Temperature control system of agricultural greenhouse

Abstract

To simultaneously use absorbed heat and exhaust heat of a heat pump device for air-conditioning of two greenhouses to increase efficiency of the heat pump device.SOLUTION: A temperature control system controls internal temperatures of agricultural greenhouses 100, 200 cultivating field crops by a heat pump device 30. In the temperature control system, a first heat exchanger 31 and a second heat exchanger 31 are connected to a heat pump device body having a compressor and an expansion valve, the first heat exchanger 31 is provided in the first greenhouse 100 and the second heat exchanger 31 is provided in the second greenhouse 200, and the first greenhouse 100 and the second greenhouse 200 are alternately low-temperature controlled and high-temperature controlled by an operation of the heat pump device 30.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a temperature control system for an agricultural greenhouse. [Background technology]

[0002] Conventionally, a known temperature control system for an agricultural greenhouse is the temperature control system described in Patent Document 1. This temperature control system uses a heat pump device or a heater, and aims to provide an optimal growing environment for agricultural crops based on the detection results of temperature and humidity sensors inside the greenhouse. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6686492 DISCLOSURE OF THEINVENTION [Problem to be solved by the invention]

[0004] However, the technology of Patent Document 1 only uses either the heat absorption or exhaust heat of the heat pump device for cooling or heating, so there is room for improvement in the efficiency of the heat pump device.

[0005] The present invention has been made in consideration of the above circumstances, and has an object to increase the efficiency of a heat pump device by simultaneously using the heat absorption and exhaust heat of the heat pump device for cooling and heating two rooms in a house. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, the temperature control system for an agricultural greenhouse of the present invention is a temperature control system that controls the temperature inside an agricultural greenhouse for cultivating agricultural crops using a heat pump device, and is characterized in that a first heat exchanger and a second heat exchanger are connected to a heat pump device main body having a compressor and an expansion valve, the first heat exchanger is disposed in the first house and the second heat exchanger is disposed in the second house, and the first house and the second house are alternately controlled to low and high temperatures by operation of the heat pump device. Effect of the Invention

[0007] The efficiency of heating and cooling can be improved by simultaneously using the heat absorption and exhaust heat of the heat pump device to cool and heat two rooms in the house. [Brief description of the drawings]

[0008] [Figure 1] 1 is a schematic diagram of a temperature control system for an agricultural greenhouse according to an embodiment of the present invention. [Diagram 2] FIG. 13 is a diagram showing an example of control of culture medium temperature. [Figure 3A] FIG. 13 is a schematic diagram showing the airflow inside the cabinet when the ventilation fan is operating at full capacity. [Figure 3B] FIG. 13 is a schematic diagram showing the airflow inside the cabinet when the ventilation fan half is in operation. [Figure 4] 11 is a flowchart showing temperature control of two rooms in a house by the heat pump device. [Diagram 5] 1 is a flowchart for controlling the medium temperature within a high temperature compatible range. [Figure 6] 1 is a flowchart for controlling the medium temperature within a low temperature compatible range. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 shows an outline of a temperature control system that simultaneously controls two Shiitake mushroom cultivation houses (house 1_100, house 2_200) as agricultural houses. This temperature control system applies temperature stimulation (high temperature stimulation and low temperature stimulation) to the medium 20 in the house 100 to promote the growth of mycelium.

[0010] A plurality of rows of shelves 10 are arranged inside each of the houses 100 and 200. A plurality of Shiitake mushroom culture media 20 are mounted on the shelves 10.

[0011] Culture medium temperature sensors TH3a and TH3b are disposed in the shiitake mushroom culture medium 20. The culture medium temperature sensors TH3a and TH3b are connected to a controller 70 as a control unit by wire or wirelessly (BLUETOOTH, registered trademark). The culture medium temperature sensors TH3a and TH3b may be disposed in all the culture media 20, or may be disposed in one or some of the culture media 20 located near the center of the chamber.

[0012] If it is difficult to place the culture medium temperature sensors TH3a and TH3b, the measured value of the chamber temperature sensor TH1 can be simply substituted (additively or substractively corrected) as the culture medium internal temperature. In other words, it has been found that there is a temperature difference of ±2 to 3°C between the culture medium internal temperature TH3a and the chamber temperature TH1 during the temperature drop and temperature rise periods, as shown by the four vertical double-headed arrows in Figure 2.

