JPH0554020B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to an air conditioner, and more specifically, a natural circulation type refrigeration system comprising a first evaporator installed in an area to be cooled and a first condenser installed higher than the first evaporator. and a compression refrigeration cycle comprising a second evaporator installed in parallel with the first evaporator, a second evaporator installed in parallel with the first condenser, a pressure reducing means, and a compressor. . (Prior art) As described in Japanese Utility Model Publication No. 57-54527 (Japanese Utility Model Publication No. 55-67966), this type of air conditioner is used in areas where there is a cooling load throughout the year, such as computer rooms. It has been traditionally used for air conditioning to save power consumption. This will be briefly explained based on Fig. 7.
A natural circulation refrigeration cycle N is formed by connecting a first evaporator 60 installed in the indoor unit A and a first condenser 61 installed in the outdoor unit B installed higher than the indoor unit A; 1 evaporator 60
A compression refrigeration cycle C consisting of a second evaporator 62 provided in parallel with the first condenser 61, a second condenser 63 provided in parallel with the first condenser 61, a compressor 64, and a pressure reducing means 65 is provided. Due to the size of the refrigeration system, only the natural circulation refrigeration cycle was operated independently during low loads, and both refrigeration cycles were operated together during high loads. Note that 66 and 67 are fans, respectively, and 68 is an on-off valve. (Problems to be Solved by the Present Invention) However, in the above-mentioned conventional refrigeration cycle, neither the natural circulation type refrigeration cycle nor the compression refrigeration cycle has a capacity reduction means, and the natural circulation type Only one of two operation patterns could be selected: independent operation of the refrigeration cycle or combined operation of the natural circulation refrigeration cycle and the compression refrigeration cycle. For this reason, when the air conditioner is started, there is a problem that the air conditioner cannot be operated in accordance with the cooling load, and when the air conditioner is in normal operation, there is a gap between the full capacity of the air conditioner and the cooling load. A large imbalance tends to occur, and as a result, there is a problem in that the temperature of the area to be cooled, especially the temperature of the air blown out from the indoor unit A, cannot be precisely controlled. (Means for Solving the Problems) Therefore, the present invention provides a first
A natural circulation refrigeration cycle N consisting of evaporators 2 and 3 and a first condenser 5 installed at a higher location than the evaporators 2 and 3.
and second evaporators 11, 11 installed in parallel with the first evaporators 2, 3, second condensers 12, 12 installed in parallel with the first condenser 5, pressure reducing means 13, 13, and a compressor 9, 9, the natural circulation type refrigeration cycle N and the compression refrigeration cycle C are each provided with capacity reducing means, and the first and second evaporators 2,
3, 11, and 11, and a setting means 22 for setting this air temperature, and the setting set by the setting means 22 from the detected temperature t detected by the detection means 18. temperature
A control means 21 is provided for controlling the operation of the air conditioner based on the temperature difference Δt obtained by subtracting _t0 , and the control means 21 controls the temperature difference Δt to be a predetermined value including zero when starting the air conditioner. Depending on whether it is within the range, exceeds the predetermined range, or is below the predetermined range, the natural circulation refrigeration cycle N is at full capacity and the compression refrigeration cycle C is at the first partial capacity, or the natural circulation refrigeration cycle N is at full capacity. capacity and the compression refrigeration cycle C has a higher capacity than the first partial capacity.
