DE102016112497A1 - System and method for determining molar proportions and mass fractions and the temperature and the thermal state point of a fluid - Google Patents

Abstract

The invention relates to a system (1) for determining molar proportions and mass fractions as well as the temperature and thus the thermal state point of a fluid (3). The system (1) has a sample space with at least one optical window (12), which is acted upon by the fluid (3), at least one radiation source (5), which emits a beam (6), at least one detector (7), which radiation intensities as an irradiation spectrum and converting it into electrical signals, and an evaluation unit (14) configured to receive and analyze the signals generated by the detector (7). In this case, the radiation source (5) and the detector (7) are arranged relative to one another and aligned with the at least one optical window (12) of the sample space such that the beam (6) emitted by the radiation source (5) enters the sample space and out of the Sample chamber exit and impinges when exiting the sample chamber on the detector (7). The invention also relates to a method for determining molar proportions and mass fractions as well as the temperature of a fluid (3) with an aforementioned system (1).

Description

The invention relates to a system and a method for determining molar proportions and mass fractions as well as the temperature and thus the thermal state point of a fluid. The system comprises a sample space through which the fluid flows in a flow direction, at least one radiation source for emitting a jet and at least one detector for recording radiation intensities and their conversion into electrical signals, and an evaluation unit for analyzing the electrical signals.

Refrigerant circuits known from the prior art, for example of air conditioning systems, heat pump systems or refrigeration systems, have a heat exchanger operated as an evaporator for transferring heat to the refrigerant. The refrigerant introduced into the evaporator as a two-phase mixture of vapor and liquid is vaporized when the heat is absorbed and leaves the evaporator essentially in gaseous form. The heat exchanger operated as an evaporator is followed in the flow direction of the refrigerant within the refrigerant circuit, a compressor downstream, which sucks the gaseous refrigerant. Depending on the regulation of the overheating of the refrigerant leaving the evaporator, the refrigerant can emerge from the evaporator as a two-phase mixture of vapor and liquid or in a pure gas phase. The proportions of liquid in the gaseous phase of the refrigerant are mostly in the form of drops. The refrigerant circuit may further include a collector for the refrigerant between the evaporator and the compressor. The collector is provided, inter alia, to deposit the liquid portion of the refrigerant, for example, to protect the downstream of the collector in the flow direction of the compressor from liquid hammer.

Refrigerant compressors are designed to suck in a small amount of liquid with the gaseous phase of the refrigerant without being damaged. However, the proportion of liquid should not exceed a certain maximum liquid content x ' _max in the suction gas. When the maximum liquid content x ' _max is exceeded, the above-mentioned liquid bumps or droplet erosion occur within the compressor. If the refrigerant as it flows into the compressor has a liquid content x 'which is less than the maximum liquid content x' _max (x '<x' _max ), that is, the proportion of liquid is low, the liquid is due to the compression of the refrigerant evaporates and the compressor is not damaged. When the limit value of the liquid content x '>x' _max is exceeded, only a part of the liquid is evaporated during the compression of the refrigerant, so that the remaining liquid causes erosion damage. At present, no reliable and cost-effective way of measuring the liquid content present in the operation and for determining the thermal state point of a multiphase mixture is known.

Furthermore, the compressors arranged in refrigerant circuits are usually oil-lubricated. The oil which performs multiple functions within the refrigeration cycle, on the one hand, serves to lubricate moving components within the compressor, thereby reducing the friction between the components. This reduces, inter alia, the wear of the compressor. On the other hand, by means of the oil, the sealing of the compressor from the environment as well as the internal sealing between the high pressure area and the low pressure area of the refrigerant within the compressor are improved. Another function of the oil within a refrigerant circuit is to absorb and dissipate the heat generated, for example, due to the friction between the moving components of the compressor within the compressor.

Although the oil is essentially only needed within the compressor, the compressed gas also promotes a certain proportion of the refrigerating machine oil into the refrigerant circuit, so that the oil also circulates within the refrigerant circuit.

The oil of the compressor, which circulates together with the refrigerant through the refrigerant circuit, has various effects. It changes the physical and thermodynamic properties of the refrigerant-oil mixture. The oil, for example, reduces the effectiveness of the heat exchanger of the refrigerant circuit. If the heat transfer surfaces are covered in the interior of the heat exchanger with an oil film, which acts as an additional insulating layer, the heat transfer and thus the heat transfer are adversely affected. The proportion of oil pumped into the refrigerant circuit has, with a few exceptions, thus unfavorable effects on the refrigerant circuit. The performance and efficiency of the system will be lower. The knowledge of the oil content of circulating in the refrigerant circuit refrigerant is particularly desirable in the development and tuning of refrigeration systems, for example in air conditioning systems of motor vehicles. Also a continuous one Monitoring the oil content, the temperature and the composition of all phases and their proportions - expressed by the thermal state point - during operation is advantageous. In addition, it would be desirable to be able to determine the oil content in multiphase refrigerant mixtures, for example with the phases of vapor and liquid, liquid and liquid or a combination thereof, to determine the oil content between all components of the refrigerant circuit and in the presence of a miscibility gap and oil displacements in to be able to recognize one of the components of the refrigerant circuit.

From the state of the art is currently not always reliable economic method known to measure the mole fraction, in particular the steam mass fraction and the oil mass fraction, or the temperature and the thermal state point of a refrigerant-oil mixture online and to use the measured values as a controlled variable. For the determination of the oil mass fraction in a refrigerant-oil mixture, sensors based on sound velocity measurements or density measurements are conventionally used. However, the measurements fail on the basis of the speed of sound when miscibility gaps or gas bubbles occur within the flow. Measurements of composition of the fluid based on densities fail in areas of density inversion, that is, in areas where the density of the oil and the density of the refrigerant are equal. With these methods or measuring effects, an integrated temperature measurement is not possible and must be carried out additionally, in particular if the thermal state point is to be determined.

The object of the invention is to provide a system and a method for determining the mass fractions of the components and the phases, their temperature and thus the thermal state point of a fluid, in particular a refrigerant, a refrigerant mixture or a refrigerant-oil mixture, each within a refrigerant circuit having at least one expansion element, a heat exchanger operated as an evaporator, a compressor and a heat exchanger operated as a condenser. The mass fractions of the components and the phases, their temperature and thus the thermal state point of the fluid should be continuously determinable, wherein the flow of the fluid should not be affected by the measurement. The mass fractions of the components and their phases, their temperature and thus the thermal state point of the circulating fluid should also be specifically determined between a heat exchanger operated as an evaporator and a compressor to use them as control variables for the relaxation of the fluid when flowing through the expansion device , Furthermore, the mass fraction of the oil within the refrigerant-oil mixture, preferably in the flow direction of the refrigerant-oil mixture should be determined by a heat exchanger operated as a condenser. The system should also be structurally simple to implement, robust against shocks and easy to use, to ensure the most space-saving installation and to minimize the costs of manufacturing, maintenance and operation.

The object is achieved by the subject matters with the features of the independent claims. Further developments are specified in the dependent claims.

