阅读说明：本技术 热值估计 (Heat value estimation ) 是由 K·莱赫蒂宁 于 2019-04-16 设计创作，主要内容包括：根据非限制性示例实施方式,提供了一种用于分析在燃烧式发动机(106)运行期间供应给该发动机(106)的燃料的方法(200),该方法(200)包括获得(202)供应给发动机(106)的燃料的温度和供应给发动机(106)的燃料的密度的相应指示；根据所指示的燃料的温度与预定义参考温度之间的关系,基于所指示的燃料的密度得出(204)经温度调整的燃料密度；以及至少基于经温度调整的燃料密度得出(206)热值,该热值描述在预定义量的燃料的燃烧期间释放的热量。(According to a non-limiting example embodiment, a method (200) for analyzing fuel supplied to a combustion engine (106) during operation of the engine (106) is provided, the method (200) comprising obtaining (202) respective indications of a temperature of the fuel supplied to the engine (106) and a density of the fuel supplied to the engine (106); deriving (204) a temperature adjusted fuel density based on the indicated density of the fuel according to a relation between the indicated temperature of the fuel and a predefined reference temperature; and deriving (206) a heating value based at least on the temperature-adjusted fuel density, the heating value describing an amount of heat released during combustion of the predefined amount of fuel.)

1. An apparatus for analyzing fuel supplied to a combustion engine (106) during operation of the engine (106), the apparatus comprising:

a fuel flow measurement assembly (108), the fuel flow measurement assembly (108) for measuring a temperature of the fuel supplied to the engine (106) and a respective indication of a density of the fuel supplied to the engine (106); and

a control entity (110), the control entity (110) for deriving one or more parameters describing an observed fuel quality based on at least the temperature of the fuel and the density of the fuel, the control entity (110) being arranged to:

deriving a temperature-adjusted fuel density based on the indicated density of the fuel according to a relationship between the indicated temperature of the fuel and a predefined reference temperature; and is

Deriving a heating value based at least on the temperature-adjusted fuel density, the heating value describing an amount of heat released during combustion of a predefined amount of the fuel.

2. The apparatus of claim 1, wherein the thermal value comprises a lower thermal value LHV, and wherein the control entity (110) is configured to:

obtaining respective estimates of water content, ash content and sulphur content of the fuel supplied to the engine; and is

Deriving the heating value based on at least the temperature adjusted fuel density and the estimated values of the water content, the ash content, and the sulfur content of the fuel.

3. The apparatus of claim 2, wherein said heating value comprises a net specific energy calculated as a second order function of said temperature adjusted fuel density, said net specific energy being adjusted by a correction term derived as a function of said water content, said ash content, and said sulfur content of said fuel.

4. The device of claim 3, wherein the net specific energy can be calculated using the formula:

where ρ is_adjRepresents the temperature-adjusted fuel density (in kilograms per cubic meter), w, at the reference temperature of 15 degrees Celsius_wRepresents the water content (expressed as a mass percentage), w, of the fuel_aRepresents the ash content (expressed as a mass percentage), w, of the fuel_sRepresents the sulphur content (expressed as mass percentage) of the fuel, and wherein a, B, C, a, B and C represent respective predefined constant values.

5. The apparatus of claim 4, wherein A, B, C, a, B, and C are set to the following predefined values:

A＝8.802*10^-6，

B＝3.167*10^-3，

C＝46.704，

a＝0.01，

b is 0.0942, and

c＝0.02449。

6. an arrangement according to any one of claims 1-5, wherein the control entity (110) is arranged to derive the temperature adjusted fuel density via using a predefined transfer function that converts the indicated density of the fuel at the indicated temperature of the fuel into the temperature adjusted fuel density at the predefined reference temperature.

7. The apparatus of claim 6, wherein the transfer function comprises a mapping table derived based on experimental data, the mapping table providing a mapping from a plurality of fuel densities in a first predefined range at a plurality of fuel temperatures in a second predefined range to corresponding temperature-adjusted fuel densities at the predefined reference temperature.

8. The apparatus of any one of claims 1 to 7, wherein the predefined reference temperature is 15 degrees Celsius.

9. The arrangement according to any of claims 1-8, wherein the fuel comprises surplus fuel, such as heavy fuel oil HFO.

10. The apparatus according to any one of claims 1 to 9, wherein the control entity (110) is configured to perform at least one of:

estimating a specific fuel consumption SFOC value based at least in part on the heating value,

estimating a mass of the fuel supplied to the engine (106) based at least in part on the heating value,

adjusting operation of the engine (106) and/or adjusting the fuel supplied to the engine (106) based at least in part on the heating value,

displaying, via a user interface coupled to the control entity (110), an indication of the derived heating value to enable adjustment of operation of the engine (106) and/or adjustment of the fuel supplied to the engine (106) based at least in part on the heating value.

11. The apparatus of claim 10, wherein the fuel flow measurement assembly (108) comprises a coriolis-type mass flow meter.

12. A fuel quality monitoring device comprising a device according to any one of claims 1 to 11, wherein the fuel flow measuring assembly (108) is arranged in a fuel supply line (102) between a fuel tank (104) and the engine (106) to measure the temperature of the fuel supplied to the engine (106) and the density of the fuel supplied to the engine (106).

13. The fuel quality monitoring device according to claim 12, wherein the fuel flow measuring assembly is arranged in the following positions of the fuel supply line (102): at this location, the fuel is heated to a temperature at which the fuel is supplied to the engine (106).

