DE2752005A1 - PROCEDURE FOR COOLING LIQUID IN A CLOSED CONTAINER AND DEVICE FOR CARRYING OUT THE PROCEDURE - Google Patents

Description

The invention relates to a method for cooling liquid in a closed container and also relates to a device for carrying out the Procedure. The invention can be used in particular for cooling lubricating fluid in machines, in particular for cooling the oil bath in hermetically sealed compressors in refrigeration systems, for example hermetically sealed compressors symmetrical cooling circuit.

809822/0733

7265/05 / Ch / Fr - 4 - November 21, 1977

The method according to the invention consists essentially in that to ensure the thermal Self-regulation of a liquid bath, which Energy loss in a closed container is absorbed, a partial evaporation of a vaporizable one Liquid caused by heat exchange via a heat exchanger surface immersed in the liquid bath, whereby at least the entire amount absorbed by the liquid bath due to the heat of vaporization maximum power dissipation is transferable and absorbable, and wherein the vaporizable liquid in one direction by gravity in a closed circuit between this heat exchanger surface and a condenser for the vaporized liquid is circulated.

The device for carrying out the method consists essentially of a circuit of a vaporizable one Liquid, consisting of an evaporator immersed in the liquid bath, its heat exchanger The surface area is sufficient to produce a thermal in a state of partial evaporation of the liquid To transmit flux which is at least equivalent to the maximum power loss absorbed by the liquid bath, a condenser for the vaporized liquid, and a liquid line through which the Liquid passes from the condenser to the evaporator as a result of its gravity, with a one-way valve in this line is switched.

In a special application example, the liquid bath into which the evaporator is

809822/0733 " ⁵ "

7465 1 05 / Ch / Fr - 5 - November 21, 1977

dives to the lubricant bath of a machine, which is used to cool the machine while it is in operation, whereby lost energy is dissipated in thermal form. However, the invention is equally applicable to the cooling of other liquids, which are in a closed container, for example, the invention is applicable to the cooling of lubricating oil in a motor housing, a gear housing and other similar devices.

The invention enables cooling by means of a simple device, the operation of which is self-regulating depending on the thermal flow to be discharged, that is, in particular, depending on the operating state of the machine whose lubricant is to be cooled.

In the device according to the invention, it is also advantageous that the circuit for cooling the liquid bath, in particular for cooling the oil bath a hermetically sealed compressor is independent of the cooling circuit of a refrigeration system in which the Circuit of the evaporable liquid is used to cool the oil in the hermetically sealed compressor. It is also possible to choose a suitable vaporizable liquid depending on the application. Furthermore, it is possible that the prevailing pressure in the circuit of the vaporizable liquid can be kept much lower than in the other circuits of the System. Furthermore, the invention enables the avoidance of pressure losses in circuits, as they would otherwise to cool the compressors in a refrigeration system

809822/0733

7465/05 / Ch / Fr - 6 - November 21, 1977

be used. This increases the efficiency of the compressor and reduces the overall energy consumption .

For the proper functioning of the device according to the invention, it is necessary that in the closed Circulation of the vaporizable liquid always has an amount of liquid in equilibrium with its saturated Steam is in circulation, this amount must be sufficient to feed the evaporator and to absorb the thermal power dissipation, the filling must be sufficient so that a circulation caused by gravity can be maintained. These conditions are easy too realize by appropriate dimensioning of the closed circuit, in particular by appropriate Design of the evaporator surface and the condenser surface, the amount of liquid introduced into the closed circuit of the cooling behavior of the Condenser, depending on the permitted maximum temperature of the liquid bath to be cooled and in Dependence on the maximum heat energy to be dissipated. An appropriately dimensioned circuit regulates itself automatically depending on the thermal to be discharged Energy and thus depending on the operating status of the associated machine. When operating will the liquid cooled in the condenser is heated in the evaporator, whereby it partially evaporates and its vapor pressure increases accordingly as does the speed of circulation. The temperature of the to be cooled increases Liquid bath, then the thermal power to be dissipated also increases, so that more liquid

809822/0733 ' ⁷ "

7465/05 / Ch / Fr - 7 - November 21, 1977

Liquid is evaporated, the limits being set by the maximum thermal flow, which is determined by the exchanger surface of the evaporator.

