JP2008057938A - Air conditioner for conditioning outside air - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To simplify circuit configuration and to dispense with a control valve for switching a passage by setting the operation of a post-stage air conditioner to conditions of a fixed refrigerating cycle state throughout the year. <P>SOLUTION: An outside air conditioner for taking in and conditioning outside air into target air is provided with a precooling cold water coil 64 in an air duct which connects an outside air inlet to a target air blowoff port; a pre-stage air conditioner comprising a preheating hot water coil 65 and a humidifier 66; and the post-stage air conditioner comprising a direct-expansion type coil, a reheating coil and a blower fan. The pre-stage air conditioner is constituted to take in outside air from the outside air inlet and to control operation so that properties of post-stage inlet air to be blown to the post-stage air conditioner are within a predetermined range, and the post-stage air conditioner is constituted to condition the predetermined target air by the operation of specified control. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an air conditioner such as a clean room, and more particularly to an outside air conditioning air conditioner that takes in outside air and supplies target air adjusted to a predetermined constant temperature and constant humidity.

  In indoor air conditioning in clean rooms, computer rooms, semiconductor factories, etc., the temperature at which constant dry bulb temperature and constant humidity (hereinafter referred to as indoor target air) is adjusted throughout the year to maintain the indoor air condition. Air conditioning needs to be supplied. At that time, the temperature adjustment processing is often divided into an indoor circulation air conditioner and an outside air conditioning air conditioner. In this case, the temperature and humidity of the outside air taken in by the outside air conditioning air conditioner change greatly throughout the year. For example, the outside air is hot and humid in summer, and the outside air is dry at low temperature in winter. For this reason, a dehumidification reheat control system has been conventionally employed as an outside air conditioning air conditioner in order to ensure the degree of freedom of the temperature adjustment range and to further improve the stability of humidity.

  Furthermore, the constant temperature and humidity (temperature and humidity) indicating the air condition required by the indoor target air is relatively low temperature and dry air (for example, the temperature is 23 degrees Celsius and the relative humidity is 45%. In this case, the dew point temperature is 10 degrees Celsius). Therefore, it is necessary for the outside air conditioning air conditioner to cool and dehumidify the outside air in the summer to the dew point temperature (10 degrees Celsius). For this reason, the temperature of the cooling water (or refrigerant) necessary for the cooling coils in the economical number of coil rows. Must be between 6 degrees Celsius and 7 degrees Celsius. That is, a refrigeration apparatus for cooling the cooling water to 6 degrees Celsius to 7 degrees Celsius is required.

  By the way, as the air state of the indoor circulating air, the return air temperature rises due to heat generated by indoor production equipment and fan lighting that circulates the air, but in a clean room, for example, it circulates with a large air volume for air dust filtration. Even in places with high heat generation, heat generation can be processed by blowing out air in the state of 5 to 6 ° C difference, that is, about 23 ° C-6 ° C = 17 ° C, and indoor target air is 23 ° C and 45% RH Can be maintained. Therefore, in order to cool the blown air to 17 ° C., even if considering the economical number of coils, for example, it is possible to cool with cold water having a cold water temperature of 10 ° C. with a sufficient air / water heat exchanger provided in the circulating air conditioner. .

In the case of a compression refrigerator, the refrigerant state change in the refrigeration cycle is shown by a Mollier diagram (pressure P-specific enthalpy diagram), and the temperature of cold water to be frozen can be raised from 7 ° C. to 10 ° C. in the evaporator. This means that the evaporation pressure of the refrigerant is increased, and in the coefficient of performance COP of the refrigerator (the ratio between the cooling capacity and the energy consumption (compressor power)), the COP increases due to the reduction in the work of the compressor. Become. This is because the condensing pressure is the same and the evaporation pressure is high, reducing the required compression work of the compressor. For example, a refrigerator having a COP of 5.5 at 7 ° C. has a capacity up to 8 at 10 ° C. In other words, it can be frozen with energy saving.

