DE1036282B - Cooling system - Google Patents

Description

Cooling system The invention relates to a cooling system with a Compressor for a refrigerant and a subsequent cooler for the refrigerant, furthermore with at least two behind the cooler, connected in series Expansion turbines, with a heat exchanger with the primary channel in front of each turbine is switched on, and consists in that the last expansion turbine escaping Refrigerant through the secondary channel at least the one in front of the first turbine Heat exchanger is passed. The system can be used especially for deep freezing use because the refrigerant, which has been expanded several times, is returned and at least in front of the first expansion turbine in heat exchange with the refrigerant to be expanded is brought.

A mine cooling system is known in which a first, designed as a turbine expansion machine a heat exchanger with its primary channel is switched, through whose secondary channel the one leaving the expansion turbine Cooling air is guided, which is thereupon by a further, designed as a compressed air motor Expansion machine and then to the workplace in the mine tunnel is led. The cooling air becomes a heat exchange, but not after the second expansion with the one that flows in front of the first expansion machine and is to be expanded for the first time Uses air, but enters the mine tunnel when it leaves the air motor the end. In a known mine air conditioning system modified in contrast to this, part of the cooling air flowing out of the second expansion machine is returned, however, in this known system, it is only used in one before the second expansion machine lying water separator in heat exchange with that of the second expansion machine brought cooling air supplied. This is in front of the first expansion machine Plant no heat exchanger at all, in which the second expansion machine outflowing cooling air with the cooling air flowing into the first expansion machine could be brought into heat exchange. For effective heat exchange is However, it is just necessary to remove the heat from the last expansion machine Medium to the medium to be expanded which is fed to the first expansion machine to be transferred, i.e. the refrigerant flowing out of the last expansion machine through the secondary duct of a heat exchanger located in front of the first expansion machine to lead, through the primary channel of which the first expansion machine is supplied Refrigerant flows.

In one embodiment of the invention, there are on the exit side of the last turbine, all heat exchangers located between the turbines connected with their secondary channel in series, the last of which is connected on its outlet side to the suction side of the compressor. This in refrigerant flowing through the primary channels of the heat exchanger, which is produced by expansion is then cooled by the one from the last turbine incoming, flowing back through the secondary channels of the heat exchanger to the compressor Refrigerant itself is further cooled. The low temperature of the last expansion stage escaping refrigerant can, for. B. via another, taking place in the circuit Heat exchange, in which the medium to be cooled is also involved, can be used.

In one embodiment of the last-mentioned type of the invention The heat exchangers contain tertiary ducts through which a medium to be cooled is directed. The medium to be cooled is also through the between the turbines switched heat exchanger out.

In one embodiment of the invention are turbines and intervening Heat exchangers are dimensioned so that the temperature gradient in the turbines is compared to the temperature gradient in the heat exchangers is small. The thermodynamic Losses are then kept low.

In a further construction of the invention, the heat exchangers are located - apart from the one switched on before the first expansion turbine - advantageous as a direct current heat exchanger, with their secondary channels in series in a line carrying a medium to be cooled or liquefied. Here is through the through Expansion achieved cold behind each turbine in each case the medium to be cooled is cooled; the refrigerant is heated in the process. Turbines and heat exchangers can be configured taking into account temperature, pressure and The size of the medium to be cooled should be dimensioned in such a way that all turbines operate on approximately the same Working temperature level.

In one embodiment of the invention is through the expansion turbines all refrigerant coming from the compressor and the cooler is routed. the The amount of refrigerant passed through the turbines in the unit of time then has d; ii largest possible amount. This has the consequence that llci given turbine dimensions also 4i ° 1> 2i of each expansion achieved enthalpy decrease l: 2 soild: rs is large and consequently the same as the quotient of the enthalpy decrease and the specific \\ 'poor Temperature decrease becomes sufficiently large even when a gaseous refrigerant of high specific heat is used. By an attachment of the last mentioned Design it is possible, for. B. Hydrogen with the high specific heat of 3.4 cal g-1 degree- 'at 0 ° C in an economical «ise as a refrigerant for one To use cooling process with expansion under work power in turbines.

The above-mentioned exemplary embodiment is also important insofar as when the amount of secondary refrigerant flowing through the turbines does not become small; that is, for some reason, the amount of refrigerant delivered by the compressor kept relatively low in the unit of time and - in contrast to the one in question Embodiment of the invention - only part of it through the expansion turbines cleverly, the turbines must be so small that difficulties arise would arise to produce them at all.

In one embodiment of the invention there are all identical turbines, so turbines with nothing but the same impellers and diffusers and finitely the same Dimensions of these parts used; this is> made possible because the in each Turbine volume increase due to expansion due to a decrease in temperature Volume decrease achieved in a subsequent heat exchanger is compensated for, so that in each turbine about the same volume flows in the unit of time. At low \ 'olumenalnveichungen the turbines can optionally except for a part, z. B. the diffuser, be designed the same, and the deviations in the throughput volume are only compensated by a different diffuser. So must For a given system, only one spare rotor can be kept in stock. aside from that If necessary, the rotors of the individual turbines can be exchanged for one another will.

