Air conditioning system

Abstract

The present invention provides an air conditioning system that can reduce the temperature difference between the temperature-controlled air blown out from the outlet and the room temperature while maintaining the heating and cooling effect within the living space. [Solution] The air conditioning system 10 includes an underfloor space 4 provided beneath the floor 2A of the living room 2, an air outlet 5 positioned on the floor 2A of the living room 2 and supplying first temperature-controlled air CA1 from the underfloor space 4 to the living room 2, a return air intake 14 for taking in return air RA1 from the living room 2, an air conditioner 12 that supplies second temperature-controlled air CA2, which is air containing return air RA1 having a first airflow rate and whose temperature has been adjusted, to the underfloor space 4, and a fan 13 that supplies return air RA1 having a second airflow rate to the underfloor space 4. In the underfloor space 4, air mixed with the second temperature-controlled air CA2 supplied from the air conditioner 12 and the return air RA1 supplied from the fan 13 is supplied as the first temperature-controlled air CA1.

Description

[Technical Field]

[0001] This disclosure relates to an air conditioning system that blows air from an outlet installed in the floor of a living room. [Background technology]

[0002] As an air conditioning system for offices and other spaces, a technology is known in which temperature-controlled air, whose temperature has been adjusted by an air conditioner, is blown out from an outlet installed in the floor of the room (see Patent Document 1). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2024-17851 [Overview of the project] [Problems that the invention aims to solve]

[0004] Compared to blowing conditioned air from an outlet in the ceiling, blowing conditioned air from an outlet in the floor means the distance from the outlet to the person in the room is shorter. Therefore, if there is a large temperature difference between the conditioned air blown from the outlet and the room temperature, it may cause discomfort to the person in the room. [Means for solving the problem]

[0005] An air conditioning system that solves the above problems comprises an underfloor space provided beneath the floor of a living room; an air outlet positioned on the floor of the living room and supplying a first temperature-controlled air from the underfloor space to the living room; a return air intake for taking in return air from the living room; an air conditioner that supplies a second temperature-controlled air to the underfloor space, which is air containing a first volume of the return air taken in from the return air intake, with its temperature adjusted; and a fan that supplies a second volume of the return air taken in from the return air intake to the underfloor space. The underfloor space is supplied with air mixed with the second temperature-controlled air supplied by the air conditioner and the second volume of the return air supplied by the fan, which is then supplied as the first temperature-controlled air. [Effects of the Invention]

[0006] According to this disclosure, it is possible to reduce the temperature difference between the temperature-controlled air blown out from the outlet and the room temperature while maintaining the heating and cooling effect in the room. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 is a schematic diagram showing the configuration of an air conditioning system. [Modes for carrying out the invention]

[0008] [Air conditioning system] An embodiment of the air conditioning system will be described below with reference to Figure 1. As shown in Figure 1, the air conditioning system 10 provides air conditioning to a room 2 in building 1. A room 2 is, for example, a space where one or more occupants 3 can stay, and is a large space such as an office.

[0009] The air conditioning system 10 includes an underfloor space 4 located beneath the floor 2A of the living room 2, and a plurality of air outlets 5 positioned on the floor 2A of the living room 2. The air outlets 5 supply first temperature-controlled air CA1 from the underfloor space 4 to the living room 2. The first temperature-controlled air CA1 is air whose temperature and humidity have been adjusted by a device located in the machine room 6 of the building 1. The air outlets 5 may be configured to allow adjustment of their opening degree.

[0010] The air conditioning system 10 includes a total heat exchanger 11, an air conditioner 12, and a fan 13 as devices for supplying the first temperature-controlled air CA1. These devices are located in the machine room 6. The air conditioning system 10 includes a return air intake 14 for taking in return air RA1 from the living room 2 and an outside air intake 15 for taking in outside air OA1. The return air RA1 from the living room 2 is supplied to each of the total heat exchanger 11, the air conditioner 12, and the fan 13 through the return air intake 14. In addition, outside air OA1 is supplied to the total heat exchanger 11 through the outside air intake 15.

