AU2015282149A1

AU2015282149A1 - Chiller system

Info

Publication number: AU2015282149A1
Application number: AU2015282149A
Authority: AU
Inventors: Hirotaka Nakamura; Hiroyuki Nishi; Yuichiro Tanaka
Original assignee: Yanmar Co Ltd
Current assignee: Yanmar Power Technology Co Ltd
Priority date: 2014-06-24
Filing date: 2015-05-15
Publication date: 2017-02-02
Anticipated expiration: 2035-05-15
Also published as: CN106461281B; WO2015198741A1; JP6355987B2; JP2016008773A; EP3163219B1; AU2015282149B2; EP3163219B8; CN106461281A; EP3163219A4; EP3163219A1; KR20160146909A

Abstract

A chiller system configured by connecting a plurality of heat pump type chillers which regulate the temperature of a circulation fluid for temperature control as a heating medium by way of the heat of condensation or the heat of vaporization of a refrigerant, wherein, if a chiller from among the plurality of chillers is operating, an operation command is transmitted to one of the stopped chillers when the relationship of [Total Demand Operating Capacity] / ([Current Number of Operating Units] + 1) ≥ [Partial Load Capacity] is satisfied, where: [Total Demand Operating Capacity] is the total operating capacity demanded by the chillers that are operating; [Current Number of Operating Units] is the number of chillers in operation; and [Partial Load Capacity] is the load capacity of a prescribed partial load.

Description

DESCRIPTION

Title of Invention CHILLER SYSTEM

Technical Field [0001]

The present invention relates to a chiller system in which a plurality of heat pump chillers is connected to each other, the chillers regulating a temperature of a circulating liquid as a heat medium for temperature regulation by condensation heat or evaporation heat of a refrigerant.

Background Art [0002] A chiller system in which a plurality of heat pump chillers is connected to each other is conventionally known, where the chillers ar’e to regulate the tem.pera.ture of a circulating liquid as a heat medium for regulating the temperature (for example, for air conditioning) by condensation heat or evaporation heat of a refrigerant (for example, see Patent Document l).

In such a chiller system, generally, the number of chillers to be operated is increased/decreased, out of the plurality of chillers, according to a required load capacity. In this case, it is desired to level respective cumulative operation times of the chillers by not· operating particular chillers unevenly but operating each chiller evenly, from the viewpoint that it is preferable to perform maintenance on the plurality of chillers at the same time, [0004] PCTYA091 (P010856WO01) 1/54

In this regard, Patent Document: 1 discloses a. configuration In which control I» carried out so that a plurality of chilling units (chillers) is operated in rotation based .on the number of times of thermo.-ON (the number of times of thermo-ON at which; a compressor is driven) for each chiller, for the purpose of levelling an actual operation time (cumulative operation time) of each of the chillers.

Prior Art Document Patent Document: [0005] [Patent Document ij JP H10-1226.04Jl

Summary of Invention Problem to Be Solved, by Invention [0006]

However, in the chiller system, described In Patent Document 1, when the load capacity is increased, a newly active chiller Is added after the operation capacity of each, of the current active chillers reaches 100¾ Output (rated output) (see paragraphs [0073]-{Q075] of the Patent Document l)i Thus, when a partial load, at which the operation output does not reach the rated output of the chiller is continuously applied, no: newly active chiller is added while such a -.partial load is being: continuously applied- As a result, the respective: cumulative operation times: of the: chillers are likely to vary largely., [0007:]

In consideration of the above circumstances, an object of the present Invention, is to provide a chiller system in which a plurality of heat; pump chillers Is connected to each other, the chiller system capable of leveling respective cumulative operation times of the chillers even when a partial load at which an operation output does not reach a rated Output of the chiller is continuously applied. PCTYA09J (PC I085677():) i) · 2/54

Means for Solving Problem E:DQ08]:

In order to resolve the above problem* the present invention '5 provides a chiller system including a plurality of heat pump1 hhillers being: connected: to each other,, the plurality of 'heat pump Chillers regulating a temperature of a circulating; liquid as a heat medium for temperature regulation by condensation heat or evaporation: heat of a refrigerant. When there is at least one active1 chiller out of the IQ plurality of chillers, ah operation command is transmitted, to one of the remaining chillers being stopped, under a condition that the following relation is satisfied; [total required operation capacity] J ([number of currently active chillers] 4- 1) > [partial load capacity], where the [total required operation capacity] represents a total operation capacity ϊ:δ required of the at least one active chiller, the [number of currently active chillers] represents the number of the at least one active chiller, and the [partial load capacity] represents a load capacity of a. prsdeterniiiied [0009] 20 In an exemplary aspect of the preseat invention, the plurality of chillers is each capable of being in a normal state, an alarming State in which an alarm is being transmitted, or a befbre~alarming state that is a state: between the normal state and the: alarming state, A target chiller for a next operation command is selected in the order of- an active; chiller 25 in the before-alarming state; a stopped chiller in the before-alarming State; an active chiller in the normal state*"and a stopped chiller in the normal state. When the chillers are in the: same state, the target chiller for the next operation command is selected in ascending order of a cumulative output amount from an initial state or from a time point at 30 which a predetermined maintenance has been performed. PCTm091 (M108S6WO01): * 3/5-1 [DO IQ]

In an exemplary aspect of the present Invention, when there: is at least one: active chiller out of the plurality of chillers, a stop command is transmitted to one of the at least one active chiller under a condition B that the following relation is satisfied' [total required operation capacity] / [number of currently active chillers] < [partial load capacity], [00113

In an exemplary aspect of the present invention, the plurality of chillers is each capable of being in the normal state, the alarming state 10 in which an alarm is being transmitted, or the before * alapaing state that is a state between the normal state and the alarming state. A target chiller for a next stop command is selected in the order of· a stopped chiller In the normal State; an active chiller in the normal state! a stopped chiller in the before-alarming state; and an active chiller in the 15 befpre-alarming state. When the chillers are in the same state, the target chiller for the next stop command is selected in descending order of the cumulative output amount from the initial state or from the time point at which a predetermined maintenance has been performed. 20 Effects of Invention [0012]

With the present invention providing a chiller system in which a plurality of heat pump chillers is connected to each other, it is possible to level respective cumulative operation times of the chillers even when a 25 partial load at which an operation output does not reach a rated output is continuously applied.

Brief Description of Drawings [0013] 30 [FIG. li BCTYAG91 (PG10856WQ01) - 4/54 FIG. 1 is a system diagram showing a schematic configuration of a chiller system according to an embodiment of the present invention. [FIG. 2} FIG.. 2 is a schematic block diagram showing one chiller in the 5: chiller system.

[FIG. 3] FIG, 3 Is a schematic block diagram showing a chiller that performs a cooling operation.

[FIG. 4] 10 FIG·, 4 is a schematic block diagram showing a chiller that performs a heating operation.

[FIG. 5] FIG. 5 is a schematic block diagram showing a chiller that performs, a defrost operation. 1:5 [FIG, 6] FIG. 6 is a graph indicating a control operation performed by a master chiller on each chiller in the chiller system in which the; number of the chillers is set to eight.

[FIG. 7]: 2Q FIG, 7 is a flowchart indicating steps of one example of the control operation by the master chiller on each chiller so as to control the number: of active chillers,.

[FIG. 8] FIG. 8 is a table for determining the priority of the chillers when 25 increasing/decreasing the number of active chillers.

Modes: for Carrying· out Invention [0014]

Hereinafter, an embodiment according to the present invention 30 willbe described with reference to the drawings. PCT¥A(m CFO10856WO 01) - 5/54 FIG. 1 is a system diagram showing; ;a schematic configuration of a chiller system 1 according to an embodiment of the present invention. [0016]

In the chiller system 1 shown in FIG. I, a plurality pf heat pump chillers 100 is connected in parallel Hereinafter, a heat pump chiller is occasionally referred to, simply, as a chiller.

[0017]

Specifically* the chiller system 1 includes: the plurality of chillers 100 (!) to 100 (n) (n is an integer of > 2); and a circulating liquid circuit 200, Each of the chillers 100 (l) to 100 in) has the same configuration. Accordingly, the rated output for each of the chillers 100 (:.1): to 100 (n) is set to the same value. Hereinafter, each of the chillers 100 (l) to 100 (a): is occasionally indicated simply with the reference numeral 100.

[0018]

The chiller system 1 further includes: the: circulating liquid circuit 200 that is installed in a temperature regulation target area (for example, an. air conditioning target area, not shown) for circulating a circulating liquid as a heat medium for temperature regulation (for example,, for air conditioning); and circulation pumps 800 (l) to 300 (n) respectively disposed corresponding to the chillers 100 (l) to 100 (n) in the circulating liquid circuit 200 so as to circulate the circulating: liquid in the circulating liquid circuit 200. The circulation pumps 300 (l) to 300 (n) regulate the temperature of the circulating liquid that, flows in the circulating liquid circuit· 200. Here, any circulating liquid can he used provided that it serves as the heat medium, and representative examples thereof include water. However, the cireulating liquid is not limited thereto. For example, water containing antifreeze liquid can he used.

[0019]

The circulating liquid circuit 200 is constituted by: an inlet main PCTYA091 CP010856W001) - 6/5d pipe 210 to. flow the circulating liquid toward the plurality of chillefslOO (l) to 100 (n); inlet Maned pipes 211 (l) to: 211: (n): to divide arid flow the circulating liquid from the inlet main: pipe 2:10 into the respective chillers 100 v 1) to 100 in); an outlet: main pipe 22Q: to flow the circulating liquid out of the plurality of chillers 100 :(.1). to 100 (n); and outlet branch pipes 221 (1) to 221 in) to flow and join the circulating liquid from the plurality of chillers 100 |l) to 100 in) to the outlet main pipe 220, [0020] 'Specifically; the inlet branch pipes 211 Cl) to 211 (n) each connect a branch portion of the inlet main pipe 210 that corresponds to each chiller 100 ll) to 100 (n) and a circulating: liquid flowing-in side of each chiller 100 (1) to 100 fn), The outlet branch pipes 221 (l) to 221 (n) each connect a circulating liquid flowing-out side of each chiller 100 (l) to 100 (η) and a confluence portion of the outlet main pipe 220 that corresponds to each chiller 100 (l) to 100; in), G)n one side of each pair of the inlet branch pipes 211 Cl) to 211 in) and the outlet branch pipe 221 (1; to 221 (n) (in this: example:, on the side of the outlet branch pipes 221 (l) to 221 in)), each circulation pump 300 (l) tq 800 (n) is; disposed to circulate the circulating liquid in the: circulating liquid circuit 200.

