GB2622541A

GB2622541A - Heat exchange ventilator

Info

Publication number: GB2622541A
Application number: GB2400137.2A
Authority: GB
Inventors: Yasuda Masami
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2021-07-14
Filing date: 2021-07-14
Publication date: 2024-03-20
Also published as: GB202400137D0; JPWO2023286188A1; WO2023286188A1

Abstract

This heat exchange ventilator comprises: an air-supplying blower; an exhaust blower; a casing; a heat exchanger; a drain pan; a supplied airflow temperature sensor; a supplied airflow humidity sensor; an exhaust flow temperature sensor; an exhaust flow humidity sensor; and a control unit. The casing includes a supplied air path through which supplied airflow passes and an exhaust path through which exhaust flow passes. The heat exchanger exchanges heat between a supplied airflow and an exhaust flow. The drain pan retains water generated in the heat exchanger due to condensation, and drains the water. The supplied airflow temperature sensor detects the temperature of the supplied airflow. The supplied airflow humidity sensor detects the humidity of the supplied airflow. The exhaust flow temperature sensor detects the temperature of the exhaust flow. The exhaust flow humidity sensor detects the humidity of the exhaust flow. The control unit controls at least one of the air-supplying blower and the exhaust blower on the basis of a total amount of water that has been generated in the heat exchanger due to condensation and is present in the drain pan, the total amount of water being calculated on the basis of the temperature and the humidity of the supplied airflow and the temperature and the humidity of the exhaust flow.

Description

DESCRIPTION

TITLE OF THE INVENTION:

HEAT EXCHANGE VENTILATOR

Field

[0001] The present disclosure relates to a heat exchange ventilator that performs ventilation while exchanging heat between a supply air flow and an exhaust air flow.

Background

[0002] Patent Literature 1 discloses a heat exchange ventilator capable of switching between heat exchange ventilation operation and non-heat exchange ventilation operation. The heat exchange ventilation operation is an operation of room ventilation in which supply air for supplying outdoor air into the room and exhaust air for discharging indoor air out of the room flow through the heat exchanger so that heat is exchanged between the supply air and the exhaust air. The non-heat exchange ventilation operation is an operation in which outdoor air flows through a bypass passage without passing through the heat exchanger so that heat is not exchanged between the supply air and the exhaust air. The heat exchange ventilator described in Patent Literature 1 switches to the non-heat exchange ventilation operation when the humidity of the outdoor air is in a high humidity state, that is, higher than a predetermined value, during the heat exchange ventilation operation.

Citation List Patent Literature [0003] Patent Literature 1: Japanese Patent Application Laid-open No. 2011-220561

Summary

Technical Problem [0004] The heat exchange ventilator described in Patent Literature 1 switches from the heat exchange ventilation operation to the non-heat exchange ventilation operation when determining that the humidity of the outdoor air is so high that the heat exchanger can get wet. Thus, although the ventilation can be continued, switching to the non-heat exchange ventilation operation has the problem in that energy saving performance is poor during the non-heat exchange ventilation operation. In addition, the heat exchange ventilator described in Patent Literature 1 determines the operating condition based on the air conditions only. Thus, the heat exchange ventilator described in Patent Literature I also has the problem in that energy saving performance is poor because control for protecting the product is performed at an earlier stage than the conditions with which the product can withstand.

For example, when the technique described in Patent Literature 1 is applied to a heat exchange ventilator including a drain pan that stores dew condensation water generated in the heat exchanger, the operation is controlled only based on the humidity of the outdoor air regardless of the amount of dew condensation water accumulated in the drain pan. Therefore, although the heat exchange ventilation operation can be performed until the water in the drain pan reaches a predetermined water level, the non-heat exchange ventilation operation is executed beforehand, which results in the problem of poor performance in energy saving.

[0005] The present disclosure has been made in view of the above, and an object thereof is to obtain a heat exchange ventilator capable of performing ventilation without causing overflow of water from the drain pan while achieving energy saving performance higher than before in a situation where dew condensation water is constantly generated from the heat exchanger.

Solution to Problem [0006] In order to solve the above-described problems and achieve the object, a heat exchange ventilator according to the present disclosure includes a supply blower, an exhaust blower, a casing, a heat exchanger, a drain pan, a supply air flow temperature sensor, a supply air flow humidity sensor, an exhaust air flow temperature sensor, an exhaust air flow humidity sensor, and a control unit. The casing includes a supply air passage through which a supply air flow from an outdoor space to an indoor space formed by the supply blower passes, and an exhaust air passage through which an exhaust air flow from an indoor space to an outdoor space formed by the exhaust blower passes. The heat exchanger is disposed between the supply air passage and the exhaust air passage, and exchanges heat between the supply air flow and the exhaust air flow. The drain pan holds and drains water generated by dew condensation in the heat exchanger. The supply air flow temperature sensor detects the temperature of the supply air flow. The supply air flow humidity sensor detects the humidity of the supply air flow. The exhaust air flow temperature sensor detects the temperature of the exhaust air flow. The exhaust air flow humidity sensor detects the humidity of the exhaust air flow. The control unit controls the supply blower and/or the exhaust blower based on the total amount of water generated by dew condensation in the heat exchanger and present in the drain pan, the total amount of water being calculated based on the temperature and the humidity of the supply air flow and the temperature and the humidity of the exhaust air flow.

Advantageous Effects of Invention [0007] The heat exchange ventilator according to the present disclosure can achieve the effect of performing ventilation without causing overflow of water from the drain pan while achieving energy saving performance higher than before in a situation where dew condensation water is constantly generated from the heat exchanger.

Brief Description of Drawings

[0008] FIG. 1 is a perspective side view schematically illustrating an exemplary configuration of a heat exchange ventilator according to a first embodiment.

FIG. 2 is a perspective view illustrating an exemplary configuration of a heat exchanger.

FIG. 3 is a diagram schematically illustrating the heat exchange ventilator according to the first embodiment in which the air passage switching damper is open.

FIG. 4 is a control block diagram illustrating an example of control of the heat exchange ventilator 25 according to the first embodiment.

FIG. 5 is a diagram schematically illustrating an example of a state in which dew condensation water is generated in the heat exchange ventilator according to the first embodiment.

FIG. 6 is a flowchart illustrating an example of a procedure for control processing of the heat exchange ventilator according to the first embodiment.

FIG. 7 is a flowchart illustrating an example of a procedure for control processing of the heat exchange ventilator according to the first embodiment.

FIG. 8 is a diagram schematically illustrating an exemplary configuration of a heat exchange ventilator 5 according to a second embodiment.

FIG. 9 is a diagram illustrating an example of the relationship between the total amount of water and the corresponding air volume required in the heat exchange ventilator according to the second embodiment.