[0013] Therefore, during the temperature decreasing period on the left side of Fig. 2, the internal medium temperature can be simply calculated by adding the internal medium temperature TH3a = internal temperature TH1 + 2 to 3°C. Also, during the temperature increasing period on the right side of Fig. 2, the internal medium temperature can be simply calculated by subtracting the internal medium temperature TH3a = internal temperature TH1 - 2 to 3°C.

[0014] A plurality of mist nozzles 80 are disposed above the shelf 10. These mist nozzles 80 spray fine water droplets in a mist onto the culture medium 20, providing appropriate humidity and water spray cooling.

[0015] A heat pump device 30 and a boiler 40 are disposed outside the houses 100 and 200. The heat pump device 30 has a compressor and an expansion valve, and one heat pump device 30 is shared by the two houses 100 and 200.

[0016] This heat pump device 30 is connected to multiple air heat exchangers 31 inside the storage unit. The air heat exchanger 31 in one house is the first heat exchanger, and the air heat exchanger 31 in the other house is the second heat exchanger. The boiler 40 is connected to a hot air duct 41 inside the storage unit.

[0017] An exhaust fan 50 is provided on one side wall of each of the houses 100 and 200. An intake damper 60 is provided on the other side wall of each of the houses 100 and 200.

[0018] An inside-compartment temperature sensor TH1 is disposed substantially in the center of the compartment. An outside-compartment temperature sensor TH2 is disposed on the inlet side of the intake damper 60.

[0019] 2 shows an example in which the temperature in the houses 100 and 200 is controlled by the controller 70 based on the temperatures measured by the temperature sensors TH1, TH2, TH3a and TH3b. The vertical axis of FIG. 2 represents temperature, and the horizontal axis represents time.

[0020] Temperature control was performed continuously for 24 hours from 12:36 on March 1, 2023 to 12:36 the next day (March 2, 2023). The first was high temperature control (first half) in which the internal temperature of the medium TH3a was controlled at around 20°C. This high temperature control (first half) continued for 6 hours.

[0021] During the first half of high temperature control (first half), the inside temperature TH1 was around 20°C (±3°C) and the outside temperature TH2 was 14°C, but as the end of high temperature control (first half) approached, the inside temperature TH1 and the outside temperature TH2 began to drop. This is due to the influence of sunset. Strong heating is used during the first half of high temperature control (first half) (until 16:00), but weak heating is used in the second half (after 16:00) in preparation for low temperature control.

[0022] 3A and 3B, the ventilation fan 50 is operated and the intake damper 60 is opened. Heating by the heat pump device 30 (heapon heating) is also performed.

[0023] The set temperature of the heat pump unit 30 can be set to 20° C. By actively introducing outside air into the storage unit in this manner, energy saving of the heat pump unit 30 can be achieved.

[0024] In the weak heating mode, the ventilation fan 50 is stopped and the intake damper 60 is closed. Also, weak heating is performed by the heat pump device 30.

[0025] In the weak heating mode, the set temperature of the heat pump device 30 can be temporarily set to, for example, 5° C. This allows the medium internal temperature TH3a to be quickly achieved at approximately 10° C. After the medium internal temperature TH3a reaches approximately 10° C., the set temperature of the heat pump device 30 can be returned from 5° C. to 10° C.

[0026] After the high temperature control (first half), low temperature control will be implemented. This low temperature control will continue for 12 hours until sunrise the next day (March 2nd).

[0027] In this low-temperature control, the set temperature of the heat pump device 30 is maintained at 10° C. (low heating), and the culture medium temperature is controlled to around 10° C. In the latter half of the low-temperature control, the outside temperature TH2 drops to about 5° C., but the inside temperature TH1 remains relatively stable at about 8° C. even with "no heating or cooling." Therefore, energy savings in the heat pump device 30 can be achieved.

[0028] Immediately after sunrise (6:36), the inside temperature TH1 and the outside temperature TH2 rise sharply. The temperature inside the medium TH3a also rises, but the rate of increase is slow.

[0029] Therefore, strong heating is performed to bring the culture medium internal temperature TH3a to the high temperature control (second half) as quickly as possible. In this strong heating, the ventilation fan 50 is operated and the intake damper 60 is opened as shown in Figures 3A and 3B.

