Sensor system for measuring and controlling heater system performance and integrated heater-sensor

Abstract

An integrated heater device and heater system for heating a fluid, the integrated heater device comprising: a multi-part resistive element configured to measure one or more performance characteristics of the fluid, the multi-part resistive element having a first part defined by a first electrically conductive material and a second part defined by a second electrically conductive material, the second electrically conductive material having a lower temperature coefficient of resistance (TCR) than the first electrically conductive material, wherein the multi-part resistive element is operable as a heater to generate heat and as a sensor, and the first part of the multi-part resistive element is configured to extend along a designated area to measure a first performance characteristic of the fluid.

Description

[0001] Related Applications

[0002] This case is a divisional application of the invention patent application entitled Sensor system for measuring and controlling heater system performance and integrated heater-sensor, application number 201880059920.7. TECHNICAL FIELD

[0003] The present invention relates to a sensor for measuring a characteristic of a heater system. BACKGROUND

[0004] The statements in this section merely provide background information related to the present disclosure and do not constitute prior art.

[0005] A heating system, such as a fluid heating system, typically includes a heater operable to heat an object (e.g., a wafer, a liquid, a gas, etc.) and a control system for controlling the heater. Multiple independent sensors are typically used to measure different performance characteristics of the heating system. For example, a fluid heating system, such as an electric fryer, can use multiple sensor devices to measure fluid temperature, ambient temperature, fluid mass, liquid level, etc. The control system receives data from the sensor devices to obtain the performance characteristics and ultimately determine an appropriate amount of power to apply to the heater.

[0006] With multiple sensor devices, the heater system becomes quite complex and can only be able to detect large incremental changes. The present disclosure addresses these and other issues. SUMMARY

[0007] This section provides a general summary of the disclosure, and not a comprehensive disclosure of its full scope or all of its features.

[0008] In one form, the present disclosure relates to a fluid sensor system for a heating system. The sensor system includes a probe having a finite length, a portion of the probe being immersed in a fluid. The probe includes a resistive heating element and a fluid temperature sensor for measuring one or more performance characteristics. The fluid temperature sensor is configured to measure a fluid temperature, the resistive heating element is operable as a heater to create a temperature differential along the length of the probe to detect the fluid, and is operable as a sensor to measure a liquid level.

[0009] In another form, the fluid sensor system further includes a control system configured to operate the probe and determine one or more performance characteristics of the heating system based on at least one of an electrical response of the resistive heating element operating as a sensor and an electrical response of the fluid temperature sensor. The performance characteristics include at least one of a liquid level and a fluid temperature.

[0010] In yet another form, the control system is configured to determine the liquid level based on the fluid temperature, the electrical resistance of the electrical resistance heating element, and predetermined information associating a given electrical resistance and a given temperature with a liquid level.

[0011] In one form, the control system is configured to apply a first amount of power to the electrical resistance heating element to create a temperature differential when the fluid temperature is substantially the same as the ambient temperature, and to apply a second amount of power less than the first amount of power to measure the electrical resistance of the electrical resistance heating element when the fluid temperature is different than the ambient temperature.

[0012] In another form, the probe further includes an ambient temperature sensor to measure the ambient temperature, wherein the ambient temperature sensor is disposed at a portion of the probe distal from the fluid.

[0013] In yet another form, the ambient temperature sensor is a thermocouple.

[0014] In one form, the probe further includes a resistance temperature detector (RTD), and at least one of the electrical resistance heating element and the fluid temperature sensor is connected to the RTD.

[0015] In another form, the probe further includes a four-wire resistance temperature detector (RTD). A first loop wire having a high temperature coefficient of resistance (TCR) is connected to the RTD to form the electrical resistance heating element, and a second loop wire is connected to the RTD to form the fluid temperature sensor.

[0016] In yet another form, the probe further includes a limit sensor to detect a maximum fluid temperature.

[0017] In one form, the fluid temperature sensor is a thermocouple.

[0018] In one form, the present disclosure is directed to a fluid sensor system for a heating system operable to heat a fluid. The sensor system includes a probe having a finite length with a portion of the probe immersed in the fluid, and a control system. The probe includes an electrical resistance heating element to detect the fluid and a fluid temperature sensor to measure a temperature of the fluid. The electrical resistance heating element is operable as a heater to create a temperature differential along the length of the probe to detect the fluid and is operable as a sensor to measure a liquid level. The control system is configured to determine one or more performance characteristics of the heating system based on at least one of an electrical response from the electrical resistance heating element operating as a sensor and an electrical response of the fluid temperature sensor and based on predetermined information. The control system is configured to operate the electrical resistance heating element as a heater in response to the fluid temperature being substantially the same as an ambient temperature.

[0019] In another form, the control system is configured to apply at least one of: when the fluid temperature is substantially the same as the ambient temperature, applying a first amount of power to the resistive heating element to generate a temperature differential; and when the fluid temperature is different than the ambient temperature, applying a second amount of power less than the first amount of power to the resistive heating element to measure the electrical resistance of the resistive heating element.

[0020] In yet another form, the control system is configured to determine the liquid level as a performance characteristic based on the fluid temperature, the electrical resistance of the resistive heating element, and predetermined information associating a given electrical resistance and a given fluid temperature with the liquid level.

[0021] In one form, the probe further includes an ambient temperature sensor to measure the ambient temperature.

[0022] In another form, the probe further includes a resistive temperature detector (RTD), and at least one of the resistive heating element and the fluid temperature sensor is connected to the RTD.

[0023] In yet another form, the probe further includes a limit sensor to detect a maximum fluid temperature, and the control system is configured to measure the fluid temperature based on an electrical response of the limit sensor, and determine whether the fluid temperature is above a predetermined limit.

[0024] In one form, the disclosure relates to a heater system having a sensor system, a heater operable to heat a fluid, and a heater control system in communication with the control system of the sensor system and configured to control the heater based on a performance characteristic.

[0025] In one form, the disclosure relates to an integrated heater device including at least one multi-part resistive element configured to measure one or more performance characteristics. The at least one multi-part resistive element has a first part defined by a first electrically conductive material and a second part defined by a second electrically conductive material having a lower temperature coefficient of resistance (TCR) than the first electrically conductive material. The multi-part resistive element is operable as a heater to generate heat and as a sensor, and the first part of the multi-part resistive element is configured to extend along a designated area to measure a first performance characteristic.

[0026] In another form, the multi-part resistive element includes a first member and a second member having a different Seebeck coefficient than the first member. The first member and the second member form a temperature sensing junction to measure a temperature at a first location as a second performance characteristic.

[0027] In yet another form, the present disclosure is directed to a heater system including an integrated heater device and a control system configured to operate the heater device, and more particularly, to operate a multi-part resistive element as a heater to heat an object or as a sensor to measure an electrical response of the multi-part resistive element.

