Accurate measurement and calculation control method for descaling of heating body

Abstract

The invention discloses an accurate measurement and calculation control method for descaling of a heating body, which is characterized in that the temperature difference rise of membrane outlet water of the heating body after scaling is utilized to reversely deduce whether scaling occurs or not and the accurate measurement and calculation method of the thickness of the scale after scaling is adopted, and the method adopted by the method is used for monitoring and the formula is used for calculation, so that the scale is accurately measured and calculated. According to the method, the scale on the thick film heating body is accurately measured, calculated and controlled, whether the scale is formed or not is strictly monitored, real-time reminding or alarming is carried out, the overheating condition is avoided, the use risk in the heating process is reduced, and the safety and intelligent control of thick film heating body type water supply equipment are further improved.

Description

[Technical field]

[0001] The present invention relates to the technical field of thick film heaters, and in particular to a method for accurately measuring and controlling the descaling of thick film heaters. [Background technology]

[0002] In the relevant fields of drinking water equipment in my country, rapid heating technology has been favored by the general public.

[0003] However, the rapid heating technology currently on the market achieves water output at different temperatures by coordinating the power of the heating body with the flow rate of system water. Although it solves the problem of quickly heating drinking water, as scale is generated during the heating process, the inside of the heating body and the water channels will be blocked. Finally, the surface of the heating body will have high temperature, and the whole machine will eventually fail or cause serious accidents such as fire.

[0004] Currently, the industry's anti-scaling technology is to manually set the water quality. After the heated water volume reaches the set value, it is directly prohibited from use. However, combined with actual usage surveys, it is clear that this method has large deviations. First of all, the water quality parameters set by the user may be wrong, and the factors that form scale are extremely complex. Water hardness, TDS value, water flow rate during heating, water pH, etc. will affect the speed of scale formation. Therefore, false alarms often occur, which affects the user experience. [Summary of the invention]

[0005] The present invention aims at the problems existing in the prior art. The present invention provides a method for accurately measuring whether scaling has occurred and the thickness of scale after scaling by utilizing the increased temperature difference of the membrane outlet water of the heating body after scaling. The method adopted by the method is used for monitoring and the formula is used for calculation to realize the accurate measurement and control method of scaling on the thick film heating body. The scaling is closely monitored, and real-time reminders or alarms are given to avoid overheating, reduce the risk of use during the heating process, and further improve the safety and intelligent control of thick film heating body water supply equipment.

[0006] According to the existing multi-layer wall heat conduction physical model, please refer to the attached Figure 1 The figure is a schematic diagram of the multi-layer wall heat conduction physical model. We obtain the calculation method of the temperature difference generated by the thick film heating body from the inner layer to the outer layer of the film, establish a multi-layer wall heat conduction physical model, and use the formula derived from the model to calculate the temperature difference:

[0007] Heat conduction formula for n-layer cylindrical wall:

[0008]

[0009] Try substituting the reference values: The thermal resistance of a stainless steel pipe with a diameter of 15 mm and a wall thickness of 1 mm is:

[0010]

[0011] Thermal resistance of 0.15mm thick insulation layer:

[0012]

[0013] When the power P of the thick film heater is 2100W, the temperature difference ΔT1 between the inner and outer surfaces is:

[0014] ΔT1=P×R=2100×(0.01082+0.02047)=65.751℃

[0015] If the water temperature measured at the outlet is 95°C, then the film temperature at the outlet is:

[0016] 95+66=161℃

[0017] It can be understood that if the temperature difference between the inner and outer surfaces of the heating body itself needs to reach 65.751°C, and at the same time the outlet water temperature needs to reach 95°C, then the membrane temperature needs to reach at least 161°C.

[0018] If scale is superimposed, the average thickness of the scale is taken as 0.1mm, and the thermal conductivity of the reference scale is 2% to 5% of that of stainless steel. The thermal conductivity of #304 stainless steel is selected as 17, that is, the thermal conductivity of the scale is 0.34 to 0.85, and the middle value of 0.55 is taken. In fact, there are gaps in the scale, and the thermal conductivity will increase.

