JP3225142B2 - Heat transport device - 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 transport apparatus for transporting heat by circulating a heat transport medium by operating a pump.

[0002]

2. Description of the Related Art There is a heat transport device in which a heat transport medium, for example, a refrigerant, which has passed through a condenser on a heat source side is stored in a tank, and the refrigerant in the tank is passed through an evaporator on a use side and returned to the condenser by operating a pump. . An example is shown in FIG.

In FIG. 1, reference numeral 1 denotes an absorption refrigerator serving as a heat source, and a refrigerant is cooled by a condenser 2. This condenser 2
The tank 4 is connected to the tank 4 via the pipe 3, and the suction port of the pump 6 is connected to the tank 4 via the pipe 5.

A check valve (also referred to as a check valve) 8 is connected to a discharge port of the pump 6 via a pipe 7, and the check valve 8 is connected to the air conditioner 1 on a use side via a pipe 9.
0 evaporator 11 is connected. Then, the evaporator 11 and the condenser 2 are connected via the pipe 12.

A line 9 between the check valve 8 and the evaporator 11
A temperature sensor 21 is attached to the controller 22, and a detection output of the temperature sensor 21 is sent to the controller 22. Controller 2 for absorption refrigerator 1, pump 6, and air conditioner 10
3 are connected.

[0006] The controller 23 responds to the operation command from the absorption refrigerator 1 and the operation command from the air conditioner 10,
The pump 6 is driven.

The controller 22 turns on the operation of the air conditioner 10 only when the temperature detected by the temperature sensor 21 is lower than a predetermined value.

The operation will be described.

When the operation of the absorption refrigerator 1 starts, the refrigerant is liquefied in the condenser 2 and stored in the tank 4. The refrigerant in the tank 4 is sent to the evaporator 11 by the operation of the pump 6, where the refrigerant takes heat from room air and evaporates. The refrigerant that has passed through the evaporator 11 is returned to the condenser 2.

[0010]

At the start of operation, the pump 6
The refrigerant in the tank 4 is sent to the evaporator 11 at the same time as the start-up, and the refrigerant temperature at that time is equivalent to the ambient temperature in the vicinity of the tank 4. For this reason, a cooling effect is not easily obtained in the evaporator 11, that is, the air conditioner 10 cannot obtain a cooling ability, and a fresh warm air is sent into the room. In addition, the pump 6 is in useless operation until the cooling capacity is obtained, and the power cost is wasted.

In addition, during the period until the cooling capacity is obtained, since there is no heat exchange effect of the refrigerant in the evaporator 11, the gas flows from the evaporator 11 to the pipe 12 differently from the original gas phase or gas-liquid two phase. The liquid refrigerant flows, and the refrigerant becomes short in the entire cycle. In this case, appropriate heat transport becomes difficult, and it takes a long time until the cooling capacity is obtained.

As a countermeasure against this, it is necessary to adopt a large tank 4 and increase the amount of refrigerant to be charged, but this will increase the cost.

On the other hand, when the operation is started, the refrigerant in the pipeline is still in the saturated state of the ambient temperature, so that when the pump 6 is started, NPSH (suction head) becomes insufficient and cavitation may occur .

In particular, it is difficult to completely prevent cavitation because a heat transport medium such as a CFC-based refrigerant that changes in gas-liquid phase slightly changes its gas-liquid phase under the influence of temperature and pressure. It is. Moreover, there is no effective means for reliably determining the occurrence of cavitation.

When cavitation actually occurs, it is necessary to suspend the operation until bubbles existing in the pump 6 are naturally removed, and it takes a long time to resume the operation.

The present invention has been made in view of the above circumstances, and the heat transport device of the first invention can quickly obtain sufficient capacity on the evaporator side at the start of operation, and furthermore, the wasteful use of the pump. It is an object of the present invention to minimize operation costs by preventing operation as much as possible, and to perform appropriate heat transport without increasing the size of the tank.