[0021]

In the chiller System. 1 having the above configuration, the circulating liquid that is circulated by the circulation pumps; 300 (Id to 80Q: .(h) is divided and flows, from the; inlet main pipe 210, into each chiller 100 (1) to 100 (n) via each inlet branch pipe 211 (.1.) to 211: (n). and the temperature of the: circulating liquid is regulated by each chiller 100' (1) to 100 (n), The circulating liquid whose temperature is regulated is joined, from each chiller 100 (1) to 100 in), to the outlet main pipe 22(3 via each outlet branch pipe 221 (l) to 221 (n), and is circulated in the temperature regulation target area (for example, the air conditioning target area) of the circulating liquid circuit 200. The; respective load PCTYA091 (POIQBSeWOOl) - 7/54 sides ox the inlet main pipe 210 and the outlet main pipe 220: are connected to each other* &r example, via a heat exchanger not shown, and constitute a closed circuit, [0022] :5 ΙΊΟ. 2 is a schematic block diagram showing one chiller 100 in the chiller system i. Note that FIG. 2 shows one inlet branch pipe 211 out of the inlet branch pipes 211 (l) to 211 (n), one outlet branch pipe 221 out of the outlet branch pipes 221 (l> to 221 (h), and one circulation pump 300 out of the circulationpumps 300 (l) to BOO (n). 10 [0023]

The chiller 100 drives a compressor 10 that compresses: a refrigerant so as to regulate the: temperature of the cireuiafing liquid by the condensation heat or the evaporation, heat of the refrigerant.

[0024] p That is, the chiller 100 includes; the compressor 10 that sucks and discharges the refrigerant: a refrigerant'air heat exchanger 20 that exchanges heat between the refrigerant and air frpeeifically, outside airh a refrigerant-air heat exchanger fan 30 for the refrigerant-air heat exchanger 20: an expansion valve 40 that expands the refrigerant 2Q compressed by the compressor IQ; a refrigeranfreir opiating liquid heat exchanger 50 that exchanges heat between the circulating liquid and the refrigerant: an engine 60 that drives the compressor 10; and an engine exhaust heat recovery unit 70 that recovers exhaust heat of: the engine 60. The chiller 100 is capable of executing a heating operation, a 25 cooling operation and a defrost operation as described later. In this example, the expansion valve 40 is eonsfituted by a closahlo first expansion valve 41 and a cldsaMe second expansion valve 42.

[0025]

The compressor 10 may he constituted hy a plurality of 30 compressors connected in parallel. Also, the refrigerant-air boat PGTYA091 (P010856V/O 01) - 8/64 exchanger 2# may be constituted, fay a plurality of reMgerant'air heat exchangers connected in. parallel, [0026]

Specifically, the chiller 100 further includes: a refrigerant Circuit 5 110 to circulate the refrigerant; a coolant path 120 to circulate an engine coolant for cooling the engind 60l a circulation pump 180· lor 'the coolant path 120» and & control device 140.

[0027]

In the refrigerant circuit 110, the compressor 10, the Refrigerant* 10 air heat: exchanger 20» the re&igerant'circulating liquid heat exchanger 50:» the expansion Valve 40 and the engine exhaust heat recovery unit 70 are disposed.

[0028]

The refrigerant circuit 110 includes: a four-way valve 111; a 15 bridge circuit 112; a high pressure gas refrigerant path 113a· a first low pressure gas refrigerant path 113b; a first gas refrigerant path 113 c; a first refrigerant path 113d; a high pressure liquid Refrigerant path USel a. first low pressure gas-liquid two phase: refrigerant path T13f; a second refrigerant path 113g; a second gas refrigerant path 113h; a second low 20 pressure gas-liquid two phase refrigerant path II 3i; and a second low pressure gas refrigerant path XI,3j.

[00291

The four-way valve 111 is: switched, in response to an instruction signal from the control device: 140:, between a first connection state (state 25 shown in PIG. 2) In which an inlet (lower side in PIG, 2) is.: connected' to one connection port (left side in PIG. 2) and furthermore the: other connection, port (right side in PIG. 2) is connected to an outlet (upper Side in FIG, 2:), and a second connection state In which the inlet· is connected to the other connection port and furthermore the one 30 connection, port is connected to the outlet. Thus, the four-way valve 111 PCTmDSl (TO 1()866WO01) * 9/54 can switch the flowing direction: ef the refrigerant.

[0030]

The bridge circuit 112. -includes four check valves :(a first check, valve: 112a, a second check valve 112b, a third check valve 112c and a 5 fourth check valve 112d), and is constituted by a first check valve line 1121 including Wo Cheek valves (the first cheek valve 112a and the second cheek valve 112b) and a second check valve line 1122 including the remaining two check valves (the third check valve 112c and the fourth check valve 112d). 10 [0031]

The first cheek valve line 1121 is constituted by the first check valve 112a and the second check valve 112b that are connected in series so that the refrigerant flows: in the same direction. The second check valve line 1122 is constituted by the third check valve 112c. and the 15 fourth check valve 112d that are connected in series so that the refrigerant flows in the same direction, Furthermore, the first check valve line 1121 and the second check valve line 1122 are connected in parallel so that the refrigerant flows in the same direction.

[0032] 2:0 In the bridge circuit 112, a connection point; between the first check valve 112a and the second, check valve 112h is referred to as a first intermediate connection point Fl, a connection point between the first cheek valve 112a and the third check valve 112c is referred to as an Outlet connection point Ρ% a connection point between the third check 25 valve 11 lb and the fourth check valve- .112d is referred to as a second intermediate connection point P3, and a connection point between the second check valve 112b and the fourth check valve :112d is referred to as an inlet connection point P4.

[0033] 30

The high pressure gas refrigerant path 113a connects a discharge PCTYA091 (P01Q856WO0I) - 10/54 port of tile compressor 10 and the inlet of the feur-way valve 111. The first low pressure gas refrigerant path 113b connects the outlet of the four-way waive 111 and a suction port of the compressor 10. The first gas refrigerant path 111c connects the one connection port of the four' 5 way valve 111 and one connection port of the refrigerant-air heat exchanger 20, The first refrigefaht path 1133 connects the other connection port of the refrigerant-air heat exchanger 20 and the first intermediate connection point PI of the bridge circuit 112. The high pressure liquid refrigerant path I13e connects the outlet connection IP point F2 of the bridge circuit 112 and one side of the expansion valve 40 (specifically the first expansion valve 41 and the second expansion valve 42). The first low pressure gas-liquid two phase refrigerant; path llSf connects the other side of the first expansion valve 41 constituting the expansion valve 40 and the inlet connection point P4 of the bridge circuit 15 112. The second refrigerant path II 3;g connects the second intermediate connection point P3 of the bridge circuit 112 and one refrigerant connection port of the refrigerant-circulating liquid heat exchanger :50. The second gas refrigerant path 113h connects the other refrigerant connection port of the refiigerant-eirculatmg liquid heat exchanger SO 26 and the other connection port of the four-way valve 111. The second low pressure gaqdiqmd two phase refrigerant path llli connects the other side of the second expansion Valve 42 constituting the expansion valve 40 and a refrigerant inlet of the engine exhaust heat recovery unit 10, The second low pressure gas refrigerant path 113j connects a refrigerant 25 outlet of the: engine exhaust heat recovery unit 70 and a confluence point P5 located in the middle of the first low pressure gas refrigerant path 113b. In the first low pressure gas refrigerant path 113b,: the downstream side of the confluence point P5 (the side of the compressor 10) is referred to as a confluence path llSbl. 30 [0034] PCOT091 (POiOSSOWOOl) - 11/54

The respective. opehing degrees of the first expansion valve 41 and the second expansion valve 42 can be adjusted in response to the instruction signal from the control device 140. Thus, the amount of the refrigerant circulating in the refrigerant circuit 110 can be adjusted by 5 the first expansion valve 41 and. the second expansion valve 42, Specifically; the first expansion valve 41 and the: second expansion valve 42 are configured by connecting a plurality of eldsable expansion valves in parallel. In this way, the first expansion valve 41 and the second expansion valve 42 can adjust the amount of the refrigerant: circulating 10 in the refrigerant circuit 110 by being combined as the expansion valve(s) to be opened.

[0035]

In this embodiment, the chiller 100 further includes an oil separator 81, an accumulator 82 and,a receiver; 83. 15 [0036]

The oil separator 81 is disposed in the high pressure gas fefeigeraat path 113a, and separates a lubricant oil of the compressor 10 contained in the refrigerant so as to return the separated lubricant oil to the compressor 10 via a valve 81a (more specifically, a solenoid valve), 20 The accumulator 82 is disposed in the eohfiuenee path 113b 1 of the first low pressure gas refrigerant path 113b, and separates the liquid refrigerant that has not been completely evaporated by the refrigerant-circulating liquid heat .exchanger 50: serving as an evaporator or by the refrigerant-air heat exchanger 20 serving, as an evaporator. The 25 receiver 83 is disposed in the high pressure liquid refrigerant path 113e, and temporarily stores the high pressure liquid refrigerant from the bridge circuit 112, [00873

The coolant path 120 constitutes the path for the engine coolant 30 that cools the engine 60> and includes a first thermostat type switching PCTYMJ91 iP01(B56WO0!) - 12/54 valve 12:1, a second thermostat type switching valve 122, a radiator 128, an outlet path 124a, an inlet path !24b>·. and a first path 1240 to a fifth path 124gi [0038] δ The outlet path 124a connects an outlet of the engine 60 and an inlet (lower side in FIG. 2) of the first thermostat type switching valve 121, The inlet path 124b connects an outlet of the radiator 123 and an inlet of the engine 60. The first path 124c connects one outlet (upper side in FIG. 2) of the first thermostat type switching valve 121 and an 10 inlet (left side in FIG. 2; of the second thermostat type switching valve 122. The second path 124d connects the other outlet (right side in FIG. 2} of the first thermostat type switching valve 121 and an inlet of the radiator 123. The third path 124e connects one outlet (upper side in FIG. 2) of the second thermostat type switching valve 122 and a coolant αι 15 inlet of the engine exhaust: heat recovery unit 70. The fourth path I24f connects the other outlet (right side in FIG, 2) of the second thermostat type switching valve 122 and a confluence point B6 located in the middle of the inlet path 124b. The fifth path 124g connects a coolant outlet of the engine exhaust heat recovery unit 70 and a confluence point P7 20 located upstream of the confluence point P6 of the inlet path 124b. The circulation pump 130 is disposed in the inlet path 124b, between the inlet of the engine 60 and the confluence point P6. The circulation pump 130 circulates the engine coolant in the coolant path 120 in response to the instruction signal from the control device 140. The engine exhaust heat recovery unit 70 belongs to both of the refrigerant circuit: 110 and the; coolant path 120.

