WO2012090511A1

WO2012090511A1 - Precise air conditioning device

Info

Publication number: WO2012090511A1
Application number: PCT/JP2011/050173
Authority: WO
Inventors: 克昌藤井
Original assignee: 株式会社朝日工業社
Priority date: 2010-12-28
Filing date: 2011-01-07
Publication date: 2012-07-05
Also published as: JP4712910B1; CN102803858A; KR20120087803A; CN102803858B; TW201226813A; TWI431230B; KR101272088B1; JP2012137271A

Abstract

Provided is a precise air conditioning device which can control the amount of waste heat in response to the air conditioning load of a control target while a constant load of a refrigeration cycle is maintained. The precise air conditioning device of the present invention introduces air in a chamber (12) disposed in a clean room (10) and circulates the air in the chamber (12) at a set temperature, wherein a condenser (31), an expansion valve (35), and an evaporator (26) are sequentially connected from a discharge side to a suction side of a compressor (29). The precise air conditioning device comprises: a refrigeration cycle (25) which includes a hot gas bypass circuit (40) flowing hot gas at the discharge side of the compressor (29) to the evaporator (26); a heat recovery unit (28) which has the evaporator (26) of the refrigeration cycle (25) accommodated therein, and introduces air from the chamber (12) and circulates the air in the chamber (12) by adjusting the air to the set temperature by means of the evaporator (26); and a heat radiating unit (33) which is disposed in the clean room (10) and accommodates the condenser (31) of the refrigeration cycle (25), and includes a variable capacity fan (32) for cooling the condenser (31) with the air in the clean room (10).

Description

Precision air conditioner

The present invention relates to a precision air conditioner that supplies and circulates temperature-controlled air to a chamber that is an air conditioning target containing an exposure apparatus and the like installed in a clean room.

In the environment around the exposure apparatus for liquid crystal glass substrate, the air conditioning temperature needs to be precisely controlled (accuracy ± 0.01 to ± 0.1 ° C.) because the glass substrate thermally expands due to temperature change.

Such an exposure apparatus is installed in a chamber formed of partition walls or the like in a clean room, and a precision air conditioner different from the air conditioner for the clean room is installed under the floor of the clean room. In the chamber, the temperature controlled air is supplied and circulated precisely.

This precision air conditioner consists of a refrigeration cycle, and the air from the chamber is cooled by the evaporator to a temperature (for example 17 ° C) lower than the set temperature, and it is heated to the set temperature (for example 23 ° C) by the reheat electric heater Supply and circulate to the chamber as conditioned air.

Here, although the heat absorption part which is an evaporator of a refrigeration cycle is installed in a clean room to air-condition the inside of a chamber, the condenser which becomes a heat dissipation part is installed outside a clean room as an outdoor unit with a compressor The unit and the outdoor unit are connected by refrigerant piping to form an air-cooling type air conditioner. Alternatively, when installing a condenser serving as a heat dissipating unit under the floor of a clean room as a water cooling system, a cooling water supply device is installed outside the clean room, and a water cooling air conditioner in which the heat dissipating portion and the cooling water supply device are connected by water cooling piping. For example, various types have been proposed (Patent Document 1).

However, precise temperature control in which conditioned air cooled to a temperature lower than the set temperature by the evaporator is heated to the set temperature by the reheat electric heater has a problem that the running cost of the electric heater increases.

Therefore, as proposed in Patent Document 2, the hot gas of the refrigeration cycle is utilized, and this is supplied to the hot gas bypass that controls the evaporation temperature by flowing it to the evaporator, and the air blowout side of the evaporator is separately reheated It is proposed to install a condenser and feed hot gas to the reheat condenser, heat the air cooled by the evaporator with the reheat condenser, and then precisely control the temperature with the reheat electric heater It is done.

In this patent document 2, the hot gas is supplied to the evaporator to control the evaporation temperature, and the temperature of the conditioned air is controlled by the reheat condenser, so the running cost of the reheat electric heater can be reduced to some extent. It is impossible to control the condensation temperature and evaporation temperature of the refrigeration cycle in a responsive and precise manner by the hot gas bypass, and the installation of the reheat electric heater is indispensable.

