DE102014103106B4 - Steam jet refrigeration plant with two working media - Google Patents

Abstract

Steam jet cooling system with a propellant of a higher molecular weight substance or mixture of substances and a suction medium of a low molecular weight substance or mixture. The propellant flow and the suction medium flow run in separate circuits and combine at a jet pump (2), which works very effectively because of the working media used.

Description

The invention relates to a steam jet refrigeration system for refrigerated consumers such as residential and industrial buildings, warehouses and cold rooms for food.

Steam chillers are known per se ( DE 637 689 . DE 684 111 . DE 861 699 ) And contain a steam generator for the supply of motive steam, one or more jet pumps or ejectors for generating a suction gas stream from a cold evaporator, from which the cooling consumer is supplied with cooling media, and a condenser, in which the working medium water is deposited, if necessary the To be supplied to steam generator. An advantage of such water vapor chillers over other types of chillers is the small number of required aggregates that do not require rotating parts except the water pump for pumping the water into the steam generator. The disadvantage, however, is the relatively low efficiency of such water vapor chillers as compared to adsorption chillers or absorption chillers.

By DE 1 186 885 is a steam jet refrigeration machine with combustible working fluid (propane) has become known to stand on the one hand as a refrigerant and blowing agent of the steam jet cooling machine and on the other hand, an internal combustion engine of a refrigerated truck.

The DE 10 2011 077 079 A1 represents a simply built steam jet refrigerator with an ionic liquid as a propellant.

The US 2010 0 126 212 A1 shows a cooling device with two fluids. The device comprises a heated boiling boiler, a jet pump, a cooled condenser and a cold evaporator, whose generated cold is supplied to the user. The gas of the first fluid produced in the boiler is mixed by means of the jet pump with saturated vapor of the second fluid. The two present in gaseous or vapor form fluids are separated in the condenser by cooling, after which the first fluid is fed as condensate back to the boiler and there is reheated. The second fluid is fed via an expansion valve to the cold evaporator. Due to the expansion of the second fluid heat is removed from the system, or generated cold. The first fluid was called perfluorocarbon and the second fluid was water.

Also the ES 2 014 791 A6 shows a cooling device in which two fluids are used. As a heat source, a solar system is exemplified.

The invention has for its object to provide a steam jet refrigeration plant with improved efficiency. Furthermore, the possibility should be created of making solar thermal energy directly available for the cooling of buildings, industrial halls, food and much more, when the cooling demand and the solar supply are high.

The inventively novel steam jet refrigeration plant builds on the principles of the known water vapor chillers with steam generator, jet pump, condenser and cold evaporator, but uses two different working media, namely a higher molecular weight substance or mixture for the propellant gas stream and a low molecular weight substance or mixture for the suction gas. The propellant may also consist of a substance or mixture with a lower enthalpy of vaporization compared to a substance or mixture with higher enthalpy of enthalpy of absorption of the suction medium.

The aim is to generate as high a massive pulse stream as possible with a given energy expenditure for the evaporation of the fluids. Furthermore, the highest possible evaporation enthalpy should be required on the suction side, because this represents the cold gain of the system. Most of the higher molecular weight gas at the same speed of the drive current will include the higher impulse and can also transfer. However, there may also be cases in which more energy is needed to vaporize the higher molecular weight material, so that in these cases the driving current does not consist of the higher molecular weight.

In order to remain simple in the language, we only speak in the following about the higher molecular weight drive current.

During operation of the jet pump, these gas streams mix in the mixing chamber and are deposited in the condenser. In order to be reused separately in the circulation of the motive stream or the suction stream, there is a separator for separating the propellant from the suction medium. The suction medium is fed to the cold evaporator, where it evaporates as a result of the negative pressure generated by the jet pump and thereby generates cold, which is supplied to the cooling consumer. The propellant is supplied to the steam generator, which generates a propellant gas flow for the jet pump. Since the jet pump works due to momentum exchange between the propellant gas stream and the suction gas stream, the operation with a higher molecular weight medium then runs more effectively than with comparatively similar media of the propellant gas stream and the suction gas stream. The high molecular propellant gas stream has a higher pulse density and can thus generate a higher negative pressure in the cold evaporator, resulting in more effective evaporation of the suction medium.

