DE102005032266A1 - Process for removing a gas from a heat pump and heat pump - Google Patents

Abstract

The invention relates to a method for discharging a gas from a heat pump (1), an inflow section (9), an outflow section (6) angled therefrom and a suction section (5) being formed in a pipeline system, which is connected to the inflow section (9) and the outflow section (6) is in communication, wherein in the process a solvent (8) is fed from the inflow section (9) into the outflow section (6) with the formation of contraction eddies, the gas to be discharged is taken up by the solvent (8) as a result of the contraction eddies and after draining through the drainage section (6) is discharged from the pipeline system, as well as a heat pump (1).

Description

The The invention relates to a method for removing a gas from a heat pump and a heat pump.

A heat pump serves the exchange of heat between a payload area and a buffer medium. Examples of heat pumps include room air conditioners and absorption refrigerators, where heat from Useful area, for example a living space or a refrigerator, transferred to a buffer medium becomes.

such Heat pumps usually include a refrigerant, which is different in a cycle process Physical states and temperature ranges goes through and due to alternating proximity to a utility area medium and exchanging energy in the form of heat with a buffer medium with these media, for example, using heat exchangers. In addition to the heat pump medium comprises an absorption heat pump usually also an absorbent, in which the heat pumping medium in a section of the heat pump called the absorber solved can be. Subsequently will heat exchanged between the working medium and the working area.

Out different reasons, For example, due to corrosion or leakage, can in the heat pump undesirable Gases, so-called foreign gases, emerge. These gases generally work negative for the thermodynamic properties of the heat pumping process out and lead ultimately to a reduction in the efficiency of the heat pump. About that can out the gases due to chemical reactions with the heat pump medium and / or with other parts of the heat pump and / or due a pressure build-up to injury the heat pump to lead. It is therefore great Meaning, these gases, if possible continuous and complete, from the heat pump dissipate.

For the discharge of Gases from heat pumps different procedures have already been proposed. In known Devices this is an external vacuum pump verwen det, which is put into operation at fixed intervals to the gases to extract from the different sections of the heat pump. These However, pumps are very cost-intensive and also sensitive to moisture.

It An auxiliary absorber can be used, which after the same Principle like the absorber, but at a relatively lower temperature level, works, and thus generates a suction pressure. This created so Relative negative pressure is used to suck in a gas and so on from the heat pump dissipate. The backflow of the Gas in the heat pump is by means of a standing liquid column in one Connecting pipe prevented. The auxiliary absorber works in parallel to the absorber of the heat pump. However, the suction in this case is below what can be reached by an external vacuum pump. Furthermore required operating the auxiliary absorber a certain energy, resulting in a Reduction of the efficiency and an increase of the irreversibilities of the heat pump leads.

Farther Devices are known in which jet pumps for suction a gas from a heat pump be used. Jet pumps use a propulsion jet from one liquid and generate according to the Bernoulli principle by means of a flow change in a suction chamber a local negative pressure. A flow change is generally achieved by flowing through a pipe constriction. The achievable with jet pumps minimum suction pressure is the vapor pressure of Motive jet liquid. additionally a mechanical vacuum pump may be provided for suction is used. Pure jet pump systems for extracting the gas could not be realized yet. Because the propulsion jet for the Generating the local negative pressure in the jet pump a reasonable Pressure, in this case a few hundred millibar (mbar) must be here the use of a pump required to drive the jet with the required Pumping power through the jet pump. Such additional However, pumps increase the energy requirements and the price of the device.

The invention

task The invention is a method for removing a gas from a Heat pump and a heat pump to disposal to provide a gas from an efficient and cost effective way heat pump dissipated can be.

The The object is achieved by a Method according to the independent Claim 1 and a heat pump after the independent Claim 10 solved.

According to the invention, a method for removing a gas from a heat pump is provided, wherein in a pipeline system, an inflow section, an outlet portion angled thereto and a suction portion are formed wel In the process, a solvent is supplied from the inflow section to the outflow section with the formation of contraction vortices, the dissipated gas is taken up by the solvent due to the contraction vortices and discharged from the pipeline system after draining through the outflow section becomes.

