JP3653372B2 - Air conditioning system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an air conditioning system that includes an ice heat storage unit and performs a cooling operation using heat storage by guiding a refrigerant cooled through the ice heat storage unit to an indoor unit.
[0002]
[Prior art]
In general, an ice heat storage unit is provided between the outdoor unit and the indoor unit. For example, during a low power charge period from 10:00 to 8:00 the next morning, liquid refrigerant from the outdoor unit is supplied to the ice heat storage unit. For example, during the daytime when the temperature rises, the liquid refrigerant from the outdoor unit is circulated to the ice heat storage unit to create a supercooled liquid refrigerant. An air conditioning system that supplies a unit to perform a cooling operation using heat storage is known.
[0003]
In this type of air conditioning system, a plurality of outdoor units are connected in parallel in order to increase the refrigeration capacity in accordance with the air conditioning load.
[0004]
[Problems to be solved by the invention]
However, in an air conditioning system equipped with an ice heat storage unit, when multiple outdoor units are connected in parallel, the specifications must be changed, such as whether the number of ice heat storage units is increased or replaced with a large capacity ice heat storage unit. .
[0005]
Then, the objective of this invention is providing the air conditioning system which can eliminate the subject which the prior art mentioned above has, and can connect two or more outdoor units, without changing the capability of an ice thermal storage unit. .
[0006]
[Means for Solving the Problems]
The invention according to claim 1 is an air conditioning system in which an ice heat storage unit is provided between the outdoor unit and the indoor unit so that ice making operation and heat storage use cooling operation can be performed, and a plurality of the outdoor units can be connected. And controlling the valve opening degree of an electronic control valve that controls the amount of refrigerant passing through the ice heat storage tank of the ice heat storage unit, and the refrigeration capacity during the heat storage-based cooling operation is predetermined according to the total refrigeration capacity of the outdoor unit The adjusting means for adjusting the refrigeration capacity increased by the shift rate is provided .
[0007]
According to a second aspect of the present invention, in the first aspect of the present invention, when the total refrigeration capacity of the outdoor unit is equal to or greater than a predetermined capacity, the adjustment means sets the refrigeration capacity during the regenerative cooling operation using the heat storage. The unit is adjusted to a refrigeration capacity that is increased by a constant shift rate based on the total refrigeration capacity of the unit .
[0008]
The invention according to claim 3 is the one according to claim 1 or 2, wherein the adjusting means has a refrigerating capacity at the time of the regenerative cooling operation when the total refrigerating capacity of the outdoor unit is not more than a predetermined capacity. In accordance with the total refrigeration capacity of the outdoor unit, the refrigeration capacity is adjusted to be increased by a predetermined shift rate equal to or higher than a certain shift rate .
[0010]
According to the above invention, since the adjusting means for adjusting the refrigerating capacity at the time of cooling operation using heat storage is provided, even if a plurality of outdoor units are connected and the total refrigerating capacity is changed, the capacity of the ice heat storage unit is changed. It is possible to provide an air conditioning system in which there is no shortage in heat storage capacity without changing the temperature.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0012]
In FIG. 1, reference numerals 100A and 100B denote outdoor units, respectively. A plurality of indoor units 300 are connected to the outdoor units 100 </ b> A and 100 </ b> B via an ice heat storage unit 200. The outdoor units 100A, 100B are provided with three compressors 1A, 1B, 1C, and an outdoor heat exchanger 5 is connected to the compressors 1A, 1B, 1C via a four-way valve 3. 7 is an electronic control valve, 9 is a receiver tank, and 11 is an accumulator. Three outdoor heat exchangers 43, 45, 47 are connected in parallel to the outdoor heat exchanger 5 via an ice heat storage unit 200. 44, 46 and 48 are electronic control valves whose opening degree is set according to the air conditioning load. The ice heat storage unit 200 is provided with a receiver tank 15, an ice heat storage tank 17, an electronic control valve MV1, and electric switching valves SV1, SV2, SV3, SV4. E1, E2, and E3 are temperature sensors.
[0013]
The refrigerant circuit according to the present embodiment will be described together with the operation.
[0014]
Ice making operation For example, during a low power bill period from 10:00 to 8:00 the next morning, liquid refrigerant from the outdoor heat exchanger 5 is supplied to the ice heat storage tank 17 to produce ice in the heat storage tank 17. The cold energy stored in the heat storage tank 17 is used for daytime cooling operation as described later.
