Detection of Abnormal Operating Conditions of Heat Exchanger

Abstract

A method for detecting an abnormal operating condition in a heat exchanger is provided. The method includes determining an actual current through the heat exchanger, using the actual current to indicate the abnormal operating condition, and declaring a fault condition. Comparing the baseline current to the actual current includes normalizing the actual current, calculating a difference between the normalized actual current and the baseline current, and determining that the difference is less than zero.

Description

Technical Field

[0001] Cross - Reference to Related Applications This application claims the benefit of U.S. Provisional Patent Application No. 63 / 222,619, entitled "DETECTION OF ABNORMAL HEAT EXCHANGER OPERATING CONDITION", filed on July 16, 2021, the disclosure of which is hereby incorporated by reference in its entirety for all purposes.

[0002] The subject matter described herein generally relates to methods for detecting abnormal operating conditions of a heat exchanger, and more particularly to methods for detecting a fault condition of a cleaning heater.

Background Art

[0003] In the context of in vitro diagnostic medical devices (IVDs), a probe is cleaned by a cleaning fluid warmed to a desired temperature by a cleaning heater. The heater is primed by a vacuum pump that draws fluid from a reservoir into the heater. When fully and properly primed, there are few or no air bubbles in the fluid, and a thermistor located at the outlet of the heater can accurately sense the temperature of the fluid.

[0004] For many reasons, the heater may not be properly primed. The heater may be improperly primed or not primed at all. Even if the heater was properly primed, leakage or other factors may compromise that priming.

[0005] Regardless of the cause, there are bubbles or air pockets in the fluid of the heater with improper priming. The presence of these bubbles and air pockets results in two situations. As the first situation, the heat transfer between the heating element of the heat exchanger and the fluid is reduced. As the second situation, the thermistor cannot accurately sense the temperature of the fluid and reads a temperature lower than the actual temperature. In response, the system continues to operate to raise the temperature of the fluid. As a result, the heater begins to overheat and ultimately causes damage to the heater.

[0006] Before the heater begins to overheat, it would be desirable to be able to detect that the priming of the heater is improper. This can be achieved by adding a pressure sensor to the heater to detect abnormal flow, but it would be preferable to be able to perform the detection using only existing equipment. Ideally, the detection would be easily implemented with the existing software and hardware configuration of the heater.

Summary of the Invention

Problems to be Solved by the Invention

[0007] An ideal detection system should be sensitive and accurate. An ideal detection system should also be immediate, so that the heater can be shut off before it is damaged. An ideal detection system should also enable on-site monitoring. Furthermore, an ideal detection system will not only indicate that a fault condition has occurred, but also the type of fault condition.

Means for Solving the Problems

[0008] In some embodiments, a method for detecting abnormal operating conditions of a heat exchanger is provided. In some embodiments, the method includes determining an actual current through the heat exchanger, using the actual current to indicate abnormal operating conditions, and declaring a fault condition.

[0009] In other embodiments, the method further includes determining a baseline current. In some embodiments, the step of using the actual current to indicate an abnormal operating condition includes comparing the baseline current with the actual current.

[0010] In other embodiments, the step of determining the baseline current includes operating the heat exchanger under baseline conditions and measuring the current passing through the heat exchanger. In some embodiments, the current passing through the heat exchanger operating under baseline conditions is the baseline current.

[0011] In other embodiments, the baseline condition is that a fully primed heat exchanger starts from a cold start under worst conditions and maximum duty load.

[0012] In other embodiments, the step of comparing the baseline current with the actual current includes normalizing the actual current, calculating the difference between the normalized actual current and the baseline current, and determining that the difference is less than zero. In some embodiments, this step further includes determining a baseline signal-to-noise ratio, calculating an actual signal-to-noise ratio, comparing the actual signal-to-noise ratio with the baseline signal-to-noise ratio, and determining that the actual signal-to-noise ratio is greater than the baseline signal-to-noise ratio.

[0013] In other embodiments, the baseline condition represents a specific type of abnormal operating condition. In some embodiments, a specific type of abnormal operating condition is declared.

[0014] In other embodiments, one or more types of abnormal operating conditions are selected from the group consisting of unprimed, partially primed, and primed.