The object is achieved by an inventive system for determining molar proportions and mass fractions and the temperature and thus the thermal state point of a fluid, in particular a refrigerant, a refrigerant mixture or a refrigerant-oil mixture. The refrigerant can be present in each case single-phase as a vapor or liquid or as a two-phase mixture of vapor and liquid. According to the concept of the invention, the system has a sample space with at least one optical window, at least one radiation source which emits a beam, at least one detector which receives radiation intensities as a radiation spectrum and converts them into electrical signals, and an evaluation unit. The sample chamber is charged with the fluid. The evaluation unit is configured to receive and analyze the signals generated by the detector. The radiation source and the detector are arranged relative to one another and aligned with the at least one optical window of the sample space such that the beam emitted by the radiation source enters the sample space and exits from the sample space and impinges upon the detector upon exiting the sample space.

The components of the system are advantageously formed at least partially or in total integrated in one unit. The integrally formed within the common unit components are arranged contiguous. The fluid can flow through the sample space at a flow rate. Alternatively, the fluid within the sample space may have zero flow velocity.

According to a first alternative embodiment of the invention, the system is formed with an optical window and a reflection device, wherein the beam emitted by the radiation source beam enters the sample space through the optical window, is reflected at the reflection device and exits the sample space through the optical window. According to a second alternative embodiment of the invention, the system is formed with at least two optical windows, the beam emitted by the radiation source entering the sample space through a first optical window and exiting the sample space through a second optical window. According to a third alternative embodiment of the invention, sensors and detectors are arranged directly in the fluid or disposed within the fluid, so that the system has no optical window.

The at least one optical window of the sample space is preferably formed protected against fog, in particular heated.

According to an advantageous embodiment of the invention, the radiation source and the detector are arranged in such a way and aligned with the sample space that the beam penetrates the sample space and the fluid in a direction which is aligned perpendicular to a flow direction of the fluid.

A development of the invention is that the sample space is formed within a conduit. In this case, the line has the shape of a circular cylinder and the cross section has a diameter, in particular an inner diameter. The radiation source and the detector are advantageously arranged in such a way to each other and aligned to the sample space that the beam penetrates the circular cylindrical conduit along the diameter. According to an alternative embodiment, the cross section has a polygonal, in particular a rectangular shape.

The line is preferably designed as a universally applicable element with standardized connection points, in particular as a section of a tube.

According to an advantageous embodiment of the invention, the system is formed with a bypass with a sample chamber same space, a beam splitter and an additional detector. The sample chamber-like space in this case has identical geometric dimensions, in particular an identical optical length, to the sample space. The sample chamber-like space does not contain a substance which absorbs and emits infrared-active radiation, which interacts with one of the components of the fluid to be investigated and is used to determine the molar proportions and mass fractions and the temperature. The sample chamber-like space is consequently exposed to an infrared-inactive fluid in the spectral range to be examined. The beam splitter is preferably formed within the radiation source to divide the beam emitted by the radiation source and to pass a first portion of the beam through the bypass and thus the sample space equivalent space and a second portion of the beam through the sample space.

According to a development of the invention, the at least one radiation source is designed as a light source which emits a light beam having at least one predetermined wavelength. The at least one detector is designed to receive transmission light intensities as a transmission light spectrum and to convert the transmission light intensities into electrical signals.

According to a first alternative embodiment of the invention, a plurality of monochromatic light sources is formed. Among a multitude are at least two light sources to understand. According to a second alternative embodiment of the invention, at least one polychromatic light source is emitted, which emits light having different predetermined wavelengths.

The at least one detector is advantageously designed as a photodetector. In the embodiment of the invention with a detector, the detector is designed to detect lambda selectively. In the embodiment of the invention with more than one detector, the detectors can also be designed to detect only monochromatically.

• – Bestimmen von Referenzstrahlungsintensitäten I₀(ν_i),
• – Aufnehmen eines Strahlungsspektrums durch den mindestens einen Detektor, wobei eine Anzahl i von spezifischen Wellenlängen Strahlungsintensitäten I_Probe(ν_i) zugeordnet werden, und Umwandeln der aufgenommenen Strahlungsintensitäten in elektrische Signale,
• – Senden der elektrischen Signale an eine Auswerteeinheit und Analysieren der Signale innerhalb der Auswerteeinheit, Bestimmen von Strahlungsintensitäten I_Probe(ν_i),
• – Bestimmen einer Absorbanzverteilung A(λ_i) aus den Strahlungsintensitäten I_Probe(ν_i) und den dazugehörigen Referenzstrahlungsintensitäten I₀(ν_i) für i spezifische Wellenlängen,
• – Bestimmen mindestens einer Nullabsorbanz A_Null(λ_Null), wobei Photonen der Wellenlänge λ_Null mit keiner der zu untersuchenden Komponenten des Fluids absorbiert,
• – Bestimmen von Stoffmengenanteilen und/oder Massenanteilen der Komponenten sowie deren Phasen des Fluids, basierend auf der Absorbanzverteilung A(λ_i) und dem Verhältnis charakteristischer Absolutwerte der Absorbanzen A,
• – Bestimmen der Temperatur des Fluids, basierend auf der Absorbanzverteilung A(λ_i) und dem Verhältnis charakteristischer Absolutwerte der Absorbanzen A, sowie
• – Bestimmen des thermischen Zustandspunktes mit einer in der Auswerteeinheit gespeicherten Zustandsgleichung.

The object is also achieved by an inventive method for determining molar proportions and mass fractions and the temperature and thus the thermal state point of a fluid with an aforementioned system. In this case, at least one beam emitted by at least one radiation source into a sample space which can be acted upon by the fluid strikes predetermined wavelengths after the sample space has been irradiated on at least one detector. The method comprises the following steps:

• Determining reference radiation intensities I ₀ (ν _i ),
• Recording a radiation spectrum through the at least one detector, a number i of specific wavelengths being assigned to radiation intensities I _sample (v _i ), and converting the recorded radiation intensities into electrical signals,
• - transmitting the electrical signals to an evaluation unit, and analyzing the signals within the evaluation unit, determining radiation intensities I _sample (ν _i),
• Determining an absorbance distribution A (λ _i ) from the radiation intensities I _sample (v _i ) and the associated reference radiation intensities I ₀ (v _i ) for i specific wavelengths,
• Determining at least one _zero absorbance A _zero (λ _zero ), with photons of wavelength λ _zero absorbing none of the components of the fluid to be investigated,
• Determining molar proportions and / or mass fractions of the components and their phases of the fluid, based on the absorbance distribution A (λ _i ) and the ratio of characteristic absolute values of the absorbances A,
• Determining the temperature of the fluid, based on the absorbance distribution A (λ _i ) and the ratio of characteristic absolute values of the absorbances A, as well as
• Determining the thermal state point with a state equation stored in the evaluation unit.

The _zero absorbance A _zero (λ _zero ) can thus be advantageously used as a reference point for a baseline A = 0 in order to take into account possible scattering effects. The other determined absorbance distributions A (λ _i ) can be corrected with the _zero absorbance A _zero (λ _zero ) as a so-called offset shift: ΔA _i (λ _i ) = A _i (λ _i ) -A _zero .

