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(11) | EP 1 025 404 B1 |
| (12) | EUROPEAN PATENT SPECIFICATION |
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METHOD FOR SUPPLYING MAKE-UP WATER AND REFRIGERATION SYSTEM CARRYING OUT THE METHOD ZUFUHRVERFAHREN FÜR ZUSATZWASSER UND KÄLTEANLAGE ZUR DURCHFÜHRUNG DES VERFAHRENS FOURNITURE D'EAU D'APPOINT DANS LA RESERVOIR DE RECEPTION D'UN CONDENSEUR OU D'UN REFROIDISSEUR ATMOSPHERIQUE A EVAPORATION A PARTIR D'UNE SOURCE |
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| Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention). |
[0001] The present invention relates to a method for operating a refrigeration system by means of a refrigerant circuit, in which to condensate the refrigerant in said circuit a cooling water circuit is used, incorporating an evaporative condenser, evaporation losses from said condenser being topped up with the aid of make-up water being supplied to the condenser via a heat exchanger with the aid of which the liquid refrigerant of the refrigeration circuit is subcooled.
[0002] Currently, modern industrial cooling plants are generally equipped with evaporative condensers or with a combination of cooling towers and water-cooled condensers, for the purpose of dissipating the heat of condensation. In cooling systems of this nature, the cooling circuit normally incorporates a liquid vessel from which refrigerant is supplied to an evaporator. In the latter, the refrigerant evaporates and extracts the heat from the surrounding environment. The evaporated refrigerant is then supplied, by means of a compressor, to an evaporative condenser in which the refrigerant is condensed. Finally, the refrigerant is fed back to the liquid vessel. As has been stated, the evaporative condenser may also comprise a combination of a cooling tower and a water-cooled condenser.
[0003] A method in accordance with the type described in the preamble is known from Swiss Patent 392,576. According to this known method, cooling is carried out using a refrigerant which flows into a closed cooling circuit which includes an expansion device and a compressor and a heat exchanger. Cooling water which is heated in the heat exchanger and gives off the heat to an evaporative condenser also flows through the heat exchanger.
[0004] In order to maintain the water level in the evaporative condenser used, make-up water is metered more or less continuously into the receptacle tank of the condenser. The make-up water is brought into the water circulation circuit via a recirculation pump.
[0005] The make-up water is generally fed in at a temperature of from 10 to 15°C (springwater or tap water). This temperature is lower than the temperature of the water in the water receptacle tank. Since the mass ratio between the make-up water and the circuit water is generally at least 1:50, the relatively low temperature of the make-up water has scarcely any perceptible influence on the thermodynamic performance of the condenser. The fact that the make-up water is relatively cold is utilized according to the abovementioned Swiss patent by the fact that the make-up water is supplied from a source to the receptacle tank of the evaporative condenser via a heat exchanger in which the refrigerant, which flows in the cooling circuit from the liquid vessel to the evaporator, is cooled by the make-up water, which in this process is heated up.
[0006] The known method utilizes the relatively cold make-up water in the high-grade section of a cooling circuit. The actual heat exchange which takes place between the relatively cold make-up water and the refrigerant in the cooling circuit is not measured.
[0007] The object of the present invention is to provide a method in which the heat exchange which takes place between the relatively cold make-up water and the refrigerant can be used to gain more information about the performance and efficiency of the cooling system.
[0008] This object is achieved in the present invention by the fact that the method comprises the following steps:
- measuring the volume of make-up water supplied to the receptacle tank of the evaporative condenser and/or the cooling tower,
- measuring the temperature difference in the make-up water before it is used to cool the refrigerant and after it has been used to cool the refrigerant,
- calculating the amount of heat which has been supplied to the water,
- measuring the difference in temperature of the refrigerant before it is cooled with make-up water and after it has been cooled with make-up water,
- determining the refrigerant mass flow on the basis of the calculated amount of heat supplied to the water and the measured temperature difference in the refrigerant,
- measuring the suction pressure (Po) and the condenser pressure (Pc), respectively, of the refrigerant,
- using the measured values for the suction pressure (Po) and the condenser pressure (Pc) and the refrigerant mass flow to determine the instantaneous cooling capacity (Qo),
- and displaying this instantaneous cooling capacity (Qo) as required.
[0009] In this case, it is advantageous that the make-up water from the source is fed to the condenser via the heat exchanger.
