Air conditioning system

Abstract

The air conditioning system improves the comfort level of the target space being air-conditioned. [Solution] The controller (60) of the air conditioning system (10) performs a first control operation when the load index is lower than a reference value, and a second control operation when the load index is higher than a reference value. The load index correlates with the air conditioning load of the target space (70). The first control operation is to maintain the discharge flow rate at a first flow rate and adjust the discharge temperature so that the temperature of the target space (70) reaches a set temperature. The second control operation is to maintain the discharge temperature at a first temperature and adjust the discharge flow rate so that the temperature of the target space (70) reaches a set temperature.

Description

Technical Field

[0001] The present disclosure relates to an air conditioning system.

Background Art

[0002] An air conditioning system that forms a temperature stratification in a target space is known. The displacement ventilation system disclosed in Patent Document 1 is one type of this air conditioning system.

[0003] The above-described air conditioning system supplies cooled air to the lower part of the target space. As a result, in the target space, an air layer with a relatively low temperature is formed in the lower part of the target space where people are present, and an air layer with a relatively high temperature is formed in the upper part of the target space where people are not present. The air conditioning system sucks air from the upper part of the target space and discharges part or all of the sucked air outdoors.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Generally, an air conditioning system that forms a temperature stratification keeps the flow rate of the air supplied to the target space constant and controls the temperature of the air supplied to the target space according to the cooling load. Therefore, in a situation where the cooling load is high, the temperature of the air blown out by the air conditioning system into the target space becomes too low, and the temperature difference between the lower part and the upper part of the target space becomes large, which may cause discomfort to people in the target space.

[0006] An object of the present disclosure is to improve the comfort of a target space air-conditioned by an air conditioning system that forms a temperature stratification.

Means for Solving the Problems

[0007] A first aspect of the present disclosure is an air conditioning system (10) comprising a processing unit (20) that draws in air and adjusts its temperature, the processing unit (20) blows the temperature-adjusted air into a target space (70) to form a temperature stratification in the target space (70), the air conditioning system (10) comprising a controller (60) that performs a first control operation when a load index correlated with the air conditioning load of the target space (70) is lower than a reference value, and performs a second control operation when the load index is higher than the reference value, the air conditioning system (10 The flow rate of air that the air conditioner (10) blows into the target space (70) is the discharge flow rate, the temperature of the air that the air conditioner (10) blows into the target space (70) is the discharge temperature, the first control operation is an operation to maintain the discharge flow rate at a first flow rate and adjust the discharge temperature so that the temperature of the target space (70) becomes the set temperature, and the second control operation is an operation to maintain the discharge temperature at a first temperature and adjust the discharge flow rate so that the temperature of the target space (70) becomes the set temperature.

[0008] A second aspect of the present disclosure is an air conditioning system (10) comprising a processing unit (20) that draws in air and adjusts its temperature, the processing unit (20) blows the temperature-adjusted air into a target space (70) and forms a temperature stratification in the target space (70), the air conditioning system (10) comprising a controller (60) that performs a first control operation when a load index correlated with the air conditioning load of the target space (70) is lower than a reference value, and performs a second control operation when the load index is higher than the reference value, and the air conditioning system (10) is the target The flow rate of air blown into the space (70) is the discharge flow rate, the temperature of the air blown into the target space (70) by the air conditioning system (10) is the discharge temperature, the first control operation is an operation to maintain the discharge flow rate at a first flow rate and adjust the discharge temperature so that the temperature of the target space (70) becomes the set temperature, and the second control operation is an operation to maintain the discharge flow rate at a second flow rate which is greater than the first flow rate and adjust the discharge temperature so that the temperature of the target space (70) becomes the set temperature.

[0009] In both the first and second embodiments, the controller (60) performs a first control operation when the load index is lower than a reference value, and performs a second control operation when the load index is lower than a reference value. Therefore, the comfort level of the target space (70) is maintained both when the air conditioning load of the target space (70) is relatively low and relatively high.

[0010] A third aspect of the present disclosure, in the first or second aspect described above, comprises a blowing unit (32) that supplies temperature-controlled air from the processing unit (20) to the lower part of the target space (70), and a suction unit (31) that draws in air from the upper part of the target space (70).

[0011] In a third embodiment, the discharge unit (32) supplies temperature-controlled air from the processing unit (20) to the lower part of the target space (70). In the target space (70) where temperature stratification is formed, the temperature at the top of the target space (70) is higher than the temperature at the bottom of the target space (70). The intake unit (31) draws in relatively high-temperature air from the top of the target space (70).

[0012] A fourth aspect of the present disclosure is, in the third aspect described above, the blowing unit (32) is installed above the target space (70) and supplies the temperature-controlled air from the processing unit (20) to the lower part of the target space (70) by blowing it toward the floor of the target space (70).

[0013] In the fourth embodiment, a blowing unit (32) installed at the top of the target space (70) blows air toward the floor of the target space (70). As a result, air whose temperature has been controlled by the processing unit (20) is supplied to the lower part of the target space (70).

[0014] A fifth aspect of this disclosure is that, in any one of the first to third aspects described above, the difference between the temperature of the target space and the outlet temperature is used as the load index.

[0015] In the fifth embodiment, the controller (60) uses the difference between the "temperature of the target space (70)" and the "discharge temperature" as a load indicator.

[0016] In the sixth aspect of the present disclosure, in the third or fourth aspect described above, the difference between the temperature of the air sucked by the suction unit (31) from the target space (70) and the blowing temperature is used as the load index.

[0017] In the sixth aspect, the controller (60) uses the difference between "the temperature of the air sucked by the suction unit (31) from the target space (70)" and "the blowing temperature" as the load index.

