JP2627990B2 - Heat transport system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat transfer system for a cooling and heating apparatus, and more particularly, to a heat transfer system using an aqueous solution containing a thermoreversible water-absorbing polymer as a heat transfer medium and capable of reducing the amount of circulation. Regarding transportation systems.

[0002]

2. Description of the Related Art Conventional absorption refrigerators perform cooling and heating by generating cold and hot water mainly using water as a refrigerant and lithium bromide as an absorbent, and circulating them to an indoor air conditioner by means of heat transport using a cold and hot water pump. . That is, as shown in FIG. 2, the absorption refrigerator S includes a cooling cooler D and a cooling and heating heat source 1, generates cold and hot water, and sends a cold and hot water pump P to the indoor air conditioner R.
It is circulated using. And cold and hot water as a heat transport medium was mainly water.

As an alternative to water as a heat transport medium, the present applicant has proposed CFCs disclosed in JP-A-1-247968 and JP-A-2-52062.

[0004]

When water is used as a heat transport medium of a heat transport circuit (cooling / hot water circuit) of an absorption refrigerator or an absorption heat pipe, the circulation amount of the solution is large and the discharge pressure of the circulation pump is low. As a result, the running cost is increased due to the electricity consumption of the cold / hot water pump. Also, since the transfer of heat of cold and hot water changes only by sensible heat, the piping of the heat transport circuit (cooling and hot water circuit) becomes thicker,
There was also a disadvantage that the initial cost of the construction was high. On the other hand, during cooling, the temperature of cold water guided to the indoor air conditioner is generally as low as about 7 ° C., but the temperature of refrigerant evaporation in the evaporator of the absorption refrigerator at this time is about 5 ° C. It is desirable that the absorption refrigerator be operated in a state where the temperature of the chilled water is high in view of the refrigeration operation characteristics. However, operating at such a low temperature has a disadvantage that the coefficient of performance is reduced and the running cost is increased.

When chlorofluorocarbon is used as a heat transport medium in a heat transport circuit (cooled / hot water circuit), the chlorofluorocarbon medium is circulated with a liquid or vapor at a set temperature. A pump and a compressor are required, and the medium temperature during heating is higher than during cooling, so a higher-pressure compressor is required. Since the rate of change in volume is large due to the phase change of the gas phase and the liquid phase, expansion means is required. As a result, there is a disadvantage that the cost is increased. Further, when the heat siphon system is employed for heating, the positions of the indoor air conditioner and the absorption refrigerator are limited by the flow of the medium (the indoor air conditioner must be installed above the absorption refrigerator). Moreover, CFCs have environmental problems such as destruction of the ozone layer.

Accordingly, an object of the present invention is to solve these problems and to circulate an aqueous solution containing a thermoreversible water-absorbing polymer as a heat transport medium of a heat transport circuit (cold / hot water circuit), thereby circulating the aqueous solution. It is an object of the present invention to provide a heat transport system capable of reducing the load on a circulation pump and reducing the required power of an absorption refrigerator main body.

[0007]

SUMMARY OF THE INVENTION The object of the present invention is as follows.
This is achieved by the heat transport system having the following configuration. That is, in the heat transport circuit, a thermoreversible water-absorbing polymer A having a transition temperature near the cold water temperature during cooling, and a thermoreversible water-absorbing polymer B having a transition temperature near the warm water temperature during heating. And a heat transport circuit is provided between the evaporator of the absorption refrigerator and the indoor air conditioner for cooling and heating.