[0015]
In this case, as shown in FIG. 1, the electric switching valves SV1 and SV4 in the ice heat storage unit 200 are closed, and the electronic control valve MV1 and the electric switching valve SV2 (SV3) are opened. According to this, the refrigerant from the compressors 1A, 1B, 1C passes through the outdoor heat exchanger 5 as indicated by solid arrows, then flows into the ice heat storage tank 17 through the electronic control valve MV1, and after passing through the ice heat storage tank 17 Then, it flows into the gas pipe 29 through the open electric switching valve SV2 (SV3), and is returned to the compressors 1A, 1B, and 1C through the four-way valve 3 and the accumulator 11. In this case, excess liquid refrigerant is stored in the receiver tank 15.
[0016]
That is, during the ice making operation, the indoor heat exchangers 43, 45, and 47 are bypassed, and the refrigerant is evaporated in the ice heat storage tank 17, and the ice making operation is performed in the ice heat storage tank 17. The controller 50 controls the opening and closing of the various valves.
[0017]
Cooling operation using heat storage For example, during the daytime, when the temperature rises, the liquid refrigerant from the outdoor heat exchanger 5 is circulated to the ice heat storage tank 17 to produce a supercooled liquid refrigerant. The liquid refrigerant is supplied to the indoor heat exchangers 43, 45, 47, and the regenerative cooling operation is performed.
[0018]
In this case, as shown in FIG. 2, the electric switching valves SV2 and SV3 in the ice heat storage unit 200 are closed, and the electric switching valves SV1 and SV4 (electronic control valve MV1 as necessary) are opened. According to this, after the refrigerant from the compressors 1A, 1B and 1C passes through the outdoor heat exchanger 5 as indicated by solid arrows, flows into the ice heat storage tank 17 through the electric switching valve SV1, and after passing through the ice heat storage tank 17 The refrigerant flows into the indoor heat exchangers 43, 45, 47 through the electric switching valve SV4 and the electronic control valves 44, 46, 48, and the refrigerant that has passed through the indoor heat exchangers 43, 45, 47 is compressed through the gas pipe 29, the four-way valve 3. Returned to machine 1A, 1B, 1C. The controller 50 controls the opening and closing of the various valves.
[0019]
That is, during the cooling operation using the heat storage, the refrigerant is supplied to the indoor heat exchangers 43, 45, 47 after being cooled in the ice heat storage tank 17 by the cold heat stored by the ice making operation described above. The ability of
[0020]
Next, opening / closing control of the electronic control valve MV1 will be described.
[0021]
When any one of the indoor heat exchangers 43, 45, 47 is unloaded during the above-described heat storage-use cooling operation, the electronic control valves 44, 46, 46 of the indoor heat exchangers 43, 45, 47 to be unloaded are used. The opening of 48 is reduced via the controller 50. That is, in the normal cooling operation (non-heat storage cooling operation) control other than the heat storage use cooling operation, the coil temperature (evaporation temperature) E2 of the indoor heat exchangers 43, 45, 47 and the inlets of the indoor heat exchangers 43, 45, 47 are used. Since the opening degree of the electronic control valves 44, 46, and 48 is controlled through the controller 50 so that the difference from the temperature E1 (= E2-E1) becomes a predetermined temperature difference, the evaporation temperature E2 becomes high during the unloading operation. In order to increase the inlet temperature E1 by that amount, control is performed to reduce the supply amount of the refrigerant.
[0022]
In this case, if the supercooled refrigerant continues to be supplied to the indoor heat exchangers 43, 45, 47 that are unloaded from the ice heat storage tank 17, the refrigerant temperature E3 at the outlet of the ice heat storage tank 17 is increased. The evaporation temperature may be lower than E2.
[0023]
When the refrigerant temperature E3 is lowered, the inlet temperature E1 of the indoor heat exchangers 43, 45, 47 is inevitably lowered, so that the coil heat (evaporation temperature) E2 of the indoor heat exchangers 43, 45, 47 and the indoor heat exchange are performed. Since the difference (= E2−E1) from the inlet temperature E1 of the chambers 43, 45, and 47 becomes larger than a predetermined temperature difference, the opening degree of the electronic control valves 44, 46, and 48 is increased in accordance with the normal cooling operation control. Is done.