Opposite known Method for removing a gas from a heat pump the invention has the advantage that no device parts moves and thus signs of wear be avoided. The contraction vortices cause the gas in the solvent is recorded. For example, the gas may be in the solvent dissolve or it can be in the solvent vesicle form. By the discharge of the gas, a negative pressure forms in the intake section, whereby further gas from the piping system sucked into the intake becomes.

In an advantageous embodiment of the invention is provided that this solvent in the discharge section, which there as a gas / solvent mixed stream is present, driven by gravity is moved. This has the Advantage that no additional Pumping power for the suction of the solvent must be spent. It's falling thus, no, associated with using an additional pump, additional Cost and material costs. In an advantageous embodiment the invention becomes the solvent in the inflow section by means Gravity moves.

at an advantageous embodiment the invention becomes the solvent from the drainage section pumped out.

In A preferred embodiment of the invention is a flow rate in the inflow section regulated and thereby a discharge rate for the discharge of the Gas from the heat pump controlled. This has the advantage that the discharge rate the operating conditions the heat pump customized can be. For example, could the discharge of the gas can be made only in the presence of leakage. The discharge For example, it can be done at intervals.

In an advantageous embodiment The invention is used as a solvent Water used. this leads to to use a for harmless the environment Solvent, its disposal can be carried out in a simple way environmentally friendly can.

In An advantageous development of the invention is the solvent together with the to be discharged Gas discharged from the piping system. This has the advantage that this Gas without detours from the heat pump dissipated can be. There are thus no additional process steps needed for example, in the solvent taken out gas from the solvent.

advantageously, is used as a solvent in one embodiment the invention uses a working fluid of the heat pump. For this For example, part of the pipe system in the heat pump flowing Working fluid diverted by means of a branch element and the inlet section supplied become. It is omitted the need for the heat pump additional liquids to disposal to deliver. This eliminates many storage requirements and disposal of these additional Liquids.

The from the solvent absorbed gas is in an advantageous embodiment of the invention removed from the solvent by means of a separator. That has the advantage that the solvent subsequently essentially present in pure form and be reused can.

In A preferred embodiment of the invention is that from the solvent removed gas in a storage tank collected. Hereby is the possibility given the gas at a later date environmentally sound disposal.

advantageous versions of the invention in the dependent apparatus claims have the advantages listed in connection with the associated method claims accordingly.

Description of preferred embodiments

The Invention will be described below with reference to exemplary embodiments with reference on figures of a drawing closer explained. Hereby show:

1 a heat pump designed as an absorption chiller;

2 a vapor pressure diagram for water-lithium bromide solutions;

3 a suction device having a suction portion, an inflow portion and a drain portion;

4 a section of a heat pump with an absorber, a suction device and a separator;

5 a section of another heat pump with an absorber, a suction device and a separator;

6 a portion of another heat pump with a condenser and a suction device; and

7 a diagram illustrating the effect of a method for discharging a gas from a heat pump.

1 shows an embodiment of a heat pump 1 , which is referred to as absorption chiller. The heat pump 1 includes the following components: an evaporator 10 , an absorber 11 , an exporter 12 which is often referred to as a generator or desorber, and a capacitor 13 , In 1 are also other components such as pumps 14 . 15 , a solution heat exchanger 18 and throttle means 16 . 17 , For example, U-tubes shown. In the evaporator 10 becomes a heat pump medium 2 , For example, water, evaporated at low pressure. The pressure in the evaporator 10 in this case corresponds to the vapor pressure of the heat pump medium 2 at a temperature of about 5 ° C to 15 ° C. In doing so, the heat pumping medium withdraws 2 a working medium 20 For example, water, energy in the form of heat. This is done, for example, in that the evaporator 10 comprising a heat exchanger and that water of an air conditioning circuit of a building flows through the heat exchanger and is cooled there.