The air conditioner is operated at partial capacity, or the natural circulation refrigeration cycle N is at full capacity and the compression refrigeration cycle C is at zero capacity, and furthermore, during normal operation of the air conditioner, the temperature difference Δt is adjusted at regular intervals. Based on this, the capacity of the air conditioner is increased, maintained, or reduced by one level, and at the time of this reduction, the reduction in the capacity of the compression refrigeration cycle C is given priority over the reduction in the capacity of the natural circulation refrigeration cycle N. (Function) Since the present invention has been achieved as described above, when starting the air conditioner, even when the temperature difference Δt is large, the air conditioner is operated not at full capacity but at partial capacity, for example in the area to be cooled. This prevents dew build-up on the installed computer, and even when the temperature difference △t is negative, only the natural circulation refrigeration cycle N is operated to reduce the slow start-up of the natural circulation refrigeration cycle N. In addition, during normal operation of the air conditioner, by adjusting the capacity of the natural circulation refrigeration cycle N and the compression refrigeration cycle C according to the load, the full capacity of the air conditioner can be used to meet the cooling load. It can be finely adjusted depending on the situation, and therefore stable control of the indoor temperature in the area to be cooled is possible.Moreover, when the capacity of the air conditioner is reduced, the capacity reduction of the compression refrigeration cycle C is prioritized over the capacity reduction of the natural circulation refrigeration cycle N. As a result, power consumption can also be kept low. (Example) Hereinafter, an example of the present invention will be described based on the drawings. The ones shown in Figures 1 and 5 are a natural circulation refrigeration cycle N and a compression refrigeration cycle C consisting of two systems.
The cooling target area E is an air conditioner equipped with a computer room that is cooled throughout the year. The natural circulation refrigeration cycle N includes two first evaporators (hereinafter referred to as 1A) disposed in the indoor unit 1.
(1B evaporator) 2, 3, and an outdoor unit 4 located at a higher location than the indoor unit 1.
The first condenser 5 is disposed in the first condenser 5. Specifically, the 1A and 1B evaporators 2 and 3 are connected in parallel, this parallel circuit and the first condenser 5 are connected in series to form a refrigerant circuit, and each of the evaporators 2 and 3 is connected in series. Electromagnetic on-off valves (hereinafter referred to as A on-off valve and B on-off valve) 6 and 7 are interposed on the refrigerant inflow side of the refrigerant, respectively. Note that 8 is a liquid receiver. Thus, by opening the A and B on-off valves 6 and 7, the refrigerant sealed in the circuit absorbs heat and evaporates in each of the evaporators 2 and 3, and this refrigerant vapor flows upward due to its specific gravity. move the first condenser 5
It radiates heat and condenses, and then returns to the evaporators 2 and 3 through the liquid receiver 8 under its own weight and is circulated. Further, by closing one of the on-off valves 6 and 7, for example, the A on-off valve 6, the 1A
By stopping the operation of the evaporator 6, the capacity of the natural circulation type refrigeration cycle N can be approximately halved. That is, the opening/closing valves 6 and 7 constitute a capacity reducing means for reducing the capacity of the refrigeration cycle N. On the other hand, the compression refrigeration cycle C consists of a pair of identical compression refrigeration cycles C1 and C2, and each compression refrigeration cycle C1 and C2 has a compressor 9 and a recycler, respectively, each having a capacity control mechanism (not shown). It is equipped with a heating device 10. (Hereinafter, only C1 will be explained.) For details, see 1A and 1B above.
Consisting of a second evaporator 11 arranged in parallel on the leeward side of the evaporators 2 and 3, a second condenser 12 arranged in parallel on the leeward side of the first condenser 5, the compressor 9, and an expansion valve. A main circuit is formed by sequentially connecting the pressure reducing means 13 and an electromagnetic on-off valve 15, the reheater 10, and a capillary reach tube between the discharge side of the compressor 9 and the outlet side of the pressure reducing means 13. A reheat circuit is provided in which 14 are sequentially inserted. Further, the compressor 9 is a two-cylinder reciprocating compressor, and by unloading one of the two cylinders by the capacity control mechanism, 100% operation and 50% operation can be performed. There is. The capacity control mechanism selectively applies the discharge pressure and suction pressure of the compressor 9 via the three-way valve 20, thereby switching between loading and unloading. Further, the reheater 10 operates by opening the on-off valve 15, so that the capacity of the compression refrigeration cycle C1 can be reduced. In addition, in FIG. 1, 16 is an accumulator and 17 is a liquid receiver. Therefore, the compression refrigeration cycle C consisting of the refrigeration cycles C1 and C2 is different from each refrigeration cycle C.
1. By combining the starting and stopping of the compressor 9 in C2, the operation and stopping of the capacity control mechanism and the reheater 10, the capacity can be reduced in six stages as shown in Table 1, and the capacity can be controlled in a total of seven stages. We are making it possible to do so.