[0030] Heating (hea-pump heating) is also performed by the heat pump device 30. By actively introducing outside air into the refrigerator in this manner, it is possible to quickly transition to high temperature control (later half), and energy saving of the heat pump device 30 can also be achieved.

[0031] The operation of the ventilation fans 50 can be selected from either full operation, in which two ventilation fans 50 are operated and two intake dampers 60 are fully opened as shown in Fig. 3A, or half operation, in which only one ventilation fan 50 is operated and only one intake damper 60 is fully opened as shown in Fig. 3B. When the temperature TH3a inside the medium approaches around 20°C (suitable high temperature range), it is possible to switch from full operation to half operation.

[0032] Continuous full or half operation causes strong air to hit a specific part of the culture medium 20 (the part of the culture medium 20 near the intake damper 60) for a long period of time. This causes a sudden drop in humidity in the culture medium 20, adversely affecting the growth of the shiitake mushrooms. Therefore, it is desirable to limit the continuous time of full or half operation to within a specified time, or to limit the opening of the intake damper 60 continuously or intermittently.

[0033] In the case of half operation, it is desirable to alternate the airflow inside the chamber between diagonal airflow 1 and diagonal airflow 2 at predetermined intervals, as shown by the solid and dashed arrows in Figure 3B. This makes it possible to prevent strong air from hitting a particular culture medium 20 for a long period of time, and also makes it possible to make the temperature distribution inside the chamber uniform.

[0034] It is preferable to dispose the inside temperature sensor TH1, the air conditioner sensor TH1a, and the heating sensor TH1b at the intersection of the diagonal air current 1 and the diagonal air current 2. This allows the temperature inside the cabinet to be measured accurately.

[0035] ●Dual temperature control The temperature control system of the present application is characterized by simultaneously controlling the temperature of the two houses 100, 200 using a common heat pump device 30 (dual temperature control). In the shiitake mushroom cultivation houses 100, 200, high and low temperature control are repeated to provide a temperature stimulus to the mycelium in the medium 20, accelerating mushroom germination and promoting the growth of the fruiting bodies that have already germinated.

[0036] Therefore, the heat pump unit 30 transfers thermal energy pumped from one house to the other house, and then transfers thermal energy in the opposite direction after a predetermined time (e.g., 12 hours), repeating high temperature control and low temperature control. The heat pump unit 30 transfers thermal energy pumped from a low temperature heat source to the high temperature side, and can realize heating and cooling of the houses 100 and 200 with higher efficiency (energy saving) than ordinary heating and cooling devices.

[0037] 4 is a flowchart showing high temperature control and low temperature control of two houses 100, 200 (houses 1 and 2) by the heat pump unit 30. When the heat pump unit 30 is turned ON in step S41, high temperature control of house 1 (step S42) and low temperature control of house 2 (step S44) start.

[0038] The high temperature control of the house 1 is performed as shown in the flowchart of Fig. 5 (step S43). The low temperature control of the house 2 is performed as shown in the flowchart of Fig. 6 (step S45).

[0039] When, for example, 12 hours have passed since the start of the high temperature control of house 1 and the low temperature control of house 2 (step S46), the heat pump unit 30 switches between heating and cooling (step S47). That is, the low temperature control of house 1 and the high temperature control of house 2 are now performed (steps S48, S50).

[0040] The low temperature control of the house 1 is performed as shown in the flowchart of Fig. 6 (step S49). The high temperature control of the house 2 is performed as shown in the flowchart of Fig. 5 (step S51).

[0041] When 12 hours have elapsed since the start of the low-temperature control of House 1 and the high-temperature control of House 2, the heat pump device 30, the boiler 40, the exhaust fan 50, etc. are stopped. This completes one cycle of low-temperature control and high-temperature control. If the next cycle is to be started without stopping the temperature control, steps S41 to S53 are repeated.

[0042] In the above embodiment, one cycle of high-temperature control and low-temperature control is set to 12 hours + 12 hours = 24 hours. However, the time of one cycle can be appropriately changed depending on the region, season, etc. For example, in winter when the night is long, the time of low-temperature control can be made longer than 12 hours and the time of high-temperature control can be made shorter than 12 hours. On the contrary, in summer when the night is short, the time of low-temperature control can be made shorter than 12 hours and the time of high-temperature control can be made longer than 12 hours.