[0028] Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. BRIEF DESCRIPTION OF DRAWINGS

[0029] So that the disclosure can be well understood, it will now be described by way of example only, with reference to various forms thereof as illustrated in the accompanying drawings in which:

[0030] Figure 1 is a schematic diagram of a fluid sensor system in accordance with the teachings of the present disclosure;

[0031] Figure 2 shows a functional relationship between resistance, temperature, and liquid level based on the teachings of the present disclosure;

[0032] Figure 3 is a graph depicting an example of a resistive response at different inputs;

[0033] Figure 4 is a block diagram of a control system of a fluid sensor system in accordance with the teachings of the present disclosure;

[0034] Figure 5 is a flowchart of a fluid monitoring routine performed by a fluid sensor system in accordance with the teachings of the present disclosure;

[0035] Figure 6A , Figure 6B , Figure 6C and Figure 6D shows a variation of a probe for a fluid sensor system in accordance with the teachings of the present disclosure;

[0036] Figures 7A-7J shows an additional configuration of a resistive heating element, a fluid temperature sensor, and / or an ambient temperature sensor of a probe for a fluid sensor system in accordance with the teachings of the present disclosure;

[0037] Figure 8 shows a heater system with an integrated heater-sensor in accordance with the teachings of the present disclosure;

[0038] Figure 9 is a partial cutaway view of an integrated heater-sensor of a first form in accordance with the teachings of the present disclosure;

[0039] Figure 10This is a partial cross-sectional view of an integrated heater-sensor of a second form according to the teachings of this disclosure;

[0040] Figure 11 This is a partial cross-sectional view of a third form of integrated heater-sensor according to the teachings of this disclosure; and

[0041] Figure 12 yes Figure 8 A block diagram of the heater control system for the heater system.

[0042] The accompanying drawings described herein are for illustrative purposes only and are not intended to limit the scope of this disclosure in any way. Detailed Implementation

[0043] The following description is exemplary in nature only and is not intended to limit this disclosure, its application, or its uses. It should be understood that in all the drawings, corresponding reference numerals denote the same or corresponding parts and features.

[0044] A heating system for heating, for example, a liquid, typically includes multiple independent sensors for measuring the fluid temperature and ambient temperature. In one form, the heating system includes a heater for heating a fluid such as oil or exhaust gas, and a heater control system for controlling the operation of the heater based on measurements from the sensors. In another form, this disclosure relates to a fluid sensor system for measuring multiple performance characteristics of a heater system. Performance characteristics may include, for example, liquid level, fluid temperature, ambient temperature, and / or other suitable information.

[0045] refer to Figure 1 and Figure 2 An example of a fluid sensor system 100 will now be described. In one form, the device 100 includes a probe 102 having a sheath 103 of finite length and a control system 104 electrically connected to the probe 102. The probe 102 is placed in a fluid 106 such that the probe 102 is partially below and partially above the fluid 106, and the control system 104 is configured to control the operation of the probe 102 to measure performance characteristics.

[0046] Probe 102 includes one or more sensors extending within a sheath 103. In one form, the sheath 103 is made of a protective metallic alloy, typically nickel and chromium, to prevent corrosion (e.g., stainless steel, INCOLOY, and INCONEL). In another form, for applications below approximately 260°C, sensors 120 and 124 may be insulated with plastic and include a heat-filled material or potting compound for improved performance. For applications above approximately 260°C, sensors 120 and 124 may be held in place and insulated with ceramic or ceramic powder, typically compacted MgO. Other suitable constructions for holding sensors 120 and 124, within the scope of this disclosure, may also be used. For example, sensing elements 120 and 124 may be made of wire, foil, or film and insulated with polyimide, plastic, ceramic, glass, or other insulating materials.

[0047] Probe 102 includes a fluid temperature sensor 120, an ambient temperature sensor 122, and a resistance heating element 124 for measuring performance characteristics, such as fluid temperature (T). FL ), ambient temperature (T) AMB The fluid temperature sensor 120 and the ambient temperature sensor 122 are provided as thermocouples (i.e., first thermocouple 120 and second thermocouple 122) for measuring the fluid temperature and ambient temperature, respectively. As thermocouples, each of thermocouples 120 and 122 includes two wires made of different materials, such as aluminum nickel and chromium nickel. Figure 1 (M1 and M2 in the model). The wires are joined together at one end to form junctions J1 and J2, respectively. For measuring fluid temperature, junction J1 is positioned along probe 102 to be immersed in fluid 106, and for measuring ambient temperature, junction J2 is positioned along probe 102 to be outside the fluid. The other ends of the wires of thermocouples 120 and 122 are electrically connected to control system 104 at terminals 1261, 1262 (collectively referred to as terminals 126) and 1281, 1282 (collectively referred to as terminals 128), respectively. The wires can be electrically connected to control system 104 in various suitable ways. For example, the wires can be connected via power pins, leads, directly to dedicated ports within control system 104, and / or via other suitable methods to dedicated ports within control system 104.

[0048] While specific examples of material types for thermocouples 120 and 122 are provided, other suitable materials with different Seebeck coefficients can be used. For example, nickel alloys, iron, constantan, etc., can be used. Various combinations thereof. Furthermore, the type of wire used for thermocouple 120 may differ from the type of wire used for thermocouple 122.

[0049] In operation, as junction Jl of thermocouple 120 experiences a temperature change, a voltage change is generated between terminals 126i and 1262and measured by control system 104. Based on the voltage and predetermined data (e.g., a reference table), control system 104 determines the temperature at junction Jl. Thermocouple 122 operates in a similar manner to thermocouple 120. Junction Jl of thermocouple 120 is immersed in fluid 106 to measure the temperature of fluid 106, and junction J2 of thermocouple 122 is located above fluid 106 to measure the ambient temperature. Hereinafter, thermocouple 120 can be referred to as a fluid thermocouple 120, and thermocouple 122 can be referred to as an ambient thermocouple 122.

