JPH0517365U - Water pipe - Google Patents

Abstract

(57) [Summary] [Purpose] The shape retention and strength are the same as before.
In addition, a water pipe that can surely prevent the pipe from bursting due to freezing is obtained. [Composition] A water pipe having a deformable member 3 formed in a tubular shape and having a shape-memory polymer material whose shape changes with freezing temperature, built in the pipe.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 This invention relates to means for preventing rupture due to freezing of water pipes such as water pipes and heat exchangers.

[0002]

[Prior Art]

 As a conventional means for preventing the water pipe from bursting due to freezing, a rubber coating is applied to the inside of the pipe, or a pipe is made of a stretchable material.

[0003]

[Problems to be solved by the device]

 The conventional means for preventing rupture due to freezing of the water pipe is as described above, but the rubber coating is not effective unless it is made considerably thick. In addition, there is a problem that the tube made of stretchable material does not retain its shape and its strength is low.

The present invention has been made in order to solve the above problems, and has a novel means that has the same shape-retaining property and strength as the conventional one, and can reliably prevent the rupture of a pipe due to freezing. The purpose is to get.

[0005]

[Means for Solving the Problems]

 The water pipe according to the present invention is one in which a deformable member formed in a tubular shape with a shape memory polymer material whose shape changes at freezing temperature is built in the pipe.

[0006]

[Action]

 The deformable member formed in a tubular shape with the shape memory polymer material built into the water pipe of this invention has a small internal volume of the tubular member of the deformable member when the water temperature in the pipe decreases and the freezing temperature is reached. Transform to become. This deformation absorbs the volume expansion associated with the phase change from water to ice due to freezing. This prevents the pressure of volume expansion due to freezing from being applied to the pipe and prevents the pipe from bursting. When the temperature rises from a low temperature to the temperature at which ice melts, the shape of the deformable member is restored.

[0007]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view of a heat transfer tube of a heat exchanger, (A) shows a state when water is a liquid, and (B) shows a state when water freezes to become ice. This heat transfer tube has a double tube structure in which an inner tube 2 is provided inside an outer tube 1. The outer tube 1 and the inner tube 2 are made of the same material as the conventional heat transfer tube. A space between the outer pipe 1 and the inner pipe 2 is a cooling medium passage 5 through which a cooling medium such as a refrigerant or brine flows, and an inner portion of the inner pipe 2 is a water passage 6 through which water to be heat-exchanged flows. A deformable member 3 is provided inside the inner tube 2. The deformable member 3 is made of a shape memory polymer material such as a polyurethane polymer material, as shown in FIG. 1 (A), and the main body has a tubular shape with a circular cross section at room temperature. A plurality of protrusions are formed so as to be in contact with the inner surface of the inner pipe 2, and are manufactured to be supported by the inner pipe 2. The hollow portion 4 in the tubular main body portion of the deformable member 3 may be filled with air, but it is also possible to put another substance or flow some fluid as described later. The deformable member 3 has a circular cross-sectional shape as shown in FIG. 1A at normal temperature, and when the temperature drops to a specific temperature region, for example, 0 degrees Celsius, the main body having the circular cross-section has, for example, the shape shown in FIG. As shown in (B), the hollow portion 4 is deformed into a star shape, and the cross-sectional area of the cavity 4 in the deformable member 3 is reduced. When the temperature rises above 0 degrees Celsius, the star shape shown in FIG. 1 (B) returns to the circular shape shown in FIG. 1 (A).