[Table] In the table, in the compressor section, ◎ indicates 100% operation, ○ indicates 50% operation, and ● indicates stop. Also, in the reheater section, the ☆ mark indicates the operating time.
The mark ★ indicates the time of stop. As described above, in the compression refrigeration cycle C, the capacity reduction means is constituted by the switch for controlling the drive of the motor of the compressor 9, the capacity control mechanism and the three-way valve 20, and the reheat circuit, which will be described later. -ing In addition, in Figures 1 and 5, 19 is an indoor fan, 2
5 is an outdoor fan; 18 is a detection means consisting of a thermistor for detecting the temperature of the air blown from the indoor fan 19; and 26 is a duct that sends the air blown from the indoor fan 19 to the area to be cooled. As mentioned above, the air conditioner is composed of a natural circulation refrigeration cycle and a compression refrigeration cycle, each of which has a capacity reduction means, and by controlling the capacity reduction means in combination, as shown in Table 2. It is designed so that it can be controlled in nine ways.

[Table] In the evaporator section, the □ mark indicates when the evaporator is in operation, and the ■ mark indicates when it is stopped. Next, a control system for controlling the operation of the air conditioner will be explained based on FIG. 2. The operation control is performed by using a control means 21 consisting of a microcomputer, and the control means 21 has the detection means 18 for detecting the temperature of the blown air and the setting means for setting the temperature of the blown air on the input side of the control means 21. 22 is connected. Further, 23 is an operation switch. Incidentally, the setting means 22 is composed of a variable resistor or the like. Further, on the output side of the control means 21, the
The A and B on-off valves 6 and 7 that control the 1A and 1B evaporators 2 and 3, the three-way valves 20 and 20 that operate the capacity control mechanisms of the compressors 9 and 9, and the reheating each of the on-off valves 15, 15 for controlling the device 10;
It is connected to respective switches 24, 24 which control on/off of the motors M, M of the compressors 9, 9. Although not shown, a switch for controlling the start and stop of the motors of the indoor and outdoor fans 19 and 25 is also connected to the output side of the control means 21. Hereinafter, the operation control of the air conditioner will be explained (cooling operation). This operation control is performed based on a program pre-installed in the control means 21, and is based on the temperature difference (Δt=t- _t0 ) obtained by subtracting the set temperature _t0 from the detected temperature t of the blown air. The temperature of the blown air is controlled to the set temperature t ₀ by increasing or decreasing the capacity level by one step. First, the area classification of the temperature difference Δt, which serves as the reference for the control, will be explained based on FIG. 4. The area is divided into the following five stages. Area a...△t≦-2.5℃ Area b...-2.5℃＜△t≦-1.0℃ Area c...｜△t｜＜1.0℃ Area d...1.0℃≦△t＜2.5℃ Area e... ...2.5°C≦△t The operation control will be explained below based on the flowchart of FIG. 3. B. At startup When the operation switch 23 is closed, the indoor fan 19 and outdoor fan 25 are first driven. Furthermore, although not shown in FIG. 3, the temperature difference △
In response to t, the control means 21 activates the performance stage from one of the second stage, fourth stage, and fifth stage shown in Table 2. In other words, the air conditioner is normally started in the cooling target area E.
This is done in conjunction with the startup of a computer, but since the amount of heat generated by the computer is low at this time, blowing too much cold air will cause problems with condensation on the computer. Even if the temperature difference Δt is in the large region e of 2.5° C. or more, the performance is not set to a very high stage, but starts from the fifth stage described above. In addition, a where the temperature difference Δt is −2.5°C or less,
That is, even when there is no load, taking into account the slow start-up of the natural circulation refrigeration cycle N,
In order to bring the refrigeration cycle N to a steady operating state in advance, the second stage is started. Furthermore, the temperature difference △t is -2.5℃ including zero.