Brief Description of the Drawings

[0018] [Figure 1] FIG. 1 is a diagram showing a schematic configuration of an air conditioning system according to Embodiment 1. [Figure 2] FIG. 2 is a diagram showing a first control operation and a second control operation performed by the controller according to Embodiment 1. [Figure 3] FIG. 3 is a flowchart showing a control operation performed by the controller according to Embodiment 1 when the processing unit is performing a cooling operation. [Figure 4] FIG. 4 is a flowchart showing a control operation performed by the controller according to Embodiment 1 when the processing unit is performing a heating operation. [Figure 5] FIG. 5 is a diagram showing a first control operation and a second control operation performed by the controller according to Embodiment 2. [Figure 6] FIG. 6 is a flowchart showing a control operation performed by the controller according to Embodiment 2 when the processing unit is performing a cooling operation. [Figure 7] FIG. 7 is a flowchart showing a control operation performed by the controller according to Embodiment 2 when the processing unit is performing a heating operation. [Figure 8] FIG. 8 is a diagram showing a schematic configuration of an air conditioning system according to a first modification of another embodiment. [Figure 9] FIG. 9 is a diagram showing a schematic configuration of an air conditioning system according to a second modification of another embodiment.

Modes for Carrying Out the Invention

[0019] "Embodiment 1" Embodiment 1 will be described. This embodiment is an air conditioning system (10) that performs air conditioning in a target space.

[0020] As shown in FIG. 1, the air conditioning system (10) includes a processing unit (20), a suction unit (31), a blowing unit (32), a damper unit (33), and a controller (60). The air conditioning system (10) also includes a suction duct (41), a blowing duct (42), an exhaust duct (43), and an outside air duct (44).

[0021] Note that the number of processing units (20) and suction units (31) shown in FIG. 1 is merely an example. The air conditioning system (10) may include a plurality of suction units (31) or a plurality of blowing units (32). Also, the installation positions of the suction unit (31) and the blowing unit (32) in the target space (70) are not limited to the positions shown in FIG. 1. The number of suction units (31) and blowing units (32) included in the air conditioning system (10) and the installation positions of the suction unit (31) and the blowing unit (32) in the target space (70) are appropriately determined according to the size of the target space (70), the shape of the target space (70), the use of the target space (70), the positions of the articles (such as furniture) installed in the target space (70), and the like.

[0022] 〈Processing Unit〉 The processing unit (20) includes an air heat exchanger (21) and a blower (22). The air heat exchanger (21) is connected to a chiller device (not shown) via a water pipe (25). Heat medium water circulates between the air heat exchanger (21) and the chiller device. The air heat exchanger (21) exchanges heat between the heat medium water cooled or heated in the chiller device and the air. The blower (22) sucks in and blows out the air that has passed through the air heat exchanger (21). A flow rate control valve (26) is provided in the water pipe (25). When the opening degree of the flow rate control valve (26) is changed, the flow rate of the heat medium water flowing through the air heat exchanger (21) changes.

[0023] The processing unit (20) adjusts the temperature of the inhaled air. Specifically, the processing unit (20) selectively performs cooling and heating operations. The cooling operation is the operation of cooling the inhaled air in the air heat exchanger (21). The heating operation is the operation of heating the inhaled air in the air heat exchanger (21).

[0024] <Suction Unit> The suction unit (31) is installed on the ceiling of the target space (70). The suction unit (31) draws in air from an intake port facing the target space (70). The suction unit (31) also draws in air from the upper region (71) of the target space (70). The upper region (71) of the target space (70) will be described later.

[0025] <Intake duct, intake temperature sensor> The suction duct (41) is a duct that connects the processing unit (20) and the suction unit (31). One end of the suction duct (41) is connected to the suction unit (31). The other end of the suction duct (41) is connected to the air inlet of the processing unit (20).

[0026] An intake temperature sensor (51) is provided in the intake duct (41). The intake temperature sensor (51) measures the temperature of the air that is drawn into the intake unit (31) and flows through the intake duct (41). The value measured by the intake temperature sensor (51) is substantially equal to the air temperature in the upper region (71) of the target space (70).

[0027] <Exhaust duct, outside air duct> One end of the exhaust duct (43) is connected to the intake duct (41). The other end is connected to the outdoor space. One end of the outdoor air duct (44) is connected to the outdoor space, and the other end is connected to the air inlet of the processing unit (20).

[0028] <Air outlet unit> The air outlet unit (32) is installed on the ceiling of the target space (70). The air outlet unit (32) blows air from an outlet facing the target space (70) toward the floor of the target space (70). The air outlet unit (32) is installed on the ceiling of the target space (70).

[0029] <Air outlet duct, air outlet temperature sensor> The discharge duct (42) is a duct that connects the processing unit (20) and the discharge unit (32). One end of the discharge duct (42) is connected to the air outlet of the processing unit (20). The other end of the discharge duct (42) is connected to the discharge unit (32).

[0030] A discharge temperature sensor (52) is provided in the discharge duct (42). The discharge temperature sensor (52) measures the temperature of the air that is discharged from the processing unit (20) and flows through the discharge duct (42).

[0031] <Damper Unit> The damper unit (33) is installed in the discharge duct (42). The damper unit (33) is a variable air volume control device (VAV). Although not shown in the diagram, the damper unit (33) includes a wind speed sensor and a damper controller. The wind speed sensor measures the flow velocity of the air passing through the damper unit (33). The damper controller uses the wind speed sensor's measurement to control the opening of the damper unit (33) so that the "flow rate of air passing through the damper unit (33)" becomes the "set flow rate received from the controller (60)".

[0032] <Indoor temperature sensor> The air conditioning system (10) is equipped with an indoor temperature sensor (53). The indoor temperature sensor (53) is installed in the lower layer (72) of the target space (70). The indoor temperature sensor (53) measures the temperature in the lower layer (72) of the target space (70). The lower layer (72) of the target space (70) will be described later.

[0033] <Controller> The controller (60) comprises a microcomputer (61) and a memory device (62). The controller (60) receives input from the intake temperature sensor (51), the discharge temperature sensor (52), and the room temperature sensor (53). The microcomputer (61) of the controller (60) adjusts the opening degree of the flow control valve (26) and the set flow rate of the damper unit (33) by executing a program recorded in the memory device (62).

[0034] -Operation of the air conditioning system- The air conditioning system (10) cools the target space (70). The air conditioning system (10) also forms a temperature stratification in the target space (70).

[0035] When the blower (22) of the processing unit (20) is activated, air from the upper region (71) of the target space (70) is drawn into the intake unit (31). A portion of the air drawn into the intake unit (31) is discharged outdoors through the exhaust duct (43), and the remainder flows into the processing unit (20). In addition, outside air flows into the processing unit (20) through the outside air duct (44).