On the other hand, in Patent Document 3, a condenser for reheating is installed on the outlet side of the evaporator, and the hot gas is controlled by the three-way proportional control valve operated by air pressure to control the bypass amount of the hot gas, thereby reheating It has been proposed that responsive temperature control can be realized with a condenser for eliminating the need for a reheat electric heater.

In this patent document 3, the air from the chamber is cooled to a temperature 5 ° C. lower than the set temperature by the evaporator and then heated to the set temperature by the reheat condenser, and the reheat electric heater is unnecessary. The running cost can be reduced.

JP 2000-283500 A JP, 2009-216332, A Patent No. 3283245 gazette

However, in Patent Documents 1 to 3, cooling water is used as a condenser for exhaust heat recovery, and a cooling water supply device is separately installed outside the clean room, and cooling water piping and heat radiation from the cooling water supply device and the condenser side. It requires work to connect with the department.

In particular, the size of the recent clean room is increasing, and the height of the clean zone where the process equipment such as the exposure apparatus is installed is about 10 m, and the height of the return chamber below the floor is as high as 5 to 6 m. , yet it has become even tens of thousands m ² that floor area, so that the chamber for covering the plurality of process equipment are installed individually in the clean zone. The radiators for radiating the heat of the respective chambers are individually installed in the return chamber, and the cooling water supply device is installed outside the clean room, so the chilled water piping connecting the chilled water supply device and the respective radiators is In addition to being inevitably long, the connection also requires work at a high place and requires a great deal of labor such as heat retention of cold water piping and measures against water leakage.

Further, in Patent Documents 1 to 3, the load of the refrigeration cycle is set to the capacity corresponding to the maximum air conditioning load, and the refrigerant discharge pressure of the compressor is operated as constant, so the exhaust heat of the refrigerant heat absorbed by the evaporator Controls the circulation amount of the cooling water flowing to the condenser, and attempts to match the heat absorption amount and the exhaust heat amount. However, although the water-cooling type that cools the condenser with cooling water can properly control the amount of heat release in the condenser when the air conditioning load is large, the cooling supplied to the condenser side when the air conditioning load is small The water flow rate becomes extremely low, and may fall below the control range of the cooling water flow rate, making stable operation difficult.

That is, in the temperature control of the chamber to be controlled, the temperature difference between the suction air and the blowout temperature is ± 2 ° C. or less in many cases where the air conditioning load is small. On the other hand, the cooling water temperature to be supplied to the condenser is about 18 ° C., and the cooling water temperature is lower than the condensing temperature of the refrigerant (about 70 ° C.). This makes it difficult to operate the refrigeration cycle stably and to adjust the amount of heat removed from the condenser according to the air conditioning load.

Therefore, an object of the present invention is to solve the above-mentioned problems and to provide a precision air conditioner capable of controlling the exhaust heat quantity corresponding to the air conditioning load of the chamber to be controlled while keeping the load of the refrigeration cycle constant.

In order to achieve the above object, the present invention relates to a precision air conditioner for introducing air in a chamber to be air-conditioned installed in a clean room and circulating it in the chamber at a set temperature,
A refrigeration cycle having a hot gas bypass circuit in which a condenser, an expansion valve, and an evaporator are sequentially connected from the discharge side to the suction side of the compressor, and hot gas on the discharge side of the compressor flows to the evaporator.
A heat recovery unit which accommodates the evaporator of the refrigeration cycle, introduces the air from the chamber, is air-conditioned to a set temperature by the evaporator, and is circulated to the chamber;
A heat dissipating unit provided in the clean room and housing a condenser of the refrigeration cycle and provided with a variable capacity fan for air cooling the condenser with air in the clean room;
Precision air conditioner equipped with

In the present invention, the refrigeration cycle, the heat recovery unit, and the heat radiation unit are accommodated in the same casing.

In the present invention, the hot gas bypass circuit includes a proportional control valve, and the heat recovery unit is provided with a temperature sensor for detecting the temperature of the conditioned air cooled by the evaporator, and the detected value of the temperature sensor The proportional control valve is controlled to precisely control the temperature of conditioned air cooled by the evaporator.

