JPS6030421B2 - Cooling coil control method for air conditioner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for controlling an air conditioner that uses outside air, and particularly to a method for controlling a cooling coil when the enthalpy of outside air is greater than that at the blowout point.

FIG. 1 is an explanatory diagram of air conditions in a conventional method of controlling a cooling coil of an air conditioner.

Conventionally, in air conditioners equipped with cooling coils, heating coils, and humidifiers, outside air and part of the return air are mixed at a fixed ratio and then cooled or heated and humidified to obtain a blowout point into the air conditioning room. Ta. Therefore, if the enthalpy of the outside air is higher than that at the point of blowing into the air conditioning room, in Figure 1, part of the return air A and the outside air B are mixed at a constant ratio and the state point A and the state point A state point C after mixing is obtained on the line connecting B.

Furthermore, based on the indoor humidity signal, cooling and dehumidification are performed to the intersection D of the absolute humidity line including the blowout point E and the saturation line, and then heating is performed to the blowout point E. For this reason, the air conditioner has always been controlled through a process of cooling and heating to obtain the outlet point.

If the enthalpy of the outside air is greater than that at the outlet point, and the absolute humidity of the outside air is lower than that at the outlet point, the outside air B' is mixed with a portion of the return air A to obtain a state point C';C'
The blowout point E was obtained by cooling, dehumidifying and heating from the point to the intersection D between the absolute humidity line and the saturation line at the blowout point E, and humidifying as necessary.

For this reason, mutually contradictory operations such as cooling and heating were always performed, resulting in energy consumption.

SUMMARY OF THE INVENTION An object of the present invention is to provide a cooling coil control method for an air conditioner that can minimize the waste of energy due to the contradictory operations of cooling and heating, which is a drawback of the prior art.

This invention uses outside air whose enthalpy is larger than that at the outlet point, and when the absolute humidity of the outside air is higher than that at the outlet point, the intake amount of outside air is set to the minimum, and the amount of far air is reduced. After mixing with the air, it is cooled and dehumidified to the intersection of the absolute humidity line at the outlet point and the saturation line, and then heated to the outlet point. If the absolute humidity of the outside air is lower than that at the outlet point, the entire amount of outside air is taken in, After cooling to a point on the enthalpy line including the blowout point,
The cooling coil is controlled to humidify to the absolute humidity at the blowout point.

FIG. 2 shows an explanatory diagram of air conditions in the cooling coil control method for an air conditioner according to the present invention.

FIG. 3 is a system diagram of a cooling coil control method for an air conditioner according to the present invention.

It shows an air conditioning system consisting of a supply air duct 1, a return air duct 2, a mixing damper 3, an air conditioner 4, a cooling coil 5, a heating coil 6, a humidifying coil 7, an air blower 8, an air conditioning room 9, an exhaust fan 10, etc. .

In Fig. 2, if the enthalpy of the outside air is greater than that at the outlet point E into the air conditioning room and the absolute humidity of the outside air is higher than that at the outlet point E, the amount of outside air intake is minimized and the mixing damper 3 The state point C of the mixed air is obtained from the return air state V point A and the outside air state V point B, and the air is cooled from point C toward the intersection point D of the absolute humidity line and the saturation line at the outlet point. Perform dehumidification.

At this time, cooling and dehumidification are performed until the relative humidity reaches 100%. It is further heated from point D to obtain a blowout point E into the air conditioning room. In addition, in Figure 2, if the enthalpy of the outside air is greater than that at the outlet point E, and the absolute humidity of the outside air is lower than that at the outlet point E, the mixed amount of return air is set to zero and the entire amount of outside air is taken in. The opening degree of the mixing damper 3 is set to , and the cooling coil 5 cools the mixture to point F on the enthalpy line including the blowout point E.

At this time, the relative humidity is not cooled to 100%. After this cooling, humidification is performed to the absolute humidity of the blowing point E. As described above, the cooling coil 5 may perform only cooling or may perform cooling and dehumidification depending on the height relationship between the absolute humidity of the outside air and the absolute humidity of the outlet point.

