JP2021148301A - Air conditioning system - Google Patents

Abstract

To provide an air conditioning system capable of efficiently cooling air by using an external conditioner.SOLUTION: An air conditioning system includes: an external conditioner 1 having a first coil 3 to which a heating medium W1 is supplied from a first heat source machine 6 and that precools air A during cooling and a second coil 4 that is installed at a rear stage of the first coil 3, to which a heating medium W2 is supplied from a second heat source machine 7 and that further cools the air A during cooling; an air temperature sensor 10 measuring a temperature of the air A on an outlet side of the first coil 3; a heating medium temperature sensor 11 measuring a temperature of the heating medium W1 to be supplied from the first heat source machine 6 to the first coil 3; and a flow rate control section 12 controlling a flow rate of the heating medium W1 to be supplied from the first heat source machine 6 to the first coil 3. A precooling target value of the first coil 3 is set in accordance with the temperature of the heating medium W1 supplied from the first heat source machine 6 to the first coil 3.SELECTED DRAWING: Figure 2

Description

The present invention relates to an air conditioning system. In particular, it relates to an energy-saving air conditioning system related to outside air harmonization when introducing outside air indoors.

FIG. 1 schematically shows the configuration of an external air conditioner (outside air processing air conditioner) and its surroundings in an air conditioning system. The external air conditioner 1 is a device that takes in outside air, harmonizes it with a predetermined temperature and humidity, and sends it indoors. In the example shown here, a filter 2 that captures dust and purifies the air A, and the filter 2 It includes a coil (first coil 3 and second coil 4) provided in two stages in the rear stage, and a fan 5 provided in the rear stage of the coils 3 and 4.

In the first coil 3 and the second coil 4, a metal pipe through which a heat medium flows, fins protruding from the outer surface of the pipe, and air A flowing on the surface of the pipe and the fins. It is provided with a partition frame, and is provided from a heat source machine (first heat source machine 6 or second heat source machine 7) through a heat medium supply pipe (first heat medium supply pipe 8 or second heat medium supply pipe 9). Heat exchange is performed between the heat media W1 and W2 supplied respectively and the air A circulating in the external air conditioner 1 with the inside of its own frame as a part by the operation of the fan 5. An air temperature sensor 10 is provided between the first coil 3 corresponding to the front stage and the second coil 4 corresponding to the rear stage, and the temperature of the air A is measured at this position. Although the first heat medium supply pipe 8 and the second heat medium supply pipe 9 represent only the forward pipe in the figure, heat exchange is completed from both the first coil 3 and the second coil 4. The heat medium is derived from pipe tapping (not shown) and returned to the first heat source machine 6 or the second heat source machine 7 via each return pipe (not shown), and the heat medium itself carries heat while circulating. Of course.

A heat medium temperature sensor 11 is provided in the middle of the first heat medium supply pipe 8 to measure the temperature of the heat medium W1 supplied from the first heat source machine 6. Further, a flow rate adjusting unit 12 is provided at a position downstream of the heat medium temperature sensor 11 in the first heat medium supply pipe 8. The flow rate adjusting unit 12 is, for example, a two-way valve, and is supplied to the first coil 3 by appropriately changing the opening degree of the valve body provided in the flow path in the first heat medium supply pipe 8. By manipulating the flow rate of the heat medium W1, the amount of heat exchange between the heat medium W1 and the air A in the first coil 3 can be adjusted.

Similarly, a flow rate adjusting unit 13 is provided in the middle of the second heat medium supply pipe 9, and controls the flow rate of the heat medium W2 supplied to the second coil 4 to control the heat in the second coil 4. The amount of heat exchange between the medium W2 and the air A can be adjusted.

The air temperature sensor 10, the heat medium temperature sensor 11, and the flow rate adjusting units 12 and 13 are connected to the control device 14, respectively. The control device 14 is a device that automatically adjusts and operates the operation of the external air conditioner 1 after an operation signal is input from the outside, acquires the temperature of the air A measured by the air temperature sensor 10, and further heat medium. The temperature of the heat medium W1 measured by the temperature sensor 11 is acquired, and the flow rates of the heat media W1 and W2 in the flow rate adjusting units 12 and 13 are automatically operated.