[0036] Air flowing into the processing unit (20) exchanges heat with the heat transfer fluid as it passes through the air heat exchanger (21). The air whose temperature has been adjusted in the air heat exchanger (21) is blown out of the processing unit (20) and flows through the discharge duct (42) into the discharge unit (32). The discharge unit (32) blows out the incoming air (air whose temperature has been adjusted in the processing unit (20)) toward the floor of the target space (70). The air blown out from the discharge unit (32) reaches near the floor of the target space (70) and flows and diffuses along the floor of the target space (70).

[0037] The air conditioning system (10) cools the target space (70) by supplying air that is cooler than the ambient temperature of the target space (70) to the target space (70). Therefore, the processing unit (20) adjusts the temperature of the intake air so that the temperature of the air that has passed through the air heat exchanger (21) is lower than the ambient temperature of the target space (70).

[0038] Meanwhile, the processing unit (20) receives air drawn in by the suction unit (31) and outside air that has passed through the outside air duct (44). Therefore, the temperature of the air flowing into the processing unit (20) changes according to the temperature of the outside air.

[0039] For example, in the summer when the outside temperature is high, the temperature of the air flowing into the processing unit (20) is usually higher than the ambient temperature of the target space (70). In this case, the processing unit (20) performs a cooling operation. During the cooling operation, the processing unit (20) exchanges heat with the air using the heat transfer fluid cooled by the chiller device in the air heat exchanger (21). The processing unit (20) then blows the air cooled in the air heat exchanger (21) towards the blowing unit (32).

[0040] Furthermore, in winter when the outside air temperature is low, the temperature of the air flowing into the processing unit (20) is usually lower than the ambient temperature of the target space (70). In this case, the processing unit (20) performs a heating operation. During the heating operation, the processing unit (20) exchanges heat between the heat transfer water heated by the chiller device and the air in the air heat exchanger (21). The processing unit (20) then blows the air heated in the air heat exchanger (21) towards the blowing unit (32).

[0041] -Temperature stratification of the target space- In the target space (70), air whose temperature has been regulated in the processing unit (20) and blown out from the blowing unit (32) is supplied to the lower part of the target space (70). As described above, the air blown out from the blowing unit (32) reaches near the floor of the target space (70) and flows and diffuses along the floor. As a result, a lower layer region (72) with a relatively lower temperature is formed in the lower part of the target space (70). The lower layer region (72) is the space where people using the target space (70) are located. Therefore, in the target space (70), the temperature of the lower layer region (72) where people are located can be efficiently maintained within a comfortable range.

[0042] In the target space (70), air heated by the heat generated by people and equipment in the lower region (72) moves upward and accumulates in the upper part of the target space (70). As a result, an upper region (71) with a relatively higher temperature is formed in the upper part of the target space (70). The air conditioning system (10) discharges a portion of the air drawn in from the upper region (71) with a relatively higher temperature to the outside, and the remaining air is temperature-controlled in the processing unit (20).

[0043] Furthermore, pollutants such as carbon dioxide and odor-causing substances generated in the lower layer (72) move upward with the rising air and accumulate in the upper layer (71). The air conditioning system (10) discharges a portion of the air drawn in from the upper layer (71), where the concentration of pollutants is relatively high, to the outside. Therefore, pollutants in the target space (70) can be efficiently discharged to the outside of the target space (70).

[0044] The air conditioning system (10) of this embodiment supplies temperature-controlled air to the lower region (72) of the target space (70), while simultaneously drawing in a portion of the air from the upper region (71) of the target space (70) and discharging it outdoors, with the remaining air being temperature-controlled in the processing unit (20). Therefore, by using the air conditioning system (10) of this embodiment, cooling and ventilation of the target space (70) can be performed efficiently.

[0045] -Control operations performed by the controller (overview)- As shown in Figure 2, the controller (60) selectively performs a first control operation and a second control operation. The controller (60) performs the first control operation when the load index L is less than or equal to the reference value Lr, and performs the second control operation when the load index L is greater than the reference value Lr. Alternatively, the controller (60) may perform the first control operation when the load index is less than the reference value Lr, and perform the second control operation when the load index is greater than or equal to the reference value Lr. The reference value Lr is, for example, 6°C.

[0046] <Load index> In this embodiment, the load index L is the difference between the "temperature of the target space (70)" and the "discharge temperature". The controller (60) in this embodiment uses the difference between the measured value θim from the indoor temperature sensor (53) and the measured value θsm from the discharge temperature sensor (52) as the load index L (L = θim - θsm).

[0047] The indoor temperature sensor (53) measures the temperature of the lower layer (72) of the target space (70). Therefore, the measured value θim from the indoor temperature sensor (53) is the actual measured value of the "temperature of the target space (70)".

[0048] The "discharge temperature" is the temperature of the air that the air conditioning system (10) blows into the target space (70). The discharge temperature sensor (52) measures the temperature of the air that is blown out from the processing unit (20) and flows through the discharge duct (42). The "temperature of the air flowing through the discharge duct (42)" is substantially equal to the "temperature of the air blown out from the discharge unit (32) into the target space (70)". Therefore, the measured value θsm of the discharge temperature sensor (52) is the actual measured value of the "discharge temperature".

[0049] As the temperature of the target space (70) increases, the cooling load of the target space (70) increases. Therefore, as the cooling load of the target space (70) increases, the difference between the "temperature of the target space (70)" and the "discharge temperature" increases. Thus, the difference between the "temperature of the target space (70)" and the "discharge temperature" correlates with the cooling load of the target space (70). Furthermore, the cooling load is a type of air conditioning load. Accordingly, the difference between the measured value θim from the indoor temperature sensor (53) and the measured value θsm from the discharge temperature sensor (52) (θim-θsm) is a load index L that correlates with the air conditioning load of the target space (70).

[0050] <First control action> As shown in Figure 2, the first control operation is to maintain the discharge flow rate at the first flow rate and adjust the discharge temperature so that the temperature of the target space (70) reaches the set temperature.

