JP2020139711A - Air conditioning system - Google Patents

Abstract

To provide an air conditioning system which enables improvement of energy efficiency by inverter control.SOLUTION: An air conditioning system 10 according to the invention includes: a duct 11 for taking outdoor air into the system and supplying the air to an indoor space 60; a pre-cooling heat exchanger 20 disposed at the upstream side of the duct; a cooling heat exchanger 30 which is disposed at the downstream side of the pre-cooling heat exchanger and cools airflow to a predetermined absolute humidity; and a reheat heat exchanger 40 disposed at the downstream side of the cooling heat exchanger. The pre-cooling heat exchanger and the reheat heat exchanger are connected by a circulation pipe 50 in which a heat medium is circulated in a circulation pump 51. The circulation pump is inverter-controlled.SELECTED DRAWING: Figure 1

Description

The present invention relates to an air conditioning system that regulates the temperature and humidity of the outside air and supplies it indoors. More specifically, it absorbs the heat energy of the outside air and uses it for reheating the air after dehumidification. It is about an air conditioning system that can be used.

In pharmaceutical and food manufacturing factories, animal experiment facilities, plant cultivation factories, etc., it is required to adjust the indoor temperature and humidity. In this type of air conditioning system, in order to introduce air of the target humidity into the room, when the temperature and humidity of the outside air are high, for example, in summer, the outside air is cooled to the corresponding absolute humidity and reheated. By doing so, air of a desired temperature and humidity is supplied to the room.

In order to effectively utilize the energy required for cooling and reheating, for example, in Patent Document 1, precooling is performed once before cooling the outside air to absolute humidity. At this time, the heat exchange coil used for precooling and the heat exchange coil for reheating are connected by a circulation pipe through which the heat medium flows, and the heat medium in the circulation pipe is circulated by the circulation pump to precool. Sometimes it absorbs the heat energy of the outside air and uses the obtained heat energy for reheating.

Japanese Unexamined Patent Publication No. 07-233968

However, since the output of the circulation pump is constant, the absorption and reheating of heat energy are controlled as a matter of course and wasteful, and energy consumption cannot be suppressed.

An object of the present invention is to provide an air conditioning system capable of increasing energy efficiency by inverter control.

The air conditioning system according to the present invention
A duct that takes in outside air and supplies it indoors,
A precooling heat exchanger arranged on the upstream side of the duct,
A cooling heat exchanger located downstream of the precooling heat exchanger and cooling the air flow to a predetermined absolute humidity,
A reheat heat exchanger arranged on the downstream side of the cooling heat exchanger,
With
The precooling heat exchanger and the reheating heat exchanger are connected by a circulation pipe that circulates a heat medium by a circulation pump.
It ’s an air conditioning system,
The circulation pump is controlled by an inverter.

A third temperature sensor is provided on the downstream side of the reheat heat exchanger.
The circulation pump can be inverter-controlled based on the temperature detection value of the third temperature sensor.

A humidity sensor is installed in the room.
The circulation pump can be inverter-controlled based on the humidity detection value of the humidity sensor.

The precooling heat exchanger and the reheating heat exchanger can be switched and connected to a heat source arranged in parallel with the circulation pump.

A first temperature sensor for measuring the outside air temperature is provided on the upstream side of the precooling heat exchanger.
Based on the temperature detection value of the first temperature sensor, the circulation pump or the heat source can be switched and connected to the precooling heat exchanger and the reheating heat exchanger.

According to the air conditioning system of the present invention, the circulation pipe that thermally connects the precooling heat exchanger and the reheat heat exchanger controls the circulation pump that feeds the heat medium by the inverter. As a result, heat exchange between the precooling heat exchanger and the reheat heat exchanger can be performed under effective conditions with little heat loss, and the temperature can be adjusted at the time of reheating, so that energy efficiency can be achieved. Can be enhanced.

FIG. 1 is a schematic flow sheet of an air conditioning system according to the first embodiment of the present invention. FIG. 2 is a psychrometric chart. FIG. 3 is a graph showing the relationship between the room temperature and the frequency of the circulation pump. FIG. 4 is a schematic flow sheet of the air conditioning system according to the second embodiment of the present invention. FIG. 5 is a graph showing the relationship between the valve opening degree of the cold heat source and the dew point temperature. FIG. 6 is a graph showing the relationship between the temperature downstream of the duct and the frequency of the circulation pump. FIG. 7 is a graph showing the relationship between the temperature downstream of the duct and the valve opening degree of the two-way valve.

