Method for determining operating margin of compressor

Abstract

One aspect of the present disclosure relates to a method for determining a compressor operating margin. According to an embodiment, there is disclosed a method for determining an operating margin (206) of a compressor (102) comprising a cooling circuit (101), the method comprising iteratively performing the steps of: measuring (200) one or more process variables indicative of instantaneous operation of the compressor (102); estimating (201) one or more process variables based on one or more setting parameters of the compressor (102) using a model (203) comprising a heat transfer characteristic between the compressor (102) and the cooling circuit (101), the heat transfer characteristic comprising a pollution parameter; matching (204) the estimated process variable (201) to the measured process variable (202) by varying the contamination parameter; wherein the operating margin (206) is determined (205) based on the pollution parameter.

Description

Technical Field

[0001] The invention relates to a method for determining the operating margin of a compressor and / or peripheral equipment in order to increase the availability thereof. Background Art

[0002] A compressor is a mechanical machine designed to provide gas, such as ambient air, at high pressure for applications in industrial processes and / or medical fields. Depending on the required pressure, the desired application, the desired results and other boundary conditions, one can choose from a variety of compressor technologies, such as axial compressors vs. centrifugal compressors, and oil-free compressors vs. oil-lubricated compressors.

[0003] Furthermore, the compressor may be equipped with peripheral equipment, also called supporting equipment, such as coolers, oil separators, filters or air filters, dryers and the like.

[0004] Obviously, in most industrial environments and / or in the medical field, high compressor availability without loss of performance is desired. However, like most mechanical machines, some form of degradation is inevitable over time due to factors such as the presence of rotating parts, contamination in the ambient air around the machine, exposure to large temperature differences, oil loss and other internal or external influences that may hinder and / or impair the normal operation of the compressor.

[0005] This could lead to a premature stop of the compressor without prior notice to the operator. To avoid this undesirable situation, a method is needed to determine the operating margin of the compressor. This allows estimating the remaining availability and / or taking timely action to be able to guarantee its availability.

[0006] It is therefore an object of the present invention to provide a method for determining the operating margin of a compressor comprising a cooling circuit. Summary of the invention

[0007] According to the present invention, the above object is achieved by providing, according to a first aspect of the present invention, a computer-implemented method according to claim 1 for determining an operating margin of a compressor comprising a cooling circuit, the method comprising iteratively performing the following steps:

[0008] - measuring one or more process variables indicative of instantaneous operation of the compressor;

[0009] - estimating one or more process variables based on one or more setting parameters of the compressor using a model including heat transfer characteristics between the compressor and the cooling circuit, the heat transfer characteristics including a contamination parameter;

[0010] - Matching the estimated process variables with the measured process variables by varying the pollution parameters;

[0011] Therein the operating margin is determined based on the contamination parameter and one or more setting parameters of the compressor.

[0012] A measuring step is understood to be the quantitative input of a quantity obtained from one or more observations, recordings or sampling at a specific measuring location with the aid of a suitable measuring instrument (such as a sensor), which is used to express the observed quantity as a number with relevant units that can be compared with other values ​​of the same quantity.

[0013] The estimation step is understood as the determination of the value of a quantity based on measured process quantities and / or setting parameters, which step is performed based on one or more calculations using a scientific model, which represents a technical process and / or a device with measured process quantities and / or setting parameters as input and with the value to be determined and therefore estimated as output.

[0014] The matching step is understood as making a set of variables in the system of equations converge by changing one or more parameters in the system of equations to a set of specific expected values. Therefore, the matching step is performed based on one or more calculations.

[0015] Performing the steps iteratively means performing the steps repeatedly.

[0016] Hereinafter, reference will be made to machines, compressors and / or devices, but it should also be noted that for the purpose of discussing the present invention, these terms are interchangeable. Thus, when the term "machine" is mentioned, it may refer to a compressor, a support device, or a combination of the two.