[0011] The total heat exchanger 11 adjusts the temperature of the outside air OA1 by performing heat exchange between a portion of the return air RA1 taken in from the return air intake port 14 and the outside air OA1 taken in from the outside air intake port 15. As a result, the outside air OA1 is pre-cooled during cooling operation and pre-heated during heating operation. Hereafter, the outside air OA1 whose temperature has been adjusted by the total heat exchanger 11 will be referred to as temperature-controlled outside air OA2. The total heat exchanger 11 supplies the temperature-controlled outside air OA2 to the air conditioner 12. The return air RA1 used for heat exchange in the total heat exchanger 11 is discharged outside through the exhaust port 16.

[0012] The air conditioner 12 is, for example, a packaged air conditioner using a direct expansion (DX) method with a refrigerant. A packaged air conditioner refers to an air conditioning unit in which the outdoor unit and indoor unit are integrated. The air conditioner 12 supplies second temperature-controlled air CA2, which is a mixture of a portion of the return air RA1 taken in from the return air intake port 14 and the temperature-controlled outdoor air OA2 supplied from the total heat exchanger 11, with the temperature of the mixed air adjusted. The second temperature-controlled air CA2 is supplied from the air conditioner 12 to the mixing unit 17. The air conditioner 12 supplies a constant volume of second temperature-controlled air CA2 to ensure constant ventilation in the living room 2.

[0013] The fan 13 supplies a part of the return air RA1 taken in from the return air intake 14 to the mixing section 17. As a result, in the mixing section 17, the second temperature-controlled air CA2 supplied from the air conditioner 12 and the return air RA1 supplied from the fan 13 are mixed. The second temperature-controlled air CA2 and the return air RA1 mixed in the mixing section 17 are supplied to the underfloor space 4 as the first temperature-controlled air CA1. By supplying the first temperature-controlled air CA1 to the underfloor space 4, the underfloor space 4 becomes positively pressurized, and the first temperature-controlled air CA1 blows out from the air outlet 5 into the living room 2.

[0014] Note that, for the purpose of always ventilating the living room 2, a constant amount or more of the first temperature-controlled air CA1 is always supplied to the living room 2. For example, by providing a lower limit value for the opening degree of each air outlet 5, it may be configured such that a constant amount or more of the first temperature-controlled air CA1 is always supplied toward the living room 2. Also, in order to always supply a constant amount or more of the first temperature-controlled air CA1 toward the living room 2, a part of the plurality of air outlets 5 may be configured such that the opening degree cannot be adjusted.

[0015] The fan 13 supplies the return air RA1 with a constant air volume. For example, the air volume of the return air RA1 supplied by the fan 13 is 10% or more and 70% or less, preferably 20% or more and 60% or less, of the air volume of the second temperature-controlled air CA2 supplied by the air conditioner 12. Hereinafter, among the return air RA1 taken in from the return air intake 14, the air volume of the return air RA1 supplied to the air conditioner 12 is the first air volume, the air volume of the return air RA1 supplied to the mixing section 17 via the fan 13 is the second air volume, and the air volume of the return air RA1 supplied to the total heat exchanger 11 is the third air volume. That is, the return air RA1 with the total air volume of the first air volume, the second air volume, and the third air volume is taken in from the living room 2 through the return air intake 14.

[0016] The first temperature-controlled air CA1 supplied to the under-bed space 4 has a larger air volume than the second temperature-controlled air CA2 supplied from the air conditioner 12. As a result, compared with the case where only the second temperature-controlled air CA2 is supplied to the under-bed space 4, the pressure inside the under-bed space 4 increases more, so the air volume of the air blown out from the air outlet 5 increases. Also, the first temperature-controlled air CA1 has a temperature closer to the room temperature in the living room 2 than the second temperature-controlled air CA2 supplied from the air conditioner 12. Therefore, while maintaining the heating and cooling effect in the living room 2, the temperature difference between the first temperature-controlled air CA1 supplied from the air outlet 5 and the room temperature in the living room can be reduced.