14. A method (200) for analyzing fuel supplied to a combustion engine (106) during operation of the engine (106), the method (200) comprising:

obtaining (202) respective indications of a temperature of the fuel supplied to the engine (106) and a density of the fuel supplied to the engine (106);

deriving (204) a temperature adjusted fuel density based on the indicated density of the fuel according to a relation between the indicated temperature of the fuel and a predefined reference temperature; and

deriving (206) a heating value based at least on the temperature-adjusted fuel density, the heating value describing an amount of heat released during combustion of a predefined amount of the fuel.

15. The method (200) of claim 14, wherein the heating value comprises a lower heating value LHV, the method (200) comprising:

obtaining respective estimates of water content, ash content and sulphur content of the fuel supplied to the engine; and

deriving (206) the heating value based on at least the temperature-adjusted fuel density and the estimated values of the water content, the ash content, and the sulfur content of the fuel.

16. The method of claim 15, wherein the heating value comprises a net specific energy calculated as a second order function of the temperature adjusted fuel density, the net specific energy being adjusted by a correction term derived as a function of the water content, the ash content, and the sulfur content of the fuel.

17. The method of claim 16, wherein the net specific energy is calculated using the formula:

where ρ is_adjRepresents the temperature-adjusted fuel density (in kilograms per cubic meter), w, at the reference temperature of 15 degrees Celsius_wRepresents the water content (expressed as a mass percentage), w, of the fuel_aRepresents the ash content (expressed as a mass percentage), w, of the fuel_sRepresents the sulphur content (expressed as mass percentage) of the fuel, and wherein a, B, C, a, B and C represent respective predefined constant values.

18. The method of claim 17, wherein a, B, C, a, B, and C are set to the following predefined values:

A＝8.802*10^-6，

B＝3.167*10^-3，

C＝46.704，

a＝0.01，

b is 0.0942, and

c＝0.02449。

19. the method of any of claims 14-18, wherein deriving the temperature-adjusted fuel density comprises: converting the indicated density of the fuel at the indicated temperature of the fuel to the temperature-adjusted fuel density at the predefined reference temperature using a predefined conversion function.

20. The method of claim 19, wherein the transfer function comprises a mapping table derived based on experimental data, the mapping table providing a mapping from a plurality of fuel densities in a first predefined range at a plurality of fuel temperatures in a second predefined range to corresponding temperature-adjusted fuel densities at the predefined reference temperature.

21. The method of any of claims 14 to 20, wherein the predefined reference temperature is 15 degrees celsius.

22. The method according to any one of claims 14-21, wherein the fuel comprises residual fuel, such as heavy fuel oil HFO.

23. The method of any of claims 14 to 22, further comprising at least one of:

estimating a specific fuel consumption SFOC value based at least in part on the heating value,

estimating a mass of the fuel supplied to the engine (106) based at least in part on the heating value,

adjusting operation of the engine (106) and/or adjusting the fuel supplied to the engine (106) based at least in part on the heating value,

displaying, via a user interface coupled to the control entity (110), an indication of the derived heating value to enable adjustment of operation of the engine (106) and/or adjustment of the fuel supplied to the engine (106) based at least in part on the heating value.

24. The method according to any one of claims 14 to 23, the method comprising:

measuring the temperature of the fuel supplied to the engine (106) and the density of the fuel supplied to the engine (106) using a fuel flow measurement assembly (108) disposed in a fuel supply line (102) between a fuel tank (104) and the engine (106).

25. The method of claim 24, wherein the fuel flow measurement assembly (108) comprises a coriolis-type mass flow meter.

26. The method of claim 24 or 25, wherein the fuel flow measuring assembly (108) is arranged in the following positions of the fuel supply line (102): at this location, the fuel is heated to a temperature at which the fuel is supplied to the engine (106).

27. A computer program comprising computer readable program code configured to cause performance of the method according to any one of claims 14 to 26 when the program code is run on one or more computing devices.

Technical Field

The present invention relates to estimation of the heating value of fuel supplied to an engine.

Background

The heating value, which describes the amount of heat released during combustion for a given amount of a particular fuel, may be used to describe the amount of energy obtained from the particular fuel. In other words, the heating value serves as an indication of the energy content of a particular fuel. Thus, when the heating value is applied to a fuel supplied to a given combustion engine, it describes the mechanical energy that can be obtained from the particular fuel by operation of the given combustion engine. Since the quality of a fuel varies in terms of the mechanical energy available therefrom, the heating value of a particular fuel may be used as a metric that can yield, on the one hand, an indication of the fuel consumption of a given combustion engine and, on the other hand, an indication of the actual efficiency of the given combustion engine.

Thus, from the perspective of an engine operator, a reliable estimation of the heating value of the fuel actually supplied to the combustion engine provides valuable information about the fuel quality in terms of the mechanical energy available from it via operation of the combustion in the engine, while at the same time the heating value also enables monitoring and/or estimation of various aspects of the engine operation, such as the efficiency of the combustion engine, the fuel consumption of the combustion engine and the emissions produced by the combustion of the fuel by the combustion engine.

In the context of combustion engines that rely on the combustion of residual fuel, such as Medium Fuel (MFO) or Heavy Fuel (HFO), one measure of interest for energy content is the Low Heating Value (LHV), which may be expressed as an energy content per mass unit (e.g., megajoules per kilogram), and which may be calculated, for example, in accordance with ISO 8217: 2012 annex E net specific energy at point e.2. For distillate fuels, LHV can be calculated as according to ISO 8217: 2012 annex E net specific energy at point e.3. While the LHV or corresponding measure of fuel quality serves as a useful indicator of remaining fuel quality, currently known methods of obtaining such a measure of quality require analysis of fuel samples in a laboratory environment, which not only makes online monitoring of fuel quality and engine efficiency impossible, but also makes monitoring these aspects related to fuel an expensive and time consuming process.