In the present invention, a suction pressure control valve that holds a constant refrigerant suction pressure of the compressor is connected to a refrigerant pipe that connects the refrigerant outlet of the evaporator and the suction side of the compressor, and the expansion valve is a thermal expansion valve In the pipe on the upstream side of the suction pressure adjusting valve, a temperature sensitive cylinder of the temperature type expansion valve is provided, whereby the refrigerant evaporation pressure in the evaporator is kept constant.

In the present invention, a high pressure sensor is provided on the high pressure side refrigerant pipe extending from the condenser to the thermal expansion valve, while the variable capacity fan of the heat radiating portion is driven by an inverter device, and the refrigerant is detected by the high pressure sensor The rotation of the variable capacity fan is controlled by the inverter device so that the condensing pressure of the refrigerant is constant, whereby the refrigerant condensing pressure in the condenser is kept constant.

A liquid receiving tank may be connected to the high pressure side refrigerant pipe between the condenser and the high pressure sensor.

A casing for housing the heat recovery unit and the heat radiation unit may be provided in the return chamber of the clean room.

According to the present invention, in accurately controlling the temperature of the air in the chamber to be air conditioned, the temperature of the conditioned air is precisely controlled by flowing the hot gas to the evaporator for conditioning the air in the chamber, and the heat is recovered by the evaporator It is possible to perform stable precise temperature control by exhausting a considerable amount of heat by air cooling with the condenser of the heat radiation unit installed in the clean room, and it is not necessary to install an outdoor unit or a cold water source outside the clean room Exerts an excellent effect of

FIG. 1 is an overall view showing an embodiment of the present invention. It is detail drawing of the refrigerating cycle of the precision air conditioning machine shown in FIG. It is explanatory drawing which showed the refrigerating cycle in FIG. 2 on the Mollier diagram.

Hereinafter, a preferred embodiment of the present invention will be described in detail based on the attached drawings.

First, with reference to FIG. 1, a clean room 10 and a precision air conditioner 13 for air conditioning a chamber 12 as an air conditioning target which covers process equipment 11 such as an exposure apparatus installed in the clean room 10 will be described.

The clean room 10 is formed above the ceiling 17 of the clean zone 16 in which the process equipment 11 such as the exposure apparatus is installed and the chamber 12 is provided, and the clean zone 16 is supplied with clean air. The air supply chamber 18 has a gas supply chamber 18 and a return chamber 20 which is formed under the floor 19 of the clean zone 16 and sucks the air from the clean zone 16. The return chamber 20 and the air supply chamber 18 are connected by a circulation path 21, the clean room air conditioner 22 is provided in the circulation path 21, and clean air is blown to the clean zone 16 in the ceiling 17 in the air supply chamber 18. , And a plurality of fan filter units 23 each having a HEPA and a fan. The air from the return chamber 20 is introduced into the air conditioner 22 through the circulation path 21 and is air-conditioned to the set temperature by the air conditioner 22, and the air-conditioned air passes from the air supply chamber 18 through the high performance filter in the fan filter unit 23. It is cleaned and blown down to the clean zone 16.

In the clean zone 16, a chamber 12 covering the process equipment 11 is installed on the floor 19, and the inside of the chamber 12 is air-conditioned with a precision air conditioner 13 to precisely control the temperature of the process equipment 11 and the surrounding environment of the process equipment 11. It is supposed to be.

In the present invention, the precision air conditioner 13 is installed in the clean room 10, particularly in the return chamber 20. That is, the precision air conditioner 13 introduces the air in the chamber 12 as return air (RA), precisely air-conditions it, supplies heat to the chamber 12 as supply air SA and circulates the heat recovery provided with the evaporator 26 and the circulation fan 27 It comprises the apparatus part 30 provided with the part 28 and compressor 29 grade | etc., And the thermal radiation part 33 provided with the condenser 31 and the capability variable fan 32 for air cooling. Here, the heat radiating portion 33 is provided at least in the clean room 10, particularly in the return chamber 20. Further, as shown in the figure, the equipment unit 30 including the heat recovery unit 28 and the compressor 29 and the like, and the heat radiation unit 33 are accommodated in one casing 14 to form a precision air conditioner 13. The precision air conditioner 13 is provided in the clean zone 16 and the return chamber 20 in the clean room 10, and in particular, may be provided in the return chamber 20.

Next, FIG. 2 demonstrates the refrigerating cycle 25 which comprises the precision air conditioner 13. As shown in FIG.