According to the heat transport device of the second invention, the life of the pump and the pipeline can be improved by reliably detecting the cavitation .
And reduce cavitation easily and early
The purpose is to be able to.

[0018]

According to a first aspect of the present invention, there is provided a heat transport apparatus in which a heat transport medium having passed through a condenser on a heat source side is accommodated in a tank, and the heat transport medium in the tank is operated on a use side by operating a pump. In a device that returns to the condenser through the evaporator, a bypass connected in parallel to the evaporator, a valve provided in the bypass, a temperature sensor for detecting the temperature of the condenser, and a detection temperature of the temperature sensor means but to open and means for inhibiting operation of the pump is higher than the set value T _2, the valve activation to and bypass the detected temperature of the temperature sensor at the start of operation falls below the set value T ₂ of the pump at a rotation speed N ₁ After the pump is started, the temperature detected by the temperature sensor is set to a set value T ₁ (<T
And means for closing the valve and and bypass operation in ₂₎ below drops when the pump speed N ₂ (> N _1), the lowest
The pump is located at a position slightly higher than the pump
The condenser is located below the condenser and higher than the pump
Tank at the highest position and the evaporator at the highest position.
It is characterized by being placed.

In the heat transport apparatus of the second invention, the heat transport medium that has passed through the condenser on the heat source side is accommodated in a tank, and the heat transport medium in the tank is condensed by operating the pump through the evaporator on the use side. A bypass connected in parallel to the pump, a valve provided in the bypass, a means for detecting a difference between the suction side pressure and the discharge side pressure of the pump, and the difference being equal to or less than a set value. If becomes a means for opening a valve to stop the operation of the predetermined time by the pump and the bypass, the outermost
The pump is located at a lower position, but slightly higher than the pump.
The condenser is placed in a position that is not
The tank is located at a higher position and evaporates to the highest position
The container is arranged.

[0020]

[Action] In the heat transport device of the first invention, when the temperature of the condenser is higher than the set value T _2, prohibits the operation of the pump. At the start of operation, when the temperature of the condenser falls below the set value T _2,
Start the pump at a rotation speed N _1, and open the bypass valve, it is circulated and the heat transport medium in the tank from the pump to the bypass and the condenser. After the pump is started, when the temperature of the condenser falls below the set value T ₁ (<T ₂ ), the pump is operated at the rotation speed N ₂ (> N ₁ ), the bypass valve is closed, and the pressure in the tank is reduced. The heat transport medium is circulated from the pump to the evaporator and the condenser.

In the heat transport apparatus according to the second aspect of the present invention, the difference between the suction side pressure and the discharge side pressure of the pump is detected, and when the difference becomes equal to or less than a set value, the operation of the pump is stopped for a predetermined time and the bypass valve is turned off. open.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to the drawings. In the drawings, the same parts as those in FIG. 5 are denoted by the same reference numerals, and detailed description thereof will be omitted.

As shown in FIG. 1, one end of a bypass 31 is connected to a pipe 9 between the check valve 8 and the evaporator 11,
The other end of the bypass 31 is connected to the pipe 12 between the evaporator 11 and the condenser 2. That is, for the evaporator 11,
Bypasses 31 are connected in parallel. The connection position of the bypass 31 with respect to the pipe 9 and the pipe 12 is closer to the check valve 8 side and the condenser 2 side, respectively.

The bypass 31 is provided with a two-way valve 32.

A temperature sensor 33 for detecting the temperature of the condenser 2 is provided in the absorption refrigerator 1. Specifically, the temperature sensor 33 detects the temperature of a heat source (for example, water) supplied to the condenser 2.

The absorption refrigerator 1, the pump 6, the two-way valve 32,
The controller 40 is connected to the temperature sensor 33.

The controller 40 has functional means for controlling the operation of the pump 6 and the opening and closing of the two-way valve 32 in accordance with the operation / stop command from the absorption refrigerator 1 and the temperature T detected by the temperature sensor 33, respectively.

