbed refrigerant is expelled from the solvent under heat.

It further relates to a corresponding absorption chiller.

In the field of absorption chillers, two different types of refrigeration can be considered as prior art, namely water-based and ammonia-based machines. For the refrigerant water are a variety of solvents ( Solvents are z. As lithium bromide, sulfuric acid, sodium hydroxide solution) have been proposed and tested.

A disadvantage of ammonia is its toxicity and combustibility. In addition, it is relatively unsuitable to utilize waste heat potential low temperature (<100 ° C). Advantageous is the trouble-free reaching of temperatures below 0 ° C and a favorable vapor pressure behavior.

The refrigerant water is unproblematic in every respect and has good thermodynamic properties. The major disadvantage of the refrigerant water is its limitation to useful cold temperature levels greater than 0 ° C, since the freezing point problem does not allow lower temperatures. Occasionally it has been proposed to achieve a freezing point reduction by adding salts or the like into the evaporator (eg. EP1391668 ). However, this does not make sense, since pure water is obtained in the condenser and then expanded under icing in the evaporator. A safe ice-free continuous operation can not be achieved.

The patents described above DE 103 47 497 B4 . DE 103 47 498 B4 and DE 103 53 058 B4 The applicant describes a water-powered absorption chiller that should reach temperatures below freezing. The proposals described here are problematic in practice. The use of a vapor compressor according to DE 103 53 058 B4, for example, makes the absorption process more of a compression process. This means that predominantly high-quality electrical energy has to be used for mechanical compression in order to generate refrigeration, and it is not possible to use the waste heat from the oven or any other device for producing refrigeration.

The publication DE 10 2007 062 343 A1 describes a water-lithium bromide resorption refrigeration process with cooling temperatures around and below 0 ° C, typically -4 ° C. Here it is proposed to pass the expelled water vapor in a condenser, there to condense and then supply the condensed water to the absorption loop, where it is absorbed by mixed absorption, the lithium bromide solution is guided in the cooling part only through the desorber.

An alternative absorption refrigeration machine is now to be created which can reliably produce temperatures far below the freezing point of water with an aqueous refrigerant.

This object is achieved in that the refrigerant vapor expelled from the solvent is supplied to a resorber, in which the refrigerant vapor is absorbed in a solution of refrigerant and antifreeze, and that the solution of refrigerant and antifreeze is supplied to the evaporator, from which the refrigerant evaporates becomes.

By introducing an additional "absorption cycle" the difficulties mentioned can be overcome. While in Ammoniakbasierten chillers by using a Resorptionskreislaufs the high pressure in the desorber can be effectively lowered, in water-based chillers - which are operated in vacuum - absorption cycles have not been used.

Due to the additional absorption cycle, the freezing point of the refrigerant can now be lowered. The evaporator is therefore not pure water, but an aqueous solution - with a correspondingly lower freezing - fed. Also in the absorber is a solvent with reduced freezing point, so that the water vapor can be absorbed even at temperatures well below 0 ° C without ice formation.

As mentioned above, is in 1 a conventional absorption chiller with water as solvent shown. That water gets in the evaporator 1 evaporates in a vacuum and cools down. The water vapor is in the absorber 2 absorbed and then to the desorber 4 (also called cooker or expeller pumped). Here it is boiled out of the solvent and flows to the condenser 5 where it condenses and returns to the evaporator as liquid water 1 is supplied.

In contrast, the absorption chiller is equipped with an additional absorption cycle. In this case, the long-known mixture of sodium hydroxide and potassium hydroxide solution is preferably used instead of lithium bromide for solvents of water-based absorption chillers. This is characterized by a stronger vapor pressure reduction, so that useful cooling temperatures of -10 ° C and below can be achieved. It also significantly reduces the freezing point of the water in sufficient concentration.

In this process variant, the evaporator can be described more correctly as a degasser, since it does not completely evaporate the aqueous solution, but only evaporates water out of this solution, thereby increasing the concentration of the aqueous solution in the resorber / evaporator cycle.