The vaporized heat pump medium 2 is then in the absorber 11 directed, what in 1 is illustrated with an arrow A. In the absorber 11 becomes the vaporized heat pump medium 2 absorbed by an absorbent, for example, a concentrated lithium bromide solution (LiBr solution) in an absorption process. The absorber 11 comprises a heat exchanger that is a buffer medium 21 is flowed through, which is at a medium temperature level. After that lies the heat pump medium 2 dissolved in the absorbent in a rich solution 22 in front. In the absorber 11 There is a pressure level, which is a pressure level in the evaporator 10 essentially resembles. The rich solution 22 is using a pump 15 to a higher pressure level in an exporter 12 pumped. The expeller 12 comprises a further heat exchanger, which is traversed for example by hot water or steam. In the expeller 12 becomes the heat pump medium 2 from the rich solution 22 evaporates and absorbs energy. In the expeller 12 remains a poor solution 23 back. The poor solution 23 has a lower concentration of dissolved heat pump medium 2 on, as the rich solution 22 , The poor solution 23 , which thus has a higher concentration of lithium bromide, is then available again for the absorption process.

The vaporized heat pump medium 2 gets into a capacitor 13 directed, what in 1 is illustrated with an arrow B. In the condenser 13 becomes the vaporized heat pump medium 2 liquefied and then using the throttle means 16 brought to a lower pressure level and into the evaporator 10 directed. With the throttle means 16 . 17 gas leaks in the heat pump 1 prevented by bringing flowing fluids from a high to a lower pressure level. The capacitor 13 comprises a heat exchanger, the buffer medium 21 is traversed at a medium temperature level, for example at ambient temperature. The pressure level in the condenser 13 and in the expeller 12 is the equilibrium pressure of the heat pump medium 2 specified during the condensation. Temperatures between about 25 ° C and about 40 ° C usually prevail there.

Absorption refrigeration systems can be operated with different substance pairs. Depending on the thermodynamic properties of these pairs of substances, the absorption refrigeration systems are operated in overpressure, for example in the case of the substance pair ammonia-water, or under reduced pressure, for example in the case of the substance pair water-lithium bromide. Heat pumps are used in the research area of cooling and building air conditioning 1 in which as heat pumping medium 2 Water and used as an absorbent lithium bromide are playing a prominent role.

2 shows a vapor pressure diagram for the substance pair water-lithium bromide. In the vapor pressure diagram are curves 31 each showing the pressure versus temperature for a particular mixing ratio of a water-lithium bromide solution. For example, it can be seen from the vapor pressure diagram that water, that is, a water-lithium bromide solution having a mixing ratio of 1.0, in the evaporator 11 can evaporate at a temperature of about 10 ° C and a pressure of 12mbar. The condensation in the condenser 13 can then take place, for example, at 36 ° C, and thus at a pressure of 59mbar. 12mbar and 59mbar are then the absolute pressure levels in the operation of such a heat pump 1 , In the vapor pressure diagram 30 is a process of a heat pump 1 to 1 schematically by means of a so-called plant characteristic curve 32 shown. Hiebei are thermodynamic states in which the water-lithium bromide solution in the evaporator 10 , in the absorber 11 , in the expeller 12 or in the condenser 13 is located, by means of letters V, A, G, K in the plant characteristic curve 32 characterized. Connecting lines between the States in the heat pump 1 occurring state changes.

The pressure in the evaporator 10 has a value where the heat pumping medium 2 already evaporated at a temperature of, for example, -15 ° C. The vaporized heat pump medium 2 will be in the absorber 11 dissolved in the absorbent, wherein a resulting heat with the buffer medium 21 is dissipated. The due to the dissolution of the heat pumping medium 2 in the absorbent rich solution 22 is by means of a pump 15 is promoted to a higher pressure level. By supplying driving heat at a temperature of, for example, 110 ° C, the vaporized heat pumping medium becomes 2 in the expeller 12 again from the rich solution 22 expelled, so that in the expeller 12 the absorbent now as a poor solution 23 is present. The expelled evaporated heat pump medium 2 becomes the capacitor 13 directed and there with the help of the buffer medium 21 brought to a temperature of about 30-40 ° C, resulting in liquefaction of the heat pumping medium 2 leads. After throttling the heat pumping medium 2 This is then ready again in the evaporator 10 to be evaporated. The in the expeller 12 resulting poor solution 23 is then passed over the solution heat exchanger 18 passed and finally the absorber 11 fed.