[0017] [Method for setting the air volume of the fan 13] Hereinafter, a method for setting the second air volume of the return air RA1 supplied from the fan 13 will be described. The second air volume is set so that when the return air RA1 supplied from the fan 13 is mixed with the second temperature-controlled air CA2 supplied from the air conditioner 12, the mixed gas satisfies the required temperature as the first temperature-controlled air CA1 supplied from the air outlet 5.

[0018] Specifically, the second air volume is set based on the temperature and air volume of the second temperature-controlled air CA2 supplied when the air conditioner 12 operates at its rated capacity (unit: kW) under the conditions of a specific outside air temperature and a specific temperature of the return air RA1. The rated capacity is set according to the conditions compliant with, for example, JIS B8616:2015 and JRA4002:2016.

[0019] Therefore, when setting the second airflow rate, first, the temperature and airflow rate of the second temperature-controlled air CA2 supplied from the air conditioner 12 when the air conditioner 12 is operating at its rated capacity under specific conditions of ambient temperature and specific return air RA1 temperature. Then, the second airflow rate is set so that when the second temperature-controlled air CA2 having the specified temperature and airflow rate is mixed with the return air RA1 having the second airflow rate supplied from the fan 13, the resulting mixture satisfies the temperature required for the first temperature-controlled air CA1 supplied from the outlet 5. Note that the temperature of the first temperature-controlled air CA1 corresponds to the weighted average of the temperatures of the return air RA1 and the second temperature-controlled air CA2 before mixing, weighted by airflow. As the specific ambient temperature and return air RA1 temperature, for example, the cooling capacity test conditions or standard rated conditions for heating capacity tests specified in JIS B8615-1:2013 may be adopted. Furthermore, the specific ambient temperature and return air RA1 temperature are not limited to the above test conditions, but may be set appropriately considering the ambient temperature and return air RA1 temperature expected during actual use.

[0020] The airflow rate of the second temperature-controlled air CA2 is the airflow rate that the air conditioner 12 can process, for example, the rated airflow rate of the air conditioner 12. Furthermore, the airflow rate of the second temperature-controlled air CA2 corresponds to the sum of the airflow rate of the temperature-controlled outdoor air OA2 supplied from the total heat exchanger 11 to the air conditioner 12 and the first airflow rate of the return air RA1 supplied to the air conditioner 12. Note that the airflow rate of the temperature-controlled outdoor air OA2 is set appropriately according to the number of people who can stay in the room 2. Therefore, the first airflow rate of the return air RA1 supplied to the air conditioner 12 is calculated as the difference obtained by subtracting the airflow rate of the temperature-controlled outdoor air OA2 from the airflow rate that the air conditioner 12 can process.

[0021] The temperature of the second temperature-controlled air CA2 is calculated based on the airflow rate and temperature of the temperature-controlled outside air OA2, the first airflow rate and temperature of the return air RA1 supplied to the air conditioner 12, and the rated capacity and bypass factor of the air conditioner 12. The bypass factor refers to the ratio of the amount of bypass air that is discharged without heat exchange from the air taken into the air conditioner 12 to the total amount of intake air.

[0022] The following describes an example of a method for calculating the temperature of the second temperature-controlled air CA2. As an example, assume a case where cooling operation is performed under the conditions that the dry-bulb temperature of the outside air OA1 is 35°C DB and the dry-bulb temperature of the return air RA1 is 26°C DB. Also, assume that the humidity of both the outside air OA1 and the return air RA1 is 50% RH.

[0023] As specific examples of each parameter, assume that the rated capacity of the air conditioner 12 is 28 kW and the rated air volume of the air conditioner 12 is 5100 m 3 / h. Also, assume that the air volume of the temperature-controlled outside air OA2 required for ventilation is 1910 m 3 / h, and the first air volume of the return air RA1 supplied to the air conditioner 12 is 3190 m 3 / h. Assume that the dry-bulb temperature of the temperature-controlled outside air OA2 in the state pre-cooled by the total heat exchanger 11 is 29.3°C DB. Note that the dry-bulb temperature of the temperature-controlled outside air OA2 is calculated according to the assumed temperature of the outside air OA1, the temperature of the return air RA1 used for heat exchange, and the heat exchange efficiency of the total heat exchanger 11.