Next, the operation will be described with reference to the flowchart of FIG.

When the operation of the absorption refrigerator 1 starts, the refrigerant is liquefied in the condenser 2 and stored in the tank 4.

At the start of the operation, the detected temperature T of the temperature sensor 33 is compared with the set value T _2, and the detected temperature T is set to the set value T.
_If it is higher than ₂ , the operation of the pump 6 is prohibited and the pump 6 is not started yet.

Thereafter, when the detected temperature T falls below the set value T ₂ , the pump 6 is started at the rotation speed N ₁ and the two-way valve 32 is opened. The rotation speed N ₁ corresponds to the minimum pump pressure required to circulate the refrigerant in the tank 4 from the pump 6 through the bypass 31 to the condenser 2.

In this manner, the refrigerant in the tank 4 is circulated from the pump 6 to the condenser 2 through the bypass 31 and is not passed through the evaporator 11, so that the temperature of the refrigerant can be quickly and efficiently reduced.

After the pump 6 is started, the detected temperature T becomes equal to the set value T.
_When it falls below ₁ (<T ₂ ), the pump 6 is steadily operated at the rotation speed N ₂ (> N ₁ ), and the two-way valve 32 is closed. The rotation speed N ₂ is controlled by the pump 6
To the condenser 2 through the evaporator 11 to the condenser 2.

In this way, by circulating the low-temperature refrigerant in the tank 4 from the pump 6 to the evaporator 11 and the condenser 2, a cooling action can be immediately obtained in the evaporator 11. Therefore, sufficient cooling capacity is exhibited in the air conditioner 10, and cool air is blown into the room. The warm unpleasant wind is not blown out.

Referring to the operation of the pump 6, the operation is initially for cooling the refrigerant in the tank 4 which is equal to the ambient temperature in the vicinity of the tank. 2 for transporting the refrigerant cooled in 2. In other words, useless operation of the pump 6 as in the related art is prevented as much as possible, thereby reducing the power cost.

Moreover, the refrigerant sent to the evaporator 11 is sufficiently vaporized and flows into the pipe 12, so that the liquid refrigerant does not flow into the pipe 12 as in the prior art, so that the amount of refrigerant in the cycle is insufficient. Appropriate heat transport is possible without being awkward. In other words, it is not necessary to increase the tank 4 and increase the amount of the charged refrigerant, thereby avoiding an increase in cost.

When the detected temperature T falls below the set value T ₁ , this fact is stored by setting the flag f to “1”.

If the detected temperature T exceeds the set value T ₂ due to a decrease in the condensation capacity during operation, the operation of the pump 6 is stopped.
At the same time, the flag f is cleared to "0". When the operation of the absorption refrigerator 1 is stopped, the operation of the pump 6 is stopped. At the same time, the flag f is cleared to "0".

Clearing the flag f to "0" is for repeating the above-described operation start control when the pump 6 is restarted.

Next, a second embodiment of the present invention will be described.

Here, as shown in FIG. 3, a bypass 34 is connected in parallel to the pump 6 and the check valve 8. The bypass 34 is provided with a two-way valve 35.

A pressure sensor 36 is attached to the pipe 5 connected to the suction port of the pump 6. A pressure sensor 37 is attached to the pipe 7 connected to the discharge port of the pump 6. The detection outputs of these pressure sensors 36 and 37 are sent to a differential pressure switch 38.

The differential pressure switch 38 is for detecting the difference between the pressure detected by the pressure sensor 36 (pressure on the suction side of the pump 6) and the pressure detected by the pressure sensor 37 (pressure on the discharge side of the pump 6). Activated when the difference is less than a predetermined value. The output of the differential pressure switch 38 is sent to the controller 40.

The controller 40 has, in addition to the function means described in the first embodiment, a function means for stopping the operation of the pump 6 for a predetermined time and opening the two-way valve 35 when the differential pressure switch 38 is operated.