FIG. 10 is a diagram illustrating an example of the relationship between the CO., concentration in the indoor space and the corresponding air volume required in the heat exchange ventilator according to the second embodiment. FIG. 11 is a flowchart illustrating an example of a 15 procedure for control processing of the heat exchange ventilator according to the second embodiment.

FIG. 12 is a block diagram illustrating an exemplary hardware configuration of the control unit of the heat exchange ventilator according to the first and second 20 embodiments.

Description of Embodiments

[0009] Hereinafter, a heat exchange ventilator according to embodiments of the present disclosure will be described 25 in detail based on the drawings.

[0010] First Embodiment.

FIG. 1 is a perspective side view schematically illustrating an exemplary configuration of a heat exchange ventilator according to the first embodiment. The heat exchange ventilator 1 includes a body casing 11, an exhaust blower 12E, a supply blower 125, a heat exchanger 13, an outdoor air (OA) temperature sensor 14, an OA humidity sensor 15, a return air (RA) temperature sensor 16, an RA humidity sensor 17, a drain pan 18, an air passage switching damper 19, a remote controller 20, and a control circuit unit 30. Hereinafter, the remote controller 20 is referred to as the remote 20.

[0011] The body casing 11 has a box-shaped structure forming the outer shell of the heat exchange ventilator 1. The body casing 11 has a rectangular parallelepiped shape in one example. The body casing 11 corresponds to a casing. The body casing 11 includes an outdoor air inlet 111 and an exhaust air outlet 112 provided at one end surface ha in the longitudinal direction of the body casing 11. The body casing 11 includes a supply air outlet 113 and an indoor air inlet 114 provided at the other end surface llb facing the one end surface ha in the longitudinal direction of the body casing 11.

[0012] The body casing 11 includes a supply air passage and an exhaust air passage 116 therein. The supply air passage 115 is an air passage that connects the outdoor air inlet 111 and the supply air outlet 113, and through which a supply air flow SF, i.e. a flow of air from the outdoor space to the indoor space formed by the supply blower 125, passes. The exhaust air passage 116 is an air passage that connects the indoor air inlet 114 and the exhaust air outlet 112, and through which an exhaust air flow EF, i.e. a flow of air from the indoor space to the outdoor space formed by the exhaust blower 12E, passes. The heat exchanger 13 is disposed between the supply air passage 115 and the exhaust air passage 116, extending across the supply air passage 115 and the exhaust air passage 116.

Hereinafter, in the supply air passage 115, the portion on the windward of the heat exchanger 13 is called the windward supply air passage 115a, and the portion on the leeward is called the leeward supply air passage 115b. In the exhaust air passage 116, the portion on the windward side of the heat exchanger 13 is called the windward exhaust air passage 116a, and the portion on the leeward is called the leeward exhaust air passage 116b. In addition to the air passage through the heat exchanger 13, the exhaust air passage 116 includes a bypass air passage 116c that does not run through the heat exchanger 13.

[0013] The supply blower 125 is disposed in the supply air passage 115 and forms the supply air flow SF. The exhaust blower 12E is disposed in the exhaust air passage 116 and forms the exhaust air flow SF. The supply blower 12S and the exhaust blower 12E can change the air volume in multiple levels. In the example of FIG. 1, the supply blower 12S is disposed in the leeward supply air passage 115b, and the exhaust blower 12E is disposed in the leeward exhaust air passage 116b. The air volume of the supply blower 125 and the exhaust blower 12E can be freely changed based on the settings and controls from the remote 20. Hereinafter, the supply blower 125 and the exhaust blower 12E are referred to as the blowers 12 unless they are distinguished from each other.

[0014] The heat exchanger 13 is disposed between the supply air passage 115 and the exhaust air passage 116, and continuously exchanges heat between the supply air flow SF and the exhaust air flow ES. The heat exchanger 13 may be a sensible heat exchanger that exchanges sensible heat, that is, temperature, between the supply air flow SF and the exhaust air flow EF, or may be a total heat exchanger that exchanges sensible heat and latent heat, that is, temperature and humidity, between the supply air flow SF and the exhaust air flow SF. Here, an example in which the heat exchanger 13 is a sensible heat exchanger will be described.

[0015] FIG. 2 is a perspective view illustrating an exemplary configuration of a heat exchanger. FIG. 2 illustrates the heat exchanger 13 of the cross-flow type in which the traveling directions of the exhaust air flow EF and the supply air flow SF passing through the heat exchanger 13 are perpendicular to each other. The heat exchanger 13 Includes a plurality of sheet materials 131 disposed at intervals, and spacing members 132 that hold the intervals among the plurality of sheet materials 131.

The heat exchanger 13 is a stack of the sheet materials 131 and the spacing members 132. The sheet material 131 is a plate-like member worked to be flat. The spacing member 132 is a sheet-like member with corrugated irregularities. The sheet material 131 and the spacing member 132 are joined to each other.

[0016] The spacing member 132 includes a spacing member 132a and a spacing member 132b oriented differently such that the directions of the folds of the corrugations are perpendicular to each other. The space formed between the spacing member 132a and the sheet material 131 is a primary air passage 133a through which the exhaust air flow EF passes. The space formed between the spacing member 132b and the sheet material 131 is a secondary air passage 133b through which the supply air flow SF passes. In the heat exchanger 13, a plurality of primary air passages 133a and a plurality of secondary air passages 133b are formed. The sheet materials 131, the spacing members 132a each constituting the primary air passages 133a, and the spacing members 132b each constituting the secondary air passages 133b are stacked in the thickness direction of the sheet material 131.

[0017] when the heat exchanger 13 is a sensible heat exchanger, the spacing member 132 is made of a material having gas shielding property but not moisture permeability. In this case, in the sheet material 131, only heat exchange, that is, sensible heat exchange, is performed between the exhaust air flow EF passing through the primary air passage 133a and the supply air flow SF passing through the secondary air passage 133b without mixing the exhaust air flow EF and the supply air flow SF, and heat exchange ventilation can be performed. At this time, if the treated air exceeds the dew point temperature, dew condensation water which is water resulting from dew condensation is generated from the heat exchanger 13.

[0018] The air flowing through the supply air passage and the exhaust air passage 116 is classified into the following four types depending on whether it is positioned prior to or subsequent to the heat exchanger 13. The air flowing through the windward supply air passage 115a is referred to as outdoor air OA, the air flowing through the leeward supply air passage 115b is referred to as supply air SA, the air flowing through the windward exhaust air passage 116a is referred to as return air RA, and the air flowing through the leeward exhaust air passage 116b is referred to as exhaust air EA. The supply air flow SF is a flow of the outdoor air OA before the heat exchanger 13, and a flow of the supply air SA after the heat exchanger 13. The exhaust air flow EF is a flow of the return air RA before the heat exchanger 13, and a flow of the exhaust air EA after the heat exchanger 13.

