Non-invasive process fluid flow indication using temperature difference

Abstract

The process fluid flow system includes a first pipe skin sensor and a second pipe skin sensor. The first pipe skin sensor is arranged to measure the external temperature of the process fluid conduit at a first location on the process fluid conduit. The second pipe skin sensor is arranged to measure the external temperature of the process fluid conduit at a second location on the process fluid conduit. A measurement circuit is coupled to the first pipe skin sensor and the second pipe skin sensor. A controller is coupled to the measurement circuit and is configured to identify a process fluid flow condition based on signals from the first pipe skin sensor and the second pipe skin sensor, and output an indication of the process fluid flow condition.

Description

Technical Field

[0001] The present disclosure relates to a process fluid flow system. Background Art

[0002] Many industrial processes convey process fluids through pipes or other conduits. Such process fluids can include liquids, gases, and sometimes entrained solids. These process fluid flows can be found in a variety of industries, including but not limited to sanitary food and beverage production, water treatment, high-purity pharmaceuticals, chemical processing, hydrocarbon fuel industries, including hydrocarbon extraction and processing, and hydraulic fracturing techniques using abrasive and corrosive slurries.

[0003] Measuring process fluid properties (e.g., pressure, flow rate, or temperature) typically requires the use of a measuring instrument that extends into the process fluid. This extension of the measuring instrument into the process fluid is an invasive measurement because it requires the process fluid conduit to have a hole through which the measuring instrument passes. In addition, the hole must be sealed so that the process fluid does not leak or otherwise escape. Furthermore, the measuring instrument exposed to the process fluid may be worn or damaged by the high-speed process fluid, which in some cases may be highly abrasive. Summary of the Invention

[0004] A process fluid flow system includes a first pipe skin sensor and a second pipe skin sensor. The first pipe skin sensor is configured to measure an external temperature of a process fluid conduit at a first location on the process fluid conduit. The second pipe skin sensor is configured to measure an external temperature of the process fluid conduit at a second location on the process fluid conduit. A measurement circuit is coupled to the first pipe skin sensor and the second pipe skin sensor. A controller is coupled to the measurement circuit and is configured to identify a process fluid flow condition based on signals from the first pipe skin sensor and the second pipe skin sensor and output an indication of the process fluid flow condition. Brief Description of the Drawings

[0005] Figure 1 is a schematic diagram of a heat flow measurement system to which an embodiment of the present invention is particularly applicable.

[0006] Figure 2 is a schematic diagram of a process fluid temperature estimation system to which an embodiment of the present invention is particularly applicable.

[0007] Figure 3 is a schematic diagram of a process fluid temperature estimation system according to an embodiment of the present invention.

[0008] Figure 4 is a graph showing the variation of the temperature at different pipe wall positions over time as the process fluid flow changes.

[0009] Figure 5Block diagram of a method for estimating the process fluid temperature in a fluid conduit under various flow conditions according to an embodiment of the present invention. Detailed Description

[0010] Embodiments disclosed herein generally provide important process fluid information without the need for measuring instruments or sensors to penetrate the process fluid conduit. Thus, the embodiments described herein are generally considered non-invasive as they do not disrupt the process. However, based on multiple temperature measurements on the outer surface of the process fluid conduit, important process fluid parameters can be determined and provided. Examples include indications of whether the process fluid is flowing in the conduit and to some extent the flow conditions within the process fluid conduit. Additionally, this process fluid flow information can be provided to heat flow calculations or other suitable calculations to provide an estimate of the process fluid temperature within the conduit, which is adjusted or otherwise compensated for the determined process fluid flow. Although much of the description provided below will focus on this synergy, it is explicitly contemplated that the embodiments described herein can be implemented simply by providing an indication of the process fluid flow based on multiple external temperature measurements.

[0011] Typically, a temperature sensor is placed inside a thermowell and then inserted into the process fluid flow through a hole in the conduit. However, as noted above, this method may not always be practical. Additionally, thermowells typically require threaded ports or other robust mechanical mounts / seals in the conduit and thus must be designed for a process fluid flow system at a defined location. Thus, although thermowells can be used to provide accurate process fluid temperature, they have many limitations.

[0012] Recently, the process fluid temperature has been estimated by measuring the external temperature of a process fluid conduit (e.g., a pipe) and employing heat flow calculations. This external method is considered non-invasive as it does not require any holes or ports to be defined in the conduit. Thus, this non-invasive method can actually be deployed at any location along the conduit.