[0010] Therefore, using the method according to the present invention, the cooling capacity Qo can be calculated using a flow meter for the make-up water and by measuring the temperatures of the make-up water. Both the flow measurement of the make-up water and the temperature measurements can be carried out with a very high level of accuracy. This also means that the instantaneous cooling capacity Qo can be calculated very accurately. In devices according to the prior art, the cooling capacity has to be calculated on the basis of a measurement of the flow of refrigerant which flows from the liquid vessel to the evaporator. The fact that a meter has to be placed in this line means an additional restriction in this line. Moreover, it may be that refrigerant flows through this line not only in the liquid phase but also in the gas phase. Therefore, in practice, accurate measurement of this flow of refrigerant is difficult to carry out accurately. Therefore, the measures according to the present invention replace the complex, expensive and inaccurate measurement of the refrigerant flow with an accurate measurement, which is easy to carry out, of the make-up water flow and the temperature change of the make-up water and the refrigerant.
[0011] Furthermore, it is possible according to the invention for the method to comprise the following steps:
- measuring the electric power (Pe) consumed for the purpose of operating the compressor(s) from the cooling system,
- calculating the instantaneous performance (COP, Coëfficient Of Performance) of the cooling system by dividing the calculated instantaneous cooling capacity (Qo) by the value measured for the electric power (Pe) consumed,
- displaying this instantaneous performance (COP, Coëfficient Of Performance) as required.
[0012] Moreover, according to the present invention it is possible for this method to comprise the following steps:
- calculating the instantaneous performance (COP) of the cooling system,
- changing process variables of the cooling system or the configuration of the cooling system,
- recalculating the instantaneous performance (COP) of the cooling system,
- repeating the above method steps as required.
[0013] This makes it possible to adjust and regulate the plant iteratively. This is because the corresponding COP can be calculated after each change in the process variables or the configuration. If this COP is more favourable than the COP before the changes were carried out, the new configuration or the new process variables can be maintained. If the COP measured is less favourable, it is possible to return to the previous setting. These method steps can be repeated until an optimum COP is reached.
[0014] By calculating the COP, it is also possible to monitor the performance of the cooling system. If a specific COP is expected and the calculated COP differs considerably from this, a user is able to look for possible faults.
[0015] Furthermore, it is possible, with the aid of the present invention, for the method to comprise the following steps:
- determining a maximum desired thickening factor for the water in the receptacle tank,
- using the value for Po, Pc and the refrigerant weight to determine the load of the condenser (Qc),
- determining the correct volume of make-up water on the basis of the calculated load of the condenser (Qc) and the predetermined thickening factor,
- and adjusting the volume of make-up water which flows to the receptacle tank per unit time as required.
[0016] The major advantage of this method is that it optimizes the water consumption. In cooling installations according to the prior art, it is generally the case that a flow of make-up water is continuously supplied to the receptacle tank of the evaporative condenser irrespective of the volume of make-up water which is actually required. In order to limit to a sufficient extent the maximum permissible increase in the quantity of salts in the water in the water receptacle tank (the so-called thickening factor), therefore, a continuous volume of waste water also flows from the receptacle tank to the sewer. By using the method according to the present invention as mentioned above, only the required volume of make-up water, which is adapted to the instantaneous performance of the cooling plant, is supplied to the water receptacle tank. As a result, excess and unnecessary water consumption is avoided.
[0017] Moreover, it is possible for the refrigerant to be injected from the liquid vessel to the said heat exchanger in a modulating manner.
[0018] This is because the make-up water is fed to the water receptacle tank virtually continuously. If the refrigerant is then introduced from the liquid vessel into the cooling circuit via a line which is alternately open and closed, no refrigerant flows through the heat exchanger when the line is closed, and at those moments the possible cooling potential of the make-up water supplied is still lost.
[0019] The present invention moreover relates to a cooling system intended to carry out the method according to the present invention.
[0020] The present invention is explained further with reference to the appended drawings, in which:
Figure 1 shows an overview of an industrial cooling plant according to the prior art.
Figure 2 shows a diagrammatic overview of a cooling plant according to the present invention.
Figure 3 shows the log P-H diagram of a possible cooling system according to the present invention in which NH3 is used as the refrigerant.
[0021] Figure 1 diagrammatically depicts a cooling plant 1 which is much used in the prior art. This cooling system comprises a cooling medium circuit including a liquid vessel 2, an evaporator 3 and a screw-type compressor 4 and an oil cooler 5. The refrigerant is supplied to an evaporative condenser 6 with the aid of a screw-type compressor. This evaporative condenser is fed with the aid of water from a water receptacle tank 7. In order to maintain the water level in this water receptacle tank 7, make-up water is supplied, with the aid of a line 8, from a source (not shown).
[0022] In the evaporative condenser, there is generally a certain level of subcooling of the liquid refrigerant. As a result, this liquid flows into the liquid vessel of the cooling liquid at a few degrees below the condensation temperature.
