US20140069131A1

US20140069131A1 - Air conditioning system

Info

Publication number: US20140069131A1
Application number: US13/614,305
Authority: US
Inventors: Hirotaka Masui
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2012-09-13
Filing date: 2012-09-13
Publication date: 2014-03-13
Also published as: WO2014041896A1; EP2913602A1; JPWO2014041896A1

Abstract

An air-conditioning system including an air-conditioning apparatus having a compressor circulating a refrigerant, and an outdoor unit and an indoor unit performing air conditioning of an air-conditioned room; outside air introduction means supplying air outside the air-conditioned room; outside air temperature detection means detecting a temperature outside the air-conditioned room; human body position detection means detecting a user in the air-conditioned room; target-room-temperature determination means determining a user number and/or a variation of the user number in the air-conditioned room on the basis of the detection of the human body position detection means and determining a target room temperature; and cooling-operation-method determination means determining whether to operate the air-conditioning apparatus or to operate the outside air introduction means on the basis of the target room temperature and the temperature outside the air-conditioned room.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to an air conditioning system that air conditions an air-conditioned space.
2. Description of the Related Art
In the related art, there is an air conditioning system that performs a cooling/heating operation so that a comfortable temperature is reached when a motion sensor detects presence of an occupant in a room and that performs a low load operation when the motion sensor detects no occupant in the room (see Patent Literature 1, for example). Further, when a temperature of air (outside air) of a non-air-conditioned space (outdoor) is lower than a temperature of an air-conditioned space, a typical outside air cooling operation performs a cooling operation, for example, by suspending an operation of a compressor in order to stop an operation performed with a refrigerant circuit and by introducing the outside air into the conditioned space.

CITATION LIST

Patent Literature

Patent Literature 1: Japanese Unexamined Patent Application Publication No. 11-006644 (FIG. 1)

BRIEF SUMMERY OF THE INVENTION

Technical Problem

A known air conditioning system, such as the one in Patent Literature 1, is capable of performing energy saving operations while there is no occupant in a room; however, when there is an occupant in the room, operation is performed with a fixed target room temperature.
Here, a comfortable temperature for an occupant who has entered the room from a hot outdoor area and a comfortable temperature for an occupant who has been in the room for a long time and is sufficiently cooled are, in most cases, different. If the target room temperature is set low to suit the occupant who has entered the room, it will be cold for the occupant who has been in the room and it will cause energy to be lost due to over cooling. Whereas, if the target room temperature is set high, it will be hot for the former occupant, disadvantageously impairing comfortability.
Further, although the outside air cooling operation does not require the operation of the refrigerant circuit in which the compressor is driven, when the outside air temperature is relatively high without much difference with the target room temperature, a large amount of outside air needs to be introduced (supplied). Accordingly, conveyance power for the outside air increases, resulting in increase of power consumption; hence, energy saving is disadvantageously hindered. In particular, if the outside air is introduced through a long duct, the conveyance power loss is increased markedly. Further, when the outside air temperature is excessively low, the outside air cooling operation cannot be performed due to possibility of dew condensation and the like. Accordingly, the range of the outside air temperature allowing performance of the outside air cooling operation is limited; hence, sufficient advantages are not obtained throughout the year.
The invention addresses to the above disadvantages and an object thereof is to provide an air conditioning system that is capable of achieving energy saving while maintaining a temperature corresponding to a state of the occupants in an air-conditioned space.

Solution to Problem

An air-conditioning system of the invention includes an air-conditioning apparatus that has a compressor that circulates a refrigerant and that performs air conditioning of an air-conditioned space; a fan that supplies air outside the air-conditioned space; outside air temperature detection means that detects a temperature outside the air-conditioned space; heat source detection means that detects a heat source object in the air-conditioned space;
target-room-temperature determination means that determines a user number and/or a variation of the user number in the air-conditioned space on the basis of a detection of the heat source detection means and that determines a target room temperature that is a temperature target of the air-conditioned space; and cooling-operation-method determination means that determines whether to operate the air-conditioning apparatus or to operate the fan on the basis of the target room temperature and the temperature outside the air-conditioned space.

