Thursday, February 10, 2005
About chiller in series
1 ON-OFF CONTROL IN THE "OFF" POSITION:
Note:
Water-cooled, ccntrifugal chillers CC-1 and CC-2 shall bc off, as well as chilled water pump P-1A. Associated condenser water system, including cooling towers and condenser pumps P-1 and P-2 shall also be off.
* Sequence of operation is based on two chillers, each sized for 50% of full cooling load with 42 [degrees] chilled water supply and 60 [degrees] chilled water return.
* Sequence of operation does not include discussion of the condenser water control strategy. Refer to previous Back to Basic Tests #75 and #76 for blow-through cooling tower sequence of operation. Refer to previous Back to Basic Tests #73 and #74 for draw-through cooling tower sequence of operation.
2 ON-OFF CONTROL IN THE "ON" POSITION:
Facility operator shall manually start both chillers unit-mounted "on-off" switches at the associated control panels, CP-1 and CP-2. Interlock control signal shall start chilled water pump P-1A. Associated P-2 shall also start while P-1 waits for control signal from chiller CC-1 to start. Chilled water flow switch FS-1 shall confirm (P-1, P-1A, P-2) is delivering sufficient chilled water flow for CC-1 to start its refrigeration cooling process. Chilled water flow switch FS-2 shall confirm (P-1, P-1A, P-2) is delivering sufficient chilled water flow for CC-2 to start its refrigeration cooling process.
Chilled-water supply temperature control transmitter TT-1, set at (51 [degrees]F, 55 [degrees]F, 60 [degrees]F), shall maintain CC-1 supply water temperature setpoint by signaling CC-1 self-contained, refrigeration controls within its control panel (CP-1, P-1, CT-1).
Chilled-water supply temperature control transmitter TT-2, set at (42 [degrees], 45 [degrees], 50 [degrees]), shall maintain CC-2 supply water temperature setpoint by signaling CC-2 self-contained, refrigeration controls within its control panel CP-2.
3 MINIMUM COOLING:
Chiller CC-2 shall provide minimum cooling capacity with TT-2 maintaining 42[degrees] supply water temperature by modulating the centrifugal (pump, tower, compressor). At minimum load (less than 50%), CC-1 refrigeration cycle shall remain off as chilled water return temperature shall be (42[degrees], 51[degrees], 60[degrees]) or colder. As chilled water demand increase, CC-2 compressor shall continue to produce 42[degrees] chilled water supply up to the full capacity of CC-2 (50% of system capacity).
4 MAXIMUM COOLING:
As the demand for more cooling capacity increases and chilled water return temperature increases above 51[degrees], chiller CC-1 refrigeration cycle shall start. Associated P-1 shall start based on control panel CP-l signal to start CC-1 refrigeration cycle.
Maximum cooling capacity shall be provided by CC-1 and CC-2 in (demand, parallel, series) operation. Temperature transmitter TT-1 shall maintain 51[degrees] chilled water supply leaving CC-1 by modulating its associated centrifugal compressor towards (100%, 50%) capacity. Temperature transmitter TT-2 shall further cool the chilled water supply down to 42 chilled water supply leaving CC-2 by modulating its associated centrifugal compressor towards 100% capacity. In turn, and as demand is reduced, CC-1 and CC-2 compressors shall unload in series while continuing to produce primary 42[degrees] chilled water supply.
ANSWERS FOR CHILLERS IN SERIES WITH CC-2 AS LEAD BASIC SYSTEM -- DESIGN TEST: 2) P-1A; P-1A; 51[degrees]; CP-1; 42[degrees];:3) compressor 51[degrees];4) 100%.Just C&P from web, need to look into it.
Note:
Water-cooled, ccntrifugal chillers CC-1 and CC-2 shall bc off, as well as chilled water pump P-1A. Associated condenser water system, including cooling towers and condenser pumps P-1 and P-2 shall also be off.
* Sequence of operation is based on two chillers, each sized for 50% of full cooling load with 42 [degrees] chilled water supply and 60 [degrees] chilled water return.
* Sequence of operation does not include discussion of the condenser water control strategy. Refer to previous Back to Basic Tests #75 and #76 for blow-through cooling tower sequence of operation. Refer to previous Back to Basic Tests #73 and #74 for draw-through cooling tower sequence of operation.
2 ON-OFF CONTROL IN THE "ON" POSITION:
Facility operator shall manually start both chillers unit-mounted "on-off" switches at the associated control panels, CP-1 and CP-2. Interlock control signal shall start chilled water pump P-1A. Associated P-2 shall also start while P-1 waits for control signal from chiller CC-1 to start. Chilled water flow switch FS-1 shall confirm (P-1, P-1A, P-2) is delivering sufficient chilled water flow for CC-1 to start its refrigeration cooling process. Chilled water flow switch FS-2 shall confirm (P-1, P-1A, P-2) is delivering sufficient chilled water flow for CC-2 to start its refrigeration cooling process.
Chilled-water supply temperature control transmitter TT-1, set at (51 [degrees]F, 55 [degrees]F, 60 [degrees]F), shall maintain CC-1 supply water temperature setpoint by signaling CC-1 self-contained, refrigeration controls within its control panel (CP-1, P-1, CT-1).
Chilled-water supply temperature control transmitter TT-2, set at (42 [degrees], 45 [degrees], 50 [degrees]), shall maintain CC-2 supply water temperature setpoint by signaling CC-2 self-contained, refrigeration controls within its control panel CP-2.
3 MINIMUM COOLING:
Chiller CC-2 shall provide minimum cooling capacity with TT-2 maintaining 42[degrees] supply water temperature by modulating the centrifugal (pump, tower, compressor). At minimum load (less than 50%), CC-1 refrigeration cycle shall remain off as chilled water return temperature shall be (42[degrees], 51[degrees], 60[degrees]) or colder. As chilled water demand increase, CC-2 compressor shall continue to produce 42[degrees] chilled water supply up to the full capacity of CC-2 (50% of system capacity).
4 MAXIMUM COOLING:
As the demand for more cooling capacity increases and chilled water return temperature increases above 51[degrees], chiller CC-1 refrigeration cycle shall start. Associated P-1 shall start based on control panel CP-l signal to start CC-1 refrigeration cycle.
Maximum cooling capacity shall be provided by CC-1 and CC-2 in (demand, parallel, series) operation. Temperature transmitter TT-1 shall maintain 51[degrees] chilled water supply leaving CC-1 by modulating its associated centrifugal compressor towards (100%, 50%) capacity. Temperature transmitter TT-2 shall further cool the chilled water supply down to 42 chilled water supply leaving CC-2 by modulating its associated centrifugal compressor towards 100% capacity. In turn, and as demand is reduced, CC-1 and CC-2 compressors shall unload in series while continuing to produce primary 42[degrees] chilled water supply.
ANSWERS FOR CHILLERS IN SERIES WITH CC-2 AS LEAD BASIC SYSTEM -- DESIGN TEST: 2) P-1A; P-1A; 51[degrees]; CP-1; 42[degrees];:3) compressor 51[degrees];4) 100%.Just C&P from web, need to look into it.