[0023] In most modem cooling plants, the compression step in the refrigerant circuit is carried out by means of screw-type compressors. These are cooled with the aid of oil coolers to which liquid refrigerant is regularly supplied from the liquid vessel using a thermosyphon system. Part of the refrigerant will evaporate as a result of heat exchange with the oil coolers. The heated refrigerant is then returned to the liquid vessel.
[0024] Figure 2 shows a cooling system 20 according to the present invention. In addition to the components which have already been discussed in Figure 1, the cooling device 20 comprises a heat exchanger 21. The heat exchanger 21 is connected, on the one hand, to the feed line for springwater or tap water 22 and is connected, on the other hand, to the outlet line 23 from the liquid vessel 2. In the heat exchanger 21, the refrigerant will be cooled by the relatively cold make-up water before it is delivered to the evaporator 3. As a result of this measure, the cooling capacity of the cooling system 20 will increase.
[0025] The relatively cold make-up water is used in the relatively "high-grade" section of the cooling circuit. This is because when a refrigerant is injected from the liquid vessel 2 into the evaporator 3, the pressure of the refrigerant will fall from the relatively high condenser pressure to the lower evaporator pressure. As a result, part of the refrigerant evaporates before it can contribute to the actual cooling process. That part of the refrigerant which evaporates in this phase is also known as the flash vapour. By now using the make-up water to cool the refrigerant which is flowing from the liquid vessel 2 to the evaporator, the amount of flash vapour will be reduced, so that the cooling potential of the refrigerant increases without employing additional energy other than the cooling potential of the make-up water.
[0026] The contribution of the relatively cold make-up water in the section of the cooling process between the liquid vessel and the evaporator is much higher than if the make-up water were to be supplied directly to the water receptacle tank 7 of the condenser. This results from the fact that the mass ratio of the make-up water and the circulation water, which is generally at least 1:50, means that the relatively cold make-up water will have scarcely any perceptible influence on the thermodynamic performance of the condenser 6.
[0027] Moreover, it is possible for the refrigerant to be injected from the liquid vessel to the said heat exchanger in a modulating manner.
[0028] This is because the make-up water is fed to the water receptacle tank virtually continuously. If the refrigerant is then introduced from the liquid vessel into the cooling circuit via a line which is alternately open and closed, no refrigerant flows through the heat exchanger when the line is closed, and at those moments the possible cooling capacity of the make-up water supplied is still lost.
[0029] It can be seen in Figure 2 that the cooling system 20 is equipped with two compressors. It is clear that the system may also comprise more compressors. Each of the compressors is provided with a measuring element 24, with the aid of which the electric power consumed by the compressors can be measured. The evaporative condenser 6 is also provided with a measuring element 25, in order to be able to measure the electric power consumed by the fan of the evaporative condenser 6.
[0030] Using the method according to the present invention, it is possible to measure the volume of make-up water which is supplied to the water receptacle tank 7 through the line 8. Moreover, the temperature of the make-up water is measured before the make-up water in the line 8 flows into the heat exchanger and after the make-up water has flowed out of the heat exchanger 21. These temperature measurements, as well as the flow measurement of the make-up water, together provide the total amount of heat supplied to the water. Moreover, in the line 23 it is possible to measure the difference in temperature of the refrigerant before the refrigerant in the line 23 is cooled by the make-up water and after it has been cooled with the make-up water. The refrigerant mass flow can be determined on the basis of these measurements and the calculated amount of heat supplied to the water.
[0031] Then, the suction pressure Po and the condenser pressure Pc in the cooling system are respectively measured. The instantaneous cooling capacity Qo can be determined using the measured value for the suction pressure Po and the condenser pressure Pc and the refrigerant mass flow determined. This therefore means that a cooling capacity of the cooling system 20 is known at all times. This instantaneous cooling capacity Qo can be displayed as required, for example on a control panel.
[0032] By additionally measuring the electric power Pe consumed which is required to operate the cooling system 20, it is moreover possible to determine the instantaneous performance, i.e. the COP, of the cooling plant. This COP is defined by dividing the instantaneous cooling capacity Qo by the value for the electric power Pe consumed. This instantaneous performance, i.e. the COP, can also be displayed as required.
[0033] In practice, having the instantaneous COP at the disposal of the operators is an important instrument for optimal control of the cooling system 20. It is possible, for example, to change the process variables of the cooling system. This can be achieved, for example, by switching one of the compressors 4 used in the cooling system 20 from full load to a part load. After these new process variables have been set, the COP of the cooling system can be determined again. Depending on the calculated value, it is possible to establish whether the COP has risen or fallen. If the COP has in fact risen, other process variables can then be changed. It is also possible, for example, to change the configuration by switching off one or more compressors. Process variables and/or the configuration of the cooling system can be varied until it is found that a higher COP can no longer be achieved. In other words, the present nvention makes it possible to carry out iterative control until an optimum COP is reached.