FIG. 3 shows the differential pressure switch 38 and the
The layout of the part except the controller 40 is an elevation view.
Is shown. That is, the pump 6 is located at the lowest position.
The condenser 2 is located at a position slightly higher than the pump 6.
Located at a position lower than the condenser 2 and higher than the pump 6
The tank 4 is arranged at the highest position, and the evaporator 11 is arranged at the highest position.
Is placed. The two-way valve 35 is slightly
It is arranged at a high position (a position lower than the condenser 2).
Other configurations are the same as those of the first embodiment.

Next, the operation will be described with reference to the flowchart of FIG.

The control at the start of operation is the same as in the first embodiment.

During operation, if cavitation occurs in the pump 6 for some reason, a pressure difference between the suction side and the discharge side of the pump 6 becomes smaller than a predetermined value, and the differential pressure switch 38 is operated. This operation is the detection of cavitation. According to this figure, the detection of the differential pressure switch 38, i.e. the detection of cavitation, the rotation speed of the pump 6 is performed only when the N _2, during operation of the pump 6 may be detected at all times.

When the differential pressure switch 38 is operated, the pump 6
Is forcibly stopped, and the two-way valve 35 is opened. At the same time, time count _{t 1} is started. pump
6 is forcibly stopped,
The operation in the state where the pump has occurred is prevented, and the pump 6 and
And the service life of pipes can be improved.

The operation of the pump 6 stops, and the two-way valve 3
When the valve 5 is opened, the liquid refrigerant existing in the pipe 9 after the check valve 8 drops to the pipe 5 through the bypass 34. The dropped liquid refrigerant accumulates in the pipe line 5 and the tank 4, and the tank 4 is filled with the liquid refrigerant, and the liquid refrigerant that cannot be accommodated in the tank 4 stays in the condenser 2.

As described above, the liquid refrigerant is supplied to the suction side of the pump 6.
By increasing the liquid level in the suction side supplied, NP
SH can be sufficiently secured, and cavitation can be suppressed easily and early. That is, short
The operation of the pump 6 can be restarted in time.

[0052]

When the time count t ₁ reaches the set value ta, the two-way valve 35 is closed, the two-way valve 32 is opened, and the pump 6 is started at the rotation speed N ₁ . At the same time, time count t ₂ is started. Here, the opening of the two-way valve 32 (the conduction of the bypass 31) and the activation of the pump 6 are for cooling the refrigerant in the tank 4.

When the time count t ₂ reaches the set value tb, the two-way valve 32 is closed, and the pump 6 is operated at the rotation speed N ₂ . The closing of the two-way valve 32 (the shutoff of the bypass 31) and the steady operation of the pump 6 here are for transporting the refrigerant cooled by the condenser 2 to the evaporator 11.

The present invention is not limited to the above embodiments, but can be variously modified within the scope of the invention.

[0056]

As described above, according to the present invention, the heat transport device of the first invention accommodates the heat transport medium that has passed through the condenser on the heat source side in a tank, and transfers the heat transport medium in the tank. When the pump is operated and returned to the condenser through the evaporator on the use side, a bypass connected in parallel to the evaporator, a valve provided in the bypass, and a temperature sensor for detecting the temperature of the condenser are provided. activates a means for inhibiting the operation of the pump when the detected temperature of the temperature sensor is higher than the set value T _2, the temperature detected by the temperature sensor at the start of operation falls below the set value T ₂ of the pump at a rotation speed N ₁ Means for opening the bypass valve, and, when the temperature detected by the temperature sensor drops below the set value T ₁ (<T ₂ ) after the pump is started, the pump is rotated at the rotation speed N.
Means operating at ₂ (> N ₁ ) and closing the bypass valve , the pump being located at the lowest position,
The condenser is located at a slightly higher position than the condenser
The tank is located lower and higher than the pump, the highest
Since the evaporator is arranged at the position, it is possible to quickly obtain sufficient capacity on the evaporator side at the start of operation,
In addition, unnecessary operation of the pump can be prevented as much as possible to reduce power cost, and proper heat transport can be performed without increasing the size of the tank.