In addition to the circumvention of the freezing point problem arises as a further advantage of this system variant, the possibility of concentration shift. In other words, by transferring solution from the absorber / desorber, Circulation in the resorber / evaporator - cycle the freezing point can be largely adapted to the respective requirements (summer or winter operation). This allows flexible response to changes in environmental conditions, eg. For example, when conceivable operation as a heat pump, in which the ambient temperature is below -10 ° C (TUmg <-10 ° C). The reverse approach, the transfer of solution from the resorber / evaporator circuit in the absorber / desorber - cycle, may be useful if the solution concentration (and thus the possible temperature deviation) should be increased briefly. However, it is always a prerequisite that both the antifreeze and the absorbent solution consist of the same mixture of substances, namely soda / potassium hydroxide solution.

The refrigerant may flow in the illustrated resorber-evaporator circuit in a first line from the low-temperature evaporator to the resorber and flow in a second line from the resorber to the evaporator. Both lines can be supplied to a heat exchanger in which the refrigerant flow originating from the evaporator is heated on the way to the resorber and the refrigerant flow originating from the resorber is cooled on the way to the evaporator.

A corresponding heat exchanger can also be present in the absorber / desorber circuit so that the solvent originating from the absorber is brought to the high temperature of the desorber (also called cooker or expeller).

If one has knowledge of the currently present concentration, an inadmissible approach or exceeding of the crystallization limit can be avoided by means of various control interventions.

Various measures for calculating the solution concentration have been developed. For example, the solution concentration can be calculated from the measured temperatures at the digester and the pressure in the container (eg. PCT / EP2005 / 008717 or US 6,637,221 B1 ).

Likewise, in the case of "normal" absorption chillers, ie those working with pure refrigerant, it is possible to deduce the concentration of the solution in the absorber / desorber cycle from the level of the refrigerant in the evaporator. Various limit switches or level sensors can be used for this purpose (eg CA 2216257 ).

A disadvantage of the calculation of the solution concentration of temperature and pressure data, or the conclusion on the concentration of the level of the refrigerant in the evaporator is the relatively large inaccuracy of these indirect methods. This inaccuracy is taken into account by a correspondingly large safety distance from the crystallization curve.

Another object, which is solved by the novel absorption chiller, is to ensure a more precise adherence to a high solvent concentration below the crystallization limit.

• • einen Hohlraum, in dem Flüssigkeit und ein in die Flüssigkeit eingetauchtes Senkelement, insbesondere eine Senkspindel, aufgenommen sind,
• • eine Sensoranordnung zum Erfassen der Bewegung des Senkelements.

For this purpose, the device for determining the concentration of at least one of the liquids has the following:

• A cavity in which liquid and a sinking element immersed in the liquid, in particular a sinking spindle, are accommodated,
• A sensor arrangement for detecting the movement of the lowering element.

In other words, a measuring spindle is proposed whose movement can be detected automatically in order to be able to determine exactly the concentration of the measured liquid, in particular the solvent of the absorption chiller.

This new technology is characterized by a number of advantages. The basic idea is the almost direct measurement of the solution concentration. A particularly cost-effective and at the same time very reliable and accurate measurement of the density, from which the solution concentration can be easily calculated at a known temperature, is made possible by means of sealing spindles. It is therefore proposed the use of a sealing spindle for direct and automatic concentration determination.

• • Magnet und Magnetschalter;
• • Spule und Spulenkern;
• • inkrementale Messskala und eine optische Erfassungsvorrichtung zum Lesen der Messskala.

The sensor arrangement may comprise at least one of the following enumerated pairs of cooperating elements for measuring the movement of the lowering element, one of the elements of the pair being attached to the lowering element:

• • magnet and magnetic switch;
• • coil and spool core;
• • incremental measuring scale and an optical detection device for reading the measuring scale.

In practice, the arrangement for measuring the movement of the lowering element can be designed such that the signal representing the movement of the lowering element is transmitted through a closed wall, in particular made of stainless steel. In particular, in the area of the evaporator of the refrigerant prevails in an absorption refrigerator with water-based refrigerant, a vacuum when very low temperatures are to be reached far below the freezing point of water. at Temperatures in the range of -10 ° C, the evaporation pressure is of the order of 2 mbar. To ensure such low pressures within the cavity, it makes sense from this closed, z. B. welded walls made of high-strength materials such as stainless steel. The measuring means or signal transmission means can transmit the signal representing the movement through the wall to the outside. If permanent magnets are used inside the cavity, the magnetic switches can be outside the cavity. If a plunger core attached to the sinking spindle, so may be outside the wall of the cavity, a coil that measures the depth of immersion of the plunger core.