[0015] In some embodiments, the process of using the actual current to indicate abnormal operating conditions includes determining a baseline temperature and determining a reference temperature resistance and a thermoelectric resistance coefficient of the heat exchanger. In some embodiments, this process further includes calculating an actual temperature using the reference temperature resistance and the thermoelectric resistance coefficient of the heat exchanger and determining that the actual temperature of the heat exchanger is greater than the baseline temperature.

[0016] In other embodiments, the baseline temperature represents a specific type of abnormal operating condition. In some embodiments, a specific type of abnormal operating condition is declared.

[0017] In other embodiments, the abnormal operating conditions are selected from the group consisting of unprimed, partially primed, and primed.

[0018] In other embodiments, the process of declaring a fault condition includes displaying a visual indication that a fault condition exists via a graphical interface.

[0019] In other embodiments, the method further includes automatically shutting off the heat exchanger.

[0020] In other embodiments, the method further includes shutting off equipment that relies on the heat exchanger to function properly.

[0021] In some embodiments, a system for detecting abnormal operating conditions of a heat exchanger is provided. In some embodiments, the system includes a heat exchanger, a drive circuit having a current measurement device, a processor, and a graphical display. In some embodiments, the drive circuit is configured to drive the heat exchanger. In some embodiments, the current measurement device is configured to measure the current passing through the drive circuit and thus through the heat exchanger. In some embodiments, the processor is configured to operate the heat exchanger, determine the actual current passing through the heat exchanger, use the actual current to indicate abnormal operating conditions, and declare a fault condition. In some embodiments, the graphical display is configured to display an indication that a fault condition has been declared.

[0022] In other embodiments, the current measurement device is a sense resistor.

[0023] In other embodiments, the processor is further configured to determine a baseline current. In some embodiments, the processor is further configured to compare the baseline current with the actual current for the step of using the actual current to indicate abnormal operating conditions.

[0024] In other embodiments, the processor is further configured to normalize the current, calculate the difference between the actual current and the baseline current, and determine that the difference is less than zero for the step of using the actual current to indicate abnormal operating conditions.

[0025] In other embodiments, the processor is further configured to determine a baseline temperature and determine a reference temperature resistance and a thermoelectric resistance coefficient of the heat exchanger for the step of using the actual current to indicate abnormal operating conditions. In some embodiments, the processor is further configured to calculate the actual temperature of the heat exchanger using the actual current, the reference temperature resistance, and the thermoelectric resistance coefficient, and determine that the actual temperature is greater than the baseline temperature.

[0026] In other embodiments, the processor operates the heat exchanger under a plurality of duty conditions to determine the reference temperature resistance and the thermoelectric resistance coefficient of the heat exchanger; measures the current and temperature for each of the duty conditions; and is further configured to calculate the reference temperature resistance and the thermoelectric resistance coefficient of the heat exchanger using the measured current and temperature.

[0027] In some embodiments, a computer program configured to detect a fault condition of a heat exchanger is provided. In some embodiments, the computer program includes a computer-readable storage medium in which program instructions are embodied together. In some embodiments, the program instructions executable by a processor cause the actual current through the heat exchanger to be determined, use the actual current to indicate abnormal operating conditions, declare a fault condition, and display an indication that the fault condition has been declared.

[0028] Additional configurations and advantages of the present invention will become apparent from the following detailed description of exemplary embodiments, which proceeds with reference to the accompanying drawings.

[0029] The above and other aspects of the present invention will be best understood from the following detailed description when read in conjunction with the accompanying drawings. For the purpose of illustrating the present invention, these drawings show currently preferred embodiments, but it is to be understood that the invention is not limited to the specific means disclosed. The drawings include the following figures.

Brief Description of the Drawings

[0030]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

[0031] The present disclosure describes a method for detecting an abnormal operating condition of a heat exchanger, a system for detecting an abnormal operating condition of a heat exchanger, and a computer program product for detecting an abnormal operating condition of a heat exchanger.