The drawing shows exemplary embodiments.

Figures 1 through 3 are simplified circuit diagrams of three in accordance with the present invention trained cooling systems: Figs. 4 to 6 are associated working diagrams.

In a refrigerant circuit are a compressor, preferably an oil-free Laby-rinth piston compressor 1 z. B. with a gas-tight housing, a cooler, z. B. a water cooler 2, behind it the primary duct 3 of a first heat exchanger 4, further a first expansion turbine 5, the primary duct 6 of a second heat exchanger 7, then a second expansion turbine 8 identical to the turbine 5, a primary duct 9 of a third heat exchanger 10 and then a Third expansion turbine 11, which is identical to the turbines 5, 8: it is followed by the three secondary channels 13, 14, 15 of the heat exchangers 10, 7, 4 on the one hand and, parallel to this, the primary channel 16 of a further heat exchanger 17 on the other in a return branch 12. A line 19 leading the itlediuni to be cooled is passed through the secondary channel 18 of the heat exchanger 17. The turbines 5, 8 and 11 are connected in series, and the primary channel 6 of the heat exchanger 7 is connected between the turbines 5, 8 and the primary channel 9 of the heat exchanger 10 is connected between the turbines 8, 11. All of the refrigerant coming from the compressor i and the cooler 2 is passed through the turbines.

In a modified design, the heat exchangers 4, 7, 10 tertiary channels 38, 39, 40. through the one line connected to line 19 18 ', which is shown in dashed lines in Fig. 1 and the line 18 of the first Example corresponds. The parts 16 to 18 are omitted in this embodiment.

In the diagram according to FIG. 4 belonging to the first design according to FIG. 1, the entropy S is plotted on the abscissa and the temperature T is plotted on the ordinate. From point 20 (FIGS. 1 and 4) the gaseous refrigerant, which is compressed in the compressor 1 and cooled in the cooler 2, passes to point 21, and continues through isobaric cooling in parts 3, 4 to point 22, from where it enters the Turbine 5 enters, where it experiences an enthalpy and temperature decrease due to the external work performance during expansion and arrives at point 23, which is on an isobar of lower magnitude. Thereupon the refrigerant in parts 6, 7 is further withdrawn isobaric heat, and it arrives at point 24. After a further decrease in enthalpy or temperature due to expansion in turbine 8, the refrigerant reaches point 25 and after further cooling in parts 9, 10 Point 26. It then flows through the last turbine 11 and is guided to point 27 in the process. The refrigerant component flowing on via branch 12 is heated in duct 13 and reaches point 29. The heat absorbed comes from the refrigerant in duct 9. After flowing through duct 14, the refrigerant reaches point 31 with further heating in the exchanger 4 again to point 20 and again in the compressor 1.

The one flowing through branch 16 used for cooling in channel 18 Share of the refrigerant coming from the last turbine 11 is compared to the kept relatively small by Zw-, ig 12 flowing portion, so that the Temperature gradient in the turbines 5, 8, 11 compared to your temperature gradient in the heat exchangers 4, 7 and 10, both to the one in the primary channels 3, 6, 9 as well as that in the secondary channels 13 to 15 can be kept small. That the temperature gradient in the turbines 5, 8, il compared to that in the heat exchangers 4, 7, 9 is small, also results from your T-S diagram (Fig. 4).

In the system according to FIG. 2, the last turbine 11 is followed by another Heat exchanger 34, whose primary channel is denoted by 35 and whose secondary channel is denoted by 36 is. The refrigerant coming from channel 35 flows in via a single line 37 the heat exchanger 4 and through its secondary channel 15 back into the compressor 1. This is closed by the secondary channels 14, 13, 36 of the exchangers 7, 10, 34 cooling Medium directed. The arrangement can be made so that at the inputs 22, 24, 26 of all turbines is about the same temperature. In this case it can extract the heat from all the medium to be cooled at a practically constant temperature, how it z. B. is necessary when liquefying a gas.

As can be seen from the associated diagram according to FIG. will that Refrigerant in this example after the cooler 2 from point 21 through the parts 3, 4 to your point 22 ', which is much lower than point 22. The three Expansion sections (enthalpy or temperature, temperature decrease sections) 22-23, 24-25, 26-27 as well as the three isobaric heat absorption sections 23-24, 25-26 and 27-28 'lie in this example at about a constant temperature level.

In your embodiment according to FIG. 3, that is already divided Channel 9 of exchanger 10, refrigerant coming in at 26 'in two branches 42, 43. Branch 42 is via a further turbine 44, the primary channel 45 of a heat exchanger 46, a turbine 47, the primary duct 48 of a further heat exchanger 49 and a turbine 50 led to a point 51. Line 43, on the other hand, is through the Secondary channel 52 of exchanger 46, further via a throttle element 53, the secondary channel 54 of the exchanger 49, a throttle element 55, the secondary channel 56 of a heat exchanger 57 and via a throttle element 58 into a collecting container 59 for liquefied: medium solved. A line 60 is led from the container 59 to point 51; about you a portion of its contents in gaseous form ° eiltnoillin - il can be transferred to the container 59. The extraction line 60 leads behind point 51, through the primary channel 62 of the exchanger 57, and joins at 64 with a line passing through the heat exchanger 17 65 to divide again at 66 into the two branches 12, 16, which correspond accordingly the example of FIG. 1, the exchanger 10, 7, 4 on the one hand and the exchanger 17 prevail on the other hand and then after reunification in the compressor 1 lead back. So much medium is constantly fed to the system via line 65, how the product is removed from the container 59 via a valve 68.