[00391

The first thermostat type switching valve 121 flows the engine coolant from the engine 60 toward the second thermostat type switching 30 valve 122 when the temperature of the engine coolant is less than a B0TO.091 (P010856WO0 i) - 13i54 predetermined first temperature (for example, 71°0). On the other hand, the first thermostat type switching valve 121 flows the engine coolant from the engine 60 toward the radiator 123 when the temperature of the engine coolant is not less than the first temperature. Thus, the coolant path 120 can circulate the engine coolant toward the second thermostat type switching valve: 122 when the temperature of the: engine coolant is: less than the first temperature, while it can circulate: the engine coolant toward the radiator 128 when, the temperature of the engine coolant, is not less than the first temperature, [0040]

The second thermostat type switching valve 1,22: flows the engine coolant from the first thermostat type switching valve 1:2:1 toward both of the engine exhaust: heat recovery Unit 70 and the.: confluenee point P6 of the inlet path 124b when the temperature of the engine coolant: is less than a predetermined second temperature (for example,; 60°C) that i& lower than the first temperature. On the other hand, the: second thermostat type switching valve 122 flows the engine coolant from the first thermostat; type switching valve 121 toward the engine exhaust heat recovery unit 70 when the temperature of the engine -coolant, is not less than the second temperature. Thus, the coolant path 120 can circulate the engine coolant toward both of the engine exhaust heat recovery unit 70 and the confluence, point P6 of the inlet path 124b when the temperature of the engine coolant is less than the second temperature, while it can circulate the engine coolant toward the engine exhaust heat recovery unit 70. When the temperature of the engine coolant is not less than the second temperature hut less than the first temperature.

[004¾]

The; temperature of the engine Coolant can he detected by a temperature sensor (not shown) disposed in the coolant: path 120.

[0042] PCTYA091 CP0I0856WQQ l) - 14/5.4 file inlet branch pipe .211, which is a part of the circulating liquid circuit 200, connects a circulating liquid inlet: of the refrigerant· circulating liquid heat exchanger 50: and a branch portion of the inlet main pipe 210 (see FIG. 1) corresponding to the chiller 100, The outlet branch pipe 221, which is a part of the circulating liquid circuit 200, connects a circulating liquid Outlet of the refrigeinnt'Circulatmg liquid heat exchanger 50 and a confluence portion of the outlet main pipe 220: (see: FIG. 1,) corresponding to the chiller 100. The refrigerant-circulating liquid heat exchanger 50 belongs to: hoth of the refrigerant circuit 110 and the circulating liquid: circuit 200, [0043]

The compressor 10 is conneGtod to the engine 60 via a clutch 11. The clutch 11 switches, in response to the instruction signal from the control device 140, between a connection state in which the drive force is transmitted from the engine 60 to the compressor 10 and a block state in which the transmission of the drive force from the engine 60 to the compressor 10 is blocked, 10044]

The chiller 100 further includes a first pressure sensor 151, a first temperature sensor 161, a second pressure sensor 15¾ a second temperature sensor 162 and a rotation speed sensor 170.

[00451

The first pressure sensor 151 and the first temperature sensor 161 are disposed in the confluence path iX3bl, and detect respectively the pressure and the temperature of the refrigerant in the eonfiuenee path 11361, The second pressure sensor 152 and the second temperature sensor 162 are disposed in the second low pressure gas refrigerant path 113j: and detect respectively the pressure and the temperature of the refrigerant in the second low pressure gas refrigerant path 110 j, The rotation speed sensor 170 is disposed in the engine 60, PC1TYA091 (PQlQ8'56WOOl) - 15/54 and detects the rotational speed ofthe engine 60, [004:6]

The circulating liquid circuit 200 includes an influent circulating liquid temperature sensor 231 and an effluent eirculating liquid 5 temperature sensor 232.

[0047]

Specifically, the influent circulating liquid temperature sensor 231 is disposed in the inlet branch pipe: 211:, and detects the temperature of the circulating: liquid that: flows into the: refrigerantmircuiating liquid 10 heat: exchanger SO (more specifically, the circulating liquid in the inlet branch pipe :21:1). The effluent circulating" liquid temperature: sensor 232 is disposed in the outlet branch pipe 221, and detects the temperature of the circulating liquid that flows out of the refrigerant-circulating liquid heat exchanger 50 (more specifically, the eirculating 15 liquid in the outlet branch pipe 22l).

[0048]

The control device 140 controls, according to detection signals from various sensors, driving of the refrigerant circuit 110, the coolant path 120 and the circulating liquid circuit 200, Thus, the chiller TOO 20 can adjust the temperature of the eirculating liquid that flows in the circulating liquid circuit 200.

[0049]

Specifically, the control device 140 causes the compressor 10 to compress the refrigerant that is suefced from the first low pressure gas 25 refrigerant path 113b and to discharge the compressed refrigerant to the high pressure gas refrigerant path 118 a. When the cooling operation to cool the circulating liquid in the circulating liquid circuit 200 is performed, the control device 140 mahes: the four-way valve 111 a first connection state in which the high pressure gas refrigerant path 113a is 30 communicated with the first gas refrigerant path 113c and furthermore M?A091 (PO1O850W001,) - 16/54 the second gas refrigerant path 113¾ is communicated with the first low pressure gas refrigerant path 118 b, Also, when the heating operation to heat the circulating liquid in the circulating liquid circuit 200 Ί& performed, the control device 140 makes the four-way valve 111 a second connection state in which the high pressure gas refrigerant path 113a is communicated with the second gas refrigerant path 113h and furthermore the first gas refrigerant: path 113c is communicated with the first low pressure gas refrigerant path 113b.

[0050]

The refrigerant-ait heat exchanger 20 serves as a condenser to cause the refrigerant to release heat and liquefy· during pooling operation, and serves as an evaporator to cause the refrigerant to absorb heat and vaporize during heating operation. The refrigerant'circulating liquid beat exchanger 50 serves as a cooler to cause the refrigerant to absorb heat and cool the: eixmuI&Cixig liquid during cooling operation, and serves as a heater to cause the refrigerant to release heat and heat the circulating liquid during heating operation. The engine exhaust heat recovery unit 70 serves as an evaporator to cause the refrigerant to absorb heat and vaporize.

[0051]

The first expansion valve 41 and the second expansion valve 42 are: arranged, in parallel, downstream of the bridge circuit 112. In response to the instruction signal from the control device 140, the first expansion valve 41 adjusts the flow rat© of the refrigerant that flows toward the reirigerant-circulating liquid heat exchanger 50 via the bridge circuit 112 during pooling operation, and adjusts the flow rate of the refrigerant that flows toward the refrigerant-air heat; exchanger 20 via the; bridge circuit 112 during heating operation. The second expansion valve 42 adjusts,: in response to the instruction signal from the control device 140, the flow rate of the refrigerant that Sows toward the PCTYA091 (P010856WO01) - 17/54 engine exhaust heat recovery unit 70.

[0052]

The control device 140 includes a processor 141 constituted of a microcomputer such as a GPU (central processing tthit), and a memory 142: including a non-volatile memory such as: a BUM (read only memory! and a volatile memory such as a BAM (random access memory).

EU06.0I

In the control device 14¾ the processor 141 executes a control program previously stored in the ROM cf the· memory 142: by loading the control program on the BAM. of the memory 142, Thus, operations: of the respective component elements: are controlled, [00:54]

With the chiller 100 a:s described above, it is possible to adjust the temperature of the circulating liquid: that flows in the: circulating liquid circuit 200: by performing appropriately the cooling operation or the heating operation, [0055]

First, the cooling operation performed by the chiller 100 will be described with reference to PIG. 3. the heating operation performed bv the chiller 100 will be described with reference to FIG. 4, [0056] [Uooling Operation] PIG. 3 is a schematic block diagram showing the chiller 100 that: performs the cooling operation.

[0057]

When the chiller 100 performs the cooling operation, the control device 140 switches the four-way valve 'ill to the first connection state in which the high pressure gas refrigerant path 113a is, communicated with the first gas refrigerant path. I13e and finrthermore the second gas refrigerant path. H3h is communicated with: the first low pressure gas PCTYA091 (PO1O856WO01) - 18/54 refeigerant path 113b. In this way; the refrigerant in a state of high pressure gas (hereinafter referred to as the “high pressure gas refrigerant”) that is discharged from the .compressor 10 flows into the refrigerant'air heat exchanger 20 via the oil separator 81« [0058]

The temperature of the high pressure gas refrigerant that flows into the refrigeranhair heat exchanger 20 is higher than the temperature of the air that passes through the refrigerant-air heat exchanger 20. For this reason, the heat is transferred from the high pressure gas refrigerant to the air. As a result, the high pressure gas refrigerant loses the condensation heat and liquefies, thus becomes the refrigerant in a state of a high pressure liquid (hereinafter referred to as the -high pressure liquid refrigerant”). That is, in the cooling operation, the refrigerant’air heat exchanger 20 servos as a condenser of the refrigerant, in which the high pressure gas refrigerant releases heat.

[0059]

The high pressure liquid reftagerant flows from, the re frige rant-air heat; exchanger 20 to the first intermediate connection point PI of the bridge circuit 112 via the first refrigerant path 113d. Since the first intermediate connection point Pi is located on the outlet side of the: second check valve 112h and oh the inlet side of the first cheek valve 112a, the high pressure liquid refrigerant does not flow to the; second cheek valve 112 b and the third check valve 112c, but flews: to the high pressure liquid refrigerant path 113e from the first intermediate connection point Pi, via the first check valve 112a and the outlet connection point P2.