[0032] FIG. 1 is a diagram of one embodiment of a cleaning heater circuit 100. A cleaning liquid is drawn from a cleaning liquid reservoir 110 into a cleaning heater 130 by a vacuum pump 170. After reaching a desired temperature, the cleaning liquid is sent to a cleaning probe discharge system 180. The cleaning liquid exits the cleaning probe discharge system 180 through a cleaning probe 181 and enters a cuvette 190. In this way, the cuvette 190 is cleaned with the warmed cleaning liquid.

[0033] As shown in FIG. 1, a thermistor 131 is provided at the outlet of the cleaning heater 130. As discussed above, this thermistor 131 reads an unnaturally low temperature (i.e., the measured temperature is lower than the actual temperature) in a cleaning heater 130 with improper priming.

[0034] The heat exchanger can be powered by a pulse width modulation ("PWM") drive. In many cases, these PWM drives have sense resistors. For example, FIG. 2 is an example of a drive circuit 200 that drives a heat exchanger 230. In this example, an H-bridge circuit is used. This circuit houses four transistors 215a, 215b, 215c, and 215d. Each transistor has an associated base terminal (216a, 216b, 216c, 216d), and a PWM control signal based on PWM control logic for a switching sequence is applied to these base terminals, and its switching speed is determined by the duty cycle calculated by the controller. A positive potential is applied to transistors 215a and 215b from 217a and 217b. This circuit can operate with transistors 215a and 215c on and transistors 215b and 215d off. This circuit can also operate with transistors 230b and 230c off and transistors 230a and 230d on. The current through this circuit is measured by sense resistor 221. The circuit ground is 201.

[0035] FIG. 3 is another example of a drive circuit 300 that can drive a heat exchanger 330. In this embodiment, the drive circuit is a half H-bridge circuit for a PWM drive 320 to drive the heat exchanger. This circuit houses two transistors 315e and 315f. This circuit also includes a thermistor 331 located at the output of the heat exchanger 330, a signal conditioning element 341, an analog-to-digital converter 342, a digital low-pass filter 343, a heater reference temperature element 344, a controller 310, and a PWM drive 320. In some embodiments, the controller 310 is a proportional-integral-derivative ("PID") controller. The current through this circuit is measured by sense resistor 321.

[0036] The above two examples provide examples of drive circuits that can drive a heat exchanger, but the subject matter of this specification is not limited by these two examples.

[0037] By comparing the actual current with the baseline current, fault conditions can be detected. The resistance of the heat exchanger increases as its temperature rises. Assuming a constant power supply and according to Ohm's law, when the temperature rises and the resistance of the heat exchanger increases, the current passing through the heat exchanger decreases. If the baseline current is known, a smaller actual current than the baseline current can indicate a fault condition of the heat exchanger.

[0038] In addition, by comparing the actual temperature with the baseline temperature, fault conditions can be detected. Inappropriate priming causes the temperature of the heat exchanger to rise, so the actual temperature of the heat exchanger can indicate a fault condition. As discussed above, the thermistor located at the outlet of the heat exchanger cannot provide an accurate temperature reading of an improperly primed heat exchanger. However, if the power and current passing through the circuit are known, the actual temperature can be calculated.

[0039] The resistance of the heat exchanger is defined as follows: R(T)=R Ref ·(1 + α·[T Htr -T Ref )

[0040] Here, R(T) is the resistance of the heat exchanger at a specific temperature, R Ref is the resistance at the reference point, α is the thermoelectric resistance coefficient of the heat exchanger, T Htr is the actual temperature of the heat exchanger, and T Ref is the temperature of the heat exchanger at the reference point. Substituting this formula into Ohm's law and solving it can obtain the actual temperature of the heat exchanger: V = I·R V = I·R Ref ·(1 + α·[T Htr -T Ref )

Equation

[0041] Here, γ is the duty cycle, V Ps is the maximum power input to the heat exchanger, I Htr is the actual current, and α is the thermoelectric resistance coefficient of the heat exchanger. If all of these values are known, the actual temperature of the heat exchanger can be calculated and compared with the baseline temperature.

[0042] The subject matter of this specification discloses practical applications of these phenomena.

[0043] Method for Detecting Abnormal Operating Conditions of a Heat Exchanger Some embodiments of the present disclosure are directed to a method for detecting a fault condition of a heat exchanger using the actual current passing through the heat exchanger.