If, according to a development of the invention, the at least one radiation source is designed as a light source which emits a light beam and the at least one detector is designed to record transmission light intensities, the method advantageously comprises the acquisition of a transmission light spectrum, specific wavelengths transmission light intensities I _sample (ν _i ) be assigned.

According to a first alternative embodiment of the invention, the reference radiation intensities I ₀ (ν _i ) are determined by a single measurement or a single measurement series of the beam through the unbuffered sample space and then stored in the evaluation unit. According to a second alternative embodiment of the invention, the reference radiation intensities I ₀ (ν _i ) are determined simultaneously with the radiation intensities I _sample (ν _i ). A beam splitter, which is arranged in the radiation source, impinges on a detector through a beam guided in the same sample space. The sample chamber-like space is formed with identical geometric dimensions, in particular an identical optical length, as the sample space and acted upon by an infrared-active in the spectral range to be examined fluid.

The method according to the invention advantageously serves to determine an integral mean of the concentrations as molar proportions, the temperature and the thermal state point along the jet during penetration of the fluid flowing within the sample space. The method is preferably based on a so-called "in situ" and online measurement. An "in situ" measurement is to be understood as meaning a measurement in which the fluid to be measured continuously flows through the sample space during the measurement and the fluid or the sample remains unaffected by the measurement; in particular, no partial mass flow of the fluid is withdrawn and withdrawn a separate measuring device analyzed. The measurement is carried out directly on site. An introduction of measuring components in the flow path is not required.

A development of the invention consists in that a baseline is determined for the evaluation of the measured values. In this case, a wavelength is provided for the beam sources, which interacts with none of the components or phases of the fluid.

At least a mole fraction and the temperature of the fluid are advantageously determined from rotational vibration spectra, wherein the evaluation on the shift of the wavelength of the stretching vibration band between two phases and / or on the resolution of the fine structure of two phases and / or vibrations of hydrogen bonds, in particular in the infrared spectrum of liquids, based. As different phases are advantageously at least one gas phase and at least considered a liquid phase. The fine rotational structure is understood to mean a spectral fine structure of rotational vibration bands.

The molar mass fractions or the mass fractions of the phases and / or the substances of the fluid, in particular a steam mass fraction or an oil mass fraction of a refrigerant, a refrigerant mixture or a refrigerant-oil mixture, are preferably according to Lambert-Beer's law and taking into account the material data the mixture determined and optionally deposited as an equation of state in the evaluation unit. The temperature of the fluid is determined at constant optical length advantageous from at least one absorbance of the vapor .DELTA.A _gas and / or the liquid .DELTA.A _liquid according to the Boltzmann distribution. The temperature is determined alternatively or additionally with a separate temperature sensor.

A further preferred embodiment of the invention is that absorption bands are compared with spectral distributions, which are predetermined for known amounts of substance and temperatures and deposited, for example, in a database, to determine the amounts of substances of the components and phases and the temperature.

The measured values to be determined are advantageously recorded online and virtually instantaneously. The measured values are processed without delay for recording, so that the measured values can be used as controlled variables.

According to a development of the invention, the method is used to control a refrigerant circuit which has at least one expansion element, at least one heat exchanger operated as an evaporator and at least one compressor in the flow direction of the fluid. The system is arranged in the flow direction of the fluid after a heat exchanger and in front of a compressor. The values determined with the system are used as a control variable for regulating the refrigerant circuit. The method is also advantageously applicable to branched and multi-stage refrigerant circuits.

The preferably determined by the system mole fractions, mass fractions and the temperature and thus the thermal state point, for example in the form of the specific enthalpy of the fluid are advantageously used as a control variable for controlling an opening degree of the expansion device.

In the two-phase region occurs depending on the flow shape of the fluid, for example, in a ring flow, a slip, so that it is necessary to distinguish between the circulating mass fraction of the flowing fluid and the local mass fraction of the fluid. The slip between the phases leads to a deviation of the circulating mass fraction of the flowing fluid and the local mass fraction, which can be determined by a spatially resolving measuring method. According to an advantageous embodiment of the invention, an inventive system is arranged in the flow direction of the fluid after a heat exchanger operated as a condenser and in front of the expansion element, wherein the circulating mass fractions of the flowing fluid are determined. In addition, the local mass fractions of the fluid between the operated as an evaporator heat exchanger and the compressor are determined.

Systems according to the invention can advantageously also be arranged at several points of a refrigerant circuit in order to simultaneously determine the molar mass fractions and mass fractions as well as the temperatures and the thermal state points of the refrigerant at the different points. The measurements at several points of the refrigerant circuit, for example, state changes in the refrigerant can be determined within the refrigerant circuit.

• – nicht invasive Messung, wobei die Strömung mechanisch und thermodynamisch unbeeinflusst bleibt,
• – die Messwerte werden online und quasi instantan erfasst, wobei die Messwerte ohne zeitliche Verzögerung zur Aufnahme verarbeitet werden, sodass die Messwerte als Regelgrößen nutzbar sind,
• – In-situ-Messung, wobei die Messung bei sich verändernden Zuständen und Zusammensetzungen des Fluids unmittelbar am Ort stattfindet,
• – mit einer integrierten Temperaturmessung kann der thermodynamische Zustandspunkt des strömenden Fluids, insbesondere eines Kältemittels oder eines Kältemittelgemisches jeweils mit oder ohne Ölanteil bestimmt werden, wobei beispielsweise die spezifische Enthalpie des Nassdampfes von besonderem Interesse ist,
• – dem Verfahren liegen eine Vorrichtung und ein System mit einem einfachen Aufbau aus wenigen Einzelkomponenten zu Grunde,
• – das System ist als Messsystem damit kostengünstig und ermöglicht Anwendungen in Massenproduktionen, auch in Anwendung bei kleinen Leistungsklassen, da die Messung weder vom Strömungszustand des Fluids abhängt, noch den Strömungszustand des Fluids beeinflusst,
• – das System ist sehr robust und unanfällig für Fehler,
• – durch eine Erweiterung des direkten Messverfahrens zu einem ortsauflösenden Messverfahren sowie den Vorteil des unmittelbaren Bestimmens der Stoffmengenanteile und Phasen der Komponenten des Fluids, ist das Verfahren speziell in der Grundlagenforschung zur Untersuchung von Kondensationsmechanismen einsetzbar.

The system according to the invention and the method according to the invention also have, in summary, further advantages:

• Non-invasive measurement, the flow remaining mechanically and thermodynamically unaffected,
• The measured values are recorded online and quasi instantaneously, whereby the measured values are processed without delay for recording, so that the measured values can be used as controlled variables,
• In-situ measurement, wherein the measurement takes place at changing locations and compositions of the fluid directly in place,
• With an integrated temperature measurement, the thermodynamic state point of the flowing fluid, in particular of a refrigerant or of a refrigerant mixture can be determined in each case with or without oil content, for example, the specific enthalpy of the wet steam is of particular interest,
• - The method is based on a device and a system with a simple structure of a few individual components,
• The system is therefore cost-effective as a measuring system and enables applications in mass production, even in small power classes, since the measurement neither depends on the flow state of the fluid nor influences the flow state of the fluid,
• - The system is very robust and not susceptible to errors
• - By extending the direct measurement method to a spatially resolving measurement method and the advantage of directly determining the mole fractions and phases of the components of the fluid, the method can be used especially in basic research for the investigation of condensation mechanisms.