[0008]

According to the present invention, heat is transported by circulating an aqueous solution containing a thermoreversible water-absorbing polymer as a heat transport medium of a heat transport circuit (cooling / heating water circuit). The thermoreversible water-absorbing polymer separates from water at a transition temperature or higher, and adsorbs and dissolves water at a temperature lower than the transition temperature. At this time, an endothermic reaction occurs when the water is separated from water, and an exothermic reaction occurs when the water is absorbed (adsorbed). In the heat transport circuit (cooling / heating water circuit), a thermoreversible water-absorbing polymer A having a transition temperature near the cooling water temperature during cooling and a thermoreversible water-absorbing polymer having a transition temperature near the warm water temperature during heating. The aqueous solution containing molecule B is circulated. Then, during cooling, the thermoreversible water-absorbent polymer A is cooled by the evaporator of the absorption refrigerator, dissolved in the aqueous solution, and transported to the indoor air conditioner. At this time, since the thermoreversible water-absorbing polymer B has a transition temperature or lower, it is naturally dissolved in the aqueous solution. The aqueous solution transported to the indoor air conditioner draws heat from the room and becomes higher than the transition temperature of the thermoreversible water-absorbing polymer A, and the thermoreversible water-absorbing polymer A separates from water and absorbs heat. It is suspended and circulated to the evaporator. At this time, since the transition temperature of the thermoreversible water-absorbing polymer B is on the higher temperature side, the thermoreversible water-absorbing polymer B is circulating as an aqueous solution in the heat transport circuit (cooling / heating water circuit). Next, at the time of heating, the temperature of the aqueous solution in the heat transport circuit (cold / hot water circuit) is high, and the thermoreversible water-absorbing polymer A is at or above its transition temperature. In a suspended state. However, since the transition temperature of the thermoreversible water-absorbing polymer B is in the vicinity of this high temperature state, it is heated by the evaporator of the absorption refrigerator and separated from water to be in a suspended state and enters the indoor air conditioner. Here, an aqueous solution that releases heat in the room and becomes lower than the transition temperature,
The thermoreversible water-absorbing polymer B generates heat while melting to heat the room. As described above, in the present invention, heat absorption and heat generation (latent heat) at the time of phase transition of the thermoreversible water-absorbing polymer are used, so that more efficient heat transport is possible.

[0009]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram in the case of carrying out the present invention, wherein reference symbol S denotes an absorption refrigerator, R denotes an indoor air conditioner, and C denotes a heat transport circuit (cooling / hot water circuit). The heat transport circuit (cooling / heating water circuit) C connects the absorption refrigerator S and the indoor air conditioner R.

In the absorption refrigerator S, an absorption liquid using lithium bromide as an absorbent and water as a refrigerant is circulated. A high-temperature regenerator 1 for heating the dilute solution, and a refrigerant from the heated dilute solution, A separator 2 for separating the vapor and the intermediate-concentration absorbent, and a low-temperature regenerator 3 for heating the intermediate-concentration absorbent cooled by the high-temperature heat exchanger 7 with the refrigerant vapor to generate refrigerant vapor again.
A condenser 4 for condensing the refrigerant vapor generated in the low-temperature regenerator 3 and the refrigerant vapor used for heating the low-temperature regenerator 3, an evaporator 6 for evaporating the refrigerant liquid condensed in the condenser 4,
A low-temperature heat exchanger 8 for exchanging heat with the dilute solution to cool the absorbing liquid generated by evaporating the refrigerant in the low-temperature regenerator 3 and an evaporator 6 for evaporating the absorbing liquid cooled in the heat exchanger. An absorber 5 for absorbing a refrigerant vapor to generate a dilute solution, and the generated dilute solution is passed through heat exchangers 7 and 8 to a high-temperature regenerator 1.
And a pipe connecting the side of the evaporator 6 where the heat transport medium is not flowing and the separator 2 via a cooling / heating switching valve 10. The line connected from the separator 2 to the evaporator 6 by a pipe via a cooling / heating switching valve 10 has the cooling / heating switching valve 10 closed during cooling and opened during heating. Then, the condenser 4 and the absorber 5 are cooled by the cooling means 11 and 12. This cooling means may be either air-cooled or water-cooled.