[0017] In a first step, process variables indicative of the instantaneous operation of the compressor are measured. These process variables are ambient temperature, cooling temperature, compressor temperature, current, speed, inlet pressure, outlet pressure, ambient pressure, humidity and / or flow rate. Furthermore, it is noted that this list is not exhaustive and that other process parameters indicative of the operation of the compressor may also be measured. On the other hand, it should also be noted that not all process variables are measured, but some of them are measured.

[0018] In a second step, these one or more process variables of the compressor are estimated. The estimation is performed based on one or more setting parameters of the compressor, which are used as inputs of a scientific model of the compressor, wherein the output of the model is the estimated process variable. Furthermore, as already mentioned, this step can also be performed based on the measurements performed in the first step according to an embodiment.

[0019] It should also be noted that the first and second steps can be performed in parallel and simultaneously. Therefore, the terms "first" and "second" used serve to distinguish between the different steps, but do not imply a specific temporal order and / or hierarchy between the two steps. On the other hand, it must of course be understood that estimating a process variable based on other measured process variables does mean that this measurement is performed before the estimation.

[0020] One or more process variables are estimated based on a model including heat transfer characteristics between the compressor and the cooling circuit, wherein the heat transfer characteristics include a contamination parameter.

[0021] In the case of oil-free compressors, the cooling circuit consists of several components, such as a pump, a housing of the compressor element of the compressor, a cooler, bearings, a gearbox and pipes connecting these components. These wholes together form a closed system, which means that the oil pushed by the oil pump for heat transfer is later returned to the inlet of the same pump. Alternatively, for oil-injected compression, the heat transfer can be carried out in the compressor element itself and / or the cooling circuit can be equipped with a coolant other than oil, such as water. It is important to use a model that represents the cooling circuit used and is described by the heat transfer characteristics. In the further discussion of the present invention, oil will be mentioned as a coolant, but it should be understood that other types of coolants can also be used.

[0022] The compressor generates heat during its operation which must be dissipated. To this end, oil will flow in a cooling circuit, whereby the cooling circuit is configured such that the oil will absorb heat in order to cool the heat-generating parts of the compressor. In other words, a certain mass of oil with a certain heat capacity will flow through the cooling circuit and the oil will absorb heat at certain locations in the circuit, such as at bearings, gearboxes, compressor elements, element housings and pumps, and dissipate the heat at other locations in the circuit, for example to a cooler or by radiation to the environment.

[0023] The heat transfer characteristics then become part of the model and represent the cooling circuit including the contamination parameters as described below.

[0024] Initially, a model of an ideal machine is provided to estimate the process variables, i.e. a machine without any contamination and / or defects. The difference (also called delta) between the measured and estimated process variables will in principle indicate a deviation behavior between the ideal or healthy machine and the actual machine. The larger this difference is, the greater the deviation behavior of the machine compared to a healthy machine. This difference will be further explained by this defined contamination parameter present in the model used.

[0025] For example, a contamination parameter is a parameter having a value between zero and one, wherein a value of zero indicates that the compressor cooling circuit is completely clean, i.e. in a healthy state. This condition may be further described as a condition or state in which dust and other contaminants are not present. A value of one for the contamination parameter may then indicate a condition in which the compressor cooling circuit is contaminated to such an extent that maintenance action is required. Furthermore, this may also indicate a condition in which the compressor is no longer suitable for further use without such maintenance action due to contamination of the cooling circuit.

[0026] It should also be understood that contamination will primarily occur outside the compressor, for example due to accumulation of dust particles which prevent air from entering the air-oil heat exchanger. Furthermore, it is noted that contamination of mechanical machines such as compressors, while undesirable, is unavoidable under normal operating conditions.

[0027] The contamination parameter may also take values ​​other than between zero and one and may, for example, be further normalized based on this parameter to standardize further processing and control. For example, such normalization may be performed based on the cooling surface of the cooling circuit.