[0013] As noted above, the process fluid temperature can be estimated by measuring the external temperature of a process fluid conduit (e.g., a pipe) and employing heat flow calculations. Such a system typically uses the pipe skin (outer surface) temperature T skin and a reference temperature T referenceand a thermal resistance value (relative to the pipe wall and the thermal relationship between the position of the pipe skin and the reference temperature measurement position) to infer or otherwise estimate the process fluid temperature in the conduit. As the process fluid temperature changes (e.g., rises or falls), the temperature profile of the system will change. This temperature difference between the pipe skin temperature and the reference temperature is the result of heat flow between the two positions. Combining the knowledge of the thermal resistance (or other similar constants related to heat flow) between the two positions, the temperature of the inner surface of the process fluid conduit can be estimated. Since the inner surface of the process fluid conduit is in direct contact with the process fluid, this inner surface temperature can be used to estimate the temperature of the process fluid.

[0014] The process fluid temperature estimation described above is generally based on the assumption that the temperature of the inner surface of the conduit indicates the entire cross-section of the process fluid flowing through the conduit. Although this assumption is usually accurate for turbulent process fluids flowing through a filled conduit, it is not as accurate in some process fluid flow conditions. For example, if the process fluid flow is laminar or partially turbulent, this assumption is incorrect and may reduce the accuracy of the process fluid temperature estimation. In addition, if the process fluid conduit is not completely filled, or if the process fluid does not flow through the conduit, the temperature estimation accuracy will also be affected.

[0015] Figure 1 is a schematic diagram of a process fluid temperature estimation system to which an embodiment of the present invention is particularly applicable. As shown, the system 200 generally includes a pipe clamp portion 202 configured to clamp around a conduit or pipe 100. The pipe clamp 202 may have one or more lugs 204 to allow the clamp portion 202 to be positioned and clamped onto the pipe 100. The pipe clamp 202 may replace one of the lugs 204 with a hinge portion such that the pipe clamp 202 can be opened to be positioned on the pipe and then closed and fixed by the lugs 204. Although reference is made to Figure 1 the shown clamp is particularly useful, any suitable mechanical means for firmly positioning the system 200 around the outer surface of the pipe can be used according to the embodiments described herein.

[0016] System 200 includes a heat flux sensor capsule 206 or a suitable surface sensor that is pressed against the outer diameter 116 of the conduit 100 by a spring 208. The term "capsule" is not intended to denote any particular structure or shape and can thus be formed in a variety of shapes, sizes, and configurations. Although a spring 208 is shown, those skilled in the art will understand that a variety of techniques can be used to urge the sensor capsule 206 into continuous contact with the outer diameter 116. The sensor capsule 206 typically includes one or more temperature sensitive elements, e.g., a resistance temperature device (RTD) or a thermocouple. The sensors within the capsule 206 are electrically connected to a transmitter circuit within the housing 210 that is configured to obtain one or more temperature measurements from the sensor capsule 206 and calculate an estimate of the process fluid temperature based on the measurements from the sensor capsule 206 and a reference temperature (e.g., the temperature measured within the housing 210), or otherwise provide to the circuitry within the housing 210.

[0017] In one example, the basic heat flux calculation can be simplified to:

[0018] T corrected = T skin +(T skin - T reference )*(R pipe / R sensor ).

[0019] In this equation, T skin is the measured temperature of the outer surface of the conduit. Additionally, T reference is a second temperature obtained relative to the location of the temperature sensor that is thermally resistant (R skin ) from the measurement of T sensor . T reference is typically sensed by a dedicated temperature sensor within the housing 210. However, T reference can also be sensed or inferred in other ways. For example, a temperature sensor can be placed external to the transmitter to replace the terminal temperature measurement in the heat transfer calculation. This external sensor will measure the temperature of the environment around the transmitter. As another example, industrial electronic devices typically have on-board temperature measurement capabilities. The electronic device temperature measurement can be used to replace the terminal temperature in the heat transfer calculation. As another example, if the thermal conductivity of the system is known and the ambient temperature around the transmitter is fixed or user controlled, the fixed or user controllable temperature can be used as the reference temperature.

[0020] R pipe is the thermal resistance of the conduit and can be obtained manually by obtaining conduit material information, wall thickness information, etc. Additionally or alternatively, R pipeassociated parameters, or calculate and store the parameter for subsequent use. Thus, using the appropriate heat flux calculation as described above, the circuitry within housing 210 is capable of calculating an estimated value of the process fluid temperature (T corrected ), and transmitting an indication of such process fluid temperature to a suitable device and / or control room. In the Figure 1 example shown, such information can be transmitted wirelessly via antenna 212.