In order to control this, the following phenomenon is used.

When outside air having an absolute humidity higher than the absolute humidity at the blowing point is taken in, the humidity in the air conditioning room increases. Furthermore, when outside air having an absolute humidity lower than the absolute humidity at the blowing point is taken in, the temperature of the air conditioning room changes. Utilizing this phenomenon, the dry bulb temperature and wet bulb temperature of the air conditioning room are detected by the dry bulb thermometer 14 and the wet bulb thermometer 15, respectively, and the relative humidity converter 1
Convert to relative humidity using 6.

The operation of the cooling coil is switched based on the deviation value between the relative humidity obtained by the dry bulb thermometer and green bulb thermometer installed in the air conditioning room and the set relative humidity, or the deviation value between the dry bulb temperature and the set temperature. The larger one is given priority for control.

The humidification control valve 12 is controlled to be fully closed during the cooling and dehumidification process.

The enthalpy and absolute humidity of the outside air are calculated by the microcomputer 17 from the dry bulb temperature and wet bulb temperature. The control device 18 controls the cooling control valve 13 of the cooling coil 5 and the humidification control valve 12 of the humidification pump 11 of the humidification coil 7 .

In this invention, when the enthalpy of outside air is greater than that at the outlet point, and the absolute humidity of the outside air is lower than that at the outlet point, the entire amount of outside air is taken in, so the dehumidification process is omitted.
It can be a cooling process only.

Therefore, in this case, it is not necessary to cool down to 100% relative humidity, but only to cool it halfway and then humidify it, so compared to the conventional method of cooling to 100% relative humidity and then reheating, there is no need to cool down to 100% relative humidity. Energy for reheating is no longer required, resulting in energy savings of approximately 1/2 throughout the year.

In addition, when controlling the operation of the cooling coil to switch to cooling/dehumidification or cooling only depending on the relationship between the absolute humidity of the outside air and the air outlet point, priority should be given to the larger of the temperature deviation or humidity deviation of the air conditioning room. The temperature and humidity inside the room are stable.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the air condition in a conventional cooling coil control method for an air conditioner, FIG. 2 is an explanatory diagram of the air condition in the cooling coil control method for an air conditioner according to the present invention, and FIG. FIG. 2 is a system diagram of a method for controlling cooling coils of an air conditioning system according to the invention. 1... Supply air duct, 2... Return air duct, 3
...Mixing damper, 4...Air conditioner, 5...
...Cooling coil, 7...Humidifying coil, 9...
... Air conditioning room, 12 ... Humidification control valve, 1
3... Cooling control valve, 14... Dry bulb thermometer, 15... Green bulb thermometer, 16... Relative humidity converter, 17... ...Microcomputer, 18...Control device. Figure l Figure 2 Figure 3

Claims (1)

[Scope of Claims] 1. In an air conditioner that uses outside air where the enthalpy of the outside air is greater than that at the outlet point, (a) the enthalpy of the outside air is greater than that at the outlet point, and the absolute humidity of the outside air is greater than that at the outlet point; If the temperature is higher, set the outside air intake to the minimum and mix it with a part of the return air, then cool and dehumidify the mixed gas to the intersection of the absolute humidity at the outlet point and the saturation line, and then heat it to the outlet point. do. (b) The enthalpy of the outside air is greater than that at the outlet point,
If the absolute humidity of the outside air is lower than that at the blowout point, the system is set to take in all the outside air, cools the outside air to a point on the enthalpy line that includes the blowout point, and then humidifies it to the absolute humidity at the blowout point. A cooling coil control method for an air conditioner, characterized in that: 2 In claim 1, switching between cooling only or cooling and dehumidification of the cooling coil is based on the relative humidity and the set relative humidity obtained by signals from a dry bulb thermometer and a wet bulb thermometer installed in the air conditioning room. A method for controlling a cooling coil of an air conditioner that gives priority to the larger of the deviation values between the dry bulb temperature and the set dry bulb temperature.