In the heat transport apparatus of the second invention, the heat transport medium that has passed through the condenser on the heat source side is accommodated in a tank, and the heat transport medium in the tank is condensed by operating the pump through the evaporator on the use side. A bypass connected in parallel to the pump, a valve provided in the bypass, a means for detecting a difference between the suction side pressure and the discharge side pressure of the pump, and the difference being equal to or less than a set value. If becomes a means for opening a valve to stop the operation of the predetermined time by the pump and the bypass, the outermost
The pump is located at a lower position, but slightly higher than the pump.
The condenser is placed in a position that is not
The tank is located at a higher position and evaporates to the highest position
Since the vessel is arranged , cavitation can be reliably detected, the life of the pump and the pipeline can be improved, and cavitation can be suppressed easily and early.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a first embodiment of the present invention.

FIG. 2 is a flowchart for explaining the operation of the first embodiment.

FIG. 3 is a configuration diagram of a second embodiment of the present invention.

FIG. 4 is a flowchart for explaining the operation of the second embodiment.

FIG. 5 is a configuration diagram of a conventional device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Absorption refrigerator, 2 ... Condenser, 4 ... Tank, 6 ... Pump, 10 ... Air conditioner, 11 ... Evaporator, 31, 34 ... Bypass, 32, 35 ... Two-way valve, 33 ... Temperature sensor, 3
6, 37: pressure sensor, 38: differential pressure switch, 40: controller.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masayoshi Nakao 1-34 Roppongi, Minato-ku, Tokyo Inside NTT Facilities Co., Ltd. (72) Inventor Wataru Osawa 1-4-4 Roppongi, Minato-ku, Tokyo No. 33 NTT Facilities, Inc. (72) Inventor Tsuneo Uekusa 1-4-3 Roppongi, Minato-ku, Tokyo Inside 33 NTT Corporation, Inc. (72) Inventor Isamu Sudo Roppongi, Minato-ku, Tokyo No. 1-4-33 NTT Facilities Inc. (58) Field surveyed (Int. Cl. ⁷ , DB name) F24F 5/00 F25B 1/00 399 F25B 15/00 F28D 21/00

Claims (2)

(57) [Claims] 1. A heat transport device in which a heat transport medium having passed through a condenser on a heat source side is accommodated in a tank, and the heat transport medium in the tank is returned to the condenser through an evaporator on a use side by operating a pump. a bypass connected in parallel with the evaporator, a valve provided in the bypass, a temperature sensor for detecting the temperature of the condenser, when the temperature detected by the temperature sensor is higher than the set value T _2,
And means for inhibiting operation of said pump, at the start of operation, when the detected temperature of said temperature sensor falls below the set value T _2, the means for opening the start the pump at a rotation speed N _1, and the valve, the After the pump is started, when the temperature detected by the temperature sensor falls below the set value T ₁ (<T ₂ ), the pump is rotated at the rotation speed N _2.
(> N ₁ ) and means for closing the valve , wherein the pump is located at the lowest position,
The condenser is disposed at a slightly higher position, and the condenser
The tank is located lower and higher than the pump
Wherein the evaporator is disposed at the highest position . 2. A heat transport device in which a heat transport medium that has passed through a condenser on a heat source side is stored in a tank, and the heat transport medium in the tank is returned to the condenser through an evaporator on a use side by operating a pump. A bypass connected in parallel to the pump; a valve provided in the bypass; a means for detecting a difference between a suction side pressure and a discharge side pressure of the pump; Means for stopping the operation of the pump for a time and opening the valve , wherein the pump is disposed at the lowest position,
The condenser is located at a position slightly higher than the pump.
The tank is located below the compressor and above the pump.
And the evaporator is disposed at the highest position .