[0021] Figure 2 is a circuit block diagram of the circuitry within housing 210 of a heat flux measurement system 200 to which embodiments of the present invention are particularly applicable. System 200 includes a communication circuit 220 coupled to a controller 222. Communication circuit 220 can be any suitable circuitry capable of transmitting information regarding the estimated process fluid temperature. Communication circuit 220 allows heat flux measurement system 200 to transmit a process fluid temperature output on a process communication loop or segment. Suitable examples of process communication loop protocols include the 4 - 20 mA protocol, Highway Addressable Remote Sensor protocol, FOUNDATION TM Fieldbus protocol, and the WirelessHART protocol (IEC 62591).

[0022] Heat flux measurement system 200 also includes a power module 224 that provides power to all components of system 200, as indicated by arrow 226. In embodiments where heat flux measurement system 200 is coupled to a wired process communication loop such as a loop or FOUNDATION TM Fieldbus segment, power module 224 can include suitable circuitry for conditioning the power received from the loop or segment to operate the various components of system 200. Thus, in such wired process communication loop embodiments, power module 224 can provide suitable power conditioning to allow the entire device to be powered by the loop to which it is coupled. In other embodiments, when using wireless process communication, power module 224 can include a power source, e.g., a battery, and suitable conditioning circuitry.

[0023] Controller 222 includes any suitable means capable of generating a heat - flux - based estimated process fluid temperature using measurements from sensors within bladder 206 and additional reference temperatures such as the terminal temperature within housing 210. In one example, controller 222 is a microprocessor. Controller 222 is communicatively coupled to communication circuit 220.

[0024] The measurement circuit 228 is coupled to the controller 222 and provides digital indications of measurements obtained from the one or more temperature sensors 230. The measurement circuit 228 may include one or more analog-to-digital converters and / or suitable multiplexing circuits to interface the one or more analog-to-digital converters to the temperature sensors 230. In addition, the measurement circuit 228 may include suitable amplification and / or linearization circuits as appropriate for the various types of temperature sensors employed.

[0025] The temperature sensor 230 illustratively includes a terminal temperature sensor 232, an electronic device temperature sensor 234, and may also include other items, as shown in box 236. The electronic device temperature sensor 234 is coupled to the electronic circuit of the system 200 and is used to determine the temperature of the electronic device. Typically, the electronic device temperature sensor 234 is used to protect the electronic circuit from overheating. For example, when the electronic device reaches a certain temperature, a fan will be turned on to reduce the temperature. In one embodiment, the electronic device temperature sensor 234 senses a reference temperature.

[0026] Figure 3 300 is a schematic diagram of a process fluid temperature estimation system according to an embodiment of the present invention. Figure 1 ) have some similarities, and similar components are numbered similarly. Specifically, system 300 includes a sensor capsule 306, which is urged into contact with the outer surface of pipe 100 via a spring or other suitable mechanical element 308. In addition, sensor capsule 306 is electrically coupled to electronics within housing 310 to generate process fluid estimates. However, as Figure 3 As shown, three additional temperature sensor capsules 320, 322, and 324 are located at different radial locations around the pipe 100 and are coupled thereto by the fixture 302. In the example shown, the four sensor capsules (306, 320, 322, and 324) are arranged at approximately 90° intervals. Thus, the temperature sensor capsule 306 is positioned on the top surface of the pipe 100, while the temperature sensor capsule 324 is positioned on the bottom surface of the pipe 100. Similarly, the sensor capsule 320 is positioned on one side of the pipe 100, while the sensor capsule 322 is positioned substantially diametrically opposite the sensor capsule 320. Each sensor capsule is electrically coupled to the measurement circuitry within the transmitter housing 310 via a corresponding connector (e.g., connectors 326, 328, and 330) using either wired communication (not shown) or wireless communication. It will be appreciated that each sensor capsule measures the pipe skin temperature at its respective location and can be used to generate a temperature estimate of the inner surface of the pipe 100 corresponding to the mounting location of the respective sensor capsule. The controller 222 of the electronics disposed within the transmitter housing 310 is programmed or otherwise configured to determine process fluid flow conditions based on the differences between the various estimates of the internal surface temperature at different locations.Figure 1 and Figure 2 As shown in Figure 2 , the reference temperature indication can be provided by a reference temperature sensor disposed within the transmitter housing 310, or can be transmitted via process communication (e.g., via antenna 312) or by coupling to an additional temperature sensor. In one embodiment, the temperature sensor is disposed within the transmitter housing 310 near the terminal connection and is coupled to the measurement circuit 228.