Advantageous Effects of Invention

According to the invention, an energy saving operation using the outside air can be performed while maintaining the temperature to a temperature corresponding to the state of the occupants in the air-conditioned space by determining the target room temperature on the basis of the number of occupants in the air-conditioned space and variation of the number thereof and by determining whether to operate the air-conditioning apparatus or the fan on the basis of the target room temperature and the like.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a schematic diagram illustrating an air-conditioning system according to Embodiment 1 of the invention;

FIG. 2 is a block diagram illustrating an air-conditioning apparatus according to Embodiment 1 of the invention;

FIG. 3 is a diagram illustrating a relationship between users of an air-conditioned room and a detection signal of human body position detection means according to Embodiment 1 of the invention;

FIG. 4 is a diagram illustrating a flowchart of a procedure that is performed by target-room-temperature determination means according to Embodiment 1 of the invention;

FIG. 5 is a diagram illustrating power consumed when outside air introduction means is driven and when a refrigerant circuit is operated;

FIG. 6 is a diagram related to a process of cooling-operation-method determination means according to Embodiment 1 of the invention and is a diagram illustrating the relationship between the cooling operation, when the level of the occupant number is high or when the level has been increased, and the outside air temperature;

FIG. 7 is a diagram related to the process of the cooling-operation-method determination means according to Embodiment 1 of the invention and is a diagram illustrating the relationship between the cooling operation, when the level of the occupant number is low, intermediate, or zero, or when the level has been decreased or there has been no change, and the outside air temperature;

FIG. 8 is a schematic diagram illustrating an air-conditioning system according to Embodiment 3 of the invention; and

FIG. 9 is a diagram illustrating a flowchart of a procedure that is performed by the cooling-operation-method determination means according to Embodiment 3 of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Subsequently, Embodiments of the invention will be described with reference to the drawings. Note that the configuration, the operation, and the like of the air conditioning system of the invention are not limited to those that are described in the subsequent Embodiments.