[0019] Returning to FIG. 1, the OA temperature sensor 14 and the OA humidity sensor 15 are provided on the windward of the heat exchanger 13 in the supply air passage 115, that is, in the windward supply air passage 115a, and are connected to the control circuit unit 30 via wiring. The OA temperature sensor 14 detects the temperature of the outdoor air OA, and transmits detection results to the control circuit unit 30 at predetermined time intervals. The OA humidity sensor 15 detects the humidity of the outdoor air OA, and transmits detection results to the control circuit unit 30 at predetermined time intervals. The OA humidity sensor 15 detects the relative humidity. The OA temperature sensor 14 corresponds to a supply air flow temperature sensor that detects the temperature of the supply air flow SF, and the OR humidity sensor 15 corresponds to a supply air flow humidity sensor that detects the humidity of the supply air flow SF.

[0020] The RA temperature sensor 16 and the RA humidity sensor 17 are provided on the windward of the heat exchanger 13 in the exhaust air passage 116, that is, in the windward exhaust air passage 116a, and are connected to the control circuit unit 30 via wiring. The RA temperature sensor 16 detects the temperature of the return air RA, and transmits detection results to the control circuit unit 30 at predetermined time intervals. The RA humidity sensor 17 detects the humidity of the return air RA, and transmits detection results to the control circuit unit 30 at predetermined time intervals. The RA humidity sensor 17 detects the relative humidity. The RA temperature sensor 16 corresponds to an exhaust air flow temperature sensor that detects the temperature of the exhaust air flow SF, and the RA humidity sensor 17 corresponds to an exhaust air flow humidity sensor that detects the humidity of the exhaust air flow SF.

[0021] The drain pan 18 is provided so as to include at least a portion below the installation position of the heat exchanger 13 inside the body casing 11. The drain pan 18 holds and drains water generated by dew condensation in the heat exchanger 13. The drain pan 18 includes a drain port 181 for draining water stored in the drain pan 18 to the outside.

[0022] The air passage switching damper 19 is provided on the windward of the exhaust air passage 116, that is, in the windward exhaust air passage 116a. The air passage switching damper 19 switches between: allowing the exhaust air flow EF to pass through the heat exchanger 13, and allowing the exhaust air flow EF to pass through the bypass air passage 116c without passing through the heat exchanger 13 to directly send the exhaust air flow EF to the exhaust blower 12E. Here, when the air passage switching damper 19 is closed to block the bypass air passage 116c SD that the exhaust air flow EF passes through the heat exchanger 13, the exhaust air flow EF passes through the heat exchanger 13 and continuously exchanges heat with the supply air flow SF. When the air passage switching damper 19 is open to block the air passage to the heat exchanger 13 so that the exhaust air flow EF passes through the bypass air passage 116c, the exhaust air flow EF is discharged outdoors via the exhaust blower 12E as non-heat exchange ventilation.

[0023] Switching between opening and closing of the air passage switching damper 19 is manually performed by settings from the remote 20, for example. Alternatively, switching between opening and closing of the air passage switching damper 19 may be performed in accordance with an instruction from the control circuit unit 30 when it is determined, using the temperatures detected by the OA temperature sensor 14 and the RA temperature sensor 16, that the temperature of the outdoor air OA is lower than the indoor temperature similarly to the case of cooling with outdoor air. FIG. 1 illustrates a situation when the air passage switching damper 19 is closed. In FIG. 1, the return air RA drawn in from the indoor air inlet 114 passes through the windward exhaust air passage 116a, the heat exchanger 13, and the leeward exhaust air passage 116b inside the body casing 11, and is discharged outdoors as the exhaust air EA from the exhaust air outlet 112. On the other hand, the outdoor air OA always passes through the heat exchanger 13, and thus the return air RA exchanges heat with the outdoor air OA in the heat exchanger 13.

[0024] FIG. 3 is a diagram schematically illustrating the heat exchange ventilator according to the first embodiment in which the air passage switching damper is open. When the air passage switching damper 19 is open, the air passage switching damper 19 closes the air passage from the indoor air inlet 114 to the heat exchanger 13. Therefore, the return air RA drawn in from the indoor air inlet 114 passes through the windward exhaust air passage 116a, the bypass air passage 116c, and the leeward exhaust air passage 116b inside the body casing 11, and is discharged outdoors as the exhaust air EA from the exhaust air outlet 112. Therefore, the return air RA does not exchange heat with the outdoor air OA, which always passes through the heat exchanger 13, and non-heat exchange ventilation is performed.

[0025] Returning to FIG. 1, the remote 20 provides the control circuit unit 30 with an instruction including the settings set by the user (not illustrated) regarding ventilation in the room equipped with the heat exchange ventilator 1. The remote 20 is connected to the control circuit unit 30 in a wired or wireless manner.

[0026] The control circuit unit 30 controls the operation of the heat exchange ventilator 1 in accordance with the user's instruction determined by the user operating the remote 20. The control circuit unit 30 corresponds to a control unit. FIG. 4 is a control block diagram illustrating an example of the heat exchange ventilator according to the first embodiment. As illustrated in FIG. 4, the control circuit unit 30 is connected to the exhaust blower 12E, the supply blower 12S, the OA temperature sensor 14, the OA humidity sensor 15, the RA temperature sensor 16, the RA humidity sensor 17, the air passage switching damper 19, and the remote 20 via wiring. The wiring may be wired or wireless.

[0027] In the first embodiment, the control circuit unit 30 controls the operations of the blowers 12 and the air passage switching damper 19 based on the user's instruction from the remote 20 and the temperatures and humidities detected by the OA temperature sensor 14, the OA humidity sensor 15, the RA temperature sensor 16, and the RA humidity sensor 17. Specifically, the control circuit unit calculates the amount of dew condensation water generated in the heat exchanger 13, based on the temperature and humidity of the supply air flow SF detected by the OA temperature sensor 14 and the OA humidity sensor 15, and based on the temperature and humidity of the exhaust air flow EF detected by the RA temperature sensor 16 and the RA humidity sensor 17. The control circuit unit 30 further calculates the total amount of water generated by dew condensation stored in the drain pan 18 from the start of the operation to the calculation time point using the amount of drainage of dew condensation water from the drain pan 18. Then, the control circuit unit 30 controls the air volume of the blowers 12 based on the total amount of water generated by dew condensation so as to prevent overflow of water from the drain pan 18. In addition, when the water generated by dew condensation is likely to overflow from the drain pan 18, the control circuit unit 30 opens the air passage switching damper 19 to allow the return air RA to pass through the bypass air passage 116c without passing through the heat exchanger 13.