[0027] By placing two or more sensor pods at different locations around the pipe or conduit 100, the system 300 can determine whether the process fluid is flowing properly to accurately estimate the temperature of the process fluid to be provided. Additionally, the embodiments described herein can also determine whether the process fluid conduit 100 is only partially filled and / or whether the process fluid is flowing through the process fluid conduit 100. These additional indications can be provided locally by the system 300 (e.g., via a local display), or they can be transmitted to a remote device via process communication, e.g., via antenna 312.

[0028] In some embodiments, it is very important to know the installation orientation of the various sensor pods before determining what the sensor characteristics mean. In other words, the controller 222 within the transmitter housing 310 must know that the sensor pod 306 is disposed at the top of the process fluid conduit 100, and must know that the sensor pod 324 is disposed on the bottom side of the process fluid conduit 100. Similarly, the controller must also know that the sensor pods 320 and 322 are disposed on opposite sides of the process fluid conduit. Using this information, the controller 222 can generate indications and / or make corrections for changing process fluid flow conditions to provide a more accurate estimate of the process fluid temperature. The following are examples of flow conditions and how the controller 222 can identify them.

[0029] If the gradient across the process fluid produces the highest temperature at the top sensor and the lowest temperature at the bottom temperature sensor, and the two side sensors provide substantially the same indication, then the controller 222 can determine that no process fluid is flowing through the process fluid conduit 100. This is because the process fluid contacts all the inner surfaces of the process fluid conduit, and since the fluid is not flowing, the hotter fluid will move to the top of the process fluid conduit while the colder fluid will remain at the bottom. When this occurs, the controller 222 can provide an indication of no flow condition with respect to the process fluid. Additionally, an average value of the process fluid temperature can be provided by averaging the top sensor and the bottom sensor and comparing this estimate with the estimates provided by the two side sensors. In this example, the controller 222 can provide an estimate of the process fluid temperature and an additional indication of no flow of the process fluid.

[0030] If both the bottom sensor and the side sensor provide nearly equal temperatures, but the top sensor (sensor bladder 306) is at a temperature between the ambient environment and the values of the side and bottom sensors, the controller 222 may indicate that the process fluid conduit is filled with more than 50%. Additionally, when this occurs, the controller 222 may provide an estimate of the process fluid temperature based only on the values of the side sensor bladder and the bottom sensor bladder, and may additionally provide an indication that the conduit is filled with more than 50% but less than 100%.

[0031] If the measured temperatures of the top sensor and the side sensor are between the ambient temperature and the temperature of the bottom sensor, but the value of the top sensor is closest to the ambient temperature, the controller 222 may indicate that the process fluid conduit is filled less than 50% full. Additionally, an indication of the process fluid temperature may be provided based only on the temperature from the bottom sensor bladder 324, and the controller 222 may provide an indication that the conduit 100 is filled less than 50% full.

[0032] If the top sensor and the side sensor are at substantially the same temperature, but the bottom sensor bladder 324 records a different value, the controller 222 may determine that there is some material on the inner surface at the bottom of the process fluid conduit. Examples of such materials may include moisture, sediment, etc. In such a case, an estimate of the process fluid temperature may be provided based only on the top sensor and the side sensor, and the controller 222 may provide an additional indication that material has been detected in the inner surface at the bottom of the conduit 100.

[0033] Figure 4 is a graph showing the temperature change over time at different pipe wall positions as the process fluid flow changes. Figure 4 The data shown in illustrates the condition when the process fluid is not flowing. The data shows the difference between the side-mounted sensor (shown by reference numeral 400) and the data from the bottom-mounted sensor (shown by reference numeral 402). At time t1, the pump starts working to start generating the process fluid flow. It can be seen that the sensors are subject to similar temperature measurements, and their values converge rapidly at time t2.