In order to ensure the permanent tightness and at the same time to be able to interrogate the immersion depths, so the cavity in which the lowering element is arranged should be surrounded by a closed wall, but the position of the lowering element must remain measurable. For example, with a countersunk spindle as a countersinking element, several magnets can be placed in the spindle neck tube whose magnetic fields actuate corresponding magnetic switches (eg reed contacts or Hall sensors). The state patterns supplied by the magnetic switches (each 0 or 1) describe the respective immersion depths of the sealing spindles. The distance between the magnets on the Spindelhalsrohr may be different from the distance between the movable magnetic switches, so that a resolution of the immersion depth can be achieved by the different combinations of actuated magnetic switch, which is much more accurate than the distance between the individual magnets.

By choosing several magnets and magnetic switches and staggered distances, an arbitrarily high accuracy can be achieved in determining the concentration.

Of course, other measuring devices for detecting the movement of the sinker, such as a coil and spool core are suitable. By dipping the coil core, the inductive resistance of the coil changes. The resistance value is clearly assigned to a specific position of the sinker.

An incremental measuring scale and an optical detecting device for reading the measuring scale can also be used. In this case, for example, scales with alternating transparent and opaque fields are moved past a light barrier. However, such measuring devices can only measure relative displacements. At the beginning of an operating phase, a zero point determination must be made. Alternatively, assistive measurement devices can provide a coarse position value and provide the incremental measurement scale with the high-resolution measurement value.

The second element for determining the position of the lowering element may be attached to a float which floats on the surface of the measured liquid. In this case, the position of the lowering element relative to the surface of the liquid is measured directly, so that the measured value can be converted directly into a density value.

Alternatively, as in the above drawing, the second element may be attached to a wall of the cavity. This construction is very easy to perform. In order to obtain a relative value of the position of the lowering element in comparison to the liquid level, then the absorption chiller may further comprise a device for determining the filling level of the liquid in the cavity. This can, for. B. has an overflow, which causes a drainage of the solvent in the cavity upon reaching a certain level. This ensures that the filling level is always the same.

However, the device for determining the filling level of the liquid can also have a float in the cavity or a cavity communicating with the space, which is coupled to a height measuring arrangement. The height measuring arrangement for the float can be constructed and operate according to one of the above principles as the sensor arrangement for detecting the movement of the lowering element. Also, the space surrounding the float may be sealed from the environment to hold the vacuum.

The space surrounding the float may be connected to the cavity via a channel below the surface of the liquid. As in a U-tube are then in both rooms at all times the same liquid levels, provided that the pressure above the liquid column just in case the same in both rooms.

The absorption refrigerating machine may include a control device and a device for selectively dispensing components of the liquid, wherein the control device dispenses a certain amount of one of the components into the liquid on the basis of a measuring signal of the device for determining the concentration of the liquid. By such a device too high a concentration can be avoided by adding water. Too low a concentration can be increased again by the addition of a substance dissolved in water, for example lithium bromide, an acid or an alkali.

• • eine Garvorrichtung, welche einen Garraum, eine Heizvorrichtung und einen Abgaskanal für Abgase aus der Heizvorrichtung und/oder aus dem Garraum aufweist,
• • eine Kühlvorrichtung, welche eine Absorptionskältemaschine aufweist, die mit einem wässrigen Kältemittel Temperaturen unter dem Gefrierpunkt von Wasser erzeugt,
• • einen Eisspeicher, in dem die Kälteenergie gespeichert werden kann.

The absorption refrigerating machine according to the invention can be used in particular in a system for the production of food, which comprises the following:

• A cooking device which has a cooking chamber, a heating device and an exhaust gas duct for exhaust gases from the heating device and / or from the cooking chamber,
• A cooling device having an absorption chiller that produces temperatures below freezing point of water with an aqueous refrigerant,
• • an ice storage, where the cold energy can be stored.

Such a system has the considerable advantage that the refrigerant is neither toxic nor flammable by using an aqueous refrigerant over with ammonia absorption refrigeration machine. The period in which the need for refrigeration is high often differs from the period of greatest waste heat from the oven or similar cooking device. In other words, at other times, low temperatures are needed in an air-conditioned room, as high temperatures occur in the exhaust gas. Through the ice storage, in which water or other freezing medium is present, the generated cold can be stored by ice formation until it is needed. The ice storage stores the low temperature (cold energy) by the melting enthalpy of the frozen medium. During melting, energy is removed from a coolant passed through the ice storage at a low temperature level. With the coolant, a proofing room for dough pieces or another cold room can be cooled to the required temperature level.