[0051] The "discharge flow rate" is the flow rate of air that the air conditioning system (10) blows into the target space (70). In the air conditioning system (10) of this embodiment, the air blown out from the processing unit (20) and flowing through the discharge duct (42) passes through the damper unit (33) before being blown out from the discharge unit (32) into the target space. Therefore, the "discharge flow rate" is substantially equal to the "flow rate of air passing through the damper unit (33)".

[0052] In the first control operation, the controller (60) controls the opening of the flow control valve (26) so that the measured value θim from the indoor temperature sensor (53) becomes the indoor set temperature θi. In the first control operation, the controller (60) controls the opening of the flow control valve (26) so that the discharge temperature decreases as the load index L increases.

[0053] When the processing unit (20) is performing a cooling operation, the controller (60) increases the opening of the flow control valve (26) as the load index L increases. As the opening of the flow control valve (26) increases, the flow rate of the heat transfer fluid (chilled water) flowing through the air heat exchanger (21) increases, and consequently the temperature of the air that has passed through the air heat exchanger (21) decreases. As a result, the discharge temperature decreases as the load index L increases.

[0054] When the processing unit (20) is performing a heating operation, the controller (60) reduces the opening of the flow control valve (26) as the load index L increases. As the opening of the flow control valve (26) decreases, the flow rate of the heat transfer fluid (hot water) flowing through the air heat exchanger (21) decreases, and consequently the temperature of the air that has passed through the air heat exchanger (21) decreases. As a result, the discharge temperature decreases as the load index L increases.

[0055] Furthermore, in the first control operation, the controller (60) maintains the set flow rate transmitted to the damper unit (33) at the first flow rate. As a result, the flow rate of air blown from the discharge unit (32) to the target space (70) (discharge flow rate) is maintained at the first flow rate.

[0056] <Second control operation> As shown in Figure 2, the second control operation is to maintain the discharge temperature at the first temperature and adjust the discharge flow rate so that the temperature of the target space (70) reaches the set temperature.

[0057] In the second control operation, the controller (60) adjusts the set flow rate transmitted to the damper unit (33) so that the measured value θim from the indoor temperature sensor (53) becomes the indoor set temperature θi. The controller (60) increases the set flow rate as the load index L increases. As the set flow rate increases, the flow rate of air passing through the damper unit (33) increases, and as a result, the flow rate of air blown out from the discharge unit (32) to the target space (70) (discharge flow rate) increases.

[0058] Furthermore, in the second control operation, the controller (60) controls the opening degree of the flow control valve (26) so that the discharge temperature is maintained at the first temperature. Specifically, the controller (60) controls the opening degree of the flow control valve (26) so that the measured value θsm of the discharge temperature sensor (52) becomes the first temperature.

[0059] When the processing unit (20) is performing a cooling operation, the controller (60) increases the opening of the flow control valve (26) when the measured value θsm from the discharge temperature sensor (52) is higher than the first temperature, and decreases the opening of the flow control valve (26) when the measured value θsm from the discharge temperature sensor (52) is lower than the first temperature.

[0060] On the other hand, when the processing unit (20) is performing a heating operation, the controller (60) reduces the opening of the flow control valve (26) when the measured value θsm of the discharge temperature sensor (52) is higher than the first temperature, and increases the opening of the flow control valve (26) when the measured value θsm of the discharge temperature sensor (52) is lower than the first temperature.

[0061] -Control operations performed by the controller (details, during cooling operation)- The control operations performed by the controller (60) while the processing unit (20) is performing a cooling operation will be explained with reference to the flowchart in Figure 3. In Figure 3, the processing from step ST11 to step ST15 is the first control operation, and the processing from step ST21 to step ST25 is the second control operation.

[0062] <Step ST11> In step ST11, the controller (60) sets the set flow rate to be transmitted to the damper unit (33) to the first flow rate. The damper unit (33) controls the opening of the damper unit (33) so that the flow rate of air passing through the damper unit (33) becomes the first flow rate. As a result, the flow rate of air blown from the discharge unit (32) into the target space (70) is maintained at the first flow rate. When step ST11 is completed, the controller (60) performs step ST12.

[0063] <Step ST12> In step ST12, the controller (60) obtains the measured value θim from the indoor temperature sensor (53). The controller (60) then determines whether the condition "the measured value θim from the indoor temperature sensor (53) is higher than the set value θi for the indoor temperature (θi < θim)" is met. If this condition is met, the controller (60) proceeds to step ST13. If this condition is not met, the controller (60) proceeds to step ST14.

[0064] <Step ST13> In step ST13, the controller (60) increases the opening of the flow control valve (26) and then waits for a predetermined time (for example, 10 minutes). When the opening of the flow control valve (26) increases, the flow rate of the heat transfer fluid (chilled water) flowing through the air heat exchanger (21) increases, and the temperature of the air blown out by the discharge unit (32) into the target space (70) decreases. When step ST13 is completed, the controller (60) performs the process of step ST15.

[0065] <Step ST14> In step ST14, the controller (60) reduces the opening of the flow control valve (26) and then waits for a predetermined time (for example, 10 minutes). When the opening of the flow control valve (26) is reduced, the flow rate of the heat transfer fluid (chilled water) flowing through the air heat exchanger (21) decreases, and the temperature of the air blown out by the blowing unit (32) into the target space (70) increases. When step ST14 is completed, the controller (60) performs the process of step ST15.

[0066] <Step ST15> In step ST15, the controller (60) determines whether the condition “the load index L is higher than the reference value Lr” is met. As described above, the load index L in this embodiment is the difference between the measured value θim from the indoor temperature sensor (53) and the measured value θsm from the outlet temperature sensor (52) (L = θim - θsm). This condition is met when the cooling load in the target space (70) is relatively high. If this condition is met, the controller (60) performs the process in step ST21. On the other hand, if this condition is not met, the controller (60) performs the process in step ST11 in order to continue the first control operation.

[0067] <Step ST21> In step ST21, the controller (60) obtains the measured value θim from the indoor temperature sensor (53). The controller (60) then determines whether the condition "the measured value θim from the indoor temperature sensor (53) is higher than the set value θi for the indoor temperature (θi < θim)" is met. If this condition is met, the controller (60) proceeds to step ST22. If this condition is not met, the controller (60) proceeds to step ST23.