[0019] The thermal resistance of scale under the above conditions is calculated as:

[0020]

[0021] Based on the thermal resistance of the thick film heater itself and the thermal resistance of the scale, the temperature difference ΔT2 generated by the thermal resistance of the thick film heater and the scale as a whole when the power P is 2100W is calculated as:

[0022] ΔT2=P×R=2100×(0.01082+0.02047+0.08788)=250.257℃

[0023] Then, based on the above deduction, still taking the outlet water temperature of 95°C as an example, the membrane temperature measured at the outlet should be: 95+250=345°C.

[0024] Through the above derivation, we can understand that under fixed power, the temperature difference between the inside and outside of the heating body itself is ΔT1, and the temperature difference after the scale is superimposed on the heating body is ΔT2. The water temperature can be obtained through real-time detection. Since ΔT1 and ΔT2 cannot be directly measured, they can only be obtained indirectly by subtracting the outlet water temperature from the membrane temperature at the outlet, which can be directly measured. At this time, we define a concept: membrane outlet water temperature difference, that is, the membrane outlet water temperature difference is obtained by the difference between the membrane temperature that can be directly measured and the outlet water temperature that can be directly measured. So we can understand the membrane temperature difference of the heating body to judge whether it is scaling.

[0025] In summary: the difference in the rise in the membrane temperature of the heating body after scaling can be used to reversely infer whether scaling has occurred and the thickness of the scale after scaling. Scaling detection can be achieved through the above formula and calculation.

[0026] The invention relates to a precise measurement and control method for descaling a heating element, characterized in that it comprises the following steps:

[0027] Step 1: a film temperature thermometer is arranged on the surface of the thick film heater to collect the film surface temperature T1 of the thick film heater; a water outlet thermometer is arranged at the water outlet to collect the water temperature T2 at the water outlet;

[0028] Step 2: Calculate the temperature difference ΔT. The temperature difference at this time is the temperature difference of the membrane outlet water from the inner surface of the heating body to the outer surface of the heating body / heating body + scale, excluding the water temperature that needs to be reached;

[0029] At this time, the temperature difference ΔT=T1-T2

[0030] Step 3: The system detects and judges whether the heating element is used for the first time or has been descaled. If yes, the system's membrane outlet water temperature difference is re-recorded. If no, the initial temperature difference without scaling retained in the system is used as the membrane outlet water temperature difference ΔT0.

[0031] Step 4: If it is the first time to use or the system has been descaled, re-record the system's membrane outlet water temperature difference ΔT0;

[0032] Step 5: Test the temperature difference of the water at the actual water outlet to keep the outlet water temperature consistent with the set temperature. When the inlet water temperature remains unchanged, maintain the water temperature difference for 5 seconds. Record the actual tested membrane temperature as T1 and the outlet water temperature as T2, and obtain the temperature difference ΔT between the two.

[0033] Step 6: Compare the temperature difference ΔT obtained from the actual test and the membrane outlet water temperature difference ΔT0;

[0034] Step 7: Determine whether to issue a descaling alarm based on the comparison results.

[0035] The alarm reminder sets three working states:

[0036] When ΔT-ΔT0<2℃, the indicator light turns green and the whole machine works normally.

[0037] When 2℃≤ΔT—ΔT0<8℃, the indicator light turns yellow and the whole machine works normally.

[0038] When ΔT-ΔT0≥8℃, the indicator light turns yellow and the whole machine is prohibited from working;

[0039] Furthermore, the control method also has a false alarm prevention step. If the system obtains an alarm prompt that the entire machine is prohibited from working, five consecutive precise tests and judgments are performed. If the alarm standard is met five times in a row, the alarm conclusion is confirmed and the entire machine is prohibited from working.

