Affect of Using a 60 Ton Refrig Unit with a Cooler Limited to 30 Tons
Affect of Using a 60 Ton Refrig Unit with a Cooler Limited to 30 Tons
(OP)
I have a system where a rented refrigeration package is rated at 60 Tons, consisting of a refrigerant cooling a brine solution. The brine solution is pumped to a shell & tube cooler which cools a process fluid storage tank via a recirculating pump. An excel model of the cooler shows the cooler is limited to 30 Tons by the existing tube length of 12 ft; if I try to increase the overall heat transfer coefficient U by increasing brine flow, then the cooler is limited by the brine pressure drop on the shell side; above 30 Tons the required brine flow is beyond the capability of the pump system. The excel model duplicates the design conditions and has been confirmed with Aspen.
I have asked for flow and temperature in and out of the shell and tubes for the cooler to further confirm the 30 Ton coil length limitation.
My question is, what will the T/S and P/H Diagrams look like for the Refrig Unit for the actual run condition?
Will it be somehere between the design 60 ton condensing and evaporating pressure and temperature? Will both of these pressures rise? What happens to the refrig unit under the condition I have described? Can I calculate run condition?
I am interested in this because we can save money renting a 30 Ton unit instead of the 60 Ton unit; or I can purchase our own facilities at a reduced cost.
I have asked for flow and temperature in and out of the shell and tubes for the cooler to further confirm the 30 Ton coil length limitation.
My question is, what will the T/S and P/H Diagrams look like for the Refrig Unit for the actual run condition?
Will it be somehere between the design 60 ton condensing and evaporating pressure and temperature? Will both of these pressures rise? What happens to the refrig unit under the condition I have described? Can I calculate run condition?
I am interested in this because we can save money renting a 30 Ton unit instead of the 60 Ton unit; or I can purchase our own facilities at a reduced cost.
The more you learn, the less you are certain of.





RE: Affect of Using a 60 Ton Refrig Unit with a Cooler Limited to 30 Tons
RE: Affect of Using a 60 Ton Refrig Unit with a Cooler Limited to 30 Tons
If you don't have capacity control mechanism, then the actual cycle will be shifted down from the theroretical cycle.
It is better to go for 30 ton unit.
You can calculate actual cycle, if you know suction and discharge pressures, condensing and evaporating temperatures and subcooling and superheat.
Regards,
RE: Affect of Using a 60 Ton Refrig Unit with a Cooler Limited to 30 Tons
The more you learn, the less you are certain of.
RE: Affect of Using a 60 Ton Refrig Unit with a Cooler Limited to 30 Tons
Regards,
RE: Affect of Using a 60 Ton Refrig Unit with a Cooler Limited to 30 Tons
you must be a process engineer, given the detailled decription you gave of your installation. It is obvious that your process is not very well balanced. A 60 Ton condensor capacity , with only 30Ton evaporating capacity , taken some heat transfer losses in between both end users , means that your compressor + brine installation is severely underused , and you are paying lots of money for renting a not frequently operating condensing unit.
I would start by balancing the condensor unit to the end evaporator , or if your end evaporator is too small , increase the evaporating capacity to a correct level and then reduce condensing capacity to match the new end evaporating capacity + intermediate heat losses occuring between the various transfer mediums.