[0050] Resistance heating element 124 is made of a material with a high temperature coefficient of resistance (TCR), such as nickel, and measures an average temperature along the length of probe 102. The resistance heating element can be provided as a wire, foil, and / or thin film. Resistance heating element 124 is simultaneously affected by both the ambient temperature and the fluid temperature, while thermocouples 120 and 122 are independently affected by both the ambient temperature and the fluid temperature. In particular, resistance heating element 124 can be configured as a "two-wire" heating element, such that it functions as both a heater and a temperature sensor. Resistance heating element 124 is connected to and operable by control system 102 through terminals 130i and 1302(collectively, terminals 130). For example, such two-wire capability is disclosed in U.S. Patent No. 7,196,295, which is commonly assigned with the present application and incorporated by reference herein in its entirety. Generally, an electrical characteristic or response (e.g., voltage / current) is measured at terminals 130i and 1302, and the electrical characteristic or response (e.g., voltage / current) is used to determine the resistance of resistance heating element 124. This resistance is then used to determine the fluid level. In particular, the resistance of resistance heating element 124 is a function of temperature and fluid level. For example, Figure 2 An example correlation between resistance detected by a high TCR loop and fluid (e.g., oil) level is shown, Figure 3 An expected resistance response for active fluid level sensing provided by a control system is shown. According to Figure 3 The resistance response is a function of air and oil temperature at each temperature that is proportional to the length of the sensing loop, according to the graph of

[0051] In one form, the total resistance detected by the resistive element is further defined in Equation 1, where "R1" represents the resistance above the fluid (e.g., along LI), "R2" represents the resistance around the fluid surface (e.g., along L2), and "R3" represents the resistance below the fluid (e.g., along L3). In one form, the liquid level (i.e., L2) can be determined using a predefined model that includes sensor material properties, sensor geometry, fluid properties, attachment methods, and even container material properties / geometry. Each of the resistances R1, R2, and R3 are defined in Equations 2, 3, and 4, respectively. As described below, R 总 by the control system 104.

[0052] Equation 1... R 总 = R1+ R2+ R3

[0053] Equation 2... R1= f(T AMB , LI)

[0054] Equation 3... R2= f(T AMB , T FL , L2)

[0055] Equation 4... R3= f(T FL + L3)

[0056] Referring to Figure 4 , the control system 104 is communicably connected to a heater control system 150 that operates a heater that heats the fluid of the heater system. The control system 104 transmits the measured performance characteristics to the heater control system 150, which controls the operation of the heater based on the characteristics. In one form, the control system 104 includes a power module 152, a probe control module 154, a temperature module 156, a liquid level module 158, and a communication module 160. In one form, the control system 104 includes a combination of electronics (e.g., microprocessor, memory, communication interface, voltage-to-current converter, voltage-current measurement circuit, etc.) and software programs / algorithms that are stored in the memory and executable by the microprocessor to perform the operations described herein.

[0057] The power module 152 is configured to power the electronics within the control system 104 and apply specified power limits to the probe 102 based on the desired operating state of the probe 102. For example, the power module 152 can include a power regulator circuit (e.g., voltage divider, voltage converter, etc.) to regulate power from a power source 164 and apply the regulated power to the probe 102.

[0058] The probe control module 154 is configured to select an operating state of the resistive heating element of the probe 102 and instruct the power module 152 to apply a specified power limit assigned for the selected state. More particularly, where the resistive heating element 124 is provided for dual line control, the element 124 operates as either a heater or a sensor. To operate as a sensor, the power module 152 applies a small amount of power (e.g., 0.1 mA current) to the resistive heating element 124 to measure the resistance of the resistive heating element 124. To operate as a heater, the power module 152 is configured to apply a heat generating stimulus power (e.g., 75 W, 100 W, and / or other suitable values based on system characteristics) to the resistive heating element 124. The heater state can be selected at the start of the heater system when the fluid temperature and the ambient temperature are substantially the same. Specifically, the fluid 106 has a different thermal diffusivity (ai) than air (a2, ai≠ a2). Thus, when the fluid temperature and the ambient temperature are equal, the resistive heating element 124 operates as a heater to create a temperature differential along the length of the probe 102 to detect the presence of the fluid. The heat generating stimulus power can be applied for a preset duration and / or until a temperature differential is created on the partially submerged probe 102. Once the fluid is detected, it is safe for the heater of the heater system to begin heating the fluid. More particularly, starting the heater of the heater system without fluid or with a small amount of fluid can damage the heater. Once a proper temperature gradient is detected along the length of the probe, the probe control module 154 can operate the resistive heating element 124 as a sensor.

[0059] Further, the probe control module 154 can instruct the temperature module 156 and / or the level module 158 to measure the electrical response from the thermocouples 120 and 122 and the resistive heating element 124, as further described below. Specifically, where the resistive heating element 124 is operated as a heater, the probe control module 154 can cause the temperature module 156 to monitor the electrical response from the thermocouples 120 and 122 to determine the fluid and ambient temperatures. Alternatively, where the resistive heating element 124 is operated as a sensor, the probe control module 154 can cause the temperature module 156 and / or the level module 158 to monitor the electrical response from the thermocouples 120 and 122 and / or the resistive heating element 124. That is, in one form, the probe control module 154 can control the probe 102 to detect the electrical response of one or more of the thermocouple 120, the thermocouple 122, and the resistive heating element 124. Thus, the probe 102 can operate as only a heater (without measuring temperature), as a heater-sensor (heating by the element 124 and measuring temperature by the thermocouples 120 and 122), or as only a sensor (without heating by the resistive heating element 124).

[0060] The temperature module 156 and the level module 158 measure the electrical response from the thermocouples 120 and 122 and the resistive heating element 124 and are configured to determine performance characteristics based on the electrical response and predetermined data. For example, one or more voltage-current measurement circuits measure the voltage / current at terminals 126, 128, and 130. The temperature module 156 calculates the fluid temperature and the ambient temperature based on the voltage measured at terminals 126 and 128, respectively, and predetermined information correlating the measured voltage to temperature. The level module 158 measures the electrical response of the resistive heating element 124 at terminal 130 to determine the total resistance of the element 124. The level module 158 determines the level using the resistance, the fluid temperature, the ambient temperature, and predetermined information (e.g., a lookup table and / or algorithm correlating temperature, resistance, and level).

[0061] The communication module 160 is configured to communicate with external devices, such as the heater control system 150 and / or a user interface (e.g., a display, a keyboard, a mouse). In one form, the communication module 160 transmits the performance characteristics to the heater control system 150 to control the heating system. The communication module 160 can also output the performance characteristics to a display visible to a user (not shown). In one form, the communication module 160 includes electronics, such as a transceiver, for establishing wireless or wired communication with the heater control system 150.

[0062] Referring to Figure 5 An example of a fluid monitoring routine 170 that measures one or more performance characteristics using the fluid sensor system 100 of the present disclosure is provided. The routine 170 can be performed periodically, or can be requested by an external device (e.g., the heater control system 150), or by a user communicably connected to the sensor system via, for example, a computing device.

[0063] At 172, the sensor system 100 measures the fluid temperature (T FL ) and the ambient temperature (T AMB ) using the fluid temperature sensor 120 and the ambient temperature sensor 122. At 174, the sensor system 100 determines whether the fluid temperature is the same as the ambient temperature. That is, the sensor system 100 determines whether there is a temperature gradient. If there is a difference, the sensor system 100 moves to 180. Otherwise, at 176, the sensor system 100 operates the resistive heating element 124 as a heater and determines whether there is fluid at 178. More specifically, at 176, the resistive heating element 124 operates as a heater along the length of the probe (i.e., the region of the probe that is immersed in the fluid and extends in the ambient atmosphere) to create a temperature differential that is verified by the sensor system 100 when it measures the fluid temperature and the ambient temperature.