[0068] <Step ST22> In step ST22, the controller (60) increases the set flow rate transmitted to the damper unit (33) and then waits for a predetermined time (for example, 10 minutes). The damper unit (33) controls its opening so that the flow rate of air passing through it becomes the set flow rate. As a result, the flow rate of air blown from the discharge unit (32) into the target space (70) increases. When step ST22 is completed, the controller (60) performs step ST24.

[0069] <Step ST23> In step ST23, the controller (60) reduces the set flow rate transmitted to the damper unit (33) and then waits for a predetermined time (for example, 10 minutes). The damper unit (33) controls its opening so that the flow rate of air passing through it becomes the set flow rate. As a result, the flow rate of air blown from the discharge unit (32) into the target space (70) decreases. When step ST23 is completed, the controller (60) performs step ST24.

[0070] <Step ST24> When the flow rate of air passing through the damper unit (33) changes, the flow rate of air passing through the air heat exchanger (21) of the processing unit (20) changes accordingly. If the flow rate of the heat transfer fluid flowing through the air heat exchanger (21) is constant, then when the flow rate of air passing through the air heat exchanger (21) changes, the temperature of the air that has passed through the air heat exchanger (21) changes accordingly.

[0071] Therefore, in step ST24, the controller (60) adjusts the opening of the flow control valve (26) so that the measured value θsm of the discharge temperature sensor (52) is maintained at the first temperature. Specifically, the controller (60) increases the opening of the flow control valve (26) if the measured value θsm is higher than the first temperature, decreases the opening of the flow control valve (26) if the measured value θsm is lower than the first temperature, and maintains the opening of the flow control valve (26) if the measured value θsm is at the first temperature. After the processing of step ST24 is completed, the controller (60) performs the processing of step ST25.

[0072] <Step ST25> In step ST25, the controller (60) determines whether the condition “the load index L is less than or equal to (reference value Lr-1.5)” is met. As described above, the load index L in this embodiment is the difference between the measured value θim from the indoor temperature sensor (53) and the measured value θsm from the outlet temperature sensor (52) (L=θim-θsm). This condition is met when the cooling load of the target space (70) is relatively high. Therefore, if this condition is met, the controller (60) performs the process in step ST21 in order to continue the second control operation. On the other hand, if this condition is not met, it can be determined that the cooling load of the target space (70) is relatively low. Therefore, if this condition is not met, the controller (60) performs the process in step ST11 in order to perform the first control operation.

[0073] -Control operations performed by the controller (details, during heating operation)- The control operations performed by the controller (60) when the processing unit (20) is performing a heating operation will be explained with reference to the flowchart in Figure 4.

[0074] As shown in Figure 4, the controller (60) performs the process of step ST13' instead of the process of step ST13 in Figure 3, the process of step ST14' instead of the process of step ST14 in Figure 3, and the process of step ST24' instead of the process of step ST24 in Figure 3. The processes of steps ST13', ST14', and ST24' will be described here.

[0075] <Step ST13'> In step ST13', the controller (60) reduces the opening of the flow control valve (26) and then waits for a predetermined time (for example, 10 minutes). When the opening of the flow control valve (26) is reduced, the flow rate of the heat transfer fluid (hot water) flowing through the air heat exchanger (21) decreases, and the temperature of the air blown out by the discharge unit (32) into the target space (70) decreases. When step ST13' is completed, the controller (60) performs the process of step ST15.

[0076] <Step ST14'> In step ST14', the controller (60) increases the opening of the flow control valve (26) and then waits for a predetermined time (for example, 10 minutes). When the opening of the flow control valve (26) increases, the flow rate of the heat transfer fluid (hot water) flowing through the air heat exchanger (21) increases, and the temperature of the air blown out by the blowing unit (32) into the target space (70) rises. When step ST14' is completed, the controller (60) performs the process of step ST15.

[0077] <Step ST24'> In step ST24', the controller (60) adjusts the opening of the flow control valve (26) so that the measured value θsm from the discharge temperature sensor (52) is maintained at the first temperature. Specifically, if the measured value θsm is higher than the first temperature, the controller (60) reduces the opening of the flow control valve (26); if the measured value θsm is lower than the first temperature, it increases the opening of the flow control valve (26); and if the measured value θsm is at the first temperature, it maintains the opening of the flow control valve (26). After step ST24' is completed, the controller (60) performs the process of step ST25.

[0078] -Features of Embodiment 1 (1)- In the air conditioning system (10) of this embodiment, the controller (60) performs a first control operation when the load index L is lower than the reference value Lr. In the first control operation, the controller (60) maintains the discharge flow rate at a first flow rate and adjusts the discharge temperature so that the temperature of the target space (70) reaches the set temperature.

[0079] When the load index L is lower than the standard value Lr, the cooling load in the target space (70) is relatively small, so the outlet temperature does not become too low and is kept within an appropriate range. Therefore, in the target space (70), the temperature in the lower area (72) where people are located is kept within an appropriate range, and the temperature difference between the upper area (71) and the lower area (72) is kept below a predetermined value. Consequently, the comfort level of the target space (70) is maintained at a high level.

[0080] Furthermore, in the air conditioning system (10) of this embodiment, the controller (60) performs a second control operation when the load index L is higher than the reference value Lr. In the second control operation, the controller (60) maintains the discharge temperature at the first temperature and adjusts the discharge flow rate so that the temperature of the target space (70) reaches the set temperature.

[0081] When the load index L is higher than the standard value Lr, the cooling load in the target space (70) is relatively high, but the outlet temperature is maintained at the first temperature. Therefore, even when the cooling load in the target space (70) is relatively high, the outlet temperature does not become too low. Consequently, even when the cooling load in the target space (70) is relatively high, the temperature in the lower area (72) where people are located is kept within an appropriate range, and the temperature difference between the upper area (71) and the lower area (72) is kept below a predetermined value. As a result, a high level of comfort is maintained in the target space (70).

[0082] Thus, according to the air conditioning system (10) of this embodiment, it is possible to maintain a high level of comfort in the target space (70) both when the cooling load of the target space (70) is relatively low and when it is relatively high.