[0034] The present invention can also be used to optimize the supply of make-up water to the evaporative condenser. This is achieved as follows:
on the basis of a one-off hardness measurement of the make-up water, a desired thickening factor is determined, for example 2. The desired thickening factor is the maximum permissible increase in the quantity of salts in the water which is situated in the water receptacle tank.
[0035] During use of the system 20, the volume of water in the water receptacle tank 7 is measured continuously. Moreover, the difference in temperature of the water which flows via the feed line 22 to the heat exchanger 21 is measured before this water reaches the heat exchanger and after the water has flowed out of the heat exchanger 21.
[0036] The amount of heat supplied to the water is calculated on the basis of this temperature measurement.
[0037] Then, the temperature difference in the refrigerant before it flows into the heat exchanger and after it has flowed out of the heat exchanger is measured. The refrigerant mass flow is determined using the calculated amount of heat which is supplied to the water in the heat exchanger 21.
[0038] Then, the suction pressure Po and the condenser pressure Pc of the refrigerant are respectively measured.
[0039] Using the values for Po, Pc and the refrigerant mass flow, the instantaneous cooling capacity Qo and the load of the condenser Qc are respectively determined.
[0040] Then, the correct volume of make-up water is determined on the basis of the Qc calculated and the predetermined thickening factor.
[0041] If there is any reason to do so, the volume of make-up water to be supplied which flows to the receptacle tank per unit time is adjusted on the basis of the calculated volume of make-up water.
[0042] The abovementioned actions may, of course, take place continuously, with the result that the correct volume of water is constantly adjusted and the liquid optimally subcooled.
[0043] In order to explain the operation and advantage of the present cooling system, the following calculation example is given with reference to Figure 3: Assume that the cooling system 20 according to the present invention operates with NH3, with the following parameters:
Qo = 1000 kW
to = -10°C (evaporative temperature)
tc = +35°C (condensation temperature).
[0044] The appropriate cooling circuit is illustrated in the log P-H diagram as represented in Figure 3.
[0046] According to the "rule of thumb" that approximately 3 kg of make-up water is consumed per kWh of condenser heat to be dissipated (thickening factor ≈ 2), it follows that the make-up water consumption is 1212 × 3 = 3636 kg/h.
[0047] Suppose that the make-up water is heated from 12°C to 32°C, then it is possible to dissipate
subcooling heat, i.e., per kg of circulating refrigerant,
= 92 kJ, i.e. the refrigerant is subcooled to 15°C.
[0048] The cooling capacity Qo increases from 1000 kW to (1000 + 84.8) = 1084.8 kW. This means that the cooling capacity increases by a good 8% without using additional energy apart from the cooling potential of the make-up water.
[0049] Another possible advantageous application is in water-cooled cooling systems for air-conditioning purposes. These systems are generally combined with cooling towers. By positioning a liquid subcooler between the condenser and the evaporator upstream of the injection component (thermostatic expansion valve, high-pressure float or throttling port), it is possible to achieve the same resultant as that described above and in practice to achieve increases in capacity of from 8 to 10%. Naturally, the control would have to take place in the same way as that described above.
1. Method for operating a refrigeration system by means of a refrigerant circuit, in
which to condensate the refrigerant in said circuit a cooling water circuit is used,
incorporating an evaporative condenser, evaporation losses from said condenser being
topped up with the aid of make-up water being supplied to the condenser via a heat
exchanger with the aid of which the liquid refrigerant of the refrigeration circuit
is subcooled, characterized in that the method comprises the following steps:
- measuring the mass flow of water supplied through the heat exchanger,
- measuring the temperature difference in the make-up water before it is used to cool the refrigerant and after it has been used to cool the refrigerant,
- calculating the amount of heat which has been supplied to the water,
- measuring the difference in temperature of the refrigerant before it is cooled with make-up water and after it has been cooled with make-up water,
- determining the refrigerant mass flow on the basis of the calculated amount of heat supplied to the water and the measured temperature difference in the refrigerant,
- measuring the suction pressure (Po) and the condenser pressure (Pc), respectively, of the refrigerant,
- using the measured values for the suction pressure (Po) and the condenser pressure (Pc) and the refrigerant mass flow to determine the instantaneous cooling capacity (Qo),
- and displaying this instantaneous cooling capacity (Qo) as required.
2. Method according to Claim 1, characterized in that the method comprises the following steps:
- measuring the electric power (Pe) consumed for the purpose of operating the cooling system,
- calculating the instantaneous performance (COP) of the cooling system by dividing the calculated instantaneous cooling capacity (Qo) by the value measured for the electric power (Pe) consumed,
- displaying this instantaneous performance (COP) as required.