[0028] Thus, the model represents a compressor including a cooling circuit and is, for example, a physical or multi-physical model comprising a set of differential equations and / or physical and / or empirical relationships describing the different physical parts of the compressor and the cooling circuit and which are mutually dependent through one or more common variables. The set of differential equations also comprises one or more parameters, such as a contamination parameter as described above, and one or more variables. Alternatively, the contamination parameter may also be a parameter in the empirical model and / or the physical relationship.

[0029] In a third step, the estimated process quantity is matched to the measured quantity by changing the pollution parameter within the model. In other words, the other parameters within the differential equations describing the compressor remain unchanged, while the pollution parameter is changed to make the estimated process quantity consistent with the measured process quantity. When the model is an empirical model and / or contains physical relationships, parameters other than the pollution parameter can be maintained unchanged to determine the value of the pollution parameter. It should also be understood that due to the sensors used and the method used to perform the matching to converge the value to the measured value, there may still be deviations between the measured and matched process variables.

[0030] Finally, the operating margin of the compressor is determined based on the contamination parameter and one or more compressor setting parameters. In other words, the estimated process variable is matched to the measured process variable by varying the contamination parameter in the model, which will be adjusted within the range of zero and one, whether normalized as described above or not. As mentioned earlier, this corresponds to a fully healthy versus fully contaminated situation, so the operating margin and future availability of the compressor can be understood given a particular use.

[0031] As mentioned previously, the different steps are done iteratively, in other words, they are performed repeatedly, thereby providing a continuous estimate of the operating margin over time.

[0032] This operating margin can then be further monitored, making it possible to estimate under which operating conditions a fault or shutdown will occur. For example, such a fault can occur when the oil temperature of the oil present in the oil circuit exceeds a predefined safety limit. Such an excess can be attributed to excessive contamination conditions in the compressor and / or cooling circuit and can therefore be derived from the value of the contamination parameter.

[0033] Another advantage is that, instead of estimating when a failure occurs, the further operational availability of the compressor can also be estimated based on the contamination parameter. This can then be predicted, for example, by limiting the range of compressor setting parameters. These setting parameters of the compressor are, for example, pressure, flow rate, power and / or optional humidity level. This limitation can then extend the availability of the compressor or the time during which it can continue to operate. This is possible because undesired but expected contamination of the compressor under normal operating conditions can be taken into account.

[0034] In other words, if it can be inferred that the machine is working suboptimally, or there is a risk that the machine will work suboptimally due to contamination, this can already be predicted by limiting the range of setting parameters. This avoids the risk of sudden failures or downtimes and prevents further damage to the machine if it continues to operate based on setting parameters that could negatively affect its further operation. Thus, the availability of the compressor can be optimized. Although the machine will be operating suboptimally, it can be ensured that it is indeed still operating.

[0035] According to an embodiment, the heat transfer characteristic further comprises a heat dissipation component comprising a power efficiency factor of the compressor.

[0036] In addition to modeling the cooling circuit itself, the heat transfer characteristics model can also include the heat dissipation component of the compressor, which is expressed via a power efficiency factor. This means that the model takes into account the expected heat generated by the compressor during normal operation. Since every machine has losses expressed as a performance or efficiency factor, the model will be more accurate if this is taken into account.

[0037] According to an embodiment, the heat dissipation component may also include an instantaneous speed factor of the compressor.

[0038] The heat generated during normal operation also depends on the rotational speed of the compressor element, which is expressed by the instantaneous speed factor. This factor ensures further accuracy of the model.

[0039] According to an embodiment, the heat transfer characteristic further comprises a heat removal component, which comprises the cooling capacity of the cooling circuit.

[0040] Not only the heat generated by the compressor during operation is taken into account, but also the cooling capacity of the cooling circuit, whereby the cooling capacity model may also include a heat transfer coefficient of the cooling circuit.

[0041] According to a second aspect of the present invention, a data processing system is disclosed, the system comprising a processing unit configured to perform the method according to the first aspect of the present invention.