[0028] The first embodiment describes the operation of the sensible heat exchanger that exchanges only temperature. In winter, only sensible heat of the outdoor air OA is recovered by the heat exchanger 13; therefore, only the temperature of the supply air SA increases, but the absolute humidity of the supply air SA does not change. On the other hand, the return air RA, which is indoor air, passes through the heat exchanger 13 to undergo a decrease only in the temperature with its absolute humidity remaining unchanged, so that the exhaust air EA may exceed the dew point temperature. In this case, dew condensation water is generated from the heat exchanger 13. FIG. 5 is a diagram schematically illustrating an example of a state in which dew condensation water is generated in the heat exchange ventilator according to the first embodiment. Note that components identical to those in FIGS. 1 and 3 are denoted by the same reference signs, and the description thereof will be omitted. The generated dew condensation water 60 drops onto the drain pan 18. The dew condensation water 60 is collected to the drain port 181 provided in the drain pan 18, and drained to the outside of the heat exchanger 13.

[0029] Next, a control algorithm will be described in which the control circuit unit 30 performs heat exchange ventilation while achieving energy saving performance that is higher than before without causing overflow of dew condensation water from the drain pan 18. FIGS. 6 and 7 are flowcharts illustrating an example of a procedure for control processing of the heat exchange ventilator according to the first embodiment.

[0030] First, the control circuit unit 30 stores in advance values set for the operating air volume, the sensible heat exchange efficiency of the heat exchanger 13, the capacity and the amount of drainage of the drain pan 18, and the calculation target time (step S11). In one example, the calculation target time is the period from the acquisition of the previous detection results from the sensors to the acquisition of the current detection results from the sensors. The calculation target time can be determined in accordance with the communication state of the installed sensors, and the temperature change and humidity change in the indoor space to be ventilated or air-conditioned. In one example, the calculation target time may be the period between the measurement timings of the sensors, or may have a freely determined period at regular intervals if the measurement frequency of the sensors is high. In one example, the calculation target time can be about one minute.

[0031] Next, the control circuit unit 30 receives, from the remote 20, an operation command including an operation 20 mode indicating the operation state of the heat exchange ventilator 1 (step S12). Specifically, the operation command is a command to start the operation of the heat exchange ventilator 1 including a ventilation mode indicating the air volume and the type of ventilation. The ventilation mode is heat exchange ventilation operation or non-heat exchange ventilation operation. Thereafter, the control circuit unit 30 starts the operation in the operation mode included in the operation command (step S13). That is, the control circuit unit 30 starts the operation of the exhaust blower 12E and the operation of the supply blower 125 based on the air volume included in the operation command from the remote 20, and controls the opening and closing of the bypass air passage 116c, that is, the operation of the air passage switching damper 19, based on the ventilation mode included in the operation command from the remote 20.

[0032] Here, the control circuit unit 30 starts the operation in the operation mode included in the operation command by receiving the operation command from the remote 20, but the start of the operation in the operation mode is not limited to that by the remote 20. In one example, the control circuit unit 30 may include a timer, and the operation mode included in the operation command may be automatically started at a time set in advance by the remote 20.

[0033] After the start of the operation, the OA temperature sensor 14 and the RA temperature sensor 16 each measure the temperature, and the OA humidity sensor 15 and the RA humidity sensor 17 each measure the humidity. The control circuit unit 30 receives temperature information as detection results from the OA temperature sensor 14 and the RA temperature sensor 16 at predetermined time intervals, and receives humidity information as detection results from the OA humidity sensor 15 and the RA humidity sensor 17 (step S14). Because the OA humidity sensor 15 and the RA humidity sensor 17 generally measure the relative humidity, the control circuit unit 30 converts the relative humidity into absolute humidity. Hereinafter, the temperature measured by the OA temperature sensor 14 is referred to as an OA temperature measurement value, the humidity measured by the OA humidity sensor 15 is referred to as an OA humidity measurement value, the temperature measured by the RA temperature sensor 16 is referred to as an RA temperature measurement value, and the humidity measured by the RA humidity sensor 17 is referred to as an RA humidity measurement value. The OA temperature measurement value corresponds to the temperature of the supply air flow SF, and the OA humidity measurement value corresponds to the humidity of the supply air flow SF. The RA temperature measurement value corresponds to the temperature of the exhaust air flow FE', and the RA humidity measurement value corresponds to the humidity of the exhaust air flow EF.

[0034] Thereafter, the control circuit unit 30 calculates the temperature and the absolute humidity of the exhaust air EA from the OA temperature measurement value, the OA humidity measurement value, the RA temperature measurement value, and the RA humidity measurement value received in step 514 (step S15). The control circuit unit 30 calculates the temperature 112k of the exhaust air EA using the sensible heat exchange efficiency stored in advance. On the other hand, because humidity recovery is not performed in the heat exchanger 13, the absolute humidity AHE;, of the exhaust air EA is calculated to be the same as the absolute humidity AHF,, of RA.

[0035] Next, the control circuit unit 30 calculates the absolute humidity AHDEF at which the temperature TEA of the exhaust air EA is the dew point temperature (step S16). The dew point temperature is calculated as the value at which the relative humidity is 100(b. Hereinafter, when the temperature TEA of the exhaust air EA is the dew point temperature, the temperature T1, of the exhaust air EA is referred to as the exhaust air (EA) dew point temperature [0036] Further, the control circuit unit 30 calculates the amount of dew condensation water ME per unit time generated by heat exchange (step S17). The amount of dew condensation water Mw per unit time is calculated by multiplying the difference between the obtained absolute humidity AHEA of the exhaust air EA and the absolute humidity at the EA dew point temperature T. by the air density p and the exhaust air volume Q, as shown by Formula (1) below.

[0037] m,=pxQx(AH n-A1-1) (1) [0038] Here, when the amount of dew condensation water per unit time is MF>0, it means that dew condensation water is actually generated from the exhaust air EA, and when the amount of dew condensation water per unit time is it means that no dew condensation water is generated.

[0039] Next, the control circuit unit 30 calculates the amount of generated water Min, which is the amount of water generated during the calculation target time stored in advance, from the amount of dew condensation water Mw per unit time (step S18). The amount of generated water M n is calculated by multiplying the amount of dew condensation water My, per unit time by the calculation target time t, as shown by Formula (2) below. As described above, the calculation target time t is determined according to the communication state of the OA temperature sensor 14, the OA humidity sensor 15, the RA temperature sensor 16, and the RA humidity sensor 17 installed, and the temperature change or humidity change in the indoor space that is used for ventilation or air conditioning. The amount of generated water Mir calculated here corresponds to the change in the amount of dew condensation water M, during the calculation target time t from the time point of the last calculation of the amount of generated water Mi).

[0040] M_n=My,xt... (2) [0041] Thereafter, the control circuit unit 30 calculates the amount of water M actually remaining in the drain pan 18 during the calculation target time (step 319). The amount of water M remaining in the drain pan 18 during the calculation target time t is obtained as the difference between the amount of generated water M, and the amount of water 140L L discharged from the drain pan 18 during the calculation target time t, as shown by Formula (3) below.