[0083] -Features of Embodiment 1 (2)- The air conditioning system (10) of this embodiment forms a temperature stratification in the target space (70) by causing the air blown downward by the discharge unit (32) to reach the floor of the target space (70). Therefore, according to the air conditioning system (10) of this embodiment, it is possible to efficiently conditioned the air in the target space (70) by forming a temperature stratification in the target space (70) while avoiding increased complexity of the building structure and increased labor costs when installing the air conditioning system (10) in the building.

[0084] -Features of Embodiment 1 (3)- Here, if the vertical temperature difference in the target space (70) (specifically, the temperature difference between the upper and lower parts of the target space (70)) exceeds a predetermined upper limit, a person in the target space (70) may experience discomfort.

[0085] On the other hand, in the air conditioning system (10) of this embodiment, the difference between the "temperature of the target space (70)" and the "discharge temperature" is used as the load index L that the controller (60) uses to select between the first control operation and the second control operation. This load index L correlates with the vertical temperature difference in the target space (70) (hereinafter referred to as the "vertical temperature difference"). As the vertical temperature difference increases, the load index L also increases.

[0086] In the air conditioning system (10) of this embodiment, the load index L when the vertical temperature difference is at its upper limit can be set to a reference value Lr. Then, by using the reference value Lr set in this way, the controller (60) selects between a first control operation and a second control operation, thereby keeping the vertical temperature difference below the upper limit. As a result, it is possible to prevent people in the target space (70) from experiencing discomfort caused by the vertical temperature difference, and to maintain a high level of comfort in the target space (70).

[0087] Embodiment 2 Embodiment 2 will now be described. The air conditioning system (10) of this embodiment is the same as the air conditioning system (10) of Embodiment 1, but with the damper unit (33) and controller (60) changed. Here, the differences between the air conditioning system (10) of this embodiment and the air conditioning system (10) of Embodiment 1 will be mainly described.

[0088] -Damper Unit- The damper unit (33) in this embodiment is a Constant Air Volume (CAV) control device. Although not shown in the figures, the damper unit (33) includes a wind speed sensor and a damper controller. The wind speed sensor measures the flow velocity of the air passing through the damper unit (33). The damper controller uses the wind speed sensor's measurement to control the opening of the damper unit (33) so that the "flow rate of air passing through the damper unit (33)" becomes a "pre-set flow rate". The "set flow rate" of the damper unit (33) can be changed based on instructions transmitted from the controller (60).

[0089] -Controller- The controller (60) of this embodiment, like the controller (60) of Embodiment 1, includes a microcomputer (61) and a memory device (62). The controller (60) of this embodiment controls the opening degree of the flow control valve (26) and issues instructions to the damper unit (33) to change the set flow rate. As will be described later, the control operations performed by the controller (60) of this embodiment differ from those of the controller (60) of Embodiment 1.

[0090] -Control operations performed by the controller (overview)- As shown in Figure 5, the controller (60) selectively performs a first control operation and a second control operation. Similar to the controller (60) of Embodiment 1, the controller (60) of this embodiment performs a first control operation when the load index L is less than or equal to the reference value Lr, and performs a second control operation when the load index L is greater than the reference value Lr. Alternatively, the controller (60) of this embodiment may perform a first control operation when the load index is less than the reference value Lr, and perform a second control operation when the load index is greater than or equal to the reference value Lr, similar to the controller (60) of Embodiment 1.

[0091] <Load index> The controller (60) of this embodiment, like the controller (60) of Embodiment 1, uses the difference between the measured value θim from the indoor temperature sensor (53) and the measured value θsm from the outlet temperature sensor (52) as the load index L (L = θim - θsm).

[0092] <First control action> As shown in Figure 5, the first control operation is to maintain the discharge flow rate at a first flow rate and adjust the discharge temperature so that the temperature of the target space (70) reaches the set temperature. The first control operation performed by the controller (60) in this embodiment is the same as the first control operation performed by the controller (60) in Embodiment 1. A description of the first control operation performed by the controller (60) in this embodiment will be omitted.

[0093] <Second control operation> As shown in Figure 5, the second control operation is to maintain the discharge flow rate at a second flow rate that is greater than the first flow rate, and to adjust the discharge temperature so that the temperature of the target space (70) reaches the set temperature. The second control operation performed by the controller (60) in this embodiment is different from the second control operation performed by the controller (60) in Embodiment 1.

[0094] In the second control operation, the controller (60) of this embodiment transmits an instruction signal to the damper unit (33) to change the set airflow rate from the first airflow rate to the second airflow rate. Upon receiving this instruction signal, the damper unit (33) increases the set airflow rate from the first airflow rate to the second airflow rate. The damper unit (33) then adjusts the opening of the damper unit (33) so that the airflow rate passing through the damper unit (33) becomes the second airflow rate.

[0095] In the second control operation, the controller (60) controls the opening of the flow control valve (26) so that the measured value θim from the indoor temperature sensor (53) becomes the set value θi for the indoor temperature. In the second control operation, the controller (60) controls the opening of the flow control valve (26) so that the discharge temperature decreases as the load index L increases. This operation is the same as the operation performed by the controller (60) in the first control operation.

[0096] When the processing unit (20) is performing a cooling operation, the controller (60) increases the opening of the flow control valve (26) as the load index L increases. As the opening of the flow control valve (26) increases, the flow rate of the heat transfer fluid (chilled water) flowing through the air heat exchanger (21) increases, and consequently the temperature of the air that has passed through the air heat exchanger (21) decreases. As a result, the discharge temperature decreases as the load index L increases.

[0097] When the processing unit (20) is performing a heating operation, the controller (60) reduces the opening of the flow control valve (26) as the load index L increases. As the opening of the flow control valve (26) decreases, the flow rate of the heat transfer fluid (hot water) flowing through the air heat exchanger (21) decreases, and consequently the temperature of the air that has passed through the air heat exchanger (21) decreases. As a result, the discharge temperature decreases as the load index L increases.

[0098] -Control operations performed by the controller (details, during cooling operation)- The control operations performed by the controller (60) while the processing unit (20) is performing a cooling operation will be explained in detail with reference to the flowchart in Figure 6. In Figure 6, the processes from step ST11 to step ST15 are the first control operations, and the processes from step ST31 to step ST35 are the second control operations.