[0040] In step three, the system needs to make a judgment after detection. Due to the influence of manufacturing tolerance, boiling point adaptation and other factors during the production process of the heating body, the tolerance ΔT0 of the initial membrane temperature and the initial water outlet temperature will have errors, resulting in inaccurate conclusions of scale detection and prone to false alarms. Therefore, a self-learning calibration system needs to be set in the system. Therefore, there are judgment step three and re-assignment step four.

[0041] The present invention relates to a precise measurement and control method for descaling a heating body. Based on a multi-layer wall heat conduction model, the method uses the change in the temperature difference on the membrane surface caused by scaling on the surface to accurately detect whether scale has been generated on the surface of the heating body, and uses the membrane temperature rise of the heating body to evaluate the thickness of the scale. The measurement method is accurate and precise control is achieved. Scaling is closely monitored, and real-time reminders or alarms are given to avoid overheating, reduce the risk of use during the heating process, and further improve the safety and intelligent control of thick film heating body water supply equipment.

Brief Description of the Drawings

[0042] Figure 1 It is a schematic diagram of the multi-layer wall heat conduction physical model involved in the theoretical basis of the present invention;

[0043] Figure 2 It is a schematic diagram of the temperature detection setting in the accurate measurement and control method for descaling a heating body involved in the present invention;

[0044] Figure 3 It is a flow chart of the accurate measurement and control method for descaling a heating body designed in the present invention;

[0045] in:

[0046] L1: membrane temperature thermometer, L2: outlet water thermometer. [Specific implementation method]

[0047] The present invention will be described in detail below in conjunction with the accompanying drawings and embodiments, examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0048] In the description of the present invention, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0049] Please refer to the attached Figure 1 , which is a schematic diagram of a multi-layer wall heat conduction model, and the thick film heating element involved in the present invention is obviously such a heat conduction heating element with a certain layer thickness.

[0050] Please refer to the attached Figure 2 , which shows the locations of the film temperature thermometer and the outlet water temperature thermometer.

[0051] A precise measurement and control method for heating element descaling, please refer to the attached Figure 3 , which includes the following steps:

[0052] Step 1: a film temperature thermometer L1 is set on the surface of the thick film heater to collect the film surface temperature T1 of the thick film heater; a water outlet thermometer L2 is set at the water outlet to collect the water temperature T2 of the water outlet;

[0053] First of all, it should be noted that the temperature that can be detected is the temperature. The temperature detected by the film temperature thermometer L1 is the temperature reached by the surface of the thick film heating body or the surface of the thick film heating body and the scale attached to the surface. The water outlet thermometer is set at the water outlet to detect the temperature of the heated water.

[0054] Step 2: Calculate the temperature difference ΔT. The temperature difference at this time is the temperature difference of the membrane outlet water from the inner surface of the heating body to the outer surface of the heating body / heating body + scale, excluding the water temperature that needs to be reached;

[0055] At this time, the membrane outlet water temperature difference ΔT=T1-T2

[0056] Step 3: The system detects and judges whether the heating element is used for the first time or has been descaled. If yes, the system's membrane outlet water temperature difference is re-recorded. If no, the initial temperature difference without scaling retained in the system is used as the membrane outlet water temperature difference ΔT0.

[0057] Step 4: If it is the first time to use or the system has been descaled, re-record the membrane outlet water temperature difference ΔT0 of the system;

[0058] Step 5: Test the temperature difference of the water at the actual water outlet to keep the outlet water temperature consistent with the set temperature. When the inlet water temperature remains unchanged, maintain the water temperature difference for 5 seconds. Record the actual tested membrane temperature as T1 and the outlet water temperature as T2, and obtain the temperature difference ΔT between the two.

[0059] Step 6: Compare the temperature difference ΔT obtained from the actual test and the membrane outlet water temperature difference ΔT0;

[0060] Step 7: Determine whether to issue a descaling alarm based on the comparison results.

[0061] The alarm reminder sets three working states:

[0062] When ΔT-ΔT0<2℃, the indicator light turns green and the whole machine works normally.