If the temperature is within ranges b, c, and d of +2.5°C, the engine is started from the fourth stage. (b) During normal operation The control means 21 compares the detected temperature t and the set temperature t ₀ at regular intervals, for example, every 3 minutes, and controls the performance level according to the temperature difference Δt. Specifically, if the temperature difference Δt at the comparison point belongs to a region (c, hold region) including the set temperature t ₀ , the air conditioner is maintained at its capacity level at this point. It is. Similarly, when the temperature difference Δt belongs to regions b and a, the capacity step is reduced one step to bring the blown air temperature closer to the set temperature t ₀ . Similarly, when the temperature difference Δt belongs to regions d and e, the capacity step is increased by one step so that the blown air temperature approaches the set temperature t ₀ . As described above, when the capacity level is adjusted based on the temperature difference Δt, except for the following cases, 3
retain that capability level until the next comparison point in minutes,
Simultaneously with the elapse of 3 minutes, the capacity level is adjusted again based on the temperature difference Δt. Therefore, if the temperature difference △t enters the area a during the 3 minutes of the comparison time interval, the capacity level is reduced by one step at that point, and conversely, the temperature difference △t enters the area e. In the case of entering, the capacity level is similarly increased by one step at that point, and if the temperature difference Δt is in areas b, c, and d, the capacity level is maintained as described above. C. At restart: Due to a decrease in the cooling load, the capacity stage drops to the 0th stage shown in Table 2, and both the natural circulation refrigeration cycle N and the compression refrigeration cycle C stop, and then, due to the increase in load, the air conditioning When restarting the apparatus, taking into consideration the slow rise in capacity of the automatic circulation type refrigeration cycle N, the restart is performed from the third stage of the capacity stage, which includes the operation of one compression refrigeration cycle C1. (Not shown in FIG. 3) As described above, the capacity of the natural circulation refrigeration cycle N can be adjusted in two stages, and the capacity of the compression refrigeration cycle C can be adjusted in seven stages, and these Since the capacity control is performed in nine stages in various combinations as shown in Table 2, when starting the air conditioner, even when the temperature difference Δt is large, the air conditioner is operated at partial capacity. This prevents dew build-up on computers, etc. installed in the area to be cooled, and even when the temperature difference △t is negative, only the natural circulation refrigeration cycle N is operated, so that when the natural circulation refrigeration cycle N is started, This reduces the influence of slow start-up, and during normal operation of the air conditioner, the capacity of the air conditioner can be finely adjusted according to the cooling load in the area to be cooled. Control can be performed more precisely, and therefore temperature control of the area to be cooled can also be performed stably. Moreover, when the cooling load decreases, as between the 9th to 3rd capacity stage, and between this 3rd stage and the 2nd to 1st stages below,
Since the capacity of the compression refrigeration cycle C is always prioritized and reduced over the capacity of the natural circulation refrigeration cycle N, the temperature of the blown air can be finely controlled as described above, while power consumption is also reduced. It can be kept to a minimum. In addition, in this embodiment, even in the capacity reduction of the compression refrigeration cycle C, the capacity stage 7
As in the transition from the stage to the sixth stage and from the fourth stage to the third stage, priority is given to the capacity reduction by the capacity control of the compressors 9, 9 over the capacity reduction by the action of the reheater 10, and the This reduces power consumption. Further, in the operation control circuit, as shown in FIG. 6, the detection means 18 consisting of a thermistor
A multi-stage thermostat 30 is provided which connects the thermostat 30 to the setting means 22, and the thermostat 30 is connected to the input of the central processing unit (CPU) in the control means 21 through four signal lines 40, 41, 42, 43. It may also be connected to the side. In this case, the range of the temperature difference Δt and the combinations of signals output from each of the signal lines are shown in Table 3.