Embodiment 1

FIG. 1 is a schematic diagram illustrating an air-conditioning system according to Embodiment 1 of the invention. Referring to FIG. 1, the air conditioning system of Embodiment 1 includes an air-conditioning apparatus having an outdoor unit 1 and an indoor unit 3 connected by refrigerant pipes 2. The indoor unit 3 is disposed in an air-conditioned room 4. Further, the air-conditioned room 4 is provided with outside air introduction means 6 such as a fan, an outside air introduction duct 7, human body position detection means (human body position detection sensor) 5, and room temperature detection means (room temperature detection sensor) 9. Furthermore, outside air temperature detection means (outside air temperature detection sensor) 10 and a controller 11 are provided outside the air-conditioned room 4.
FIG. 2 is a block diagram illustrating the air-conditioning apparatus according to Embodiment 1 of the invention. The air-conditioning apparatus includes a refrigerant circuit, which circulates a refrigerant between the outdoor unit 1 and the indoor unit 3, and performs air conditioning of the air-conditioned room 4. In Embodiment 1, description is given assuming that air conditioning is performed with a cooling operation that cools the air-conditioned room 4. As illustrated in FIG. 2, the outdoor unit 1 of Embodiment 1 includes various devices (means) such as a compressor 101, a four-way valve 102, an outdoor side heat exchanger 103, and an outdoor side fan 104.
The compressor 101 compresses and discharges the suction refrigerant. Further, the outdoor side heat exchanger 103 exchanges heat between the refrigerant and air (outdoor air). Here, the outdoor side heat exchanger 103 of Embodiment 1 functions, for example, as an evaporator during a heating operation; exchanges heat between a low-pressure refrigerant, which has flowed therein from the refrigerant pipe 2, and the air; and evaporates and gasifies the refrigerant. Further, the outdoor side heat exchanger 103 functions as a condenser during a cooling operation; exchanges heat between a refrigerant, which has flowed from the four-way valve 102 side and that has been compressed in the compressor 101, and air; and condenses and liquefies the refrigerant. Furthermore, the outdoor side fan 104 sends in air from the outside of the air-conditioned room 4 so that efficient heat exchange is performed between the refrigerant and the air. The four-way valve 102 switches the flow of the refrigerant between a flow for a cooling operation and a flow for a heating operation in accordance with an instruction from the controller 11.
Meanwhile, the indoor unit 3 includes an indoor side heat exchanger 301, and indoor side expansion device (expansion valve) 302, and an indoor side fan 303. The indoor side heat exchanger 301 exchanges heat between the refrigerant and the air in the air-conditioned room 4. The indoor side heat exchanger 301 functions, for example, as a condenser during a heating operation; exchanges heat between the refrigerant, which has flowed therein from the refrigerant pipe 2, and the air; condenses and liquefies (or into a two-phase gas-liquid state) the refrigerant, and makes the refrigerant flow out therefrom. The indoor side heat exchanger 301 functions as an evaporator during a cooling operation; exchanges heat between the refrigerant, which has been turned into a low-pressure state with the indoor side expansion device 302, and the air; evaporates and gasifies the refrigerant by having the refrigerant remove heat from the air; and makes the refrigerant flow out therefrom. Further, the indoor unit 3 is provided with the indoor side fan 303 to control the flow of air that performs heat exchange.
The human body position detection means 5 serving as a heat source sensor is, for example, an infrared sensor. For example, the human body position detection means 5 scans the entire air-conditioned room 4, detects a two-dimensional temperature distribution of the entire air-conditioned room 4, and transmits a signal to the controller 11. Here, although the human body position detection means 5 scans and detects the two-dimensional temperature distribution of the entire air-conditioned room 4, the invention is not limited to this. For example, an array of infrared sensors may constitute the human body position detection means 5 such that detection of the two-dimensional temperature distribution of the entire air-conditioned room 4 is carried out without any scanning.
The room temperature detection means 9 that serves as an indoor air temperature sensor detects the air temperature in the air-conditioned room 4 and transmits a signal to the controller 11. Further, the outside air temperature detection means 10 that serves as an outside air temperature sensor detects the air (outside air) temperature (outside air temperature) outside the air-conditioned room 4 and transmits a signal to the controller 11.
The outside air introduction means 6 includes a fan, drives the fan, and sends outside air into the air-conditioned room 4 from the outside of the air-conditioned room 4 through the outside air introduction duct 7.