Here, for example, in a clean room for semiconductor manufacturing, the external air load is about 30%, and the load on the other circulating air side and the load on the production apparatus (this is also often sufficient for cooling with chilled water of 10 ° C. or higher) is 7 It is relatively expensive. Also, if the outside air load is divided into summer peak load 27 ° C WB → 15 ° C, 15 ° C → 10 ° C and two-stage cooling is performed, the specific enthalpy is (85-43) kg / kg (DA) ( 43-30) kg / kg (DA), which requires 7 ° C. cold water, that is, the ratio required for cooling dehumidification from 15 ° C. to 10 ° C. WB is 13/45 = 0.24, As for the ratio of 0.24, the outdoor air load is a ratio of 0.3 of the total building load, and the necessary ratio of 7 ° C. cold water cooling is the ratio of 0.24 × 0.3 = 0.08 of the total building load. Become.

In order to cool and dehumidify the outside air and cool the circulating air in the room with a single refrigerator, it is not necessary to freeze the entire cooling water return water so that it becomes a cooling water of low temperature (6 degrees Celsius to 7 degrees Celsius). It consumes energy as necessary. Therefore, two refrigerators are used, one is used for a refrigerator that performs low-temperature freezing to obtain the above-described low-temperature cooling water (6 degrees Celsius to 7 degrees Celsius), and the other one is the above-described low-temperature cooling. If it is used as a high-temperature cold water refrigerator for obtaining cooling water having a temperature higher than that of water, an air conditioning system with a small heat energy loss can be constructed. For example, based on the previous calculation, if an air conditioning system that adds this turbo chiller that covers only 8% low-temperature chilled water load to a 10 ° C. chilled water refrigeration turbo chiller that covers 92%, it is 5.5 in terms of COP. × 8/100 + 8 × 92/100 = 7.8, which greatly saves energy in the entire building. Even if the COP is reduced by downsizing or changing the type of the low-temperature cold water refrigerator, it is clear that the COP is improved in the entire building.

In addition, the present applicant has invented an outside air conditioning air conditioner with less energy loss than a conventional device, and has already filed a patent application (Patent Document 1).
Patent application, Japanese Patent Application No. 2005-017028 This application is an improvement of the above-mentioned patent application invention. Below, the content of the said patent application invention is demonstrated to a necessary extent. FIG. 4 shows an overall view of the system of this patent application invention, FIG. 5 shows an outside air conditioning air conditioner of this system, and FIG. 6 shows a state transition diagram in the humid air diagram of this system.

  In FIG. 4, a clean room 51 is provided inside the air conditioning room 50, and a semiconductor manufacturing apparatus or the like is installed in the clean room 51. Air is circulated in order to maintain the cleanliness of the internal clean room 51 of the air-conditioning room 50 and the room temperature and humidity in a predetermined state. That is, a fan filter unit 52 is provided on the ceiling of the clean chamber 51, and an opening 53 formed of a punching hole is provided at an appropriate location of the clean chamber 51, for example, the floor surface. The entire floor surface of the clean chamber 51 may be the open hole 53. All of the air in the clean chamber 51 exits from the open hole 53, and most of the air is configured to circulate via the coil unit 54 and the fan filter unit 52. The remaining portion of the air exiting from the opening hole 53 is discharged to the outside by the fan 55 with a damper. In addition, the air adjusted from the outside air conditioning air conditioner 60 is supplied to the upstream side of the coil unit 54, mixed with the return air that circulates mostly from the opening hole 53, cooled in the coil unit 54, and then into the clean chamber 51. Supplied. The coil unit 54 is configured such that a part of the cold water from the refrigerator 57 circulates through the branch pipe A.