Here, regarding the air conditioning system and the external air conditioner 1 shown in FIG. 1, components that are not directly related to the gist of the present invention described later (for example, a humidifier, a filter provided on the outlet side of the fan 5, an outside air intake louver or a duct, etc. The supply duct, indoor air-conditioning equipment, etc.) are not shown as appropriate.

Prior art documents related to this type of air conditioning system and external air conditioner include, for example, the following Patent Document 1. In Patent Document 1, the steam coil has two stages and is in charge of preheating and reheating, but the cold water coil has only one stage. Since there is only one normal cold heat source, this arrangement is used.

Japanese Unexamined Patent Publication No. 2004-245538

Regarding the external air conditioner 1 as shown in FIG. 1, especially in Japan, where the outside air is hot and humid from the middle period to the summer, the first heat source machine 6 and the second heat source machine 7 are used as cold heat sources, and the first coil 3 is used. And using the second coil 4 as a cooling coil is energetically advantageous in the following points.
When cooling is performed in such an external air conditioner 1, the first coil 3 can be used as a precooling coil and the second coil 4 can be used as a final cooling coil. That is, a medium temperature heat medium W1 (for example, about 10-15 ° C.) having a relatively high temperature is supplied from the first heat source machine 6 to the first coil 3, and is relative to the second heat source machine 7. A low-temperature heat medium W2 (for example, about 6 ° C.) having a relatively low temperature is supplied to the second coil 4. Then, the air A, which is the outside air, is precooled to a certain extent by the first coil 3 which is the front stage, and then further cooled by the second coil 4 which is the rear stage. For example, if the indoor air condition into which the outside air is introduced is a dry-bulb temperature of 23 ° C. and a relative humidity of 45%, the dew point temperature will be about 10 ° C. Dehumidification cannot be finally achieved unless the air is passed through the coil pipe. However, if the outside air at the peak of summer with a dry-bulb temperature of 33% and a relative humidity of 63% is used for cooling and dehumidifying halfway, a medium-temperature heat medium W1 is also effective. In order to use the heat medium as cooling water for other purposes other than dehumidification of air conditioning, the state where condensed water is generated around the heat exchanger may not be good at the temperature of the heat medium W2, and the heat medium W2 is used. Is often limited to the final dehumidification of the target dew point of the air supplied by controlling the temperature of the outside air in air conditioning. Then, the refrigerating energy of cold water up to a low temperature (for example, 6 ° C.) increases the work of the compressor per unit refrigerating heat amount of the refrigerating cycle, and the coefficient of performance: COP value is small and energy consumption is large. That is, since the first heat source machine 6 has a large COP, if the amount of cold water frozen by the first heat source machine 6 is large and the amount of cold water frozen by the second heat source machine 7 is small, the total COP is large. , Energy saving.

FIG. 2 conceptually shows the cooling operation of the air A in the external air conditioner 1 by using an air diagram (TX diagram). The saturated water vapor curve is indicated by the symbol L in the figure. The outside air before cooling is, for example, in the state of point P0 (dry-bulb temperature and absolute humidity) in FIG. 2, and the air A taken into the external air conditioner 1 passes through state point P1 from here and is in state point P2. It is cooled to the state of. In this process, the first coil 3 acting as the precooling coil is responsible for cooling from the point P0 to the point P1, and the second coil 4 acting as the final cooling coil is responsible for cooling from the point P1 to the point P2. Although described as a state point, ideally, it has the same meaning as cooling to the set point P2 (indoor dew point temperature target value) via the set point P1. In the cooling from the point P0 to the point P2, the air A removed by the condensation of water vapor due to the presence of a low temperature surface below the dew point of the air is further heated to the point P3 by a heater (not shown) as needed. NS. In this way, the air A is dehumidified to the point P2 that realizes the absolute humidity of the point P3, and by changing the sensible heat, the relative humidity is harmonized with the dry-bulb temperature of the point P3 and sent to the air conditioning equipment on the indoor side.