Disclosure of Invention

In view of the above, it is an object of the present invention to provide a technique that enables a rapid and reliable calculation or estimation of the heating value of the remaining fuel to facilitate an online estimation of fuel quality, engine efficiency, fuel consumption and/or emissions resulting from the combustion of the fuel.

The object of the invention is achieved by an apparatus, a method and a computer program as defined in the respective independent claims.

According to an example embodiment, there is provided an apparatus for analysing fuel supplied to a combustion engine during operation of the engine, the apparatus comprising a fuel flow measuring assembly for measuring a temperature of fuel supplied to the engine and a corresponding indication of a density of fuel supplied to the engine; and a control entity for deriving one or more parameters describing an observed fuel quality based on at least the temperature of the fuel and the density of the fuel, the control entity being arranged to: deriving a temperature-adjusted fuel density based on the indicated density of the fuel according to a relationship between the indicated temperature of the fuel and a predefined reference temperature; and deriving a heating value describing an amount of heat released during combustion of the predefined amount of fuel based at least on the temperature adjusted fuel density.

According to another example embodiment, there is provided a method for analysing fuel supplied to a combustion engine during operation of the engine, the method comprising: obtaining respective indications of a temperature of fuel supplied to the engine and a density of the fuel supplied to the engine; deriving a temperature-adjusted fuel density based on the indicated density of the fuel according to a relationship between the indicated temperature of the fuel and a predefined reference temperature; and deriving a heating value based at least on the temperature-adjusted fuel density, the heating value describing an amount of heat released during combustion of the predefined amount of fuel.

According to another example embodiment, a computer program is provided, comprising computer readable program code configured to cause at least the method according to the example embodiments described hereinbefore to be performed, when said program code is run on one or more computing devices.

The computer program according to example embodiments may be embodied on a volatile or non-volatile computer-readable recording medium, for example as a computer program product comprising at least one computer-readable non-transitory medium having program code stored thereon, which, when executed by one or more apparatuses, causes the one or more apparatuses to at least perform the methods according to example embodiments described hereinbefore.

The exemplary embodiments of the invention presented in this patent application should not be interpreted to pose limitations to the applicability of the appended claims. The verb "to comprise" and its derivatives are used in this patent application as an open limitation that does not exclude the presence of other features than those listed. The features described below may be freely combined with each other, unless explicitly stated otherwise.

Some of the features of the invention are set forth in the appended claims. The aspects of the invention, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of certain exemplary embodiments when read in connection with the accompanying drawings.

Drawings

Embodiments of the invention are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings and in which:

FIG. 1 schematically illustrates a framework for online analysis of fuel quality according to an example;

FIG. 2 illustrates a method according to an example; and

fig. 3 shows a block diagram of some elements of an apparatus according to an example.

Detailed Description

Combustion engines such as Internal Combustion Engines (ICEs) may be applied in demanding industrial environments, such as power plants, ships, oil rigs and other offshore platforms, etc., where a single engine or a multiple (e.g., two or more) engine system may be applied as a supply of mechanical energy for propulsion in a ship or as an input to a generator to provide electrical power. In general, in such usage scenarios, the engine is operated continuously for a long time, and high efficiency operation is important in terms of keeping fuel consumption and emissions as low as possible. The combustion engine may be capable of combusting a distillate fuel, a residual fuel, or any of these two fuels. One of the differences between these two fuel types is their viscosity: distillate fuels have a lower viscosity and therefore they can be supplied (e.g. pumped) at a relatively low temperature for combustion in an engine, while the remaining fuel has a higher viscosity and it is generally necessary to heat the remaining fuel to provide the viscosity so that it can be pumped for combustion in the engine. Examples of remaining fuel types suitable for use in ICEs of the type outlined above include Medium Fuel (MFO) or Heavy Fuel (HFO). Residual fuels such as HFO have the advantage of low cost, while on the other hand, due to their high viscosity, they need to be heated to a temperature in the range of around 100 degrees celsius before use to ensure that the viscosity level is able to pump the residual fuel to the engine. Another disadvantage of residual fuels is that they often also include impurities, such as water, ash and/or sulfur, which may reduce the energy value of the fuel to some extent.

The present disclosure describes a technique that enables on-line analysis to assess the heating value of fuel supplied to one or more engines. Such monitoring of fuel quality provides valuable information, for example engine operation may be adjusted to try to optimize engine operating efficiency, fuel consumption and/or emissions produced, taking into account observed fuel quality as much as possible. Monitoring of the fuel mass also provides further input for estimating or calculating the actual efficiency of the engine, which may be erroneously estimated if possible variations in fuel mass are not taken into account. Furthermore, continuous monitoring of engine efficiency provides valuable additional information about the condition of the engine over a longer period of time, as inefficient operation (due to poor fuel quality) obviously requires combustion of a greater amount of fuel to obtain a particular power output from the engine, which in turn can lead to increased engine friction and wear compared to engine operation using higher quality fuel. Furthermore, such monitoring of fuel quality further enables a fact-based feedback to the fuel supplier regarding the actually observed fuel quality.

Fig. 1 schematically illustrates a framework for online analysis of fuel quality according to an example, including a fuel supply line 102 from a fuel tank 104 to an engine 106. The engine 106 may include, for example, a combustion engine, such as an internal combustion engine. Further, a fuel flow measurement assembly 108 is disposed in the fuel supply line between the fuel tank 104 and the engine 106. The fuel flow measurement assembly is communicatively coupled to the control entity 110 and arranged to provide the control entity 110 with one or more measurement signals describing fuel flow characteristics in the fuel supply line 102, the control entity 110 being arranged to derive one or more parameters describing the observed fuel quality based on the fuel flow characteristics indicated in the one or more measurement signals. The one or more parameters describing the observed fuel quality may include, for example, a heating value describing an amount of heat released during combustion of a predefined amount of the fuel (e.g., LHV).