  The outside air conditioning air conditioner 60 has a cold air coil 64 for precooling, a hot water coil 65 for preheating, a humidifier 66, and a direct expansion in a case 61 provided with an outside air inlet 62 and a regulated air blowing port 63 as a supply duct connection port at the outlet end. The type coil 67, the reheating coil 68, and the blower fan 69 are sequentially arranged downstream. Note that the blower fan does not need to be in this particular place, and may be located between any of the pre-cooling cold water coil 64 and the reheating coil 68. The cold water from the refrigerator 57 flows into the inlet of the precooling cold water coil 64 through the pipe 57 a, and is returned to the refrigerator 57 through the pump 58 from the outlet of the cold water coil 64. The steam generated by the boiler 70 is discharged to the return water pipe as drain after heat exchange via the heat exchanger 72, and the warm water heated by the heat exchanger 72 is circulated via the pump 73 and the preheating hot water coil 65. To do.

  FIG. 5 shows the details of the conventional system of the directly expanded coil 67 and the reheating coil 68. As shown in FIG. 5, the direct expansion coil 67 constitutes a first closed circuit including a compressor 81, a first condenser 82, and a first expansion valve 83. The first closed circuit constitutes a refrigeration cycle, and when the liquefied refrigerant suddenly expands from the first expansion valve 83 and the gasified refrigerant flows through the direct expansion coil 67, it takes away the latent heat of evaporation and cools it. As a small-capacity low-temperature refrigeration, it is easy to produce low temperatures. However, there is a drawback that the energy consumption efficiency is not as good as that of a turbo refrigerator. However, for example, even if less than 10% of the outside air cooling load is operated with COP3, the other 90% is operated with COP8 (total COP = 0.1 × 3 + 0.9 × 8 = 7.5). It is clear that it is more energy efficient than COP5.5, which freezes the water. Further, in order to control the first closed circuit and to have a function to be described later, an adjustment valve 86 is inserted between the direct expansion coil 67 and the compressor 81, and the compressor 81, the first condenser 82, A control valve 87 is inserted between the first condenser 82 and the expansion valve 83, and a control valve 88 is inserted between the first condenser 82 and the expansion valve 83.

  A bypass path is provided between the upstream side of the control valve 87 and the upstream side of the control valve 88 in the first closed circuit, and the control valve 89 and the reheating coil 68 are provided in the bypass path. By flowing a part of the high-temperature gas compressed by the compressor 81 through the bypass passage to the reheating coil 68, the outside air passing therethrough can be heated. The reheating coil 68 has a second closed circuit that passes through a partial pipeline upstream of the control valve 88 and passes through the expansion valve 90, the evaporator 91, the control valve 86, the compressor 81, and the control valve 89. It is composed. A control valve 92 is inserted upstream of the expansion valve 90 of the second closed circuit. Furthermore, an energy recovery conduit 93 that communicates the first condenser 82 and the evaporator 91 is provided. The second closed circuit constitutes a heat pump together with the first closed circuit, and is a circuit for flowing high-temperature gas through the reheating coil 68 and recovering excess compression energy from the compressor 81 as cold energy.

  The control valves 87, 88, 89, and 92 are opened / closed and flow rate controlled by a controller (not shown). In order to open and close the control valves 87, 88, 89, 92, for example, in the wet season with high humidity such as summer, the control valves 87, 88, 89 are opened and the control valve 92 is closed. In this case, the refrigerant flows in the direction indicated by the arrows in the double arrows (solid line and dotted line) in the figure. A solid line indicates a flow path that flows through the directly expanded coil 67, and a dotted line indicates a flow path that flows through the reheating coil 68. In the dry season with low humidity such as winter, the control valves 89 and 92 are opened, and the control valves 87 and 88 are closed. In this case, the refrigerant flows in the direction of the arrow through the flow path indicated by the (single) solid arrow.