3. Method according to Claim I or 2, characterized in that the method comprises the following steps:
- calculating the instantaneous performance (COP) of the cooling system,
- changing process variables of the cooling system or the configuration of the cooling system,
- recalculating the instantaneous performance (COP) of the cooling system,
- repeating the above method steps as required.
4. Method according to one of the preceding claims, characterized in that this method comprises the following steps:
- determining a maximum desired thickening factor for the water in the receptacle tank,
- using the value for Po, Pc and the refrigerant mass flow to determine the load of the condenser (Qc),
- determining the correct volume of make-up water on the basis of the calculated load of the condenser (Qc) and the predetermined thickening factor,
- and adjusting the volume of make-up water which flows to the receptacle tank per unit time as required.
5. Method according to one of the preceding claims, characterized in that the refrigerant is injected from a liquid vessel wherein the refrigerant is injected
from the liquid vessel to the heat exchanger in a modulating manner.
6. Cooling system (20) for carrying out the method according to one of the preceding
claims, comprising a refrigerant circuit, incorporating a liquid vessel (2) for refrigerant
by means of an outlet line (23) connected to an evaporator (3), the evaporator (3)
being connected to a compressor (4), the compressor being connected to a condensor
(6), wherein the condensor is connected to the liquid vessel (2), the condensor being
an evaporative condensor (6), equipped with a water receptacle tank (7), which is
connected to a feed line (22), for supplying make-up water to the water receptacle
tank (7), wherein this system comprises a heat exchanger (21), which is connected
both to the feed line (22) for the receptacle tank (7), and to the outlet line (23)
from the liquid vessel (2), characterised in that the system comprises means for measuring the mass flow of water supplied through
the heat exchanger (21), means for measuring the temperature of the water in the feed
line upstream and downstream over the heat exchanger (21), means for calculating the
amount of heat which has been supplied to the water in the heat exchanger (21), means
for measuring the temperature of the refrigerant in the outlet line (23) upstream
and downstream of the heat exchanger (21), means for determining the refrigerant mass
flow on the basis of the calculated amount of heat supply to the water in the heat
exchanger (23) and the measured temperature difference of the refrigerant in the heat
exchanger (21), means for measuring the suction pressure (Po) and for measuring the
condensor pressure (Pc) of the refrigerant, and means for determining the instantaneous
cooling capacity (Qo) using the measured values for the suction pressure (Po) and
the condensor pressure (Pc).
7. Cooling system (20) according to claim 6, characterised in that the cooling system is equipped with means for displaying the instantaneous cooling
capacity (Qo).
8. Cooling system (20) according to claim 6 or 7, characterised in that the system comprises means (24, 25) for measuring the electric power (Pe) consumed
for the purpose of operating the cooling system, means for calculating the instantaneous
performance (COP) of the cooling system (20) by dividing the calculated instantaneous
cooling capacity (Qo) by the value measured for the electric power (Pe) consumed.
9. Cooling system (20) according to claims 6-8, characterised in that the cooling system (20) comprises means for displaying the instantaneous performance
(COP).
10. Cooling system (20) according to claims 6-9, characterised in that the system (20) comprises means for determining a maximum desired thickening factor
for the water in the receptacle tank, means for determining the load of the condensor
(Qc), using the value for Po, Pc and the refrigerant mass flow, means for determining
the correct volume of make-up water on the basis of the calculated load of the condensor
(Qc) and the predetermined thickening factor, and means for adjusting the volume of
make-up water which flows to the receptacle tank (7) per unit time.
11. Cooling system (20) according to claims 6-10, characterised in that the system (20) comprises means for injecting refrigerant to the heat exchanger (21)
from the liquid vessel (2) in a modulating manner.
1. Verfahren zum Betreiben einer Kälteanlage mittels eines Kühlmittelkreislaufes, wobei
zum Kondensieren des Kühlmittels in dem Kreislauf ein Kühlwasserkreislauf verwendet
wird, der einen Verdampfungskondensator beinhaltet, wobei Verdampfungsverluste des
Kondensators mit Hilfe von Zusatzwasser ausgeglichen werden, das dem Kondensator über
einen Wärmetauscher zugeführt wird, mit dessen Hilfe das flüssige Kühlmittel des Kühlmittelkreislaufs
unterkühlt wird, dadurch gekennzeichnet, daß das Verfahren die folgenden Schritte aufweist:
- Messen des Massenflusses des durch den Wärmetauscher zugeführten Wassers,
- Messen der Temperaturdifferenz im Zusatzwasser, bevor es dazu verwendet wird, das Kühlmittel zu kühlen, und nachdem es dazu verwendet wurde, das Kühlmittel zu kühlen,
- Errechnen der Wärmemenge, die dem Wasser zugeführt wurde,
- Messen der Temperaturdifferenz des Kühlmittels, bevor es mit Zusatzwasser gekühlt wird und nachdem es mit Zusatzwasser gekühlt wurde,
- Bestimmen des Kältemittelmassenflusses auf der Basis der errechneten Wärmemenge, die dem Wasser zugeführt wurde, und der gemessenen Temperaturdifferenz im Kühlmittel,
- Messen des Saugdruckes (Po) bzw. des Kondensatordruckes (Pc) des Kühlmittels,
- Verwenden der gemessenen Werte für den Saugdruck (Po) und den Kondensatordruck (Pc) und den Kältemittelmassenfluß, um die momentane Kühlkapazität (Qo) zu bestimmen,
- und Darstellen dieser momentanen Kühlkapazität (Qo) gemäß den Erfordernissen.