Such a system preferably comprises an absorption chiller with a concentration measuring device as described above. It may further comprise at least one conditioned space, in particular a fermentation room, refrigerator or freezer, for storing the food, which is cooled by the cooling device and / or the ice storage.

In a method for operating an absorption refrigerator with a refrigerant and a solvent, in one aspect of the invention, the solvent may be maintained at a concentration near the crystallization limit, and during operation, the concentration of the solvent may be determined and maintained at the predetermined concentration level. Highly concentrated solvents and low water vapor pressures allow cooling temperatures well below freezing point of water. The evaporation pressure of the water can be of the order of magnitude of 2 mbar, resulting in an evaporation temperature of about -10 ° C.

According to one aspect of the invention, a method for the production of food in a cooking device is proposed which has a cooking chamber, a heating device and an exhaust gas exhaust gas duct from the heating device and / or from the cooking chamber, and with a cooling device. The cooling device is cooled by means of an absorption chiller with an aqueous refrigerant. The absorption chiller is supplied through an exhaust duct for exhaust gases from the heater and / or from the oven or via an intermediate medium such as hot water thermal energy. The cooking device may in particular be an oven.

Embodiments of the invention will be described below with reference to the accompanying drawings.

1 shows the above-described, schematic representation of the fluid circuit of an absorption refrigeration machine according to the prior art.

2 shows a first embodiment of a device according to the invention for determining fluid concentrations.

3 shows a second embodiment of a device for determining fluid concentrations.

4 shows an inventive system for the production of food.

5 shows one of the 1 Similar representation of a method according to the invention for the operation of an absorption chiller.

The function of a conventional absorption chiller according to 1 is described in detail above. In such an absorption refrigeration machine with the refrigerant water, this refrigerant flows out of the condenser 5 , which is at a high pressure level, via an expansion throttle 6 to an evaporator 1 , Here the water evaporates in a vacuum. The water vapor flows over to an absorber 2 and is absorbed here by a solvent. The solvent is usually an aqueous lithium bromide solution. The solvent pump 3 circulates the solvent and drives it through the regenerative heat exchanger 8th Often made from a plate heat exchanger to the desorber 4 where the water vapor is driven off by heat and the condenser 5 is forwarded.

For such an absorption chiller to operate at optimum efficiency, the solvent should be present in high concentration. Nevertheless, the concentration must not exceed the crystallization limit. For this reason, it makes sense to connect the line through which the low-water solvent from the desorber 4 to the absorber 2 is directed, a device according to the invention for determining the solvent concentration may be provided. A first embodiment of such a device is in 2 shown. It includes a cavity 9 in which the liquid 10 whose concentration is to be determined. The example described is the liquid 10 around the solvent. Upwards, the cavity extends 9 in two closed pick-up tubes 11 . 12 in which the measurement mimic for determining the solvent concentration is arranged. Below the first pick-up tube 11 there is a lowering spindle 13 whose specific gravity is substantially the specific gravity of the solvent 10 equivalent. Depending on the concentration of the solvent 10 therefore protrudes the spindle neck 14 more or less far in the receiving tube 11 into it.

In the spindle neck 14 are several permanent magnets 15 arranged with a ledge 16 interact, in which a plurality of magnetic switches (reed contacts) are arranged. Depending on the immersion depth of the countersink spindle 13 actuate the permanent magnets 15 in the spindle neck 14 a specific combination of magnetic switches on the switch panel 16 , An electronic evaluation system can use the switching states of the magnetic switch, the immersion depth of the Senkspindel 13 determine.