[0024] Under the above conditions, the air conditioner 12 is supplied with a combined air in which the temperature-controlled outside air OA2 with an air volume of 1910 m 3 / h and a dry-bulb temperature of 29.3°C DB and the return air RA1 with an air volume of 3190 m 3 / h and a dry-bulb temperature of 26.0°C DB are combined. At this time, the combined air has an air volume of 5100 m 3 / h and a temperature of 27.2°C DB. Note that the dry-bulb temperature of the combined air corresponds to the weighted average of the dry-bulb temperatures of the temperature-controlled outside air OA2 and the return air RA1 before combination, weighted by the air volume. Also, the specific enthalpy of the combined air (humidity: 50% RH) at this time is 57.2 kJ / kg.

[0025] Here, calculate the amount of heat removed from the combined air by the air conditioner 12, that is, the reduction amount of specific enthalpy (ΔH) by the air conditioner 12. The reduction amount of specific enthalpy by the air conditioner 12 is calculated as ΔH = 28 [kW] × 3600 [s] / (5100 [m 3 / h] / 0.83 [m 3 / kg]) = 16.4 [kJ / kg]. Note that 0.83 [m 3 / kg] represents the specific volume of air.

[0026] Furthermore, assuming a bypass factor of 0.13 for the air conditioner 12, the effective reduction in specific enthalpy due to the air conditioner 12 is calculated as 16.4 [kJ / kg] / (1 - 0.13) = 18.9 [kJ / kg]. Therefore, the specific enthalpy of the combined air cooled by the air conditioner 12 (i.e., the second temperature-controlled air CA2) is 57.2 - 18.9 = 38.3 [kJ / kg]. Calculating the temperature of the second temperature-controlled air CA2 based on its specific enthalpy using a psychrometric chart, it is determined to be 15.6°C DB.

[0027] The second airflow rate of the return air RA1 supplied from the fan 13 is set so that when the return air RA1 is mixed with the second temperature-controlled air CA2 having the temperature and airflow rate calculated in the above procedure, a first temperature-controlled air CA1 having the desired temperature is obtained.

[0028] For example, the temperature (15.6°C DB) and airflow (5100 m³) calculated in the example above 3 Let's assume a case where the dry-bulb temperature of the first temperature-controlled air CA1 is set to approximately 18°C ​​DB by mixing the return air RA1 from fan 13 with the second temperature-controlled air CA2 which has a volume of 1 / h. In this case, the second airflow rate of the return air RA1 supplied from fan 13 is 1380 m³. 3 Set to / h. This will set the airflow rate of the first temperature-controlled air CA1 to 1380[m³ 3 / h]+5100[m 3 / h]=6480m 3 It is calculated as / h. Also, the dry-bulb temperature of the first temperature-controlled air CA1 is (26[℃DB] × 1380[m 3 / h]+15.6[℃DB]×5100[m 3 / h]) / (1380[m 3 / h]+5100[m 3 / h]) ≈ 17.8℃ DB is calculated.

[0029] Therefore, as the temperature of the first temperature-controlled air CA1 rises by about 2°C compared to the second temperature-controlled air CA2, the temperature of the first temperature-controlled air CA1 blown out from the outlet 5 becomes closer to the room temperature, thus reducing the discomfort (feeling of coldness) caused to the occupant 3 when the first temperature-controlled air CA1 is blown out. In addition, although the temperature of the first temperature-controlled air CA1 is higher than that of the second temperature-controlled air CA2, the airflow is increased. Therefore, the cooling effect in the living room 2 by the first temperature-controlled air CA1 can be maintained.