Each signal line 8 is a line for communicating with the controller 11. Here, in Embodiment 1, a signal line 8 a is a line for transmitting a signal related to a detection of the outside air temperature detection means 10. A signal line 8 b is a line for communicating between the indoor unit 3 and the controller 11. A signal line 8 c is a line for transmitting a signal related to a detection of the room temperature detection means 9. A signal line 8 d is a line for transmitting a signal related to a detection of the human body position detection means 5. A signal line 8 e is a line for communicating between the outside air introduction means 6 and the controller 11.
The controller 11 controls each of the components of the air conditioning system. In Embodiment 1, the controller 11 includes target-room-temperature determination means 12 and cooling-operation-method determination means 13. The target-room-temperature determination means 12 performs a determination process of the target room temperature in the air-conditioned room 4 in correspondence with the signal sent from the human body position detection means 5. Details of the process will be described below. Further, the cooling-operation-method determination means 13 performs a determination process of whether to perform a cooling operation with the air-conditioning apparatus (refrigerant circuit) or to perform an outside air cooling operation that makes the outside air flow into the air-conditioned room 4 from the outside air introduction means 6 on the basis of the target room temperature that the target-room-temperature determination means 12 has determined and the outside air temperature related to the detection of the outside air temperature detection means 10. Furthermore, the operation of each component is controlled such that the room temperature related to the detection of the room temperature detection means 9 becomes a target room temperature that the target-room-temperature determination means 12 has determined.
FIG. 3 is a diagram illustrating relationships between users 20 (20 a, 20 b, 20 c, 20 d) of the air-conditioned room 4 and detection signals of the human body position detection means 5 according to Embodiment 1 of the invention. Referring first to FIG. 3( a), a case in which no user 20 is present in the air-conditioned room 4 will be described. When there is no user 20, the signal strength of a vertically oriented output signal 21, which is a signal in the vertical direction (height direction) of the air-conditioned room, remains at zero (level zero) as shown with a vertically oriented output signal 21 a. Further, as for a horizontally oriented output signal 22 in the horizontal direction of the air-conditioned room 4, the signal strength remains at zero, as shown with a horizontally oriented output signal 22 a.
Referring next to FIG. 3( b), a case in which users 20 are present in the air-conditioned room 4 will be described. As illustrated in FIG. 3( b), there are three users, namely, user 20 b, user 20 c, and user 20 d, in the air-conditioned room 4, for example. At this time, a vertically oriented output signal 21 b has three high-signal-level portions where the signal strengths are strong, each corresponding to the height of the users 20 b, 20 c, and 20 d, respectively. Further, a horizontally oriented output signal 22 b also has three portions where the signal levels are high, each corresponding to the positions of the users 20 b, 20 c, and 20 d, respectively. Note that either one of the vertically oriented output signal 21 and the horizontally oriented output signal 22 may detect the user 20. In Embodiment 1, the human body position detection means 5 is provided in the ceiling of the air-conditioned room 4. The human body position detection means 5 transmits the horizontally oriented output signal 22 b to the controller 11.
FIG. 4 is a diagram illustrating a flowchart of a procedure that is performed by the target-room-temperature determination means 12 according to Embodiment 1 of the invention. Referring to FIG. 4, the process of the target-room-temperature determination means 12 will be described. Here, the target-room-temperature determination means 12 presets and stores threshold values that are needed to perform the determination and the like as initial values. For example, the level of occupant number in the air-conditioned room 4 is set. Here, the level of occupant number is set to three levels, namely, low, intermediate, and high. Further, as boundary values of the total area of the heat source object, area 1 and area 2 each serving as a predetermined area value is set. Here, the total heat-source-object area is determined on the basis of the summation of the high-signal-level portions of the horizontally oriented output signal 22 b illustrated in FIG. 3.
Further, in Embodiment 1, the target room temperature is set to a target room temperature for large occupant number when the level of occupant number is high or when the level of occupant number has increased from the preceding determination. Furthermore, the target room temperature is set to a target room temperature for small occupant number when the level of occupant number is low, intermediate, or zero, as well as when the level of occupant number has decreased or has not changed.
First, in step 1, the temperature distribution of the entire air-conditioned room 4 is determined on the basis of the signal transmitted from the human body position detection means 5. Further, in step 2, the total area (total heat-source-object area) of the heat source object (user 20) is calculated on the basis of the temperature distribution.
Next, in step 3, the level of occupant number is determined by comparing the total heat-source-object area and the aforementioned boundary values. For example,