It should be noted that the example of fig. 1 is a conceptual example, and many elements required in a realistic solution to providing fuel supply to the engine 106 are omitted, and may be varied or supplemented in a number of ways without departing from the scope of the fuel quality monitoring techniques described in this disclosure. As one example of this, the fuel flow measurement assembly 108 may include a single fuel flow measurement entity, two or more fuel flow measurement entities disposed in a single physical entity or otherwise disposed at the same location in the fuel supply line 102, two or more fuel flow measurement entities in separate individual physical entities disposed at the same location or different locations of the fuel supply line 102, and so forth. As another example, the control entity 110 may be co-located with other elements depicted in the example of fig. 1 (e.g., provided as part of the control system of the engine 104) or it may be remotely located. Furthermore, the control entity 110 should be construed as a logical entity, which may be provided as one or more separate entities or components, some of which may be co-located with other elements depicted in the example of fig. 1, and some of which may be remotely located. However, the framework of fig. 1 is sufficient to describe various characteristics of the online fuel quality monitoring technique according to the present disclosure. However, some examples of using the disclosed fuel quality monitoring techniques via the fuel supply line 102 will be described later herein as potentially involving more entities in order to illustrate various advantageous examples of implementing the fuel quality monitoring techniques.

Reference herein to "on-line" fuel quality monitoring relates to the immediate monitoring of the fuel quality actually supplied to the engine 106 during operation thereof. Along the lines outlined above, the advantages that such online fuel quality monitoring yields include the possibility of estimating or calculating parameters describing the actual efficiency of the engine with improved accuracy and/or reliability, which results in obtaining information that is useful in both short-term and long-term monitoring of engine conditions: for short-term monitoring, the indication of observed fuel quality may, for example, be able to distinguish between changes in engine efficiency caused by changes in fuel quality and changes caused by certain other factors (e.g., engine failure), while for long-term monitoring, the history of observing fuel quality indications may be useful in assessing whether changes in engine efficiency over the same period of time follow the observed fuel quality, or whether (also) there are other factors that lead to long-term trends in engine efficiency (e.g., engine usage continues to be less than optimal, maintenance of the engine is compromised or ignored....). Further, "on-line" fuel quality monitoring may also allow for (immediate) corrective action to be performed and/or operation of the engine 106 to account for observed fuel quality that does not meet predefined criteria, and further ensure that the observed quality metric is indicative of the quality of fuel actually supplied to the engine 106 at a particular time.

The online fuel quality monitoring techniques described in this disclosure may be particularly beneficial for engines designed to burn liquid residual fuel (e.g., MFO or HFO as mentioned above). However, application of the disclosed fuel quality monitoring techniques is not limited to residual fuel, but is also applicable to other liquid fuel types.

The fuel flow measurement assembly 108 is arranged to measure a characteristic of the fuel flow in the fuel supply line 102 and to provide one or more measurement signals describing the measured characteristic of the fuel flow in the fuel supply line 102 to the control entity 110. Preferably, the fuel flow measurement assembly 108 is arranged to measure a characteristic of the fuel flow supplied to the engine 106 from the fuel supply line 102 so as to reflect as closely as possible the characteristic of the fuel received by the engine 106. In one example, the measured fuel flow characteristics are directly indicative of fuel temperature and fuel density. In another example, the measured characteristic includes a characteristic from which a fuel temperature and/or a fuel density can be derived (another of which may be directly indicated). The fuel flow measurement assembly 108 may also be arranged to measure other characteristics of the fuel flow.

Here, it should be noted that the fuel flow measurement assembly 108 substantially measures the fuel flowing in the fuel flow measurement assembly 108, and that the information conveyed in the measurement signal obtained from the flow measurement assembly 108 does not take into account internal fuel leakage, for example, in the fuel supply line 102, and/or in components arranged in the engine 108. However, such factors that may affect the amount of fuel actually burned in the engine are system and engine specific and may be considered in the following manner: by adjusting one or more fuel quality parameters (e.g. heating value) derived in the control entity 110 accordingly, or otherwise taking into account one or more fuel quality parameters derived in the control entity 110 in view of such factors.

In one example, the fuel flow measurement assembly 108 includes a single entity arranged to measure the fuel temperature and the fuel density (possibly with one or more other characteristics of the fuel). One example of such a measurement entity comprises one or more mass flow meters arranged to measure the fuel temperature and the fuel density. Various flow meters suitable for this purpose are known in the art, and specific examples in this regard include Coriolis (Coriolis) type mass flow meters. In another example, the fuel flow measurement assembly 108 may include separate entities for measuring the fuel temperature and the fuel density. As one example of this, the fuel flow measurement assembly 108 may include one or more temperature sensors arranged to measure the fuel temperature and one or more flow meter assemblies arranged to measure the fuel density, where the respective temperature sensors may be arranged to measure the fuel temperature in or near the respective mass flow meter assemblies. Also in this arrangement, each mass flow meter assembly may comprise a respective coriolis type mass flow meter. In such an arrangement, the flow meter assembly may comprise a single entity arranged to directly provide the fuel density measurement, or it may comprise two or more sub-entities, wherein each sub-entity is arranged to provide a respective measurement value, the combination of which enables to derive the fuel density (e.g. in the control entity 110). As an example of the latter method, two or more sub-entities may be arranged to measure the mass of fuel supplied to the engine 106 and the volume of fuel supplied to the engine 106, respectively.