[0099] As described above, the first control operation performed by the controller (60) of this embodiment is the same as the first control operation performed by the controller (60) of Embodiment 1. Therefore, the processing from step ST11 to step ST15 in Figure 6 is the same as the processing from step ST11 to step ST15 in Figure 3. Thus, the explanation of the processing from step ST11 to step ST15 will be omitted.

[0100] <Step ST31> The condition in step ST15 is met when the cooling load in the target space (70) is relatively high. Therefore, when this condition is met, the controller (60) performs the process in step ST31 in order to start the second control operation.

[0101] In step ST31, the controller (60) sends an instruction signal to the damper unit (33) to change the set airflow rate from the first airflow rate to the second airflow rate. Upon receiving this instruction signal, the damper unit (33) adjusts the opening of the damper unit (33) so that the airflow rate passing through the damper unit (33) becomes the second airflow rate. After the processing of step ST31 is completed, the controller (60) performs the processing of step ST32.

[0102] <Step ST32> In step ST32, the controller (60) obtains the measured value θim from the indoor temperature sensor (53). The controller (60) then determines whether the condition "the measured value θim from the indoor temperature sensor (53) is higher than the set value θi for the indoor temperature (θi < θim)" is met. If this condition is met, the controller (60) proceeds to step ST33. If this condition is not met, the controller (60) proceeds to step ST34.

[0103] <Step ST33> In step ST33, the controller (60) increases the opening of the flow control valve (26) and then waits for a predetermined time (for example, 10 minutes). When the opening of the flow control valve (26) increases, the flow rate of the heat transfer fluid (chilled water) flowing through the air heat exchanger (21) increases, and the temperature of the air blown out by the blowing unit (32) into the target space (70) decreases. When step ST33 is completed, the controller (60) performs the process of step ST35.

[0104] <Step ST34> In step ST34, the controller (60) reduces the opening of the flow control valve (26) and then waits for a predetermined time (for example, 10 minutes). When the opening of the flow control valve (26) is reduced, the flow rate of the heat transfer fluid (chilled water) flowing through the air heat exchanger (21) decreases, and the temperature of the air blown out by the blowing unit (32) into the target space (70) increases. When step ST34 is completed, the controller (60) performs the process of step ST35.

[0105] <Step ST35> In step ST35, the controller (60) determines whether the condition “the load index L is less than or equal to a predetermined judgment criterion value” is met. The judgment criterion value in step ST35 is “(Lr-1.5) × (first flow rate / second flow rate)”. As mentioned above, Lr is the criterion value related to the load index.

[0106] The condition in step ST35 is met when the cooling load of the target space (70) is relatively high. Therefore, if this condition is met, the controller (60) performs the process in step ST31 in order to continue the second control operation. On the other hand, if this condition is not met, it can be determined that the cooling load of the target space (70) is relatively low. Therefore, if this condition is not met, the controller (60) performs the process in step ST11 in order to perform the first control operation.

[0107] -Control operations performed by the controller (details, during heating operation)- The control operations performed by the controller (60) when the processing unit (20) is performing a heating operation will be explained with reference to the flowchart in Figure 7.

[0108] As shown in Figure 7, the controller (60) performs the process of step ST13' instead of the process of step ST13 in Figure 6, the process of step ST14' instead of the process of step ST14 in Figure 6, the process of step ST33' instead of the process of step ST33 in Figure 6, and the process of step ST34' instead of the process of step ST34 in Figure 6. The process of step ST13' in Figure 7 is the same as the process of step ST13' in Figure 4. The process of step ST14' in Figure 7 is the same as the process of step ST14' in Figure 4. The processes of steps ST33' and ST34' will be explained here.

[0109] <Step ST33'> In step ST33', the controller (60) reduces the opening of the flow control valve (26) and then waits for a predetermined time (for example, 10 minutes). When the opening of the flow control valve (26) is reduced, the flow rate of the heat transfer fluid (hot water) flowing through the air heat exchanger (21) decreases, and the temperature of the air blown out by the discharge unit (32) into the target space (70) decreases. When step ST33' is completed, the controller (60) performs the process of step ST35.

[0110] <Step ST34'> In step ST34', the controller (60) increases the opening of the flow control valve (26) and then waits for a predetermined time (for example, 10 minutes). When the opening of the flow control valve (26) increases, the flow rate of the heat transfer fluid (hot water) flowing through the air heat exchanger (21) increases, and the temperature of the air blown out by the blowing unit (32) into the target space (70) rises. When step ST34' is completed, the controller (60) performs the process of step ST35.

[0111] -Features of Embodiment 2- According to the air conditioning system (10) of this embodiment, similar to the air conditioning system (10) of Embodiment 1, it is possible to maintain a high level of comfort in the target space (70) both when the cooling load of the target space (70) is relatively low and when it is relatively high.

[0112] Other embodiments The following modifications may be applied to the air conditioning system (10) of the above embodiment. These modifications may be combined or substituted as appropriate, as long as they do not impair the function of the air conditioning system (10).

[0113] -First variation- As shown in Figure 8, in the air conditioning systems (10) of Embodiments 1 and 2, the intake duct (41) may be omitted, and one end of the exhaust duct (43) may be connected to the intake unit (31).

[0114] In this modified air conditioning system (10), the intake temperature sensor (51) is installed in the exhaust duct (43). The intake temperature sensor (51) measures the temperature of the air that is drawn into the intake unit (31) and flows through the exhaust duct (43). The value measured by the intake temperature sensor (51) is substantially equal to the air temperature in the upper region (71) of the target space (70).

[0115] In this modified air conditioning system (10), only outdoor air flowing through the outdoor air duct (44) flows into the processing unit (20). Similar to the processing units (20) in embodiments 1 and 2, the processing unit (20) adjusts the temperature of the incoming air in the air heat exchanger (21) and blows the temperature-adjusted air into the discharge duct (42).

[0116] -Second variation- As shown in Figure 9, the air conditioning systems (10) of Embodiments 1 and 2 may include an air handling unit (35).

[0117] The air handling unit (35) is installed in the outside air duct (44) and adjusts the temperature of the outside air that flows through the outside air duct (44) and heads toward the processing unit (20).

