cooling capacity requirements for a water tank.
cooling capacity requirements for a water tank.
(OP)
Hello,
It is desired to cool down the water of a tank using a chiller (simply an air conditioning unit which evap is placed in the water, a common practice over here) this water is used to cool down compressed air from a compressor, so I understand that BTUs required for initial cooling down from 50 C to 25 C can be simply found from M*Cp*(T2-T1), but I want to know the cooling capacity requirement for continuous cooling (Btu/ Hr) ?? I want this to size the unit which I have to buy for the purpose, a schematic of the system being used is attached FYI.
Thanks a lot.
It is desired to cool down the water of a tank using a chiller (simply an air conditioning unit which evap is placed in the water, a common practice over here) this water is used to cool down compressed air from a compressor, so I understand that BTUs required for initial cooling down from 50 C to 25 C can be simply found from M*Cp*(T2-T1), but I want to know the cooling capacity requirement for continuous cooling (Btu/ Hr) ?? I want this to size the unit which I have to buy for the purpose, a schematic of the system being used is attached FYI.
Thanks a lot.





RE: cooling capacity requirements for a water tank.
Not sure why you're not using the cooling coils to directly cool the air instead, or do some of the cooling using an air/air radiator, but hey, if you want to make life complicated then feel free.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: cooling capacity requirements for a water tank.
can you please explain more ? I want the rate , to compare to the suitable chilling unit (1 Ton , 1 1/2 tons , etc), so how do I use the air data , sorry did not get you
and for the reason behind using this is that originally the unit is a package unit of an air compressor, reciprocating, with inter-stage cooler (air to water), so the water comes from a tank, during last years ambient temp goes really high in summer that the water isn't cold enough to exchange heat with air, so we intend to cool the water, the same system was used long ago to cool water in tanks of other purposes.
RE: cooling capacity requirements for a water tank.
Then convert that to whatever heat flow unit you want to use.
Ton units are usually tons of water per hour, but there is a conversion - just search for it.
I still think there is a more efficient way of cooling air than using an AC machine, but if it's only for occasional use then maybe Ok.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: cooling capacity requirements for a water tank.
for the water inside the tank q = m*cp*dt .... like that iam going to find out Btus required t cool down the water from T1 to T2 ..
then I need to know the rate btu/hr , if I use m*cp*dt again for the air what do I gain from that ?? this equation does not give the rate (per hr or so) right?? isn't it supposed to be the combined heat transfer from water through tank wall to atmosphere ? and using water temp and atmosphere temp ??
sorry again if the question isn't too good but its been really 10 years since I came across heat transfer issue, its not part of our daily projects supervision so I really forgot most of it , and once in a while they throw such a request on me .. so no solution other than asking for help ..
RE: cooling capacity requirements for a water tank.
You could also use mass of water going into and out of the cooler and the Tin and T out of that if you know what that is. Then you have the real heat load going into the water tank.
If your tank volume is big compared to he heat load then maybe it doesn't matter so much?
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: cooling capacity requirements for a water tank.
its just a small tank of volume of 1.57 m3 , not insulated , and your assumption about air in direct contact with water is good, but I still doubt that convection by atmosphere through the tank body to the water inside is important ... I just need to estimate the heat transfer rate after all and the source should be considered.
thnx
RE: cooling capacity requirements for a water tank.
RE: cooling capacity requirements for a water tank.
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers
RE: cooling capacity requirements for a water tank.
RE: cooling capacity requirements for a water tank.
my reply was changed by someone !!! and all my questions are gone, and I got 3 emails notifying 3 new replies, however none are here ?? how could this happen ???????????????????????????????????
RE: cooling capacity requirements for a water tank.
try listing your questions again.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: cooling capacity requirements for a water tank.
thnx
RE: cooling capacity requirements for a water tank.
First I would like to thank you, however I have a few question to ask please (kindly also refer to my attached sketch):
1- I understand that you have not considered the convection between water and tank inner surface as temperature wont really be much different between them, but is that really good practice to do so ? mainly if I have a pump downstream the tank which circulates the chilled water?
2- how do I get the values of HTC for air & water? you have taken 7.5 & 50 , aren't they temperature related?
3- you have assumed a Tsurf = Tin , but later when you calculated power down you calculated Tsurf again, because if Tsurf=Tin then power of conduction in the shell would be zero ?
4- can we use q = A*(Tout-Tin) / (1/HTC1 water) + (thk/kshell) + (1/HTC2 air) ??
5- in the (find power) line , the result iam getting is 1.527 ? kindly correct me if iam wrong
thnx again
RE: cooling capacity requirements for a water tank.
2. thermal conductivity you can look up in tables or literature for your material. convection coefficient is dependent on air circulation, and there are numerous possible values, depending on the geometry and the author. Both are indeed temperature dependent, but unless you are doing something that's radically different, like putting this tank on Venus, or running molten sodium in the tank, it's not that important, particularly as your geometry impact on these coefficients has a larger variance.
3. as notated in the sheet the initial assignment of T.surf is for a guess value to start the solver
4. you can explicitly solve for the temperature, but not that way. you can algebraically manipulate the simultaneous equation above for T.surf to explcitly get an answer. you can see that the end result does not look like your equation
5. based on what? that amount of heat flow is impossible with an uninsulated system.
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers
RE: cooling capacity requirements for a water tank.
RE: cooling capacity requirements for a water tank.
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers
RE: cooling capacity requirements for a water tank.