Results 101 to 150 of 152
Thread: Liquid Overfeed Systems
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22-08-2006, 04:11 PM #101
Re: Liquid Overfeed Systems
Hi corineramer,
Use this link to review vessel information.
http://www.evapco.com/media/pdf/asme-pressure.pdf
...the cycle that we have studied is the vapor compression cycle
If you try to add other coils which are operating at higher evaporting temperatures, you would need back-pressure valves on those coils operating at the higher temperatures (greater than -30C).
This really complicates a liquid overfeed system and the explanation of how it operates.
If this is supposed to be a school project your professor has actually given you one of the hardest problems to work on.
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23-08-2006, 03:24 AM #102
Re: Liquid Overfeed Systems
Hi US Iceman,
I'm a groupmate of corineramer. We are really confused about the liquid overfeed refrigeration system. This is what we understand about it.
You will supply more liquid refrigerant flowrate in the evaporator than required to enchance heat transfer by providing a higher velocity in the coils.
In our subject, we need to design a refrigeration system(liquid overfeed) for ice cream manufacturing plant.
We have used a separate refrigeration system for each process, freezing, hardening, storage.
Our professor said that we can tap the discharge line in the compressor because it has the same discharge pressure.
Is it possible if we only have 1 to 2 condenser? is it possible if we only have one condenser and 3 expansion valve?
Back to liquid overfeed. for example, in our freezing process, we have a -10 degree C ammonia. The ammonia pump will pump the refrigerant to the evaporator and increase the pressure of the refrigerant thus increaseing the boiling point. So we need the hand expansion valve to bring back the saturation pressure at -10 degree C? In liquid overfeed, the refrigerant that comes out from the evaporator is a mixture of liquid refrigerant and vapor right? then it will go to the separator to separate liquid and vapor. Then the compressor will suck the vapor at saturation pressure of the -10 degree C. The discharge pressure will depend on the ambient temperature in the condenser. We have a 35 degree C. Then after passing in the condenser, it will pass to the expansion valve to bring down the pressure to the saturation pressure at -10 degree C then stored in the liquid receiver for use when the level of refrigerant in the separator is low. is this correct?
Sorry if we ask so many question, we are really confused and thank you so much for spending time and helping us. Thanks
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23-08-2006, 09:39 AM #103
Re: Liquid Overfeed Systems
Originally Posted by ipelatak
http://www.hysave.com/
and click on 'live demo'
which is a small vid of the process..however each case needs careful examination and application which I understand is where they badly went wrong in the early days..
cheers
richard
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23-08-2006, 02:43 PM #104
Re: Liquid Overfeed Systems
hi us iceman,
BTW ipelatak is my groupmate... his message is the one after your latest post pls read his message, tnx... actually our professor told us to pick an industrial plant and design one of its utilities so that it would be easier for us because if he would choose what we're gonna design then it will be very difficult but unfortunately we picked a hard one not the easy ones... we have problems in selecting the compressor because our reference is the suction pressure, is this correct? for example our suction is 42.3psig and discharge press is 190psig... our prof told us to base our compressor to this given data but when im looking for the compressor they are giving the refrigeration capacity not the pressure... is this correct? or convert the TOR to refrigerating capcity and use it in selecting the compressor.. we're really confused... sorry if we'er disturbing you..
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23-08-2006, 03:24 PM #105
Re: Liquid Overfeed Systems
Hi kurimaw & latek,
Expansion valve before liquid reciever is WRONG!
I think you should go back from the very basic of refrigeration before jumping out for the design. You shoul know the function of every components of refrigeration.
Are you a first year college student? what school?
Don't rely too much in your prof. you should do your own researh & study.
Regards,
Guapo
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23-08-2006, 03:48 PM #106
Re: Liquid Overfeed Systems
Hi ipelatak,
Originally Posted by ipelatak
In a DX system, you loose some of the capacity of the evaporator due to the need to provide superheat. If you look at the evaporator ratings you will see a DX coil has about 15% less capacity than the same coil for liquid overfeed.
Originally Posted by ipelatak
Originally Posted by ipelatak
Originally Posted by ipelatak
You are correct about the increase in boiling temperature. The added pressure generated by the pump actually seems similar to subcooling of the liquid. Therefore, the liquid will not boil until the pressure is reduced. The hand expansion valve is really a balancing valve. You are using it to adjust the flow rate into all of the evaporators.