[0042] According to a third aspect of the present invention, a computer program product is disclosed, which comprises computer executable instructions, and when the program is executed on a computer, is used to perform the method of the first aspect.

[0043] According to a fourth aspect of the present invention, a computer readable storage means comprising the computer program product of the third aspect is disclosed.

[0044] According to a fifth aspect of the present invention, a compressor is disclosed, comprising a data processing system according to the second aspect of the present invention.

[0045] According to a sixth aspect of the present invention, a method for determining an operating margin of a compressor comprising a cooling circuit is disclosed, the method comprising iteratively performing the following steps:

[0046] - measuring one or more process variables indicative of instantaneous operation of the compressor;

[0047] - estimating one or more process variables based on one or more setting parameters of the compressor using a model including heat transfer characteristics between the compressor and the cooling circuit, the heat transfer characteristics including a contamination parameter;

[0048] - Matching the estimated process variables with the measured process variables by varying the pollution parameters;

[0049] Therein the operating margin is determined based on the contamination parameter and one or more setting parameters of the compressor.

[0050] Furthermore, the estimating may be done based on one or more of the one or more measured process variables.

[0051] Additionally, the heat transfer characteristics may include a heat dissipation component that includes a power efficiency factor for the compressor.

[0052] The dissipative component may also include the instantaneous speed factor of the compressor.

[0053] The heat transfer characteristics may also include a heat removal component including the cooling capacity of the cooling circuit.

[0054] The cooling capacity may also include the heat transfer coefficient of the cooling circuit.

[0055] The cooling circuit may further comprise an oil circuit containing a coolant, and wherein the heat removal component further comprises a temperature difference between the coolant and the inlet air.

[0056] Furthermore, the method may include the following steps:

[0057] - Normalization of the contamination parameters based on the cooling surface of the cooling circuit.

[0058] Furthermore, the method may include the following steps:

[0059] - Limiting the range of setting parameters of the compressor based on the contamination parameters.

[0060] The process variables include one or more of the group consisting of ambient temperature, cooling temperature, compressor temperature, flow, speed, inlet pressure, outlet pressure, ambient pressure, humidity, and / or flow rate.

[0061] The setting parameters include one or more of the group consisting of pressure, flow rate, humidity level, power. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] The present invention will be further described with reference to the accompanying drawings, in which

[0063] Figure 1 schematically illustrates a compressor having a cooling circuit monitored by a controller;

[0064] Figure 2 Schematically illustrates the Figure 1 The steps of the method of the invention for determining the operating margins of the compressor and the cooling circuit in an embodiment of the invention;

[0065] Figure 3 A more detailed illustration Figure 1 The cooling circuit shown in;

[0066] Figure 4 A model including a set of inputs representing a compressor and / or cooling circuit is illustrated; and

[0067] Figure 5A and 5B The evolution of oil temperature and operating margin under different conditions is shown. DETAILED DESCRIPTION

[0068] The present invention will be described with respect to certain embodiments and with reference to certain drawings, but the invention is not limited thereto and is determined solely by the claims. The drawings described are merely schematic and non-limiting. In the drawings, for illustrative purposes, the dimensions of certain elements may be exaggerated and not drawn to scale. Dimensions and relative dimensions do not necessarily correspond to actual practical embodiments of the present invention.

[0069] Furthermore, the terms "first," "second," "third," etc., are used in the description and claims to distinguish between similar elements, and not necessarily to describe a sequential or chronological order. These terms are interchangeable under appropriate circumstances, and embodiments of the invention may be practiced in sequences other than those described or illustrated herein.

[0070] Furthermore, the terms "top", "bottom", "above", "below", etc., used in the description and claims are for descriptive purposes and not necessarily for describing relative positions. The terms so used are interchangeable under appropriate circumstances, and the embodiments of the invention described herein may be employed in orientations other than those described or illustrated herein.

[0071] Additionally, while various embodiments are referred to as "preferred embodiments," they are to be construed as exemplary means of carrying out the invention, rather than limiting the scope of the invention.