Next, the operation will be described. Refrigerant flow path 5 between the outer tube 1 and the inner tube 2 is made to flow a heat working medium such as a refrigerant and a line, and water is flowed at a water flow path 6 between the inner tube 2 and the tubular main body of the deformable member 3. The heat is exchanged between the refrigerant and water through the tube wall of the inner tube 2. The tubular body of the deformable member 3 has a circular cross section as shown in FIG. 1 (A) at a temperature exceeding 0 degrees Celsius. That is, if the temperature of the water flowing in the water flow path 6 is higher than 0 degrees Celsius, the tubular main body of the deformable member 3 has a circular cross section. However, since the deformable member 3 is made of the shape memory polymer material, when the temperature of the water in the water flow path 6 decreases to, for example, 0 degrees Celsius or less, the main body of the deformable member 3 having a circular cross section is For example, as shown in FIG. 1 (B), the cross-sectional area of the hollow portion 4 inside the deformable member 3 is reduced due to the deformation into a star shape, the volume of the hollow portion 4 is decreased, and the volume of the water channel 6 is relatively increased. Will increase. Therefore, even if the water in the water flow path 6 freezes below 0 degrees Celsius and undergoes a phase change from water to ice and the volume increases by about 10%, the volume increase is accounted for by the cylindrical shape of the deformable member 3. Compensation is made by increasing the volume in the water channel 6 due to the deformation of the main body. As a result, the pressure of ice that freezes and expands is applied to the inner pipe 2, and the inner pipe 2 is prevented from bursting. When the temperature of the ice in the water channel 6 rises to 0 degrees Celsius or higher and the ice in the water channel 6 becomes water, and the volume decreases due to the phase change, at the same time, the tubular main body of the deformable member 3 becomes The cross-sectional star shape shown in FIG. 1B is restored to the circular cross-sectional shape shown in FIG. The volume inside the cavity 4 increases and the volume inside the water flow path 6 decreases, which corresponds to a decrease in the volume of water.

FIG. 2 shows another embodiment. FIG. 2A is a cross-sectional view of a shell-and-tube type heat exchanger, which is used, for example, as an evaporator of a refrigerating apparatus. A plurality of deformable members 3 which are tubes are built in an outer tube 1 which is a shell. The deformable member 3 is made of a shape memory polymer material, and has the same deforming function as that of the deformable member 3 described above. For example, at 0 degrees Celsius or more, the deformed member 3 has a circular cross section as shown in the figure, and at 0 degrees Celsius or less. Transforms into an elliptical shape, for example. The space outside the deformable member 3 inside the outer tube 1 is the water flow path 6, and the space inside the deformable member 3 is the refrigerant flow path 5. The refrigerant flowing in the refrigerant flow path 5 and the water flowing in the water flow path 6 exchange heat through the pipe wall surface of the deformable member 3. When the water in the water channel 6 is liquid, the deformable member 3 has a circular cross section. When the temperature of the water in the water channel 6 decreases to ice, the volume expands. At that time, the deformable member 3 has an elliptical cross section, and the volume of the refrigerant channel 5 decreases. The volume increases. This compensates for the increase in the volume of water to ice due to freezing, and prevents the outer tube 1 from bursting.

FIG. 2B is a cross-sectional view of a water pipe or the like. A deformable member 3 made of a shape memory polymer material is built in the outer tube 1. Water flows in the space outside the deformable member 3 inside the outer tube 1 as a water flow path 6, and a compressive fluid such as air is put into the cavity 4 inside the deformable member 3. Similar to the above, the deformable member 3 is deformed at the temperature of the phase change of water and ice, the volume in the water channel 6 is changed, the volume change of water and ice is compensated, and the outer tube 1 is prevented from bursting. ..

It should be noted that, in FIG. 1, when the water in the water flow path 6 is frozen, hot water is caused to flow into the hollow portion 4, or a heating current-carrying wire is drawn in the hollow portion 4 to conduct electricity. It is also possible to provide means for melting the ice and restoring the shape of the deformable member 3.

[0012]

[Effect of the device]

 As described above, according to the present invention, the deformation of the deformable member made of the shape memory polymer material changes the volume of the water flow path to compensate for the increase in the volume of water due to freezing. It is possible to obtain a water pipe that has the same retention property and strength as conventional ones and can reliably prevent the pipe from bursting due to freezing.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a water pipe according to an embodiment of the present invention, (A) showing an unfrozen state and (B) showing a frozen state.

2 is a cross-sectional view of a water pipe according to another embodiment of the present invention, (A) shows a shell and tube type heat exchanger, (B) shows a water pipe.

[Explanation of symbols]

1: Outer tube, 2: Inner tube, 3: Deformation member, 4: Cavity, 5: Refrigerant flow path, 6: Water flow path.

Claims (1)

[Scope of utility model registration request] 1. A water pipe characterized in that a deformable member formed in a tubular shape with a shape memory polymer material whose shape changes at freezing temperature is built in the pipe.