In the solution heat exchanger 18 gets out of the absorber 11 coming rich solution 22 by means of the expeller 12 coming, higher temperature, poor solution 23 preheated.

In an absorption refrigeration system, the fact that the heat pumping medium is utilized, as in a compression refrigeration system 2 has pressure-dependent boiling and melting points. In the case of a compression refrigeration system, an electrically operated compressor is used to increase the pressure of a refrigerant vapor to the pressure level of a capacitor. In contrast to this, in the case of a sorption refrigeration plant, a second absorption medium circuit is used for this purpose, with the refrigerant vapor being liquefied. Since the refrigerant vapor is then in solution, and thus has a smaller specific volume, it can be brought to a higher pressure with significantly lower electrical energy consumption.

The from the heat pump 1 included components evaporator 10 , Absorber 11 , Expeller 12 and capacitor 13 each comprise heat exchangers which transport heat between external, that is, outside a respective component flowing, and internal, that is, flowing within a respective component, media. The efficiency of heat transfer is, in the desired condensation and absorption processes, as in the condenser 13 and absorbers 11 take place, by the presence of undesirable gases, also called foreign gases, reduced. Performance losses of 50% are to be expected even with a foreign gas share of 3-5 vol.%. If, in addition, oxygen is part of the foreign gases, this can be combined with the solution of the heat pump medium 2 in the absorbent, for example in conjunction with the water-lithium bromide solution, to corrosion in the heat pump 1 leading to damage to the thermodynamic process as well as the lifetime of the system.

3 shows a suction device 3 with a suction section 5 , a drainage section 6 and an inflow section 9 , arrows 8th . 8th' . 8th'' in 3 indicate flow directions. The intake section 5 serves to a dissipated from the heat pump gas in the suction 3 respectively. Through the inflow section 9 becomes a solvent 8th in an area 7 the suction device 3 guided. In that area 7 form contraction vertebrae, which cause that in the area 7 located gas in the solvent 8th is recorded. In this case, the gas bubbles in the solvent 8th form. The gas could also, at least partially, in the solvent 8th to solve. The contraction vertebrae form, for example, in that the solvent 8th free in the drain section 6 falls. The vortex formation supporting measures may be the provision of baffles or lateral inflows.

According to 3 is the inflow section 9 at right angles to the discharge section 6 arranged. This promotes the formation of contraction vortices. The inflow section 9 but also with the drainage section 6 make another angle. For example, the suction device 3 Be formed Y-shaped. In addition, the intake section 5 one in the suction device 3 projecting pipe section (not shown) include. In the 3 have the intake section 5 , the inflow section 9 and the drainage section 6 same and uniform cross sections. However, the cross sections may be different for each section. In addition, it can be provided that the cross section changes along a section. In particular, a cross-sectional constriction in the area 7 be provided to promote the formation of contraction vertebrae.

After going through the area 7 the solvent flows 8th through the drainage section 6 it is in the area 7 absorbed gas takes. In the thus emptied area 7 is therefore due to the suction section 5 a negative pressure, which for a suction effect from the suction section 5 to the area 7 responsible for. Due to this suction further gas flows from the Absau gabschnitt 5 in the area 7 ,

In the Aubflußabschnitt 6 forms due to the from the inflow section 9 there flowing solvent 8th a column of liquid from the solvent 8th from, which by a liquid level in the discharge section 6 is limited to the top. The drainage section 6 acts as a downpipe. In this case, the strength of the suction at the suction depends 5 from the length of below the liquid level in the discharge section 6 extending liquid column from. The length of the liquid column can be selected by selecting the length of the discharge section 6 and the installation height of the suction device 3 determine.

The suction in the intake section 5 is based on a suction pressure which is at least as great as the vapor pressure of the solvent 8th , The vapor pressure of the solvent 8th However, it is lower than the one in the absorber 11 or in the condenser 12 prevailing pressure. The reason for this is the hypothermia that occurs during the condensation and absorption of the heat pump medium 2 occurs. The method can be applied without applying a pre-pressure only by means of the pressure, which is due to a height difference between an inflow point of the solvent 8th and the liquid level in the discharge section 6 training.