[0072] The term "comprising" used in the claims should not be interpreted as being limited to the components or steps set out below; the term does not exclude other elements or steps. The term should be interpreted as specifying the presence of the mentioned features, elements, steps or components, but does not exclude the presence or addition of one or more other features, elements, steps or components or groups thereof. Therefore, the scope of the expression "a device comprising components A and B" should not be limited to devices consisting only of components A and B. The meaning is that, with respect to the present invention, only components A and B of the device are listed, and the claims are also interpreted to also include equivalents of these components.

[0073] Figure 1 A compressor 102 comprising a compressor element 100 is schematically illustrated. When the compressor 102 is of the screw compressor type, the compressor element 100 is, for example, a screw. Furthermore, the compressor can be of the oil-free or oil-lubricated type - also called oil-injected type. However, considering the steps of the method, the presence of a cooling circuit 101 is necessary.

[0074] refer to Figure 3, which is shown in more detail in the form of a schematic diagram. The illustrated cooling circuit 101 is a closed cooling circuit, which means that a coolant (in this case oil) circulates in a closed circuit and exchanges heat with the various components of the compressor 102. The oil is circulated to one or more machine components 301, such as the compressor element 100, by means of a pump 300, where heat is removed to the oil. The oil is then cooled again in a cooler 302, for example by means of a fan 303, thereby exchanging heat with the ambient air. The oil can then also be used as a lubricant 304 for machine components (such as a gearbox) and is recirculated by the pump 300 in the cooling circuit 101.

[0075] like Figure 3 The fan 303 schematically illustrated in the diagram should be considered as a component of an air-oil heat exchanger, wherein heat can be removed from the oil to the environment, as mentioned above. Dust particles present in the ambient air can contaminate the fan 303 and / or the air-oil heat exchanger by accumulating these dust particles, thereby damaging the fan 303 and / or preventing air from passing smoothly through the air-oil heat exchanger.

[0076] The compressor element 100, and more generally the compressor 102, will further generate heat during operation, which is referred to as Q heat generated This heat is generated by various physical processes. The first process is the release of heat from the compressor due to the compression process, which is the power efficiency factor small instantaneous speed factor ω unit and compressor power P compr The compressor power can be determined using the compression model. The second process is the generation of heat by friction based on the speed at which the compressor rotates. Therefore, the heat output due to friction is a gain factor α fric and the instantaneous velocity factor ω unit The gain factor represents the friction factor of the compressor element 100 when the compressor 102 is in operation. Therefore, the general expression for the heat generated is Q heat generated (η, P compr ,ω unit , α fric , ...).

[0077] The cooling circuit 101 has a cooling capacity P cooler Characterized by cooling capacity P cooler is the capacity (poWer) that the circuit 101 can discharge via the oil in the compressor 102. This cooling capacity is also the amount of heat Q removed during operation of the compressor 102 heat removed , which is related to the oil temperature T in the circuit oil The cooling air temperature T supplied by the fan 303 air inletThe cooling capacity P corresponding to the heat discharged is proportional to the difference between the two, and the proportionality factor is equal to the heat transfer coefficient UA of the cooler. In addition, the cooling capacity also depends on whether the forced ventilation of the fan 303 is effective. The cooling air temperature itself can be modeled as a correction of the temperature in the compressor housing of the compressor 102. The cooling capacity P corresponding to the discharged heat cooler Then it becomes P cooler (fanstate, UA, T oil , T air inlet , ...) = Q heat generated .

[0078] As long as it can be assumed that the cooling circuit 101 is healthy, in other words, not contaminated, the above model can be used to determine the overall efficiency of the cooling circuit 101 and the compressor 102. In addition, the operating margin of the compressor 102 can also be determined by the above model. It is noted that the operating margin should be understood as the amplitude by which the process variable can increase while the compressor 102 can still maintain safe and efficient operation. When the cooling circuit 101 is healthy, the measured values ​​and the estimated values ​​obtained by calculation will be consistent with each other. However, when the cooler starts to clog, the heat transfer coefficient UA of the cooler will decrease. This can be achieved by introducing an additional factor β U (also called the contamination parameter) incorporates this degradation into the model, with values ​​ranging between 1 (corresponding to a healthy cooling circuit 101) and 0 (where no heat transfer occurs at all). The capacity P of the cooler is then obtained cooler (fanstate, UA, T oil , T air inlet , β U )=Q heat generated .