[0060]

When the; control device 140 performs the cooling operation, it opens the first expansion valve 41 and closes the second; expansion valve 42, so that the high pressure liquid refrigerant flows through, the first PCTYA09.1 (P010838W001) - 19©4 expansion, valves; 4# hmj? does not flow through the second expansion valve 42. Thus-,, tlie high pressure liquid refrigerant passes through the first expansion, valve 41 via the receiver S3 disposed in the high pressure liquid refrigerant path 113e. 5 [0061]

When passing through the first expansion valve 41, the high pressure liquid refrigerant expands and becomes a refrigerant in a: state of a low pressure gas-liquid, two phase (hereinafter referred to as the “low pressure gas-liquid two phase refrigerant”). The low pressure gas-10 liquid two: phase refrigerant flows from the first low pressure gas-liquid two phase refrigerant path 113f to the: inlet connection point F4: of the bridge circuit 112, The inlet connection point P4 is located on the inlet side of the second check valve 112b and the fourth check valve 112d. However, as described above, the high pressure liquid refrigerant flows IS through the first intermediate connection point PI and the outlet connection point P2. For this reason, the low pressure gas-liquid two phase refrigerant does mot flow to the second check valve 112b and the third check valve 112c because of the pressure difference front the high pressure liquid refrigerant that flows through the first intermediate 20 connection point PI and the outlet connection point P2. The low pressure gas-liquid two phase refrigerant flows from the inlet connection point P4 to the refeigefantieifcnlafcmg liquid heat exchanger 50' via the fourth cheek valve lj;2d, the second intermediate connection point P3 and the second refrigerant path 118g. 2S: [0062]

The temperature of the: low pressure gas-liquid two phase refrigerant that flows on the side of the refrigerant circuit TIG relative to the refrigerant-circulating liquid heat exchanger 50 is lower than the temperature of the circulating liquid that flows on the side of the 30 circulating liquid circuit: 200 relative to the refrigerant-circulating liquid PGTYA091 (Ρ01086'βΜ3θΰ - 20/54 heat exchanger 50. For this reason, the heat is transferred from the circulating liquid to the low pressure gas-liquid two phase refrigerant. As a result, the low pressure gas-liquid two phase refrigerant obtains; the evaporation heat and vaporizes, thus becomes the refrigerant in a state 5 of a low pressure gas (hereinafter referred to as the “low pressure: gas; refrigerant”),: Qn the other hand, the circulating liquid is cooled by the:1 heat absorbing action of the refrigerant. That is, in the cooling operation, the re&igerant"circulating liquid1 heat exchanger 50 serves as; a cooler of the circulating liquid, in which the low pressure gas-liquid 10 two phase refrigerant absorbs heat.

[0063]

After that, the low pressure gas reMgerant flows from the refrigerant-circulating liquid: heat exchanger 50 to the: second gas refrigerant path 113h. At this time, the control device 140 15 communicates the second gas refrigerant path 118h with the first low pressure gas refrigerant path 113b % the lour-way Valve 111. Thus, the low pressure gas refrigerant is sucfed into the compressor 10 via the accumulator 82 disposed in the first low pressure gas refrigerant path 113b.

In the chiller 100, the above- described series of operations as the cooling operation are repeatedly performed.

[0065] [Heating Operation] 25 FIG. 4 is a schematic block diagram showing the chiller 100 that performs, the heating operation.

[00861:

When the chiller 100 performs the heating operation, the control device 140 switches: the four-way valve 111 to the second connection state 30 in which the high pressure gas refrigerant path 113a is communicated: OOl)- 21/54 PCTYMm (P0lQ856Wi with the second gas re&igerant path I13h and furthermore the first gas refrigerant path lido is communicated with the first low pressure gas refrigerant path 113b. In this way, the high pressure gas refrigerant that is discharged from the compressor 10 flows into the refrigerant-circulating liquid heat exchanger 50 via the oil separator 81, [0067]

The temperature of the high pressure gas refrigerant that flows on the side of the refrigerant circuit 110 relative to the refrigerant-circulating liquid heat exchanger SO is higher than the temperature of the circulating liquid that flows on the side of the circulating liquid circuit 200 relative to the reirigerant'eirculating liquid heat exchanger SO, For this reason, the heat is transferred from the high pressure gas refrigerant to the circulating liquids As a result, the high pressure gas refrigerant loses the condensation heat and liquefies, thus becomes the high pressure: liquid refrigerant. On the other hand, the circulating liquid is heated by the heat releasing: action of the refrigerant That is, in the heating operation, the refrigetantwirculatmg liquid heat exchanger 50 serves as a heater of the circulating: liquid, in which the high pressure gas refrigerant releases heat..

[0068]

The high pressure liquid refrigerant flows from the refrigerant-circulating: liquid heat exchanger 50 to the second intermediate Connection point: l53 of the bridge circuit 112 via: the second refrigerant path 113g. Since: the second: intermediate connection point F3 is located on the inlet side of the: third check valve H2c and on the: outlet side of the fourth check valve 112d, the high pressure liquid refrigerant does not flow -to the first check valve 112a and the fourth check: valve: 112b, hut flows: to the high pressure: liquid refrigerant path 113e from the, second intermediate connection point P8. via the third check valve 112c and the outlet connection, point P2. PQTM:Q:9X (PG10858WOQ1) - 22/54

Wliea the control device 140 performs the heating operation, it opens the .frrst ·expansion."yelve 41 and close® the second expansion valve 42,: so that the high pressure liquid refrigerant flows through, the first expansion valve 41 but does not flow through the second expansion valve 42:,: Thus, the high pressure liquid refrigerant passes through the first expansion valve 41 via the receiver 83 disposed in the high pressure liquid refrigerant path 113e.

[00 70]

When passing through the first expansion valve 41, the high pressure liquid refrigerant expands and becomes the low pressure gas' •liquid, two phase refrigerant. The low pressure gasdiqaid two phase refrigerant flows from the first low pressure g&sTiqnid two phase refrigerant path I13f to the inlet connection point F4 of the bridge circuit 112; The inlet connection point P4 is located on the inlet side of the second cheek valve 112b and the fourth check valve 112d. However, as described above, the high pressure liquid refrigerant flows through the second intermediate connection point P3 and the outlet connection point P2. For this reason, the low pressure gas-liquid two phase refrigerant does not flow to the fourth check valve 112d and the first check valve 112a because of the pressure difference from the high pressure liquid refrigerant that flows through the second intermediate connection point 'P-3 and the outlet connection point P2. The low pressure gas-liquid two phase refrigerant flows from the inlet connection point P4 to the refrigeranfrair -heat exchanger 20 via the second check valve 112b and the first refrigerant path 113d.

[00711

The temperature of the low pressure gas-liquid two phase refrigerant that flows through the refrigerant'air heat exchanger 20 is lower than the temperature of the air that passes through the PCTYA091 (Pill0856WO 01.) - 23fo4 refrigerant-air hoafc exchanger 20. For this reason, the heat is transferred from the air to the low pressure gasdiqnid two phase refrigerant. As a result, the: lew pressure gasdiquid two phase refrigerant obtains the evaporation heat and vaporizes:, thus becomes the law pressure gas refrigerant, 'That is, in the heating operation, the refrigerant"air heat exchanger 20 serves as an evaporator of the refrigerant, in which the low pressure gas-liquid two phase refrigerant absorbs heat.

After that, the low pressure gas refrigerant flows from the refrigerant-air heat exchanger 20 to the: first gas refrigerant path 113c. At this time, the control device 140 communicates the first gas refrigerant path 113c with the first low pressure gas refrigerant path 118b by the fbur-way valve 111. Thus, the low pressure gas refrigerant is suc’fced into the compressor ID via the accumulator: 82 disposed in the first low pressure gas refrigerant path 113b.

[0073] in e chiller 100, the above'described series of operations as the heating operation are repeatedly performed.

[Defrost1 Operation]

Dhiing·ihe-atiHf' Operation,, the low pressure gas-liquid two phase refrigerant is supplied to the refrigerant-air heat exchanger 20. thus piping in the refrigerant-air heat exchanger 20 is cooled. In this case, frost may: adheres to: the piping in the refidgerahfoair heat exchanger 20 depending on conditions such as an outside air temperature. Then, the chiller 10:0 performs the defrost operation.

Next, the defrost Operation performed by the chiller 100: will be described with reference to FIG. 5. PCT5TA091 (P010856W001) - 24/54- [0076] FIG, 5 is a schematic block diagram showing the chiller lOO that performs the defrost operation.

[0077] 6 When the: chiller 100 performs the defrost operation, the control device 140 switches, as in the cooling operation, the four-way valve 111: to the first connection state in which the high pressure gas refrigerant path 118a is communicated with the first gas refrigerant path 113c and furthermore the second gas reMgerant path 113h is communicated with 10 the first low pressure gas refrigerant path 113b. In this way, the high pressure gas refrigerant that is discharged from the compressor 10 flows into the re frige rant “air heat exchanger SO via the nil separator 81.

[0078]

The high pressure gas refrigerant that flows through the 15 refrigerant-air heat exchanger 20 loses, as in the cooling operation, the condensation heat and liquefies, thus; becomes the high pressure liquid refrigerant. That is, in the: defrost operation, the refrigerant-air heat exchanger 20: serves as a condenser of the refrigerant, la which the: high pressure gas refrigerant releases heat, 2G [0079]

Similarly to the cooling operation, the high pressure liquid refrigerant flows from, the refrigerant-air heat exchanger 20 to the high pressure liquid refrigerant path 1Ί 8e via the first refrigerant path 113d, and the first intermediate connection point PI, the first check valve 112a 25 and the o utlet connection point P2 of the bridge circuit 112.

[0080]

CO

When the control device 140 performs the defrost operation, it. opens the second expansion valve 42 and closes the first expansion valve 41, so that the high pressure liquid refrigerant fiows through the second Q expansion valve 42 but does not flow through the first expansion valve 41. PCTYA091 (P0108S6W001) - 25/54

Thus, the high pressure liquid refrigerant passes through the second expansion, valve 42 via the receiver 83 disposed in the high pressure liquid refrigerant1 path '113e.

[0081] 5 When passing through the second expansion valve 42, the high pressure liquid refrigerant expands and becomes the low pressure gas-liquid. two phase refrigerant, The low pressure gas-liquid, two phase refrigerant flows from the second low pressure gas-liquid two phase refrigerant path 113'i to the engine exhaust heat recovery unit 70. 10 [0082]

The tempop&txire of the low pressure: gas-liquid two phase refrigerant: that flows on the side of the refrigerant circuit 110 relative to the engine exhaust heat recovery unit 70 is lower than the temperature of the engine Coolant that Sows on the side of the coolant path 120 15 relative to the engine exhaust heat recovery unit 70. For this .reason., the heat is: transferred from the engine coolant to the low pressure gas-liquid two phase;: refrigerant,: As a result, the low pressure gas-liquid, two: phase refrigerant obtains: the evaporation heat and vaporizes, thus becomes the low pressure gas refrigerant. That is, in the: defrost 20: operation, the engine exhaust heat recovery unit 70 serves as an evaporator of the refrigerant, in which the: low pressure gasdiquid two phase refrigerant absorbs heat, [0083]

After that, the low pressure gas refrigerant flows from the engine 25 exhaust heat recovery unit 70, and is sucked, into the compressor 10 via the second low pressure gas refrigerant path 113], the confluence: point P5 of the first low pressure gas refrigerant: path 113b, the coufrueuce path 113b 1* and the: acourmilator 82.

