JPH0742976A - Heat transporting medium and system - Google Patents

Abstract

PURPOSE:To obtain a system which enables the obtaining a heat transporting medium easy to use with higher heat conductivity as well as relatively large heat capacity to utilize. CONSTITUTION:A microbead 1 which has a nucleus 3 comprising an inorganic matter such as lithium chlorate, larger in heat storage capacity than water and soluble in water, an internal cover layer 4 made of a hydrophobic resin such as polytetra-fluoroethylene covering the nucleus 3 and an external cover layer 5 made of a hydrophilic resin such as urea resin covering the internal cover layer 4 is mixed into water 2 to form a heat transport medium as slurry. Thus, a heat transport system is obtained using this as fluid for heat transportation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat carrier medium used in a district cooling and heating system, an in-building cooling system, etc., and a heat carrier system employing such a heat carrier medium.

[0002]

2. Description of the Related Art As a heat transfer system of this type, there are a district heating / cooling system, a building heating / cooling system, etc. There are known systems that consider effective use of waste heat from medium power lines or subway stations. Conventionally, in such a system, cold water has been used for cooling, and hot water or steam has been used for heating as the heat transfer medium.

[0003]

In a system using water as a heat transfer medium, it is impossible to keep the temperature of the medium below 0 ° C. during cooling because the water as the transfer medium freezes. . Therefore, there is a limit to the amount of heat transferred per unit volume or unit weight, and
There is a problem in that more cold water needs to flow, the pump power and the pipe diameter must be increased, and the cost also increases. On the other hand, during heating, heat can be transferred as steam even at a temperature of 100 ° C. or higher, and latent heat of steam can be used, so that the amount of transferred heat per unit volume or unit weight can be increased. However, there is a problem that when the amount of heat transferred is increased even during heating, the temperature difference from the outside becomes large and the amount of heat dissipation becomes large. Therefore, for example, a heat carrier medium in which paraffin is formed in the core and dispersed in water by covering the core with a urea resin as a surfactant to form micelles is proposed. There is a problem that its thermal conductivity is poor and it is difficult to melt in the heat exchange section.

Therefore, an object of the present invention is to obtain a heat carrier medium which has a relatively large heat capacity and a high heat conductivity and is easy to use as a heat carrier medium, and to obtain a system utilizing the heat carrier medium.

[0005]

To achieve this object, the heat transfer medium according to the present invention is characterized in that the core has a heat storage capacity larger than that of water and is made of an inorganic substance soluble in water, and covers the core. Micro beads having an inner coating layer formed of a hydrophobic resin and an outer coating layer formed of a hydrophilic resin covering the inner coating layer are mixed in water to form a slurry. In addition, in the heat transfer system, this heat transfer medium is used, and its action and effect are as follows.

[0006]

Action: In other words, the microbeads consist of a core, an inner coating layer,
It has a three-layer structure with an outer coating layer, which is dispersed in water. Then, the inner coating layer prevents the water-soluble inorganic material forming the nuclei from dissolving in water, and the outer coating layer ensures a preferable dispersed state in water. And from the height of the heat storage capacity of the inorganic material that constitutes the core, the heat transfer medium as a whole has a larger heat storage capacity than the case of water alone, and the unit for constant heat exchanger heat output. It is possible to reduce the flow rate of the carrier medium per unit time. Further, even when the microbeads are mixed in water, elution of the heat storage material that becomes the core of the inside or mixing of water into the heat storage material does not occur due to the structure of the inner coating layer. Further, since it is possible to select an inorganic substance having a relatively high thermal conductivity as the nucleus-forming inorganic substance, it is possible to obtain a heat carrier medium having preferable characteristics capable of exchanging heat in a short time.

[0007]

Therefore, by obtaining a heat carrier medium having a relatively large heat capacity and a high heat conductivity, which is easy to use as a heat carrier medium, a system can be constructed by using this heat carrier medium to obtain a constant temperature. Since the flow rate of the carrier medium per unit time related to the heat exchange output of was reduced, it became possible to reduce the pump power and the pipe diameter that should be equipped in the system, and it was possible to reduce the equipment scale and cost.

[0008]

EXAMPLES The structure of the heat carrier medium of the present application will be described below. This heat carrier medium is made by dispersing microbeads 1 having a heat storage capacity larger than that of water in water 2 to form a slurry, and the heat storage capacity as a whole is increased.
As shown in FIG. 1, the microbeads 1 have a core 3 having a heat storage capacity larger than that of water and made of lithium chlorate trihydrate (LiClO ₃ .3H ₂ O) as a water-soluble inorganic substance.
And an inner coating layer 4 formed of polytetrafluoroethylene as a hydrophobic resin that covers the core 3, and an outer coating layer 5 formed of a urea resin as a hydrophilic resin that covers the inner coating layer 4. Is configured. However, in order to facilitate understanding in FIG. 1, the size of the microbeads 1 is enlarged and drawn, and the average particle size is 1 to 10
It is about μm, and 30 wt% with respect to 2 of water is dispersed and made into a slurry. Further, the lithium chlorate forming the core 3 has its melting point in the temperature range of about 5 to 12 ° C.

