JP2002048484A - Refrigerant circulating route of natural circulation type heat pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the refrigerant circulating route of a natural circulation type heat pump capable of simplifying the structure of an evaporator without lowering heat exchange efficiency as a proper velocity of flow of a refrigerant is maintained by preventing a reverse flow of refrigerant gas, evaporated in the evaporator, to the refrigerant inlet side of the evaporator. SOLUTION: The refrigerant circulating route is provided with the evaporator 3 and a condenser. Refrigerant liquid from the condenser is guided to the evaporator 3 and evaporated refrigerant steam is guided to the condenser. In the so formed refrigerant circulating rout of a natural circulation type heat pump, a trap 4 is provided to prevent a reverse flow of refrigerant steam evaporated in the evaporator 3 to the inlet side of the evaporator 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a refrigerant circulation path of a natural circulation heat pump using a natural refrigerant.

[0002]

2. Description of the Related Art FIG. 1 is a diagram showing a configuration of a refrigerant circulation path of a conventional natural circulation heat pump. This cycle system is a natural circulation cycle system in which a refrigerant liquid is stored in a surge tank 1 installed at an upper portion, and supplied to an evaporator 3 at a lower portion through the refrigerant flow control valve 2. In this natural circulation cycle system, when the substantial liquid level difference H is small, the refrigerant flow velocity V in the evaporator 3 is high, the flow velocity loss is large, the coil resistance in the evaporator 3 is large, and the friction loss is large. The discharge of the evaporated gas becomes worse, and in the worst case, the evaporated gas may flow backward from the flow control valve 2 to the surge tank 1.

In the natural circulation heat pump cycle, it is important that the refrigerant gas evaporated in the evaporator 3 can be efficiently discharged to the outlet side without stagnation in the evaporator 3. For this reason, conventionally, the flow velocity of the refrigerant in the evaporator 3 has been suppressed to reduce the pressure loss of the refrigerant, the inlet pushing pressure has been increased, the structure of the evaporator 3 has been complicated by giving a gradient to the evaporating coil, and the like. Is adopted. However,
This lowers the heat exchange efficiency of the evaporator 3 and increases the size,
As a result, there is a problem that the manufacturing cost is increased.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and is intended to prevent a refrigerant gas evaporated in an evaporator from flowing back to a refrigerant inlet side of an evaporator, thereby providing an appropriate refrigerant. An object of the present invention is to provide a refrigerant circulation path of a natural circulation heat pump that can simplify the structure of an evaporator without lowering the heat exchange efficiency while maintaining the flow rate.

[0005]

According to the first aspect of the present invention, an evaporator and a condenser are provided. The refrigerant liquid from the condenser is guided to the evaporator, and the evaporated refrigerant vapor is discharged. In a refrigerant circulation path of a natural circulation heat pump configured to lead to a condenser, a trap is provided at an inlet side of the evaporator to prevent a backflow of the refrigerant vapor evaporated by the evaporator.

According to a second aspect of the present invention, in the refrigerant circulation path of the natural circulation heat pump according to the first aspect, the refrigerant circulation path is a carbon dioxide system of a natural circulation heat pump device combining an ammonia refrigerant and a carbon dioxide refrigerant. And a trap for preventing a backflow of the refrigerant vapor evaporated by the evaporator is provided at an inlet side of the evaporator in the refrigerant circulation path.

According to a third aspect of the present invention, in the refrigerant circulation path of the natural circulation heat pump according to the second aspect, the liquefied carbon dioxide from the cascade condenser is interposed between the cascade condenser and the trap in the carbon dioxide based refrigerant circulation path. A surge drum containing a predetermined amount of carbon is provided, and a mixture of carbon dioxide and liquefied carbon dioxide discharged from an evaporator is guided to the surge drum.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a diagram showing a configuration example of a refrigerant circulation path of the natural circulation heat pump according to the present invention.
In FIG. 2, portions denoted by the same reference numerals as those in FIG. 1 indicate the same or corresponding portions. In the present refrigerant circulation path, a trap (a U-shaped trap in the figure) 4 is provided at the inlet of the evaporator 3, and the refrigerant liquid stored in the surge tank 1 is supplied to the evaporator 3 via the refrigerant flow control valve 2 and the trap 4. Liquid. In addition, evaporator 3
(Mixture of refrigerant vapor and refrigerant liquid) discharged from the tank returns to the surge tank 1, the refrigerant vapor is sent to a condenser (not shown), and the refrigerant liquid flows to the evaporator 3 again.
The refrigerant gas condensed by the condenser becomes a refrigerant liquid and is supplied to the surge tank 1 through the on-off valve 10.