[0044] FIG. 4 is a diagram of an embodiment of a method for detecting abnormal operating conditions of a heat exchanger. In some embodiments, the method includes, in step 410, determining the actual current passing through the heat exchanger, in step 420, using the actual current to indicate an abnormal operating condition, and in step 430, declaring a fault condition.

[0045] Method for Detecting Abnormal Operating Conditions of a Heat Exchanger: Current Threshold Some embodiments of the present disclosure are directed to a method for detecting a fault condition of a heat exchanger by comparing the actual current with a baseline current.

[0046] FIG. 5 is a diagram of an embodiment of a method 500 for detecting abnormal operating conditions of a heat exchanger by comparing the actual current with a baseline current. In some embodiments, the method has a calibration step and a detection step. In some embodiments, the calibration includes, in step 510, operating the heat exchanger under baseline conditions, and in step 520, measuring the current passing through the heat exchanger under those conditions to obtain a baseline current. In a preferred embodiment, the baseline conditions are that a properly primed heat exchanger starts from a cold start under worst conditions and maximum duty load. In some embodiments, this current represents the baseline current.

[0047] In some embodiments, the maximum duty cycle is the maximum temperature rise ("ramp-up") that is required to account for variations in heater element resistance, power supply voltage, ambient temperature, and other uncertainties. In some embodiments, these variations are considered to span multiple heat exchangers, and variations between heat exchangers are also considered. The allowable maximum duty cycle is typically set in advance. In some applications, if the heat exchanger remains at the maximum duty cycle for a period longer than the set period, the heat exchanger is shut off. In some embodiments, the maximum duty cycle is the same as the worst-case condition.

[0048] In some embodiments, a calibration process can be performed on multiple heat exchangers to calculate a baseline current based on the average current of the heat exchanger under baseline conditions.

[0049] In some embodiments, the detection process includes steps 530, 540, and 550. In some embodiments, in step 530, the actual current through the heat exchanger is measured under actual operating conditions. In other embodiments, the actual current is the average of the actual currents measured over a period of time or at several points in time.

[0050] In some embodiments, in step 540, the actual current through the heat exchanger is compared to the baseline current. In some embodiments, comparing the actual current to the baseline current includes calculating the change between the baseline current and the actual current. In some embodiments, the formula is as follows:

Equation

[0051] Here, ΔI is the change in current, γ max is the maximum duty cycle, γ is the actual duty cycle, and I Htr (t i) is the actual current of the heat exchanger,

Number

Number

[0052] where SNR is the actual signal-to-noise ratio and ΔI is the change in current,

Number

[0053] In the above-described embodiments, the normalized actual current is compared with the baseline current to declare a fault condition. However, this method can also be used to indicate the type of fault condition, such as unprimed, partially primed, or primed. In those embodiments, the baseline current is associated with each fault condition and is, for example, an unprimed baseline current, a partially primed baseline current, and a primed baseline current. The normalized actual current can be compared with each of these baseline currents to declare a specific fault condition. This enables on-site monitoring of the heat exchanger.

[0054] After a fault condition is declared, some embodiments further include providing a visual or audible indication of the fault condition. For example, in some embodiments, an alarm can be sounded. In some embodiments, a light can blink or turn yellow. In other embodiments, words such as "fault condition" are displayed on a graphical user interface. In embodiments that indicate the type of fault condition, words such as "unprimed", "partially primed", "primed" can be displayed on the graphical interface. In other embodiments, other indicators can also be used to indicate the type of fault condition. In some embodiments, when indicating a fault condition, the method further includes automatically shutting off the heat exchanger. In still other embodiments, the method further includes sending a signal to downstream equipment. In some embodiments, the method further includes shutting off downstream equipment.

[0055] Method for detecting abnormal operating conditions of a heat exchanger: Temperature threshold Some embodiments of the present disclosure are directed to a method for detecting abnormal operating conditions of a heat exchanger by comparing a calculated actual temperature to a baseline temperature.