2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß es die folgenden Schritte aufweist:
- Messen der zum Zweck des Betätigens der Kühlanlage verbrauchten elektrischen Leistung (Pe),
- Errechnen der momentanen Effizienz (COP) der Kühlanlage durch Teilen der errechneten momentanen Kühlkapazität (Qo) durch den Wert, der für die verbrauchte elektrische Leistung (Pe) gemessen wurde,
- Darstellen dieser momentanen Effizienz (COP) gemäß den Erfordernissen.
3. Verfahren nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß es die folgenden Schritte aufweist:
- Errechnen der momentanen Effizienz (COP) der Kühlanlage,
- Verändern von Prozeßvariablen der Kühlanlage oder der Konfiguration der Kühlanlage,
- Wiedererrechnen der momentanen Effizienz (COP) des Kühlsystems,
- Wiederholen der vorstehenden Schritte gemäß den Erfordernissen.
4. Verfahren nach einem der vorstehenden Ansprüche, dadurch gekennzeichnet, daß es die folgenden Schritte umfaßt:
- Bestimmen eines maximalen erwünschten Dickungsfaktors für das Wasser im Behältertank,
- Verwenden der Werte für Po, Pc und des Kühlmittel-Massenflusses züm Bestimmen der Belastung des Kondensators (Qc),
- Bestimmen des korrekten Volumens von Zusatzwasser auf der Basis der errechneten Belastung des Kondensators (Qc) und des vorbestimmten Verdickungsfaktors,
- und Einstellen des Volumens von Zusatzwasser, das pro Zeiteinheit dem Behältertank zufließt, gemäß den Erfordernissen.
5. Verfahren nach einem der vorstehenden Ansprüche, dadurch gekennzeichnet, daß das Kühlmittel von einem Flüssigkeitsgefäß aus injiziert wird, wobei das Kühlmittel
aus dem Flüssigkeitsgefäß auf modulierende Weise in den Wärmetauscher injiziert wird.
6. Kühlanlage (20) zum Ausführen des Verfahrens nach einem der vorstehenden Ansprüche,
aufweisend einen Kühlmittelkreislauf, umfassend ein Flüssigkeitsgefäß (2) für Kühlmittel
mittels einer Auslaßleitung (23), die mit einem Verdampfer (3) verbunden ist, wobei
der Verdampfer (3) mit einem Kompressor (4) verbunden ist, wobei der Kompressor mit
einem Kondensator (6) verbunden ist, wobei der Kondensator mit dem Flüssigkeitsgefäß
(2) verbunden ist, wobei der Kondensator ein Verdampfungskondensator (6) ist, der
mit einem Wasserbehältertank (7) ausgestattet ist, der mit einer Zuführleitung (22)
zum Zuführen von Zusatzwasser an den Wasserbehältertank (7) verbunden ist, wobei die
Anlage einen Wärmetauscher (21) aufweist, der sowohl mit der Zuführleitung (22) für
den Behältertank (7) als auch mit der Auslaßleitung (23) aus dem Flüssigkeitsgefäß
(2) verbunden ist, dadurch gekennzeichnet, daß die Anlage folgendes umfaßt: Mittel zum Messen des Massenflusses von Wasser, das
durch den Wärmetauscher (21) zugeführt wird, Mittel zum Messen der Temperatur des
Wassers in der Zuführleitung stromaufwärts und stromabwärts über dem Wärmetauscher
(21), Mittel zum Errechnen der Wärmemenge, die dem Wasser im Wärmetauscher (21) zugeführt
worden ist, Mittel zum Messen der Temperatur des Kühlmittels in der Auslaßleitung
(23) stromaufwärts und stromabwärts des Wärmetauschers (21), Mittel zum Bestimmen
des Kühlmittelmassenflusses auf der Basis der errechneten Menge an Wärme, die dem
Wasser im Wärmetauscher (23) zugeführt worden ist, und der gemessenen Temperaturdifferenz
des Kühlmittels im Wärmetauscher (21), Mittel zum Messen des Saugdruckes (Po) und
zum Messen des Kondensatordruckes (Pc) des Kühlmittels, und Mittel zum Bestimmen der
momentanen Kühlkapazität (Qo) unter Verwendung der gemessenen Werte für den Saugdruck
(Po) und den Kondensatordruck (Pc).