Hereinafter, the air conditioning system 10 of the present invention will be described with reference to the drawings.

<First Embodiment>
As shown in FIG. 1, the air conditioning system 10 of the present invention is a system that supplies outside air to a space 60 (also referred to as “indoor” as appropriate) controlled by air conditioning. Examples of the air-conditioned space 60 include a pharmaceutical and food manufacturing factory, an animal experiment facility, and a plant cultivation factory.

In the air-conditioning system 10 of the first embodiment, when the temperature and humidity are higher than the space 60, such as in summer, the outside air is once pre-cooled and then cooled to absolute humidity to adjust the humidity, and the humidity-adjusted air is released. It is reheated and supplied to the room 60.

As a specific configuration, the air conditioning system 10 is provided with an air intake 12 communicating with the outside air on the upstream side, and a precooling heat exchanger 20 is provided in the duct 11 in which the air outlet 13 on the downstream side communicates with the room 60 in order from the upstream side. , The cooling heat exchanger 30 and the reheat heat exchanger 40 are arranged and configured. The duct 11 is provided with a fan or a filter (not shown), and the outside air filtered by the filter is introduced into the duct 11 by the operation of the fan.

For example, the precooling heat exchanger 20 can be composed of a precooling coil 21, the cooling heat exchanger 30 can be composed of an outside air processing air conditioner 31, and the reheating heat exchanger 40 can be composed of a reheating coil 41.

The precooling coil 21 and the reheating coil 41 form a closed circuit connected by a circulation pipe 50. A heat medium such as water or antifreeze is housed in the closed circuit of the circulation pipe 50, and the heat medium is circulated in the closed circuit by the circulation pump 51. The circulation pump 51 is inverter-controlled based on a signal from the humidity indicator HIC, which will be described later.

Further, the room 60 controlled by air conditioning is provided with an air conditioner 61, and the temperature of the room 60 is adjusted to a predetermined temperature.

In the air conditioning system 10, a first temperature sensor T1 for measuring the outside air temperature is arranged on the upstream side of the precooling coil 21, a humidity sensor H is arranged in the room 60, and a second temperature sensor T2 is arranged on the downstream side of the outside air processing air conditioner 31. There is. The value of the first temperature sensor T1 is used for starting / stopping control of the circulation pump 51, and the humidity indicator HIC controls the output of the circulation pump 51 by an inverter based on the value of the humidity sensor H. The value of the second temperature sensor T2 is used for adjusting the output of the outside air processing air conditioner 31.

However, in the air conditioning system 10 of the first embodiment, in a situation where the temperature measured by the first temperature sensor T1 is higher than a predetermined temperature, the circulation pump 51 and the outside air processing air conditioner 31 are operated while the outside air is ducted 11 By introducing it into the room, a humidity-controlled air flow is supplied to the room 60, and the temperature of the room 60 is kept constant by the operation of the air conditioner 61. If the value of the first temperature sensor T1 is lower than the predetermined temperature, the circulation pump 51 cannot be reheated, so the circulation pump 51 is stopped.

FIG. 2 is a psychrometric chart, and points A to D in FIG. 2 indicate states of air flow at each position of points A to D in the air conditioning system 10 of FIG. As shown in FIGS. 1 and 2, the outside air (point A: absolute humidity H1, temperature t1) is first precooled by passing through the precooling coil 21, and the air flow (point B) having a temperature lower than that of point A. become. At this time, the heat energy taken from the outside air is accumulated in the reheating coil 41 by the movement of the heat medium from the precooling coil 21. Although the point B is on the saturation line of 100% relative humidity in FIG. 2, it may be shifted to the left or right depending on the cooling capacity of the precooling coil 21.

The air flow (point B: absolute humidity H1) that has passed through the precooling coil 21 enters the outside air processing air conditioner 31, is further cooled, and points B (temperature t2, absolute humidity) along the saturation line where the relative humidity becomes 100%. From H1), the absolute humidity H2 and the temperature t3 (point C) corresponding to the relative humidity with respect to the target room temperature are adjusted. As a result, the air flow discharged from the outside air processing air conditioner 31 becomes an air flow whose absolute humidity is adjusted to H2.

