Can one ref-compressor unit be used to have 2 independent temperatures
Can one ref-compressor unit be used to have 2 independent temperatures
(OP)
Hi,
I am involved in fishing boat refrigeration units and I have a doubt. If some of you could help me in this it will be great!
The design requirement is to cool two compartments at two different temperatures to be controlled independently.
The two compartments and the temperatures are:
Fish hall : -16 oC
Chill bath : -1 oC
I am in need of using a single compressor-condenser unit for this application.
I am thinking of using two evaporators with expansion valves and individual temperature controllers for each cabin which will ON-OFF the ref-supply to each evaporator using solenoid controlled ON-OFF valves.
Compressor will run continuously and only OFF if both evaporator coolent supply valves are closed as a result of required temperature achievement.
Is this possible and practiced?
What issues will rise?
or Do I have to revert back to 2 individual compressor systems for each cabin?
Thanks.
I am involved in fishing boat refrigeration units and I have a doubt. If some of you could help me in this it will be great!
The design requirement is to cool two compartments at two different temperatures to be controlled independently.
The two compartments and the temperatures are:
Fish hall : -16 oC
Chill bath : -1 oC
I am in need of using a single compressor-condenser unit for this application.
I am thinking of using two evaporators with expansion valves and individual temperature controllers for each cabin which will ON-OFF the ref-supply to each evaporator using solenoid controlled ON-OFF valves.
Compressor will run continuously and only OFF if both evaporator coolent supply valves are closed as a result of required temperature achievement.
Is this possible and practiced?
What issues will rise?
or Do I have to revert back to 2 individual compressor systems for each cabin?
Thanks.





RE: Can one ref-compressor unit be used to have 2 independent temperatures
RE: Can one ref-compressor unit be used to have 2 independent temperatures
If you only have one system, all "cold" is generated based on the lower efficiency for the lower temperature.
Two independent systems may be more economical since the -1°C system will be much more efficient.
RE: Can one ref-compressor unit be used to have 2 independent temperatures
The key concept missed is redundancy. Putting all the eggs in one basket will be a huge blunder! saving a few dollars up front will cost many more lost later on an application that screams DIFFERED MAINTENANCE.
RE: Can one ref-compressor unit be used to have 2 independent temperatures
The issues raised in other replies of efficiency and reliability must also be addressed. I presume from your fishing boat remark that this system will be giong to sea. In which case, two compressors woud be best from reliability/availability stand point. An enhancement of this is to use both compressors to service both spaces. Use advanced control system (PLC) to detect which space is on and run variable suction pressure set points to maintain most efficient operation.
Mark Hutton
RE: Can one ref-compressor unit be used to have 2 independent temperatures
1 compressor, 1 condensor
compressor on/off cycle defined by lowest temperature
(vapour pressure @ -16 degC)
1 evaporater and expansion valve with its temp. bulb on outlet evaporator (4 degC superheated = -12 degC)
1 evaporater and expansion valve with its temp. bulb on outlet evaporator (4 degC superheated = 3 degC)
between this evaporator and the common return line to compressor (suction) there will be a pressure regulating valve, keeping the evaporator pressure equal to the vapour pressure @ -1 degC