[0084] 0-3

In the chiller 100,.. the above-described series of operations as, the EGTm091 CEO10856WO01) - 26/5-1 defrost operation are repeatedly performed.

In tire defrost operation, the high pressure gas refrigerant is supplied to the refrigerant'air heat exchanger 20, thus, the piping in the 5 refrigerant-air heat exchanger 20 is heated. As a result, frost that adheres to the refrigerant-air heat exchanger 20 is removed by the heating operation. Furthermore, in the defrost operation, since the low pressure gas-liquid two phase refrigerant does mot flow to the refrigerant-circulating liquid heat exchanger SO, the decrease in the 10 temperature of the chrqulafing liquid according to evaporation of the refrigerant does not occur.

[0088] [Control on Each Chiller in. Chiller System]

In the -chiller system I in which a plurality of chillers IQf) (1¾ to 15 100 (n) is connected to each other, generally, the number of chillers to be operated is mcreased/deereased, out of the plurality of chillers 100 (l) to 100 (n), according to a required load capacity In this case, it is desired to level respective cumulative operation times of the chillers 100 (!) to 100 (n) by not operating particular chillers unevenly but operating each 20 Chiller 100 (1¾ tq 100 (n) evenly, from the viewpoint that it is preferable to perform maintenance on the plurality of chillers 100 (l) to 100 (n) at the same time. Here, the “operation” means the “cooling operation” or the “heating operation”, which does not include the “defrost operation”. 10087] 25 In. this regard, iii the conventional chiller system as described above, when the load capacity is increased, a newly active chiller is added after the operation capacity of each of the current active chillers reaches 100¾ output (rated output) (see the Patent Document 1). Thus, when a partial load at which the operation output does not reach the SG rated output is continuously applied, no newly active chiller is added FCTYA091 (P010856WOf) 1) - 27/54 while such; a partial load is being continuously .applied. As a result, the respective cumulative operation times of the chillers are likely to vary largely. 5 In consideration of the above circumstances* the chiller system 1 according to this embodiment includes a Control mechanism to control the operation of each chiller 100 (l) to 10G (n) as described below, [0089]

That is, in this embodiment, the control mechanism is an 10 aggregate of; the respective control devices 140 of the chillers 100 (l) to 100 (n). The control devices 140 (l) to 140 |n) are connected to each other in order to communicate with each other. In the chiller system 1, one chiller Is designated as a master chiller (i) (i is an integer of from 1 to n) out of the plurality of chillers 1Q0 (l) to 100 In). Mote that the IS control mechanism may be a control device that integrally controls the chillers 100 (1) to 100 (n) and that is provided separated from the chillers 100 (l) to 100 (n).

[0090]

When one or more chillers 100 are operated out of the plurality of 20 chillers 100 (l) tp 100 (n) (servant chillers, and the master chiller 100 ¢1)), the master chiller 100 (ί) (specifically the control device 140 (i)) transmits an operation command to one of the stopped (inactive) chillers 100 if a relation Qf ί (N+l) > is satisfied, where Qi represents a [total required operation capacity]; that is a total operation capacity required of 25 thetatlleaet; one: active chiller 100, H represents a [number of currently active chillers] that is the number of the active chillers 1.(10, and Qp represents a [partial load capacity] that is the load capacity of a predetermined: partial load. Here, the; [partial load capacity] Qp can be set to a value (fp* example, 4kW) that is obtained by multiplying the 30 rated output (for example, lOkW) of the: chiller 100 by a predetermined PGTTA091 (P010856WGQ1) ‘ :28/¾ partial load capacity ratio (i,©v:J lead capacity ratio greater than 0 and smaller than 1, for example, 40%). If the chiller 10.0" that receives the operation command is the master chiller 100 (i) itself, the master chiller 100 (i) transmits the operation command to itself.

[0091] in other words, the master chiller 100 (i) maintains the [number of currently active chillers] N (for example, two chillers) when the [total required operation capacity] Qt is less than a [reference load;capacity for increasing active chillers] Qi (for example, 12&'W) obtained by multiplying: the number of the operated chillers (N + 1) (for example, three chilfers), which is obtained by adding one chiller to the. [number of currently active chillers] N (for example, two chillers), by the [partial load capacity] Qp (for example, 4kW). In contrast, the master chiller 100 (i) increases the number of the active chillers 109 by one (for example, increases the number of the active chillers to·: three) when: the (total required operation capacity] Qt is not less than the [reference load capacity for increasing active chillers] Qi (for example, I2kWl.

[0092]

Here, the stopped chiller 100 means naturally the chiller that is; not being operated currently but is capable of being operated. A chiller on standby can be exemplified.

[0093]

When the stopped chiller 100 (specifically; the control device 140 of the stopped chiller 100) receives the operation command from the master chiller 100 (i), the operation of the stopped chiller 100 is started.

[0094] :

Also, when one or more: chillers 1QQ are operated out of the plurality of chillers 100 (11 to 100 :(n) including the master phfifer 100 (i), the master chiller 100 ;{i) (specifically, the control device 140 (i)) transmits a stop command to One of the active chillers 100 if a relation POTA09I (P010856W001) - 29/54

Qt / N < Qp is satisfied. in this way, it is possible to set a lower limit of the operation capaeity per active chiller 100 when the load capacity decreases. If the chiller 100 that receives the stop command is the master chiller 100: (i) itself, the master chiller 100 (i) transmits the stop 5 command to itself.

[0095]

In other words, the master chiller 100 (i) maintains the [number of currently active chillers] N (for example, three chillers) when the [total required operation capacity] Qt is greater than a [reference load 10 capacity for decreasing active chillers] Qd (for example, 12kW) obtained by multiplying the [number of currently active chillers] M (for example, three chillers) by the [partial load capacity] Qp (for example, 4kW), i.e,;j when an [operation capacity per chiller] is greater than the [partial load capacity] Qp (for example, 4kW). In contrast, the master chiller 100 (i) IS reduces the number of the active chillers 100 by one (for example, reduces the number of the active chillers to two) when the [total required operation capaeity] Qt is not more than the [reference load capaeity for decreasing active chillers] Qd (for example, 12k W), i.e., 'When the [operation.· capacity per chiller] is not more than the [partial load 20 capaeity] Qp (for example, 4kW).

[0096]

When the active chiller 100 (specifically^ the control device 140 of the active chiller 100) receives the stop command from the master chiller 100 (i), the active chiller 100 is: stopped. 25 [0097] FIGS·. 6 is a graph indicating the control operation performed by the master chiller 100 (i) on each chiller 100 (1) to 100 (8) in the chiller system 1 in which the number n of the chillers 100 is set to eight.

[0098] 30 In ΪΙ& ..6, the [operation capacity ratio per chiller] (3¾] as the PCKhOhl (P01QB56WD01) - 30/54 vertical axis represents the ratio of the operation capacity per chiller 100, That is, when the rated output is 10 [kWl, 40 [%] [operation capacity ratio per chiller] means the operation capacity of 4. [kW].

[Q099]

Also, in FIG, 6, the [total required operation capacity ratio] [%]: as the horizontal axis represents; the: ratio of the [total required operation capacity] Qt that is the sum of each operation capacity (output) of the corresponding active chiller 100* In the ease: where two chillers TOD are operated and the rated output of each chiller 100, 100 is TO [kW], when the [required .operation capacity ratio] of the two chillers 100, 100 is each, for example, 40 [%], the [total required operation capacity ratio], which is obtained by summing up each [required operation capacity ratio] of the two chillers 100, 100 is 80 [%], and the [total required operation capacity] Qt, which is obtained by summing up each [required operation capacity] of the two chillers 100, 100 is 8 [kW], Similarly to the above, in the case where the rated output of the chiller .10.0· is 10 [kW], when the [predetermined partial load capacity ratio], the [reference load capacity ratio for iucreasihg active chillers] and the [reference load capacity ratio for decreasing active chillers] of the chiller 100 are respectively for example, 40 [%], T|0 [%] and 120 [%], the [partial load capacity] Qp, the [reference load capacity for increasing active chillers] Qi and the [reference load capacity for decreasing active chillers] Qd of the chiller 100 are respectively 4 [kW], 12 [kW] and 12 [kW]. As the [predetermined partial load capacity ratio] increases, particular chillers: 100 are likely to be operated unevenly, and as the [predetermined partial load cape.city ratio! decreases, the operation efficiency is likely to degrade. Therefore, it is preferable to set the [predetermined partial load capacity ratio] to. for example, 40 [%], keeping a good balance between the above two cases.

[0100] PCTYA091 (POlOSSeWOQl) - 31/54

Next, in the control operation on- each chiller 100 (l) to 100 (8), the cases where: the ..[total required operation capacity] Qt increases so that the number of the chillers 100 is increased and where the [total required operation capacity] Qt decreases so that the number of the chillers 100 is decreased will he described helow with reference to FIG. 6, In the example indicated, in FIG, 6, the [predetermined partial load capacity ratio] is 40%, [0101] ©ase in Which Number of Chillers Is Increased)

In the case where the number of the chillers 10O; is increased, when the number of the active chillers IQG is one (see al in FIG, 6) and when the [total required operation capacity ratio] is less than the [reference load capacity ratio for increasing active chillers] (80 [%]) that is obtained by multiplying the number of the chillers (two), which is obtained by adding one chiller to the [number of currently active chillers] (one), by the [predetermined partial load capacity ratio] (40 [%!), the [number of currently active chillers] (one) is maintained. In this case, the [operation capacity ratio] per chiller is in the range of more than 0 [%] to less than 80 [%] (- 80 [%ί / One chiller). On the; other hand, when the [total required operation capacity ratio] is not less than the [reference load capacity ratio for increasing active chillers]: (80 [%]), the number of the active chillers is increased by one, thus becomes: two.

[0102]

Also, when the number of the active chillers: 100 are two (see. a2 in FIG. 6) and when the [total required operation capacity ratio] is less than the [reference load capacity ratio for increasing active: chillers] (120 [%]) that Is obtained by multiplying the number of the: chillers: (three), which is obtained by adding one chiller to the [number of currently active chillers]; (two), by the [predetermined partial load capacity ratio] (40 [.%]), the [number of currently active chiliersj (two) is maintained. In this PCTYA091 (FOlOSbbWOOl) * 32/54 case, the [operation capacity ratio] per chiller is in the range of not less than 40 [%] (= 80% ./ 2 chillers] to less than 60 {%] (= 120 [%) / two chillers). On the other hand, when the [total required: operation capacity ratio] is not less than the [reference load capacity ratio for increasing active chillers] (120 [%]). the number of the active chillers is increased by one, thus becomes three.

