AIR CONDITIONING SYSTEM
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.
Latest Mitsubishi Electric Corporation Patents:
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 LiteraturePatent Literature 1: Japanese Unexamined Patent Application Publication No. 11-006644 (
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 ProblemAn 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 InventionAccording 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.
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 1The 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 8a is a line for transmitting a signal related to a detection of the outside air temperature detection means 10. A signal line 8b is a line for communicating between the indoor unit 3 and the controller 11. A signal line 8c is a line for transmitting a signal related to a detection of the room temperature detection means 9. A signal line 8d is a line for transmitting a signal related to a detection of the human body position detection means 5. A signal line 8e 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.
Referring next to
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)
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
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
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 2In 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 3In 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 4In 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 LIST1 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, 8a, 8b, 8c, 8d, 8e 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, 20a, 20b, 20c, 20d user; 21, 21a, 21b vertically oriented output signal; 22, 22a, 22b 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
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.
Type: Application
Filed: Sep 13, 2012
Publication Date: Mar 13, 2014
Applicant: Mitsubishi Electric Corporation (Chiyoda-ku)
Inventor: Hirotaka MASUI (Cypress, CA)
Application Number: 13/614,305
International Classification: F25B 49/02 (20060101); F25B 1/00 (20060101); F25D 17/06 (20060101);