For the propellant gas medium and for the suction medium different circuits are provided, which are combined by the jet pump and form the mixture gas flow, which is divided as a result of a Separatoreinrichtung in the Saugmedienstrom and the propellant stream.

For purposes of recuperation of heat energy, heat energy is extracted from the mixture gas stream and supplied to the motive medium stream before it reaches the steam generator.

According to a preferred embodiment of the invention, the steam jet cooling system is operated with propellant medium and with suction medium, which can not or only slightly mix, are of different densities, different molecular masses and as different evaporation enthalpies. This facilitates separation of the propellant from the suction medium and the separator may form part of the condenser.

In the preferred steam jet cooling system, a high molecular weight, nonpolar substance or mixture of substances is used as the driving medium and a low molecular weight, polar substance or substance mixture is used as the suction medium. As the driving medium, an organic substance or mixture of substances from the group of hydrocarbons and water can be used as the suction medium. The propellant can be separated from the suction medium by a phase separator as Separatoreinrichtung.

It is also possible to select the propellant medium and the absorbent medium from miscible liquids which have very different boiling temperatures. In this case, the cold evaporator can form part of the separator device, because above all the suction medium in the cold evaporator at the prevailing negative pressure abiedet. In this case, ethylene glycol can be used as a propellant and heavier boiling component and water as a suction medium and lower boiling component. Based on the invention, preferably small steam jet refrigeration systems in the range of 1 to 50 KW are to be developed as a series product. But there are also large systems up to 1 MW conceivable and constructible. As drive energy and solar-derived steam, in particular steam, can be used. Therefore, as a heat source for operating the steam jet refrigeration system, a focusing solar system or a vacuum tube system or a flat collector system can be used as an integral part of the steam jet refrigeration system.

However, it is also possible to use industrially generated steam for the steam jet refrigeration system of the invention.

• - 1 eine Dampfstrahlkälteanlage in schematischer Darstellung und
• - 2 eine Wärmeenergie-Rückgewinnungseinrichtung in schematischer Darstellung.

An embodiment of the invention will be described with reference to the drawing. Showing:

• - 1 a steam jet refrigeration plant in a schematic representation and
• - 2 a thermal energy recovery device in a schematic representation.

The steam jet refrigeration plant has the following functional components: a steam generator 1 , a jet pump 2 , which can also symbolize a jet pump group, a condenser 3 , a separator 4 and a cold evaporator 5 , To operate the steam jet refrigeration plant is still a heat source 6 , which is symbolized here as a heating coil, and a heat sink 7 needed, which is shown here as a heat exchanger cooling box. At the steam jet refrigeration plant is still a cooling consumer 8th connected.

The plant is operated with two different work equipment, which are referred to as the driving medium and suction medium. The propellant is in a preferred embodiment of the invention of a higher molecular weight substance or mixture and the suction medium consists of a low molecular weight substance or mixture, which are predominantly present as liquids at low temperature and pressure and can be vaporized at elevated temperature or applied vacuum. The propellant may also consist of a substance or mixture of substances with a lower enthalpy of vaporization compared to the suction medium, which has a higher enthalpy of enthalpy of vaporization. For each of these working fluids, there is a different circuit, but located in the mixing chamber of the jet pump 2 to the condenser 3 unite to get in the separator 4 to separate again.

While 1 As a functional representation of the steam jet refrigeration system can be interpreted, there are in reality essentially two different ways of construction: The construction with two immiscible or only slightly miscible liquids as a working fluid and the construction with miscible fluids as a working fluid. These designs differ mainly in where the Separatoreinrichtung 4 is arranged. In the construction of immiscible liquids is the separator 4 inside the capacitor 3 arranged, while in the case of miscible liquids, the separator 4 within the cold evaporator 5 located.

In the case of non-miscible or only slightly miscible liquids of the propellant and the suction medium, these have different densities and also as different boiling temperatures. Such liquids form different layers in the condenser 3 so that the upper lighter layer through a suction media line 15 by means of a pump 15a in the cold evaporator 5 and the lower heavier layer through a drive media line 11 by means of a pump 14a in the steam generator 1 can be promoted. When in the steam jet refrigerator the condenser 3 above the steam generator 1 and the cold evaporator 5 can be arranged, the promotion of the lighter suction medium by gravity through the Saugmedienleitung 15 alone in the cold evaporator 5 take place while the heavier propellant from the pump 14a through the drive media line 11 in the steam generator 1 is directed.