At the in 2 As shown embodiment, this immersion depth is relative to the receiving tube 11 determined. To determine the density and thus the concentration of the solvent 10 but is the immersion depth of the lowering spindle 13 to determine relative to the liquid level. This is why in 2 another measuring mimic shown. It is essentially in the pickup tube 12 added. Here is a dipstick 17 with permanent magnets 15 arranged. These also work with a button bar 16 outside the pickup tube 12 together, in which there are several magnetic switches. The dipstick 17 is on a float 18 arranged, which floats on the liquid surface. Unlike the spindle 13 instructs the swimmer 18 a much lower specific gravity than the liquid 10 , It thus floats independently of the variations in the density of the liquid 10 essentially with a constant, very low immersion depth on the surface of the liquid 10 , The switches of the button bar 16 on the second recording tube 12 thus give the height of the liquid level again. The immersion depth of the countersink spindle can be determined from both measured values 13 into the liquid 10 determine which is proportional to the density of the liquid 10 is. The density in turn depends solely on the concentration of the liquid 10 off, so with the in 2 shown arrangement automatically and continuously the concentration of the liquid 10 can measure.

It should be noted that the representation in 2 is only schematic and does not limit the scope of the invention. In particular, in practice, the cavity for receiving the lowering spindle 13 and the swimmer 18 not designed as an arbitrarily large tub. swimmer 18 and lowering spindle 13 can be arranged in narrow receiving spaces, which communicate with each other via channels that open below the liquid level. It must be ensured that the same pressure prevails above the liquid level. This can be achieved for example by a relief hole, which is the upper end of the receiving tube 11 with the upper end of the pickup tube 12 combines.

The 3 shows an alternative embodiment of a density measuring device. Here is in a pickup tube 11 ' a coil 19 by a swimmer 18 ' will be carried. In the interior of the coil 19 protrudes a metallic and preferably ferromagnetic spindle neck 14 ' , The inductive resistance of the coil 19 is a measure of the immersion depth of the spindle neck 14 ' in the coil 19 , The spindle neck 14 ' is in turn part of the lowering spindle 13 ' , which depends on the density of the liquid 10 more or less deep in this fluid 10 dips. Via flexible connection wires 20 . 21 the coil 19 the inductive resistance can be measured. This measured value is representative of the immersion depth of the countersink spindle 13 ' into the liquid 10 and consequently for the density and thus the concentration of the liquid 10 ,

As mentioned above, a non-contact signal transmission through the closed wall of the cavity may be desired. In this case, the coil may be located outside of the pick-up tube and the core, which dips into the coil at different depths, may be within the closed pick-up tube. In this case, however, the relative position of the core is again measured to the receiving tube, so that the core should be arranged on a spindle and the liquid level should be kept constant by the cavity, for example, has a drain and the cavity is permanently supplied with liquid via an inlet.

Is with the measuring arrangement of the 2 or the 3 too high a concentration of the liquid 10 measured near the Crystallization limit, so the concentration can be influenced by changing the operating parameters. For example, the heat supply can be interrupted to evaporate water, so that the concentration does not increase further. Alternatively, the liquid can be diluted by adding water. If the concentration becomes too low, a further decrease of the concentration can be avoided by changing the operating parameters (increasing the heat input to accelerate the evaporation). Alternatively, salts or other components dissolved in the water can be added to increase the concentration. For this purpose, an automatic metering device would be provided, which is controlled by an automatic control device on the basis of the measurement signals. In an embodiment described below with two coupled absorption cycles, certain amounts of highly concentrated or low-concentration liquid can be transferred from one absorption cycle to the other in order to keep the concentration in the predetermined range.

The 4 shows a system for the production of food, especially baked goods, which is ideal for the use of absorption chillers. Shown are two ovens 22 , The baking steam and the exhaust gas from the burners of the ovens 22 is in a common exhaust duct 23 directed. This exhaust duct 23 leads to an absorption chiller 24 , which is operated with the refrigerant water. Alternatively, exhaust gas and baking steam can of course also be routed via separate channels to the absorption chiller. Preferably, the absorption chiller operates 24 according to the working method, which is described below in connection with the 5 is described.

A coolant contained in the evaporator of the absorption chiller 24 is cooled to -10 ° C, flows to an ice storage 25 ,

The ice storage 25 contains receptacles for water or a similar, ice-forming liquid. When baking a large number of baked goods creates a great heat, which in the absorption chiller 24 leads to the generation of a large amount of cold energy. This occurs in the form of a large amount of coolant at low temperature in the ice storage and here causes the formation of ice. At a later date, for example, if before the next baking process dough pieces for baked goods have to be deep-frozen for a long time or fermented at low temperature, the cooling energy can be retrieved. An air-conditioned room, especially a fermentation chamber 26 is with the ice storage 25 connected. A coolant flowing through the ice storage is cooled and then flows into the fermentation chamber 26 to cool them.