[0064] After detecting the fluid, at 180, the sensor system 100 operates the resistive heating element 124 as a sensor, and then measures the fluid temperature, ambient temperature, and resistance of the resistive heating element at 182 as described above. Using the measurements and predetermined information, the sensor system 100 determines the level at 184 and outputs the performance characteristics (e.g., level, fluid temperature, and / or ambient temperature) to an external device.

[0065] The sensor system 100 can be configured in other suitable ways while remaining within the scope of the present disclosure, not limited to Figure 4 the processes described. For example, after determining the presence of a fluid, the system 100 can notify the heater control system 150 of the presence of the fluid and heat the fluid. In yet another variation, in the presence of a temperature gradient, the sensor system 100 can continuously monitor the level by applying a low stimulation power (e.g., 0.1 mA of current) to the resistive heating element. In yet another example, the sensor system 100 can continue to operate the resistive heating element 124 as a heater or turn off power to the element 124 after detecting the fluid.

[0066] The fluid sensor system can be configured in other suitable ways to measure one or more performance characteristics. For example, Figure 6A , Figure 6B , Figure 6C and Figure 6D different types of probes for measuring one or more performance characteristics are shown. Figure 6A A fluid sensor system 200 having a probe 202 and a control system 204 is shown. The probe 202 includes a fluid temperature sensor 206, a limit sensor 208 for measuring a high (maximum) limit (e.g., a maximum temperature at a particular location), and a resistive heating element 210. In one form, the fluid temperature sensor 206 is a thermocouple configured and operated in a similar manner as the fluid thermocouple 120 to measure the fluid temperature. The resistive heating element 210 is configured and operated in a similar manner as the resistive heating element 124. Instead of the ambient thermocouple 122, the probe 202 includes the limit sensor 208, which is provided as a thermocouple made of two different materials (e.g., Ml and M2) having different Seebeck coefficients.

[0067] The control system 204 is electrically connected to the fluid temperature sensor 206, the limit sensor 208, and the resistive heating element 210. The control system 204 is configured to operate the probe 202 and measure the fluid temperature and level in a similar manner as the control system 104. More specifically, in one form, the control system 204 obtains the ambient temperature from a cold junction compensation (CJC) disposed within the control system, for example, or a temperature sensor (not shown) disposed in the heater control system 150. With the ambient temperature, the control system 204 operates the probe 202 to measure the fluid temperature and / or the level.

[0068] Furthermore, the control system 204 is also configured to determine whether the fluid temperature is outside of a preset threshold based on the output of the limit sensor 208, and to perform a protective action based on a high fluid temperature. For example, in the case of the limit sensor 208 being a thermocouple, the temperature module of the control system 204 is configured to measure the voltage change across the terminals connected to the limit sensor 208, and to determine the temperature at the junction of the limit sensor 208 (i.e. the diagnostic temperature) based on predetermined data. The control system 204 can comprise a diagnostic module (not shown) that compares the diagnostic temperature to a preset temperature limit. If the diagnostic temperature is higher than the temperature limit, the diagnostic module performs a protective action, which can include notifying the heater control system 150 of a high fluid temperature and recommending to shut off the power to the heating element via the communication module 160. The protective action can also be to operate a power switch (e.g. a relay) connected between the power supply and the heater of the heater system (not shown) to shut off the power to the heater. Other suitable protective actions can also be implemented, such as notifying the operator, while remaining within the scope of the present disclosure.

[0069] The fluid temperature sensor of the probe 102, 202 can be other suitable sensors, and should not be limited to thermocouples. For example, Figure 6B A probe 230 is shown, which has a limit sensor 208 and a resistive heating element 210. Instead of a thermocouple, the probe 230 comprises a resistance temperature detector (RTD) 232 as the fluid temperature sensor. With the RTD 232, the temperature module of the control system 204 is configured to determine the fluid temperature based on the resistance feedback detected by the RTD 232 and predetermined information relating the resistance feedback to temperature.

[0070] With the probe 202 or the probe 230, the fluid sensor system is configured to measure multiple performance characteristics, such as fluid temperature, liquid level and / or diagnostic temperature, with one sensor device. Therefore, the complexity of the number of sensors providing information to the heater control system is reduced.

[0071] In yet another variant, Figure 6CA probe 250 is shown with a limit sensor 208 and a four-wire RTD, where one loop 252 is made of a high TCR material to form a resistive heating element, and a second loop 254 is made of the same material. Loop 208 forms a fluid temperature sensor. The high TCR loop can be Balco, nickel, copper, molybdenum, etc. Loops 252 and 254 are connected to an RTD 256 for providing more accurate resistance measurements to determine fluid level and fluid temperature. Both loops 252 and 254 are used simultaneously to detect fluid temperature by the RTD. The control system is configured to quickly switch between detecting fluid temperature and fluid presence or level by measuring the loop resistance of 252, 254, or both. One or both high TCR loops can be used as a heater or sensor, or both. In Figure 6D Another variation is shown where the probe 270 does not include a limit sensor, but rather has a similar four-wire RTD. Figure 6C

[0072] Figures 7A-7J Other wire configurations are shown that can be used in a probe to form one or more of a fluid temperature sensor, a resistive heating element, and an ambient temperature sensor. In Figures 7A-7J the dashed lines represent a first material (e.g., nichrome), the solid lines represent a high TCR material (e.g., nickel), and the nodes show thermocouple junctions.

[0073] In one form, the present disclosure is directed to a fluid sensor system including a probe and a control system. A portion of the probe is immersed in a fluid that is heated by a heating system. The probe includes a resistive heating element for determining fluid level and for creating a thermal gradient between the fluid and air.

[0074] As described herein, the probe of the fluid sensor system can be configured in various suitable ways to at least measure fluid temperature, fluid level, and provide a heating feature in the event the fluid temperature is the same as the air temperature. For example, the probe can be a four-wire mineral insulated RTD with nickel leads to measure fluid temperature and fluid level, with an integrated standard thermocouple to measure the environment. In this configuration, the RTD has a higher precision than the thermocouple for fluid temperature measurements. Alternatively, the probe can include a mineral insulated nickel-nichrome thermocouple, where the Seebeck effect provides the temperature of the fluid and the high TCR of the nickel provides the fluid level sensing, assuming the environment is cold junction compensation (CJC) in the control system. In this form, the number of wires disposed within the probe is reduced.