In the embodiment with immiscible liquids, a high molecular weight nonpolar substance or substance mixture is used as the driving medium and a low molecular weight polar substance or substance mixture is used as the suction medium. As the driving medium is an organic substance or mixture of substances from the group of hydrocarbons into consideration, e.g. Pentane, hexane, heptane, octane, nonane or other similar in their effect substances such as diesel oil. Because of the low enthalpy of vaporization and the high molecular weight, in particular fluorocarbons or perfluorinated polyethers or a mixture of substances of both groups as well as other molecules with similar material data come into question. As a suction medium is mainly water or solar fluid into consideration, as this is used for operation in solar systems. The evaporation enthalpy of the propellant is much lower than the enthalpy of vaporization of polar substances, for example water. This means that the nonpolar substances can be evaporated in a multitude with an amount of heat that is needed for a simple amount of polar substances (water). With a kilowatt hour of energy you can vaporize 7 times the amount of octane, compared to water. This means that in principle less energy is required in the steam generator than when water is used as the driving medium. However, the enthalpy of enthalpy of evaporation still has to be calculated, which is needed to bring the propellant from the temperature in the condenser to the temperature in the steam generator. Since the proposed, non-polar substances in the gas stream have a lower speed of sound than water vapor, a larger mass flow is used to achieve the same pulse current (as in water), which achieves the same suction / cooling performance, as with water as a propellant. The consideration is thus still that in the proposed non-polar substances, the amount to be heated is greater than in the case of the use of water as a propellant. Thus, there are opposing effects of reducing the enthalpy of vaporization and increasing the heating energy, leaving a positive overall effect between them.

The positive effect leads to improvements in the efficiency of the steam jet refrigeration system. This is discussed using octane as the propellant and water as the absorbent medium. The octane propellant gas stream passes from the steam generator 1 with an absolute pressure of 1.5 bar in the jet pump 2 , which has a nozzle for accelerating the propellant gas flow up to 2 to 3 times the supersonic speed. Around the supersonic jet, a negative pressure develops, which extends into the cold evaporator 5 propagates and there to the boiling of the suction medium, here water, leads. The water vapor gets inside the jet pump 2 entrained with the propellant gas stream and the mixture gas stream thus formed passes into a downstream of the acceleration nozzle diffuser 12 , which delays the mixture gas flow and the condenser 3 absolute at about 60 mbar. This capacitor 3 is cooled, so that the two media octane and water are condensed out. The entire heat flow, which results from the cooling and liquefaction of the driving medium and the suction medium is through the heat sink 7 to ambient temperature or slightly dissipated.

The promotion of the suction medium, here water vapor, is effected by an exchange of pulses between the driving medium (octane) and the suction medium (water). It turns out that the high molecular propellant gas stream entrains the low molecular weight suction gas stream particularly effectively compared to the case where water vapor is used for both the propellant gas stream and the suction gas stream.

The heat balance of the system can be further improved by the fact that heat energy from the mixture gas flow to be cooled through the condenser 3 leading line 13 to the drive media stream through the drive media line 11 is transferred from the Separatoreinrichtung 4 to the steam generator 1 leads. 2 shows the scheme of such heat recovery. In addition, sample parameter values are entered. In the mixture gas line 13 is a heat exchanger 130 provided by circulation pipes 131 . 132 with another heat exchanger 110 is connected, the heat to the propellant in the Treibmedienleitung 11 transfers. However, it is also a simplified construction of heat transfer possible by the line section 11a the drive media line 11 and the line section 13a the mixture gas line 13 to each other as Heat exchangers are led, whereby by the pump 14a driven propellant stream heated after passing through the heat exchanger is supplied to the steam generator. In this way, a part of the otherwise required heating energy of the driving medium is saved, which otherwise from the heat source 6 would be applied in the whole. The efficiency of a plant, also referred to as the coefficient of performance / COP, can be determined by the measure of heat integration, as in 2 shown to be improved by about 20%.