[0103]

Also, when the number of the active chillers: 100 are three (see a3 in BIG. 6) and when the [total required operation capacity ratio] is less than the [reference load capacity ratio for increasing active chillers] (160 [%]) that is obtained by multiplying the number of the chillers (four),: w hich is obtained by adding one chiller to the [number of currently active chiller] (three), by the [predetermined partial load capacity ratio] (40' [%}), the [numher of currently active chillers] (three) is maintained. In this case, the [operation capacity ratio] per chiller is in the range of not less than 40 [%] ¢= 120 [%] /three chillers) to less than 53-.:3: [%j (=160 [%J / three chillers). On the other hand, when the [total required operation capacity ratio] is not less than the [reference load capacity ratio for increasing active chillers] (160 [%]), the number of the active chillers: is increased by one, thus becomes four.

[0104]

Similarly to the above, the number of the active chillers :1.00 m increased. When the number of the active -chillers 100 is eight, (the maximum), the [operation capacity ratio] per chiller is in the range of mot less than 40 [%] (= 320 [%] / eight chillers) to not more than 100 [%] (= 800: [%] / eight chillers).

[01053 (Case in Which Number of Chillers is Decreased)

In the case where the number of the chillers 100 is decreased, when the number of the active chillers 100 is eight (see 01 in FIG. 6) and. PCTYA091 (PO'I 0856WOOl) - 33/54 when the [total: requited operation capacity ratio]: is more than the [reference load capacity ratio fox. decreasing active chillers] (320 [%]). that is obtained by multiplying the [number of currently active chillers] (eight) by the Epredetermined partial load capacity ratio] (40 [%]), the 5 [number of currently active chillers] (eight) in maintained. In this case, thn [operation capacity ratio] per chiller is in the? range of more than 40 [%.l (=320 l%\ / eight chillers) and not more than 100 [%1 (SOQ [·%] / eight chillers). On the other hands, when the [total required operation capacity ratio] is not more than the [reference load capacity ratio for 10 decreasing active eh biers] (320 [%]), the number of the: active chillers is •decreased by one, thus becomes seven.

[0106] ί-ο

Also, when the number of the active chillers 100 is seven (see B2 in F10. 6) and when the [total required operation capacity ratio] is more 15 than the [reference load capacity ratio for decreasing active chillers] (280 [%]) that is obtained: by multiplying the [number of currently active chillers] (seven) by the [predetermined partial load capacity ratio] (40' [%]), the [number of currently active chillers] (seven) is maintained. In this case, the [operation capacity ratio] per chiller is in the range of more £0 than 40 [%] (=280 [%] / seven chillers) to not more than 45.7 :[%] (=320 [%] / seven chillers). On the other hand, when the [total required operation capacity ratio] is not more than the [reference load capacity ratio for deereasing active chillers] (28Q: [%]).,: the number of the active chillers is decreased by one, thus becomes: six. δ [0107]

Also, when the number of the active chillers 100 is six (see 63 in FIG·. 8) and When the [total required operation capacity ratio] is more than the Ireference load capacity ratio for decreasing active chillers] (240 [Μ]) that: is obtained by multiplying the [number of currently active 30 chillers] (six) by the [predetermined partial load capacity ratio] (40 [%]}, PCm.091 (ΡΘ1Q8S6WO 01) - :34/54 the; [hUmbar of currently active. chillers} (six) is .maintained. In this case, the [operation capacity patio] per chiller is. in the range of more than 40 E%] 0=240 [%] / six chillers/ to not more than 46.6 [%] N2S0 [%] l six chillers). On the other hand, when the [total required operation 5 capacity ratio] is not more than the [reference load capacity ratio for decreasing active chillers] (240 [%)), the number of the active chillers is decreased by one, thus becomes five.

[0108]

Similarly to the above, the number of the active chillers 100 is 10 decreased. When the number of the active chillers 100 is one (the minimum), the [operation capacity ratio] per chiller is in the range of more than 0 [34] to net more than 80 [%] (~ 80 [%] / one chiller).

[0109]

In the example indicated in. FIG. 6, the number of the chillers 100 15 is set to eight. However, the number of the chillers 100 is not limited thereto. The number of the chillers 100 may be in the range of two to seven or may be nine or more.

[0110:1 (Operation by Master Chiller to Control Each Chiller) 20 FIG. 7 is a flowchart indicating steps of one example of the control operation by the master chiller (i) on each chiller 100 (l) to 100 (a); so as to control the number of active chillers.

[0111]

In the control operation indicated in FIG. 7, first, the control gs device 140 of the master chiller (i) sums Up each output of the corresponding chiller 100 Cl) to 100 (n) so as to calculate the total required operation capacity (current load capacity) (step SI).

[0112]

Next, the control device 140 of the master chiller (i) compares the 30 calculated total required, operation capacity with the previous total PGTYhQDl (PQ1G806WO01) - 33/54 required operation capacity :(defhnlt: 0) stored in the memory 142 so as to determine: whether the former is larger than the latter (step S2h When the control device 140 determines that the calculated total required operation capacity is larger than the previous total required operation 5 capacity (step S2: Yes), then the control device 140 determines; whether the number: of the active chillers 100 is maximum or not (step S3)* When the control device 140 determines that the number of the active chillers 100 ia maximum (step S3; Yes), the procedure advances to step; SO, When the control device 140 determines that the number of the 10 active: chillers: 100 is: not maximum (step S3; No), then the control device 140 determines whether the relation Qt / (N+l) '> Qp is satisfied or not (step S4)> Ι0Π3Ϊ

When the control device 140 of the master chiller (i) determines 1:6 that the relation Qt / (N+l) > Qp is not: satisfied in step S4 (step S4^ No), the procedure advances to step S9, When the control device 140 determines that the relation Qt / (N+l) > Qp is satisfied (step S4- Yes), the control device 140 increases the number of the active chillers 100 by one (step SS),: thus the procedure advances to step S9. 20 [0114]

Meanwhile, when the control device 140 of the master chiller (i) determines that the total required operation capacity is equal to or smaller than the previous total required operation capacity in step S2 (step No), then the: control device 140 determines whether the 25 number of the active chillers 100 is minimum or not (step SO), When the control device 140 determines that the number of the active chillers 100 is minimum (step S6: Yes), the procedure advances to step 89. When the control device 140 determines that the number of the active chillers 100 is not minimum (step .S6- No), then the control device 140 30 determines whether the relation Qt / N < Qp is satisfied or not (step S7)«

PCTY.A091 CP010856W001) - 36/M icrnsl

When, the control device: 140 of the master chiller (i) determines that the relation Qt / N < %p is not satisfied in step·· $7 (step &T· No)* the procedure advances to step S9. When the control device 14:0 determines B that the relation Qi /'Ν' <Qp is satisfied (step S7b'Yes),.. then the control device 140 reduces the number of the active chillers 100 by one (step S8)> thus the: procedure advances to step S9.

[0116]

The control device 140 of the master chiller :|i) subsequently 1Θ stores the total required operation capacity in the memory 142, and continues the procedure of step Si to step Sip until it receives the termination instruction (step S'lOl No). When it receives the termination instruction (stop SlQ: Yes), the procedure: is terminated, [0117] 15 Selection of Chiller When Increasing/Beereasing Number of Active

Chillers)

In this embodiment, the plurality of chillers 100 (I) to 100 (xi) including- the master chiller 100 (i) can be in any of the fallowing states: a “normal state”; an “alarming state” in which, an alarm is being 20 transmitted; and a “before-alarming state” that is before transmission of the alarm (specifically, a state in which a forecast is transmitted before the transmission of the alarm) between the “normal state” and the “alarming state”.

[0118] 25 Specifically, each of the chillers. 100 (l) to 100 (η) transmits an alarm when it becomes in. an inoperable state in which the operation cannot be continued, while ft transmits a forecast to get attention of a user when it Becomes: in qUasi'operation state in which the operation is being continued although it cannot be deemed as a normal state. Here, 30 examples of the: "inoperable state” can include: a physically inoperable TPTYA.091 (3?010856WO01) - 37/54 state due to a significant abnormality such as an engine failure; a state that .requires inhibition of the operation although the operation is physically possible;: and· a state in which the operation is switched to the defrost operation. Also, examples of the “quasiOperation state” can include, a state in which the inhibition of the operation is: not needed although a minor -abnormality such -as a temporary abnormality (for example, a temporarily abnormal output from the sensors and. the like) occurs ’When the master chiller 100! (i) (specifically, the control device 140 Ci)) transmits the operation command to one chiller 100 of the stopped chillers 100 out of the plurality of chillers 100 (1) to 100 in.) including the master chiller 100 (i), the master chiller 100 (i) selects the chiller 100 as a target for a next operation command in the order of: the active chiller 100 in the “beforemlarmiiig state”; the stopped chiller 100 in the “before-alarming state”; the active chiller 100 in the “normal state”; and the stopped chiller 100 in the “normal state”. (since the •master chiller 100 (i) actually transmits the operation command to the stopped chiller 100. it selects the target chiller 100 for the next operation command substantially in the order of the stopped chiller in the “beforg-alarming state” and the stopped chiller 100 in the “normal state”.

[0120]

Furthermore, when the master chiller 100 (i) transmits the operation command to one chiller 100 of the stopped chillers 100 out of the plurality of chillers 100 .(1) to 100: (n) including the master chiller 100 li), the master chiller 100 (i) selects·,, if the chillers 100 are in the samn state (i.e., have the same priority);, the target chiller .1.00: for the next: operation command in ascending order of a cumulative output amount (kWh) obtained by summing the outputs (kWh) from an initial state (a state in which no predetermined maintenance has been performed yet) or PCTYAdSl (ΡΘ10856W00,1)- - 3M>4 fkem the time point at which the pie determined maintenance has been performed (i,e,5 the time: paint at which the; latest maintenance has been performed). to 1211

When the master chiller 100 (i) (specifically; the control device 140 (i)) transmits the stop command to one chiller 100' of the active chillers 100, the master chiller IQD (f) selects the chiller 100 as: a. target for a next stop command in the order of the stopped chiller 100 in the “normal State"; the: active chiller 100 in the "normal state"; the stopped chiller 100 in the %e:fcre‘alarming state"; and the active chiller 100 in the “before-alarming: state”. Since the piaster chiller 100 (i) actually transmits the stop command to the active chiller 100, it selects the target chiller 100 for the next stop command substantially in the order of the active chiller 100 in the ‘'normal state" and the active chiller 100 in the % e fore - alarm! ng State”, [0122]

Furthermore, when the master chiller 100 ίί) transmits the stop command to one chiller 100: of the active chillers 100 out of the plurality of chillers 100 (l) to 100 in) including the master chiller 100 (i), the master chiller 100 Ci) selects, if the chillers 100 are in the same state (Le., have the same priority!, the target chiller 100 for the next stop command in descending order of the cumulative output amount (kWh) obtained by summing the outputs (kWh) from an initial state (a state in which no predetermined maintenance has been performed yet) or from the time point at which the predetermined maintenance has Been performed (i.e., the time point at which the latest maintenance has been performed). [0123] FIB. 8 is a table for determining the priority of the chillers 100 when inereasing/deereasing the number of the active chillers 100. In. FIG, “Ba” represents the active chiller 100 in the "before-alarming PCT5&091 (PO1O806WPO1) - :30)64 state”, “Bs” represents the .stopped chiller 10Q in the ''‘before-alarming state”, “Na” represents the active chiller 100 in the “-normal state:”, “Ns” represents the stopped, chiller 100: in the “normal state”, and “X* represents the chiller 100 in the “inoperable state”. 5: [0124]:

When inereasing/deereasing the number of the active chillers: 100, the chiller can be selected by step l.lj to step .til] as shown in FIG, 8. Note that in the example in FIG- 8, the case in which, n - 8 is presented- [0125] 10 Step [l]; The chillers: 100 (l) to 100: (8) are rearranged in ascending order of the-cumulative output amount of the engine 80 (i.e,r in ascending order from the left side of the table in FIG, 8).