[0075] ​Based on the foregoing, the fluid sensor system of the present disclosure includes a finite length probe that includes at least one resistive heating element (e.g., a resistive circuit such as a resistive wire, foil, film) having a high temperature coefficient of resistance and at least one temperature sensor, such as an RTD or thermocouple, for determining fluid temperature. The probe can also include a second temperature sensor, such as an RTD or thermocouple, for measuring ambient temperature above the fluid.

[0076] As described herein, the probe can be configured in various suitable ways to include at least a resistive heating element and a fluid temperature sensor. For example: at least one wire for RTD and Zebereck effect temperature determination; at least one wire for fluid temperature and level detection purposes (resistive element); at least one wire for detecting fluid and ambient temperature; at least one wire for detecting ambient temperature and level detection; leads from a four wire RTD for measuring level.

[0077] The fluid sensor system also includes a control system configured to regulate power to provide a predetermined amount of power, such as a stimulation current applied to heat the resistive element, a low non-heating monitoring current applied to the resistive element, and / or a low monitoring current applied to an RTD if included for fluid temperature measurement.

[0078] The control system is configured to measure an electrical response, such as a voltage across the resistive element, a voltage from a thermocouple, and / or a voltage across an RTD. The control system is also configured to operate the resistive element of the probe as: (1) a heater by applying a heating stimulation current to the resistive heating element to create a temperature differential across a partially submerged probe, or (2) a sensor by applying a monitoring current (i.e., stimulation current) to the resistive heating element if a temperature differential already exists between the fluid and the surrounding environment. The stimulation current is applied to the resistive element to sense the presence of the fluid, and the response of the resistive element when a monitoring current is applied is used in combination with the fluid temperature to determine the level.

[0079] The control system can be configured to perform additional operations while remaining within the scope of the present disclosure. For example, the control system can store performance characteristics as historical measurements of the fluid, which can be used to form an operational model of the probe or heater system.

[0080] In another form, the present disclosure is directed to an integrated heater-sensor for generating heat and for measuring one or more performance characteristics of a heater system. Thus, in one form, the integrated heater-sensor includes at least one resistive heating element for generating heat and a temperature sensor for measuring a temperature at a specified location. For purposes of explanation, the heater system having the integrated heater-sensor is described as a liquid heater system for heating a liquid (e.g., oil), and the integrated heater-sensor is operable to measure at least one of a liquid level, a fluid temperature as a performance characteristic. However, the integrated heater-sensor of the present disclosure can be used in other applications (e.g., exhaust systems, flexible tube heaters, etc.), and should not be limited to liquid heater systems. Additionally, as further described below, the integrated heater-sensor can also be used to determine a preventive maintenance schedule for the system based on system characteristics and predetermined limits / algorithms, etc., or more generally, to determine various service parameters for the system.

[0081] Referring to Figure 8 The heater system 300 includes an integrated heater-sensor device 302 (i.e., integrated heater device 302) operable as a heater, a sensor, or a combination thereof, and a heater control system 304 configured to operate the integrated heater device 302 based on data from the device 302 and predetermined information including, but not limited to, algorithms, system models, predetermined set points, lookup tables, etc. The heater system 300 is operable to heat a liquid 306, such as oil, disposed in a vessel 308. More particularly, the heater control system 302 regulates power from a power source 310 to apply a desired amount of electrical power to the heater device 302. The amount of power applied to the heater device 302 is determined based on one or more performance characteristics measured by the heater device 302.

[0082] Here, the heater device 302 includes at least one multi-part resistive element defined by at least two different materials having different TCRs. More particularly, in one form, referring to Figure 9 The heater device 302 is configured to include a multi-part resistive element 320 embedded within a sheath 321. The multi-part resistive element 320 includes a first portion generally identified by reference numeral 322 and a second portion 324 generally identified by reference numeral 324. In one form, the first portion 322 is connected to a first power source pin 326, and the second portion 322 is connected to the first portion 322 and extends along the sheath 321.

[0083] The first portion 322 is defined by a first conductive material (e.g., nickel), and the second portion 324 is defined by a second conductive material (e.g., a nickel-chromium alloy) having a lower temperature coefficient of resistance (TCR) than the first conductive material. More specifically, both the first and second conductive materials generate heat, but the first conductive material, having a high TCR, exhibits a changing resistance due to temperature; therefore, as further described herein, the first conductive material is further used as a sensor. While specific examples of first and second conductive materials have been provided, other suitable materials may be used while remaining within the scope of this disclosure.

[0084] In one configuration, the first portion 322 is configured to extend along a designated area subjected to a temperature difference. For example, in Figure 9 In the middle, part of 322 is composed of the maximum liquid level and the minimum liquid level (L) Max and L Min )Limited liquid level range (L) R The first part 322 extends between the liquids 302, with the actual liquid level set between them. Therefore, the first part 322 is operable not only to heat the liquid 302, but also to detect the presence of fluid in a manner similar to the probe described above, and to measure the liquid level as described below.

[0085] In one configuration, the second portion 324 is fully immersed in the liquid 306 when the heater assembly 302 is placed in the container 308. Similar to the first portion 322, the second portion 324 is operable to heat the liquid, but its resistance does not change. Therefore, even during cold starts, the resistance of the heated portion 324 remains substantially constant. Hereinafter, the first and second portions may be referred to as the level sensor portion 322 and the heating portion 324, respectively.

[0086] By having a multi-part resistive element, the heater device 302 can exhibit the following properties: (1) the strength of the signal measuring the ratio of resistance change between high and low oil levels increases compared to a construction where the entire element is made of a high-TCR material; (2) the signal related to liquid level changes can be eliminated from resistance changes caused by liquid temperature changes when a small segment of high-TCR material is used, compared to a construction where the entire coil is made of a high-TCR material; and (3) the resistance of the entire high-TCR coil may be low at room temperature (e.g., when the heater device 302 is first started after an idle cycle), which can cause high currents when the design voltage is applied and until the resistive element heats up to near its operating temperature. Such high currents can overload the power supply circuit.

[0087] In one form, the multi-part resistive element 320 of the heater arrangement 302 includes a fluid temperature sensor and / or an ambient temperature sensor. More particularly, the multi-part resistive element 320 includes a third portion, generally identified by reference numeral 328, and defined by an electrically conductive material having a high TCR. For example, the third portion 328 can be made of the same material as the liquid level sensor portion 322. The third portion 328 is configured to be fully immersed in the liquid 306 to measure the fluid temperature when the element 320 is operated as a sensor. The fluid temperature is determined based on a change in resistance of the third portion 328, and since a majority of the multi-part resistive element 320 is formed of a low TCR material, the amount of error or ambiguity associated with temperature distribution along the entire length of the multi-part resistive element 320 is negligible or at least significantly reduced. Hereinafter, the third portion 328 can be referred to as a fluid temperature sensor portion 328.