Originally Posted by ipelatak
The discharge pressure will depend on the ambient conditions and the capacity of the condenser. If you are using an evaporative condenser, you are concerned with the condensing temperature and entering wet bulb temperature of the air.
Originally Posted by ipelatak
I'm not sure whay you have an expansion valve after the condenser as you described. (Note: I have done something like this before, but quite different than what you are describing.
Originally Posted by ipelatak
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23-08-2006, 04:41 PM #107
Re: Liquid Overfeed Systems
Hi US iceman,
Originally Posted by US Iceman
So after condenser, we should put a high pressure liquid reciever. The temp of the refrigerant is 35 degree C = to the ambient temperature of the condenser. When the level in the separator begins to decrease, a control system will allow liquid from the high-pressure receiver to flow into the separator to maintain the liquid level. The temp in the separator is -10 degree C and the temp in the high pressure reciever is 35 degree C. We thought we need a expansion valve to bring back the pressure and temperature of the refrigerant in high pressure reciever equal to the refrigerant's temp and pressure in the separator.
Do we still need a pump after the high pressure reciever or the pressure will transport the refrigerant back to the separator and bring back the temperature and pressure because of the pressure drop in the pipe?
thanks a lot masters, were really thankfull that you guys are helping us. thanks a lot
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23-08-2006, 04:41 PM #108
Re: Liquid Overfeed Systems
Hi corineramer,
I had a long explanation of the compressor rating procedures written out and when I tried to post it, something happened and I lost the whole thing.
The short version is:
You have to include the suction and discharge pressure losses to correct for the actual compressor performance.
Discharge pressure = condensing pressure + piping pressure lossses
Suction pressure = evaporating pressure - piping pressure losses
Convert the suction and discharge pressure to their equivalent saturation temperatures. These are the temperatures you want to use for selecting the compressors.
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23-08-2006, 04:52 PM #109
Re: Liquid Overfeed Systems
Originally Posted by ipelatak
We thought we need a expansion valve to bring back the pressure and temperature of the refrigerant in high pressure reciever equal to the refrigerant's temp and pressure in the separator.
Do we still need a pump after the high pressure reciever...
The refrigerant pump in an overfeed system is under the separator and operates at suction pressure.
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23-08-2006, 10:15 PM #110
Re: Liquid Overfeed Systems
Hi
Originally Posted by ipelatak
Originally Posted by corineramer
To obtain needed capacity, compressor capacity is very important but power of motor also.
Hope this will help a little
Best regards, Josip
It's impossible to make anything foolproof because fools are so ingenious...
Don't ever underestimate the power of stupid people when they are in large groups.
Please, don't teach me how to be stupid....
No job is as important as to jeopardize the safety of you or those that you work with.
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24-08-2006, 12:12 AM #111
Re: Liquid Overfeed Systems
Ahh, crap... Know I see. You guys are designing a Hysave system. That is not a liquid overfeed system, it's a DX system.
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24-08-2006, 02:38 AM #112
Re: Liquid Overfeed Systems
Hi,
I based my condenser designed to 45C, you will have a very huge condenser if you based on 35C.
Ambient is already 28-34C.
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24-08-2006, 04:43 AM #113
Re: Liquid Overfeed Systems
Hi Dan,
Here is why I thought the discussion took a different turn of events:
Originally Posted by ipelatak
The post that Mr. Bartlett made did not really have anything to do with a liquid overfeed system, other than it uses a refrigerant pump. Different system, different reason.
Originally Posted by Dan
I guess I made some assumptions too. I should have asked what type of condenser they are using. I assumed they were evaporative condensers, since it was an ammonia system.
I just hope the students are beginning to understand this type of system. An overfeed system is not hard to understand, but it sounds like their professor has told them some conflicting information.
I think we can get them to understand this, but I'm not sure if they have enough time before their school project is due.
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24-08-2006, 06:05 PM #114
Re: Liquid Overfeed Systems
Hi to all,
Sorry if we make some confusion in what we said in the previous posts.
This is what we understand so far, pls correct us if we're wrong.
New example:
Ambient temp = 34C
Condensing temp = 45C
Evaporating temp = -10C
The liquid refrigerant in the separator is at -10C. The refrigerant will be pumped by a ammonia centrifugal pump. The pump will supply more liquid refrigerant into the evaporator than the amount that boils off.
The pump provides the pressure to transport the liquid refrigerant. The pump will increase the pressure of the refrigerant thus increasing the boiling point so
we need a hand expansion valve to bring back the saturation pressure of the refrigerant.