In 4 is a section of the heat pump 1 shown in one embodiment. In this embodiment, which is in the absorber 11 dissipated gas discharged. This embodiment is advantageous because the absolute pressure level in the absorber 11 lower than in the condenser 12 and thus preferably the gas in the absorber 11 collects. The illustrated section includes the absorber 11 , the suction device 3 , the pump 15 , a separator 40 , a collection container 41 and a connecting pipe 42 to the solution heat exchanger 18 , The solvent 8th , in this case the poor solution 23 from the absorber 11 , will, instead of according to 1 by means of the pump 15 to the solution heat exchanger 18 to be piped to the inflow outlet 9 the suction device 3 promoted. The intake section 5 the suction device 3 is with the absorber 11 connected to one another in the absorber 11 dissipate gas. The solvent 8th picks up the gas and goes over the drainage section 6 to a separator 40 directed. In the separator 40 the gas is released from the solvent 8th removed and the thus purified solvent 8th is used as an absorbent over the solution heat exchanger 18 the generator 12 fed. The discharged gas is stored in a collecting tank 41 if it is not allowed to be used in the environment, for example because it is toxic or explosive.

In this embodiment arises in the discharge section 6 a backpressure, which is described by the following formula: p _G = Δp _{pipe loss} + Δp _LWÜ + Δp _hydrostat + p _expeller . Here, p _{G is} the one in the absorber 11 prevailing pressure p of the _expeller in the expeller 12 prevailing pressure, Δp _{pipe loss,} a pressure drop due to pipe _losses , Δp _LWÜ a pressure that is needed to pass the absorbent through the solution heat exchanger 18 to drive and Δp _hydrostat due to a hydrostatic inlet height, which is the height between the suction device 3 and the inlet to the generator 12 corresponds, adjusting pressure due to the liquid column.

The at the intake section 5 applied pressure corresponds to that in the absorber 11 , Thus, the suction device must 3 be installed sufficiently high, so that the liquid column in the discharge section 6 can generate a sufficiently high hydrostatic pressure to the absorbent through the solution heat exchanger 18 , by pipe connections, against the hydrostatic inlet height in the expeller 12 and against that in the expeller 11 to promote prevailing pressure. This is depending on the design of the heat pump 1 feasible without difficulty.

As an alternative, as in 5 illustrates, in a further embodiment, only a partial flow from the expeller 12 flowing poor solution 22 branched off and as a solvent 8th the inflow section 9 be supplied. The solvent 8th this is done after the removal of the gas in the separator 40 freed from the gas and another connecting pipe 43 directed back to the absorber. This has the advantage that the back pressure is kept low. The back pressure below the intermediate section 7 is given by the following formula: p _G = Δp _{pipe loss} + Δp _hydrostat + p _expeller . This back pressure is much lower than that in the embodiment according to 4 , Optionally, in addition to a connection of the suction 5 with the absorber 11 also a connection with the capacitor 12 be provided so that gases from both components simultaneously by means of a suction 3 can be dissipated.

Should the gases from the condenser 12 are discharged, the embodiment is after 6 selected. This is the rich solution 23 from the condenser 12 as a solvent 8th for discharging the gas by means of the suction device 3 used. Similar to the embodiments of 4 and 5 are also a separator here 40 and a collection container 41 intended.

It is also possible to increase the efficiency of several suction devices 3 at different sections of the heat pump 1 provided. These suction devices 3 can then use solvent 8th operated from a single source or from several different sources the.

7 Graphically illustrates the effect that the discharge of the gas to that of the heat pump 1 achieved performance. In this case, the one from the absorber 11 to the solution heat exchanger 18 flowing rich solution 22 as a solvent 8th used. The from the absorber 11 leaking rich solution 22 is located in the absorber 11 prevailing pressure in the thermodynamic equilibrium or is slightly undercooled. A hermetic pump serves as a pump 15 to promote the rich solution 22 in the expeller 12 , In the present case, the performance of a freshly evacuated heat pump 1 be achieved.