[0088] In one form, the multi-part resistive element 320 is connected to a thermocouple junction 330 located above the maximum liquid level to measure the ambient temperature. For example, the junction 330 is defined by a first leg 332 and a second leg 334 made of a material having a different Seebeck coefficient than the first leg 332. Here, the second leg 334 also serves as another power leg connected to the heater control system 304. In one form, the first leg 332 is made of a material having a similar or identical Seebeck coefficient as the low TCR material of the heating portion 324.

[0089] The junction 330 as a thermocouple produces an electrical response (e.g., mV signal) as a function of temperature, and the heater control system 304 determines the temperature based on predetermined data such as a system model, a predetermined functional relationship, and / or a lookup table that correlates the electrical response to temperature. Such a thermocouple (TC) power leg is disclosed in U.S. Patent Application No. 14 / 725,537, filed May 29, 2015, entitled "RESISTIVE HEATER WITH TEMPERATURE SENSING POWER PINS," which is commonly owned with the present application, the contents of which are incorporated by reference herein. In addition to the ambient temperature, the temperature at the junction 330 is a function of the fluid temperature, the liquid level, and the heater power. The values in addition to the ambient temperature can be determined as described herein.

[0090] Based on the foregoing, the heater arrangement 302 is provided with a multi-part resistive element 320 having a liquid level sensor portion 322, a fluid temperature sensor portion 328, and a heating portion 324, and connected to a thermocouple junction 330 to measure the ambient temperature. The heater arrangement 302 can be configured in other suitable manners while remaining within the scope of the present disclosure. For example, with reference to Figure 10In one form, in addition to the multi-part resistive element 320, the heater arrangement 302B includes at least one uniform resistive element 340 that extends parallel to the multi-part resistive element 320 and is made of a low TCR material to generate heat. For clarity, both resistive elements 320 and 340 are resistive heating elements that generate heat. However, unlike the multi-part resistive element 320, the uniform resistive element 340 is made of one material with a low TCR material and is only operable as a heater; whereas the multi-part resistive element 320 is formed of multiple materials with different TCRs to operate as either a heater or a sensor. The uniform resistive element 340 is connected to the heater control system 304 via power supply pins 342 and 344, and thus, although the uniform resistive element extends parallel to the multi-part resistive element 320, it is a separate circuit from the multi-part resistive element 320. The resistive heating elements can be formed via wire, foil, thin film processes, or other suitable processes.

[0091] The sensor portions disposed along the multi-part resistive element 320 can be distributed among multiple multi-part resistive elements. For example, Figure 11 A heater arrangement 302C is shown that includes a first multi-part resistive element 350 with a liquid level sensor portion 320 and a second multi-part resistive element 352 with a fluid temperature sensor portion 328. Although not shown, the heater 320C can also include one or more uniform resistive elements. In another variation, the integrated heater-sensor of the present disclosure can not include all of the sensor portions described herein. For example, Figure 11 The heater arrangement 302C of FIG. 3C can include only the multi-part resistive element 350 and not 352.

[0092] Other suitable configurations of the integrated heater can also be used while remaining within the scope of the present disclosure. For example, in one form, a thermocouple junction can be disposed at the power supply pins of the uniform resistive element instead of the multi-part resistive element. In another example, instead of a thermocouple junction, the multi-part resistive element can include a portion made of a first conductive material (i.e., a material with a high TCR) that is positioned above the maximum liquid level to measure the temperature of the ambient air and form an ambient sensor portion. In one form, the resistance of the first conductive material is selected to be low enough to avoid overheating that portion of the heater at the maximum duty cycle, maximum locally generated power due to the current generated by the heater operation, and the maximum ambient temperature conditions.

[0093] Based on the configuration of the heater arrangement 302, the heater control system 304 is configured to operate the heater arrangement 302 as, for example, a heater, a heater-sensor, or a sensor. Referring to Figure 12In one form, the heater control system 304 includes a heater control module 380, a performance characteristic module 382, and a power module 384. The heater control module 380 is configured to control the operation of the heater device 302 (e.g., as a heater, a sensor, a heater-sensor, or an off state). For example, if the heater device 302 includes at least one multi-part resistive element 320 and at least one uniform resistive element or at least two multi-part resistive elements 320, the heater device 302 can operate as a heater, a heater-sensor, and a sensor. Alternatively, if the heater device 302 includes one multi-part resistive element, the heater device 302 can operate as a heater or a sensor.

[0094] As a heater, the heater control module 380 has a first power level (e.g., 75 watts, 100+ watts, or other suitable power based on system characteristics) applied to the multi-part resistive element 320 and / or the uniform resistive element. As a sensor, the heater control module 380 operates the heater device to detect an electrical characteristic of at least one of the multi-part resistive elements 320 by applying a small amount of power (i.e., stimulation power) to the multi-part resistive element 320 (e.g., 0.1 mA current). In one form, as a sensor, the heater control module 302 applies stimulation power to at least one of the multi-part resistive elements and does not apply power to the uniform resistive element and / or other multi-part resistive elements. As a heater-sensor, the heater control module 380 is configured to apply low stimulation power to at least one of the multi-part resistive elements and the first power level to the uniform resistive element and / or other multi-part resistive elements.

[0095] In one form, the heater control module 380 can switch between various operational states (e.g., heater, sensor, heater-sensor, off state) based on a predetermined cycling program (e.g., operate as a sensor / heater-sensor for 5 minutes, then as a heater). Other suitable control schemes can be used to switch the heater control module 380 between different states.

[0096] Similar to the power module 152 of the sensor system, the power module 152 is configured to supply power to the electronics within the heater control system 304 and apply specified power limits to the heater device 302 based on the selected operation of the heater device 302 determined by the heater control module 380. For example, the power module 152 can include a power regulator circuit (e.g., voltage divider, voltage converter, etc.) for regulating power from the power source 164 and applying the regulated power to the probe 102 and the heater device 302.

[0097] Using the electrical response of the heater, the performance characteristic module 382 calculates one or more performance characteristics of the heater device 302 and provides the calculated values to the heater control module 380 to control the heater device 302. For example, the fluid level is a function of the magnitude of the change in electrical resistance and the rate of change of electrical resistance over time at a known or predetermined power level. Thus, the performance characteristic module 382 uses a system model, a functional relationship (e.g., a predetermined algorithm), or a lookup table that maps fluid levels to changes in electrical resistance based on the change in electrical resistance and the rate of change values to determine the fluid level. The electrical response is a function of the physical characteristics (geometry, materials, etc.) defined by the system.