Subsequently, the air flow discharged from the outside air processing air conditioner 31 is sent to the reheating coil 41 to be reheated. Specifically, the reheating coil 41 raises the temperature of the air flow by the heat energy taken from the outside air by the precooling coil 21 (point D: temperature t4, absolute humidity H2) and supplies it to the room 60.

In the room 60, by operating the air conditioner 61 so as to have a predetermined set temperature, the air flow of the absolute humidity H2 is temperature-adjusted and maintained at a desired set temperature and humidity. When there is no heat loss, the heat energy of precooling and the heat energy of reheating are the same, and the temperature rises (t4-t3) by reheating by the precooling temperature (t1-t2).

In the air conditioning system 10 having the above configuration, the circulation pump 51 is inverter-controlled while adjusting the frequency based on the humidity of the room 60 as shown in the graph shown in FIG. Specifically, when the humidity measured by the humidity sensor H in the room 60 rises (ΔSP2), the humidity indicator HIC raises the operating frequency of the circulation pump 51 to increase the output of the circulation pump 51. As a result, the heat energy taken from the air flow in the precooling coil 21 increases, and the heat energy returned to the air flow by the reheating coil 41 also increases, so that the temperature of the air flow supplied to the room 60 rises. , The temperature of the room 60 also rises. As a result, the relative humidity of the room 60 decreases, but the air conditioner 61 operates to adjust the temperature of the room 60 to be constant, so that the temperature and humidity of the room 60 are finally kept constant.

The humidity indicator HIC has a minimum operating frequency of, for example, 15 hertz, and when the humidity rise (ΔSP2) is small, the circulation pump 51 can be stopped to reduce energy consumption.

According to the present embodiment, by controlling the circulation pump 51 with an inverter, the transfer of heat energy in the precooling coil 21 and the reheating coil 41 can be controlled and the amount of reheat can be adjusted, so that the energy efficiency can be improved as much as possible. Can be done.

<Second Embodiment>
In the second embodiment, as shown in FIG. 4, the precooling coil 21 and the reheating coil 41 are connected by an inverter-controlled circulation pump 51 as in the first embodiment, and the precooling coil 21 and the reheating coil 41 are connected. A heat source 56 such as a boiler or a heat pump chiller is connected in parallel with the circulation pump 51 as a separate heat source. Valves 57 and 58 are arranged between the heat source 56 and the precooling coil 21 and between the heat source 56 and the reheat coil 41, respectively, so that the flow of the heat medium from the heat source 56 can be permitted or blocked. Further, a two-way valve 53 is arranged in the circulation pipe 50 so that the amount of heat medium to be distributed can be adjusted. The cooling heat exchanger 30 can employ a cold heat source 33 such as water supply, and a valve 34 for adjusting the flow rate is provided in the pipe 35 connecting the cold heat source 33 and the cooling coil 32. Since the room 60 to be controlled by air conditioning is the same as in FIG. 1, illustrations and the like are omitted. Further, the same reference numerals as those of the first embodiment mean the same or equivalent members, and the description thereof will be omitted as appropriate.

As shown in FIG. 4, the air conditioning system 10 of the second embodiment has a first temperature sensor T1 for measuring the outside air temperature, a dew point temperature sensor DP1 for measuring the dew point temperature on the downstream side of the reheating coil 41, and a third temperature sensor. Equipped with T3. Then, the temperature indicator TIC1 controls the start / stop of the circulation pump 51, the opening / closing of the valves 57 and 58, and the start / stop of the heat source 56 via the relay R with reference to the temperature of the first temperature sensor T1. , A signal for controlling the two-way valve 53 is transmitted to the temperature indicator TIC3. The temperature indicator TIC3 refers to the temperature of the third temperature sensor T3, and in the case of control by the circulation pump 51, the circulation pump 51 is controlled by the inverter, and in the case of control by the heat source 56 and the two-way valve 53, as described later. , Adjust the valve opening. Further, the dew point temperature sensor DP1 is connected to the dew point temperature indicator DIC, and the dew point temperature indicator DIC adjusts the opening degrees of the valves 57 and 58 based on the measured dew point temperature.