By the way, conventionally, when cooling is performed in the air conditioning system as described above, it is measured by the target value of the temperature of the air A cooled by the precooling coil (first coil 3) (that is, the air temperature sensor 10 of FIG. 1). The temperature target value; the X coordinate of the point P1 in FIG. 2; hereinafter referred to as “pre-cooling target value”) becomes the usual target value when feedback control is performed as, for example, PID control, and the target value. Is generally set as a fixed value. On the other hand, the heat transfer temperature of the heat medium W1 supplied from the first heat source machine 6 is not always constant due to the convenience of other cooling use when it is not only used for air conditioning, and may fluctuate depending on the case. This is because, in order to effectively utilize the cold heat generated by the first heat source machine 6 for various cooling targets, the heat medium W1 may be diverted to equipment other than the external conditioner 1 as necessary. For example, in order to use the heat medium W1 as cooling water for another purpose other than air conditioning, the temperature of the heat medium may be raised in consideration of the generation of condensed water around the heat exchanger. On the contrary, the temperature of the heat medium W1 may be lowered due to the pressure change in the refrigeration cycle of the first heat source machine 6 depending on the season.

Here, assuming that the precooling target value is a constant value regardless of the temperature of the heat medium W1, when the temperature of the heat medium W1 is low, the heat medium required to cool the air A in the state of the point P0 to the point P1. The amount of W1 is reduced. On the contrary, when the temperature of the heat medium W1 is high, the amount of the heat medium W1 required to cool the air A from the point P0 to the point P1 becomes large.

Generally, when the heat medium is cooled in the heat source machine, the higher the temperature of the heat medium supplied from the heat source machine, the better the energy efficiency in the heat source machine. That is, in the air conditioning system shown in FIG. 1, the cooling efficiency of the heat medium W1 in the first heat source machine 6 is higher than the cooling efficiency of the heat medium W2 in the second heat source machine 7. That is, when the coefficient of performance obtained by converting the amount of cold heat generated in the refrigeration cycle into KW and converting the work of the compressor into KW and dividing the amount of cold heat: COP, the COP in the first heat source machine 6 is the second heat source. It is larger than the COP in the machine 7. Therefore, from the viewpoint of energy efficiency in the heat source machines 6 and 7, when cooling the air A from the point P0 to the point P2, of the total cooling amount by the coils 3 and 4, the first coil 3 which is the precooling coil is used. It can be said that it is preferable to increase the cooling ratio as much as possible.

Here, if the temperature of the heat medium W1 is too low with respect to the pre-cooling target value (that is, if the pre-cooling target value is set too high with respect to the temperature of the heat medium W1), it is necessary for cooling from the point P0 to the point P1. Since the amount of the heat medium W1 is small, the amount ratio of the heat medium W1 and the heat medium W2 used for cooling from the point P0 to the point P2 is small for the heat medium W1. This is not preferable in terms of energy efficiency of the heat source machines 6 and 7, and if the operation is such that the supply amount of the heat medium W1 is increased and the supply amount of the heat medium W2 is decreased instead, the first heat source machine 6 And the total energy efficiency of the second heat source machine 7 is further improved.

On the other hand, a pump is used to supply the heat medium from the heat source machine, but in recent years, the pump operation of the heat source has been performed in consideration of the fact that the flow control mechanism such as the two-way valve on the load side is narrowed down in order to save energy. It is common to measure changes in pressure and control the flow rate of the central pump accordingly. The energy consumption of the pump increases as the supply amount of the heat medium increases according to the required heat amount on the secondary side expressed by the pressure of the heat medium system or the like. That is, from the viewpoint of suppressing the energy consumption of the pump (not shown) installed in the first heat medium supply pipe 8 in FIG. 1, the amount of the heat medium W1 supplied to the first coil 3 is not too large. Is preferable.

However, if the temperature of the heat medium W1 is too high with respect to the pre-cooling target value (that is, if the pre-cooling target value is set too low with respect to the temperature of the heat medium W1), the air A is cooled from the point P0 to the point P1. However, a large amount of heat medium W1 is required, the opening degree of the flow rate adjusting unit 12 is fully opened, the power of a pump (not shown) increases, and the energy consumed by the pump increases.