[0079] exist Figure 1 , a controller 103 is also illustrated, which is configured to set a set of possible setting parameters β of the compressor 102 based on the aforementioned pollution parameters. U A method for determining an operating margin of a compressor 100 including a cooling circuit 101 is performed. Figure 1 As shown in FIG. 1 , the controller 103 is configured to exchange information 104 with the compressor 102 , but it should also be understood that the controller 103 may also be an integral part of the compressor 102 .

[0080] refer to Figure 2 , further illustrating the steps performed by the controller 103. In a first step, the measurement module 202 measures process variables 200 representing and / or indicating the operation of the compressor 102. In a second step 201, these measured process variables are estimated based on the model shown in the module 203 based on one or more setting parameters of the compressor 102. In addition, as shown in Figure 2As shown in , estimates can also be made based on one or more measured process variables. For example, the result of module 202 is the measured oil temperature, and in the same example, the result of model 203 is the estimated oil temperature.

[0081] In the measurement module 202, calculations are then performed based on the above equations and based on the measured values ​​200 to further determine the cooling capacity of the cooling circuit 101. In the module 203, the expected cooling capacity and the generated heat are also estimated based on the setting parameters of the compressor 102. Therefore, this module 203 performs the necessary calculation steps to predict the temperature. It is also noted that Figure 2 It is used to illustrate the steps of the disclosed method, and all calculations can also be performed by module 203.

[0082] Figure 4 Modules 202 and 203 are further schematically illustrated. A set of inputs 401-405 are shown here, such as speed 401, pressure 402, inlet temperature 403, ventilation conditions 404 of fan 303, and oil temperature 405 at a specific time, from which a set of equations 406 such as in the above-mentioned model can be used to determine and estimate the cooling capacity as a result of the calculation.

[0083] Furthermore, the difference between the measured value and the estimated value will then be determined 204, after which the contamination parameter β can be determined via module 205. U , whether normalized or not, and based on this and a set of setting parameters for the compressor 102 , an operating margin 206 can be derived.

[0084] refer to Figure 5A and 5B , shows graphical representations of graphs 511 - 514 and 521 - 524 , wherein oil temperature 500 is expressed in ° C. on the y-axis 500 as a function of time 501 . Figure 5A Figures 511-514 represent a compressor 102 with a clean or healthy cooling circuit 101. In addition, the oil temperature changes when the ambient temperature is 20°C 511-512 and 40°C 513-514, respectively, and the compressor 102 operates at minimum values ​​511, 513 and maximum values ​​512, 514, respectively. In addition, there is a limit 502, which can be selected as a limit value at which the compressor 102 can maintain operation in a safe manner. In this example, the limit value is set at 70°C, and the corresponding area above the limit value 502 is the shutdown limit, that is, the area where the compressor 102 must be shut down due to excessive increase in oil temperature 500. In the example of Figures 511-514, there are different operating modes where the threshold or limit value is not reached.

[0085] Further references Figure 5B521-524 in FIG. 5 show an example of a compressor 102 with a contaminated cooling circuit 101, in this example the contamination rate is 85%, which corresponds to a normalized contamination parameter β of 0.85. U .

[0086] Again, there are four operation modes, namely, the compressor 102 operates at a minimum power when the ambient temperature is 20° C. 521, the compressor 102 operates at a maximum power when the ambient temperature is 20° C. 522, the compressor 102 operates at a minimum power when the ambient temperature is 40° C. 523, and the compressor 102 operates at a maximum power when the ambient temperature is 40° C. 524. It can then be noted that with a pollution parameter β corresponding to 0.85 U A dirty cooling circuit 101 and an ambient temperature of 40°C will have to shut down the compressor 102 over time, since the operating point will be within the range of the shutdown limits.