As previously described, the fuel flow measurement assembly 108 is communicatively coupled to the control entity 110. In this regard, the fuel flow measurement assembly 108 is arranged to provide one or more measurement signals to the control entity 110, the control entity 110 being arranged to derive one or more parameters describing the observed fuel quality based on information received in the measurement signals. The measurement signals include respective electrical signals that convey information describing the current value of the fuel property measured in the fuel flow measurement assembly 108. The measurement signal may comprise a corresponding analog signal or a digital signal. As one example of this, respective analog signals may be employed that each exhibit a voltage or current that may be converted by the control entity 110 into a respective characteristic (e.g., temperature or density) of the fuel flow. As another example, respective digital signals may be employed that each convey digital information indicative of a respective characteristic (e.g., temperature or density) of the fuel flow. In the context of applying a digital signal as the measurement signal, a single digital signal may convey information related to multiple characteristics of the fuel flow (e.g., temperature and density).

As previously mentioned, the control entity 108 is arranged to derive one or more parameters describing the observed fuel quality based on the fuel flow characteristics indicated in the one or more measurement signals. In this regard, the control entity 108 may be arranged to perform the steps of the method 200 illustrated by the flow chart in fig. 2.

The method 200 begins by obtaining respective indications of observed fuel temperature and observed fuel density indicated in one or more measurement signals (as shown in block 202), and deriving a temperature-adjusted fuel density based on the indicated fuel density according to a relationship between the observed fuel temperature and a predefined reference temperature (as shown in block 204). The method 200 also includes deriving one or more parameters describing the observed fuel mass based on the temperature-adjusted fuel density (as shown in block 206). The one or more parameters describing the observed fuel mass may include, for example, a heating value describing an amount of heat released during combustion of a predefined amount of the fuel in the engine 106. The method 200 may be supplemented and/or modified in a number of ways, such as described in the non-limiting examples provided below.

Referring back to the operations described with reference to block 202 of FIG. 2, the observed fuel temperature and the observed fuel density may be obtained from one or more measurement signals received via the fuel flow measurement assembly 108 described above via a number of non-limiting examples. Along the lines described above, in one example, the control entity 108 may receive respective (direct) indications of fuel temperature and fuel density. In another example, the control entity 108 may receive a direct indication of, for example, a fuel temperature and a corresponding indication of one or more fuel flow characteristics that enable derivation of a fuel density in the control entity 108 (e.g., a mass of fuel supplied to the engine 106 and a volume of fuel supplied to the engine), and calculate the fuel density from the fuel flow characteristics (e.g., a mass of fuel divided by a volume of fuel).

Referring back to the operations described with reference to block 204 of FIG. 2, deriving the temperature-adjusted fuel density may include converting the observed fuel density at the observed fuel temperature to a temperature-adjusted fuel density at the predefined reference temperature using a predefined conversion functionThe adjusted fuel density. For example, the conversion function may be provided as a mapping table stored in a memory accessible by the control entity 110, possibly accompanied by a mapping function. The lookup table may also be referred to as a lookup matrix, a mapping table, or a mapping matrix. Hereinafter, the term mapping table is mainly applied. The conversion is used to enable mapping of an observed fuel density at an observed fuel temperature to ρ at a predefined reference temperature_minTo rho_maxA corresponding temperature-adjusted fuel density within a predefined range of. The transfer function may be designed for distillation fuel or a predefined type of residual fuel, such as HFO or MFO. Non-limiting examples of transfer functions are provided below.

According to one example, the conversion function involves a mapping table and a mapping function. The mapping table may include a list of table entries, each table entry including a temperature-adjusted fuel density ρ_jCandidate values and corresponding adjustment factors F_jPairs of candidate values that can be applied via the following mapping function to identify and observe the fuel density ρ_obsAnd observing the fuel temperature T_obsCorresponding reference temperature T_refTemperature adjusted density of_adj：

ρ_adj＝ρ_obs/(1-F_adj*(T_obs-T_ref))。

In particular, deriving the temperature-adjusted fuel density using the mapping function and the mapping table may include searching the mapping table to identify a mapping table entry j that includes the temperature-adjusted fuel density ρ_jCandidate values and corresponding adjustment factors F_jCandidate values, using a mapping function, to yield the temperature-adjusted fuel density ρ closest to table entry j_jTemperature-adjusted fuel density ρ of a candidate value_adj. Thus, the temperature-adjusted fuel density ρ in the identified map entry_jThe candidate value may be used as the temperature-adjusted fuel density ρ_adj。

The above examples relating to a conversion function involving a mapping table and a mapping function assume that a nearest neighbor search is performed in the mapping table, whereinTemperature-adjusted fuel density ρ in the identified map entry_jThe candidate value is applied, for example, as the temperature-adjusted fuel density ρ_adj. In another example, assume a temperature-adjusted fuel density ρ in the identified map entry_jThe candidate value and the corresponding temperature-adjusted fuel density ρ obtained via use of the mapping function_adjNot (complete) matching, the temperature-adjusted fuel density ρ obtained in value by applying a mapping function in the above identification of mapping table entries may be obtained by applying a suitable interpolation technique_jTwo temperature-adjusted fuel densities ρ having the closest candidate values_jCandidate values to derive a temperature adjusted fuel density ρ_adjThe final value of (c).

In the above example relating to a conversion function comprising a mapping table and a mapping function, in a table entry of the mapping table the factor F is adjusted_jThe value of the candidate value is adjusted with the temperature of the fuel density ρ_jThe candidate value increases and decreases. Therefore, the effect of the temperature adjustment is to observe the fuel density ρ_obsTemperature-adjusted fuel density ρ adjusted to a higher value_adjWhile the degree of applied temperature adjustment decreases with increasing fuel density and with the observed fuel temperature T_obsWith a reference temperature T_refThe difference between them increases.