However, when the outside air temperature T1 is higher than the set temperature SP1 (SP1 can be set x ° C. higher than T2 depending on the capacity of the circulation pump 51), the two-way valve 53 is fully opened. Further, the circulation pump 51 and the cold heat source 33 are operated under the condition that the valves 57 and 58 are closed and the heat source 56 does not act. As a result, as in the first embodiment, the air is precooled or heated by the precooling coil 21, and the cooling coil 32 on the downstream side is cooled by the cooling heat source 33 to adjust the absolute humidity of the air flow. As shown in FIG. 5, the valve 34 of the cold heat source 33 can be adjusted in absolute humidity by adjusting the opening degree to increase as the dew point temperature increases.

Also in this embodiment, the circulation pump 51 is inverter-controlled so that the temperature T3 of the air supplied to the room 60 by the reheating coil 41 becomes the target temperature SP3. As shown in FIG. 6, the inverter control is controlled so as to repeat the operation of operating the circulation pump 51 at the lowest frequency N hertz when the temperature T3 approaches the target temperature SP3 and further stopping the circulation pump 51 when the temperature T3 exceeds, for example, S ° C. Just do it. By controlling the circulation pump 51 with an inverter in this way, the movement of heat energy in the precooling coil 21 and the reheating coil 41 can be controlled and the amount of reheating can be adjusted, so that the energy efficiency can be improved as much as possible.

When the outside air temperature T1 is lower than the set temperature SP1 (temperature T2 + x ° C.) as in the summer, the circulation pump 51 cannot be reheated, so the circulation pump 51 is stopped and switched to the heat source 56. .. If the outside air temperature T1 is higher than the temperature T2, heat exchange is possible, but in consideration of the energy consumption by the circulation pump 51, if the outside air temperature T1 is not higher than the temperature T2 by x ° C. or more, the circulation pump 51 is stopped. I'm letting you.

By opening the valves 557 and 58 to operate the heat source 56, the temperature of the reheating coil 41 is forcibly raised. As shown in FIG. 7, the reheat amount is controlled by referring to the value of the third temperature sensor T3 and controlling so that the valve opening degree of the two-way valve 53 decreases as the temperature rises, and the third temperature sensor T3 The temperature may be controlled to be constant. As a result, heat exchange can be performed by the reheating coil 41 not only in summer but also in all seasons, and humidity can be adjusted by the air conditioning system 10 with improved energy efficiency.

The description of the above examples is for explaining the present invention, and should not be understood so as to limit or reduce the scope of the invention described in the claims. Further, the configuration of each part of the present invention is not limited to the above embodiment, and it goes without saying that various modifications can be made within the technical scope described in the claims.

10 Air conditioning system 20 Precooling heat exchanger 21 Precooling coil 30 Cooling heat exchanger 31 Outside air processing air conditioner 40 Reheat heat exchanger 41 Reheating coil 51 Circulation pump

Claims (5)

A duct that takes in outside air and supplies it indoors,
A precooling heat exchanger arranged on the upstream side of the duct,
A cooling heat exchanger located downstream of the precooling heat exchanger and cooling the air flow to a predetermined absolute humidity,
A reheat heat exchanger arranged on the downstream side of the cooling heat exchanger,
With
The precooling heat exchanger and the reheating heat exchanger are connected by a circulation pipe that circulates a heat medium by a circulation pump.
It ’s an air conditioning system,
The circulation pump is inverter controlled.
An air conditioning system that features that. A third temperature sensor is provided on the downstream side of the reheat heat exchanger.
The circulation pump is inverter-controlled based on the temperature detection value of the third temperature sensor.
The air conditioning system according to claim 1. A humidity sensor is installed in the room.
The circulation pump is inverter-controlled based on the humidity detection value of the humidity sensor.
The air conditioning system according to claim 1 or 2. The precooling heat exchanger and the reheating heat exchanger can be switched and connected to a heat source arranged in parallel with the circulation pump.
The air conditioning system according to any one of claims 1 to 3. A first temperature sensor for measuring the outside air temperature is provided on the upstream side of the precooling heat exchanger.
Based on the temperature detection value of the first temperature sensor, the circulation pump or the heat source is switched and connected to the precooling heat exchanger and the reheating heat exchanger.
The air conditioning system according to claim 4.

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