The ice storage 25 allows the time of occurrence of maximum waste heat from the ovens 24 in time from the time of the maximum cooling capacity in the fermentation chamber 26 to separate.

To create cold energy even at times when at the ovens 22 no waste heat is created, the absorption chiller can 24 additionally be provided with a burner or connected to another heating system.

The 5 shows a novel absorption refrigeration process, with which reliable temperatures can be generated by the refrigerant water far below freezing point. The temperatures of the refrigerant can be -10 ° C.

In order to realize such low cooling temperatures with the refrigerant water, in addition to the absorption cycle, which in the 5 in the right half of the diagram, a refrigerant absorption loop is introduced, which is shown in the left half of the diagram.

In the evaporator 1 is first produced in a conventional manner in a vacuum water vapor, which causes by the evaporation enthalpy the low temperature of the refrigerant. The steam is generated in a vacuum at about 2 mbar pressure. At this pressure, water evaporates at temperatures below -10 ° C. In the evaporator, the useful cooling, which can be transferred to an external coolant. The water vapor is transferred to an absorber 2 where it is taken up in the solvent. This creates a waste heat, the z. B. is removed by cooling water. This cooling water can in turn be used to supply heat at a lower temperature level. From the absorber 2 the solvent gets over the solvent points 3 to the desorber 4 pumped. It goes through a regenerative heat exchanger 8th (Plate heat exchanger) in which it is heated by the refluxing, low-water solvent. In the desorber 4 the solvent is heated, the water being expelled from the solvent by supplying heat. The low-water solvent then flows through the expansion throttle 7 back to the absorber 2 , The solvent circuit essentially corresponds to the solvent circuit 1 ,

Unlike in the known absorption chiller according to 1 is on the side of the evaporator 1 but no pure water available. The water vapor from the desorber 4 flows into a resorber 27 in which it is absorbed by a low-water solution. Preferably, the solution in the left circle with resorber 27 and evaporator 1 the same ingredients as the solution in the right circle with absorber 2 and desorber 4 , In addition to water, these may be, for example, salts such as lithium bromide. Preferably, an acid and / or alkali, z. For example, sulfuric acid and sodium hydroxide solution, added to the water. These admixtures lower the freezing point of the water considerably and far below -10 ° C. They thus allow a refrigerant temperature in the evaporator 1 which is well below freezing point of water. After the recording of the desorber 4 originating water in the resorber 27 while giving off heat energy, the water-rich solvent flows from the resorber 27 through a regenerative heat exchanger 28 and the relaxation throttle 7 to the evaporator 1 ,

Unlike the absorption chiller according to the prior art ( 1 ), the fluid in the variant according to 5 not completely evaporated in the evaporator. Only part of the water in the fluid evaporates. The highly concentrated fluid is then removed from the evaporator by means of a refrigerant pump 29 through the heat exchanger 28 back to the resorber 27 pumped. In the heat exchanger 28 the refrigerant is heated. In the resorber 27 she takes the steam from the desorber again 4 and flows as a water-rich solution back to the evaporator 1 ,

The introduction of this Resorptionskreises means that not pure water, but an aqueous solution with well below -10 ° C is present in the evaporator. It also allows concentration shifts between the solution in the evaporator / resorber circuit and in the absorber / desorber circuit, as described above.

The 5 also shows possible locations for the arrangement of concentration measuring devices 30 as they are in the 2 and 3 are shown. In the refrigerant circuit between the evaporator 1 and the resorber 27 can the concentration measuring device 30 in the pipe for out of the evaporator 1 pumped highly concentrated refrigerant can be arranged. The concentration measuring device 30 is in 5 immediately behind the vacuum evaporator 1 arranged. It can also be in the line for the highly concentrated refrigerant immediately before the resorber 27 be arranged, in which there is a higher pressure. In this case, the requirements for the sealing of the concentration measuring device 30 lower.

In the solvent circuit between the absorber 2 and desorber 4 is the concentration measuring device 30 placed in the pipe by the desorber 4 after expelling water vapor from the solvent back to the absorber 2 leads. At this point, the solvent has the highest concentration.