[0126]

Step [2]: The number of the active chillers 100 in the “before-15 alarming state” -(active chiller number before-alarming) is counted. In the example shown in FIG- 8, the number of “Ba” (two) nut of the chillers 1()0 (:1) to 100 (8) is counted and thus counted number (two) of “Ba” is recorded for each chiller 100 (1) to 100 (8).

[0127]

Is3 0 Step [3]t The number of the stopped chillers 100 iii the “before- alarming state-’ (stopped chiller number before-alarming) is counted. In the example shown in FIG- 8} the number of “Bs” (zero) out of the chillers 100 -(1). to 100: (8) is counted and thus counted number (zero) of “Bs” is recorded for each chiller 100 Cl) to 100 (8). 25 [0128]

Step [4]· The number of the active chillers 100 in the “normal state” (normal active chiller number) is counted. In the example shown in FIG. 8, the number of “Na” (three): out of the chillers 100 (1):-to 100 (8) is counted and thus counted: number (three) of “Na” is recorded, for each 30: chiller 100 (1) to 100 (8). PGTmooi (poiQssewooi) - 40/54

Step [5J- The number of the stopped chillers 100 in the “normal state” (normal stopped chiller number) is counted. In the example shown in FIG·. 8, the number of “Ns” (two): out of the chillers 1,0:0 (l) to 100 (8) is counted and thus counted number (two) of “Ns” is recorded for each chiller 100 (1) to 100 :(:8):.

[0130]

Step [6]· From the smallest side in ascending order of the cumulative output amount (see step El]) of the engine 80 (Le.. from the left side of the table in FIG. 8), if any active chiller 100 “Ba” in the “before-alarming state” exists, a before-alarming operation counter Cl (see FIG. 2) that is stored in the: memory 142 is caused to count up. In the example shown in FIG. 8, out of the alignment order from “1” to “8” of the cumulative output amount of the engine 8¾ the before-alarming operation counter Cl for “Ba” is caused to count up by one at the second chiller “2” and at the eighth chiller “8”, which are “Ba” in the table. .[diail

Step: jj]: From the smallest side in ascending order of the cumulative output amount (see step [l]) of the engine 80 (i.e., from the left side of the table in FIG. 8), if any stopped chiller 100 “Bs” in the “before-alarming state” exists*:a before' alarming operation stop: counter 02 :(sbe FIG. 2) that is stored in the memory 142 is caused to count up. In the: example shown in FIG. S. there is no “Be” in the alignment: order from “1” to "8” of the cumulative output: amount of the engine 8Q:, thus the before-alarming stop counter 02 for “Bs” is not caused to count up at any of the alignment order from “l” to: ’B”.

[0132]

Step [8]' From the smallest side in ascending order of the cumulatiye output apaount (see step l.lj) of the engine 80 (i.e., from the: left side Of the table in FIG. 8), if any active chiller 100 “Ma” in the PCTYA091 (POXOBSeWOOl) - 41/34 “normal state” exists, a normal operation counter C3 (see FIG> 2) that is stored in the memory 142 is caused to count tip. In the example shown in FIG. 8:,: out of the alignment order from to “8” of the cumulative output amount of the engine :80, the normal operation counter C3 for 6 “Na?? is caused, to count up "by one: at the first chiller “1”, at the third chiller “S” and at the sixth chiller “6”,- which are “Na5! in the table.

[0133]

Step [9.1- From the smallest side in ascending· order of the .cumulative outp ut amount (see step tli)of the engine 60 (i.e., from the 10 left side of the table in FIG. 8), if any stopped chiller 100 “Us” in the “normal state” exists, a normal operation stop counter C4 foee FIG. 2) that is stored in the memory 142 is caused to count up. In the example shown in FIG·. 8, out of the alignment order from “1” to **£” of the cumulative output amount: of the engine 60, the normal operation stop 15 counter 04 for “Ns” is caused to count up by one at the fourth chiller “4” and at the fifth chiller “5”,: which are “Ns” in the table;.

[0134]

Step [IGF From the smallest side of ascending order of the cumulative output, amount (see step 11]) of the engine 60 (i.e., from the 20 left side of the table in FIG. -8),. if any chiller 100 “X”· in the “inoperable state- exists, an inoperable state counter GO (see FIG» 2) that is stored in the memory 142 is caused to count up. In the example shown in FIG. 8, out of the alignment order from “1” to -‘8” of the cumulative output amount of the engine 60, the inoperable state counter G§ for “X” is 25 caused to count up by one at the seventh chiller “7”, which is “X” in the table, [01351

Step [11]·· In order to determine priority of the chiller to he operated out of the stopped chillers 100 and the; priority of the chiller to So; he: stopped out of the active chillers 100, (Expression 1) to (Expression; 6) PCTYA09! (P010856W001) - 42/54 described below are used feased. bitt Ike values obtained: by steps [.1} to [10], Here, as. each value obtained from (Expression 1) to (Expression 5) becomes: smaller, it represents: a 'higher priority to determine which chiller of the stopped chillers 1Q0 should be operated, while as it becomes greater,; it represents a higher priority to: determine Which chiller of the active chillers 100 should be stopped:.

Active CMiler IQG “Ba” in “Before-Alarming State”

Priority Value of “Ba” ~ Value Counted up by Before-Alarming Operation Counter 01 for “Ba” (Expression if

In the example shown inΕϊΟ, 8, out of the alignment order from '“I” to “8” of the cumulative output amount of the engine 60, the priority value of “B.a” at the second alignment order “2” equals “l” (see the table, the shaded value at the second column “Ba” from the left side and at the: row of step [6]). The priority value of “Ba” at the eighth alignment order “8" equals “2” (see the table, the shaded value at the right most column.: “Ba” and at the row of stop [6]), * Stopped Chiller 100 “Be” in “Before-Alarming State”

Priority Value of “Bs” = Value of [Active Chiller “Ba” Number Before-Alarming] Φ Value Counted. Up by Before-Alarming Operation Stop Counter C2 for “Bs” (Expression ..2)

In the example shown in PICE 8, no priority is determined since there is no chiller “Bs” in the alignment order from “i” to “8” of the cumulative output amount of the engine 80. • Active: Chiller 100 “Na” in “formal State”

Priority Value Of “Na” ~ Value of [Active Chiller “Ba” Number Before·* AlarmingJ 4- Value of [Stopped Chiller “Bs” Number Before Alarming.] + Value Counted Up by Normal Operation Counter 03 for “Na” (Expression 3)

In the example shown in FIC.: 8, out of the alignment order from. “1” to “8” of the cumulative output amount of the engine 60, the priority PCTOMi (P010856WD01} - 43/54 value of “Na” at the first lalighmeni order "l” Is· expressed by the expression “2” + “p” + “1” == “3” (see the table, the total value of the respective shaded values at the left most column.: :‘‘Na?? and at the rows: of steps [2], [3j and [81), The priority value of “Na” at the third alignment order “3” is expressed by the expression “2” + “Q” ·+ “2” » “4” (see the table, the total Value of the respective· shaded values at the third column “Na” :&om the loft and at the: rows of steps [2], 1.8,3 and 1.8]), The priority value of “Na” at the sixth.: alignment order 4<6” is expressed by the expression “2” + “0” + “3” ~ “5” (see the table, the total value of the respective shaded values at the third column “Ha” from the right and at the rows of .steps [2], [3.1 and [81), * Stopped Chiller 100 “Ns:” in “Normal State”

Priority Value of “Ns” - Value of [Active Chiller “Ba” Number Before-Alarming] -t- Value of [Stopped Chiller “Bs” 'Number Before Alarming] +Value of [Normal Active Chiller “NaM Number] + Value Counted Up by Nomnal Operation Stop Counter C4 for “Ns” (Expression 4)

In the example shown in FIG, 8., out of the alignment order from “1” to “8” of the cumulative output amount of the engine 60, the priority value of “Ns* at the fourth alignment order “4” is expressed by the expression “2” + “0” + “3" * “l5i = “& (see: the table, the total value of the respective shaded values at the fourth column “Ns” from the left and at the rows of steps [2-1, [3], [4] and [9]). The priority value of “Ns” at the fifth alignment order “5” is expressed by the expression “2” + "0” + “3” + "2” = “7” (see the table, the total value of the respective shaded values at the fourth column “Ns” from the right and at the rows of stops [2.S, [3], [4] and [9]). • “inoperable State” Chiller 100 “X” priority Value of “X” = Value of [Active Chiller “Ba” Number Before· Alarming] + Value of [Stopped Chiller “Bs” Number Before Alarmiug] i Val ue of [Normal Active Chiller “Na” Number] + Value of [Normal PCTmOOl (P0iQ856WQQl) - 4-1/5-1

Stopped: Ghiller “Ns” Number] + 'Value Counted Up by Inoperable State Counter C5 for “X" (Expression 5)

In the example shown in FIG.· 8, out of the alignment order foam “1"' to “Sfooftbe cumulative output amount of the engine 60, thu priority value of “X” at the seventh alignment: order “T is expressed by the expression “2” + “0” + “3” + “2” + M” = “8” (see the table, the total value: of the respective shaded values at the second column: “X” from the right and at the rows of steps [2], [3], [4-1, [5] and [lO.!X [0136]

In the example shown in FIG. 8, the. case in which n ~ .:8 is shown. However, the value n is not limited thereto, Any value n may be applied provided that if satisfies- n = 2 to 7 Or n > 0.,.