[0056] FIG. 6 is a diagram of one embodiment of a method 600 for detecting abnormal operating conditions of a heat exchanger by comparing a calculated actual temperature to a baseline temperature. In some embodiments, the method has a calibration step and a detection step. In some embodiments, the calibration step includes steps 610 and 620. In some embodiments, the calibration step includes, in step 610, determining a baseline temperature. In some embodiments, the calibration step includes, in step 620, determining a reference temperature resistance and a thermoelectric resistance coefficient of the heat exchanger. The reference temperature resistance of the heat exchanger is the resistance of the heat exchanger at a reference temperature. In some embodiments, step 620 includes operating the heat exchanger under different duty cycle conditions, measuring the current and temperature of the heat exchanger under those different duty conditions, and using those values to estimate the reference temperature resistance and the thermoelectric resistance coefficient of the heat exchanger. In other embodiments, the reference temperature resistance and the thermoelectric resistance coefficient of the heat exchanger are known.

[0057] In some embodiments, steps 610 and 620 can be performed on a plurality of heat exchangers to estimate the average reference temperature resistance and the thermoelectric resistance coefficient of the heat exchanger.

[0058] In some embodiments, the detection step includes, in step 630, measuring the actual current passing through the heat exchanger under actual operating conditions. In other embodiments, the actual current is the average of the actual currents measured over a period of time or at several points in time. In some embodiments, in step 640, the actual temperature is calculated using the actual current according to the following mathematical formula:

Equation

[0059] where T Htr is the actual temperature, γ is the actual duty cycle, V Ps is the maximum power input to the heater, I Htr is the actual current, and R Refis the reference temperature resistance of the heat exchanger, α is the thermoelectric resistance coefficient of the heat exchanger, and T Ref is the temperature of the heat exchanger at the reference point. In some embodiments, the reference temperature resistance and the thermoelectric resistance coefficient of the heat exchanger estimated during the calibration process are R Ref and α are used. In other embodiments, the reference temperature resistance and the thermoelectric resistance coefficient are known in advance and thus do not need to be inferred by the calibration process.

[0060] In some embodiments, in step 650, the actual temperature is compared with the baseline temperature. In some embodiments, in step 660, if the actual temperature exceeds the temperature threshold, in step 670, a fault condition is declared.

[0061] In the above-described embodiments, the calculated actual temperature is compared with the baseline temperature to declare a fault condition. However, this method can also be used to indicate the type of fault condition, such as unprimed, partially primed, or primed. In those embodiments, the baseline temperature is associated with each fault condition and is, for example, the unprimed baseline temperature, the partially primed baseline temperature, and the primed baseline temperature. The calculated actual temperature can be compared with these baseline temperatures to declare a specific fault condition. This enables on-site monitoring of the heat exchanger.

[0062] After a fault condition is declared, some embodiments further include providing a visual or audible indication of the fault condition. For example, in some embodiments, an alarm can be sounded. In some embodiments, a light can blink or turn yellow. In other embodiments, words such as "fault condition" are displayed on a graphical user interface. In embodiments that indicate the type of fault condition, words such as "unprimed", "partially primed", "primed" can be displayed on the graphical interface. In other embodiments, other indicators can also be used to indicate the type of fault condition. In some embodiments, when indicating a fault condition, the method further includes automatically shutting off the heat exchanger. In still other embodiments, the method further includes sending a signal to downstream equipment. In some embodiments, the method further includes shutting off downstream equipment.

[0063] Method for detecting abnormal operating conditions of a heat exchanger: Current and temperature thresholds In some embodiments, both of these methods are used. In some embodiments, if a fault condition is detected by one method, the fault condition is declared. In other embodiments, if a fault condition is detected by both methods, the fault condition is declared.

[0064] System for detecting abnormal operating conditions of a heat exchanger Other embodiments of the present disclosure are directed to a system for detecting a fault condition of a heat exchanger. In some embodiments, the system includes a heat exchanger, a drive circuit having a current measurement element, a processor, and a graphical display.

[0065] The heat exchanger is configured to heat or cool a fluid. The heat exchanger is not limited. For example, the heat exchanger can be any type of heater having a resistive heating element. In a preferred embodiment, the heat exchanger is a cleaning liquid heater configured to heat a cleaning liquid. In other embodiments, the heat exchanger can be a thermoelectric device that uses the Peltier effect to cool a fluid. In such embodiments, the abnormal operating conditions can be detected as described above using the change in the required current relative to the baseline or the estimated change in the Peltier coefficient relative to a pre-calibrated reference value.