[0118] The air handling unit (35) comprises an outside air heat exchanger (36) and a blower (37). The outside air heat exchanger (36), like the air heat exchanger (21) of the processing unit (20), is connected to a chiller device (not shown) via piping. Heat transfer water circulates between the outside air heat exchanger (36) and the chiller device. The outside air heat exchanger (36) exchanges heat between the heat transfer water, which has been cooled or heated in the chiller device, and the air. The blower (37) draws in and blows out the air that has passed through the outside air heat exchanger (36).

[0119] In this modified air conditioning system (10), the outside air flowing through the outside air duct (44) is temperature-controlled in the air handling unit (35) before flowing into the processing unit (20). For example, in the summer when the outside air temperature is high, the outside air flowing through the outside air duct (44) is cooled in the outside air heat exchanger (36) before flowing into the processing unit (20). Also, in the winter when the outside air temperature is low, the outside air flowing through the outside air duct (44) is heated in the outside air heat exchanger (36) before flowing into the processing unit (20).

[0120] -Third variation- In the air conditioning systems (10) of Embodiments 1 and 2, the load index L used by the controller (60) in control operation may be the difference between the temperature of the air drawn in by the intake unit (31) from the target space (70) and the discharge temperature. In this modified example, the controller (60) uses the difference between the measured value θem from the intake temperature sensor (51) and the measured value θsm from the discharge temperature sensor (52) as the load index L (L = θem - θsm).

[0121] The temperature of the air drawn in by the suction unit (31) from the target space (70) is substantially equal to the temperature of the air flowing through the suction duct (41). Therefore, the measured value θem of the suction temperature sensor (51) is the actual measured value of the temperature of the air drawn in by the suction unit (31) from the target space (70).

[0122] The measurement value θem from the intake temperature sensor (51) is substantially equal to the temperature of the upper region (71) of the target space (70). As the temperature of the upper region (71) of the target space (70) increases, the cooling load of the target space (70) increases. Therefore, as the cooling load of the target space (70) increases, the difference between the temperature of the air drawn in by the intake unit (31) from the target space (70) and the outlet temperature increases. Thus, the difference between the temperature of the air drawn in by the intake unit (31) from the target space (70) and the outlet temperature correlates with the cooling load of the target space (70). Furthermore, the cooling load is a type of air conditioning load. Therefore, the difference between the measurement value θem from the intake temperature sensor (51) and the measurement value θsm from the outlet temperature sensor (52) (θem-θsm) is a load index L that correlates with the air conditioning load of the target space (70).

[0123] -Fourth variation- In the air conditioning systems (10) of Embodiments 1 and 2, the discharge unit (32) may be installed near the floor of the target space (70). In this modified example, the discharge unit (32) blows out air supplied from the processing unit (20) via the discharge duct (42) from an outlet facing the lower region (72) of the target space (70).

[0124] While embodiments and modifications have been described above, it will be understood that various changes in form and details are possible without departing from the spirit and scope of the claims. Furthermore, elements of the embodiments, modifications, and other embodiments described above may be combined or substituted as appropriate. In addition, the terms "first" and "second" in the specification and claims are used to distinguish the phrases to which these terms are attached, and do not limit the number or order of such phrases. [Industrial applicability]

[0125] As explained above, this disclosure is useful for air conditioning systems. [Explanation of Symbols]

[0126] 10. Air conditioning system 20 processing units 31 Suction Unit 32 Air outlet units 60 Controllers 70 Target space

Claims

1. An air conditioning system (10) comprising a processing unit (20) that draws in air and adjusts its temperature, the processing unit (20) blows the temperature-adjusted air into a target space (70), and forms a temperature stratification in the target space (70), The system includes a controller (60) that performs a first control operation when the load index correlated with the air conditioning load of the target space (70) is lower than a reference value, and a second control operation when the load index is higher than the reference value. The flow rate of air that the above-mentioned air conditioning system (10) blows into the above-mentioned target space (70) is the discharge flow rate. The temperature of the air that the above-mentioned air conditioning system (10) blows into the above-mentioned target space (70) is the outlet temperature. The above-described first control operation is an operation to maintain the discharge flow rate at the first flow rate and to adjust the discharge temperature so that the temperature of the target space (70) reaches the set temperature. The second control operation described above is an operation to maintain the discharge temperature at the first temperature and adjust the discharge flow rate so that the temperature of the target space (70) reaches the set temperature. Air conditioning system.

2. An air conditioning system (10) comprising a processing unit (20) that draws in air and adjusts its temperature, the processing unit (20) blows the temperature-adjusted air into a target space (70), and forms a temperature stratification in the target space (70), The system includes a controller (60) that performs a first control operation when the load index correlated with the air conditioning load of the target space (70) is lower than a reference value, and a second control operation when the load index is higher than the reference value. The flow rate of air that the above-mentioned air conditioning system (10) blows into the above-mentioned target space (70) is the discharge flow rate. The temperature of the air that the above-mentioned air conditioning system (10) blows into the above-mentioned target space (70) is the outlet temperature. The above-described first control operation is an operation to maintain the discharge flow rate at the first flow rate and to adjust the discharge temperature so that the temperature of the target space (70) reaches the set temperature. The second control operation described above is an operation to maintain the discharge flow rate at a second flow rate that is greater than the first flow rate, and to adjust the discharge temperature so that the temperature of the target space (70) reaches the set temperature. Air conditioning system.

3. The above processing unit (20) supplies temperature-controlled air to the lower part of the target space (70) via a blowing unit (32), The system includes a suction unit (31) that draws in air from the upper part of the target space (70) described above. The air conditioning system according to claim 1 or 2.

4. The above-mentioned blowing unit (32) is installed at the top of the target space (70) and supplies the air whose temperature has been controlled by the processing unit (20) to the lower part of the target space (70) by blowing it toward the floor of the target space (70). The air conditioning system according to claim 3.

5. The above load index is the difference between the temperature of the target space and the outlet temperature. The air conditioning system according to claim 1 or 2.

6. The above load index is the difference between the temperature of the air drawn in by the intake unit (31) from the target space (70) and the discharge temperature. The air conditioning system according to claim 3.

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