Further details, features and advantages of embodiments of the invention will become apparent from the following description of exemplary embodiments with reference to the accompanying drawings. Show it

1 Range of a refrigerant circuit with the system for determining the mole fraction and the mass fractions and the temperature and thus the thermal state point of a pure fluid or a fluid mixture, in particular the proportions of the phases vapor and liquid of a pure refrigerant or a refrigerant mixture or the proportions the phases vapor and liquid of the refrigerant and the proportion of the liquid oil of a refrigerant-oil mixture,

2 : Scheme for the course of determining the mole fractions and the mass fractions and the phases of the components and the temperature of a pure fluid or a fluid mixture,

3a . 3b : Graphs with a plot of the absorbance as a function of the wave number as possibilities of the evaluation of oscillation spectra for the determination of the phase components steam and liquid and the temperature of a refrigerant on the basis of molar mass fractions or mass fractions,

4 : Diagram showing the absorbance as a function of the wave number using the example of a refrigerant and a refrigerating machine oil of a refrigerant-oil mixture for determining the molar fraction of the refrigerating machine oil.

Out 1 is an area of a refrigerant circuit with the system 1 for determining the mole fractions and the mass fractions and the temperature and thus the thermal state point of a fluid 3 out.

Under a fluid 3 is a pure fluid, that is to say to understand a fluid consisting of a component, or a fluid mixture. In particular, the proportions of the phases gas and liquid of a pure refrigerant or of a refrigerant mixture or the proportions of the phases gas and liquid of the refrigerant and the proportion of the liquid oil of a refrigerant-oil mixture are determined as molar mass fractions and mass fractions. The phase of the gas is also referred to below as the vapor phase, gas phase or vapor. As a fluid 3 are understood specifically as refrigerant from one component or refrigerant mixtures of at least two components or refrigerant-oil mixtures of at least one component of refrigerant and oil. fluids 3 as mixtures of more than one component of refrigerant and oil are also referred to as a refrigerant-refrigerant-oil mixture. The oil can also consist of several components.

The fluid 3 preferably flows as a liquid, or optionally also as a supercritical gas, in the flow direction 4 through the refrigerant circuit to the expansion device 8th and is flowing through the expansion organ 8th in a multi-phase region, in particular a two-phase region with a liquid and a gaseous phase, relaxed. Subsequently, the fluid enters 3 in a heat exchanger operated as an evaporator 9 one. Inside the evaporator 9 becomes the liquid phase, in particular of the refrigerant, of the fluid 3 while absorbing heat Q., also referred to as cooling capacity, evaporates. The fluid 3 occurs essentially vaporous from the evaporator 9 off and off the compressor 10 sucked. Since refrigeration oils generally have a much higher boiling temperature than the refrigerants, oil is located after the evaporation of a refrigerant-oil mixture within the fluid 3 in the form of droplets, foam or as a film.

The fluid 3 flows from the evaporator 9 through the pipe 2 to the compressor 10 , The administration 2 of the refrigerant circuit is with the system 1 for determining the mole fractions and the mass fractions as well whose phase components and temperature and thus the thermal state point formed. It is in an evaluation unit 14 a state function for describing the substance data is stored. Depending on the regulation of overheating of the evaporator 9 leaking refrigerant can in the gaseous phase fractions of liquid as drops 3a be included in the refrigerant. A composite as a refrigerant-oil mixture fluid 3 can be next to the drops 3a the refrigerant also oil drops 3b exhibit. The arrangement of the system 1 within the refrigerant circuit in the flow direction of the fluid 3 after the evaporator 9 and in front of the compressor 10 allows the determination of the thermal state point of the fluid 3 as a controlled variable at the inlet to the compressor 10 , which preferably gaseous fluid 3 should suck. Since the mass fraction of liquid x 'must not exceed a maximum liquid content x' _max in the suction gas in order to prevent liquid impacts or drop impact erosion within the compressor 10 To avoid it is with the help of the system 1 and the one with the system 1 certain mass fractions of the fluid 3 For example, the degree of opening of the expansion device 8th regulated. Alternatively, the system can 1 be disposed within the refrigerant circuit at locations where the refrigerant does not flow, that is, the flow velocity is zero. The refrigerant in this case has no flow velocity, in particular in containers, such as a collector, a separator or an accumulator. Determining the _oil mass fraction x _oil within the refrigerant circuit provides information about how much oil is coming out of the compressor 10 is discharged into the refrigerant circuit.

wird ein als Abschnitt der Leitung 2 mit innerhalb der Leitung 2 in Strömungsrichtung 4 strömendem Fluid 3 ausgebildeter Probenraum von einem Strahl 6 einer Strahlungsquelle 5, insbesondere einem Lichtstrahl 6 von einer Lichtquelle 5, mit festgelegten Wellenlängen λ_i durchstrahlt. Die Absolutwerte der Massen m' der Flüssigkeit und m'' des Dampfes ergeben sich aus den Dichten ρ'' und ρ' im thermischen Zustandspunkt des Fluids 3. Das Gleichungssystem wird innerhalb einer Auswerteeinheit 14 iterativ gelöst, wobei mindestens zwei Iterationsschritte notwendig sind, oder ein festzulegendes Konvergenzkriterium erreicht ist. Die Dichten ρ'' und ρ' sowie der thermische Zustandspunkt des Fluids 3 sind zunächst unbekannt, da der Ölmassenanteil x_Öl unbekannt ist, und müssen abgeschätzt werden. Nach mehreren Iterationsschritten nähert sich die Lösung der exakten Lösung an. Die Leitung 2 ist im Bereich des Systems 1 als ein universal einsetzbares Element mit genormten Anschlussstellen, insbesondere als ein Abschnitt eines Rohres, ausgebildet. Das System 1 kann jedoch ebenso an anderen geeigneten Stellen im Kältemittelkreislauf ausgebildet sein.The system 1 for determining the mole fractions and the mass fractions of the phases of each component and the temperature of a fluid 3 is in 1 also shown in an enlarged view. For determining the vapor mass fraction x '' or the mass fraction of the liquid x 'of the fluid 3 , in particular the refrigerant or the refrigerant mixture x '' = 1 - x '= m''/m' + m '' = m '' / m '/ 1 + m''/m' or the _oil mass fraction x _oil

becomes a section of the line 2 with within the line 2 in the flow direction 4 flowing fluid 3 Trained sample space from a jet 6 a radiation source 5 , in particular a light beam 6 from a light source 5 , irradiated with fixed wavelengths λ _i . The absolute values of the masses m 'of the liquid and m''of the vapor are given by the densities ρ''andρ' in the thermal state point of the fluid 3 , The equation system is within an evaluation unit 14 solved iteratively, wherein at least two iteration steps are necessary, or a convergence criterion to be established is reached. The densities ρ '' and ρ 'and the thermal state point of the fluid 3 are initially unknown, since the _oil mass fraction x _{oil is} unknown, and must be estimated. After several iterations, the solution approaches the exact solution. The administration 2 is in the range of the system 1 as a universally applicable element with standardized connection points, in particular as a section of a tube formed. The system 1 However, it may also be formed at other suitable locations in the refrigerant circuit.

