Air conditioning apparatus and air conditioning control method

1. An air conditioning apparatus comprising:

a first acquisition section that acquires a first absolute humidity indicating a target absolute humidity determined from a first temperature indicating a previously set temperature and a first relative humidity indicating a previously set relative humidity;

a second acquisition section that acquires a dew-point temperature determined from the first temperature and the first relative humidity;

a third acquisition section that acquires a second absolute humidity indicating an absolute humidity inside a room, the absolute humidity being determined from a second temperature indicating a temperature inside the room and a second relative humidity indicating a relative humidity inside the room;

a heat exchanger that exchanges heat between air inside the room and a refrigerant;

an air blower that blows air cooled by the heat exchanger;

an air outlet for blowing air blown by the air blower into the room; and

a control section that

determines whether the difference between the second temperature and an outside temperature is greater than a threshold,

switches the air conditioning apparatus from a cooling operation mode to a dehumidification operation mode that stops air-blowing of the air blower, and closes the air outlet in response to the determination that the difference between the second temperature and the outside temperature becomes greater than the predetermined threshold,

determines whether the second absolute humidity is higher than the first absolute humidity,

determines whether the difference between the acquired dew-point temperature and the temperature of the heat exchanger is greater than a second predetermined threshold, and

cools the heat exchanger so that the temperature of the heat exchanger becomes equal to the acquired dew-point temperature in the dehumidification operation mode in response to the determination that the second absolute humidity is higher than the first absolute humidity and the determination that the difference between the acquired dew-point temperature and the temperature of the heat exchanger is greater than a second predetermined threshold.

2. The air conditioning apparatus according to claim 1 , wherein

the first acquisition section includes a first calculation section that acquires the first temperature and the first relative humidity and calculates the first absolute humidity from the first temperature and the first relative humidity,

the second acquisition section includes a second calculation section that acquires the first temperature and the first relative humidity and calculates the dew-point temperature from the first temperature and the first relative humidity, and

the third acquisition section includes a third calculation section that acquires the second temperature and the second relative humidity and calculates the second absolute humidity from the second temperature and the second relative humidity.

3. The air conditioning apparatus according to claim 1 , wherein

the control section continues cooling of the heat exchanger while the second absolute humidity is higher than the first absolute humidity.

4. The air conditioning apparatus according to claim 1 , wherein

the control section continues cooling of the heat exchanger while a temperature of the heat exchanger is not lower than the dew-point temperature.

5. The air conditioning apparatus according to claim 1 , further comprising a fourth acquisition section that acquires a third temperature indicating a temperature outside the room,

wherein the control section starts the dehumidification operation when the first temperature or the second temperature is higher than the third temperature.

6. The air conditioning apparatus according to claim 1 , wherein

the control section cools the heat exchanger so that a temperature of the heat exchanger falls within a predetermined range including the dew-point temperature after the second absolute humidity reaches the first absolute humidity in the dehumidification operation.

7. The air conditioning apparatus according to claim 1 , further comprising a first memory configured to store an absolute humidity translation table listing a plurality of values for absolute humidity, relative humidity, and temperature and associating each value of absolute humidity with specific values for relative humidity and temperature, wherein

the first acquisition section acquires from the absolute humidity translation table stored in the first memory the first absolute humidity indicating the target absolute humidity determined from the first temperature stored in the absolute humidity translation table in the first memory indicating the previously set temperature and the first relative humidity stored in the absolute humidity translation table in the first memory indicating the previously set relative humidity, and

the third acquisition section acquires from the absolute humidity translation table in the first memory the second absolute humidity indicating the absolute humidity inside the room, the absolute humidity being determined from the second temperature stored in the absolute humidity translation table in the first memory indicating the temperature inside the room and the second relative humidity stored in the absolute humidity translation table in the first memory indicating the relative humidity inside the room.

8. The air conditioning apparatus according to claim 1 , further comprising a second memory configured to store a dew-point temperature translation table listing a plurality of values for the dew-point temperature, the room temperature, and relative humidity, and associating each value of the dew-point temperature with specific values for relative humidity and room temperature, wherein

the second acquisition section acquires from the dew-point temperature translation table stored in the second memory the dew-point temperature determined from the first temperature and the first relative humidity.

9. An air conditioning control method for controlling an air conditioning apparatus using a processor, the air conditioning apparatus including a heat exchanger that exchanges heat between air inside a room and a refrigerant, an air blower that blows air cooled by the heat exchanger, and an air outlet for blowing air blown by the air blower into the room, the air conditioning control method comprising:

acquiring a first absolute humidity indicating a target absolute humidity determined from a first temperature indicating a previously set temperature and a first relative humidity indicating a previously set relative humidity;

acquiring a dew-point temperature determined from the first temperature and the first relative humidity;

acquiring a second absolute humidity indicating an absolute humidity inside the room, the absolute humidity being determined from a second temperature indicating a temperature inside the room and a second relative humidity indicating a relative humidity inside the room;

determining whether the difference between the second temperature and an outside temperature is greater than a threshold,

switching the air conditioning apparatus from a cooling operation mode to a dehumidification operation mode that stops air-blowing of the air blower, and closes the air outlet in response to the determination that the difference between the second temperature and the outside temperature becomes greater than the predetermined threshold,

determining whether the second absolute humidity is higher than the first absolute humidity,

determining whether the difference between the acquired dew-point temperature and the temperature of the heat exchanger is greater than a second predetermined threshold, and

cooling the heat exchanger so that the temperature of the heat exchanger becomes equal to the acquired dew-point temperature in the dehumidification operation mode in response to the determination that the second absolute humidity is higher than the first absolute humidity and the determination that the difference between the acquired dew-point temperature and the temperature of the heat exchanger is greater than a second predetermined threshold.

10. The air conditioning control method according to claim 9 , wherein the air conditioning apparatus further comprises a first memory configured to store an absolute humidity translation table listing a plurality of values for absolute humidity, relative humidity, and temperature and associating each value of absolute humidity with specific values for relative humidity and temperature, wherein

the acquiring of the first absolute humidity acquires from the absolute humidity translation table stored in the first memory the first absolute humidity indicating the target absolute humidity determined from the first temperature stored in the absolute humidity translation table in the first memory indicating the previously set temperature and the first relative humidity stored in the absolute humidity translation table in the first memory indicating the previously set relative humidity, and

the acquiring of the second absolute humidity acquires from the absolute humidity translation table in the first memory the second absolute humidity indicating the absolute humidity inside the room, the absolute humidity being determined from the second temperature stored in the absolute humidity translation table in the first memory indicating the temperature inside the room and the second relative humidity stored in the absolute humidity translation table in the first memory indicating the relative humidity inside the room.

11. The air conditioning control method according to claim 9 , wherein the air conditioning apparatus further includes a second memory configured to store a dew-point temperature translation table listing a plurality of values for the dew-point temperature, the room temperature, and relative humidity, and associating each value of the dew-point temperature with specific values for relative humidity and room temperature, wherein

the dew-point temperature acquiring acquires from the dew-point temperature translation table stored in the second memory the dew-point temperature determined from the first temperature and the first relative humidity.