- when total heat-source-object area=0, then the level of occupant number is determined to be zero;
- when 0<total heat-source-object area<area 1, then the level of occupant number is determined to be low;
- when area 1≦total heat-source-object area<area 2, then the level of occupant number is determined to be intermediate; and
- when 2≦total heat-source-object area, then the level of occupant number is determined to be high.

In step 4, it is determined whether the level of occupant number is high on the basis of the determination result. When it is determined to be high, step 6 is processed. When it is determined to be not high (the level of occupant number is zero, low, or intermediate), step 5 is processed. Further, in step 5, it is determined whether the level of occupant number has increased from the preceding determination (scan). When it is determined that the level of occupant number has increased, step 6 is processed. When it is determined that the level of occupant number has not increased (decrease in level or no change), step 7 is processed. Here, increase in the level of occupant number refers to such a case where the preceding level of occupant number that had been determined to be zero is determined to be low, intermediate, or high, for example. Further, there is a case where the preceding level of occupant number that had been determined to be low is determined to be intermediate or high. Furthermore, there is a case where the preceding level of occupant number that had been determined to be intermediate is determined to be high.
After the target room temperature for large occupant number, which has been set when the level of occupant number is high or when the level of occupant number has increased, is determined as the target room temperature in step 6, the process returns to step 1. On the other hand, after the target room temperature for small occupant number—having been set when the level of occupant number is low, intermediate, or zero, or when the level of occupant number has decreased or has not changed—is determined as the target room temperature in step 7, the process returns to step 1. The target-room-temperature determination means 12 determines the target room temperature in the air-conditioned room 4 by performing the above process.
Here, the cooling capacity of the outside air that is introduced into the air-conditioned room 4 by the outside air introduction means 6 can be expressed by the following equation (1). As in equation (1), the cooling capacity can be expressed as a function F1 that is a value obtained by multiplying the air volume to the temperature difference between the target room temperature and the outside air temperature. It can be understood from equation (1) that when the temperature difference between the target room temperature and the outside air temperature is small, larger air volume is required to obtain the same cooling capacity.
Cooling capacity=F1(air volume×(target room temperature−outside air temperature)) (1)
Further, power consumption of the outside air introduction means 6 can be expressed by the following equation (2). As in equation (2), the power consumption of the outside air introduction means 6 can be expressed as a function F2 of the air volume. Accordingly, it can be understood that power consumption increases when air volume is increased.
Power consumption of the fan=F2 (air volume) (2)
FIG. 5 is a diagram illustrating power consumed when the outside air introduction means 6 is driven and when the air-conditioning apparatus is operated. Referring to FIG. 5, the axis of ordinates represents the power consumption, and the axis of abscissas represents the air volume of the outside air introduction means 6. Line 31, representing the power consumption of the outside air introduction means 6 while in operation, shows that the power consumption increases when the air volume of the outside air introduction means 6 increases. On the other hand, Line 32 represents the power consumption of the air-conditioning apparatus (refrigerant circuit) while in operation. The power consumption is mainly that of the driven compressor 101 although it including the power consumption of the driven outdoor side fan 104. As shown in FIG. 5, the power consumption of the air-conditioning apparatus while in operation is substantially constant irrespective of the air volume of the outside air introduction means 6. Further, FIG. 5 shows that the power consumption is lower when the outside air introduction means 6 is operated in the region on the left side of the intersection point between line 31 and line 32 and the power consumption is higher when the outside air introduction means 6 is operated in the region on the right side of the intersection point.
FIG. 6 is a diagram related to the process of the cooling-operation-method determination means 13 according to Embodiment 1 of the invention and is a diagram illustrating the relationship between the cooling operation, when the level of the occupant number is high or when the level has been increased, and the outside air temperature. Here, as an example, the target room temperature determined by the target-room-temperature determination means 12 is set to the target room temperature for large occupant number (22° C.). Further, each of T1, T2, T3, T4, and T5 represents a temperature range of the outside air temperature. Here, T1 is the lowest temperature range. The temperature range becomes higher in the order of T2, T3, and T4, and T5 is the highest temperature range. Here, the temperature within the temperature range T4 is lower than the target room temperature, and the temperature within the temperature range T5 is higher than the target room temperature.
