bersaga
21-01-2003, 08:42 AM
Need some views on condensor selection :
The system is using compound 2-stage compressors ( T evap = -35 deg and Tcond = 40 deg C ) Its an NH3 system. (Ambient is 35 deg C) Calculated heatload is 160 kW. Thinking of using two compressors - MYCOM N62WB that gives a capacity of 92.4kW and absorbed power of 54.4kW each at the said operating conditions. In order to cater for pulldown load and defrost cycles, I have selected a water-cooled condensor of about 600kW .
Normally, I would look at the compressor operating envelope and check both the refrigerating capacity and the absorbed power at the highest evaporating temperature - in the case of a Bitzer 2-stage , it is -20deg C - sum both and select the condensor accordingly higher.
MYCOM catalogues or software do not give operating envelopes. Taking pulldown load as 3 times the normal operating load gives the following : ( 92.4 + 54.4 ) x 3 + ( 92.4 + 54.4) = 587.2 kW ( select 600 kW)
Is the condensor oversized ? Learned views deeply appreciated!:)
The system is using compound 2-stage compressors ( T evap = -35 deg and Tcond = 40 deg C ) Its an NH3 system. (Ambient is 35 deg C) Calculated heatload is 160 kW. Thinking of using two compressors - MYCOM N62WB that gives a capacity of 92.4kW and absorbed power of 54.4kW each at the said operating conditions. In order to cater for pulldown load and defrost cycles, I have selected a water-cooled condensor of about 600kW .
Normally, I would look at the compressor operating envelope and check both the refrigerating capacity and the absorbed power at the highest evaporating temperature - in the case of a Bitzer 2-stage , it is -20deg C - sum both and select the condensor accordingly higher.
MYCOM catalogues or software do not give operating envelopes. Taking pulldown load as 3 times the normal operating load gives the following : ( 92.4 + 54.4 ) x 3 + ( 92.4 + 54.4) = 587.2 kW ( select 600 kW)
Is the condensor oversized ? Learned views deeply appreciated!:)