Based on the measurements of the concentration measuring devices 30 On the one hand, the concentration in the refrigerant circuit and in the solvent circuit can be controlled individually by suitable control means (not shown). On the other hand, concentration shifts can be realized, which can be advantageous depending on the operating state. At the same time, therefore, the concentration in the refrigerant circuit can be increased and lowered in the solvent circuit or vice versa.

LIST OF REFERENCE NUMBERS

1

Evaporator

2

absorber

3

Solvent pump

4

desorber

5

capacitor

6

relaxation throttle

7

relaxation throttle

8th

Regenerative heat exchanger

9

cavity

10

Liquid, solvent

11

receiving tube

12

receiving tube

13, 13 '

hydrometer

14, 14 '

spindle neck

15

permanent magnet

16

strip

17

dipstick

18, 18 '

swimmer

19

Kitchen sink

20

Lead wire

21

Lead wire

22

oven

23

exhaust duct

24

Absorption chiller

25

Ice storage

26

fermentation chamber

27

resorber

28

regenerative heat exchanger

29

Refrigerant pump

30

Concentration measuring device

Claims (25)

Method for producing cold by means of an absorption chiller with - an evaporator ( 1 ) for a water-containing refrigerant, - an absorber ( 2 ) in which the vaporized refrigerant is absorbed in a solvent, - a desorber ( 4 ), in which the absorbed refrigerant is expelled from the solvent under heat, characterized in that the refrigerant vapor expelled from the solvent is a resorber ( 27 ), wherein in the resorber ( 27 ) is added a solution of refrigerant and antifreeze, in which the refrigerant vapor is absorbed, and wherein the solution of refrigerant and antifreeze in the evaporator ( 1 ) is passed to evaporate the refrigerant from the solution. A method according to claim 1, characterized in that the refrigerant from the evaporator ( 1 ) with low temperature to the resorber ( 27 ) flows through a first conduit, and that the higher temperature refrigerant from the resorber ( 27 ) to the evaporator ( 1 ) flows through a second line, wherein both refrigerant flows a heat exchanger ( 28 ), in which the from the evaporator ( 1 ) on the way to the resorber ( 27 ) and that of the resorber ( 27 ) refrigerant flow on the way to the evaporator ( 1 ) is cooled. A method according to claim 1 or 2, characterized in that the solvent from the absorber ( 2 ) at low temperature through a third line to the desorber ( 4 ) and that the solvent from the desorber ( 4 ) to the absorber ( 2 ) flows through a fourth line, wherein both solvent streams a heat exchanger ( 8th ), in which the of the absorber ( 2 ) solvent stream on the way to the desorber ( 4 ) and that of the desorber ( 4 ) solvent stream on the way to the absorber ( 2 ) is cooled. A method according to any one of claims 1 to 3, characterized in that the solvent is kept at a concentration near the crystallization limit and determined during operation, the concentration of the solvent and maintained at the predetermined concentration value. Method according to one of claims 1 to 4, characterized in that food in a cooking device ( 22 ), which a cooking chamber, a heater and an exhaust duct ( 23 ) for exhaust gases from the heating device and / or from the cooking chamber, and are produced in a cooling device, wherein the cooling device by means of the absorption chiller ( 24 ) is cooled. Method according to claim 5, characterized in that the absorption chiller ( 24 ) through an exhaust duct ( 23 ) is supplied for exhaust gases from the heater and / or from the oven thermal energy. Absorption chiller with - an evaporator ( 1 ) for a water-containing refrigerant, - an absorber ( 2 ) in which the vaporized refrigerant is absorbed in a solvent, - a desorber ( 4 ), in which the absorbed refrigerant is expelled from the solvent with the supply of heat, characterized in that it comprises a resorber ( 27 ), to which the refrigerant vapor expelled from the solvent is supplied, wherein in the resorber ( 27 ) a solution of refrigerant and antifreeze is received, in which the refrigerant vapor is absorbed, and wherein in the evaporator ( 1 ) the solution of refrigerant and antifreeze is contained, from which the refrigerant is evaporated. An absorption refrigerating machine according to claim 7, characterized by a first line through which the low-temperature refrigerant from the evaporator ( 1 ) to the resorber ( 27 ), and a second line through which the higher temperature refrigerant from the resorber ( 27 ) to the evaporator ( 1 ) flows, with both lines to a heat exchanger ( 28 ) are connected in which the of the evaporator ( 1 ) on the way to the resorber ( 27 ) and that of the resorber ( 27 ) refrigerant flow on the way to the evaporator ( 1 ) is cooled. Absorption refrigerating