The liquid refrigerant will pass through the evaporator and leaves at the same temperature of -10C but a mixture of liquid and vapor. The mixture of the refrigerant will go to the Separator to separate the liquid refrigerant and the vapor refrigerant.
The vapor refrigerant at -10C will be sucked by the ammonia compressor. The discharge pressure of the ammonia compressor will be the pressure of ammonia at the ambient temperature in the condenser.
The refrigerant will be condensed at 45C by a water-cooled condenser. The refrigerant still under high pressure leaves the condenser and passes to a high-pressure receiver where it is stored for later use for supply in the separator.
We expansion device after the high-pressure receiver to feed the liquid into the separator to maintain the liquid level. The liquid comes from the reciever at 45C, goes through the expansion valve, into the separator.
what are the valves we need and where to place them? sorry out professor didnt taught us how
to do this.
Uhm.. if you have some free time, can you pls tell us how liquid overfeed works?
In getting the mass flowrate in the system
mass flowrate of refrigerant (latent heat of vaporization ammonia) = Heat added by the
evaporator
Sizing of compressor
Suction pressure = Psat at -10C, ammonia
Discharge pressure = Psat at 34C(ambient temp), ammonia
work of compressor = m(delta h), mass flowrate (enthalpy at 34C - enthalpy at -10C)
Sizing of condenser
Condensing temp = 45C
Heat rejected = work of compressor + heat added by the evaporator
Cooling tower
Air temp in = 32 C
temp of water in reservoir = 34C
temp of water entering condenser = 34C
temp of water leaving condenser = 50C
water flowrate
water flowrate (sp. heat water) (50C - 34C) = Heat rejected by condenser
Sorry if we ask so many, thanks for all your help and thanks for spending time with us. thanks masters.
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24-08-2006, 07:23 PM #115
Re: Liquid Overfeed Systems
It's not one of my strong points (ammonia) but some of this needs explaining to be able to understand.
The discharge pressure of the ammonia compressor will be the pressure of ammonia at the ambient temperature in the condenser.
The refrigerant will be condensed at 45C by a water-cooled condenser.The liquid comes from the reciever at 45C, goes through the expansion valve, into the separator.
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24-08-2006, 07:54 PM #116
Re: Liquid Overfeed Systems
Originally Posted by ipelatak
The discharge pressure of the ammonia compressor will be the pressure of ammonia at the ambient temperature in the condenser.
The refrigerant will be condensed at 45C by a water-cooled condenser. The refrigerant still under high pressure leaves the condenser and passes to a high-pressure receiver where it is stored for later use for supply in the separator.
We expansion device after the high-pressure receiver to feed the liquid into the separator to maintain the liquid level. The liquid comes from the reciever at 45C, goes through the expansion valve, into the separator.
sorry our professor didnt taught us how to do this.
The mass flow calculations are a little complicated for an overfeed system. It is different in various parts of the system.
In general terms, the liquid supply to the separator provides sufficient liquid to maintain the level. The refrigerant that boils off in the evaporator is this amount.
The refrigerant pump circulates about 300-400% this amount to the evaporator. The 300-400% mass flow is flowing through the liquid line from the pumps, to the evaporator, and back to the separator.
I think you are getting the idea.
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24-08-2006, 09:02 PM #117
Re: Liquid Overfeed Systems
Hi,
Originally Posted by ipelatak
http://www.danfoss.com/Asean/Products/Categories/
http://www.danfoss.com/Pacific/Busin...+Conditioning/
here you can find all products you need for refrigeration or AC plant. There you can find also some brochures and so on...
Here you can find almost all you need valves, systems&vessels, accessories
http://haphillips.com/
http://haphillips.com/products.html?pc=67#77
Pls, don't show that to your professor
Hope this will help to finalize your project on time
Best regards, Josip
It's impossible to make anything foolproof because fools are so ingenious...
Don't ever underestimate the power of stupid people when they are in large groups.
Please, don't teach me how to be stupid....
No job is as important as to jeopardize the safety of you or those that you work with.
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25-08-2006, 03:10 AM #118
Re: Liquid Overfeed Systems
Originally Posted by us iceman
Originally Posted by us iceman
Originally Posted by us iceman
the flow will be the same at the separator to pump, pump to hand ex to evaporator to separator.
In separator (vapor) to compressor to condenser to high-pressure liquid reciever.
High-pressure receiver to ex valve to separator.