[0034] Although with reference to Figure 3 the illustrated embodiments show a plurality of sensor bladders coupled to the clamping mechanism, and each sensor bladder is coupled to a corresponding connector, it can be clearly envisioned that in other embodiments, a plurality of sensor points may be directly built into the clamping mechanism, and various sensor wires may be wired into the transmitter housing 310 and directly coupled to the measurement circuit 228. Additionally, although with reference to Figure 3The illustrated embodiment uses a total of four sensor pods, but it is also envisioned that some process fluid change information can be discerned by using three such sensor pods (a top sensor pod, a bottom sensor pod, and a side sensor pod). Additionally, it is explicitly envisioned that additional information can be discerned by using more than four sensor pods. Further, it is explicitly envisioned that multiple such systems 300 can be located at different longitudinal positions along the process fluid conduit, and one or both controllers within each system can be provided with additional information from another process fluid estimation system such that temperature flow variations along the flow direction can be analyzed to determine additional process fluid flow conditions and / or corrections within the process fluid estimation system. For example, such information can indicate whether the process fluid flow is turbulent, laminar, or transitional. Cross-sectional gradients can also be used to detect disturbances to turbulent conditions and to indicate whether the flow is fully developed. Pipe breaks such as elbows, valves, or reducers can disrupt fully developed turbulence. Accurate temperature measurements (and flow measurements) typically depend on fully developed flow conditions.

[0035] In embodiments employing additional temperature measurements on the outer surface of the process fluid conduit, the linearity of the cross-sectional temperature can be determined. This linearity indication can assist in detecting conditions such as fouling, thinning, presence of deposits, or excess water in steam applications, and can even provide an indication to take action. This is important because in some cases, if no action is taken, it can lead to efficiency impacts, pressure buildup, or even permanent damage to the process fluid conduit.

[0036] In some cases, the steady-state temperature difference may be all that is required to determine a viable state, but by monitoring the timing information due to temperature variations, a better understanding of the degree of fouling or thinning can be obtained. Thus, the various process fluid estimations provided by system 300 can be stored by an external device or stored internally and analyzed over time to identify trends indicating wear or other deterioration within the system.

[0037] Although the embodiments described so far have generally envisioned the use of sensor pods with resistance temperature devices (RTDs) within the sensor pods, any suitable temperature sensing structure or technique can be used according to embodiments of the present invention. For example, sensor methods such as optical fibers can provide a technique to provide a higher density of temperature measurement points around conduit 100.

[0038] Figure 5 is a block diagram of a method for estimating the temperature of a process fluid within a fluid conduit under various flow conditions according to an embodiment of the present invention. Method 500 begins at block 502, where the skin temperature is measured at multiple locations around the process fluid conduit. For example, as referred to above Figure 3As described above, the skin temperature can be measured at the top, bottom, and side positions. Next, at block 504, any differences between the various temperature measurements are analyzed to identify a specific flow condition. Examples of flow conditions and the differences in the measured temperatures generated by such flow conditions have been described above. It is also explicitly contemplated that the degree of required measurement difference (or equality) can be set to a user-selected threshold or can be programmatically input by the manufacturer during the assembly or construction of the process fluid temperature estimation system. Examples of various conditions that can be identified based on the difference in measured temperatures include: a process fluid conduit that is 100% full and flowing, as shown by reference numeral 506; and a no-flow condition as shown by reference numeral 508; a flow condition that is greater than 50% filled, as shown by reference numeral 510; a flow condition that is less than 50% filled, as shown by reference numeral 512, and the presence of material on the inner surface of the bottom of the process fluid conduit, as shown by reference numeral 514. It will be appreciated that if additional sensor pods are provided around the process fluid conduit (e.g., spaced at 45° intervals), additional process fluid conduit fill levels (e.g., 25% and 75%) can also be provided. Next, at block 516, the process fluid flow condition can be provided as an output and / or can be used to adjust or otherwise compensate for the process fluid temperature estimation. As described above, in some cases, the process fluid temperature estimation can be based on data from fewer sensors than all available sensors. For example, if the process conduit is less than 50% filled, the process fluid estimation will be based only on the skin temperature sensed by the bottom sensor pod ( Figure 3 shown as 324 in). Conversely, if the process fluid flow condition indicates that material (e.g., sediment) is disposed adjacent to the bottom surface of the process fluid conduit 100 but the process fluid conduit is full, the process fluid temperature estimation will be based on the measurements from the top and side sensor pods and the value received from the bottom sensor pod will be ignored. Thus, an adjusted process fluid temperature estimation is provided based on the identified process fluid flow condition. Next, at block 518, the system can optionally report the identified process fluid flow condition.

[0039] Although the invention has been described with reference to the preferred embodiments, those skilled in the art will recognize that modifications can be made in form and detail without departing from the spirit and scope of the invention.