The light source 5 is arranged such that the light beam 6 along the beam path to a detector 7 is aligned. When the sample chamber is irradiated, it comes along the beam path of the light beam 6 to interactions between the light beam 6 and the components and / or phases of the fluid 3 in which the light is absorbed by the components and / or phases and the light intensity is thereby attenuated. The attenuation of the light beam 6 when passing through the fluid 3 is also called extinction. After the passage of the light beam 6 through the sample space are from the detector 7 Transmission light intensities I _sample (ν _i ) taken as a transmission light spectrum and converted into an electrical signal. The electrical signal is sent to the evaluation unit ( 14 ) and from the evaluation unit ( 14 ) analyzed.

welche mit der Nullabsorbanz A_Null(λ_Null) zu ΔA_i(λ_i) als Offset-Verschiebung korrigiert werden. Die Absorbanzverteilung ΔA(λ_i) und/oder die Maxima der Absorbanzen ΔA(λ_i) sind bei spezifischen Wellenlängen λ_i oder Wellenlängenintervallen für bestimmte Stoffmengen einer Komponente in einer Phase und bei einer Temperatur repräsentativ. Eine Absorbanzbande ΔA entspricht dabei dem Kurvenverlauf der Absorbanz ΔA(λ_i) mit einem lokalen Maximum zwischen zwei lokalen Minima. Mit Hilfe von Vergleichen von Absorbanzen ΔA(λ_i) mit Spektralverteilungen, welche für bekannte Stoffmengen und Temperaturen vorbestimmt und beispielsweise in einer Datenbank abrufbar hinterlegt sind, können die Stoffmengen der Komponenten und Phasen sowie die vorliegende Temperatur bestimmt werden.The transmission light spectrum has a characteristic distribution of the radiation intensity or transmission light intensity I _sample (v _i ), which is dependent on the respective mass fraction or molar fraction and on the temperature. At a fixed optical length, such as the inner diameter d of the conduit 2 , is by means of a radiation splitter in the light source 5 and an additional detector, in particular a photodetector, simultaneously a reference radiation intensity I ₀ (ν _i ), also referred to as background light intensity determined. Alternatively, the reference radiation intensity I ₀ (ν _i ) by a single measurement of the light beam 6 determined by the unencumbered sample space and then in the evaluation 14 saved. Thus, the radiation source-independent and detector-independent absorbance or absorbance distribution A _i (λ _i ) can be calculated:

which are corrected with the _zero absorbance A _zero (λ _zero ) to ΔA _i (λ _i ) as an offset shift. The absorbance distribution ΔA (λ _i ) and / or the maxima of the absorbances ΔA (λ _i ) are representative at specific wavelengths λ _i or wavelength intervals for particular molar amounts of a component in a phase and at a temperature. An absorbance band ΔA corresponds to the curve of the absorbance ΔA (λ _i ) with a local maximum between two local minima. With the aid of comparisons of absorbances ΔA (λ _i ) with spectral distributions, which are predetermined for known substance quantities and temperatures and stored, for example, in a database, the substance quantities of the components and phases as well as the present temperature can be determined.

The results can be displayed on a display element 11 reproduced and / or passed on to a control system of an installation.

As well as in 2 , which discloses a scheme for determining the mole fractions and the mass fractions of the phases as well as the components and temperature of a clean fluid or a fluid mixture, the light beam passes through 6 the sample space and thus the fluid 3 advantageous in a direction which is perpendicular to the flow direction 4 of the fluid 3 is aligned, and is detected by the detector 7 added. The light beam 6 occurs through an optical window 12 into the sample room of the pipe 2 on and off the rehearsal room again. The light beam 6 Penetrates the circular cylindrical line 2 advantageously along the diameter to obtain a representative mean of the total flow. For signal amplification, the light beam 6 , For example, via a mirror assembly, the sample space also penetrate several times. The optical windows 12 are protected against fogging at fluid temperatures below the ambient temperature, preferably designed to be heated in order to avoid a falsification of the measured values due to a possible liquid film formation.

In the method for determining the vapor mass fraction x '', the mass fraction of the liquid x 'of the refrigerant or the refrigerant mixture, the _oil mass fraction x _oil and the temperature is the integral mean of the concentrations as molar proportions along the light beam 6 when penetrating the composite as a multi-phase mixture or as a mixture fluid 3 determined within the sample space. The mole fractions become with the help of the molar mass M all in the system 1 components are converted into mass fractions. When determining the vapor mass fraction x '' and the mass fraction of the liquid x 'of the refrigerant or the refrigerant mixture is the signal to be measured from the local distribution of the liquid components on the beam path through the sample space and thus also the size of the drops of the liquid 3a independently.

The number of phases or components present are at least z monochromatic light sources 5 formed with the wavelengths λ _1, λ ₂ ... λ _z. Where: z = K ₁ + 2 · K ₂ + 1, where K _{1 is} the number of components to be detected, which occur only in an aggregate state, that is to say oil, and K _{2 is} the number of components to be detected, which at the same time exist as liquid and vapor. Alternatively, one or more polychromatic light sources may be used 5 be used, which emit light as a radiation source together with all the required wavelengths λ _i . To set a baseline and account for scattering effects is for the light sources 5 to provide a wavelength, which with none of the present components or phases of the fluid 3 interacts. The wavelength λ is indirectly proportional to the wave number ν and proportional to the frequency f of the light source 5 emitted light beam 6 : ν ~ 1 / λ ~ f.

The vapor mass fraction x "is, in the case of a pure fluid 3 , in particular a refrigerant from a component, on the ratio of the mass or the amount of substance of the gaseous phase of the fluid 3 to Mass or amount of substance of the total, composed of liquid and gaseous phase fluid 3 Are defined: x '' = 1 - x '= m''/m' + m '' = m '' / m '/ 1 + m''/m' = n '' / n '+ n''=n'' / n '/ 1 + n''/n'

The vapor mass fraction x '' and the _oil mass fraction x _{oil of} the fluid 3 , In particular, a refrigerant-oil mixture, which through the line 2 or another component of the refrigerant circuit flows, with the aid of different rotational vibration spectra, that is to say transmission light spectra or absorbance distributions A, the phases or substances of the fluid 3 certainly. Here, the determination of the vapor mass fraction x '' based on differences in the interactions between electromagnetic radiation and the molecules of a substance in the gas phase and in the liquid phase, which is also in the 3a and 3b as well as determining the _oil mass fraction x _oil on differences in the interactions between electromagnetic radiation and the different substances in the fluid 3 , what in 4 is shown.

The background light spectrum is determined in the sample space to determine the substance quantities or the substance amount fractions and the mass fractions as well as the temperature. In this case, the sample space or a room with identical geometric dimensions is not with the fluid to be examined 3 but merely acted upon by an infrared-active inactive in the spectral range to be examined fluid, which does not interact with frequencies of infrared electromagnetic radiation, which should be used to evaluate the measured variables to be determined. The sample space is filled, for example, with dry air. When determining the radiation source and detector dependent dependent backlight spectrum of each is assigned to be examined wavelength λ _i or wave number ν _i of the light spectrum, a light intensity I ₀ (ν _i) as background light intensity.