7. Kühlanlage (20) nach Anspruch 6, dadurch gekennzeichnet, daß die Kühlanlage mit Mitteln zum Darstellen der momentanen Kühlkapazität (Qo) ausgestattet
ist.
8. Kühlanlage (20) nach Anspruch 6 oder 7, dadurch gekennzeichnet, daß sie Mittel (24, 25) zum Messen der elektrischen Leistung (Pe), die zum Zweck des
Betreibens der Kühlanlage verbraucht wird, Mittel zum Errechnen der momentanen Effektivität
(COP) der Kühlanlage (20) durch Teilen der errechneten momentanen Kühlkapazität (Qo)
durch den Wert, der für die verbrauchte elektrische Leistung (Pe) gemessen wurde,
aufweist.
9. Kühlanlage (20) nach den Ansprüchen 6 bis 8, dadurch gekennzeichnet, daß die Kühlanlage (20) Mittel zum Darstellen der momentanen Effektivität (COP) aufweist.
10. Kühlanlage (20) nach den Ansprüche 6 bis 9, dadurch gekennzeichnet, daß das System (20) Mittel zum Bestimmen eines maximalen erwünschten Verdickungsfaktors
für das Wasser im Behältertank, Mittel zum Bestimmen der Belastung des Kondensators
(Qc) unter Verwendung der Werte für Po, Pc und des Kühlmittel-Massenflusses, Mittel
zum Bestimmen des korrekten Volumens von Zusatzwasser auf der Basis der errechneten
Belastung des Kondensators (Qc) und des vorgegebenen Verdickungsfaktors und Mittel
zum Einstellen des Volumens von Zusatzwasser, das pro Zeiteinheit in den Behältertank
(7) fließt, aufweist.
11. Kühlanlage (20) nach den Ansprüchen 6 bis 10, dadurch gekennzeichnet, daß die Anlage (20) Mittel zum Injizieren von Kühlmittel aus dem Flüssigkeitsgefäß (2)
auf modulierende Weise in den Wärmetauscher (21) aufweist.
1. Procédé pour le fonctionnement d'un système frigorifique à l'aide d'un circuit réfrigérant,
dans lequel pour condenser le réfrigérant dans ledit circuit un circuit de refroidissement
par eau est utilisé, incorporant un condenseur évaporatif, les pertes d'évaporation
dudit condenseur étant complétées à l'aide d'eau d'appoint étant alimentée au condenseur
par un échangeur de chaleur au moyen duquel le liquide réfrigérant du circuit de réfrigération
est sous-refroidi, caractérisé en ce que le procédé comporte les étapes suivants:
- mesurant le débit massique d'eau livré à travers l'échangeur de chaleur,
- mesurant la différence de température dans l'eau d'appoint avant qu'elle ne soit utilisée pour refroidir le réfrigérant et après qu'elle a été utilisée pour refroidir le réfrigérant,
- calculant la quantité de chaleur qui a été livrée à l'eau,
- mesurant la différence de température du réfrigérant avant qu'il ne soit refroidi de l'eau d'appoint et après qu'il a été refroidi par l'eau d'appoint,
- déterminant le débit massique du réfrigérant sur la base de la quantité calculée de chaleur livrée à l'eau et de la différence de température mesurée dans le réfrigérant,
- mesurant la pression d'aspiration (Po) respectivement la pression de condenseur (Pc) du réfrigérant,
- utilisant les valeurs mesurées pour la pression d'aspiration (Po) et la pression de condenseur (Pc) et le débit massique de réfrigérant pour déterminer la capacité de refroidissement instantanée (Qo),
- et affichant cette capacité de refroidissement instantanée (Qo) à la demande.
2. Procédé selon la revendication 1, caractérisé en ce que le procédé comporte les étapes suivantes:
- mesurant l'énergie électrique (Pe) consumée pour faire opérer le système de refroidissement,
- calculant la performance instantanée (COP) du système de refroidissement en divisant la capacité de refroidissement instantanée calculée (Qo) par la valeur mesurée pour l'énergie électrique (Pe) consumée,
- affichant cette performance instantanée (COP) à la demande.