For example, when outside air with a temperature within the lowest temperature range T1 is introduced into the air-conditioned room 4, there is a possibility of dew condensation caused by increase in the relative humidity of air in the area where the air in the air-conditioned room 4 is cooled by mixing of the air in the air-conditioned room and the outside air. Accordingly, there is a possibility of dew condensation water that has occurred near the air outlet of the outside air introduction duct 7 flowing into the air-conditioned room 4; hence, outside air cooling operation cannot be performed. For example, in a case where the temperature in the air-conditioned room 4 is higher than the target room temperature due to heat emitted from heat sources such as OA equipment and the like, even if the outside air temperature is low, a cooling operation with the air-conditioning apparatus is performed.
Further, when the temperature of outside air is within the temperature range T2, which is a temperature that is in the low temperature region but has no risk of dew condensation, cooling effect can be obtained by introducing outside air with a small volume, that is, with a small air volume (introduction volume of outside air), into the air-conditioned room 4. Further, when the temperature of outside air is within the temperature range T3, which is a temperature that is a little higher than that of the temperature range T2, the temperature difference between the target room temperature is smaller compared to that of the outside air in the temperature range T2. Accordingly, based on the aforementioned equation (1), a cooling effect can be obtained by introducing outside air with an intermediate air volume, which has more air volume than the small air volume, into the air-conditioned room 4.
Furthermore, when the temperature of outside air is within the temperature range T4, which is a temperature that is a little higher than that of the temperature range T3, the temperature difference between the target room temperature is smaller still compared to that of the outside air in the temperature range T3. The air volume may be further increased to maintain the cooling capacity; however, as shown in FIG. 5, if the power consumed in the operation of the outside air introduction means 6 exceeds the power consumed by the operation of the air-conditioning apparatus, then the cooling operation with the air-conditioning apparatus will be more energy saving. Accordingly, the compressor 101 is driven and cooling operation is performed with the air-conditioning apparatus when the outside air temperature is within the temperature range T4. When the outside air temperature is within the highest temperature range T5, it will not be possible to perform cooling that introduces outside air since the outside air will heat the air in the air-conditioned room 4. Accordingly, the compressor 101 is driven and a cooling operation with the air-conditioning apparatus is performed.
FIG. 7 is a diagram related to the process of the cooling-operation-method determination means 13 according to Embodiment 1 of the invention and is a diagram illustrating the relationship between the cooling operation—when the level of the occupant number is low, intermediate, or zero, or when the level has been decreased or there has been no change—and the outside air temperature. Here, as an example, the target room temperature determined by the target-room-temperature determination means 12 is set to the target room temperature for small occupant number (25° C.). The relationships between T1 to T5 are the same as FIG. 6.
Since the target room temperature is set high, the cooling capacity can be small. Accordingly, as regards the outside air with a temperature in the temperature ranges T2, T3, and T4, for example, if the temperature difference between the target room temperature and the outside air temperature is the same, from the aforementioned equation (1), the air volume of the fan of the outside air introduction means can be small. For example, in comparison with FIG. 6, when the outside air temperature is a temperature in the temperature range T2, the temperature difference becomes larger than that of FIG. 6, and a cooling effect can be obtained by introducing outside air with a minute air volume into the air-conditioned room 4 rather than a small air volume. Further, also in the case in which the outside air temperature is a temperature in the temperature range T3, since the temperature difference is large, a cooling effect can be obtained by introducing outside air with a small air volume into the air-conditioned room 4 rather than an intermediate air volume. Furthermore, when the outside air temperature is a temperature in the temperature range T4, operation of the air-conditioning apparatus is performed in FIG. 6; however, in FIG. 7, outside air cooling operation can be performed since the operation of the outside air introduction means 6 consumes smaller power than the driving of the compressor 101 and the operation of the air-conditioning apparatus.
As above, according to the air conditioning system of Embodiment 1, since the target-room-temperature determination means 12 determines the target room temperature on the basis of the number of users in the air-conditioned room 4 and the variation of the number thereof, and since the cooling-operation-method determination means 13 determines whether to operate the outdoor unit 1 and the indoor unit 3 or to operate the outside air introduction means 6 on the basis of the target room temperature and the outside air temperature, an energy saving operation using the outside air can be performed while maintaining the temperature to a temperature corresponding to the state of the user(s) 20 in the air-conditioned room 4.