The refrigeration cycle 25 includes a condenser 31 of a heat radiating portion 33, a liquid receiving tank 34, a temperature type expansion valve 35 as an expansion valve, an evaporator 26 of a heat recovery portion 28, an accumulator 36 from the discharge side to the suction side of the compressor 29. Are sequentially connected by the refrigerant pipe 37 and further branched from the high pressure side refrigerant pipe 37a extending from the discharge side of the compressor 29 to the condenser 31 and provided with a hot gas bypass circuit 40 for flowing hot gas to the evaporator 26 Configured

The refrigeration cycle 25 will be described in more detail.

A pressure switch 41 for detecting an overload of the compressor 29 is provided on the high pressure side refrigerant pipe 37 a on the discharge side of the compressor 29, and the high pressure side refrigerant pipe 37 a is connected to the inlet side of the condenser 31. A condensing pressure adjusting valve 50 is connected to the high pressure side refrigerant pipe 37 a on the inlet side of the condenser 31. The condenser 31 is formed of a fin and a tube, and the condenser 31 is provided with a variable capability fan 32 to form a heat radiating portion 33. The high pressure side refrigerant pipe 37 a on the outlet side of the condenser 31 is connected to the upper part of the liquid receiving tank 34, and the high pressure side refrigerant pipe 37 b is connected to the bottom of the liquid receiving tank 34. A high pressure sensor 42 is connected to the high pressure side refrigerant pipe 37b from the liquid receiving tank 34 to the thermal expansion valve 35, and a high pressure side refrigerant pipe 37b downstream thereof further includes a sight glass 43 for detecting the amount of water, A filter dryer 44 for removing moisture in the refrigerant and a backless valve 45 as a stop valve are connected.

The low pressure side refrigerant pipe 37 c from the thermal expansion valve 35 is connected to the inlet side of the evaporator 26. The evaporator 26 is formed of fins and tubes, and a circulation fan 27 is provided on the outlet side of the evaporator 26 to form a heat recovery portion 28.

A pressure gauge 46, an external pressure equalization introduction valve 47, a strainer 48, and a suction pressure adjusting valve 49 are sequentially connected to the low pressure side refrigerant pipe 37c from the outlet side of the evaporator 26 to the accumulator 36.

The thermal expansion valve 35 is a diaphragm valve, and although the details are not shown, the diaphragm chamber is connected to the temperature sensitive cylinder 52 via the capillary tube 51, and the other diaphragm chamber is connected to the outer equalizing pipe 53. Be done. The temperature sensing cylinder 52 is provided along the low pressure side refrigerant pipe 37 c on the outlet side of the evaporator 26, and the outer equalizing pipe 53 is connected to the outer pressure equalizing introduction valve 47. The temperature type expansion valve 35 has a pressure acting on one of the diaphragms from the temperature sensing cylinder 52 via the capillary tube 51 (a pressure based on the evaporation temperature of the evaporator 26) and a pressure acting on the other of the diaphragms from the outer equalizing pipe 53. The valve opening degree (decompression degree) is controlled by the differential pressure with (the evaporation pressure of the evaporator 26).

In the example shown in the drawing, the example of the thermal expansion valve of the non-uniform type has been described, but it is also possible to use the thermal expansion valve of the internal type or use of the electric expansion valve.

The refrigerant pressure on the downstream side of the suction pressure adjusting valve 49 is input, and the suction pressure of the compressor 29 is adjusted so that the refrigerant pressure becomes constant.

The hot gas bypass circuit 40 includes a bypass pipe 54 connecting the high pressure side refrigerant pipe 37a from the discharge side of the compressor 29 to the condenser 31 and the inlet of the evaporator 26, and a proportional control valve 55 connected to the bypass pipe. It consists of Further, a strainer 56 is connected to the bypass pipe 54 on the upstream side of the proportional control valve 55.

The heat recovery unit 28 is provided with a temperature sensor 58 that detects the temperature of the air supply SA that is air-conditioned by the evaporator 26 and supplied to the chamber 12 by the circulation fan 27. The proportional control valve 55 of the bypass circuit 40 is controlled.