[0098] The heater control system 304 can be configured to perform other operations while remaining within the scope of the present disclosure. For example, in one form, the heater control system 304 can communicate with external devices, such as computing devices, displays, keyboards, buttons, touchscreens, etc., for receiving data from a user and / or for displaying information about the heater system. For example, the heater control system 304 can receive temperature setpoints, commands for controlling the operational state of the heater, and / or other information via the external devices. In turn, the heater control system can display, for example, a graphical user interface that shows selectable commands, the current operational state of the heater, the current fluid temperature, the fluid level, the mass, and / or other suitable information.

[0099] In one form, an integrated heater with sensing capabilities can be implemented as part of a virtual sensing system to determine parameters of a heating system without using additional sensors. For example, a virtual sensing system with an integrated heater-sensor of the present disclosure can be used to determine parameters such as: (1) fluid reservoir temperature, (2) fluid reservoir level, and (3) fluid reservoir mass, where at least one heater maintains the temperature, level, and mass of the fluid in the system. One such virtual sensing system is provided in co-pending application U.S. Application No. 15 / 447,942, filed March 2, 2017, entitled “VIRTUAL SENSING SYSTEM,” which is commonly owned with the present application and is incorporated by reference herein in its entirety. This application describes a virtual sensing system for a heating system disposed in an exhaust system. Generally, a control system is configured to calculate one or more values of the heating system based on a set of known variables and a predetermined algorithm. Using the calculated values and physical characteristics of the heating system, the control system controls the heater. Such a control system can be implemented for a fluid heating system in which a liquid, such as oil, is heated.

[0100] For example, for the heating system of the present disclosure, the virtual sensing system can be used to determine the fluid temperature, fluid level, and / or fluid mass if at least two of the three other parameters are known. For example: the fluid reservoir temperature can be determined if the fluid reservoir level and mass are known; the fluid reservoir level can be determined if the fluid reservoir temperature and mass are known; and the fluid mass can be determined if the fluid reservoir temperature and level are known.

[0101] In implementing the virtual sensing system, in one form, the heater control system of the present disclosure is configured to receive at least one input from among: a fluid level, a fluid mass, a parameter derived from a physical characteristic of the heating system, and combinations thereof. The at least one input also includes at least one of a power input to a heater of the heater system and a system input. The physical characteristics can include, for example, a resistance wire diameter, a MgO (insulation) thickness, a sheath thickness, an electrical conductivity, a specific heat and a density of the construction material, a heat transfer coefficient, an emissivity of the heater and fluid conduit, and other geometry and application related information.

[0102] In one form, where the heater has a sheath, the control system is configured to determine a sheath temperature (T s ) of the heater based on a parameter derived from a physical characteristic of the heating system. Alternatively, the heater can be a layered heater having a heater surface temperature and the heater control system is configured to determine the heater surface temperature (T s ) by, for example, the following equation, where:

[0103]

[0104] c s is a specific heat of the heater sheath material

[0105] m s is a weight of the sheath material

[0106] T s is a temperature of the sheath material

[0107] T v is a temperature of the fluid (oil cylinder)

[0108] T1 is a temperature of the MgO insulation material

[0109] D1 is a thickness of the MgO insulation material

[0110] D S is a thickness of the sheath material

[0111] K1 is a thermal resistivity of the MgO material

[0112] A1 is a cross-sectional area of the MgO material

[0113] k S Thermal resistivity of the sheath material

[0114] A s The cross-sectional area of ​​the sheath

[0115] h C1 The convection coefficient of the sheath

[0116] A V1 The cross-sectional area of ​​the fluid (cylinder) exposed to the sheath

[0117] The heater control system can also be configured to calculate the fluid temperature (T) based on the physical characteristics of the heating system. v T can be determined by, for example, the following equation: v :

[0118]

[0119] c v Specific heat of fluid storage tank

[0120] m v It is the weight of the fluid storage device.

[0121] T s Temperature of the sheath material

[0122] T v Temperature of the fluid (cylinder)

[0123] T ab ambient temperature

[0124] D S For the thickness of the sheath material

[0125] K1 is the thermal resistivity of MgO material.

[0126] A1 is the cross-sectional area of ​​the MgO material.

[0127] k S Thermal resistivity of the sheath material

[0128] A s The cross-sectional area of ​​the sheath

[0129] h C1 The convection coefficient of the sheath

[0130] A V1 The cross-sectional area of ​​the fluid (cylinder) exposed to the sheath

[0131] h env The convection coefficient of the fluid storage tank to the environment.

[0132] A envCross-sectional area of the fluid reservoir exposed to the environment

[0133] Thus, parameters derived from the physical characteristics of the heating system can determine at least one of the sheath temperature (T s ) and the fluid temperature (T v ). The fluid temperature (T v ) can be obtained from the integrated heater of the present disclosure and / or the fluid sensor system of the present disclosure, as described herein. With the virtual sensing system, the heater control system of the present disclosure is operable to predict temperatures associated with the heater and temperatures associated with the fluid without specific sensors. It should be noted that other equations can be used as part of the virtual sensing system and should not be limited to the equations provided.

[0134] The heater control system can determine the heater sheath temperature based on at least one of the heater geometry, the input power, the high TCR element resistance, the thermocouple power supply pins with system properties, the oil temperature, and a system model. Alternatively, the TCR and power mapping together can be used to calculate the sheath temperature. These methods provide benefits such as faster heating of the liquid without burning in transient, enhanced safety, increased temperature sensing accuracy compared to cases where sensors are connected, increased liquid life, and reduced over-heating of the liquid, among others.

[0135] In one form of the present disclosure, the heater control system is configured to perform a self-calibration to calibrate the heating system. The self-calibration includes measuring the fluid temperature after cooling to obtain a steady state at room temperature using, for example, at least one of a cold junction compensation sensor of a TC power supply pin system, a small surface mount RTD, or a thermistor on a printed circuit board (PCB). After measuring the steady state room temperature, the control system applies a precise measured power pulse to the heater. The measured power pulse should be short enough so that the temperature response is independent of the amount of fluid in the fluid reservoir. Next, the observed time-temperature response is compared to a predetermined time-temperature response measured when the fluid heating system was formed, such as during factory calibration or during installation of the fluid heating system. By comparing the time-temperature responses, a second calibration point is obtained, for example, at a peak temperature or after a predetermined time period and at an elevated temperature (in addition to the room temperature point). In one form, a resistance slope response can also be used instead of or in addition to the second calibration point.

[0136] For the self-calibration process, instead of waiting for a steady state at room temperature, a temperature rate of change signal (i.e., rate of change of resistance or millivolts) from the heater is measured and a system model is used to infer what steady state the signal will settle to. The rate of change is then calibrated to a room temperature measurement at, for example, the PCB.

[0137] In another form, self-calibration includes waiting until the reservoir is empty, heating the wire above the Curie point, and measuring the resistance at the point of maximum TCR slope (derivative of the TCR curve). In one example, if nickel is used as the high TCR material, the maximum TCR slope point is 358.2°C. Calibration also includes using the resistance from the power burst as a potential second calibration point.