An experiment for verifying the usefulness of the heat carrier medium of the present application will be described below. The structure of the heat transfer medium performance test apparatus 10 is shown in FIG. Here, the device 10 includes a heat storage tank 11, a circulation pump 12, a flowmeter 13, a heat exchanger 14, and a differential pressure gauge 15, and a main pipe 16 in which a heat carrier medium to be tested circulates, and the heat exchanger 14 Circulation pump 17 for supplying constant-temperature heat medium to heat exchange pipe 19 equipped with constant-temperature heater 18
And is configured. Main experiment 1
6 and the inlet temperature of the heat exchange pipe 19 to the heat exchanger 14 (T
in, T'in) is maintained, and the outlet temperature (Tout, Tout from the heat exchanger 14 due to the difference in heat storage capacity of the heat carrier medium,
There will be a difference in T'out). The operating conditions and measurement items during the experiment are as follows. Operating conditions Heat carrier medium flow rate 1.6m / sec Main pipe diameter set to 10 and 15mm Measurement item Heat exchanger inlet and outlet temperatures (Tin and T
out) Heat exchanger inlet and outlet temperatures on the constant temperature side (T'in and T'out) Pressure loss in main pipe (ΔP) Furthermore, from these measurement results, the amount of heat released by the heat transfer medium in the heat exchanger 14 Was calculated as the transportable heat quantity, and the required pump power (Lw) was determined by the following equation 1.

[0010]

[Equation 1]

The obtained results are shown in Table 1 together with the results of Comparative Examples 1 and 2.

[0012]

[Table 1]

Here, Comparative Example 1 refers to the case where only water is used as the heat transfer medium, and Comparative Example 2 refers to the apparatus shown in FIG. The case where only water is used is shown.

As a result, 3 microbeads 1 according to the present invention were prepared.
It was revealed that the heat transfer amount was 11.9 kW and the required pump power was 13.6 W / m by using the heat transfer medium mixed at 0 wt%. This result shows that compared with the case where only water is used as the heat transfer medium, the amount of transferred heat can be more than doubled in comparison with Comparative Example 1 in which the tube diameter of the main tube 14 is the same. Comparative example 2 with thicker
In comparison with, it is shown that a larger amount of heat can be transferred and the transfer power can be reduced.

By adopting the above-mentioned heat carrier medium, the efficiency of the district heating / cooling system, the building cooling / heating system and the like as the heat carrier system, the reduction of the equipment scale, and the cost reduction have been achieved.

[Other Embodiments] Other embodiments of the present application will be described below. (A) In the above embodiment, the mixing ratio of the micro-beads is set to 30 wt%, but this ratio can be set arbitrarily, and 10 to 30 wt% is practically preferable. (B) In the above example, the lithium chlorate trihydrate (Li
Although ClO ₃ .3H ₂ O) is adopted, it is also possible to adopt dipotassium hydrogen phosphate hexahydrate (K ₂ HPO ₄ .6H ₂ O) or the like. (C) In the above embodiment, polytetrafluoroethylene was used as the hydrophobic resin, but it is also possible to use polytrifluorovinyl acetate or the like. (D) In the above embodiment, the urea resin was adopted as the hydrophilic resin, but it is also possible to adopt polyamide or the like.

It should be noted that reference numerals are added to the claims for convenience of comparison with the drawings, but the present invention is not limited to the configurations of the accompanying drawings by the entry.

[Brief description of drawings]

FIG. 1 is a diagram showing the structure of microbeads.

FIG. 2 is a diagram showing a configuration of a heat carrier medium performance test apparatus.

[Explanation of symbols]

 1 microbead 2 water 3 nucleus 4 inner coating layer 5 outer coating layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshi Tamura, 4-1-2, Hirano-cho, Chuo-ku, Osaka City, Osaka Prefecture Osaka Gas Co., Ltd. (72) Hajime Toyonaga, 4-chome, Hirano-cho, Chuo-ku, Osaka-shi, Osaka 1-2 No. 1 in Osaka Gas Co., Ltd. (72) Inventor Takatoshi Nakahira 4-1-2 Hirano-cho, Chuo-ku, Osaka City, Osaka Prefecture Osaka Gas Co., Ltd.

Claims (4)

[Claims] 1. A core (3) having a heat storage capacity larger than that of water and made of a water-soluble inorganic substance, an inner coating layer (4) formed of a hydrophobic resin for covering the core (3), A heat carrier medium formed into a slurry by mixing microbeads (1) having an outer coating layer (5) formed of a hydrophilic resin covering the inner coating layer (4) into water (2). 2. The heat carrier medium according to claim 1, wherein the inorganic substance is lithium chlorate. 3. The heat carrier medium according to claim 1, wherein the hydrophobic resin is polytetrafluoroethylene and the hydrophilic resin is a urea resin. 4. A heat transfer system using the heat transfer medium according to claim 1, 2 or 3 as a heat transfer fluid.