[Table] Furthermore, the air temperature used as a reference for controlling the capacity is not limited to the above-mentioned outlet air temperature, but may also be the intake air temperature of the above-mentioned indoor unit 1. (Effects of the Invention) As described above, the present invention provides capacity reducing means for each of the natural circulation refrigeration cycle N and the compression refrigeration cycle C, and the first and second evaporators 2,
3, 11, and 11, and a setting means 22 for setting this air temperature, and the setting set by the setting means 22 from the detected temperature t detected by the detection means 18. temperature
A control means 21 is provided for controlling the operation of the air conditioner based on the temperature difference Δt obtained by subtracting _t0 , and the control means 21 controls the temperature difference Δt to be a predetermined value including zero when starting the air conditioner. Depending on whether it is within the range, exceeds the predetermined range, or is below the predetermined range, the natural circulation refrigeration cycle N is at full capacity and the compression refrigeration cycle C is at the first partial capacity, or the natural circulation refrigeration cycle N is at full capacity. capacity and the compression refrigeration cycle C has a higher capacity than the first partial capacity.
The air conditioner is operated at partial capacity, or the natural circulation refrigeration cycle N is at full capacity and the compression refrigeration cycle C is at zero capacity, and furthermore, during normal operation of the air conditioner, the temperature difference Δt is adjusted at regular intervals. Based on this, the capacity of the air conditioner is increased, maintained, or reduced by one level, and when this reduction is made, the reduction in the capacity of the compression refrigeration cycle C is given priority over the reduction in the capacity of the natural circulation refrigeration cycle N. When starting up the air conditioner, it is possible to prevent dew from condensing on electronic computers, etc., and to reduce the effects of the slow startup of the natural circulation refrigeration cycle N. The capacity of the air conditioner can be finely adjusted according to the cooling load, and the power consumption can also be kept low.

[Brief explanation of the drawing]

Fig. 1 is a refrigerant circuit diagram of an embodiment of the present invention, Fig. 2 is an electric circuit diagram showing a control system of the embodiment, and Fig. 3 is a flowchart showing an operation pattern of the embodiment.
Fig. 4 is an explanatory diagram showing the temperature difference region that is the reference for control in the same embodiment, Fig. 5 is an explanatory diagram showing the inside of the indoor unit of the same embodiment, and Fig. 6 is an explanatory diagram showing the control system of another embodiment. The electric circuit diagram shown in FIG. 7 is an explanatory diagram showing a conventional example. 2, 3...first evaporator, 5...first condenser,
9,9...compressor, 11,11...second evaporator,
12, 12... Second condenser, 13, 13... Pressure reduction means, 18... Detection means, 21... Control means, 2
2...setting means, C...compression refrigeration cycle, N...
...Natural circulation refrigeration cycle.

Claims (1)

[Claims] 1. A natural circulation refrigeration cycle N formed by connecting first evaporators 2 and 3 provided in a cooling target area and a first condenser 5 provided at a higher location, and the first evaporators 2 and 3 A compression refrigeration cycle C consisting of second evaporators 11, 11 installed in parallel with the first condenser 5, second condensers 12, 12 installed in parallel with the first condenser 5, pressure reducing means 13, 13, and compressors 9, 9. In the air conditioner, the natural circulation refrigeration cycle N and the compression refrigeration cycle C are each provided with capacity reducing means, and the temperature of the air flowing through the first and second evaporators 2, 3, 11, and 11 is detected. A detection means 18 and a setting means 22 for setting the air temperature are provided, and based on the temperature difference Δt obtained by subtracting the set temperature t ₀ set by the setting means 22 from the detected temperature t detected by the detection means 18. A control means 21 for controlling the operation of the air conditioner is provided, and the control means 2
1, when the air conditioner is started, the temperature difference △
Depending on whether t is within a predetermined range including zero, exceeds a predetermined range, or is less than a predetermined range, natural circulation refrigeration cycle N is at full capacity and compression refrigeration cycle C is at first partial capacity, or natural circulation The formula refrigeration cycle N is at full capacity and the compression refrigeration cycle C is at a second partial capacity that is higher than the first partial capacity, or the natural circulation refrigeration cycle N is at full capacity and the compression refrigeration cycle C is at zero capacity and air operating the air conditioner, and further increasing, maintaining, or reducing the capacity of the air conditioner by one step based on the temperature difference Δt at regular intervals during normal operation of the air conditioner;
An air conditioner characterized in that, during this reduction, priority is given to reducing the capacity of the compression refrigeration cycle C over reducing the capacity of the natural circulation refrigeration cycle N.