Further, the variable capacity fan 32 of the heat radiating portion 33 is driven to be variable in the number of rotations by the inverter device 60, and the detected value of the high voltage sensor 42 is input to the inverter device 60 so that the detected value of the high voltage sensor 42 becomes constant. The inverter device 60 controls the air volume of the variable capacity fan 32.

In the refrigeration cycle 25 of FIG. 2, the refrigerant gas (hot gas) compressed by the compressor 29 is pressure-controlled by the condensing pressure control valve 50 and mainly passes through the condenser 31 where the rotation of the variable capacity fan 32 is performed. The heat exchange is performed with the air (about 23 to 25 ° C.) in the return chamber 20 that is blown and condensed, and the pressure is reduced by the thermal expansion valve 35 and flows to the evaporator 26. On the other hand, a part of the hot gas from the compressor 29 is controlled in flow rate from the hot gas bypass circuit 40 by the proportional control valve 55 and flows to the evaporator 26 together with the gas-liquid mixed phase refrigerant decompressed by the thermal expansion valve 35. In the heat recovery unit 28, the return air RA from the chamber 12 is introduced, which is cooled by the evaporator 26 to a set temperature ± 0.01 to ± 0.1 ° C., and the chamber 12 as the precise temperature-controlled air supply SA. Supply to

The refrigerant heat recovered by the evaporator 26 is adjusted to the suction pressure of the compressor 29 by the suction pressure adjusting valve 49 as evaporation refrigerant, sucked into the compressor 29 via the accumulator 36 and compressed again into hot gas It is circulated.

First, in the present invention, the compressor 29 is adjusted to the suction pressure by the suction pressure control valve 49, and compresses the evaporative refrigerant which has been superheated (temperature higher by 5 ° C. than the saturated gas line) to a predetermined pressure to obtain hot gas. I assume. The hot gas is supplied to both the condenser 31 of the heat radiating portion 33 and the evaporator 26 through the hot gas bypass circuit 40. At this time, the high pressure sensor 42 detects the pressure on the outlet side of the condenser 31, and based on this, the inverter device 60 controls the air flow of the variable capacity fan 32, and the condensing pressure control valve 50 flows into the condenser 31. Adjust the pressure. Thereby, the heat exchange amount (exhaust heat amount) in the condenser 31 is adjusted, and the condensation pressure in the condenser 31 is kept constant regardless of the fluctuation of the hot gas bypass amount. Since the condensation in the condenser 31 exchanges heat with the air (approximately 23 ° C. to 25 ° C.) in the return chamber 20, the temperature difference between the condensed refrigerant temperature and the air is small, and the variable capacity fan 32 even if the amount of heat release is small. The amount of heat radiation can be properly controlled by the amount of air flow.

Next, the precise temperature control of the charge air SA in the heat recovery unit 28 controls the opening degree of the proportional control valve 55 by the temperature sensor 58 to control the amount of hot gas flowing into the evaporator 26 from the hot gas bypass circuit 40 It is done by doing.

Although this temperature sensor 58 shows an example of detecting the temperature of the charge air SA at the outlet side of the evaporator 26 of the heat recovery unit 28, the temperature sensor 58 detects the temperature of the return air RA at the inlet side of the evaporator 26. A temperature sensor may be separately provided, and the proportional control valve 55 may be controlled by the temperature sensor at its inlet and outlet.

On the other hand, the thermal expansion valve 35 adjusts the degree of pressure reduction to keep the evaporation pressure of the evaporator 26 constant regardless of the amount of hot gas bypass. That is, the outlet side temperature of the evaporator 26 is converted into the pressure of the refrigerant sealed in the temperature sensing cylinder 52, which is introduced into one of the diaphragm chambers of the thermal expansion valve 35 through the capillary tube 51, The evaporation pressure of the refrigerant evaporated in the heater 26 is introduced to the other of the diaphragm chambers of the thermal expansion valve 35 through the outer equalizing pipe 53, and the pressure reduction degree of the thermal expansion valve 35 is adjusted by the differential pressure between both diaphragm chambers. Ru.

Thus, in the evaporator 26, the evaporation pressure is kept constant, and the amount of refrigerant evaporation in the evaporator 26, that is, the amount of heat exchange between the return air RA and the refrigerant is controlled by the amount of hot gas inflow. Precise temperature control is performed according to.