As described above, in the air conditioning system provided with the external air conditioner 1 as described above, the operation of the external air conditioner 1 has not always been optimized from the viewpoint of energy saving.

In view of such circumstances, the present invention aims to provide an air conditioning system capable of efficiently cooling air by an external air conditioner.

In the present invention, the heat medium is supplied from the first heat source machine, the first coil that precools the air during cooling, and the heat medium that is installed after the first coil and is supplied from the second heat source machine. An external conditioner including a second coil that further cools the air during cooling, an air temperature sensor that measures the temperature of the air on the outlet side of the first coil, and the first heat source machine. A heat medium temperature sensor for measuring the temperature of the heat medium supplied to one coil and a flow rate adjusting unit for adjusting the flow rate of the heat medium supplied from the first heat source machine to the first coil are provided. The air-conditioning system is configured to set a pre-cooling target value by the first coil according to the temperature of the heat medium supplied from the first heat source machine to the first coil. be.

In the air conditioning system of the present invention, the precooling target value can be set as a value higher by a certain temperature range with respect to the temperature of the heat medium supplied from the first heat source machine to the first coil.

In the air conditioning system of the present invention, the precooling target value can be set as an nth-order function with the temperature of the heat medium supplied from the first heat source machine to the first coil as a variable.

In the air conditioning system of the present invention, the temperature of the heat medium supplied from the first heat source machine to the first coil during cooling is the temperature of the heat medium supplied from the second heat source machine to the second coil. Can be set higher than the temperature of.

According to the air conditioning system of the present invention, it is possible to obtain an excellent effect that the air can be efficiently cooled by the external air conditioner.

It is the schematic which shows the structure around the external air conditioner in an air conditioning system simply. It is a diagram which conceptually shows the operation of air cooling in an air conditioning system.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Since the air conditioning system of this embodiment assumes the same configuration as that described in FIG. 1, it will be described with reference to FIG. Further, the operation of air cooling will also be described with reference to FIG.

The external regulator 1 includes a filter 2, first and second coils 3 and 4 provided after the filter 2, and a fan 5 provided after the coils 3 and 4.

Air A circulates in the external air conditioner 1 by the operation of the fan 5, and in the first coil 3 and the second coil 4, the first and second heat source machines 6 and 7 to the first and second Heat exchange is performed between the heat media W1 and W2 supplied through the heat medium supply pipes 8 and 9, respectively, and the air A. At the time of cooling, the air A is precooled in the first coil 3, and the air A is further cooled in the second coil 4 in the subsequent stage. An air temperature sensor 10 is provided between the first coil 3 corresponding to the front stage and the second coil 4 corresponding to the rear stage, and the temperature of the air A on the exit side of the first coil 3 is measured. There is.

A heat medium temperature sensor 11 is provided in the middle of the first heat medium supply pipe 8, and a flow rate adjusting unit 12 is provided at a position downstream of the heat medium temperature sensor 11. Further, a flow rate adjusting unit 13 is provided in the middle of the second heat medium supply pipe 9. The air temperature sensor 10, the heat medium temperature sensor 11, and the flow rate adjusting units 12 and 13 are connected to the control device 14, respectively.

Then, in the air conditioning system of the present embodiment, the target temperature (pre-cooling target value) of cooling by the pre-cooling coil (first coil 3) is variable as a cascade control based on the temperature measurement value of the heat medium W1 during cooling. It is characterized by the fact that it can be used.