Example:

In the front of the heat exchanger 130 located section 13a the mixture gas line 13 a mixture gas flow of 60.23 kg / h at 120.5 ° C is performed. In the section 13b the mixture gas line 13 after the heat exchanger 130 the mixture gas flow still has a temperature of 41 ° C. The propellant leaves the condenser 3 with a temperature of 35.5 ° C through the line section 11a in front of the heat exchanger 110 and leaves this with a temperature of 102.86 ° C at a flow rate of 56.19 kg / h of driving medium through the line section 11b the drive media line 11 to the steam generator 1 , Between the heat exchangers 130 and 110 a heat quantity Q. = 2.54 kW is transmitted.

How out 2 it can be seen, that of the heat exchanger 110 Transfer the available heating energy at 35.5 ° C to the propellant, ie the heating energy can be supplied at a lower temperature level, as it corresponds to the temperature level (120.5 ° C) at which the enthalpy of vaporization via the heat source 6 is supplied. Thus, it is understood by those skilled in the art that in the supply of a portion of the required energy at a lower temperature level, an advantage of the present steam jet refrigeration plant in combination with solar thermal systems is given. With a suitable choice of materials and the structure of the system efficiency increases by 50% can be achieved.

When using non or only slightly miscible liquids, the separator device 4 designed as a phase separator and within the capacitor 3 arranged. The mixture gas flow of the line 13 meets inside the capacitor 3 on cooled walls or a falling drop carpet or liquid strands or other dosage form of the cooling liquid coming from the heat sink 7 donated. The cooling takes place at ambient level, which is known to fluctuate. The cooling takes place in any case such that both liquids, the propellant and the suction medium, condense out and because of their low miscibility for the formation of two superimposed layers, via appropriate Treibmedienleitung 11 or via the suction media line 15 tapped and the steam generator 1 or the cold evaporator 5 can be supplied.

The invention is also applicable to miscible liquids for the propellant medium and the suction medium, if these liquids have boiling temperatures far apart. As a driving medium and heavier boiling component of ethylene glycol is called and called the suction medium and lower boiling component water. For this choice of working fluid, the functional unit "Separatoreinrichtung" in the cold evaporator 5 be moved. In this case, condensed mixture of propellant and suction medium from the condenser 3 in the cold evaporator 5 directed, where the separation of the suction medium from the driving medium by the different evaporation behavior of these two working medium. The lower boiling water forms water vapor from the jet pump 2 is sucked, while at the bottom of the cold evaporator vessel, the driving medium accumulates as a heavy boiling component and into the steam generator 1 is pumped or gets there by gravity. Otherwise, the operation with miscible liquids as working fluid corresponds to the operation with immiscible liquids as working fluid.

When selecting the propellant medium and the suction medium still plays the lowering of the vapor pressure of the propellant a role. This allows a large-volume nozzle in the jet pump 2 can be used, which is favorable in terms of avoiding friction losses of the flowing gas in the nozzle when the steam jet refrigeration system is to be built for a smaller power range. In the case of large-volume nozzles, the ratio between volume to surface is more favorable than with smaller nozzles. Thus, for steam jet refrigeration plants of smaller power (20-50 kW), easier manufacturability of the nozzle is expected with improved efficiency during use.

1 It is understood that in a real steam jet refrigeration plant also control and regulating devices are provided in order to set the required by the cooling load cooling capacity each. For this, the heat flow between the heat source 6 and the heat sink 7 be regulated or the demand control, for example, by turning on and off the jet pump 2 via a check valve 16 , Thus, electrical energy is required only to a small extent, namely for purposes of control / regulation or operation of pumps, if used (instead of gravity).

The steam jet refrigeration system can be used as a compact system in the production mode of a refrigerator, i. are made without flange connections between the parts of the device, but soldering or welding connections between the parts of the device are used to achieve a complete encapsulation. The complete encapsulation should not make it necessary to vent the device during its service life. The partial load behavior should be made possible by two-point control and heat storage. The control technology should be done on a microprocessor basis to be priced low.

• Keine beweglichen, Kälteenergie erzeugenden Teile. Dadurch ist ein wartungsfreier Betrieb möglich.

Compared with absorption chillers or adsorption chillers, the following advantages can be achieved with the new steam jet chiller:

• No moving, cold energy generating parts. This makes maintenance-free operation possible.