In the refrigeration cycle 25, the heat recovered by the evaporator 26 of the heat recovery unit 28 is exhausted to the air of the return chamber 20 by the condenser 31 of the heat dissipation unit 33. Since the amount of heat to be processed by the machine 13 is sufficiently small, it can be sufficiently processed by the air conditioning of the air conditioner 13. Therefore, it is not necessary to install an outdoor unit for exhaust heat and a chilled water supply device outside the clean room 10 as in the prior art, and to connect them with refrigerant piping.

Further, when performing precise temperature control, in the hot gas bypass circuit 40, the hot gas flow rate is controlled by the proportional control valve 55 in accordance with the air conditioning load of the return chamber 20 and flows to the evaporator 26. At this time, the condenser 31 controls the condensing pressure to a constant value by the detection value of the high pressure sensor 42, and at the same time, the thermal expansion valve 35 controls the evaporation pressure to a constant level. The refrigeration cycle 25 is stably operated by adjusting the suction pressure of

Further, the proportional control valve 55 controls the amount of hot gas according to the air conditioning load fluctuation of the return chamber 20, and the evaporator 26 recovers the heat of the refrigerant according to the air conditioning load. Thereafter, the hot gas compressed by the compressor 29 is introduced into the condenser 31 of the heat radiating portion 33 and dissipated. As described above, since heat is dissipated after heat recovery, when the air conditioning load fluctuates rapidly, matching between the heat recovery amount and the heat release amount in the refrigeration cycle 25 tends to be poor. Therefore, the refrigeration cycle 25 can operate stably.

Next, the refrigeration cycle 25 will be described on the Mollier diagram of FIG.

Fig. 3 shows the refrigeration cycle on the Mollier chart when R407C is used as the refrigerant, the horizontal axis is the specific enthalpy (kJ / kg), the vertical axis is the absolute pressure (MPa), Lg is the saturated gas line of R407C, Ll indicates a saturated liquid line.

First, the suction refrigerant of the compressor 29 is introduced into the compressor 29 at point A (12 ° C., 0.5 MPa) by the suction pressure adjusting valve 49. This point A is in the superheat state on the gas phase side (+ 5 ° C.) sufficiently higher than the saturated gas line Lg, and the refrigerant gas is compressed to the point B (75 ° C., 2.0 MPa) by the compressor 29 . The hot gas at this point B is supplied to the condenser 31 side and the hot gas bypass circuit 40 side, and the pressure is lowered to a point C (1.7 MPa) at the branch point. The hot gas introduced into the condenser 31 passes through the saturated liquid line Ll while maintaining the condensation pressure at the point C by heat radiation, and is cooled from the gas-liquid mixed phase state to the point D (31 ° C) to be the supercooling liquid. .

The degree of supercooling at this point D can be controlled by the thermal expansion valve 35, and the thermal expansion valve 35 reduces the pressure to point E (11 ° C., 0.8 MPa). In the evaporator 26, the pressure at this point E maintains the evaporation pressure. On the other hand, the hot gas from the point C is introduced into the evaporator 26, so that the pressure is lowered to the point F (0.8 MPa) and becomes the evaporation pressure of the evaporator 26. The hot gas at point F and the refrigerant decompressed to point E by the thermal expansion valve 35 flow into the evaporator 26, and the refrigerant exchanges heat with air from the chamber 12 (return air RA). As a result, the refrigerant enters the state of point G and flows from the outlet of the evaporator 26 to the inlet side of the suction pressure adjusting valve 49, and the pressure is adjusted from point G to point A by the suction pressure adjusting valve 49, It is introduced into the compressor 29.

The heat quantity from point C to point D in the refrigeration cycle on this Mollier chart is the heat release amount of the condenser 31, and the heat quantity from point E to point G is the heat quantity change in the evaporator 26, The heat release amount is the total heat amount of the heat amount of the compressor 29 (the heat amount of the point G to the point F) and the evaporation heat amount.