As described above, the trap 4 is provided at the entrance of the evaporator 3.
The backflow of the refrigerant gas generated in the evaporator 3 is prevented by the trap 4. Therefore, only the refrigerant liquid is always supplied to the evaporator 3, and the natural circulation cycle is reliably executed. Further, the inside of the evaporator coil of the evaporator 3 does not need to have a complicated structure such as providing a gradient to the evaporator coil while maintaining an appropriate flow rate of the refrigerant, thereby enabling efficient heat exchange.

FIG. 3 is a diagram showing an example of a system configuration of a natural circulation type heat pump that combines an ammonia refrigerant and a carbon dioxide gas refrigerant using a refrigerant circulation path according to the present invention. In FIG. 3, portions denoted by the same reference numerals as those in FIGS. 1 and 2 indicate the same or corresponding portions. As shown, the carbon dioxide refrigeration system is configured by connecting a cascade condenser 13, a receiver 5, a flow control valve 2, a trap 4, and an evaporator 3 via a carbon dioxide gas refrigerant path 9. The ammonia refrigeration system includes a cascade condenser 13, a compressor 11, and a condenser 1
2, the expansion valve 14 and the flow control valve 15 are connected by an ammonia refrigerant path 16.

The carbon dioxide gas evaporated in the evaporator 3 is cooled by the cascade condenser 13 and condensed to become liquefied carbon dioxide gas.
The condensed liquefied carbon dioxide gas accumulates in the receiver 5 and passes through the flow control valve 2 due to the thermosiphon phenomenon, and the evaporator 3
Circulates to Also at this time, the trap 4 installed on the inlet side of the evaporator 3 prevents the backflow of the carbon dioxide gas from the evaporator 3, so that natural circulation is reliably performed. Further, the evaporator 3 can maximize the heat exchange efficiency while maintaining an appropriate flow rate of the carbon dioxide gas and without having a complicated structure such as giving a gradient to the evaporating coil.

In the ammonia refrigeration system, the ammonia gas which has cooled and evaporated the carbon dioxide gas in the cascade condenser 13 is compressed in the compressor 11 and condensed in the condenser 12 to become ammonia liquid. A circulating cycle which returns to the cascade capacitor 13 through the circulating capacitor 13 is constituted.

FIG. 4 is a diagram showing an example of a system configuration of a natural circulation heat pump in which an ammonia refrigerant and a carbon dioxide gas refrigerant adopting the refrigerant circulation path according to the present invention are combined. In FIG. 4, portions denoted by the same reference numerals as those in FIGS. 1, 2 and 3 indicate the same or corresponding portions. The carbon dioxide gas evaporated by the evaporator 3 is cooled by the cascade condenser 13 and condensed to become liquefied carbon dioxide gas. The condensed liquefied carbon dioxide gas accumulates in the receiver 5, passes through the on-off valve 6, and further passes through the float valve 8.
A predetermined amount is stored in the surge drum 7 via the. The liquefied carbon dioxide gas accumulated in the surge drum 7 flows through the trap 4 to the evaporator 3 due to the thermosiphon phenomenon, evaporates, gasifies, and returns to the surge drum 7 again.

In the surge drum 7, a mixture of liquid and gas circulated from the evaporator 3 is separated, and the gas circulates to the cascade condenser 13 and the liquid circulates to the evaporator 3 again. At this time, the trap 4 provided between the surge drum 7 and the evaporator 3
Prevents a backflow of gas from the evaporator 3, so that a natural circulation cycle is reliably performed. Particularly in the case of the present example, in order to increase the heat exchange efficiency from the outlet of the evaporator 3, it is very often returned with a mixture of liquid and gas. For this reason, the refrigerant pressure loss in the evaporator 3 becomes large, and the backflow of the evaporative gas easily occurs. By providing the trap 4 on the inlet side of the evaporator 3, the gas backflow prevention effect is very large.

In the above example, the trap 4 is described as a U-shaped trap. However, the trap is not limited to a U-shaped trap. For example, as shown in FIG. A configuration in which the flow control valve 2 is provided may be employed. In short, any structure that can prevent the backflow of the refrigerant vapor evaporated by the evaporator 3 may be used.