[0024]
In short, if this state is left unattended, the electronic control valves 44, 46, and 48 respond to the so-called reverse response to increase the flow rate in the unload operation, where the control for reducing the flow rate should be performed. As a result, refrigerant evaporation in the indoor heat exchangers 43, 45, 47 becomes insufficient, resulting in a problem of compressor liquid back.
[0025]
In order to prevent this, when the refrigerant temperature E3 at the outlet of the ice heat storage tank 17 becomes lower than the evaporation temperature E2, the opening degree of the electronic control valve MV1 in the ice heat storage unit 200 in the fully closed state is appropriately opened. The reverse response of the so-called electronic control valves 44, 46, and 48 is avoided by combining the refrigerant from the outdoor heat exchanger 5 with the supercooled refrigerant and increasing the temperature E3 of the refrigerant.
[0026]
According to this embodiment, a plurality of outdoor units can be connected. In the example of FIG. 1, two outdoor units 100A and 100B are connected in parallel, but the number of connected units can be changed. That is, for example, three or four or more outdoor units are connected according to the air conditioning load. Normally, the capacity of the ice heat storage unit 200 is changed according to the number of outdoor units connected.
[0027]
In this embodiment, without changing the capacity of the ice heat storage unit 200, supercooling control is performed to change the refrigeration capacity during the heat storage-based cooling operation.
[0028]
In a normal cooling operation (non-heat storage cooling operation) that is not a heat storage-based cooling operation, a refrigerating capacity E0 according to the total horsepower of the outdoor unit 100 is obtained as shown by a dotted line in FIG. In order to increase the refrigerating capacity E0, it is necessary to increase the degree of supercooling SC. In this embodiment, the degree of supercooling SC is increased by reducing the opening of the electronic control valve MV1 (FIG. 2) in the ice heat storage unit 200.
[0029]
When the opening degree of the electronic control valve MV1 is reduced, for example, as shown by a thin line, the supercooling degree becomes SC1, the refrigeration capacity increases by E1, and the refrigeration capacity in this case becomes E1 + E0. When the degree of increase in the refrigerating capacity with respect to the refrigerating capacity E0 (hereinafter referred to as “shift rate”) is seen, the following equation is obtained.
[0030]
Shift rate = (E1 + E0) / E0 (1)
For example, when the opening degree of the electronic control valve MV1 is greatly reduced, the degree of supercooling becomes SC2 as indicated by the thick line, the refrigeration capacity increases by E2, and the refrigeration capacity in this case becomes E2 + E0. Looking at the shift rate with respect to the refrigerating capacity E0 described above, the following equation is obtained.
[0031]
Shift rate = (E2 + E0) / E0 (2)
In this embodiment, by controlling the temperature difference ΔTn shown in FIG. 3, for example, the shift rate shown in the equations (1) and (2) is controlled. Control of this shift rate is governed by the controller ("adjusting means") 50 described above.
[0032]
Assume that the number of outdoor units connected changes, and the total refrigeration capacity of the outdoor units changes between 14 to 30 horsepower as shown in FIG.
[0033]
In this embodiment, when the total refrigeration capacity of the outdoor unit is equal to or greater than a predetermined capacity (for example, 20 horsepower), the refrigeration capacity during the cooling operation using the heat storage (corresponding to the indoor unit capacity) is based on the total refrigeration capacity of the outdoor unit. Thus, the refrigeration capacity is increased by a certain shift rate (for example, 25%). For example, when the total refrigeration capacity of the outdoor unit is 24 hp, the refrigeration capacity during the cooling operation using heat storage is refrigeration capacity of 30 hp increased by a constant shift rate of 25% based on the total refrigeration capacity of 24 hp of the outdoor unit. When the total refrigeration capacity of the outdoor unit is adjusted to 30 horsepower, the refrigeration capacity at the time of cooling operation using heat storage is increased by a constant shift rate of 25% based on the total refrigeration capacity of 30 hp of the outdoor unit 37 Adjusted to 5 horsepower.
[0034]
In this control, assuming that the compressors 1A, 1B, and 1C are operated 100%, the maximum time for which heat storage can be used is gradually reduced as shown in FIG. 4, and when the total refrigeration capacity of the outdoor unit is 30 horsepower, 7.1 Decrease to 1 hour.