[0X37] [Embodiment of Present .Invention]

As described above:, in the chiller system 1 according to this embodiment, the operation command is transmitted to one chiller 100 out of the stopped chillers 100 when the following relation is satisfied; [total required operation capacity] Qt / {[number of currently active chillers] N+l) > [partial load capacity] Qp. In other words, the [number of currently active chillers] N is maintained when the [total required operation capacity] Qt is less; than the [referenee load capacity for increasing active chillers] Qi obtained by multiplying the number of the active chillers (N + 1), which is obtained by adding one chiller to the [number of currently active chillers] N, by the [partial load capacity] Qp. On the other hand, the number of the active chillers 100 is increased by one when the [total required operation capacity] Qt is not less: than the [reference load capacity for increasing active chillers] Qi. Thus, it is possible to increase the number of the active chillers 100. before the operation output of: the active chillers reaches 100% output (rated output). Therefore, even when a partial load at which the operation FCimoei (P010856WQ01) < 45/54 output does not reach, the rated output1 is continuously applied, it is possible to suppress the: variation ip. the cumulative operation time among the respective: chiller a 100 fl) to ΙΘΟΐιι), which leads to the chiller system being capable of leveling the respective cumulative operation 5 times of the chillers 100. (l) to 100 (η).

[013:8]

Also, in the chiller system, 1, when the operation command is transmitted: t® one chiller 1.00 Pf the stopped chillers 100 out of the plurality of chillers 100 (l) to 100 (n), the chiller 100 is selected as the 10 target for the next operation: command in the order oh the active chiller 100 in the [before-alarming state]; the stopped chiller 100 in the [before-alarming state]; the active chiller: IQO; in the [normal state]; and the stopped chiller 100 in the [normal state]. In this way, it is possible to select the chiller 100 in the [beforemlarming state] preferentially as the 1,5 target for the next operation command out of the: plurality of chillers 100 (!) to 100 (n), and thus, it is: possible to make the: chiller 100 having a minor abnormality such as a temporary abnormality a maintenance target state in an early stage, Furthermore, if the chillers '1:00 are in. the same state (i,e,, have the same priority), the chiller 100 is selected as 20 the target for the next operation command in ascending order of the cumulative output amount from the initial state or :frpm the time point; at which the predetermined maintenance has been performed, Thus, when the: chillers 100 are in the same state, it is possible to preferentially operate the chiller 100 having a smaller cumulative output amount. 25: Thus, it is possible to level the respective: cumulative operation times of the chillers 100 (l) to 100 inly which reliably allows the chillers 100 Cl) to 100 Cn) to have the same maintenance time.

[0139]

Also, in the chiller system 1, the stop command is transmitted to 30 one chiller 100 Put of the. motive: chillers :1,00 when, the following relation PCTYA091 (P010856WOO 1) - 48/54 is satisfied: [total required operation capacity] Qt / bumber of currently active chillers] N < [partial load capacity] Qp. In other words, the [number of currently active chillers] N is- maintained when the [total required operation capacity] (¾¾ is greater than the [reference load capacity for decreasing active chillers] Qd obtained by multiplying the [number of currently active chillers] N by the [partial load capacity] Qp (i.e., when the [operation capacity per chiller] ia greater than the [partial load capacity] Qp). In contrast, the number of the active chillers; 100 is reduced by one when the [total requited operation capacity] Q.t is not more than the [reference: load capacity for decreasing active chillers] Qd (i.e., when.: the [operation capacity per chiller] is not more than the [partial: load capacity] Qp)· Thus, it is possible to: set the lower limit of the operation capacity per chiller (i.e., the [partial load capacity]; Qp), which prevents the operation in the range of the low operation: efficiency* [OiiOl

Also, in the chiller system 1, when the stop command is transmitted to one chiller 100 of the active chillers 100 out of the plurality of chillers 100 (1) to 100 Cn), the chiller 100 is selected as the target for the next stop command in the order of' the stopped chiller 100 in the [normal state]; the active chiller 100 in the [normal state]; the stopped chiller 100 in the [beforemlarming: state]; and the active chiller 100 in the [heferemlarming state]. In this way, it is possible to select the chiller 100 in the [beforealarming state] preferentially as the target for continuous operation out of the plurality of chillers 100 Cli to 100 in), and thus, it is possible to ;mahe the chiller 100 having a; minor abnormality such as a temporary abnormality a maintenance target state in an early stage. Furthermore, if the chillers 100 are in the same state (i.e., have the same: priority), the chiller 100 is selected as the target for the next stop command in descending order of the cumulative output amount from the initial state or from the time point at which the P0TYAO91 (P01:0856W001) - 47/54 predetermined maintenance has been, performed. Thus, when the chillers 100 are in: the: same state, it is: possible to preferentially stop the chiller 100 having: a greater cumulative- output amount. Thus, it is possible to level the respective cumulative operation times of the chillers 100 Cl) ip 100 (n), which reliably allows the chillers 100 (1) to 100 (n) to have the game maintenance time.

[0141]

The present invention is not limited to: the: above-described embodiments, and. may be embodied in other forms without departing from the gist or essential characteristics: thereof. The: foregoing embodiments are therefore to be considered, in all respects as illustrative and not limiting. The scope of the invention i& indicated by the appended claims rather than by the foregoing description, and all modifications and changes that come within the meaning: and range of equivalency of the claims are intended, to be embraced therein. [0142]

This application claims priority based on Patent Application No. 2014-120486 filed in Japan on June 24. 2014. The entire contents thereof are hereby incorporated in this application by reference.

Industrial Applicability [0143]

The present invention relates to a chiller system in which a plurality of heat pump chillers is connected to each other. The present invention is particularly suitable for leveling respective cumulative operation times of the chillers even When a partial load at which an Operation output does not reach a rated output is: continuously applied.

Description of Reference Numerals [0144] I Chiller system PCTYA091 (P010856W001.) - 48/54 IQ Compressor 11 Clutch 20 Refrigerant-air heat exchanger 30 Refrigerant-air heat exchanger fan. & 40 Expansion valve 41 First e xp-ansion v alv e 42 Second expansion valve 50 Refrigerant-circulating· liquid heat exch 60 Engine 10 70 Engine exhaust heat recovery unit 81 Oil separator 81a Valve 82 Accumulator 83 Receiver 15 100 Chiller 110 Refrig era.nt circuit 111 Four*way valve 112 Bridge circuit 1121 First check valve line 20 1122 Second check valve line 112 a First check valve 112b Second check valve 112c Third check valve 11 2d Fourth check valve 25 113 a High pressure gas refrigerant path 113b First low .pressure gas refrigerant path 113bl Confluence path 113c First gas refrigerant path 113d First refrigerant path. 30 113e High pressure liquid refrigerant path PCTYA091 (P010856W001) - 49/54 XI of First low pressure gas'liquid two phase ϊ 113g Second refrigerant path I13h Second gas refrigerant path 1131 Second low pressure gas'liquid -two phas 113 j Second low pressure gas refrigerant path 120 Coolant path 121 First thermostat type switching valve 122 Second thermostat'type switching valve 123 1 O/f η Radiator 124b Outlet path Inlet path 124c First path 124d Second path 124e Third path 124f Fourth path 124g Fifth path 130 Circulation pump 140 Control device 141 Processor 142 Memory 15.1 First pressure sensor 152 Second pressure sensor 161 First temperature sensor 162 Second temperature sensor 170 Rotation speed sensor 200 Circulating liquid circuit 210 Inlet main pipe 211 Inlet branch pipe 220 Outlet .main, pipe 221 Outlet branch pipe igerant path ifrigerant path PCTYA091 (P010866W001) - 50/54 23.1 Influent circulating liquid temperature sensor 232 Effluent circulating liquid temperature sensor 300 Circulation pump Cl Before-alarming operation counter 5 C2 Before-alarming operation atop counter C3 Normal operation counter

Cl G5 N 10 Pi P2 P3 P4 P5 15 P6 P'/ ο.

Qp Qt

Normal operation stop counter Inoperable state counter Number of currently active chillers First intermediate connection poind Outlet connection point Second intermediate connection point Inlet connection point Confluence point Confluence point Confluence point Reference load capacity for decreasing active chillers Reference load capacity for increasing active chillers Partial load capacity Total required operation capacity PCTYA091 (P010856W001) - 91/54

Claims

ChAlSfS:

1. A chiller system comprising & plurality of heat pump chillers being connected to each other, the plurality of heat pump chillers regulating a temperature of a circulating liquid as a heat medium. for temperature regulation. by condensation heat or evaporation heat of a refrigerant,, wherein, when there is at least one active chiller out of the plurality of chillers, ah operation command is transmitted, to one of the remaining Chillers being Stopped, under a condition that the following relation is: satisfied: [total required Operation capacity] / ([number of currently active Chillers]'+ 1) > [partial load eapacitylj where the [total required operation capacity] represents a total operation capacity required of the at least one active chiller, the {number of currently active chillers] represents a number ox the at least one active chiller, and the {partial load capacity] represents a load capacity of a predetermined partial load.
2, The chiller system according to claim 1, wherein the plurality of chillers is each capable of being in a normal state, an alarming state in which an alarm is being transmitted, or a before-alarming state that is a state between the normal state and the alarming state, wbereih a target chiller for a next operation command is selected in an order of an active chiller in the before-alarming state- a stopped, chiller in the before-alarming state! an active chiller in the normal state ΐ and a stopped chiller in the normal state, and wherein, when the chillers are in a same state, the target chiller for the next operation command is selected in ascending order of a cumulative output amount from an initial state or from a time point at which, a predetermined, maintenance ..has. been performed.
3. The chiller system according to claim 1 or 2. wherein, when there is at least one active chiller out of the plurality of chillers, a stop command is transmitted to. one of the at least one active chiller under a condition that the following relation is satisfied: [total required operation capacity] / [number of currently active chillers] < [partial load capacity];.
4. The chiller system according to claim 3, wherein the plurality of chillers is each capable of being in a normal state, an alarming state in which an alarm is being transmitted, or a before'alarming state that is a state between the normal state and the alarming state, wherein a target chiller for a next stop command is selected in an order of: a stopped chiller in the; normal state; an active chiller in the normal, state ; a stopped, chiller in the before “alarming state »· and an active chiller in the be fore-a! arming state, and wherein:,: when the chillers are in a same State, the target chiller for the next stop command· is selected in descending: order of a cumulative output amount from an Initial state or from a time point at which a predetermined maintenance has been performed.