  FIG. 6 shows the case where the air condition (R) of the clean room is a temperature of 23 degrees Celsius (dry bulb temperature) and a relative humidity of 45%, and the summer outdoor air (S) is a temperature of 33 degrees Celsius and a relative humidity of 63%. FIG. 4 is an air diagram (wet air diagram) showing a change in the state of the outside air by the air conditioner when the outside air (W) in winter has a dry bulb temperature of 0 degrees Celsius and a wet bulb temperature of Celsius (−3) degrees. As a state of air condition R (corresponding to indoor target air), the dew point temperature is 10 degrees Celsius.

  First, in the summer state, the state S of the taken-in outside air is cooled to the air state point A close to the saturation line by the pre-cooling chilled water coil 64, and further the air state point E (15 degrees Celsius, 100% while gradually approaching the saturation curve). ) Until cooled. The air state point E is, for example, a point of maximum capacity that can be cooled by a cold water coil for pre-cooling of a row number coil that is economical at a cold water flow temperature of 10 ° C. The air at the air state point E is further cooled to the air state point D by the direct expansion type cooling coil 11. The outside air at the point D may be heated to the point R by the reheating coil 68, but the air circulating inside the air conditioning chamber 50 is cooled by the coil 54, so that the temperature difference can be made uniform by mixing the air. It is sufficient to heat to the temperature of point Q (which corresponds to the target air) to mix to help cool the circulating air. That is, the direct expansion coil 67 and the reheating coil 68 are simultaneously operated. Next, in the winter, in order to adjust the outside air (W) to satisfy the air condition (R), the outside air (W) introduced first is heated to the air state point E by the preheating hot water coil 65. The latter humidifier is water humidified and performs adiabatic humidification, so that the humidifier is heated to a temperature value substantially equal to the wet bulb temperature at the air state point D. Then, the air at the air state point E is water-humidified by the humidifier 66 so that it becomes the air state point at the point D. Thereafter, it is heated to the temperature of the point Q as in the summer. In winter, since only the reheating coil 68 is operated, it is difficult to adjust the flow rates of the first closed circuit and the second closed circuit.

  As described above, the invention described in Patent Document 1 is provided with a control valve to control the switching of the pipeline according to the state of the outside air. Therefore, complicated piping and a large number of control valves are required, which increases the initial cost. In addition, since a large number of valves are switched and operated depending on the state of the outside air, it takes time until the system is stabilized, and the adjusted target air state becomes unstable. Accordingly, the present invention employs the following means in order to solve these problems.

In order to solve the above problems, the present invention employs the following means. That is,
According to the first aspect of the present invention, in the outside air conditioner that takes in outside air and adjusts it to target air, a precooling cold water coil, a preheating hot water coil, and a humidifier are connected to an air passage connecting the outside air inlet and the target air blowing port. A front-stage air conditioner and a rear-stage air conditioner composed of a direct expansion coil, a reheating coil, and a blower fan, and the front-stage air conditioner takes in outside air from the outside air intake and sends it to the rear-stage air conditioner. The operation is controlled so that the state of air falls within a predetermined range, and the latter-stage air conditioner controls a predetermined target by controlling the state of the refrigerant inlet and outlet at each part in the refrigeration cycle to be substantially constant. It is characterized by being configured to adjust the air.

  According to a second aspect of the present invention, in the first aspect of the invention, the predetermined range is humid air in which the specific enthalpy of the rear-stage inlet air is the same as the specific enthalpy of the target air and the relative humidity is in the predetermined range. It is characterized by being.

  According to a third aspect of the present invention, in the first aspect of the present invention, the specific enthalpy of the rear stage inlet air is the same as the specific enthalpy of the target air, The humidity is in the range of 80% to 100%.

  The invention according to claim 4 is the invention according to any one of claims 1 to 3, wherein the predetermined range is such that the relative humidity is higher when the specific enthalpy of the outside air is higher than the specific enthalpy of the target air. When the specific enthalpy of the outside air is lower than the specific enthalpy of the target air, the relative humidity is closer to the saturation line than about 90%.