In your example according to FIG. 3 - in contrast to the embodiments according to Fig. 1 and 2 - the medium to be cooled at the same time also refrigerant in the turbines and the associated heat exchangers. In that at 26 'in the turbine branch 42 and the throttle branch 43 is divided, it is achieved that the liquid to be liquefied The amount of gas in branch 43 is only further cooled and liquefied by means of heat exchange is, while the amount of gas in branch 42 due to work expansion, without to liquefy, cools further, so that it is capable of that which has been separated from it Amount of gas in branch 43 remove heat ztt. Partial condensation of the gas in the turbines 44, 47, 50 as a result of _1 #, cooling through expansion is avoided, thus the efficiency because of the possible partial condensation smaller throughput volumes for the. Turbines 44, 47, 50 does not go down.

According to the associated diagram (FIG. 6), at d ° m again on the abscissa is the entropy, on the ordinate the temperature is plotted and at which the in the parts 1 to 10, 13 to 15 ongoing sub-process is omitted the gaseous medium flowing through branch 42 with a decrease in its enthalpy or temperature from point 26 'via turbine 44 to point 70, then below Heat absorption in channel 45 of exchanger 46 isobaric to point 71 and further above Turbine 47 to 72 and via heat exchanger 49 to point 73 and finally via Turbine 50 passed to point 51. The medium passed through branch 43 is in Channel 52 partially liquefied and comes to point via liquefaction line 75 76; further it is in the throttle member 53 while keeping the enthalpy (isenthalp) constant relaxes and arrives at point 77, which is on an isobar of lower magnitude lies as point 76. The partially liquefied medium then passes through channel 54, further parts are liquefied. It gets to point 78. After again throttled relaxation in organ 55, through which it comes to point 79, permeated the medium channel 56, in which the remaining parts are liquefied, and the liquid is cooled. It reaches point 80 and from there after throttling in organ 58 to point 81 (container 59). The gaseous portion produced during throttling (Point 81 ') is transferred from point 81' to point 51 and from there together with the medium coming from branch 42 and the medium newly fed in via line 65 through exchangers 10, 7, 4 (channels 13, 14, 15) and 17 (channel 16) to the compressor 1 supplied.

Through the channel 18 of the exchanger 17, the newly supplied 11edium cleaned before it enters the actual cycle at 64, namely it will z. B. by condensation or by freezing out of undesired foreign matter freed.

The heat exchangers shown in the drawing can be completely be of any type, such. B. without or finite heat transfer medium; the exchangers are shown schematically in the drawing for the sake of simplicity.

Claims (10)

PATENT CLAIMS: 1. Cooling system with a compressor for a refrigerant and a subsequent cooler for the refrigerant, furthermore with at least two downstream of the cooler, expansion turbines connected in series, wherein A heat exchanger with the primary channel is switched on in front of each turbine, thereby characterized in that the last expansion turbine escaping refrigerant through the secondary channel of at least the heat exchanger located in front of the first turbine is directed. 2. Plant according to claim 1, characterized in that on the outlet side of the last turbine, all heat exchangers located between the turbines connected in series with their secondary channel, the last of which all of its outlet side is connected to the suction side of the compressor. 3. Plant according to claims 1 and 2, characterized in that the heat exchangers have tertiary channels contained, through which a medium to be cooled is passed. 4. Plant after Claims 1 and 2, characterized in that parallel to the secondary channels the heat exchanger is another heat exchanger, through the primary side Refrigerant also coming from the turbines and refrigerant to be cooled on the secondary side Medium is guided. 5. Plant according to claim 1, characterized in that that turbines and heat exchangers are dimensioned so that the temperature gradient in the turbines compared to the temperature gradient in the heat exchangers is. 6. Plant according to claim 1, characterized in that the heat exchanger - apart from the one switched on before the first expansion turbine - with their Secondary channels connected in series in one to be cooled or liquefied Medium leading line lie. 7. Plant according to claims 1 to 6, characterized characterized in that turbines and heat exchangers are dimensioned so that the temperature of the refrigerant is the same at the inlet of at least two turbines. B. system according to claim 1, characterized in that all refrigerant coming from the compressor and the cooler is routed. 9. Plant according to claim 1, characterized in that identical turbines are used. 10. Plant according to claim 1, characterized in that the turbines apart from the diffusers, are the same. Publications considered: German Patent No. 554464; Journal of the Association of German Engineers, 83 (1939), No. 36, p. 1027, Fig. 4 with associated description.