[0030] (Effects of the embodiment) (1) In the air conditioning system 10, first temperature-controlled air CA1, which is a mixture of second temperature-controlled air CA2 supplied from the air conditioner 12 and return air RA1 supplied from the fan 13, is supplied to the underfloor space 4. The first temperature-controlled air CA1 supplied to the underfloor space 4 is then supplied into the living room 2 from the outlet 5. The first temperature-controlled air CA1 has a temperature closer to the room temperature in the living room 2 and a larger airflow compared to the second temperature-controlled air CA2 supplied from the air conditioner 12. Therefore, the pressure in the underfloor space 4 is higher than when only the second temperature-controlled air CA2 is supplied to the underfloor space 4, and the airflow of the first temperature-controlled air CA1 blown out from the outlet 5 increases. Thus, the temperature difference between the first temperature-controlled air CA1 supplied from the outlet 5 and the room temperature in the living room 2 is reduced while maintaining the heating and cooling effect in the living room 2.

[0031] (2) The air conditioner 12 adjusts the temperature of the combined air, which includes a portion of the return air RA1 and the outside air OA1, and supplies it to the mixing unit 17 as the second temperature-controlled air CA2. With this configuration, ventilation of the living room 2 can be performed using the air conditioning system 10. In addition, by supplying temperature-controlled outside air OA2, which is obtained by pre-cooling or pre-heating the outside air OA1 in the total heat exchanger 11, to the air conditioner 12, the energy efficiency of the air conditioning system 10 can be improved.

[0032] (3) When the air conditioner 12 is operating at its rated capacity, the temperature difference between the second temperature-controlled air CA2 supplied from the air conditioner 12 and the room temperature in the living room 2 is relatively large. Assuming this condition, the first temperature-controlled air CA1 supplied from the outlet 5 can be adjusted to a suitable temperature by setting the second airflow rate of the return air RA1 supplied from the fan 13 according to the rated capacity of the air conditioner 12.

[0033] (4) By using a direct expansion type package air conditioner as the air conditioner 12, power consumption can be reduced compared to using a chiller type air conditioner. In the case of a package air conditioner, while power consumption is relatively low, the degree of freedom in the amount of air that can be supplied is limited. Therefore, by using a fan 13 separately from the air conditioner 12, the air volume of the first temperature-controlled air CA1 supplied to the underfloor space 4 can be increased while taking advantage of the advantages of a package air conditioner. Even when using the air conditioner 12 as a package air conditioner and the fan 13 in combination in this way, power consumption can be reduced compared to using a chiller type air conditioner.

[0034] (5) The second airflow rate of the return air RA1 supplied by the fan 13 is, for example, 10% to 70% of the airflow rate of the second temperature-controlled air CA2 supplied by the air conditioner 12, preferably 20% to 60%. By setting the second airflow rate of the return air RA1 supplied by the fan 13 within the above range, the temperature difference between the first temperature-controlled air CA1 supplied from the outlet 5 and the room temperature in the living room 2 can be suitably reduced while maintaining the heating and cooling effect in the living room 2.

[0035] (Example of change) This embodiment can be implemented with the following modifications. This embodiment and the following modifications can be combined with each other to the extent that they do not contradict each other technically.

[0036] If the first temperature-controlled air CA1 supplied from the outlet 5 is adjusted to a suitable temperature, the second airflow rate of the return air RA1 supplied by the fan 13 may be set as appropriate. For example, the second airflow rate may be less than 10% or more than 70% of the airflow rate of the second temperature-controlled air CA2 supplied by the air conditioner 12. The second airflow rate may differ depending on whether the air conditioning system 10 is operating in cooling mode or heating mode. Furthermore, the configuration is not limited to setting the second airflow rate of the return air RA1 supplied from the fan 13 according to the rated capacity of the air conditioner 12. For example, the second airflow rate may be set so that the first temperature-controlled air CA1 supplied from the outlet 5 is adjusted to a suitable temperature when the air conditioner 12 is operating at any capacity below its rated capacity.

[0037] The air conditioner 12 is not limited to a direct expansion type packaged air conditioner. For example, the air conditioner 12 may be a chiller type air conditioner having a chiller unit. In this case as well, by combining the chiller type air conditioner 12 with the fan 13, the same effects as in (1) above can be obtained.