[0066] The drive circuit is configured to drive the heat exchanger. The drive circuit must include a current measurement element, but is otherwise not limited. In some embodiments, the drive circuit is supplied by a pair of switching transistors within an H-bridge circuit. In other embodiments, a full H-bridge circuit is used to drive two heat exchanger units simultaneously and independently.

[0067] In a preferred embodiment, the heat exchanger is driven using a PWM drive consisting of a half H-bridge circuit. In some embodiments, the PWM control signal controls the switching of the transistor, and the switching speed is determined by the duty cycle calculated by the controller. In some embodiments, a comparator having other elements such as a sawtooth input can also be used to generate the PWM output.

[0068] The drive circuit includes a current measurement element that measures the current passing through the circuit and thus through the heat exchanger. The current measurement element is not limited. The current measurement element can be any element that measures current. In a preferred embodiment, the current measurement element is a sense resistor.

[0069] As shown in FIG. 3, in some embodiments, the heat exchanger 330 is driven using a half H-bridge circuit to the PWM drive 320. The circuit 300 can have one end connected to the +V terminal and the other end connected to ground 301. The circuit 300 can also include a pair of transistors 315e and 315f, a load (heat exchanger 330) between these transistors, and a sense resistor 321. In some embodiments, these elements are connected in series.

[0070] In some embodiments, a PWM drive is not required. In some embodiments, voltage control other than PWM can be used. In some embodiments, the voltage control other than PWM is simple on / off or fuzzy control, and the DC voltage source is simply turned "on" or "off" by the controller according to the error between the baseline current and temperature and the actual current and temperature.

[0071] In some embodiments, the processor is configured to implement the methods described herein.

[0072] Some embodiments further include a graphical display. In some embodiments, when a fault condition of the heat exchanger is detected, the graphical display can display a warning to the user indicating that the fault condition has been declared. In some embodiments, the screen displays the phrase "fault condition".

[0073] FIG. 7 is an embodiment of a system 700 for detecting a fault condition of a heat exchanger. In this embodiment, the heat exchanger 730 has at its outlet a temperature sensor 731 configured to communicate the actual temperature of the fluid leaving the heat exchanger 730 to the processor 740, as shown by line 762. The processor 740 is configured to communicate this information to the control system 710, and the control system 710 determines a current command 765 based on that information and transmits it to the PWM drive 720 to drive the heat exchanger 730. The processor 740 is also configured to communicate a setpoint temperature to the control system 710, as shown by line 764.

[0074] In this embodiment, the PWM drive 720 that drives the heat exchanger 730 has a sense resistor 721. The sense resistor 721 senses the current passing through the PWM drive 720 (and thus through the heat exchanger 730) and is configured to communicate that information to the control system 710 as indicated by line 761. The control system then communicates that information to the processor 740 as indicated by line 763. According to the method described above, the processor 740 uses that information to determine whether a fault condition should be declared. When a fault condition is declared, the processor 740 is configured to communicate with the graphical display 750 to provide an indication that a fault condition exists.

[0075] Computer program product Other embodiments of the present disclosure are directed to a computer program product for detecting a fault condition of a heat exchanger. In some embodiments, the computer program product includes a computer-readable storage medium having program instructions embodied therewith for causing a processor to execute the methods described herein.

[0076] FIG. 8 shows an exemplary computing environment 800 in which embodiments of the present invention can be implemented. The computing environment 800 can include a computer system 810, which is an example of a computing system in which embodiments of the present invention can be implemented. Computers and computing environments such as the computer system 810 and the computing environment 800 are known to those of ordinary skill in the art and are therefore described briefly herein.

[0077] As shown in FIG. 8, computer system 810 can include a communication mechanism such as bus 821, or other communication mechanisms for communicating information within computer system 810. Computer system 810 further includes one or more processors 820 coupled by system bus 821 to process information. Processor 820 can include one or more central processing units (CPUs), graphical processing units (GPUs), or any other processors known in the art.