According to another example, the transfer function may be provided via a mapping table comprising a two-dimensional table in which each row represents a respective (observed) fuel density within a predefined range defined by a respective minimum fuel density and maximum fuel density, and each column represents a respective (observed) fuel temperature within a predefined range defined by a respective minimum temperature and maximum temperature. In a variation of this method, each column may represent a respective difference between the (observed) fuel temperature and the reference temperature. Thus, each cell of the two-dimensional table represents a respective combination of (observed) fuel density and (observed) fuel temperature (or difference of (observed) fuel temperature from a reference temperature) and includes a respective fuel density at the reference temperature assigned for the respective combination of observed fuel density and observed fuel temperature (or temperature difference).

Thus, the temperature-adjusted fuel density may be found by identifying a row in the two-dimensional table representing the (observed) fuel density closest to the observed fuel density and identifying a column in the two-dimensional table representing the (observed) fuel temperature closest to the observed fuel temperature (or identifying a column in the two-dimensional table representing the temperature difference closest to the difference between the observed fuel temperature and the reference temperature), and applying the fuel density at the reference temperature found in the cell defined by the identified row and column as the temperature-adjusted fuel density.

In a variation of the above example, the roles of the rows and columns of the two-dimensional table may be reversed such that each row represents a respective (observed) fuel temperature (or observed temperature difference) and each column represents a respective (observed) fuel density. In a further variation of the above example, the mapping table comprises a respective sub-table for each of a plurality of (observed) fuel temperatures within the predefined temperature range (or for each of a plurality of differences between the observed fuel temperature and the reference temperature), wherein each sub-table comprises a respective plurality of table entries covering a respective plurality of (observed) fuel densities within the predefined density range, wherein each table entry maps a respective (observed) fuel density ρ_jCorresponding fuel density ρ mapped to a reference temperature_adj. In a further variation of the above example, the roles of the sub-tables and their contents may be reversed such that each sub-table is provided for a respective (observed) fuel density within a predefined range, and the table entries of each sub-table cover a plurality of (observed) fuel temperatures (or differences between observed fuel temperatures and reference temperatures) within the predefined temperature range for the respective (observed) fuel density.

The reference temperature may be any desired temperature. For example, the reference temperature may be 15 degrees celsius, which is according to ISO 8217: 2012 appendix E gives the temperature of LHV.

The above non-limiting example with respect to the transfer function implicitly assumes the availability of a single reference temperature. In other examples, respective transfer functions may be provided for a plurality of different reference temperatures, wherein each transfer function may be provided, for example, using one of the example methods described above. In this context, the temperature-adjusted fuel density is initially obtained by: the temperature adjusted fuel density is found by selecting a transfer function of interest and applying the selected transfer function in view of the observed fuel density and the observed fuel temperature.

The conversion function (e.g., mapping table), or the mapping table and associated mapping function as a conversion function, may be derived based on experimental data collected over time. For example, such experimental data may include a relatively large number of data points covering the range from T_minTo T_maxAt a plurality of different fuel temperatures within a predefined range of_minTo rho_maxAnd a corresponding measured fuel density value at a reference temperature. For example, data points of such experimental data may be obtained using measurements of one or more engines during their normal use (e.g., in a power plant or ship), while corresponding fuel density values at a reference temperature may be obtained via laboratory analysis of the fuel used in collecting the respective data points. As another example, both data points of the experimental data and corresponding fuel density values at the reference temperature may be obtained under laboratory conditions.

Referring back to the operations described with respect to block 206 of fig. 2, deriving one or more parameters describing observed fuel quality, as previously described, may include: a heating value is derived based on the temperature adjusted fuel density. Deriving the heating value based on the temperature adjusted fuel density rather than directly using the observed fuel density as a basis for the derivation is advantageous because it results in a more accurate and reliable derivation of the heating value: for example, in the case of residual fuels such as MFO and HFO, the fuel density may even decrease significantly with increasing temperature, while on the other hand such fuels typically need to be heated to adjust the fuel viscosity to a level that makes the fuel suitable for being supplied to the engine 106. This is particularly evident in the case of HFOs, where the temperature when fuel is supplied to the engine 106 typically needs to be above 100 degrees to ensure a suitable viscosity, whereas in the case of MFOs the temperature of the fuel supplied to the engine 106 may be in the range of about 30 to 40 degrees celsius. Since the operating temperature depends on the characteristics of the engine 106 and the fuel supplied to the engine 106, the observed fuel density is typically obtained at a temperature different from the reference temperature. This difference in fuel density increases as the difference between the reference temperature and the actual measured temperature increases, while on the other hand, when relying on fuel density measurements that reflect the fuel flow characteristics at the temperature at which fuel is supplied to the engine 106, it is expected that the reliability and accuracy of the fuel quality analysis will increase. Thus, since the temperature of the fuel supplied to the engine 106 may be significantly higher than the reference temperature, directly using the observed fuel density to estimate the heating value may in many cases produce inaccurate or even very inaccurate results.

A specific, but non-limiting, example of an applicable heating value is the aforementioned Lower Heating Value (LHV). One well-known LHV estimation method is ISO 8217: 2012 appendix E, where the reference temperature is defined as 15 degrees celsius. In other examples, different methods for estimating the LHV and/or different reference temperatures may be applied. On the other hand, as previously described, a typical temperature (e.g., at which the remaining fuel, such as MFO or (especially) HFO, is supplied to the engine 106) may be significantly higher than the reference temperature, which makes it infeasible to calculate the LHV using the observed fuel density (at or near the temperature at which the fuel is supplied to the engine 106) directly. Instead, for example, include a method according to ISO 8217: 2012, annex E (or derivatives thereof) the LHV of the net specific energy can be calculated based on the temperature adjusted fuel density to improve the accuracy and reliability of the resulting LHV.