  According to the present invention, since the operation of the rear-stage air conditioner can be made into a condition of a constant refrigeration cycle state for a year, the circuit configuration is simplified, and a control valve for switching the flow path is unnecessary at the same time. It becomes. In addition, there is no fluctuation in heat exchange between the direct expansion coil and the reheating coil of the refrigerant, and a constant heat exchange state can always be realized throughout the year. Accordingly, not only the initial cost of piping and the like is reduced, but also an effect that stable operation is facilitated can be obtained. Moreover, from this, the effect that the temperature and humidity of the target air can be easily made constant can be obtained.

  FIG. 1 shows the overall configuration of an embodiment of the present invention, and FIG. 2 shows a state transition diagram in the wet air diagram of this embodiment. As shown in FIG. 1, the pre-stage air conditioner 10 includes a pre-cooling cooling coil 64, a pre-heating hot water coil 65, and a humidifier 66, and the post-stage air conditioner 20 includes a direct expansion coil 67, a re-heating coil 68, and a blower fan. 69. Note that the blower may be located anywhere in the rear stage, and further in the front stage. The outside air adjusted by the front air conditioner (hereinafter referred to as rear inlet air) is blown to the rear air conditioner inlet.

  The cooling coil 64 for pre-cooling cools the outside air when the specific enthalpy of the taken-in outside air is larger than the specific enthalpy of the target air (during the wet season). This cooling temperature is detected by the thermometer 11, and the flow rate of cooling water from the refrigerator 57 (see FIG. 4) is controlled by the controller 12 by the control valve 64a. For example, when the state of the outside air is “S” shown in FIG. 2, cooling is performed from the point S to the air state point E via the air state point A. In the wet season, the preheating hot water coil 65 and the humidifier 66 are in a resting state. Note that when the humidifier is provided with a function of removing water-soluble gas in the air, the humidifier 66 may be operated, but the point E is substantially saturated and the air state point remains E.

  The preheating hot water coil 65 and the humidifier 66 heat and humidify the outside air when the specific enthalpy of the outside air is smaller than the specific enthalpy of the target air (during the dry season). In the heating by the preheating hot water coil 65, the dew point temperature of the rear stage inlet air is detected by the wet bulb thermometer 15, and the controller 16 controls the flow rate of hot water from the heat exchanger 72 (see FIG. 4) by the control valve 65a. For example, when the state of the outside air is “W” shown in FIG. 2, heating is performed from point W to point F, that is, to a temperature value substantially the same as the wet bulb temperature at the air state point G. The humidifier 66 is a water humidifier (washer) and adiabatically humidifies, so that the state of the air in the humidifier 66 changes along the isohumidity bulb temperature line (substantially equal to the isoenthalpy line). The humidifier 66 is designed (configured) so that the relative humidity is preferably about 90% or more. As a result, for example, the air in the state F of FIG. In the dry season, the cooling cold water coil 64 is put into a resting state. As a result, in both the wet season and the dry season, the specific enthalpy of the rear-stage inlet air is at the air state point E or the air state point G on the “Ie” line.

  Next, the direct expansion coil 67, the reheating coil 68, and the blower fan 69 always perform constant steady operation in both the wet season and the dry season. That is, in the direct expansion coil 67, the refrigerant flows through a cycle including the compressor 81, the control valve 87, the condenser 82, the control valve 88, and the expansion valve 83, and the rear inlet air is changed from the specific enthalpy “Ie” to the specific enthalpy. Cool to “Id”. As a result, the post-stage inlet air at the point “E” on the specific enthalpy “Ie” line and the post-stage inlet air at the point “G” are saturated to the point “D” on the saturation curve. In addition, the reheating coil 68 is branched by a part of the refrigerant that has been compressed by the compressor 81 and becomes high temperature, and flows through the control valve 89, the reheating coil 68, the control valve 88, and the expansion valve 83. The rear stage inlet air coming out of the expansion coil 67 is heated. By this heating, the humid air at the point “D” on the saturation curve is heated to the point Q to become the desired target air. Note that the blower fan 69 rotates at a constant speed, and flows a target air with a constant air volume.