[0078] Computer system 810 also includes system memory 830 coupled to bus 821 to store information and instructions for execution by processor 820. System memory 830 can include computer-readable storage media in the form of volatile and / or nonvolatile memory, such as read only memory (ROM) 831 and / or random access memory (RAM) 832. System memory RAM 832 can include other dynamic storage devices (e.g., dynamic RAM, static RAM, and synchronous DRAM). System memory ROM 831 can include other static storage devices (e.g., programmable ROM, erasable PROM, and electrically erasable PROM). In addition, system memory 830 can be used to store temporary variables or other intermediate information during execution of instructions by processor 820. ROM 831 can store basic input / output system 833 (BIOS) that contains basic routines that help to transfer information between elements within computer system 810 during startup, for example. RAM 832 can contain data and / or program modules that are immediately accessible to and / or presently being operated on by processor 820. System memory 830 can also include, for example, operating system 834, application programs 835, other program modules 836, and program data 837.

[0079] Computer system 810 also includes a disk controller 840 coupled to bus 821 to control one or more storage devices for storing information and instructions, such as magnetic hard disk 841 and removable media drive 842 (e.g., floppy disk drive, compact disk drive, tape drive, and / or solid state drive). The storage devices can be added to computer system 810 using an appropriate device interface (e.g., Small Computer System Interface (SCSI), Integrated Device Electronics (IDE), Universal Serial Bus (USB), or FireWire).

[0080] Computer system 810 can also include a display controller 865 coupled to system bus 821 to control a display or monitor 866, such as a cathode ray tube (CRT) or liquid crystal display (LCD), to display information to a user of the computer. Computer system 810 includes a user input interface 860 and one or more input devices, such as keyboard 862 and pointing device 861, to interact with a user of the computer and provide information to processor 820. Pointing device 861 can be, for example, a mouse, trackball, or pointing stick for communicating direction information and command selections to processor 820 and controlling movement of a cursor on display 866. Display 866 can provide a touch screen interface that enables input for supplementing or replacing the communication of direction information and command selections by pointing device 861.

[0081] In response to one or more sequences of one or more instructions stored in a memory, such as system memory 830, being executed by a processor 820, computer system 810 can perform part or all of the processing steps of embodiments of the present invention. Such instructions can be read into system memory 830 from another computer-readable medium, such as a hard disk 841 or a removable media drive 842. The hard disk 841 can store one or more data stores and data files used by embodiments of the present invention. The data store contents and data files can be encrypted to improve security. The processor 820 can also be used in a multi-processing arrangement to execute one or more sequences of instructions stored in system memory 830. In alternative embodiments, instead of software instructions, or in combination with software instructions, hard-wired circuitry can be used. Accordingly, embodiments are not limited to any particular combination of hardware circuitry and software.

[0082] As described above, computer system 810 can include at least one computer-readable medium or memory that holds instructions programmed by the embodiments provided herein and that houses data structures, tables, records, or other data described herein. As used herein, the term “computer-readable medium” refers to any medium that participates in providing instructions to a processor 820 for execution. The computer-readable medium can take many forms, including but not limited to non-volatile media, volatile media, and transmission media. Non-limiting examples of non-volatile media include optical disks such as hard disk 841 or removable media drive 842, solid state drives, magnetic disks, and magneto-optical disks. Non-limiting examples of volatile media include dynamic memory such as system memory 830. Non-limiting examples of transmission media include coaxial cables, copper wire, and fiber optics including the wires that make up bus 821. The transmission media can also take the form of acoustic or light waves, such as those generated during radio wave and infrared data communications.

[0083] Computing environment 800 can further include a computer system 810 that operates in a network environment using a logical connection to one or more remote computers, such as remote computing device 880. Remote computing device 880 can be a personal computer (laptop or desktop), mobile device, server, router, network PC, peer device, or other common network node and typically includes many or all of the elements described above in relation to computer system 810. When used in a network environment, computer system 810 can include a modem 872 for establishing communications via a network 871 such as the Internet. Modem 872 can be connected to system bus 821 via user network interface 870 or another suitable mechanism.