While the main contributor to the fuel heating value is the observed (but temperature adjusted) fuel density, and thus a reasonable heating value estimate can be obtained directly from the temperature adjusted fuel density, without taking into account other factors, further improvements in the accuracy and reliability of the heating value estimate can be provided by taking into account the adverse effects of predefined impurities typically present in the fuel. Examples of such impurities include water, ash and/or sulfur, which may be naturally present in the fuel and/or (accidentally) mixed into the fuel. In most practical use cases, the fuel supplied to the engine 106 is supplied from a so-called day tank, which contains fuel that has been subjected to a cleaning process to remove (most of) water and other impurities that are detrimental to the efficiency of the engine 106.

Thus, the control entity 110 may obtain corresponding estimates of the water content in the fuel, the ash content in the fuel and the sulphur content in the fuel. For example, these estimates may be obtained based on experimental data obtained via laboratory analysis of fuel obtained from a particular fuel source. The respective estimates of water content, ash content and sulphur content may be provided as respective average values based on available experimental data. While such estimates may not perfectly reflect the corresponding characteristics of the actual fuel flow in the fuel supply line 102, practical studies have shown that they still help to improve the accuracy and reliability of the heating value estimates.

The LHV dependent on the temperature adjusted fuel density yields may be exactly ISO 8217: 2012 appendix E or a modified version thereof. In general, the LHV, the value of which is further adjusted by a correction term that introduces the degree of contribution of impurities included in the fuel, may be calculated as a second order function of the temperature-adjusted fuel density, the correction term being derived as a function of the water content, ash content and sulfur content of the fuel. As an example in this respect, ISO 8217: 2012 generalized version of the formula provided in appendix E is calculated as the net specific energy Q_RnpLHV of (2):

where ρ is_adjDenotes the temperature adjusted fuel density (in kilograms per cubic meter), w, at a reference temperature of 15 degrees Celsius_wRepresents the water content (expressed as a mass percentage) of the fuel, w_aRepresents the ash content (expressed as mass%) of the fuel, and w_sIndicates the sulfur content of the fuel (expression)In mass percent). According to ISO 8217: 2012 appendix E, the constants a, B, C, a, B and C may be set to the following values for calculating LHV of HFO or MFO:

constant number	According to ISO 8217: 2012 annex E values
		A	8.802*10-6
B	3.167*10-3
		C	46.704
a	0.01
		b	0.0942
c	0.02449

In other examples (relating to FIFO or MFO or other types of fuels), an adjusted version of the above formula may be applied, where the adjustment may involve adjustment of one or more of the constants a, B, C, a, B, and C. Alternatively or additionally, the adjustment of the formula may comprise omitting a correction term that takes into account the degree of contribution of the impurities comprised in the fuel, or deriving the correction term as a different function of one or more of: water content, ash content and sulphur content of the fuel.

The control entity 110 may be arranged to directly use the derived thermal value and/or may store the thermal value in a memory for subsequent use. For the latter approach, the memory may comprise a memory (directly) accessible by the control entity 110 or a memory in another device or entity. In the latter scenario, the act of storing the thermal value in the memory further comprises transmitting the derived thermal value to another device or entity for storage therein via a communication network available to the control entity 110.

As an example, directly applying the thermal value in the control entity 110 may include: a fuel consumption indication (e.g., specific fuel consumption (SFOC)) is derived based at least in part on the derived heating value (e.g., LHV). By way of example, SFOC can be derived as defined in the ISO-3046 standard, for example as follows:

wherein the content of the first and second substances,

and is

Where K denotes a ratio indicating power, oc denotes a power adjustment factor, and P denotes_xDenotes the pressure during the measurement (in hPA), P_raRepresenting the standard reference pressure (in 1000 hPA), m represents an index that can be set, for example, to a value of 0.7, T_raIndicating the reference air temperature (in K, e.g. T)_ra＝298K)，T_xPresentation measurementAir temperature (in K) during the dosing period, n represents an index which can be set, for example, to a value of 1.2, T_crIndicating a reference charge air coolant temperature (in K, e.g. T)_cr＝298K)，T_cxRepresenting the charge air coolant temperature (in K) during the measurement, s represents an index, η, which may be set to, for example, 1_mekRepresenting the mechanical efficiency of the engine 106, M representing the measured fuel quantity (in kg), S representing time (in S), MLS representing the flow of clean leakage fuel in the fuel pump (in kg/h), P representing engine power (in kW), LHV_testThe resulting LHV (MJ/kg), LHV are shown_ISOIndicates LHV (MJ/kg) according to ISO, EDP indicates fuel consumption (g/kWh) of the engine-driven pump, Be indicates fuel consumption (in g/kWh) on the test bench without correction according to the actual energy content of the fuel, and BISO indicates engine efficiency (in g/kWh) corrected according to ISO.

Another example of using the derived heating value in the control entity 110 includes estimating a fuel quality and/or estimating an efficiency of the engine 106 based at least in part on the derived heating value. The quality estimation may involve quality monitoring, for example, to compare the derived thermal value to a predefined threshold and issue a warning message or other kind of warning indication in response to the derived thermal value failing to exceed the threshold. For example, the warning indication may be provided as an audible indication and/or a visual indication via a user interface coupled to the control entity 110.

Another example of using the derived heating value in the control entity 110 includes adjusting operation of the engine 106 and/or adjusting a characteristic of fuel supplied to the engine 106 based at least in part on the derived heating value. As a variation of this use, the control entity 110 may be arranged to display an indication of the derived heating value via a user interface coupled to the control entity 110, so that an operator in charge of the engine 106 can adjust the operation of the engine 106 and/or adjust the properties of the fuel supplied to the engine 106 based at least in part on the displayed heating value. Yet another variation of this use of the derived heating value involves using another metric derived from the heating value (e.g., the SFOC described above) as a basis for adjusting the operation of the engine 106 and/or the fuel supplied to the engine 106.