According to alternative methods, the background light intensity I ₀ (ν _i ) either by a single measurement of the light beam 6 through the unbuffered sample space, that is, for example, before filling the system or the refrigerant circuit, recorded and in the evaluation 14 or the background light intensity I ₀ (ν _i ) is with a part of the light beam guided by a bypass to the sample space 6 certainly, like 2 evident. The bypass has a sample room same room 13 with the sample space identical geometric dimensions, in particular an identical optical length on. The sample room same room 13 is acted upon by an infra-red light inactive in the spectral range to be examined fluid. The measurements in the rehearsal room and in the same room 13 done simultaneously.

During operation of the refrigerant circuit is the sample space with the fluid 3 charged and is from the fluid 3 flows through. The transmission light spectrum is recorded and assigned to each specific wavelength λ _i or wavenumber ν _{i of} the light spectrum a light intensity I _sample (ν) as transmission light intensity. The _sample light intensities I (ν) are attenuated spektralabhängig by the absorption of photons by the molecules. Since certain wavelengths λ _i or wavenumbers ν _i can interact only with certain substances or substances in specific states of aggregation, their respective light extinction is used according to the method of quantitative infrared spectroscopy for determining the concentrations.

From the transmission light intensity I _sample (ν _i ) and the background light intensity I ₀ (ν _i ), for each specific wavelength λ _i or wavenumber ν _i, an absorbance A becomes a measure of the attenuation of the light intensity during the transmission of the light beam 6 determined by the sample space, which is independent of the spectral sensitivity of the radiation source 5 and the detector 7 is.

With the absorbance A, a physical quantity is available, which is directly proportional to the number of particles or substance quantity n of the gas phase or the phase of the fluid of a component via the Lambert-Beersche law. The measuring criterion for each phase of a component is the attenuation of the light intensity as the absorbance ΔA (λ) of at least one frequency f or wavelength λ or wavenumber ν to be determined, which depends exclusively on this phase of a component and is offset-corrected.

einer Bande, welche nur von einer Phase eines Stoffes hervorgerufen wird, proportional zur Stoffmenge n der mit dieser Wellenlänge λ_i wechselwirkenden Phase des Stoffes. Dabei entspricht ε dem Extinktionskoeffizenten und d als optische Länge dem Innendurchmessers der Leitung 2 als Abmessung des Probenraums sowie dem vom Lichtstrahl 6 durch den Probenraum zurückgelegten Weg.After calibration and comparison with a normal, the steam mass fraction x '' and the mass fraction of the liquid x 'and the _oil mass fraction x _oil can be determined as the measured variable. According to Lambert-Beer's law, the absorbance is A

a band which is caused only by one phase of a substance, proportional to the amount of substance n of the phase of the substance interacting with this wavelength λ _i . In this case, ε corresponds to the extinction coefficient and d as optical length to the inner diameter of the line 2 as a dimension of the sample space as well as of the light beam 6 path traveled through the sample room.

The offset-corrected absorbances .DELTA.A (λ _i) are correlated in accordance with the Lambert-Beer's law with each of the molar amount of a phase of a substance, wherein the proportionality factors for different wavelengths are λ different.

For evaluation, as from the 3a and 3b shows advantageous absorbances ΔA _{i used} at wavelengths λ _i , in which the light extinction as attenuation of the light intensity I by the liquid phase of the fluid 3 low and by the gaseous phase of the fluid 3 is large and vice versa, so that in each case of exactly one phase of a Kompenente an absorbance A _{i is} caused. Likewise, absorbances A _i at wavelengths λ _i are used for the evaluation, in which the light extinction through the respective substance, for example the oil of the refrigerant-oil mixture, is large. Thus, in the case of a refrigerant-oil mixture with one component, three signals .DELTA.A _gas , .DELTA.A _liquid and .DELTA.A _oil can be determined, which in a direct functional relationship to the variables to be determined temperature, _oil mass fraction x _oil and vapor mass fraction x '' the refrigerant or the refrigerant mixture and the thermal state point of the fluid 3 establish.

Since the absolute values of the absorbances ΔA _i of the optical length d and the material according to the Boltzmann distribution also depend on the temperature, the temperature of the fluid 3 at a constant optical length d either from the absorbance ΔA _gas or the absorbance ΔA _liquid can be determined. From a ratio or several ratios of two characteristic absorbances ΔA _gas and ΔA _liquid , the vapor mass fraction x "or the _oil mass fraction x _{oil can be determined} from the absolute value of an absorbance or of several absorbances ΔA.

The selection of the for each substance of the mixture or each phase of the fluid 3 to be evaluated absorption band .DELTA.A _i (λ _i ), consisting of a fundamental or overtone or a combination band of at least one molecular vibration, taking into account the inner diameter d of the line 2 , which corresponds to the optical length d of the Lambert-Beer law, the present temperature range and the density of the gas phase so that the slope of the calibration line, according to the quantitative infrared spectroscopy, is in an optimal range, which in turn the sensitivity of the system 1 sets. The molar mass fractions and the mass fractions of the components as well as the phases of the components and the temperature are determined with light in the wavelength range of infrared light. The method may be based on the fundamental vibrations of the molecular vibrations using mid-infrared radiation sources and detectors, or the method is used in the frequency range of the overtones or the combined bands of the molecular vibrations using the near-infrared radiation sources and detectors.

As light sources 5 It is advantageous to use monochromatic semiconductor laser diodes or polychromatic light sources with grating monochromators or filters. As detectors 7 For example, photodiodes can serve.

In the 3a and 3b Two concrete evaluation options of the rotational vibration spectra for signal extraction of the vapor mass content and the temperature of a wet steam are shown. The representation after 3a is based on the shift of the wavelength or the wave number of the stretching vibration band Δν = ν ₂ - ν _{1 of} a refrigerant between the gas phase and the liquid phase. In 3b the resolution of the rotational fine structure between the liquid phase and the gas phase or the fine spectral structure of the rotational vibration bands is used. Within the gas phase, the molecules rotate undisturbed. The quantization of the rotational energy, described by quantum mechanics, produces a jagged rotational fine structure typical of the gas phase. A so-called tine stands in each case for the combination of a rotation transition and at least one vibration transition as the frequency of the center of the band with several pronounced maxima for a vibration band. During the phase of the liquid, the molecules mutually interfere with each other during the rotation, which widens and merges the discrete quantum-mechanically allowed energy levels to let. The collision rate of the molecules is very high, the rotational movements are limited. It causes a tumbling motion of the molecules, which results in a blurring of the rotational energy levels, thus widening the rotational fine structure and growing into continuous curves. This gives the broad curve for spectra of the phase of the liquid with a maximum in a vibrational band. In the fine rotational structure of a vibrational band within the gas phase, each rotational vibration transition is pronounced as such in the form of a so-called spike, that is to say a narrow band with a maximum in the red in the rotational vibration spectrum. In liquids, the rotation bands spread so that each vibration transition has only one maximum. Within the gas phase, therefore, the fine rotational structure of an infrared spectrum is still resolved, while due to the high intermolecular interaction rates, infrared spectra of the liquids exhibit monotonous broad bands of one maximum each.