No special materials are required for the device. The evaporator, which is immersed in the bath to be cooled, can consist of a coiled tubing with a round, oval or flattened pipe cross-section, possibly with ribs or consist of a surface exchanger or a tubular battery. The condenser is also of the usual type, cooling there by air or can be done by convection. The easiest way is to expose the condenser to the ambient air.

The vaporizable liquid is introduced into the closed circuit after it has been evacuated became. The liquid is introduced in such an amount that it is in equilibrium with the saturated vapor during each operating condition of the device.

Embodiments of the invention are given below explained in more detail with reference to the drawings. Show it:

Fig. 1 schematically shows a conventional cooling system

Design with a hermetically sealed compressor and a precondenser;

2 shows a cooling device according to the invention for cooling the oil of a compressor of a cooling system and

3 shows a shaft bearing, the oil of which is to be cooled.

809822/0733 - ₈ -

7465/05 / Ch / Fr - 8 - November 21, 1977

In Figs. 1 and 2, a cooling system is shown schematically, consisting of a refrigerator 1, and a cooling liquid circuit consisting of an evaporator 2 in the refrigerator 1, a compressor 3, a condenser k and a pressure reducing valve 5. The closed line circuit for the Cooling liquid runs from the evaporator 2 to the compressor 3, where the liquid evaporated in the evaporator is compressed, to the condenser ^ where the compressed liquid is condensed by heat exchange with the ambient air and to the pressure reducing valve 5, which is a capillary valve.

The compressor 3 is a hermetically sealed compressor with a symmetrical cooling circuit. That the Housing enclosing the compressor includes an oil bath 6, which is dependent on the operating state of the compressor absorbs its energy losses in the form of thermal energy.

In order to use the power absorbed by Bad 6 loss of energy to dissipate, is provided a cooler 7 in the known system of FIG. 1, which dips into the oil bath 6, and a exchangers θ, which is also pre-condenser is called and is exposed to the ambient air. The cooling liquid is the same as that used for the cooling system as a whole. The cooling device 7 and the precondenser θ are connected in series in the cooling liquid circuit between the compressor 3 and the condenser k.

809822/0733

7465/05 / Ch / Fr - 9 - 21 November 1977

In such a system, the coolant is promoted for the oil bath of the compressor by the compressor itself. This inevitably results in pressure losses in the cooling coils in the oil bath and in the pre-condenser, which reduce the efficiency of the compressor. These pressure losses correspond in the same way to an additional one Consumption of electrical energy and continue to increase the compression ratio by increasing the temperature at the end of the compression. Another disadvantage is can be seen in the fact that after the compressor has stopped, the oil bath does not cool down further, so that the oil bath remains warm while the compressor is stopped.

In the device according to the invention according to FIG. 2, however, the cooling of the oil bath 6 of the compressor is brought about by a closed circuit which is independent of the rest of the cooling circuit. The closed circuit contains a liquid in equilibrium with its saturated vapor. The liquid is in particular freon, which is introduced into the closed circuit after air has been removed from it.

The circuit according to the invention comprises an evaporator 11 in which the liquid partially evaporates by heat exchange with the oil bath to be cooled. The evaporator has coils that protrude into the oil bath, corresponding to the cooler 7 in FIG. 1. In order to be able to dissipate the transported heat, a condenser 12 is provided, where the evaporated liquid is condensed. The condenser is preferably made of finned tubular

809822/0735 " ¹⁰ "

7465/05 / Ch / Fr - 10 - 21 November 1977

snakes exposed to the ambient air. This condenser is arranged above the compressor 6 . As a result, a pipe branch 13 is formed, in which the steam rises which was previously evaporated in the evaporator 11 and which then condenses in the condenser 12. Furthermore, a descending pipeline 14 is formed through which the condensed liquid flows back to the evaporator 11 as a result of gravity. A component is arranged in this return line 14- which prevents a flow of liquid in the other direction. In the example shown, it is a pipe loop that forms a siphon. Of course, any other one-way valve can be used, such as a flap valve or a float valve.

In the example shown, the refrigeration compressor has a Power consumption of 200 W. The power transferred to the oil bath during operation is in the On the order of 40 to 50 W.