A heat transport circuit (cooling / heating water circuit) C is connected to the evaporator 6 of the absorption chiller S, and the other is connected to an indoor heat exchanger 13 in the indoor air conditioner R. Heat exchange. An aqueous solution containing a thermoreversible water-absorbing polymer as a heat transport medium is circulated in a heat transport circuit (cooled / hot water circuit) C by a circulation pump 14. The aqueous solution containing the thermoreversible water-absorbing polymer as a heat transport medium includes a thermoreversible water-absorbing polymer A having a transition temperature near a cold water temperature during cooling, and a transition temperature near a warm water temperature during heating. And a thermoreversible water-absorbing polymer B having the following formula:

These thermoreversible water-absorbing polymers can be synthesized from various polymer substances, and the following ones are used. N-isopropylacrylamide or Nn
N-substituted acrylamide derivatives such as -propylacrylamide, N-substituted acrylamide such as Nn-propylmethacrylamide
-Substituted methacrylamide derivatives, N, N-disubstituted acrylamide derivatives, polyether substances such as polyvinyl methyl ether, and vinyl alcohol substances.

The concentration of the thermoreversible water-absorbing polymer in the aqueous solution is preferably 10 to 35% by weight. If it is 10% by weight or less, the total heat of transition becomes too small to be used, and if it is 35% by weight or more, the viscosity of the aqueous solution becomes too high. When it is 10 to 35% by weight,
The viscosity of the aqueous solution falls within a range of about 30 times or less of water.
An example is described below.

(Example) As a thermoreversible water-absorbing polymer A, poly-N-acryloyl-1,4- having a transition temperature of 9.5 ° C.
Dioxa-8-azaspiro [4,5] decane was used, and poly-N-ethoxyethyl methacrylamide having a transition temperature of 45.5 ° C. was used as the thermoreversible water-absorbing polymer B. A polymer aqueous solution containing each of these in an amount of 20% by weight is circulated through a heat transport circuit (cooled / hot water circuit) C as a heat transport medium. Switching between cooling and heating is performed by the absorption refrigerator S in FIG. 1, and the heat transport medium always flows through the evaporator 6 of the absorption refrigerator S.

At the time of cooling, the cooling / heating switching valve 10 is closed, and the cooling system operates in the absorption refrigerator S.
At this time, the refrigerant evaporates in the evaporator 6 to have a temperature of about 5 ° C. As a result, since both the thermoreversible water-absorbing polymers A and B contained in the heat transport medium have a transition temperature or lower, they are dissolved in water to be in an aqueous solution state. This heat transport medium is sent from the evaporator 6 to the indoor air conditioner R by the circulation pump 14, and the indoor heat exchanger 13 deprives the indoor heat of the room, and the temperature rises. Since A becomes higher than the transition temperature, it absorbs heat while removing water to take away heat from the surroundings. In this case, the thermoreversible water-absorbing polymer A is in a suspended state, returns to the evaporator 6 again, is cooled, is dissolved in water, and becomes an aqueous solution. Since the thermoreversible water-absorbing polymer B has a transition temperature or lower throughout this cycle, it remains an aqueous solution.

At the time of heating, the cooling / heating switching valve 10 is opened, the heated refrigerant vapor is introduced from the separator 2 into the evaporator 6, and the temperature is raised to about 60 ° C. Therefore, the heat transport medium is heated, and since both the thermoreversible water-absorbing polymers A and B have a transition temperature or higher, they are separated from water to be suspended and transported from the evaporator 6 to the indoor air conditioner R. . The heat transport medium that has entered the indoor air conditioner R in this suspended state releases heat into the room in the indoor heat exchanger 13 and lowers its temperature. As a result, when the temperature becomes 45.5 ° C. or lower, the thermoreversible water-absorbing polymer B becomes lower than the transition temperature, so that it generates heat while dissolving in water and radiates heat to the surroundings. The thermoreversible water-absorbing polymer B thus converted to an aqueous solution is again supplied to the evaporator 6.
Then, it is heated and separated from the water to be suspended. Since the thermoreversible water-absorbing polymer A has a transition temperature or higher throughout this cycle, it remains in a suspended state.