The two absorbances ΔA _gas and ΔA _liquid are each caused exclusively by one phase of the refrigerant. The ratio of the absorbances ΔA _gas / ΔA _liquid can be calculated in each case from the light attenuations recorded in the diagrams. A spectrally resolving measurement is not necessarily required. The absolute values of the absorbances ΔA _gas and ΔA _liquid associated with the two states of aggregation can likewise be used to measure the temperature so that the absolute values ΔA _gas and ΔA _{liquid have, in} addition to their ratio, further signal information.

At the in 3a shown evaluation principle may advantageously be a broadband light source 5 can be used because the center of the stretch band between liquid and gaseous phase is shifted by a few hundred wave numbers ν, which brings a corresponding cost advantage. This in 3b On the other hand, the scheme shown requires particularly narrow-band light sources 5 with correspondingly higher costs. The advantage of the method 3b lies in the ability to perform multiple averaging measurements between different rotational vibration bands to minimize random measurement errors and increase accuracy.

From both methods, the ratio of the absorbances ΔA _gas / ΔA _{liquid can be determined} as a signal from z monochromatic measurements, but at least two measurements. The signal ΔA _gas / ΔA _liquid is directly proportional to the ratio of the two phases of the fluid according to Lambert-Beer's law 3

The vapor mass fraction x '' of the fluid 3 , In particular of the refrigerant is known to off x '' = n '' / n '/ 1 + n''/n' calculated. In the case of several components of a refrigerant _mixture, at least one ratio ΔA _gas / ΔA _liquid must be determined for each component in order to be able to determine the substance quantity or the molar concentration of the two phases of the component.

As well as from the 3a and 3b shows, the rotational fine structure of a vibrational band is resolved within the gas phase. In contrast, each vibration mode in the fluid causes a smooth fluid band in the infrared spectrum. In addition, the band center of the oscillations of the liquid molecules compared to the gas phase by several hundred wavenumbers ν in the direction of the wavenumbers red light shifted, also referred to as redshift, which is based on the difference of the wavenumbers ν _{2 of} the band center of the vibrations of the molecules of the liquid phase and the wavenumbers ν _{1 of} the band center of the vibrations of the molecules of the gas phase 3a is apparent. Due to the redshift of the stretching vibrations by about 300 cm ^-1 , at least part of the gas band and the liquid band are separated in the spectrum. The fundamental tones of the stretching vibrations in gas phases and liquid do not overlap. The band center indicates a pure vibrational transition at which the vibrational state of a molecule changes and the rotational state of the molecule remains constant. The band center shifts when the vibrational frequency of a molecule changes, for example, at a phase transition between liquid and gaseous. In 3a the frequencies of two radiation sources ν ₁ and ν ₂ to be detected and evaluated are identified. The weakening of the Light intensity of the light source 5 due to the wet steam as multiphase mixture, only the amount of substance of the gas phase depends on ν ₁ . Thus ΔA _ν1 = ΔA _{gas is} proportional to n ''. At ν ₂ , the light intensity of the light source 5 attenuated by the wet vapor of the number of molecules of the phase of the liquid and ΔA _ν2 = ΔA _liquid is proportional to n '. In 3b The signal extraction from two monochromatic measurements in a rotational fine structure is shown schematically. According to Lambert-Beer's law, the molar mass of the liquid phase n 'is proportional to the absorbance ΔA _liquid and the molar amount of the gas phase n "is proportional to the absorbance ΔA _gas . The light of a very narrow band light source 5 with the frequency ν ₂ interacts exclusively with the phase of the liquid and not with the gas phase. The absorbance ΔA _liquid at the frequency ν ₂ is proportional to the number of liquid molecules in the sample space. The frequency ν ₁ , in comparison, interacts with the particles of the gas phase and the particles of the phase of the liquid. The light extinction results from the sum of the attenuation of the light intensity caused by the single-phase amounts of substance ΔA _ν1 = ΔA _gas + ΔA _liquid .

ΔA _ν1 is thus proportional to the total molar amount n '' + n '. The rays of light 6 the two light sources 5 penetrate the sample space on the same trajectories. According to Lambert-Beer's law:

4 specifically shows the rotational vibration spectra of a refrigerant and a refrigerator oil in each liquid phase. In this case, at least one band of each component and phase are superimposed with no band of the other component or phase in order to be able to define a measurement signal for determining the respective amount of substance or the respective molar fraction.

If the two-phase fluid 3 , In addition, an oil content in liquid form, the amount of substance of the oil n _oil with a further attenuation of the light beam 6 ΔA _oil (ν _oil ) of a monochromatic radiation of the radiation source 5 with the wave number ν _oil at the transmission through the flow of the fluid 3 be determined. Neither the evaluated nor another oil vibration band should be evaluated with the vibration band of the fluid to be evaluated 3 overlap. Then the absorbance ΔA is _oil (ν _oil ) of the radiation source absorbed by the molecules of the oil 5 the frequency ν _{oil is} directly proportional to the amount of substance n _oil in the flow of the fluid 3 contained oil and the _oil mass fraction x _oil is determinable. With the aid of the molar masses and densities of all components of the fluid 3 the quantities of substances or the proportions of substances can be converted into mass concentrations. The densities are in the evaluation unit 14 to determine stored state function.

The _oil mass fraction x _oil can also be determined if the vapor content x '' of the fluid 3 Zero is and therefore the fluid 3 thus is present as a mixture of liquid and oil only. The measurement is also possible if, for example, the refrigerant-oil mixture forms a miscibility gap as a system, thus having two separate liquid phases and one gas phase. The prerequisite for the application of the measurement principle is the exact knowledge of the vibration spectra of the two substances, that is, for example, the refrigerant and the oil to select appropriate spectral ranges and to exclude band overlaps can. In addition, for each substance and each phase, a calibration of the absorbances ΔA and the ratios of the absorbances depends on the respective substance quantities or the temperature and an equation of state for the evaluation of the thermal state point, for example for the calculation of the densities ρ, the specific enthalpies h and Entropies s, deposit.

The two concrete evaluation options can be used for several wavelengths λ or wavelength ranges independently or combined, whereby a higher accuracy of determining the mass components and the temperature can be achieved.

In addition to those in the 3a . 3b and 4 also a multivariant calibration is possible, wherein for the required spectrally resolving measurement, a greater device-technical effort is required. The multivariable calibration involves a complicated mathematical algorithm, which makes it possible to determine from a spectrum of previously recorded correlations mole fractions and / or temperatures when the bands of two different components to each other, as opposed to the representation of 4 overlay each other.

LIST OF REFERENCE NUMBERS

1

system

2

management

3

fluid

3a

Drop of liquid

3b

oil drops

4

Flow direction fluid 3

5

Radiation source light source

6

-Ray beam

7

detector

8th

expansion element

9

Heat exchanger, evaporator

10

compressor

11

display element

12

optical window

13

sample room same room

14

evaluation

A

Absorbance, absorbance distribution, absorption band

.DELTA.A

Offset-corrected absolute value of the absorbance A to take into account the baseline shift

D

steam

d

Inside diameter pipe 2 , optical length

Fl

liquid

f

frequency

H

enthalpy

I

Light intensity

I ₀ (ν)

Backlight intensity, reference radiation intensity

I _sample (ν)

Transmission light intensity

m

Dimensions

m '

Mass liquid

m ''

Mass of steam

M

molar mass

n

amount of substance

n '

Quantity of fluid

n ''

Amount of substance steam

p

print

s

entropy

x '

Mass fraction of liquid

x ''

Steam mass fraction

z

Number of phases

Q.