[0042] ..' (3) [0043] Here, M>0 means that water is accumulated in the drain pan 18, and conversely, Fil0 means that water is not accumulated in the drain pan 18 because the amount of drainage is larger. Note that M c is the amount of drainage during the calculation target time t, and is a value obtained from the diameter of the drain port 181 and the number of drain ports 181, for example. Normally, the value is stored in the memory in the control circuit unit 30 as a product-specific value.

[0044] When the OA temperature measurement value TOA is equal to or higher than 0°C, that is, when TOAO, the water generated in the heat exchanger 13 and the water to be drained do not freeze. Therefore, the amount of water M actually remaining in the drain pan 18 is calculated simply using Formula (3). However, under the condition that the OA temperature measurement value TOA is below the freezing point, that is, when TOA<O, there is a possibility that the water generated in the heat exchanger 13 and the drainage water can freeze and cannot drop on the drain pan 16, or that water can freeze on the drain pan 18 and cannot be discharged from the drain pan 18. When TOA<O, the control circuit unit 30 assumes that all the amount of generated water Mir is accumulated, and sets [0045] Thereafter, the control circuit unit 30 integrates the amount of water M accumulated in the product, that is, in the heat exchange ventilator 1, after operating the heat exchange ventilator 1, and calculates and stores the total amount of water Msi:rr present in the heat exchange ventilator 1 (step S20). In one example, the total amount of water Msi:rr is obtained by integrating the amount of water M accumulated in the product for each calculation target time t used in the calculation of the amount of dew condensation water M,. Alternatively, the total amount of water M1 is obtained by integrating the amounts of generated water Mtn each of which is generated during the corresponding previous calculation target time t after operating the heat exchange ventilator 1. Alternatively, the total amount of water MSL:Iu is obtained by adding the amount of water M remaining in the drain pan 18 in the calculation target time t obtained in step 319 to the stored previous total amount of water M w, [0046] Next, the control circuit unit 30 determines whether the total amount of water Msijri is higher than a predetermined threshold which is a reference value for determining the possibility of overflow (step S21). When the total amount of water PLL[ITl is higher than the threshold (Yes in step S21), operating the blowers 12 in the current state can result in overflow of water from the drain pan 18. Therefore, the control circuit unit 30 determines whether the blowers 12 are operating with the minimum air volume (step 322). In response to determining that the blowers 12 are not operating with the minimum air volume (No in step 322), the control circuit unit 30 switches to the operation for reducing the amount of generated water (step S23). In one example, the control circuit unit 30 can reduce the amount of dew condensation water M, generated through sensible heat exchange by reducing the air volume from the immediately preceding state of the air volume. In addition, because the air volume is reduced based on the total amount of water M -S LIM accumulated in the actual drain pan 18, the operation time is expected to be extended as compared with the case where the air volume is uniformly lowered based on the air conditions. ?he extension of the operation time is expected to provide comfort and energy saving due to the continuation of heat exchange ventilation operation. Note that the threshold for reducing the air volume only needs to be determined from the capacity of the drain pan 18 installed.

[0047] Note that step S23 involves lowering only the air volume on the exhaust air EA side where water is generated if it is desired to reduce only the amount of generated water Mir, and lowering both the supply air volume and the exhaust air volume if priority is given to a balance of the indoor air volume associated with ventilation. 7n addition, a plurality of thresholds for switching the air volume may be provided. In one example, a plurality of thresholds may be provided so that the control circuit unit 30 can reduce the air volume of the blowers 12 in stepwise, or a threshold for reducing the air volume may be set as the threshold for suspending the blowers 12.

[0048] Thereafter, the control circuit unit 30 determines whether an operation command including the end of the operation of the heat exchange ventilator 1 has been received from the remote 20 (step S27). In response to determining that an operation command including the end of the operation of the heat exchange ventilator 1 has not been received from the remote 20 (No in step S27), the process returns to step 514. Thereafter, when the total amount of water M remains higher than the threshold in step 521, the control circuit unit 30 reduces the air volume of the blowers 12. The control circuit unit 30 can reduce the air volume until it reaches the minimum air volume.

[0049] In response to determining in step 522 that the blowers 12 are operating with the minimum air volume (Yes in step S22), the control circuit unit 30 determines whether the operation with the minimum air volume has continued for a predetermined period (step S24). In response to determining that the operation with the minimum air volume has not continued for the predetermined period (No in step S24), the process transitions to step S27.

[0050] On the other hand, in response to determining that the operation with the minimum air volume has continued for the predetermined period (Yes in step S24), the control circuit unit 30 temporarily stops the operation of the blowers 12, stops the generation of dew condensation water, and drains water from the drain pan 18 (step 525). After the draining of water from the drain pan 18 is completed, the control circuit unit 30 restarts the operation of the blowers 12 (step S26). Although FIG. 7 describes the case where the operation of the blowers 12 is temporarily stopped after a predetermined period of continuous operation with the minimum air volume, the operation of the blowers 12 may be temporarily stopped after a continuance of the state in which the total amount of water M.,, exceeds the threshold, instead of the state with the minimum air volume of the blowers 12.

[0051] The suspension time can be determined from the drain time obtained from the amount of water 1,46,1: discharged from the drain pan 18 and the capacity of the drain pan 18. Because deterioration of comfort due to suspension of ventilation can be minimized with a short suspension time, it is appropriate to keep the suspension time to about five minutes. In addition, the blowers 12 to be stopped in step 525 may be the exhaust blower 12E alone so as to reduce generation of dew condensation water, but the exhaust blower 12E and the supply blower 12S may be simultaneously stopped in order not to lose the balance between the supply air SA and the exhaust air EA in the building. ?hereafter, the process proceeds to step 527.

[0052] On the other hand, in response to determining in step 521 that the total amount of water M,, is equal to or less than the threshold (No in step 521), the control circuit unit 30 increases the air volume of the blowers 12 from the immediately preceding state of the air volume (step S28). In the presence of a plurality of thresholds for switching the air volume, the control circuit unit 30 may raise the air volume in stages. In addition, a threshold for returning the air volume to the state before protective operation, which is an operation for reducing the amount of generated water, may be separately provided. Thereafter, the process returns to step 314.

[0053] In response to determining in step 527 that an operation command including the end of the operation of the heat exchange ventilator 1 has been received from the remote 20 (Yes in step 327), the process ends.

[0054] The above description refers to the method of reducing dew condensation water in winter; however, it is possible to similarly perform heat exchange ventilation while achieving higher energy saving performance than before without causing overflow of dew condensation water from the drain pan 18, also in summer during which dew condensation water is generated from the supply air SA side. In this case, the control circuit unit 30 calculates the absolute humidity at dew point temperature of the supply air (SA), from the absolute humidity of the supply air SA and the dew point temperature. In addition, the control circuit unit 30 calculates the amount of dew condensation water M, per unit time generated by heat exchange from the absolute humidity of the supply air SA, the absolute humidity at the SA dew point temperature, and the supply air volume of the supply blower 125, and further calculates the amount of generated water Mir from the amount of dew condensation water M, per unit time. Then, as in the procedure illustrated in FIG. 6, water may be drained from the drain pan 18 by changing the air volume of the supply blower 12S and temporarily suspending the supply blower 125.