[0138] In another self-calibration, the calibration point is provided as a local maximum of the nickel-chromium resistance at the calibration point (e.g., 550°C for nickel-chromium alloy 80). Calibration includes waiting until the reservoir is empty, for example, after filtering or cleaning, heating the wire to 550°C. Next, the heater is stimulated with a high current so that the wire reaches 550°C and the sheath remains cooler. The sheath should be below the flash point of the liquid to inhibit high stresses on the wire and increase the life of the heater.

[0139] A separate liquid temperature sensor can also be used for self-calibration. Specifically, calibration includes waiting for the heater temperature to reach an equilibrium temperature with the liquid, calibrating at several temperatures using a separate liquid temperature sensor, and using a priori information to infer an upper limit on the liquid temperature.

[0140] Other features / steps can be used for self-calibration while remaining within the scope of the present disclosure. For example, the following can be used for self-calibration: nickel-iron alloys with unique tunable properties like inflection points or peak slope; and power versus resistance response history inputs such as start-up or during controlled cooling. Predetermined and predictable drift characteristics of at least one heater circuit can be used to eliminate the need for in-field calibration. Self-calibration adjustments can occur periodically during the life of the heating system.

[0141] In one form, the control system can also be configured to include a system model for preventing physical damage to the heater system or other unforeseen effects. For example, the system model is configured to predict the rate of change of temperature over time associated with various operating states or the rate of change of temperature for a test energy pulse (e.g., cool the heater to a few degrees below the target setpoint before applying a measured energy pulse and observe the response). Resistance or mV changes outside of expected ranges can mean that there is a problem and can generate or use an alarm or error code in some other way to facilitate a decision about whether to allow continued operation.

[0142] With respect to self-calibration and virtual sensing features, the fluid temperature can be matched to the CJC by using a system model, which can be an exponential decay equation with parameters to be determined from the change in cooling rate over time and will be used to infer the final steady state temperature. If the room temperature is not constant, a more complex model can be required. For example, a CJC or small, inexpensive, PCB mounted sensor can be used to measure the room temperature and the system model can then determine the temperature difference between the fluid and the room based on the cooling rate, providing a temperature for calibrating the fluid or heater temperature sensing feature.

[0143] The fluid sensor system and heater system with integrated heater-sensor of the present disclosure can reduce the number of independent sensors for the heater system. The virtual sensing features described herein can be implemented as part of the fluid sensor system and / or the heater system with integrated heater-sensor.

[0144] It should be noted that the present disclosure is not limited to the embodiments described and shown by way of examples. Various modifications have been described and further modifications are part of the knowledge of a person skilled in the art. Any substitution of these and further modifications and technical equivalents can be added to the description and drawings without departing from the scope of the present disclosure and the protection of the patent.

Claims

1. An integrated heater apparatus for heating a fluid, the integrated heater apparatus comprising: a multi-part resistive element configured to measure one or more performance characteristics of the fluid, the multi-part resistive element having a first part defined by a first electrically conductive material and a second part defined by a second electrically conductive material having a lower temperature coefficient of resistance than the first electrically conductive material, wherein the multi-part resistive element is operable as a heater to generate heat and as a sensor, the first part of the multi-part resistive element is configured to extend along a designated area to measure a first performance characteristic of the fluid, the second part is coupled to the first part to extend beyond the designated area and the designated area is a liquid level range, the multi-part resistive element includes a third part defined by an electrically conductive material having a higher temperature coefficient of resistance than the temperature coefficient of resistance of the second electrically conductive material, the third part is connected to the second part of the multi-part resistive element, and the third part is configured to measure a fluid temperature.

2. The integrated heater apparatus of claim 1, further comprising: a first leg connected to the multi-part resistive element; and a second leg connected to the first leg and having a different Seebeck coefficient than the first leg, wherein the first leg and the second leg form a thermocouple junction to measure a temperature at a first location as a second performance characteristic. the first leg is connected to the third part of the multi-part resistive element, and the first leg has a substantially same temperature coefficient of resistance as the temperature coefficient of resistance of the second part of the multi-part resistive element.

3. The integrated heater device of claim 2, wherein, the first location is outside the designated area.

4. The integrated heater device of claim 2, wherein, 5. The integrated heater apparatus of claim 1, further comprising: a uniform resistive element defined by a material having a lower temperature coefficient of resistance than the temperature coefficient of resistance of the first electrically conductive material of the multi-part resistive element, wherein the uniform resistive element is operable as a heater.

6. The integrated heater apparatus of claim 1, further comprising: at least two of the multi-part resistive elements, wherein as the sensor, one multi-part resistive element is configured to measure a different performance characteristic of the fluid than another multi-part resistive element.

7. The integrated heater apparatus of claim 1, further comprising a sheath, wherein the multi-part resistive element is embedded in the sheath.

8. A heater system for heating a fluid in a container, the system comprising: an integrated heater apparatus operable as a heater to heat a fluid and / or as a sensor to measure one or more performance characteristics, the integrated heater apparatus comprising: ​ A multi-part resistance element, wherein the multi-part resistance element is defined by at least two parts formed of at least two materials, wherein a first part is formed of a material having a higher temperature coefficient of resistance than a second part, and the first part extends from and is connected to the second part, the first part configured to extend along a designated area to measure a first performance characteristic of the fluid, the second part coupled to the first part to extend beyond the designated area and the designated area is a level range; and a control system configured to operate the integrated heater device as the sensor to measure a resistance of the multi-part resistance element, wherein the control system determines the one or more performance characteristics based on the resistance of the multi-part resistance element, the multi-part resistance element includes a third part defined by a conductive material having a higher temperature coefficient of resistance than a temperature coefficient of resistance of a second conductive material, the third part connected to the second part of the multi-part resistance element, and the third part configured to measure a fluid temperature.

9. The heater system of claim 8, wherein, the heater device includes at least two of the multi-part resistance elements, wherein one multi-part resistance element is configured to measure a different performance characteristic than another multi-part resistance element.

10. The heater system of claim 9, wherein, the control system is configured to calculate a first performance and a second performance characteristic based on the resistance of each of the multi-part resistance elements, and a third performance characteristic based on the first performance and the second performance characteristics and a determination system model.

11. The heater system of claim 10, wherein, the first performance and the second performance characteristics include a fluid temperature and a level, and the third performance characteristic is a fluid mass.

12. The heater system of claim 8, wherein, in the designated area, the first part is partially immersed in the fluid to detect a level as one of the performance characteristics.

13. The heater system of claim 8, further comprising: a uniform resistance element defined by a material having a lower temperature coefficient of resistance than a temperature coefficient of resistance of the first part of the multi-part resistance element.

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