JPH0348442B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for measuring the thickness of a layer of ice that grows on the surface of a freezing tube. This invention relates to an ice layer thickness measuring device that can continuously measure the ice layer thickness by increasing and decreasing the ice layer thickness according to the thickness of the ice layer.

For example, in a cooling water cooling device called an ice bank, the thickness of the ice layer that grows on the cooling surface is continuously monitored, and this is used to control the ice layer thickness at a fixed value or to prevent ice formation during economical operation. This requires control of the layer thickness and calculation of the average ice layer thickness for continuous measurement of the amount of cold heat stored in the ice bank tank. At most, measurements were performed using a mechanical mechanism that brought a stylus into contact with the frozen surface intermittently. This is due to the adverse environmental conditions surrounding the ice bank, such as temperature, humidity, structure, etc., which left many problems with the measuring device.

The present invention was made in view of this point, and the electrostatic capacitance between the conductive rod and the water to be cooled is reduced by freezing through the insulation film between the conductive rod and the water to be cooled. By increasing and decreasing according to the thickness of the layer, it is possible to continuously measure the thickness of the frozen layer.

Figure 1 is a schematic diagram showing the principle, 1 is a freezing tube,
Reference numeral 2 denotes an electrode rod erected on the surface of the freezing tube, and the details of the electrode rod 2 are shown in FIG. Reference numeral 3 denotes a conductive rod, the surface of which is covered with a thin insulating film 4 having a high dielectric constant, and constitutes the electrode rod 2. The apparent thermal conductivity of the conductive rod 3 or the electrode rod 2 made of a film covering its surface must be designed to a value close to the thermal conductivity of ice, 2 K.cal/m, h, °C. It is. If the conductive rod is made of copper, the thermal conductivity of copper is approximately 335K.cal/
mh°C, and in the early stages of freezing, it is difficult to cool the water due to the temperature gradient of the water to be cooled 10 surrounding the freezing pipe 1, and the freezing surrounding the electrode rod 2 is delayed, and in the final stage of freezing. Since the thermal conductivity of the electrode rod 2 is higher than that of ice, freezing occurs early and does not correspond to the growth and melting of a true frozen surface.For this purpose, a metal rod with low thermal conductivity or This is a resin rod whose surface is plated to give it electrical conductivity. Next, the length of the electrode rod 2 must be constant enough to be immersed in the water to be cooled 10, and this is due to changes in the surface of the water to be cooled 10. This is to avoid being influenced by the true capacitance with respect to thickness.

Next, if the ideal counter electrode 10' is an electrical simulation of the cooled water 10 in contact with the insulated conductor 6 including the lead wire 5 connected to the electrode rod 2, then the cooled water 1
0, the conductive rod 3, and the core wire 5, and when an AC voltage is applied to both 3, 5, and 10' from the AC power supply 9, an AC current flows through the capacitance, and this can be measured with an indicator 8 such as an ammeter. In this case, due to the growth of the frozen layer 11, the electrode rod 2 is gradually buried therein. This results in a reduction in the opposing area of the counter electrode 10' facing the electrode rod 2, and a change in capacitance, making it possible to display the ice layer thickness from the value of the alternating current passing through this. It is well known that the instruction for decreasing the growth of the ice layer thickness can be made in the same direction by the electric bridge output as the standard voltage, so the explanation will be omitted.

The change in capacitance with respect to the ice layer thickness is linear in principle, which is important and optimal for measuring the ice layer thickness.

FIG. 3 is a cross-sectional view of the electrode rod 2 installed obliquely on the surface of the freezing tube 1, and the water to be cooled is energized by the ground electrode 12. If the mounting angle between the electrode rod 2 and the freezing tube 1 is θ, the thickness of the frozen layer is h, and the corresponding length of the electrode rod is l, then l/h = tan θ, and the change in the frozen layer thickness (h). By lengthening the electrode rod (l) when the amount of light is small, the sensitivity can be increased, which is useful for improving measurement accuracy.

FIG. 4 is a schematic diagram showing the measurement of the average ice layer thickness on one surface of the ice tube. A plurality of the electrode rods 2 21, 22, 23, . . . are arranged in parallel at necessary locations on the freezing tube 1. Generally, the uniformity of the thickness of the frozen layer 11 on the surface of the cooling pipe 1 depends on the flow of the refrigerant in the cooling pipe 1, the flow state of the water to be cooled 10 surrounding the cooling pipe 1, and various other factors. affected. In particular, when freezing and melting occurs repeatedly in an ice bank and the latent heat thereof is utilized, it is necessary to constantly grasp the amount of heat stored as the latent heat of the ice and control the freezing state. For this purpose, the sum of the electric signals from the plurality of electrode rods 21, 22, 23- is calculated and averaged, or each signal is weighted and the average value is calculated by the calculator 1.
3, the total amount of ice formation or the total amount of heat storage can be determined by causing the indicator 8 to give an instruction.

As described above, the present invention enables the measurement of the thickness of the frozen layer on the surface of the freezing tube by using a method that approximates the thermal conductivity of ice, and which connects the electrode rod coated with an insulating film with a high dielectric constant and the water to be cooled. Since it utilizes the fact that the capacitance between It is indispensable for automated operation and management of ice banks and other facilities.

[Brief explanation of drawings]

Figure 1 is a schematic diagram showing the measurement principle of the present invention, Figure 2 is a cross-sectional view of the electrode rod, Figure 3 is a schematic diagram of the attachment of the electrode rod to improve sensitivity, and Figure 4 is a diagram showing the measurement of the average ice layer thickness. Schematic diagram. DESCRIPTION OF SYMBOLS 1... Cooling pipe, 2... Electrode rod, 8... Ice layer thickness indicator, 9... AC power source, 10... Water to be cooled, 11... Ice layer, 12... Ground electrode, 13... Arithmetic unit.

Claims (1)

[Scope of Claims] 1. An electrode rod for measuring ice layer thickness whose apparent thermal conductivity approximates that of ice, which is a conductive rod whose surface is coated with a thin film having a large dielectric constant property. The frozen layer is formed by forming an electrode rod, standing the electrode rod on the surface of the freezing tube, immersing it in water to be cooled, and increasing or decreasing the capacitance between the electrode rod and the conductive rod according to the thickness of the frozen layer. An ice layer thickness measuring device characterized by measuring thickness. 2. The ice layer thickness measuring device according to claim 1, wherein the electrode rod is attached to the surface of the ice tube at an angle to measure the ice layer thickness. 3. Claim 1, characterized in that a plurality of the electrode rods are arranged in parallel at necessary locations on the surface of the freezing tube, and the amount of cold heat storage is calculated based on the average frozen layer thickness and the total amount of frozen ice in the freezing tank. The ice layer thickness measuring device described in Section 1.