Embodiment 2

In the above-mentioned Embodiment 1, the target-room-temperature determination means 12 determines the target room temperature from the two, the target room temperature for large occupant number and the target room temperature for small occupant number; however, the invention is not limited to the above. For example, the target room temperature may be determined from among three or more set target room temperatures, on the basis of the signal of the human body position detection means 5.

Embodiment 3

FIG. 8 is a schematic diagram illustrating an air-conditioning system according to Embodiment 3 of the invention. Referring to FIG. 8, components and the like attached with like reference numerals serves similar roles as that in Embodiment 1. As illustrated in FIG. 8, the cooling-operation-method determination means 13 includes power consumption determination means 16. The power consumption determination means 16 determines the power consumption of the compressor 101 on the basis of the refrigerant discharge pressure and the discharge temperature of the compressor 101, the rotation speed of the compressor 101, and the like. Further, the power consumption determination means 16 determines the power consumption of the outside air introduction means 6. Thus, the power consumption determination means 16 has tabular data, for example, that shows the relationship between the power consumption and the discharge pressure of the refrigerant, the discharge temperature of the refrigerant, the rotation speed of the compressor 101, and the like. Similarly, the power consumption determination means 16 has tabular data, for example, that shows the relationship between the power consumption and the air volume, the rotation speed, and the like of the outside air introduction means 6.
FIG. 9 is a diagram illustrating a flowchart of a procedure that is performed by the cooling-operation-method determination means 13 according to Embodiment 3 of the invention. The processing operation of the cooling-operation-method determination means 13 provided with the power consumption determination means 16 will be described with reference to FIG. 9.
In step 20, it is determined whether the compressor 101 is driven (whether the air-conditioning apparatus is in operation). When it is determined that the compressor 101 is being driven, the process proceeds to step 21. When it is determined that the compressor 101 is not being driven, the process proceeds to step 26. In step 21, the current refrigerant discharge pressure and the current refrigerant discharge temperature of the compressor 101 and the current rotation speed of the compressor 101 is measured. For the measurement, pressure detection means, temperature detection means, and the like are disposed in the discharge side pipe or the like. Further, in step 22, the power consumption determination means 16 determines the current power consumption of the air-conditioning apparatus (mainly the compressor 101) on the basis of the aforementioned data. In this example, the power consumed by the air-conditioning apparatus is determined on the basis of both data associated with the compressor 101 which consumes majority of the power and a fixed value or values added for the other components; however, its determination may be performed by including the power consumption obtained by measuring or the like the power consumption of the other components, such as the outdoor side fan 104.
In step 23, the air volume and the rotation speed of the outside air introduction means 6, which are required in order to obtain the cooling capacity during the outside air cooling operation, are calculated and determined on the basis of the temperature difference between the current outside air temperature and the target room temperature. Further, in step 24, the power consumed by the operation of the outside air introduction means 6 is estimated and determined on the basis of the above-mentioned equation (2), for example.
In step 25, the calculated power consumption of the compressor 101 and the estimated power consumption of the operation of the outside air introduction means 6 are compared. Further, when it is determined that the power consumption of the compressor 101 is larger than the power consumed by the operation of the outside air introduction means 6, the process proceeds to step 26. Furthermore, when it is determined that the power consumption of the operation of the air-conditioning apparatus is not larger than the power consumed by the operation of the outside air introduction means 6 (the power consumption of the air-conditioning apparatus is equivalent to or smaller than the power consumed by the operation of the outside air induction means 6), the process proceeds to step 30. In step 26, outside air cooling operation is performed. On the other hand, in step 30, the compressor 101 is driven and the cooling operation with the air-conditioning apparatus is performed, and the process proceeds to step 20.
In step 27, the power consumption determination means 16 calculates and determines the current power consumption of the outside air introduction means 6 on the basis of the current rotation speed of the outside air introduction means 6 and the relationship between the current rotation speed of the outside air introduction means 6 and the power consumption. Further, in step 28, the power consumption of the compressor 101 is estimated and determined on the basis of the current room temperature, the target room temperature, and the current outside air temperature and on the basis of the data of the room temperature, the target room temperature, the outside temperature, the pressure, the temperature, the rotation speed, and the power consumption of the compressor 101. In step 29, it is determined whether the power consumption of the outside air introduction means 6 is equivalent to or larger than the power consumption of the air-conditioning apparatus. When it is determined that the power consumption of the outside air introduction means 6 is not equivalent to or larger than the power consumption of the air-conditioning apparatus (the power consumption of the air-conditioning apparatus is larger), the process proceeds to step 26 and outside air cooling operation is performed. On the other hand, when it is determined that the power consumption of the outside air introduction means 6 is equivalent to or larger than the power consumption of the air-conditioning apparatus, the process proceeds to step 30. Further, in step 30, the cooling operation with the air-conditioning apparatus is performed, and the process proceeds to step 20.
As above, according to the air conditioning system of Embodiment 3, the power consumption determination means 16 determines the power consumption of the outside air introduction means 6 and the power consumption of the air-conditioning apparatus by measurement and estimation, directly compares each power consumption with each other, and determines whether the outside air introduction means 6 or the air-conditioning apparatus (compressor 101) is to be operated; hence, determination of energy saving operations with higher precision can be made.