In general, the control entity 110 may be arranged to continuously perform the method 200. In this regard, continuously performing the method 200 may include, for example, performing the method 200 at predefined time intervals, for example, to enable monitoring of changes in thermal values, such as changes in values derived from the thermal value (e.g., SFOC), observing changes in fuel quality, etc., and/or enabling continuous adjustment of operation of the engine 106 or fuel supplied to the engine 106 based at least in part on the derived thermal value.

The framework schematically shown in the example of fig. 1 may include a number of additional entities arranged in the fuel supply line 102 between the fuel tank 104 and the engine 106. As an example of this, there may be one or more entities arranged to adjust the viscosity of the fuel suitable for supply to the engine 106, e.g. by heating or cooling the fuel, pumping the fuel from the fuel tank 104 to the engine 106 via the fuel supply line 102, managing the (sufficient) fuel pressure in the fuel supply line 102 and/or managing the circulation of the fuel.

Although the example shown in fig. 1 relates to an example in which the fuel supply line 102 is used only to feed the engine 106, in other examples, the fuel supply line 102 may alternatively be applied to feed a device of two or more engines. In this scenario, one or more parameters describing observed fuel quality (e.g., a heating value such as LHV) derived in the control entity 110 based on fuel flow characteristics indicated in one or more measurement signals received from the fuel flow measurement assembly 108 are used to indicate characteristics of the fuel supplied to the two or more engines. In other examples, the fuel supply system for two or more engines may be operated such that one of the two or more engines is provided with excess fuel, for example about three to five times the actual amount of combustion in the engine, and fuel not combusted by the engine is circulated back to a so-called de-aeration tank (or mixing tank) where it is mixed with new fuel pumped from the fuel tank 102 (before supplying the new fuel back to the engine). In such an arrangement, the fuel flow measurement assembly 108 is arranged to measure the fuel temperature and fuel density of the fuel actually combusted in the engine. In one example, to enable fuel flow characteristics of individual engines to be observed in such an arrangement, the fuel flow measurement assembly 108 may include a first subassembly for measuring fuel flow to the engine and a second subassembly for measuring fuel flow recirculated back from the engine. Thus, the difference in fuel flow characteristics measured by the first and second subassemblies enables an inference of the actual amount of fuel combusted by the engine, thereby enabling, for example, a reliable estimate of fuel consumption, such as via an estimate of heating value according to the method 200 described previously.

The method 200 described in the foregoing may be implemented by hardware means, software means or a combination of hardware means and software means. As an example of this, fig. 4 schematically depicts some components of an apparatus 400 that may be used to implement the control entity 110 and cause the control entity 110 to perform the method 200 described hereinbefore. The apparatus 400 includes a processor 410 and a memory 420. Memory 420 may store data and computer program code 425. The apparatus 400 may also include a communication device 430 for wired or wireless communication with other devices, and/or a user I/O (input/output) component 440 arranged, together with the processor 410 and a portion of the computer program code 425, to provide a user interface for receiving input from a user and/or providing output to a user. In particular, the user I/O components may include user input devices such as one or more keys or buttons, a keyboard, a touch screen or pad, or the like. The user I/O components may include an output device such as a display or touch screen. The components of device 400 are communicatively coupled to each other via a bus 450, bus 450 being capable of transmitting data and control information between the components.

The memory 420 and a portion of the computer program code 425 stored in the memory 420 may also be arranged to, with the processor 410, cause the apparatus 400 to perform the method 200 described in the foregoing. The processor 410 is configured to read from and write to the memory 420. Although the processor 410 is described as a respective single component, it may be implemented as a respective one or more separate processing components. Similarly, while memory 420 is depicted as a respective single component, it may be implemented as respective one or more separate components, some or all of which may be integrated/removable, and/or may provide permanent/semi-permanent/dynamic/cached storage.

The computer program code 425 may comprise computer executable instructions which, when loaded into the processor 410, implement functions corresponding to the steps of the method 200 described hereinbefore. As one example, the computer program code 425 may include a computer program consisting of one or more sequences of one or more instructions. Processor 410 is capable of loading and executing a computer program by reading one or more sequences of one or more instructions contained therein from memory 420. One or more sequences of one or more instructions may be configured to, when executed by the processor 410, cause the apparatus 400 to perform the method 200 described in the foregoing. Accordingly, the apparatus 400 may comprise at least one processor 410 and at least one memory 420, the at least one memory 420 comprising computer program code 425 for one or more programs, the at least one memory 420 and the computer program code 425 configured to, with the at least one processor 410, cause the apparatus 400 to perform the method 200 as described hereinbefore.

Computer program code 425 may be provided, for example a computer program product comprising a computer readable non-transitory medium having stored thereon at least one computer program code 425, which when executed by the processor 410 causes the apparatus 400 to perform the method 200 as described hereinbefore. The computer-readable non-transitory medium may include a storage device or a recording medium, such as a CD-ROM, a DVD, a blu-ray disc, or another article of manufacture that tangibly embodies a computer program. As another example, the computer program may be provided as a signal configured to reliably transfer the computer program.

References herein to a processor should not be construed as including only a programmable processor but also to include special purpose circuits such as a Field Programmable Gate Array (FPGA), application specific circuit (ASIC), signal processor, etc. Features described in the foregoing description may be used in different combinations than those explicitly described.

Features described in the preceding description may be used in combinations other than the combinations explicitly described. Although functions have been described with reference to certain features, those functions may be performed by other features (whether described or not). Although features have been described with reference to certain embodiments, those features may also be present in other embodiments (whether described or not).