Originally Posted by us iceman
Originally Posted by josip
haha dont worry, we wont
Thanks alot masters, ur our savior. thanks for spending time with us and for helping us. can we ask again if we have a problem somewhere again in our project? thanks master us iceman, master josip and to allLast edited by ipelatak; 25-08-2006 at 03:16 AM.
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25-08-2006, 03:56 PM #119
Re: Liquid Overfeed Systems
Originally Posted by ipelatak
From the refrigerant pump to the hand expansion valve, to the evaporator, and back to the separator the mass flow is higher. This is where the mass flow will be about 3 or 4 times higher than the other part of the system.
The mass flow from the separator (gas) to the compressor, to the condenser, to the receiver and out to the hand expansion valve on the separator (maintaining the liquid level) is based on the mass flow that boils off in the evaporator, PLUS...
The flash gas that is generated when the 45C liquid flashes off down to 10C, which is being fed into the separator to maintain the liquid level.
So, what you have coming out of the separator as gas (back to the compressor) is the flash gas + the gas boiled off in the evaporator coils.
The excess liquid that is not boiled off in the evaporator, just simply recirculates. Someone may say you need to recirculate more liquid than 3-4 times what boils off.
I say you can design the system for less, so you do not have to pump as much liquid. We will save that discussion for another time.
It sounds like you guys are getting close to being finished. I hope you get a big A++ on your project.
Best Regards,
US Iceman
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26-08-2006, 06:48 AM #120
Re: Liquid Overfeed Systems
The flash gas that is generated when the 45C liquid flashes off down to 10C, which is being fed into the separator to maintain the liquid level.
So, what you have coming out of the separator as gas (back to the compressor) is the flash gas + the gas boiled off in the evaporator coils.
we're still confused in getting the compressor capacity because we have computed it using the enthalpy differencence between the discharge and suction times the mass flowrate(we assumed that the refrigerant that will vaporize in the evaporator is 25% of the overfeed massflowrate of the refrigerant that enters the evap. we havnt included the mass of the flash gas) is this correct??
BTW our overfeed is 400%
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26-08-2006, 12:57 PM #121
Re: Liquid Overfeed Systems
I'm stuck without my refrigerant tables but using steam as an example, I think this should help if I remember this right (sounds of scraping around in dusty corners of brain....)
Flash gas is the excess heat energy caused by the reduction in pressure. So for steam condensate:
7 bar = 721kj/kg
0 bar = 419kj/kg
Excess = 302kj
So the percentage of flash gas is:
(excess/enthalpy of evaporation kj @ 0 bar) x 100%
(302kj/2258kj) x 100% = approx 13%, or 13kg of gas and 87kg of liquid.
(Enthalpy of evaporation is the term that is now used for latent heat).
So if you know your mass flow in kg through the regulator, you should be able to work out the amount of flash gas your compressor needs to deal with.
Steve
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26-08-2006, 01:15 PM #122
Re: Liquid Overfeed Systems
hi to all,
pls correct me if im wrong... what we did is, we calculate the percentage or quality by this equation: h= hf+xhfg
this equation is from thermodynamics.. are we correct???
also how can we measure the mass of the gas that leaves the evaporator?
do the latent heat ammonia vary in different temp???
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26-08-2006, 01:57 PM #123
Re: Liquid Overfeed Systems
Originally Posted by corineramer
Originally Posted by corineramer
In simple terms, you supply say 0.05 kg/second of liquid to the evap and it will expand to produce say 0.05m3/hr of vapour. That vapour density at the evaporating pressure can be found in your refrigerant properties table.
This means your compressor will need to deal with 0.05m3/hr from the evap plus flash gas generated at the hand regulator.
Originally Posted by corineramer
Steve
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26-08-2006, 03:12 PM #124
Re: Liquid Overfeed Systems
Originally Posted by corineramer
Where,
hf = liquid enthalpy at evaporating pressure/temperature
hg = vapor enthalpy at evaporating pressure/temperature
hfg = latent heat at evaporating pressure/temperature
Originally Posted by corineramer
Now, if you calculate the refrigerant mass flow into the separator, you need to use the conditions that exist for the compressor.
hf = liquid enthalpy at condensing pressure/temperature
hg = vapor enthalpy at evaporating pressure/temperature
When you find the mass flow for one kW (or 1 Ton) using the above NRE (Net Refrigerating Effect), hg-hf, you will find this mass flow is higher than the mass flow for the evaporator (for a 1 kW or 1 Ton basis).