[0063] When 2℃≤ΔT—ΔT0<8℃, the indicator light turns yellow and the whole machine works normally.

[0064] When ΔT-ΔT0≥8℃, the indicator light turns yellow and the whole machine is prohibited from working;

[0065] Furthermore, the control method also has a false alarm prevention step. If the system obtains an alarm prompt that the entire machine is prohibited from working, five consecutive precise tests and judgments are performed. If the alarm standard is met five times in a row, the alarm conclusion is confirmed and the entire machine is prohibited from working.

[0066] In step three, the system needs to make a judgment after detection. Due to the influence of manufacturing tolerances, boiling point adaptation and other factors during the production process of the heating body, there will be errors in the tolerance ΔT0 of the initial membrane temperature and the initial water outlet temperature, resulting in inaccurate conclusions on scale detection and prone to false alarms. Therefore, a self-learning calibration system needs to be set in the system, which leads to judgment step three and reassignment step four.

[0067] The present invention relates to a precise measurement and control method for descaling a heating body. Based on a multi-layer wall heat conduction model, the method uses the change in the temperature difference on the membrane surface caused by scaling on the surface to accurately detect whether scale has been generated on the surface of the heating body, and uses the membrane temperature rise of the heating body to evaluate the thickness of the scale. The measurement method is accurate and precise control is achieved. Scaling is closely monitored, and real-time reminders or alarms are given to avoid overheating, reduce the risk of use during the heating process, and further improve the safety and intelligent control of thick film heating body water supply equipment.

[0068] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention is disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this profession can make some changes or modifications to equivalent embodiments of equivalent changes by using the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent changes and modifications made to the above embodiments according to the technology of the present invention are within the scope of the technical solution of the present invention without departing from the content of the technical solution of the present invention.

Claims

1. A precise measurement and control method for descaling a heating element, characterized in that: The following steps are involved: Step 1: a film temperature thermometer is arranged on the surface of the thick film heater to collect the film surface temperature T1 of the thick film heater; a water outlet thermometer is arranged at the water outlet to collect the water temperature T2 at the water outlet; Step 2: Calculate the temperature difference ∆T. The temperature difference at this time is the temperature difference of the membrane outlet water from the inner surface of the heating body to the outer surface of the heating body / heating body + scale, excluding the water temperature that needs to be reached; At this time, the temperature difference ∆T=T1-T2 Step 3: The system detects and judges whether the heating element is used for the first time or has been descaled. If yes, the system's membrane outlet water temperature difference is re-recorded. If no, the initial temperature difference without scaling retained in the system is used as the membrane outlet water temperature difference ∆T0. Step 4: If it is the first time to use or the system has been descaled, re-record the membrane outlet water temperature difference ∆T0 of the system; Step 5: Test the temperature difference of the water at the actual water outlet. Keep the outlet water temperature consistent with the set temperature. When the inlet water temperature remains unchanged, maintain the water temperature difference for 5 seconds. Record the actual tested membrane temperature as T1 and the outlet water temperature as T2, and obtain the temperature difference ∆T between the two. Step 6: Compare the temperature difference ∆T obtained from the actual test and the membrane outlet water temperature difference ∆T0; Step 7: Determine whether to issue a descaling alarm based on the comparison results. The alarm reminder sets three working states: When ∆T—∆T0 <2℃, the indicator light turns green and the whole machine works normally; When 2℃≤∆T—∆T0 <8℃, the indicator light turns yellow and the whole machine works normally. When ∆T—∆T0≥8℃, the indicator light turns yellow and the whole machine is prohibited from working.

2. According to claim 1, the precise measurement and control method for the heating element after descaling is characterized in that: The control method also has a false alarm prevention step. If the system obtains an alarm prompt that the entire machine is prohibited from working, five consecutive precise tests and judgments are performed. If the alarm standard is met five times in a row, the alarm conclusion is confirmed and the entire machine is prohibited from working.

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