[0043] ● High-temperature control The high-temperature control shown in FIG. 2 of the culture medium 20 and the high-temperature control shown in FIG. 4 can be performed according to the flowchart of FIG. 5. This flowchart shows the control contents of the controller 70 in FIGS. 1, 3A, and 3B.

[0044] The temperatures measured by the culture medium temperature sensors TH3a and TH3b are taken as the internal culture medium temperature TH3a and the surface culture medium temperature TH3b. The culture medium temperature sensor TH3a is arranged inside the culture medium 20, and the culture medium temperature sensor TH3b is arranged on the surface of the culture medium 20. The surface culture medium temperature TH3b is used for monitoring and not for temperature control of high-temperature control and low-temperature control. Note that it is also possible to use the surface culture medium temperature TH3b instead of the internal culture medium temperature TH3a.

[0045] First, it is determined whether the internal culture medium temperature TH3a is within the high-temperature range (17°C < TH3a < 23°C) (step S1). If the internal culture medium temperature TH3a is not within the high-temperature range (17°C < TH3a < 23°C), it is determined whether to raise the internal culture medium temperature TH3a (step S2). If TH3a ≤ 17°C, the process proceeds to step S3. If 23°C ≤ TH3a, the process proceeds to the heat exhaust outside the warehouse (heat pump cooling) in step S11.

[0046] When the temperature is rising and the outside temperature TH2 is α °C or more higher than the internal temperature of the medium TH3a, the exhaust fan is turned on to introduce warm outside air into the storage for energy saving (step S3 ⇒ S4). At this stage, hypone heating or boiler heating is not performed. α °C can be set to any value, but here it is set to α °C = 1 °C (the same applies to Fig. 6).

[0047] The introduction of outside air by the exhaust fan continues until the internal temperature of the medium TH3a reaches the high temperature range (17 °C < TH3a < 23 °C). When the internal temperature of the medium TH3a reaches the high temperature range (17 °C < TH3a < 23 °C), the exhaust fan is stopped (step S7).

[0048] However, if the internal temperature of the medium TH3a does not reach the high temperature range (17 °C < TH3a < 23 °C) even after continuously introducing outside air for 1 hour, the process proceeds from step S5 to step S9, and boiler heating is performed together with the introduction of outside air. Then, when the internal temperature of the medium TH3a reaches the high temperature range (17 °C < TH3a < 23 °C), the exhaust fan and boiler heating are stopped (step S7). The starting point of "1 hour elapsed?" in step S5 is the time of judgment in step S3.

[0049] When the temperature is rising and the outside temperature TH2 is not α °C or more higher than the internal temperature of the medium TH3a, that is, when the outside air temperature cannot be used for heating, the process moves from step S3 ⇒ S9 to perform boiler heating. The exhaust fan is OFF.

[0050] Boiler heating continues until the internal temperature of the medium TH3a reaches the high temperature range (17 °C < TH3a < 23 °C). When the internal temperature of the medium TH3a reaches the high temperature range (17 °C < TH3a < 23 °C), the boiler heating is stopped (step S7).

[0051] When not heating (when cooling), the outside heat of the storage is removed by hypone cooling (step S11). Also, when the outside temperature TH2 is α °C or more lower than the internal temperature of the medium TH3a, the exhaust fan is turned on to introduce cold outside air into the storage for energy saving (step S12 ⇒ S13).

[0052] The introduction of outside air by the exhaust fan continues until the internal temperature TH3a of the medium reaches the high temperature range (17°C < TH3a < 23°C). When the internal temperature TH3a of the medium reaches the high temperature range (17°C < TH3a < 23°C), the exhaust fan is stopped (step S7).

[0053] However, if the internal temperature TH3a of the medium does not reach the high temperature range (17°C < TH3a < 23°C) even after continuously introducing outside air for 1 hour, proceed from step S14 to step S16, and perform water spray cooling by the mist nozzle 80 together with the introduction of outside air. Then, when the internal temperature TH3a of the medium reaches the high temperature range (17°C < TH3a < 23°C), the exhaust fan, hypone cooling, and water spray cooling are stopped (step S7). The starting point of "1 hour elapsed?" in step S14 is the time of judgment in step S12.

[0054] When cooling down and the outside temperature TH2 is not α°C or more lower than the internal temperature TH3a of the medium, that is, when the outside air temperature cannot be used for cooling, move from step S12 ⇒ S16 and perform water spray cooling by the mist nozzle 80. The exhaust fan is OFF.