The liquid in the cooling circuit for the oil bath consists from Freon 113, a trifluorotrichloroethane. The amount of freon introduced into the circuit was 30 cm at ambient temperature and 1 bar pressure. The boiling temperature under these conditions was 47 C.

The inner surface of the coils of the evaporator 11, which are immersed in the oil bath, was 140 cm inner surface of the coils of condenser 12 was 2000 cm. The tube of the evaporator 11 had one Outside diameter of 6 mm and an inside diameter of

809822/0733 ' ^U "

27520Ü5

7465/05 / Ch / Fr - 11-21 November 1977

4 mm, while in the case of the condenser the pipe outer diameter 12 mm and the pipe inside diameter was 10 mm. The inner diameter of the pipe 13 was 8 mm and that of the pipe 14 x 6 mm. The hydraulic one-way connection 15 was at a height of 20 cm above the evaporator 11 arranged. During the operation of the cooling device, there was a stable circulation of the vaporizable Liquid in a closed circuit. In equilibrium, i.e. i.e., when the compressor is running, was fraudulent the temperature at the level of the evaporator 11 is about 60 to 70 °, which is a pressure of the saturated Freon vapor in the closed circuit of 2 to 3 bar. During the standstill of the compressor for a period of about 10 minutes, which normally corresponds to the interruption time in a refrigeration system the temperature at the level of the evaporator 11 is lowered to approximately 50.degree. In the event of prolonged interruptions in operation, the circulation of the vaporizable liquid continued and cooling down to ambient temperature took place, the pressure in the closed circuit falling to a value of the order of magnitude of 0.4 bar.

3 shows a further application for oil cooling. This figure shows a bearing 21 in which an oil cooler 22 is arranged, which consists of pipe coils immersed in an oil bath, and the part is a closed circuit, which i.a. has a condenser 23 which is exposed to the ambient air. This condenser is above the oil bath arranged and a line 24 · connects the cooler 22

- 12 -

809822/0733

7465/05 / Ch / Fr - 12-21 November 1977

with the condenser 23. In the return line between the condenser 23 and the cooler 22 a hydraulic shutter 25 is arranged, which causes that the condensed Cooling liquid can only flow in one direction under the force of gravity, that is to say back to the cooler 22 able.

809822/0733

Claims (1)

Rolf Charter Patent attorney
Augsburg 31 P.O. Box 242 ^R Teicftinfo82i / ^r 3tlow ⁸ Note: CENTER TECHNIQUE DES Posisrhcckkonio Munich NrI547W-8OI INDUSTRIES MECANIQUES 7 ^ 65/05 / Ch / Fr Augsburg, November 21, 1977 Expectations 1.) Method for cooling an in a closed Be ^ - ^ holder located liquid bath, characterized in that by means of partial evaporation of an evaporable liquid Exchange of goods via an exchange surface located in the bathroom at least the entire maximum from The power absorbed is transferred to the bath and absorbed by the heat of vaporization, and the evaporated Liquid in the circuit is fed to a condenser, from where the condensed liquid as a result Gravity reaches the exchanger surface. 2. The method according to claim 1, characterized in that at the maximum value of the heat output to be dissipated there is still so much unevaporated Liquid is in a closed circuit that its circulation is maintained due to gravity. 3. The method according to claim 1 or 2, characterized in that the lubricating oil bath one Machine is cooled down. 809822/0733 275200b 7465/05 / Ch / Fr - 2 - November 21, 1977 Ψ. Method according to claim 3, characterized in that the oil bath is a hermetic one sealed refrigeration system compressor is cooled. 5. Device for carrying out the method according to one of claims 1 to k, characterized in that the closed circuit of the vaporizable liquid comprises an evaporator immersed in the liquid bath, the exchanger surface of which allows a heat loss in the case of partial evaporation of the liquid, which is at least equal to the maximum im Bad power loss is present, a condenser for condensing the evaporated liquid and a return line through which the condensed liquid flows back to the evaporator due to its gravity, an organ being connected in this line which allows the liquid flow only in this direction. 6. Apparatus according to claim 5, characterized in that the evaporator in a lubricating bath immersed. 7. Apparatus according to claim 5, characterized in that the evaporator in the oil bath of a refrigeration system compressor is immersed. 8. Apparatus according to claim 7, characterized in that the condenser is exposed to the ambient air. 809822/0751 - 3.