That is, in the control device 14, as basic feedback control, based on the deviation between the measured value of the air temperature sensor 11 and the set value of the feedback system using the flow rate adjusting unit 12 as the operator, which is input to the control device 14. The calculation is performed so as to eliminate the deviation, and the control signal is output to the flow rate adjusting unit 12 which is an operator to control the valve opening degree of the flow rate adjusting unit 12. It is common to use PID control for this calculation. Here, the temperature of the heat medium W1 flowing through the first heat medium supply pipe 8 is grasped as the measured value of the heat medium temperature sensor 11, and the precooling target value is calculated based on the measured temperature of the heat medium W1. Continue to input and set in the control device 14 as the set value of the feedback system using the flow rate adjusting unit 12 as the operator (cascade control), and the deviation between the measured temperature of air A by the air temperature sensor 10 and the newly set precooling target value. Based on the above, the opening degree of the flow rate adjusting unit 12 is adjusted by the calculated control signal. The precooling target value can be set as an appropriate function with the temperature of the heat medium W1 as a variable. For example, a value higher than the measured value of the heat medium temperature sensor 11 by a certain temperature range (for example, +2 to 3 ° C.) may be set as the precooling target value, or the nth order such as a linear function or a quadratic function may be set. It may be a function (n = 1, 2, 3, ...). The pre-cooling target value may be updated, for example, by acquiring the measured value of the heat medium temperature sensor 11 at regular intervals and resetting the pre-cooling target value accordingly. Here, when the nth-order function is used to set the precooling target value, if the nth-order function uses the temperature of the heat medium W1 supplied from the first heat source machine 6 to the first coil 3 as a variable. , There are no particular restrictions on the conditions of each function.

In this way, when the temperature of the heat medium W1 is low, a correspondingly low temperature value is set as the precooling target value. When the temperature of the heat medium W1 becomes low, the target cooling amount by the first coil 3 increases, so that the supply amount of the heat medium W1 increases as compared with the case where the precooling target value is fixed. That is, in the control device 14, the opening degree of the flow rate adjusting unit 12 provided in the first heat medium supply pipe 8 is set large, and the heat medium W1 is adjusted so as to be supplied in a large amount to the first coil 3.

Further, if the amount of cooling by the first coil 3 increases, the temperature of the air A flowing from the first coil 3 to the second coil 4 decreases, so that the heat medium required for cooling in the second coil 4 decreases. The amount of W2 is reduced. The control device 14 adjusts the opening degree of the flow rate adjusting unit 13 according to the amount of cooling required by the second coil 4. As a result, the ratio of the cooling amount by the precooling coil (first coil 3) using the medium temperature heat medium W1 increases while the cooling amount of the entire external controller 1 does not change, and the final using the low temperature heat medium W2. The ratio of the amount of cooling by the cooling coil (second coil 4) is reduced. By using a large amount of the heat medium W1 having a temperature higher than that of the heat medium W2 and having good cooling efficiency, the energy efficiency of the heat source machines 6 and 7 is improved.

When the temperature of the heat medium W1 is high, a correspondingly high temperature value is set as the precooling target value. If the pre-cooling target value becomes high, the target cooling amount by the first coil 3 decreases. Therefore, the heat medium W1 when the temperature of the heat medium W1 is higher than that when the pre-cooling target value is fixed. The supply will be low. Since an excessive amount of heat medium W1 is not supplied to the first coil 3, an excessive increase in energy consumption required for the operation of the pump (not shown) provided in the first heat medium supply pipe 8 is prevented.

Such an operation corresponds to moving the precooling target value, that is, the X coordinate of the point P1 to the left or right (for example, the position of the point P1a or the point P1b) according to the temperature of the heat medium W1 in FIG. When the temperature of the heat medium W1 is low, the position of the point P1 is set to the point P1a accordingly, and the amount of cooling by the medium temperature heat medium W1 (the distance from the point P0 to the point P1 (P1a) in the X-axis direction) is increased. At the same time, the amount of cooling by the low-temperature heat medium W2 (distance in the X-axis direction from the point P1 (P1a) to the point P2) is reduced to improve the cooling efficiency of the heat source machines 6 and 7 and suppress the total energy consumption. On the other hand, when the temperature of the heat medium W1 is high, the position of the point P1 is set to the point P1b accordingly, the cooling amount by the heat medium W1 is reduced, the supply amount of the heat medium W1 is reduced, and the energy consumption by the pump (not shown) is reduced. It can be suppressed. In other words, the outside air is cooled by optimizing the distribution of the cooling amount by the first coil 3 and the first heat source machine 6 and the cooling amount by the second coil 4 and the second heat source machine 7. To save energy.