3. Procédé selon la revendication 1 ou 2, caractérisé en ce que le procédé comporte les étapes suivantes:
- calculant la performance instantanée (COP) du système de refroidissement,
- changeant des variables de fonctionnement du système de refroidissement ou la configuration du système de refroidissement,
- recalculant la performance instantanée (COP) du système de refroidissement,
- répétant les étapes du procédé sus-mentionnés à la demande.
4. Procédé selon l'une quelconque des revendications précédentes, caractérisé en ce que le procédé comporte les étapes suivantes:
- déterminant un facteur d'épaississement désiré maximum pour l'eau dans le récipient,
- utilisant la valeur de Po, Pc et du débit massique de réfrigérant pour déterminer la charge du condenseur (Qc),
- déterminant la quantité correcte de l'eau d'appoint sur la base de la charge calculée du condenseur (Qc) et le facteur d'épaississement prédéterminé,
- et régulant la quantité de l'eau d'appoint qui écoule vers le récipient par unité de temps à la demande.
5. Procédé selon l'une quelconque des revendications précédentes, caractérisé en ce que le réfrigérant est injecté depuis un réservoir de liquide, où le réfrigérant est
injecté depuis le réservoir de liquide vers l'échangeur de chaleur dans une manière
modulante.
6. Système de refroidissement (20) pour mettre en oeuvre le procédé selon l'une quelconque
des revendications précédentes, comprenant un circuit réfrigérant, incorporant un
réservoir de liquide (2) pour réfrigérant au moyen d'une conduite d'évacuation (23)
liée à un évaporateur (3), l'évaporateur (3) étant lié à un compresseur (4), le compresseur
étant lié à un condenseur (6), où le condenseur est lié au réservoir de liquide (2),
le condenseur étant un condenseur évaporatif (6) muni d'un récipient à eau (7), qui
est lié à une conduite d'alimentation (22) pour fournir l'eau d'appoint au récipient
à eau (7), où ce système comprend un échangeur de chaleur (21) qui est lié à la conduite
d'alimentation (22) pour le récipient (7) et aussi à la conduite d'évacuation (23)
depuis le réservoir de liquide (2), caractérisé en ce que le système comprend des organes pour mesurer le débit massique de l'eau livrée à
travers de l'échangeur de chaleur (21), des organes pour mesurer la température de
l'eau dans la conduite d'alimentation en amont et en aval sur l'échangeur de chaleur
(21), des organes pour calculer la quantité de chaleur qui a été livrée à l'eau dans
l'échangeur de chaleur (21), des organes pour mesurer le temperature du réfrigérant
dans la conduite d'évaporation (23) en amont et en aval de l'échangeur de chaleur
(21), des organes pour déterminer le débit massique du réfrigérant sur la base de
la quantité calculée de chaleur livrée à l'eau dans l'échangeur de chaleur (23) et
la différence de température mesurée du réfrigérant dans l'échangeur de chaleur (21),
des organes pour mesurer la pression d'aspiration (Po) et pour mesurer la pression
de condenseur (Pc) du réfrigérant, et des organes pour déterminer la capacité de refroidissement
instantanée (Qo) utilisant les valeurs mesurées pour la pression d'aspiration (Po)
et la pression de condenseur (Pc).
7. Système de refroidissement (20) selon la revendication 6, caractérisé en ce que le système de refroidissement est équipé d'organes pour l'affichage de la capacité
de refroidissement instantanée (Qo).
8. Système de refroidissement (20) selon la revendication 6 ou 7, caractérisé en ce que le système comporte des organes (24, 25) pour mesurer l'énergie électrique (Pe) consumée
pour faire opérer le système de refroidissement, des organes pour calculer la performance
instantanée (COP) du système de refroidissement (20) en divisant la capacité de refroidissement
instantanée calculée (Qo) par la valeur mesurée pour l'énergie électrique (Pe) consumée.
9. Système de refroidissement (20) selon les revendications 6-8, caractérisé en ce que le système de refroidissement (20) comporte des organes pour l'affichage de la performance
instantanée (COP).
10. Système de refroidissement (20) selon les revendications 6-9, caractérisé en ce que le système (20) comporte des organes pour déterminer un facteur d'épaississement
désiré maximum pour l'eau dans le récipient, des organes pour déterminer la charge
du condenseur (Qc), utilisant la valeur de Po, Pc et du débit massique réfrigérant,
des organes pour déterminer la quantité correcte de l'eau d'appoint sur la base de
la charge calculée du condenseur (Qc) et du facteur d'épaississement prédéterminé,
et des organes pour régler la quantité de l'eau d'appoint qui écoule au récipient
(7) par unité de temps.
11. Système de refroidissement (20) selon les revendications 6-10, caractérisé en ce que le système (20) comporte des organes pour injecter du réfrigérant dans un échangeur
de chaleur (21) depuis le réservoir de liquide (2) dans une manière modulante.