Embodiment 4

In the above-mentioned Embodiments including Embodiment 1, the target room temperature is set such that the target room temperature for small occupant number is higher than the target room temperature for large occupant number; however, the invention is not limited to the above setting and any target room temperature may be set. Further, conditions such as a schedule may be added.
For example, in an office and the like, in the morning and evening when there is heavy traffic of people entering and exiting the office, even if the number of occupants decreases, the target room temperature may be set so as not to be increased since there is a large amount of activity going on, On the other hand, during the daytime when the office is occupied by office workers working at desks, the target room temperature is set such that the target room temperature for small occupant number is higher than the target room temperature for large occupant number, thus achieving energy saving.
Further, for example, at an event site and the like, the target room temperature is set not to be changed even in the daytime. In addition, typically, since the outside air temperature in the night drops and the air conditioning load decreases, the target room temperature may be set on the basis of the number of occupants and thus achieve energy saving.
Furthermore, in the above-mentioned Embodiments including Embodiment 1, the power consumption of each of the compressor 101 and the outside air introduction means 6 is calculated on the basis of preset data; however, a watt-hour meter may be provided measuring each power consumption, for example.
Additionally, in the above-mentioned Embodiments including Embodiment 1, criteria for the target room temperature determination were temperatures related to the detection of the room temperature detection means 9 and the outside air temperature detection means 10; however, the invention is not limited to the above criteria. For example, humidity detection means may be provided inside/outside the air-conditioned room 4 and the enthalpy inside/outside the air-conditioned room 4 may be calculated as data for determining the target room temperature.
Furthermore, in the above-mentioned Embodiments including Embodiment 1, the target room temperature is determined on the basis of the signal from the human body position detection means 5 and in correspondence with the state of the user(s) 20 in the air-conditioned room 4. However, clocking means may be further provided that provides delay time such that the target room temperature is reduced and high cooling is set for a set time period when it is once determined that the user 20 has increased.

REFERENCE SIGNS LIST

1 outdoor unit; 2 refrigerant pipe; 3 indoor unit; 4 air-conditioned room; 5 human body position detection means; 6 outside air introduction means; 7 outside air introduction duct; 8, 8 a, 8 b, 8 c, 8 d, 8 e signal line; 9 room temperature detection means; 10 outside air temperature detection means; 11 controller; 12 target-room-temperature determination means; 13 cooling-operation-method determination means; 16 power consumption determination means; 20, 20 a, 20 b, 20 c, 20 d user; 21, 21 a, 21 b vertically oriented output signal; 22, 22 a, 22 b horizontally oriented output signal; 31 line representing power consumption when outside air introduction means 6 is driven; 32 line representing power consumption when compressor 101 is driven; 101 compressor; 102 four-way valve; 103 outdoor side heat exchanger; 104 outdoor side fan; 301 indoor side heat exchanger; 302 indoor side expansion device; 303 indoor side fan; 300 indoor unit.

Claims

What is claimed is:

1. An air conditioning system, comprising:

an air-conditioning apparatus performing air conditioning of an air-conditioned space by using a refrigerant discharged by a compressor;

a fan supplying air outside the air-conditioned space into the air-conditioned space;

an outside air temperature sensor detecting a temperature outside the air-conditioned space;

a heat source sensor detecting a heat source object in the air-conditioned space;

target-room-temperature determination means determining a target room temperature that is a temperature target of the air-conditioned space by determining a user number and a variation of the user number in the air-conditioned space based on a detection of the heat source sensor; and

cooling-operation-method determination means determining whether to operate the air-conditioning apparatus or to drive the fan based on the target room temperature and the temperature outside the air-conditioned space.

2. The air conditioning system of claim 1, wherein the target-room-temperature determination means determines the target room temperature from among three or more target room temperatures that have been preset based on the user number and the variation of the user number.

3. The air-conditioning system of claim 1, further comprising power consumption determination means determining a power consumption of the air-conditioning apparatus and a power consumption of the fan, wherein

the cooling-operation-method determination means determines whether to operate the air-conditioning apparatus or to operate the fan based on comparison of the power consumption of the air-conditioning apparatus and the power consumption of the fan.

4. The air conditioning system of claim 3, further comprising

an indoor air temperature sensor detecting a temperature inside the air-conditioned space, wherein

the power consumption determination means determines, among the air-conditioning apparatus and the fan, the power consumption of the apparatus and/or the fan in operation by means of measurement, and

the power consumption determination means estimates and determines, among the air-conditioning apparatus and the fan, the power consumption of the apparatus and/or the fan not in operation based on the target room temperature, the temperature outside the air-conditioned space, and the temperature inside the air-conditioned space.