[0055] The above description refers to the method of controlling the air volume of the blowers 12 in the heat exchanger 13 that is a sensible heat exchanger. However, this method is also useful for the heat exchanger 13 that is a total heat exchanger when used under air conditions that can cause dew condensation water. When the heat exchanger 13 is a total heat exchanger, the spacing member 132 is made of a material having gas shielding property and moisture permeability. In this case, in the sheet material 131, sensible heat exchange and latent heat exchange are performed between the exhaust air flow EF passing through the primary air passage 133a and the supply air flow SF passing through the secondary air passage 133b without mixing the exhaust air flow EF and the supply air flow SF.

[0056] As described above, in the heat exchange ventilator 1 according to the first embodiment, the control circuit unit 30 calculates the total amount of water generated by dew condensation during the operation of the heat exchange ventilator 1 from the OA temperature measurement value, the OA relative humidity measurement value, the RA temperature measurement value, the RA relative humidity measurement value, the heat exchange efficiency, the operating air volume, and the threshold information. When the total amount of water is larger than a predetermined threshold, the control circuit unit 30 temporarily lowers at least the air volume of the exhaust blower 12E. This makes it possible to reduce dew condensation water from being generated by heat exchange while the ventilation operation is continued, and to prevent overflow from the drain pan 18. The timing of reducing the air volume can be set to the time point when the water generated by dew condensation reaches a predetermined proportion of the capacity of the drain pan 18 determined by the threshold information. This time point is generally later than the time point when the air volume of the blowers 12 is reduced based on the air conditions. Therefore, the operation time is expected to be extended as compared with the case where the air volume of the blowers 12 is uniformly reduced based on the air conditions. The extension of the operation time is expected to provide comfort and energy saving due to the continuation of heat exchange ventilation operation. This brings about the effect of performing ventilation while achieving energy saving performance higher than before without causing overflow of water from the drain pan 18 in a situation where dew condensation water is constantly generated from the heat exchanger 13.

[0057] Second Embodiment.

FIG. 8 is a diagram schematically illustrating an exemplary configuration of a heat exchange ventilator 25 according to the second embodiment. The heat exchange ventilator 1 is configured to be capable of acquiring detection results from a CO_ sensor 41 disposed in a ventilation space which is a space such as a room in which the heat exchange ventilator 1 is installed. Hereinafter, an example in which the ventilation space is an indoor space 50 will be described. In this example, the control circuit unit 30 of the heat exchange ventilator 1 is*connected to the CO_ sensor 41 via a communication line 42.

The CO2 sensor 41 is a sensor capable of detecting the CO concentration in the indoor space 50. The CO_ sensor 41 transmits the detection results of the CO2 concentration to the control circuit unit 30 of the heat exchange ventilator 1 at predetermined time intervals. Note that the heat exchange ventilator 1 may include the CO, sensor 41. Alternatively, another device such as an air conditioner or an air cleaner disposed in the indoor space 50 in which the heat exchange ventilator 1 is installed and equipped with the CO_ sensor 41, may be communicably connected to the control circuit unit 30 of the heat exchange ventilator 1, and this device may transmit detection results from the CO2 sensor 41 to the control circuit unit 30 of the heat exchange ventilator 1. The CO-sensor 41 is connected to the heat exchange ventilator 1 via the communication line 42, and the communication line 42 may be wired or wireless.

[0058] The heat exchange ventilator 1 has a configuration similar to that described in the first embodiment. However, the control circuit unit 30 controls 20 the air volume of the blowers 12 in cooperation with the CO? sensor 41. Generally, the control circuit unit 30 receives the COz concentration in the indoor space 50 from the 002 sensor 41, sets the air volume of the blowers 12 to be high when the CO2 concentration in the indoor space 50 is higher than a predetermined reference value, and sets the air volume of the blowers 12 to be low when the CO concentration is lower than the predetermined reference value. When the CO: concentration is equal to the predetermined reference value, the air volume of the blowers 12 may be set to be either high or low. During the operation in which the air volume is reduced in order to reduce the total amount of water generated in the heat exchange ventilator 1, the control circuit unit 30 compares the air volume required to reduce the total amount of water with the air volume required to reduce the CO_ concentration, and controls the blowers 12 according to the condition that requires a lower air volume.

[0059] FIG. 9 is a diagram illustrating an example of the relationship between the total amount of water and the corresponding air volume required in the heat exchange ventilator according to the second embodiment. In this diagram, the horizontal axis represents the total amount of water M, in the heat exchange ventilator 1, and the vertical axis represents the required air volume Ql, which is the air volume required for the blowers 12. As illustrated in FIG. 9, the blowers 12 are controlled such that the required air volume Q1 is maximized when the total amount of water M,, is equal to or less than al, the required air volume Ql decreases as the total amount of water M" increases from al, and the required air volume Ql is minimized when the total amount of water M,m, is equal to or larger than a2. The required air volume Ql corresponds to a first required air volume.

[0060] FIG. 10 is a diagram illustrating an example of the relationship between the CO_ concentration in the indoor space and the corresponding air volume required in the heat exchange ventilator according to the second embodiment. In this diagram, the horizontal axis represents the CO_ concentration in the indoor space 50, and the vertical axis represents the required air volume Q2, which is the air volume required for the blowers 12. As illustrated in FIG. 10, the blowers 12 are controlled such that the required air volume Q2 is maximized when the CO2 concentration is equal to or higher than b2, the required air volume Q2 decreases as the CO concentration decreases from b2, and the required air volume Q2 is minimized when the CO, concentration is equal to or lower than bl. The required air volume Q2 corresponds to a second required air volume.

[0061] After calculating the total amount of water M., the control circuit unit 30 calculates the required air volume Ql corresponding to the total amount of water M"-Upon acquiring the CO-concentration from the CO-sensor 41, the control circuit unit 30 calculates the required air volume Q2 for keeping the CO, concentration in the indoor space 50 at a predetermined value, from the information indicating the relationship between the CO, concentration in the indoor space 50 and the required air volume Q2 illustrated in FIG. 10. The control circuit unit 30 compares the required air volume Q1 corresponding to the total amount of water Msi>rt> and the required air volume Q2 corresponding to the CO, concentration in the indoor space 50.

[0062] When the required air volume Q1 corresponding to the total amount of water M>1>> is larger than the required air volume Q2 corresponding to the CO_ concentration in the indoor space 50, it is possible to both reduce generation of dew condensation water and maintain the CO_ concentration even with the air volume of the blowers 12 reduced to Q2. Therefore, the control circuit unit 30 sets the air volume of the blowers 12 to Q2. In this case, because the air volume is smaller than the required air volume Ql, the power consumption of the blowers 12 can be reduced as compared with the case where the CO2 concentration in the indoor space 50 is not considered.