In 7 four heat exchanger performance of an absorption refrigeration system are shown, and the efficiency, referred to here as COP. For two volume flows of the solvent through the suction device 3 It is shown how, after the deliberate supply of foreign gases into the absorption refrigeration system, at 14:40 and 16:54, the system performance and the efficiency are reduced, and after successful evacuation by means of the suction device 3 come back to their optimal level of performance.

The diagram 70 underlying embodiment of the heat pump 1 has a free fall height of 20cm. That is, the solvent 8th can in the discharge section 6 a distance of 20cm freefallend, so only guided by gravity, cover. A drop of at least 5cm has proven to be advantageous. Further, the solvent has 8th in the inflow section 9 a flow rate of between 260 and 330 liters per hour (l / h). Such a volume flow corresponds to volume flows for which conventional heat pumps 1 are designed. The suction device 3 has a tube diameter of 16 mm. Preliminary studies have found that at flow rates of 20 to 40 cm / s using water as the solvent 8th , an effective removal of gases can be achieved. This is also the case when using a water-lithium bromide solution.

The in the foregoing description, claims and drawings Features of the invention can both individually and in any combination for the realization of the invention in its various embodiments of importance be.

Claims (16)

Method for removing a gas from a heat pump ( 1 ), wherein in a pipeline system an inflow section ( 9 ), an angled outflow section ( 6 ) and a suction section ( 5 ) are formed, which with the inflow section ( 9 ) and the discharge section ( 6 ), wherein in the process a solvent ( 8th ) with the formation of contraction vortices from the inflow section ( 9 ) into the discharge section ( 6 ), the gas to be removed as a result of the contraction vortex from the solvent ( 8th ) and after flowing through the drainage section ( 6 ) is discharged from the piping system. Process according to Claim 1, characterized in that the solvent ( 8th ) in the discharge section ( 6 ) is moved by gravity driven. Process according to Claim 1 or 2, characterized in that the solvent ( 8th ) from the discharge section ( 6 ) is pumped. Method according to one of the preceding claims, characterized in that a flow velocity in the inflow section ( 9 ) and thereby a discharge rate for the removal of the gas from the heat pump ( 1 ) is controlled. Process according to one of the preceding claims, characterized in that as solvent ( 8th ) Water is used. Process according to one of the preceding claims, characterized in that the solvent ( 8th ) is discharged together with the gas to be discharged from the piping system. Method according to one of claims 1 to 4, characterized in that as solvent ( 8th ) a working fluid of the heat pump ( 1 ) is used. Method according to one of the preceding claims, characterized in that the solvent ( 8th ) absorbed gas by means of a separator ( 40 ) from the solvent ( 8th ) Will get removed. Process according to claim 8, characterized in that the gas removed from the solvent is stored in a collecting container ( 41 ) is collected. Heat pump ( 1 ) with a pipeline system in which a suction device ( 3 ) is formed for discharging a gas, characterized in that the suction device ( 3 ) an inflow section ( 9 ), a thereto angled outflow section ( 6 ) and a suction section ( 5 ), which communicates with the inflow section ( 9 ) and the discharge section ( 6 ), so that a solvent ( 8th ) with the formation of contraction vortices from the inflow section ( 9 ) into the discharge section ( 6 ), with which the gas to be removed from the solvent ( 8th ) and through the discharge section ( 6 ) can be dissipated. Heat pump ( 1 ) according to claim 10, characterized in that the inflow section ( 9 ) substantially at right angles to the discharge section ( 6 ) is arranged. Heat pump ( 1 ) according to claim 10 or claim 11, characterized by a pump connected to the discharge section for pumping off the solvent ( 8th ). Heat pump ( 1 ) according to one of claims 10 to 12, characterized by a with the inflow section ( 9 ), whereby as solvent ( 8th ) a working fluid of the heat pump ( 1 ) is usable. Heat pump ( 1 ) according to one of claims 10 to 13, characterized by a separator ( 40 ) for separating the gas from the solvent ( 8th ). Heat pump ( 1 ) according to claim 14, characterized by a connecting tube ( 42 . 43 ) for recycling a solvent ( 8th ) used working fluid of the heat pump ( 1 ). Heat pump ( 1 ) according to claim 14 or claim 15, characterized by a collecting container ( 41 ) for collecting from the solvent ( 8th ) separated gas.