Heat-cooling capacity Extinction coefficient

λ

wavelength

ν

wavenumber

ν ₁

the band center of the oscillations of the molecules of the liquid phase

v ₂

the band center of the vibrations of the molecules of the gas phase

ρ '

Dense liquid Dense vapor

Claims (15)

System ( 1 ) for determining molar proportions and mass fractions as well as the temperature and the thermal state point of a fluid ( 3 ), comprising: A sample space with at least one optical window ( 12 ), which of the fluid ( 3 ), - at least one radiation source ( 5 ), which a beam ( 6 ), - at least one detector ( 7 ), which absorbs radiation intensities as a radiation spectrum and converts them into electrical signals, and - an evaluation unit ( 14 ), which is configured in such a way that the detector ( 7 ) to receive and analyze signals generated, the radiation source ( 5 ) and the detector ( 7 ) to each other and to the at least one optical window ( 12 ) of the sample space are aligned, that of the radiation source ( 5 ) emitted beam ( 6 ) enters the sample space and exits the sample space and on exiting the sample space on the detector ( 7 ). System ( 1 ) according to claim 1, characterized in that - an optical window ( 12 ) and a reflection device are formed, wherein the of the radiation source ( 5 ) emitted beam ( 6 ) through the optical window ( 12 ) enters the sample space, is reflected at the reflection device and through the optical window ( 12 ) exits the sample space, or - at least two optical fenters ( 12 ) are formed, wherein the of the radiation source ( 5 ) emitted beam ( 6 ) through a first optical window ( 12 ) enters the sample space and through a second optical window ( 12 ) exits the sample space System ( 1 ) according to claim 1 or 2, characterized in that the radiation source ( 5 ) and the detector ( 7 ) are arranged in such a way and aligned with each other on the sample space, that the beam ( 6 ) the sample space and the fluid ( 3 ) penetrates in a direction which is perpendicular to a flow direction ( 4 ) of the fluid ( 3 ) is aligned. System ( 1 ) according to one of claims 1 to 3, characterized in that the sample space within a conduit ( 2 ), wherein the line ( 2 ) has a circular cylindrical shape and the cross section has an inner diameter (d). System ( 1 ) according to claim 4, characterized in that the radiation source ( 5 ) and the detector ( 7 ) are arranged aligned with each other and to the sample space such that the beam ( 6 ) the circular cylindrical conduit ( 2 ) penetrates along the diameter (d). System ( 1 ) according to one of claims 1 to 5, characterized in that a bypass with a sample room same space ( 13 ), a radiation divider and a detector ( 7 ), the sample space being the same ( 13 ) has identical geometrical dimensions to the sample space. System ( 1 ) according to one of claims 1 to 6, characterized in that the at least one radiation source ( 5 ) is formed as a light source, which is a light beam ( 6 ) having at least one predetermined wavelength (λ) emitted. System ( 1 ) according to claim 7, characterized in that - a plurality of monochromatic light sources ( 5 ) or - at least one polychromatic light source ( 5 ) is formed, which emits light having different predetermined wavelengths (λ). Method for determining molar mass fractions and mass fractions as well as the temperature and the thermal state point of a fluid ( 3 ) with a system ( 1 ) according to one of claims 1 to 8, wherein at least one of at least one radiation source ( 5 ) into one with the fluid ( 3 ) acted upon sample space emitted beam ( 6 ) at fixed wavelengths after passing the sample space through at least one detector ( 7 ), comprising the following steps: - determining reference radiation intensities I ₀ (ν _i ), - capturing a radiation spectrum by the at least one detector ( 7 ), Wherein a number of specific wavelengths radiation intensities I _sample (be assigned to i ν _i), and converting the received radiation intensities into electrical signals, - transmitting the electrical signals (to an evaluation unit 14 ) and analyzing the signals within the evaluation unit ( 14 Determining radiation intensities I _sample (v _i ), determining an absorbance distribution A (λ ₁ ) from the radiation intensities I _sample (v _i ) and the associated reference radiation intensities I ₀ (v _i ) for i specific wavelengths, Determining at least one _zero absorbance A _zero (λ _zero ), wherein photons of wavelength λ _{zero are} absorbed by none of the components of the fluid to be investigated, determining mass fractions and / or mass fractions of the components and their phases of the fluid ( 3 ), based on the absorbance distribution A (λ _i ) and the ratio of characteristic absolute values of the absorbances A, - determining the temperature of the fluid ( 3 ), based on the absorbance distribution A (λ _i ) and the ratio of characteristic absolute values of the absorbances A, and - determining the thermal state point with a in the evaluation unit ( 14 ) stored state equation. A method according to claim 9, characterized in that the reference radiation intensities - with a single measurement of the beam ( 6 ) determined by the unbound sample space and then in the evaluation unit ( 14 ) or - be determined simultaneously with the radiation intensities, with one in the beam source ( 5 ) arranged beam splitter by a sample room same space ( 13 ) guided beam ( 6 ) impinges on a detector, the sample space being the same ( 13 ) is formed with identical geometrical dimensions as the sample space and is acted upon by an infrared-active in the spectral range to be examined fluid. A method according to claim 9 or 10, characterized in that a baseline is determined, wherein for the beam sources ( 5 ) is provided which does not interfere with any of the components or phases of the fluid ( 3 ) interacts. Method according to one of claims 9 to 11, characterized in that at least a mole fraction and the temperature of the fluid ( 3 ) are determined from rotational vibration spectra, wherein the evaluation is based on the shift of the wavelength of the stretching vibration band between two phases and / or on the resolution of the rotational fine structure of two phases and / or vibrations of hydrogen bonds. Method according to one of claims 9 to 12 for controlling a refrigerant circuit, wherein the refrigerant circuit in the flow direction of the fluid ( 3 ) at least one expansion organ ( 8th ), at least one heat exchanger operated as an evaporator ( 9 ) and at least one compressor ( 10 ), the system ( 1 ) in the flow direction of the fluid ( 3 ) after a heat exchanger ( 9 ) and in front of a compressor ( 10 ) and wherein the system ( 1 ) certain values are used as a controlled variable. A method according to claim 13, characterized in that with the system ( 1 ) certain proportions by mass, mass fractions and the temperature and / or the thermal state point of the fluid ( 3 ) as a control variable for controlling an opening degree of the expansion element ( 8th ) be used. Method according to claim 13 or 14, characterized in that a system ( 1 ) in the flow direction of the fluid ( 3 ) after a heat exchanger operated as a condenser and before the expansion element ( 8th ), wherein the circulating mass fractions of the flowing fluid ( 3 ) and that the local mass fractions of the fluid ( 3 ) between the heat exchanger ( 9 ) and the compressor ( 10 ).

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