[0035]
In this embodiment, the capacity of the ice heat storage unit 200 is set so as to correspond to the total refrigeration capacity 20 horsepower (predetermined capacity) of the outdoor unit.
[0036]
Therefore, the maximum time for which heat storage can be used has been reduced to 7.1 hours because when the outdoor unit has a total refrigeration capacity of 30 horsepower, the capacity of the ice storage unit 200 is greatly insufficient with respect to the total refrigeration capacity of the outdoor unit. Because it does. If the maximum time available for heat storage is too short on the air conditioning system at 7.1 hours, it is desirable to extend the maximum time by setting the shift rate 25% small.
[0037]
In this embodiment, when the total refrigeration capacity of the outdoor unit is less than or equal to a predetermined capacity (for example, 20 horsepower), the refrigeration capacity at the time of cooling operation using heat storage (corresponding to the indoor unit capacity) depends on the total refrigeration capacity of the outdoor unit. The refrigeration capacity is adjusted to be increased by a predetermined shift rate equal to or higher than a certain shift rate (eg, 25%). For example, when the total refrigeration capacity of the outdoor unit is 18 hp, the refrigeration capacity during cooling operation using heat storage is increased by a predetermined shift ratio of 28%, which is a constant shift ratio of 25% or more, according to the total refrigeration capacity of the outdoor unit of 18 hp. When the outdoor unit's total refrigeration capacity is 14 hp, the refrigeration capacity during the regenerative cooling operation is a constant shift rate of 25% or more according to the total refrigeration capacity of the outdoor unit 14 hp. The refrigeration capacity is increased to 19 horsepower increased by a predetermined shift rate of 35%.
[0038]
When the total refrigeration capacity of the outdoor unit is less than or equal to a predetermined capacity, this combination leaves the capacity of the ice heat storage unit 200 with respect to the total refrigeration capacity of the outdoor unit. In this embodiment, as described above, the amount of surplus heat storage can be maximized by shifting it to a constant shift rate of 25% or more, so that the refrigerating capacity during the heat storage cooling operation can be increased.
[0039]
In the above embodiment, since the ice heat storage unit 200 is limited to one and a plurality of outdoor units can be connected, the effect of easily constructing an air conditioning system according to the air conditioning load, etc. Is obtained.
[0040]
【The invention's effect】
According to the present invention, a plurality of outdoor units can be connected without changing the capacity of the ice heat storage unit.
[Brief description of the drawings]
FIG. 1 is a circuit diagram showing an embodiment of the present invention.
FIG. 2 is a circuit diagram during cooling operation using heat storage.
FIG. 3 is a diagram illustrating a shift rate.
FIG. 4 is a diagram for explaining heat storage utilization time.
[Explanation of symbols]
1A, 1B, 1C Compressor 3 Four-way valve 5 Outdoor heat exchanger 17 Ice heat storage tank 50 Controller (Adjustment means)
MV1 Electronic control valve SV1, SV2, SV3, SV4 Electric switching valve 100A, 100B Outdoor unit 200 Ice heat storage unit 300 Indoor unit

Claims (3)

In an air conditioning system that provides an ice heat storage unit between an outdoor unit and an indoor unit, and enables ice-making operation and heat storage-use cooling operation,
A plurality of the outdoor units are formed to be connectable,
Controls the valve opening of an electronic control valve that controls the amount of refrigerant passing through the ice heat storage tank of the ice heat storage unit, and shifts the refrigeration capacity during the heat storage-based cooling operation by a predetermined amount according to the total refrigeration capacity of the outdoor unit An air conditioning system comprising an adjusting means for adjusting the refrigeration capacity increased by a rate. When the total refrigeration capacity of the outdoor unit is greater than or equal to a predetermined capacity, the adjusting means increases the refrigeration capacity during the heat storage-based cooling operation by a fixed shift rate based on the total refrigeration capacity of the outdoor unit. The air conditioning system according to claim 1, wherein the air conditioning system is adjusted. When the total refrigeration capacity of the outdoor unit is less than or equal to a predetermined capacity, the adjustment means increases the refrigeration capacity during the heat storage-based cooling operation by a predetermined shift rate equal to or greater than a certain shift rate according to the total refrigeration capacity of the outdoor unit. It adjusts to the refrigerating capacity made to adjust, The air conditioning system of Claim 1 or 2 characterized by the above-mentioned.

Images