[0063] When the required air volume Q1 corresponding to the total amount of water m is smaller than the required air volume Q2 corresponding to the CO concentration in the indoor space 50, the control circuit unit 30 sets the air volume of the blowers 12 to Q1 and continues the operation in order to prevent occurrence of overflow of the drain pan 18 due to dew condensation water rather than maintaining the 00/ concentration.

[0064] When the required air volume Q1 corresponding to the total amount of water Ms. is equal to the required air volume Q2 corresponding to the CO2 concentration in the indoor space 50, the control circuit unit 30 sets the air volume of the blowers 12 to Ql, that is, Q2.

[0065] Next, a control algorithm will be described in which the control circuit unit 30 performs heat exchange ventilation that reduces the CO_ concentration in the indoor space 50 without causing overflow of dew condensation water from the drain pan 18. FIG. 11 is a flowchart illustrating an example of a procedure for control processing of the heat exchange ventilator according to the second embodiment. Note that steps Sll to S20 are similar to those in FIG. 6 of the first embodiment, and thus the drawing and description thereof will be omitted.

[0066] After calculating and storing the total amount of water N1 present in the heat exchange ventilator 1 in step 320 of FIG. 6, the control circuit unit 30 calculates the required air volume Ql for reducing dew condensation obtained from the total amount of water M. (step S51).

Next, the control circuit unit 30 acquires the 001 concentration in the indoor space 50 from the CO_ sensor 41 (step S52). The control circuit unit 30 calculates the required air volume Q2 for keeping the 00/ concentration in the indoor space 50 comfortable from the acquired CO, concentration (step S53). Thereafter, the control circuit unit 30 compares the required air volume Q1 for reducing dew condensation with the required air volume Q2 for keeping the CO concentration in the indoor space 50 comfortable, and determines whether the required air volume Ql is larger than the required air volume Q2 (step 554).

[0067] When the required air volume Q1 is larger than the required air volume Q2 (Yes in step S54), it is possible to both reduce generation of dew condensation water and maintain the CO2 concentration even with the air volume reduced to Q2, and thus the heat exchange ventilator 1 can reduce the air volume to Q2. Therefore, the control circuit unit 30 controls the air volume of the blowers 12 to Q2 (step S55). Thereafter, the process returns to step 514.

[0068] In response to determining that the required air volume Q1 is equal to or less than the required air volume 0)2 (No in step S54), the control circuit unit 30 determines whether the blowers 12 are operating with the minimum air volume (step S56). In response to determining that the blowers 12 are not operating with the minimum air volume (No in step S56), the control circuit unit 30 controls the air volume of the blowers 12 to Ql in order to prioritize the prevention of overflow of the drain pan 18 due to dew condensation water over the CO, concentration (step S57). When the total amount of water due to generation of dew condensation water in the heat exchange ventilator 1 reduces, the required air volume Q1 increases. Once the required air volume Ql becomes larger than the required air volume 0)2, it is possible to return to the energy saving operation in which the 002 concentration is prioritized.

[0069] Thereafter, the process transitions to step 827 described with reference to FIG. 7 in the first embodiment. That is, the control circuit unit 30 determines whether an operation command including the end of the operation of the heat exchange ventilator 1 has been received from the remote 20, and in response to determining that an operation command including the end of the operation of the heat exchange ventilator 1 has not been received from the remote 20, the process returns to step S14. Thereafter, when the required air volume Ql remains equal to or less than the required air volume Q2 in step S53 and the required air volume Ql keeps decreasing, the control circuit unit 30 reduces the air volume of the blowers 12 in step S57. Then, the air volume can be reduced until the required air volume Ql reaches the minimum air volume.

[0070] In response to determining in step S56 that the blowers 12 are operating with the minimum air volume (Yes in step S56), that is, the required air volume Ql is the minimum air volume of the blowers 12, the control circuit unit 30 causes the process to transition to step 524 described with reference to FIG. 7 in the first embodiment. Step 524 and the subsequent steps are similar to those described in the first embodiment, and thus the description thereof will be omitted.

[0071] The above description refers to the method of controlling the air volume using the CO-concentration in the indoor space 50 measured using the CO_ sensor 41, but the air volume may be controlled using the result of measurement of air quality, i.e. properties of the air in the indoor space 50. As the air quality, not only CO2 but also dust, an odor substance, a chemical substance emitted from a building, and the like can be measured. The odor substance is a substance emitted from a human body, for example, ammonia, hydrogen sulfide, or methyl mercaptan.

In this case, in FIG. 8, instead of the CO2 sensor 41, an air quality detection unit capable of detecting a substance to be removed from the indoor space 50 is provided. Then, in step 553 of FIG. 11, the required air volume Q2 is calculated so that the concentration of the target substance detected by the air quality detection unit becomes a concentration for keeping the indoor space 50 comfortable.

[0072] In the heat exchange ventilator 1 according to the second embodiment, the control circuit unit 30 calculates the required air volume Ql for reducing dew condensation, from the total amount of water that is calculated from the OA temperature measurement value, the OA relative humidity measurement value, the RA temperature measurement value, the RA relative humidity measurement value, the heat exchange efficiency, the operating air volume, and the threshold information. Then, the control circuit unit 30 calculates, from the result of measurement of the air quality, the required air volume Q2 that makes the concentration of the air quality in the indoor space 50 smaller than a predetermined reference value. When the required air volume Q2 is smaller than the required air volume Ql, the control circuit unit 30 controls the air volume of the blowers 12 to Q2. This makes it possible to both reduce generation of dew condensation water and maintain the air quality. In this case, because the air volume is smaller than the required air volume Ql, the power consumption of the blowers 12 can be reduced as compared with the case of the first embodiment where the air quality in the indoor space 50 is not considered. When the required air volume Ql is smaller than the required air volume Q2, the air volume of the blowers 12 is controlled to Ql. This makes it possible to prevent occurrence of overflow of the drain pan 18 due to dew condensation water rather than maintaining the 002 concentration.

[0073] In the above description, the RA temperature sensor 16 and the RA humidity sensor 17 are provided on the windward of the heat exchanger 13 in the exhaust air passage 116, that is, in the windward exhaust air passage 116a. However, the RA temperature sensor 16 and the RA humidity sensor 17 may be disposed at any positions where the temperature and humidity of the exhaust air flow FP' can be detected. In one example, the RA temperature sensor 16 and the RA humidity sensor 17 may be provided on the leeward of the heat exchanger 13 in the exhaust air passage 116, that is, in the leeward exhaust air passage 116b.