Claims

1. A process fluid flow system, comprising: A first pipe skin sensor configured to measure an external temperature of the process fluid conduit at a first location on the process fluid conduit; A second pipe skin sensor configured to measure an external temperature of the process fluid conduit at a second location on the process fluid conduit; A measurement circuit coupled to the first pipe skin sensor and the second pipe skin sensor to obtain surface temperature measurements at the first and second locations; And A controller coupled to the measurement circuit and configured to identify a process fluid flow condition based on signals from the first pipe skin sensor and the second pipe skin sensor, select a combination of surface temperature measurements based on the identified process fluid flow condition, apply a heat flux calculation to the selected combination of surface temperature measurements to generate a process fluid temperature estimate, and provide the process fluid temperature estimate as an output.

2. The process fluid flow system according to claim 1, further comprising a fixture configured to mount the first pipe skin sensor and the second pipe skin sensor on substantially opposite sides of the process fluid conduit.

3. The process fluid flow system according to claim 2, further comprising a third pipe skin sensor mounted to the fixture between the first pipe skin sensor and the second pipe skin sensor.

4. The process fluid flow system according to claim 3, further comprising a fourth pipe skin sensor mounted to the fixture and radially opposite the third pipe skin sensor.

5. The process fluid flow system according to claim 4, wherein, The first pipe skin sensor, the second pipe skin sensor, the third pipe skin sensor, and the fourth pipe skin sensor are spaced approximately 90 degrees around an outer surface of the process fluid conduit.

6. The process fluid flow system according to claim 5, wherein, The process fluid flow condition is selected from the group consisting of: a full process fluid conduit with process fluid flowing therethrough; A full process fluid conduit without process fluid flow; a process fluid conduit greater than 50% full with process fluid flowing therethrough; a process fluid conduit less than 50% full with process fluid flowing therethrough.

7. The process fluid flow system according to claim 5, wherein, The process fluid flow condition indicates a material disposed on a bottom surface of the process fluid conduit.

8. The process fluid flow system according to claim 1, wherein, The controller is configured to obtain a reference temperature measurement having a fixed thermal relationship relative to the first pipe skin sensor and the second pipe skin sensor, the reference temperature measurement being different from the measured external temperature of the process fluid conduit, and wherein the controller is configured to use a process fluid flow output and a heat flux calculation to provide a process fluid temperature estimate output adjusted based on the process fluid flow output.

9. The process fluid flow system according to claim 8, wherein, Based on the process fluid flow condition, a process fluid temperature estimate is generated using fewer sensors than all first and second sensors.

10. The process fluid flow system according to claim 8 further includes a communication circuit coupled to the controller, and wherein, The process fluid temperature estimate is transmitted to a remote device.

11. The process fluid flow system according to claim 10, wherein, The controller is configured to transmit the identified process fluid flow condition to the remote device.

12. The process fluid flow system according to claim 1, wherein, The process fluid flow condition is a fully filled process fluid conduit through which a process fluid flows.

13. The process fluid flow system according to claim 1, wherein, The process fluid flow condition is a fully filled process fluid conduit without a process fluid flow.

14. The process fluid flow system according to claim 1, wherein, The process fluid flow condition is a process fluid conduit that is more than 50% filled with a process fluid flowing therethrough.

15. The process fluid flow system according to claim 1, wherein, The process fluid flow condition is a process fluid conduit that is less than 50% filled with a process fluid flowing therethrough.

16. The process fluid flow system according to claim 1, wherein, The process fluid flow condition indicates a material disposed on the bottom surface of the process fluid conduit.

17. A method for estimating process fluid flow characteristics within a fluid conduit, the method comprising: Obtaining surface temperature measurements at a plurality of locations near the outer diameter of the fluid conduit; Analyzing the plurality of surface temperature measurements to identify a flow condition within the fluid conduit; Selecting a combination of surface temperature measurements based on the identified flow condition; Applying a heat flux calculation to the selected combination of surface temperature measurements to generate a process fluid temperature estimate; And Providing the process fluid temperature estimate as an output.

18. The method according to claim 17, wherein, Analyzing the plurality of surface temperature measurements includes determining whether a difference between the surface temperature measurements exceeds a predetermined threshold indicative of one of various flow conditions.

19. The method according to claim 18, wherein The predetermined threshold is provided by a user.

20. The method according to claim 17, further comprising generating an indication of the identified flow condition.

21. The method according to claim 20, wherein, The indication is provided as a local output.

22. The method according to claim 20, wherein, The indication is selected from the group consisting of laminar flow, transitional flow, and turbulent flow.

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