[0016]

As described above, according to the invention described in each claim, the following excellent effects can be obtained.

According to the first aspect of the present invention, since the trap for preventing the backflow of the refrigerant vapor evaporated by the evaporator is provided at the inlet side of the evaporator, the backflow of the refrigerant gas generated in the evaporator is trapped. And the refrigerant is always supplied only to the evaporator, and the natural circulation cycle is reliably executed. Also,
The refrigerant flowing in the evaporator coil of the evaporator maintains an appropriate flow rate, and does not need to have a complicated structure such as giving a gradient to the evaporator coil, so that efficient heat exchange can be performed.

According to the second aspect of the present invention, the refrigerant evaporated by the evaporator is provided at the inlet side of the evaporator in the carbon dioxide-based refrigerant circulation path of the natural circulation heat pump device combining the ammonia refrigerant and the carbon dioxide refrigerant. Since a trap to prevent the backflow of steam is provided, a trap installed at the inlet side of the evaporator prevents the backflow of carbon dioxide gas generated in the evaporator.
Natural circulation is ensured. Also, the carbon dioxide gas flowing in the evaporator coil of the evaporator maintains an appropriate flow rate and does not have a complicated structure such as providing a gradient to the evaporator coil, so that the heat exchange efficiency is maximized. be able to.

According to the third aspect of the present invention, a surge drum for containing a predetermined amount of liquefied carbon dioxide from the cascade condenser is provided between the cascade condenser and the trap, and the surge drum is provided with carbon dioxide gas from the evaporator. The arrangement for directing a mixture of liquefied carbon dioxide ensures that a natural circulation cycle takes place, since the trap prevents backflow of gas from the evaporator. Particularly in this case, the refrigerant coming out of the evaporator is very often a mixture of liquid and gas in order to increase the heat exchange efficiency, so that the refrigerant pressure loss in the evaporator becomes large and the backflow of the evaporative gas easily occurs, and a trap is provided Thus, the effect of preventing the backflow of the evaporated carbon dioxide gas is very large.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration example of a refrigerant circulation path of a conventional natural circulation heat pump.

FIG. 2 is a diagram showing a configuration example of a refrigerant circulation path of a natural circulation heat pump according to the present invention.

FIG. 3 is a diagram showing an example of a system configuration of a natural circulation heat pump that combines an ammonia refrigerant and a carbon dioxide gas refrigerant that employs a refrigerant circulation path according to the present invention.

FIG. 4 is a diagram illustrating an example of a system configuration of a natural circulation heat pump that combines an ammonia refrigerant and a carbon dioxide gas refrigerant that employs a refrigerant circulation path according to the present invention.

FIG. 5 is a diagram showing a configuration example of a refrigerant circulation path of the natural circulation heat pump according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Surge tank 2 Refrigerant flow control valve 3 Evaporator 4 Trap 5 Receiver 6 On-off valve 7 Surge drum 8 Float valve 9 Carbon dioxide refrigerant passage 10 On-off valve 11 Compressor 12 Capacitor 13 Cascade condenser 14 Expansion valve 15 Flow control valve 16 Ammonia refrigerant Route

Claims (3)

[Claims] 1. A refrigerant circulation path of a natural circulation heat pump comprising an evaporator and a condenser, wherein the refrigerant liquid from the condenser is guided to the evaporator, and the evaporated refrigerant vapor is guided to the condenser. A refrigerant circulation path for a natural circulation heat pump, wherein a trap for preventing backflow of refrigerant vapor evaporated by the evaporator is provided at an inlet side of the evaporator. 2. The refrigerant circulation path of the natural circulation heat pump according to claim 1, wherein the refrigerant circulation path is a carbon dioxide refrigerant circulation path of a natural circulation heat pump device combining an ammonia refrigerant and a carbon dioxide refrigerant. A refrigerant circulation path for a natural circulation heat pump, wherein a trap for preventing a backflow of the refrigerant vapor evaporated by the evaporator is provided at an inlet side of the evaporator in the refrigerant circulation path. 3. The refrigerant circulation path of the natural circulation heat pump according to claim 2, wherein a predetermined amount of liquefied carbon dioxide from the cascade condenser is stored between the cascade condenser and the trap in the carbon dioxide refrigerant circulation path. A surge drum
A refrigerant circulation path of a natural circulation heat pump, wherein a mixture of carbon dioxide and liquefied carbon dioxide discharged from the evaporator is guided to the surge drum.