Similarly, the OA temperature sensor 14 and the OA humidity sensor 15 may be disposed at any positions where the temperature and humidity of the supply air flow SF can be detected, instead of being provided on the windward of the heat exchanger 13 in the supply air passage 115, that is, in the windward supply air passage 115a. In one example, the OA temperature sensor 14 and the OA humidity sensor 15 may be provided on the leeward of the heat exchanger 13 in the supply air passage 115, that is, in the leeward supply air passage 115b.

[0074] The control circuit unit 30 is implemented as processing circuitry. The processing circuitry may be dedicated hardware, an integrated circuit, or a circuit including a processor. FIG. 12 is a block diagram illustrating an exemplary hardware configuration of the control unit of the heat exchange ventilator according to the first and second embodiments. The control circuit unit 30 includes a processor 501 and a memory 502. The processor 501 is a central processing unit (CPU, also referred to as a central processing device, a processing device, a computation device, a microprocessor, a microcomputer, or a digital signal processor (DSP)), a system large scale integration (LSI), or the like. The memory 502 is a non-volatile or volatile semiconductor memory, a magnetic disk, a flexible disk, an optical disc, a compact disc, a mini disc, a digital versatile disk (DVD), or the like. Examples of the non-volatile or volatile semiconductor memory include a random access memory (RAM), a read only memory (ROM), a flash memory, an erasable programmable read only memory (EPROM), an electrically erasable programmable read only memory (EEPROM) (registered trademark), and the like. The processor 501 and the memory 502 are connected via a bus line 503.

[0075] The control circuit unit 30 is implemented by reading a program from the memory 502 and executing the program by the processor 501. The program describes the procedure for controlling the air volume of the supply blower 125 and the exhaust blower 12E on the basis of the detection results from the OA temperature sensor 14, the OA humidity sensor 15, the RA temperature sensor 16, and the RA humidity sensor 17 or on the basis of the detection results from the air quality detection unit in addition to these. A plurality of processors and a plurality of memories may cooperate to implement the above functions. Some of the functions of the control circuit unit 30 may be embodied as an electronic circuit which is dedicated hardware, and the other functions may be implemented using the processor 501 and the memory 502. In one example, the control circuit unit 30 controls the operations of the supply blower 125 and the exhaust blower 12E using electric signals.

[0076] The configurations described in the above-mentioned embodiments indicate examples. The embodiments can be combined with another well-known technique and with each other, and some of the configurations can be omitted or changed in a range not departing from the gist.

Reference Signs List [0077] 1 heat exchange ventilator; 11 body casing; 12 blower; 12E exhaust blower; 12S supply blower; 13 heat 5 exchanger; 14 OA temperature sensor; 15 OA humidity sensor; 16 RA temperature sensor; 17 RA humidity sensor; 18 drain pan; 19 air passage switching damper; 20 remote; 30 control circuit unit; 41 CO_ sensor; 42 communication line; 50 indoor space; 60 dew condensation water; 111 outdoor air inlet; 112 exhaust air outlet; 113 supply air outlet; 114 indoor air inlet; 115 supply air passage; 115a windward supply air passage; 115b leeward supply air passage; 116 exhaust air passage; 116a windward exhaust air passage; 116b leeward exhaust air passage; 116c bypass air passage; 131 sheet material; 132 spacing member; 132a spacing member; 132b spacing member; 133a primary air passage; 133b secondary air passage; 181 drain port; EA exhaust air; EF exhaust air flow; OA outdoor air; Q1 required air volume; Q2 required air volume; RA return air; SA supply air; SF supply air flow.

Claims

CLAIMS1. A heat exchange ventilator comprising: a supply blower; an exhaust blower; a casing including a supply air passage through which a supply air flow from an outdoor space to an indoor space formed by the supply blower passes, and an exhaust air passage through which an exhaust air flow from an indoor space to an outdoor space formed by the exhaust blower passes; a heat exchanger installed between the supply air passage and the exhaust air passage, and configured to exchange heat between the supply air flow and the exhaust air flow; a drain pan to hold and drain water generated by dew condensation in the heat exchanger; a supply air flow temperature sensor to detect temperature of the supply air flow; a supply air flow humidity sensor to detect humidity 20 of the supply air flow; an exhaust air flow temperature sensor to detect temperature of the exhaust air flow; an exhaust air flow humidity sensor to detect humidity of the exhaust air flow; and a control unit to control the supply blower and/or the exhaust blower based on a total amount of water generated by dew condensation in the heat exchanger and present in the drain pan, the total amount of water being calculated based on the temperature and the humidity of the supply air flow and the temperature and the humidity of the exhaust air flow.
2. The heat exchange ventilator according to claim 1, wherein the control unit reduces air volume of the exhaust blower and/or the supply blower when the total amount of water calculated is higher than a predetermined threshold.
3. The heat exchange ventilator according to claim 1 or 2, wherein the control unit increases air volume of the supply blower and/or the exhaust blower when the total amount of water calculated is equal to or lower than a predetermined threshold.
4. The heat exchange ventilator according to any one of claims 1 to 3, wherein the control unit stops the supply blower and/or the exhaust blower when the total amount of water calculated remains higher than a predetermined threshold for a predetermined time.
5. The heat exchange ventilator according to any one of claims 1 to 4, wherein the control unit calculates the total amount of water using a difference between an amount of water generated by the dew condensation and an amount of drainage from the drain pan, the amount of water being calculated using the temperature of the supply air flow detected by the supply air flow temperature sensor, the humidity of the supply air flow detected by the supply air flow humidity sensor, the temperature of the exhaust air flow detected by the exhaust air flow temperature sensor, and the humidity of the exhaust air flow detected by the exhaust air flow humidity sensor.
6. The heat exchange ventilator according to any one of claims 1 to 5, wherein the control unit receives a detection result of an air quality of a space in which the heat exchange ventilator is disposed, compares a first required air volume that is an air volume required to reduce the dew condensation from the total amount of water calculated from the temperature and the humidity of the supply air flow and the temperature and the humidity of the 5 exhaust air flow with a second required air volume that is an air volume required to make the air quality smaller than a predetermined reference value from the detection result of the air quality, and switches the supply blower and/or the exhaust blower to a smaller one of the required air 10 volumes.
7. The heat exchange ventilator according to claim 6, wherein the air quality is any of CO2, dust, an odor substance, and a chemical substance emitted from a building.
8. The heat exchange ventilator according to any one of claims 1 to 7, wherein the supply air flow temperature sensor and the supply air flow humidity sensor are provided on windward of the heat exchanger in the supply air passage.
9. The heat exchange ventilator according to any one of claims 1 to 8, wherein the exhaust air flow temperature sensor and the exhaust air flow humidity sensor are provided on windward of the heat exchanger in the exhaust air passage.
10. The heat exchange ventilator according to any one of claims 1 to 8, wherein the exhaust air flow temperature sensor and the exhaust air flow humidity sensor are provided on leeward of the heat exchanger in the exhaust air passage.