[0055] The hypone cooling and water spray cooling continue until the internal temperature TH3a of the medium reaches the high temperature range (17°C < TH3a < 23°C). When the internal temperature TH3a of the medium reaches the high temperature range (17°C < TH3a < 23°C), the hypone cooling and water spray cooling are stopped (step S7). The above temperature control is continuously performed unless "temperature control stop" is set in step S8.

[0056] ● Low-temperature control The low-temperature control shown in FIG. 2 and the low-temperature control shown in FIG. 4 of the medium 20 can be performed according to the flowchart of FIG. 6. This flowchart shows the control contents of the controller 70 in FIGS. 1, 3A, and 3B.

[0057] First, it is determined whether the internal temperature TH3a of the medium is in the low temperature range (7°C < TH3a < 13°C) (step S21).

[0058] When the internal temperature TH3a of the medium is not within the low-temperature suitable range, it is determined whether to raise the temperature of the internal temperature TH3a of the medium (step S22). If TH3a ≤ 7°C, the process proceeds to step S23. If 13°C ≤ TH3a, the process proceeds to step S31.

[0059] When raising the temperature and the outside temperature TH2 outside the warehouse is α°C or more higher than the internal temperature TH3a of the medium, turn on the exhaust fan to introduce warm outside air into the warehouse for energy saving (step S23 ⇒ S24). At this stage, hypone heating and boiler heating are not performed yet.

[0060] The introduction of outside air by the exhaust fan continues until the internal temperature TH3a of the medium falls within the low-temperature suitable range (7°C < TH3a < 13°C). When the internal temperature TH3a of the medium falls within the low-temperature suitable range (7°C < TH3a < 13°C), stop the exhaust fan (step S27).

[0061] However, if the internal temperature TH3a of the medium does not reach the low-temperature suitable range (7°C < TH3a < 13°C) even after continuously introducing outside air for 1 hour, proceed from step S25 to step S29 to perform hypone heating together with the introduction of outside air. Then, when the internal temperature TH3a of the medium falls within the low-temperature suitable range (7°C < TH3a < 13°C), stop the exhaust fan and the hypone (step S27). The starting point of "1 hour elapsed?" in step S25 is the time of judgment in step S23.

[0062] When raising the temperature and the outside temperature TH2 outside the warehouse is not α°C or more higher than the internal temperature TH3a of the medium, that is, when the outside air temperature cannot be used for raising the temperature, move from step S23 ⇒ S29 to perform hypone heating. The exhaust fan is OFF.

[0063] Hypone heating continues until the internal temperature TH3a of the medium falls within the low-temperature suitable range (7°C < TH3a < 13°C). When the internal temperature TH3a of the medium falls within the low-temperature suitable range (7°C < TH3a < 13°C), stop the hypone heating (step S27).

[0064] When not heating up (when cooling down) and the outside temperature TH2 is α °C or more lower than the internal temperature of the medium TH3a, turn on the exhaust fan to introduce cold outside air into the storage for energy saving (step S31 ⇒ S32). At this stage, hypone cooling is not yet performed.

[0065] The introduction of outside air by the exhaust fan continues until the internal temperature of the medium TH3a reaches the low temperature range (7 °C < TH3a < 13 °C). When the internal temperature of the medium TH3a reaches the low temperature range (7 °C < TH3a < 13 °C), stop the exhaust fan (step S27).

[0066] However, if the internal temperature of the medium TH3a does not reach the low temperature range (7 °C < TH3a < 13 °C) even after continuously introducing outside air for 1 hour, proceed from step S23 to step S35 to perform hypone cooling together with the introduction of outside air. Then, when the internal temperature of the medium TH3a reaches the low temperature range (7 °C < TH3a < 13 °C), stop the exhaust fan and hypone cooling (step S27). The starting point of "1 hour elapsed?" in step S33 is the time of judgment in step S31.

[0067] When cooling down and the outside temperature TH2 is not α °C or more lower than the internal temperature of the medium TH3a, that is, when the outside air temperature cannot be used for cooling, move to step S31 ⇒ S35 to perform hypone cooling. The exhaust fan is OFF.