As described above, in the present invention, since heat absorption and heat generation at the time of phase transition of the thermoreversible water-absorbing polymer are utilized at the time of cooling or heating, efficient heat transport is possible. In addition, as the thermoreversible water-absorbing polymer A, in addition to those used in the above examples, poly-N-1- having a transition temperature of 11.0 ° C.
Methoxymethylpropyl acrylamide and transition temperature 8.
Poly-N-isopropoxypropyl acrylamide at 7 ° C. is a thermo-reversible water-absorbing polymer B, and poly-N- (2,2-dimethoxyethyl) having a transition temperature of 60.5 ° C.
It has been confirmed that -N-methylacrylamide and poly-N- (1,3-dioxolan-2-yl) -N-methylacrylamide having a transition temperature of 55.5 ° C. can be used.

[0018]

As described above, according to the present invention, the heat reversible water-absorbing polymer is subjected to heat transport utilizing the heat of transition (latent heat) at the time of separation from water or at the time of dissolution in water. I have. So, let's examine the effect in comparison with water. The circulation rate of the heat transport medium is 600 kg / h, the temperature change is 5 ° C., and an aqueous solution containing 20% by weight of the thermoreversible water-absorbing polymer is used.
At this time, the transition heat of the thermoreversible water-absorbing polymer is about 20 kcal.
/ kg. First, in the case of water, 600 kg / h × 5 ° C. × 1
Heat transfer is possible at (specific heat) × 1 (specific gravity) = 3000 kcal / h. In contrast, when the thermoreversible water-absorbing polymer is used, the balance of the transition heat (latent heat) of the thermoreversible water-absorbing polymer of 20% by weight is 600 kg / h × 1 (specific gravity) × 0.2 ( Ratio in aqueous solution) × 20 kcal / kg = 2400 kcal / h, and 2400 kcal due to the phase transition of the thermoreversible water-absorbing polymer.
There is an exchange of heat of al / h. Next, the balance due to the sensible heat change is
600kg / h × 0.8 (water ratio in aqueous solution) × 5 ℃ × 1
(Specific heat) x 1 (specific gravity) = 2400 kcal / h and 600
kg / h x 0.2 (proportion in aqueous solution) x 5 ° C x 0.3 (specific heat)
X 1 (specific gravity) = 180 kcal / h, for a total of 2580 kcal
/ h. Therefore, when the thermoreversible water-absorbing polymer is used, a total of 4980 kcal / h of heat can be transported by combining the balance of the heat of transition (latent heat) and the balance by the change in sensible heat. If this is compared with the case of water, heat transport about 1.6 times is possible. That is, by using the thermoreversible water-absorbing polymer as the heat transport medium, it is possible to reduce the amount of circulation of the heat transport medium, to reduce the size of the heat exchanger of the absorption refrigerator S, and to reduce the size and weight of the indoor air conditioner R. Becomes

When a fluorocarbon-based material is used, the rate of change in volume is large due to the phase change between the gas phase and the liquid phase, and not only a compressor but also an expansion means is required. In the case of using a polymer, even a phase change that obtains the same latent heat is a change from an aqueous solution to a suspended state (between a solid phase and a liquid phase). Only the circulation pump improved.

[Brief description of the drawings]

FIG. 1 is a schematic view of an embodiment for implementing the present invention.

FIG. 2 is a diagram for explaining a conventional technique.

[Explanation of symbols]

 S Absorption refrigerator R Indoor air conditioner C Heat transport circuit 6 Evaporator 13 Indoor heat exchanger 14 Circulation pump

Claims (2)

(57) [Claims] 1. A thermoreversible water-absorbing polymer A having a transition temperature near a cold water temperature during cooling, and a thermoreversible water-absorbing polymer having a transition temperature near a hot water temperature during heating in a heat transport circuit. A heat transport system comprising circulating an aqueous solution containing a molecule B. 2. The heat transport system according to claim 1, wherein the heat transport circuit is provided between the evaporator of the absorption refrigerator and an indoor air conditioner for cooling and heating.