[0087] In addition, note that for the contamination parameter β U Similar graphs can be drawn for other values ​​of .

[0088] When the pollution parameter β U After being determined, based on the above method, it can then be based on the pollution parameter β U These different models for different values ​​of and a set of settings for compressor 102 determine operating margin 206. Not only can one estimate what the remaining operating margin will be over time at a certain ambient temperature, but also the possible impact when the ambient temperature increases or the exhaust pressure or compressed air consumption increases.

[0089] When the ambient temperature is 20°C and the pollution parameter β U = 0.85, the compressor 102 will remain operational because it will not enter the region where it is expected to fail - namely, exceeding the 70°C limit 502. If the ambient temperature is expected to rise to 40°C, for example, during the summer months, then it is possible to estimate what the operating margin is and thus estimate the operating margin at a certain pollution parameter β. U The time remaining until the operating point exceeds the limit value of 70° C. for a set of setting parameters of the compressor 102. Thus, timely actions can be taken, such as maintenance of the cooling circuit 101 and / or the entire compressor 102.

Claims

1. A computer-implemented method for determining an operating margin (206) of a compressor (102) comprising a cooling circuit (101), the method comprising iteratively performing the following steps: − measuring ( 200 ) one or more process variables indicative of instantaneous operation of the compressor ( 102 ); - estimating (201) the one or more process variables based on one or more setting parameters of the compressor (102) using a model (203) including heat transfer characteristics between the compressor (102) and the cooling circuit (101), the heat transfer characteristics including a contamination parameter; − matching (204) the estimated process variable (201) with the measured process variable (200) by varying the pollution parameter; Therein an operating margin (206) is determined (205) based on the contamination parameter and the one or more setting parameters of the compressor (102).

2. The computer-implemented method of claim 1, wherein the estimating (201) is also done based on one or more measured process variables (200) of the one or more measured process variables.

3. The computer-implemented method of any one of the preceding claims, the heat transfer characteristic further comprising a heat dissipation component, the heat dissipation component comprising a power efficiency factor of the compressor (102).

4. The computer-implemented method of claim 3, the dissipative component further comprising an instantaneous speed factor of the compressor (102).

5. The computer-implemented method of any one of the preceding claims, the heat transfer characteristic further comprising a heat removal component, the heat removal component comprising a cooling capacity of a cooling circuit (101).

6. The computer-implemented method of claim 5, the cooling capacity comprising a heat transfer coefficient of a cooling circuit (101).

7. The computer-implemented method of claim 6, the cooling circuit (101) comprising an oil circuit containing a coolant, and wherein the heat removal component further comprises a temperature difference between the coolant and the inlet air.

8. The computer-implemented method according to any one of the preceding claims, further comprising the steps of: − The contamination parameter is normalized (205, 206) based on the cooling surface of the cooling circuit (101).

9. The computer-implemented method according to any one of the preceding claims, further comprising the steps of: - limiting the range of setting parameters of the compressor (102) based on the contamination parameter.

10. The computer-implemented method of any of the preceding claims, the process variables comprising one or more of the group of ambient temperature, cooling temperature, compressor temperature, flow, speed, inlet pressure, outlet pressure, ambient pressure, humidity and / or flow rate.

11. The computer implemented method of any one of the preceding claims, the setting parameters comprising one or more of the group of pressure, flow rate, humidity level, power.

12. A data processing system (103) comprising a processing unit configured to perform the method according to any of the preceding claims.

13. A computer program product comprising computer executable instructions for executing the method according to any one of claims 1 to 11 when the program is executed on a computer.

14. A computer readable storage means comprising a computer program product according to claim 13.

15. A compressor (102) comprising the data processing system according to claim 14.

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