machine according to claim 7 or 8, characterized by a third conduit in which the low temperature solvent is removed from the absorber ( 2 ) to the desorber ( 4 ), and a fourth line in which the solvent from the desorber ( 4 ) to the absorber ( 2 ) flows, these two lines through a heat exchanger ( 8th ) in which the of the absorber ( 2 ) solvent stream on the way to the desorber ( 4 ) and that of the desorber ( 4 ) solvent stream on the way to the absorber ( 2 ) is cooled. Absorption refrigerating machine according to one of claims 7 to 9 with at least one liquid and with a device for determining the concentration of the liquid, characterized in that this device comprises: 9 ), in which liquid ( 10 ) and one in the liquid ( 10 ) submerged sinker ( 13 . 13 ' ), a sensor arrangement ( 15 . 16 ; 14 ' . 19 ) for detecting the movement of the lowering element ( 13 . 13 ' ). Absorption refrigerating machine according to claim 10, characterized in that the sensor arrangement ( 15 . 16 ; 14 ' . 19 ) has at least one of the below enumerated pairs consisting of two interacting elements, wherein the first element of the pair on the lowering element ( 13 . 13 ' ): • magnet ( 15 ) and magnetic switch; • Kitchen sink ( 19 ) and spool core ( 14 ' ); • incremental measuring scale and an optical detection device for reading the measuring scale. Absorption cold machine according to claim 11 or 12, characterized in that the sensor arrangement ( 15 . 16 ; 14 ' . 19 ) that the movement of the lowering element ( 13 . 13 ' ) transmits signal through a closed wall. Absorption cold machine according to claim 11 or 12, characterized in that the second element ( 19 ) of the couple on a float ( 18 ' ) attached to the surface of the liquid ( 10 ) is swimming. Absorption cold machine according to claim 10 or 11, characterized in that the second element ( 16 ) of the pair on a wall of the cavity ( 9 ) is attached. Absorption chiller according to claim 14, characterized in that it further comprises a device for determining the filling level of the liquid in the cavity ( 9 ) having. Absorption chiller according to claim 15, characterized in that the device for determining the filling level of the liquid has an overflow, which is a drainage of the liquid in the cavity ( 9 ) when reaching a certain level causes. Absorption chiller according to claim 16, characterized in that the device for determining the liquid level of a liquid ( 18 ) in the cavity ( 9 ) or one with the cavity ( 9 ) communicating space which is coupled to a height measuring arrangement. Absorption chiller according to claim 17, characterized in that the height measuring arrangement comprises at least one of the following enumerated pairs of mutually cooperating elements, wherein an element on the float ( 18 ) and the other element on the float ( 18 ) surrounding wall are: • magnet ( 15 ) and magnetic switch; • Kitchen sink ( 19 ) and spool core ( 14 ' ); • incremental measuring scale and an optical detection device for reading the measuring scale. Absorption chiller according to claim 17 or 18, characterized in that the height measuring arrangement that the movement of the float ( 18 ) transmits signal through a closed wall. Absorption chiller according to claim 17 to 19, characterized in that the float ( 18 ) surrounding space is sealed from the environment. Absorption chiller according to one of claims 17 to 20, characterized in that the float ( 18 ) surrounding space with the cavity ( 9 ) is connected via a channel below the surface of the liquid. Absorption refrigerating machine according to one of the preceding claims 7 to 21, characterized in that it comprises a control device and a device for the selective dispensing of components of the liquid ( 10 ), the control device being based on a measurement signal of the device for determining the concentration of the liquid ( 10 ) a certain amount of one of the components in the liquid ( 10 ). System for the production of food with a cooking device ( 22 ), which a cooking chamber, a heater and an exhaust duct ( 23 ) for exhaust gases from the heating device and / or from the cooking chamber, and with a cooling device having an absorption chiller ( 24 ) according to one of the preceding claims 7 to 21. System according to claim 23, characterized in that the absorption chiller ( 24 ) with an aqueous refrigerant produces temperatures below the freezing point of water, and that there is an ice storage ( 25 ), in which the low temperatures can be stored. A system according to claim 23 or 24, characterized in that it further comprises at least one conditioned space for storing the food associated with the cooling device and / or the ice storage ( 25 ) is cooled.

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