[0084] Network 871 can be any network or system generally known in the art, including the Internet, an intranet, a local area network (LAN), a wide area network (WAN), a metropolitan area network (MAN), a direct or serial connection, a cellular phone network, or any other network or medium capable of facilitating communication between computer system 810 and other computers (e.g., remote computing device 880). Network 871 can be wired, wireless, or a combination thereof. The wired connection can be implemented using Ethernet, Universal Serial Bus (USB), RJ-11, or any other wired connection generally known in the art. The wireless connection can be implemented using Wi-Fi, WiMAX, and Bluetooth, infrared, cellular networks, satellites, or any other wireless connection method generally known in the art. Additionally, some networks can function alone or can communicate with each other to function to facilitate communication within network 871.

[0085] As described herein, various systems, subsystems, agents, managers, and processes can be implemented using hardware components, software components, and / or combinations thereof.

[0086] Although the present invention has been described with reference to exemplary embodiments, the present invention is not limited thereto. It will be understood by those skilled in the art that numerous changes and modifications can be made to the preferred embodiments of the present invention, and such changes and modifications can be made without departing from the true spirit of the present invention. Accordingly, the appended claims are intended to be construed to include all such equivalent variations that fall within the true spirit and scope of the present invention.

Claims

1. A method for detecting abnormal operating conditions of a heat exchanger, comprising: determining an actual current passing through the heat exchanger; using the actual current to indicate abnormal operating conditions; declaring a fault condition, wherein the method further comprises determining a baseline current, and the step of using the actual current to indicate abnormal operating conditions includes comparing the baseline current with the actual current, and the step of comparing the baseline current with the actual current includes: normalizing the actual current; calculating a difference between the normalized actual current and the baseline current; determining that the difference is less than 0; determining a baseline signal-to-noise ratio; calculating an actual signal-to-noise ratio; comparing the actual signal-to-noise ratio with the baseline signal-to-noise ratio; determining that the actual signal-to-noise ratio is greater than the baseline signal-to-noise ratio.

2. A method for detecting abnormal operating conditions of a heat exchanger, comprising: determining an actual current passing through the heat exchanger; using the actual current to indicate abnormal operating conditions; declaring a fault condition, wherein the step of using the actual current to indicate abnormal operating conditions includes: determining a baseline temperature; determining a reference temperature resistance of the heat exchanger and a thermoelectric resistance coefficient of the heat exchanger; calculating an actual temperature of the heat exchanger using the actual current, the reference temperature resistance of the heat exchanger, and the thermoelectric resistance coefficient of the heat exchanger; determining that the actual temperature of the heat exchanger is greater than the baseline temperature.

3. The method according to claim 2, wherein the baseline temperature represents a specific type of abnormal operating condition, and declaring a fault condition further includes declaring a specific type of abnormal operating condition.

4. The method according to claim 3, wherein the type of abnormal operating condition is selected from the group consisting of unprimed, partially primed, and primed.

5. A system for detecting abnormal operating conditions of a heat exchanger, comprising: a heat exchanger; a drive circuit configured to supply power to the heat exchanger, the drive circuit including a current measurement device configured to measure a current passing through the heat exchanger; a processor, wherein the processor is configured to determine an actual current passing through the heat exchanger, use the actual current to indicate abnormal operating conditions, declare a fault condition. The system including a graphical display configured to display an indication that a failure state has been declared, wherein the processor, for the process of indicating abnormal operating conditions using the actual current: determines a baseline temperature; determines a reference temperature resistance of the heat exchanger and a thermoelectric resistance coefficient of the heat exchanger; calculates an actual temperature of the heat exchanger using the actual current, the reference temperature resistance of the heat exchanger, and the thermoelectric resistance coefficient of the heat exchanger; and is further configured to determine that the actual temperature of the heat exchanger is greater than the baseline temperature. **Claim 6** The step of determining a reference temperature resistance of the heat exchanger and a thermoelectric resistance coefficient of the heat exchanger: operates the heat exchanger under a plurality of duty conditions; measures the current and temperature for each of the plurality of duty conditions; The system according to claim 5, wherein the processor is further configured to calculate a reference temperature resistance of the heat exchanger and a thermoelectric resistance coefficient of the heat exchanger using the measured current and temperature.

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