  FIG. 3 shows a transition diagram in the case of cooling by the direct expansion coil 67 at different relative humidity points on the specific enthalpy “Ie” line. In the case of the relative humidity “H0”, the absolute humidity is equal to the absolute humidity at the point D and ideally reaches the point D. However, actually, a phenomenon such as supercooling occurs, and the point D cannot be reached. In the case of relative humidity “H1”, this is the limit at which point D can be reached. In the case of relative humidity “H2” and relative humidity “H3”, the point D is reached after reaching the saturation curve. For the purpose of the present application, the relative humidity may be H2 or H3. However, if the relative humidity is too low, the humidifier 66 cannot remove the water-soluble gas such as ammonia as the water-soluble gas in the air. Conversely, if a high relative humidity is required, it becomes difficult to design and manufacture the humidifier. Accordingly, the relative humidity is desirably about 90% at the outlet of the humidifier 66 during winter peak humidification, and this embodiment has been described with respect to the case where this is adopted.

  In the embodiment described above, the latter-stage air conditioner can be operated under constant conditions throughout the year. This eliminates the need for circuit switching, which not only lowers the cost of the equipment, but also simplifies the control and stably satisfies the target air conditions. Further, since the relative humidity of the rear-stage inlet air in the dry season is designed to be 90%, water-soluble gas such as ammonia can be easily removed and the humidifier can be easily designed.

  The technical scope of the present invention is not limited to the embodiment (or example) described above. For example, the dew point E (see FIG. 2) may not be on the specific enthalpy line of the target air (R). Further, even if the relative humidity of the rear stage inlet air is other than 90%, it belongs to the technical scope of the present invention.

The structure of the principal part of embodiment which implemented this invention is shown. The state transition diagram in the humid air line figure of this embodiment is shown. It is a figure explaining the selection criteria of relative humidity in the humidifier of this embodiment. An overall view of a conventional apparatus is shown. Explanatory drawing of the principal part of a conventional apparatus is shown. The state transition diagram of a conventional apparatus is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Pre-stage air conditioner 11 Thermometer 12 Temperature controller 15 Wet bulb thermometer 16 Temperature controller 20 Post-stage air conditioner 64 Preliminary cold water coil 65 Preheat hot water coil 66 Humidifier 67 Direct expansion type cooling coil 68 Reheat coil 69 Blower fan

Claims (4)

In the outside air conditioner that adjusts to the target air by taking in outside air, the front air conditioner and the direct expansion type consisting of a precooling cold water coil, a preheating hot water coil and a humidifier in the air passage connecting the outside air inlet and the target air blower opening A rear-stage air conditioner comprising a coil, a reheating coil, and a blower fan, and the front-stage air conditioner takes in outside air from the outside air intake and sends the air to the rear-stage air conditioner in a predetermined range. The operation is controlled so as to enter the inside, and the latter-stage air conditioner is configured to adjust the predetermined target air by controlling the state of the inlet and outlet of the refrigeration to be substantially constant in each part in the refrigeration cycle. An outside air conditioning air conditioner characterized by that. 2. The outside air conditioning air conditioner according to claim 1, wherein the predetermined range is humid air in which the specific enthalpy of the rear-stage inlet air is the same as the specific enthalpy of the target air and the relative humidity is in the predetermined range. . 3. The predetermined range is characterized in that the specific enthalpy of the rear inlet air is the same as the specific enthalpy of the target air, and the relative humidity is in the range of 80% to 100%. The outside air conditioning air conditioner according to 1. The predetermined range is that the relative humidity is 100% when the specific enthalpy of the outside air is higher than the specific enthalpy of the target air, and the relative humidity is about 90% when the specific enthalpy of the outside air is lower than the specific enthalpy of the target air. The outside air conditioning air conditioner according to any one of claims 1 to 3, wherein the air conditioner is closer to a saturation line.

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