The difference between the two mass flows (compressor mass flow minus evaporator mass flow - gas only) is the flash gas.
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26-08-2006, 05:10 PM #125
Re: Liquid Overfeed Systems
Hi to all,
Example
evaporator cooling capacity = 178.2637 KW
Temp of ammonia in separator = -10C
Condensing temp of ammonia = 40C
For evaporator mass flow for gas
From ammonia table at -10C
hf = 135.4 KJ/kg
hg = 1433 KJ/kg
hfg = hg - hf = 1433 - 135.4 = 1297.6 KJ/kg
Mass evap gas = (178.2637 KJ/sec)/1297.6 KJ/kg
= 0.13738 kg/sec
For compressor mass flow for gas
From ammonia table at 40C (condensing temp)
hf = 371.9 KJ/kg
From ammonia table at -10C (evaporating temp)
hg = 1433 KJ/kg
hfg = hg -hf = 1433 - 371.9 = 1061.1 KJ/kg
Mass comp gas = (178.2637 KJ/sec)/1061.1 KJ/kg
= 0.16800 kg/sec
Mass comp gas = Mass evap gas + Mass flash gas
Mass flash gas = Mass comp gas - Mass evap gas
= 0.16800 - 0.13738
= 0.03062 kg/sec
Pls correct us if we're wrong
In getting the mass flowrate with overfeed of 400%
= mass evap gas x 4
= 0.13738 kg/sec x 4 = 0.54952 kg/sec
In getting the volume flowrate with overfeed
from ammonia table at -10C
vf = 1.5338 L/kg
Vol. flowrate = 0.54952 kg/sec x 1.5338 L/kg
= 0.84285 L/sec
In getting the work of compressor, Wc
Suction pressure, Ps = Psat at -10C
From ammonia table at -10C
Ps = 2.908 Bar or 290.8 KPa
hg = 1433 KJ/kg
Discharde pressure, Pd = Psat at 40C
From ammonia table at 40C
Pd = 15.54 Bar or 1554 KPa
hg = 1473.3 KJ/kg
Wc = Mass comp gas x (hg at 40C - hg at -10C)
= 0.16800 kg/sec (1473.3 KJ/kg - 1433 KJ/kg)
= 6.7704 KW
pls correct us if we're wrong.. thanks masters
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29-08-2006, 12:14 PM #126
Re: Liquid Overfeed Systems
hi to all,
i have a question in our ageing process... we have to maintain the temp of our product to 4C... we're confused in getting the load because there's no temp difference... but we're to maintain this temp... how can we get the load in order for us to select the equipment.. we will use a water chiller in maintaining this temp... pls help, tnx
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29-08-2006, 01:31 PM #127
Re: Liquid Overfeed Systems
Load comes from heat. Your product will heat up by respiration (biological activity) and heat will leak into the cooled space (heat transmission). Your refrigeration should carry away this heat. Heat will also come from any lights, fans, or people in the cooled space. Even if you load your product in at 4c, it will warm up eventually.
You have to work out this heat load and this information is readily available in text books and on the internet.
In simple terms, you have to work out the equipment needed to carry away this heat and from this you get your equipment requirements. Look for water chiller suppliers and download their information. A water chiller will be rated in kW and you need to supply it with enough refrigerant and enough water to move the heat.
Steve
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29-08-2006, 02:33 PM #128
Re: Liquid Overfeed Systems
Originally Posted by corineramer
If you use a high temperature range (larger TD for the water), the flow rate will be smaller (smaller water pump).
A lower temperature range (smaller TD for the water), the flow rate will be much higher (larger water pump).
Depending on what you select for the supply chilled water temperature to the coil(s) and the return water temperature (from the coils), you are finding the TD required. This is a balance between the requirements of the cooling process and the costs of the equipment (operating and initial equipment costs)
When you have the temperature range and flow rate established, then you can select the evaporating temperature for the chiller.
Once this is completed, you have the load and the evaporating temperature, so now you can add this to the refrigeration capacity requirements and select the chiller.Last edited by US Iceman; 29-08-2006 at 02:37 PM. Reason: added text
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30-08-2006, 11:11 AM #129
Re: Liquid Overfeed Systems
hi us iceman,
im selecting the the compressor using the grasso site that you gave... what does refrigerating capacity at 2940 min^-1 mean??? min raised to -1, what does it stand for?Last edited by corineramer; 30-08-2006 at 11:18 AM.