Here, when the amount of hot gas bypass is 0%, the amount of heat of evaporation of the evaporator 26 becomes the amount of heat from point E to point G, and when there is no air conditioning load and the amount of hot gas bypass is 100%, the amount of heat of the compressor 29 The heat is dissipated by the condenser 26, and the specific enthalpy of the refrigerant at the inlet of the evaporator 26 becomes a point H obtained by subtracting the amount of heat of the compressor 29 from the point G. Therefore, the specific enthalpy of the refrigerant at the inlet of the evaporator 26 is 0 H to 100 H, and the specific enthalpy of the refrigerant at the inlet of the evaporator 26 is H H at any of E to H The amount of heat of evaporation according to the air conditioning load, that is, the amount of heat exchanged with air (return air RA) by the evaporator 26 is obtained.

Therefore, by controlling the hot gas bypass amount in the range of 0% to 100% in accordance with the air conditioning load state of the chamber 12, the heat exchange amount according to the air conditioning load can be obtained between point E and point H shown in the figure. It can be adjusted.

The amount of hot gas bypass flowed to the hot gas bypass circuit 40 is such that the amount of heat generated by the compressor can be dissipated when the circulating amount of the refrigerant of the refrigeration cycle 25 is 100%, up to about 70%. Even if it flows, the refrigeration cycle 25 can operate stably. Therefore, by appropriately performing the flow control in the proportional control valve 55, precise temperature control can be performed to ± 0.01 ° C. to ± 0.1 ° C. with respect to the set temperature (eg, 23 ° C.).

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made. That is, although the thermal expansion valve has been described as an example of the expansion valve, even if it is performed by the electric expansion valve or in FIG. 3, the refrigerant condensation pressure, evaporation pressure and compressor suction pressure when R407 is used as the refrigerant. Although an example has been shown, it goes without saying that the compression capacity, condensing pressure and evaporation pressure of the compressor may be changed according to the air conditioning load and the processing air volume.

Reference Signs List 10 clean room 12 chamber 14 casing 25 refrigeration cycle 26 evaporator 28 heat recovery unit 29 compressor 31 condenser 32 variable capacity fan 33 heat radiating unit 40 hot gas bypass circuit

Claims

In a precision air conditioner for introducing air in a chamber to be air-conditioned installed in a clean room, circulating this in the chamber at a set temperature,
A refrigeration cycle having a hot gas bypass circuit in which a condenser, an expansion valve, and an evaporator are sequentially connected from the discharge side to the suction side of the compressor, and hot gas on the discharge side of the compressor flows to the evaporator.
A heat recovery unit which accommodates the evaporator of the refrigeration cycle, introduces the air from the chamber, air-conditions to a set temperature by the evaporator, and circulates to the chamber
A heat dissipating unit provided in the clean room and housing a condenser of the refrigeration cycle and provided with a variable capacity fan for air cooling the condenser with air in the clean room;
A precision air conditioner characterized by having
The precision air conditioner according to claim 1, wherein the refrigeration cycle, the heat recovery unit, and the heat radiation unit are accommodated in the same casing.
The hot gas bypass circuit includes a proportional control valve, the heat recovery unit is provided with a temperature sensor for detecting the temperature of the conditioned air cooled by the evaporator, and the detected value of the temperature sensor indicates the proportional The precision air conditioner according to claim 1 or 2, wherein the control valve is controlled, whereby the conditioned air cooled by the evaporator is precisely temperature controlled.
A suction pressure control valve that holds the suction pressure of the refrigerant in the compressor constant is connected to a refrigerant pipe that connects the refrigerant outlet of the evaporator and the suction side of the compressor, and the expansion valve is a thermal expansion valve. The precision air conditioner according to claim 3, wherein a pipe on the upstream side of the suction pressure control valve is provided with a temperature sensitive cylinder of the temperature type expansion valve, whereby the refrigerant evaporation pressure in the evaporator is kept constant.
The high pressure side refrigerant piping from the condenser to the thermal expansion valve is provided with a high pressure sensor, while the capacity variable fan of the heat radiating portion is driven by an inverter device, and the condensing pressure of the refrigerant detected by the high pressure sensor is The precision air conditioner according to claim 4, wherein the rotation of the variable capacity fan is controlled by an inverter device so as to be constant, whereby the refrigerant condensing pressure in the condenser is kept constant.
The precision air conditioner according to claim 5, wherein a liquid receiving tank is connected to a high pressure side refrigerant pipe between the condenser and the high pressure sensor.
The precision air conditioner according to claim 2, wherein a casing for accommodating the heat recovery unit and the heat radiation unit is provided in a return chamber of the clean room.