JPS5915845A - Measurement of vacuum heat insulating capacity - Google Patents

Abstract

PURPOSE:To measure heat insulating capacity, by a method wherein a pipe or a box having vacuum heat insulation applied thereto and known heat conductivities is evacuated and the part thereof is heated or cooled to measure a temp. gradient. CONSTITUTION:A heater 3 is provided in a pipe 2 having vacuum heat insulation 1 and known heat conductivity while temp. sensors 5, 6 are contacted with two places of the inner wall of the pipe 2 and blind cocks 7, 8 are inlaid with both ends of the pipe 2 to evacuate the interior through a suction pipe 9. The part of the pipe 2 is heated by the heater 3 and the temp. difference of the temp. sensors 5, 6 is measured to calculate a temp. gradient to measure heat insulating capacity.

Description

Detailed Description of the Invention: In the measurement of the insulation performance of low-temperature liquefied gas appliances with vacuum insulation or multi-layer vacuum insulation, the present application installs vacuum insulation on a pipe with known thermal conductivity, and uses this pipe to radiate heat (or (cooling) fins, heat or cool one end or part of the pipe, create a vacuum inside the pipe, measure the temperature difference between two points inside the pipe at room temperature, and measure the temperature direction, thereby improving insulation performance. The present invention relates to a method for measuring vacuum insulation performance, which is characterized by the fact that it is measured.

The present application relates to a simple method for measuring the vacuum insulation performance of low-temperature liquefied gas appliances, etc., by using a heat dissipation (or cooling) fin as a model to measure the performance of the vacuum insulation method or the multilayer vacuum insulation method.

To explain an example of the embodiment shown in the figure, a heater (3) is installed inside a pipe (2) whose entire outer circumference has a vacuum cut of 1 m (+11), and temperature sensors f5 are installed at three locations on the inner wall of the pipe (2). ) (6> with a spring, etc., and connect the pipe (
2), fit the blind plug (71 (8)) to both ends of the plug (7), pull out the conductor (4) from the blind plug (7) on one side, connect it to a measuring device (not shown), and connect the blind plug (8) on the oil side. A suction pipe (9) connected to a vacuum pump (not shown) is airtightly inserted into the
It is to be opened inside the pipe (2).

With the above configuration, the present invention provides a pipe (
2) Heat a part of the suction pipe (9) using a vacuum pump.
Pipe (2) while keeping the inside of pipe (2) in a vacuum state.
A part of the pipe (2) is heated to prevent heat conduction due to the gas (air) inside, and the temperature difference between the temperature sensors (5) and (f6) is measured using a measuring device.

Furthermore, it is clear from the following equation that the temperature distribution on the heat dissipation (or cooling) fin changes depending on the heat transfer coefficient of the fin surface.

ll=to-A/Cc-LF2 L F = (Z+-Z2)//n ((1'+ i″
,,, )/(T2-'r-) )h 7747 Surface heat transfer coefficient: Thermal conductivity of fin material A: Fin cross-sectional area CC: Fin outer circumference L': Apparent fin length Z+-22 ): Distance between two temperature measurement points Ill; Temperature at measurement point 1 Tt: Temperature at measurement point 2 T - 2 ambient temperature Also, this heat transfer coefficient is a value unique to the heat insulation installed on the fin surface. Furthermore, if the thickness of this insulation is known, the thermal conductivity of this insulation can be calculated from this heat transfer coefficient.

That is, vacuum insulation or multilayer vacuum insulation is installed on the surface of the pipe (2), etc., a part or one end of the pipe (2) is heated or cooled, the temperature is measured at two appropriate points, and the values are calculated using the above formula. The insulation performance can be calculated by substituting .

Note that this method cannot be applied when using urethane insulation, glass foam insulation, etc. instead of vacuum insulation, as there is a lot of heat transfer through the heating material in the same direction as the fins, but it is important to know the rough performance. is possible.

As mentioned above, the present application creates a vacuum inside a pipe or box with vacuum insulation on the outer periphery and a known thermal conductivity, heats or cools one end surface or part of the pipe or box, and then heats or cools the pipe or box at room temperature. It is characterized by measuring the temperature at two points on the box and measuring the temperature direction based on the temperature difference to measure the insulation performance, so that the desired purpose can be well achieved.

[Brief explanation of the drawing]

The figure is a sectional view showing an embodiment of the present application. Patent applicant: Toyo Sanso Co., Ltd.

Claims (1)

[Claims] (1) Create a vacuum inside a pipe or box with a known thermal conductivity that has been vacuum-insulated on its outer periphery, heat or cool one end surface or part of the pipe or box, and then heat or cool two points on the pipe or box at room temperature. A method for measuring vacuum insulation performance, characterized in that the insulation performance is measured by measuring the temperature of and measuring the temperature orientation based on the temperature difference.