[0068] Hypone cooling continues until the internal temperature of the medium TH3a reaches the low temperature range (7 °C < TH3a < 13 °C). When the internal temperature of the medium TH3a reaches the low temperature range (7 °C < TH3a < 13 °C), stop hypone cooling (step S27). The above temperature control is continuously performed unless "temperature control stop" is set in step S28.

[0069] As described above, the present invention has been specifically described based on the embodiments. However, it goes without saying that the present invention is not limited to the above embodiments and can be variously modified within the scope of the technical idea described in the claims.

Explanation of symbols

[0070] 10: Shelf for storing culture medium 20: Culture medium for shiitake mushrooms 30: Heat pump device 31: Air heat exchanger 40: Boiler 41: Hot air duct 50: Exhaust fan (ventilation device) 60: Intake damper (ventilation device) 70: Controller (control unit) 80: Mist nozzle TH1: Internal temperature sensor TH1a: Internal air conditioner sensor TH1b: Internal heating sensor TH2: External temperature sensor TH3a, TH3b: Culture medium temperature sensor 100: Shiitake mushroom cultivation house 1 200: Shiitake mushroom cultivation house 2

Claims

1. A temperature control system that controls the temperature inside an agricultural greenhouse in which agricultural crops are grown by a heat pump device, the temperature control system comprising: A temperature control system comprising: a first heat exchanger and a second heat exchanger connected to a heat pump device main body having a compressor and an expansion valve, the first heat exchanger being disposed in a first house and the second heat exchanger being disposed in a second house, and the first house and the second house being alternately controlled to low temperature and high temperature by operation of the heat pump device.

2. 2. The temperature control system according to claim 1, wherein the low temperature control and the high temperature control of said first house and said second house are switched every half day.

3. The temperature control system according to claim 1 or 2, further comprising: a ventilation device for the first house and the second house; an outside temperature sensor for detecting the outside temperatures of the first house and the second house; a culture medium temperature sensor for detecting the culture medium temperature; and a control unit for controlling the ventilation device and the heat pump device based on the detection results of the outside temperature sensor and the culture medium temperature sensor, wherein the control unit controls the temperature of the culture medium so that the culture medium temperature alternately switches between the high temperature suitable range and the low temperature suitable range after maintaining each of the high temperature suitable range and the low temperature suitable range for a predetermined time. When raising the culture medium temperature, if the temperature detected by the outside temperature sensor is higher than a value obtained by adding a predetermined temperature to the temperature in the high temperature range, the ventilation device is driven for a predetermined time until the culture medium temperature reaches the high temperature range or the low temperature range, and if the culture medium temperature has not reached the high temperature range or the low temperature range even after the predetermined time has elapsed, the heat pump device is driven together with the ventilation device until the culture medium temperature reaches the high temperature range or the low temperature range, and if the temperature detected by the outside temperature sensor is not higher than a value obtained by adding a predetermined temperature to the temperature in the high temperature range, the heat pump device is driven until the culture medium temperature reaches the high temperature range or the low temperature range, When lowering the culture medium temperature, if the temperature detected by the outside temperature sensor is lower than a value obtained by subtracting a predetermined temperature from the temperature in the high temperature range, the ventilation device is driven for a predetermined time until the culture medium temperature reaches the high temperature range or the low temperature range, and if the culture medium temperature has not reached the high temperature range or the low temperature range even after the predetermined time has elapsed, the heat pump device is driven together with the ventilation device until the culture medium temperature reaches the high temperature range or the low temperature range, and if the temperature detected by the outside temperature sensor is not lower than a value obtained by subtracting a predetermined temperature from the temperature in the high temperature range, the heat pump device is driven until the culture medium temperature reaches the high temperature range or the low temperature range. A temperature control system comprising:

4. the first house and the second house are equipped with a boiler device for heating; 4. The temperature control system of claim 3, wherein, when raising the culture medium temperature, if the temperature detected by the external temperature sensor is not higher than a value obtained by adding a predetermined temperature to the temperature in the high temperature suitable range, the heat pump device is driven for a predetermined time until the culture medium temperature reaches the high temperature suitable range or the low temperature suitable range, and, if the culture medium temperature has not reached the high temperature suitable range or the low temperature suitable range even after the predetermined time has elapsed, the boiler device is driven together with the heat pump device until the culture medium temperature reaches the high temperature suitable range or the low temperature suitable range.

Images