When performing such an operation, the capabilities of the coils 3 and 4 and the heat source machines 6 and 7 should be provided with redundancy. That is, the first coil 3 and the first heat source machine 6 provide a possible amount of cooling by precooling the air A from the position of the fluctuating point P0 to the position of the fluctuating point P1 (for example, the position of the point P1a). It needs to be designed so that it can be realized, and the second coil 4 and the second heat source machine 7 have air that can be assumed from the position of the fluctuating point P1 (for example, the position of the point P1b) to the position of the point P2. It is necessary to design so that the cooling amount by the final cooling of A can be realized.

As described above, in the air conditioning system of the present embodiment, the heat medium W1 is supplied from the first heat source machine 6, and the air A is precooled at the time of cooling to the first coil 3 and the subsequent stage of the first coil 3. An external air conditioner 1 provided with a second coil 4 which is installed, is supplied with a heat medium W2 from a second heat source machine 7, and further cools the air A during cooling, and air on the outlet side of the first coil 3. From the air temperature sensor 10 that measures the temperature of A, the heat medium temperature sensor 11 that measures the temperature of the heat medium W1 supplied from the first heat source machine 6 to the first coil 3, and the first heat source machine 6. A flow rate adjusting unit 12 for adjusting the flow rate of the heat medium W1 supplied to the first coil 3 is provided, and the first heat source machine 6 is provided with a flow rate adjusting unit 12 according to the temperature of the heat medium W1 supplied to the first coil 3. It is configured to set a pre-cooling target value by one coil 3. In this way, the distribution of the cooling amount in the first coil 3 and the second coil 4 can be optimized.

Further, in the air conditioning system of the present embodiment, the precooling target value is set as a value higher by a certain temperature range with respect to the temperature of the heat medium W1 supplied from the first heat source machine 6 to the first coil 3. Can be done.

Further, in the air conditioning system of the present embodiment, the precooling target value is an nth-order function (n = 1, 2) in which the temperature of the heat medium W1 supplied from the first heat source machine 6 to the first coil 3 is a variable. , 3, ...).

Further, in the air conditioning system of the present embodiment, the temperature of the heat medium W1 supplied from the first heat source machine 6 to the first coil 3 during cooling is supplied from the second heat source machine 7 to the second coil 4. It can be set higher than the temperature of the heat medium W2 to be formed.

Therefore, according to the air conditioning system of the present embodiment, the air conditioner 1 can efficiently cool the air.

The air conditioning system of the present invention is not limited to the above-described embodiment, and it goes without saying that various modifications can be made without departing from the gist of the present invention.

1 External conditioner 3 First coil 4 Second coil 6 First heat source machine 7 Second heat source machine 10 Air temperature sensor 11 Heat medium temperature sensor 12 Flow control unit A Air W1 Heat medium W2 Heat medium

Claims (4)

The first coil, which is supplied with a heat medium from the first heat source machine and precools the air during cooling,
An external conditioner installed after the first coil and provided with a second coil that is supplied with a heat medium from a second heat source machine and further cools the air during cooling.
An air temperature sensor that measures the temperature of the air on the outlet side of the first coil, and
A heat medium temperature sensor that measures the temperature of the heat medium supplied from the first heat source machine to the first coil, and
A flow rate adjusting unit for adjusting the flow rate of the heat medium supplied from the first heat source machine to the first coil is provided.
An air conditioning system characterized in that a precooling target value by the first coil is set according to the temperature of a heat medium supplied from the first heat source machine to the first coil. The precooling target value according to claim 1, wherein the precooling target value is set as a value higher by a certain temperature range with respect to the temperature of the heat medium supplied from the first heat source machine to the first coil. Air conditioning system. The precooling target value is set as an nth-order function (n = 1, 2, 3, ...) With the temperature of the heat medium supplied from the first heat source machine to the first coil as a variable. The air conditioning system according to claim 1, wherein the air conditioning system is characterized by the above. At the time of cooling, the temperature of the heat medium supplied from the first heat source machine to the first coil is set higher than the temperature of the heat medium supplied from the second heat source machine to the second coil. The air conditioning system according to any one of claims 1 to 3, wherein the air conditioning system is characterized by the above.

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