[0038] Instead of the configuration in which the air conditioner 12 adjusts the temperature of the combined air, which includes a portion of the return air RA1 and the outside air OA1, a ventilation system independent of the air conditioning system 10 may be provided. In this case, the air conditioner 12 can also be configured to adjust the temperature of only the return air RA1.

[0039] If a sufficient amount of outside air is supplied into the living room 2, the airflow rate of the second temperature-controlled air CA2 supplied from the air conditioner 12 may be variable rather than constant. For example, in the combined air supplied to the air conditioner 12, the airflow rate of the temperature-controlled outside air OA2 may be kept constant while the first airflow rate of the return air RA1 is made variable. In this case, the second airflow rate of the return air RA1 supplied by the fan 13 may be set according to, for example, the maximum value of the airflow rate of the second temperature-controlled air CA2.

[0040] If the first temperature-controlled air CA1 supplied from the outlet 5 is adjusted to a suitable temperature, the second airflow rate of the return air RA1 supplied by the fan 13 may be variable rather than constant. For example, the second airflow rate of the return air RA1 supplied by the fan 13 may be adjusted by controlling the output of the fan 13 so that the first temperature-controlled air CA1 supplied from the outlet 5 is adjusted to a suitable temperature according to the airflow rate and temperature of the second temperature-controlled air CA2 supplied from the air conditioner 12.

[0041] The fan 13 may be used in both cases: when the air conditioning system 10 is performing cooling operation and when the air conditioning system 10 is performing heating operation, or it may be used in only one of these cases. For example, (Note) The technical concepts that can be understood from the above embodiments and modified examples are described below.

[0042] (Note 1) The aforementioned air conditioner is a packaged air conditioner. The air conditioning system according to claim 1.

[0043] (Note 2) The airflow rate of the second temperature-controlled air supplied from the air conditioner is constant. The second airflow rate of the return air supplied from the fan is constant and is between 10% and 70% of the airflow rate of the second temperature-controlled air supplied from the air conditioner. The air conditioning system according to claim 1. [Explanation of Symbols]

[0044] CA1...First temperature-controlled air, CA2...Second temperature-controlled air, OA1...Outside air, OA2...Temperature-controlled outside air, RA1...Return air, 1...Building, 2...Living room, 2A...Floor, 3...Occupants, 4...Underfloor space, 5...Air outlet, 6...Machine room, 10...Air conditioning system, 11...Total heat exchanger, 12...Air conditioner, 13...Fan, 14...Return air intake, 15...Outside air intake, 16...Exhaust port, 17...Mixing unit.

Claims

1. The underfloor space located beneath the floor of the living room, An air outlet is provided in the floor of the aforementioned living room and supplies temperature-controlled first air from the underfloor space to the living room, A return air intake port for taking in return air from the aforementioned living room, An air conditioner that supplies a second temperature-controlled air to the underfloor space, which is air containing a first volume of the return air taken in from the return air intake port, with the temperature of the air adjusted. The system includes a fan that supplies a second volume of the return air taken in from the return air intake to the underfloor space, In the underfloor space, the first temperature-controlled air is supplied as a mixture of the second temperature-controlled air supplied from the air conditioner and the second volume of return air supplied from the fan. Air conditioning system.

2. An outside air intake for taking in outside air, The air conditioner further comprises a total heat exchanger that supplies temperature-controlled outside air to the air conditioner by performing heat exchange between a third volume of the return air taken in from the return air intake port and the outside air to adjust the temperature of the outside air. The air conditioner adjusts the temperature of the air, which includes the first volume of return air and the temperature-controlled outside air, taken in from the return air intake port, and supplies it as the second temperature-controlled air. The air conditioning system according to claim 1.

3. The airflow rate of the second temperature-controlled air supplied from the air conditioner is constant. The second airflow rate of the return air supplied from the fan is constant. The second airflow rate is set to satisfy the temperature required for the first temperature-controlled air supplied from the outlet, based on the temperature and airflow rate of the second temperature-controlled air supplied when the air conditioner is operating at its rated capacity under specific ambient temperature and specific return air temperature conditions. The air conditioning system according to claim 2.

Images