The plant is operated with thermal energy. Electrical energy is needed only for control / regulation to a small extent. The refrigerant used is water and environmentally friendly work equipment. The liquids used are conducted in a closed circuit. Thus, the environmental impact of the system in case of damage and disposal is much lower than in the absorption refrigeration and Adsorptionskälteanlagen.

Due to the simple design of the steam jet cooling system, significantly lower construction costs than series products are to be expected.

With a cooling capacity of 20 kW and a target value of COP of 0.5, a thermal heat flow of 40 kW is required. When using solar thermal systems as heat sources, such a required heat flow during the summer at the time of the largest cooling demand can be easily provided.

Claims (12)

Steam jet refrigeration system for refrigerated consumers (8), such as residential or industrial buildings, warehouses or cold storage rooms for foodstuffs, comprising: a heat source (6) for operating the steam jet refrigeration plant, - A steam generator (1) with propellant medium from a high molecular weight substance or mixture to a low molecular weight substance or mixture of a suction medium, or the propellant consists of a substance or mixture with lower enthalpy of vaporization compared to a substance or mixture with higher enthalpy of enthalpy of the suction medium, the propellant due to supplied heat to a propellant gas stream in the steam generator (1) is evaporated, - A jet pump (2) or jet pump group to entrain by means of the propellant gas stream a low molecular weight or with a higher enthalpy of vaporization suction gas stream and to promote the mixture gas flow thus formed from propellant and suction medium, a condenser (3) which receives the mixture gas stream and condenses its medium component, - Separatoreinrichtung (4) for separating the propellant medium from the suction medium and supply of the propellant to the steam generator (1) and supply of the suction medium in - A cold evaporator (5) from which the jet pump (2) withdraws the suction gas stream, which evaporates because of pressure reduction, the suction medium and cold is generated, which is the cooling consumer (8) can be fed, - In each case different circuits are provided for the propellant medium and for the suction medium, which combine in the jet pump (2) in a mixture gas line (13) to the mixture gas stream and at the Separatoreinrichtung (4) in a Saugmedienleitung (15) and a Treibmedienleitung ( 11), and - In which the mixture gas flow via a heat exchanger the Treibmedienstrom in heat exchange relationship to a heat exchanger (110) which leads via the Treibmedienleitung (11) to the steam generator (1). Steam jet refrigeration plant after Claim 1 wherein the propellant medium and the suction medium are not or only slightly miscible liquids, in addition to different molecular masses of different densities and also have different boiling temperatures as possible. Steam jet refrigeration plant according to one of Claims 1 to 2 in which a high molecular weight nonpolar substance or mixture of substances is used as the driving medium and a low molecular weight polar substance or substance mixture is used as the suction medium. Steam jet refrigeration plant after Claim 3 , Wherein the driving medium is an organic substance or mixture of substances selected from the group of hydrocarbons, fluorocarbons and perfluorinated polyether and water or solar fluid as the suction medium. Steam jet refrigeration plant after Claim 3 or 4 wherein the separator (4) is designed as a phase separator. Steam jet refrigeration plant after Claim 5 wherein the separator means forms part of the condenser (3). Steam jet refrigeration plant after Claim 1 wherein the propellant medium and the suction medium are miscible liquids, but have very different boiling temperatures, and wherein the cold evaporator (5) forms part of the separator device (4) by allowing the suction medium to settle. Steam jet refrigeration plant after Claim 7 , Ethylene glycol being used as a driving medium and as a heavy-boiling component and water as a suction medium and as a lower-boiling component. Steam jet refrigeration plant according to one of Claims 1 to 8th , wherein the heat source (6) is designed as a focusing solar system with water or solar fluid as a working medium. Steam jet refrigeration plant according to one of Claims 1 to 8th , wherein the heat source is designed as a vacuum tube system or vacuum flat-plate collector system with water or solar fluid as a working medium. Steam jet refrigeration plant according to one of Claims 1 to 8th , wherein the heat source is designed as a flat collector system with water or solar fluid as a working medium. Steam jet refrigeration plant according to one of Claims 1 to 8th , wherein the heat source includes industrially produced low-temperature water vapor.

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