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30-08-2006, 11:29 AM #130
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30-08-2006, 11:30 AM #131
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30-08-2006, 02:29 PM #132
Re: Liquid Overfeed Systems
Originally Posted by corineramer
However, I did want to clarify the statement itself.
When the Grasso literature says capacity at 2940 RPM, are they stating the kW (refrigeration) at 2940 RPM? Or, does the literature list cubic meters per hour?
Capacity is kW (or Tons), not m^3/hr. You may have already seen this, but I wanted to point out the fact that you must read the small notes sometimes hidden in the technical information.
The other issue that sometimes gets overlooked is the use of subcooling. Some manufacturers will use subcooling on ammonia compressors to inflate the performance values quoted.
Very seldom will you find subcooling from the condenser in an ammonia system, IF THE CONDENSER IS PIPED CORRECTLY.
Capacity is capacity, but you have to be careful on how the manufacturer states you will get that capacity at a specific operating condition.Last edited by US Iceman; 30-08-2006 at 02:46 PM. Reason: text editing
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30-08-2006, 02:56 PM #133
Re: Liquid Overfeed Systems
Generally, capacity is directly proportional to swept displacement and (that is the same) to rotational speed.
2940rpm is the synchro speed for 50Hz asynchronous three-phase 2-poles motors (50/s x 60 s/min = 3000/min), but at 60Hz it is more likely to be 3520 rpm, with a net increase in capacity of 20%.
Which is why capacity is specified together with the swept volume or rotational speed.Last edited by NoNickName; 30-08-2006 at 02:57 PM. Reason: Clarity of terms
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31-08-2006, 12:51 AM #134
Re: Liquid Overfeed Systems
Originally Posted by NoNickName
In general terms though, I agree with what you said. But in no way did I intend to make a point that the capacity does not change with speed.
corineramer, here is a little equation to help you with this...
(Hz X 120)/ number of motor poles = nominal RPM
Here is an example:
(50 Hz X 120)/4 pole motor = 1500 RPM
(60 Hz X 120)/4 pole motor = 1800 RPM
(50 Hz X 120)/2 pole motor = 3000 RPM
(60 Hz X 120)/2 pole motor = 3600 RPM
The actual full load RPM will be slightly less than this due to slippage of the rotor in the stator. I thought this might help you understand the relationship with motor speed, Hertz, and motor construciton.
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31-08-2006, 06:18 AM #135
Re: Liquid Overfeed Systems
hi,
thanks for that info... us iceman where can i get a clearer drawing of the evapco horizontal recirculator system?? we need it for our lay out, we're gonna use cad in drawing it... right now im selecting the equipments and following the procedure in the brochures but i dont know if im doin it right.. hehehe.. tnx again for the big help
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31-08-2006, 03:03 PM #136
Re: Liquid Overfeed Systems
Hi corineramer,
Try this as an example to start with. This example is for an open drive refrigerant pump, not a hermetic pump.
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31-08-2006, 03:43 PM #137
Re: Liquid Overfeed Systems
hi us iceman,
thank you so much sir... u have contributed a lot to our work... just a little push and where nearly finished..
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31-08-2006, 10:36 PM #138
Re: Liquid Overfeed Systems
I'm glad to help you guys.
Push, push, push.... Did that help you get the project done?
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01-09-2006, 05:30 PM #139
Re: Liquid Overfeed Systems
hi us iceman,
yup!! nearly, we dont know bout the piping because there are a lot of things that we dont know yet, like the inclination of hte pipes the oil traps that must be "u" shape.. i saw it in the brochure.. we're not famaliar with that but will solve it, hehehe also do u have the price of surge drum, cooling towet and evaporative condenser of the EVAPCO??Last edited by corineramer; 01-09-2006 at 05:47 PM.
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01-09-2006, 09:53 PM #140
Re: Liquid Overfeed Systems
Originally Posted by corineramer
Originally Posted by corineramer
But, it is nice to hear you are making progress. Keep up the good work.
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03-09-2006, 09:59 AM #141
Re: Liquid Overfeed Systems
hi us iceman,
yup, we also managed to get a hold of an ASHRAE copy for the sizing of the pipes, hehehe... we'll have to read it...
do u know where can we find a tunnel freezer for ice cream and filling machine?? i didnt like the one that we got because im not sure about the sanitary and its second hand.. its for the quality.. as for the filling machine we need to fill them in our container... our ice cream does not come on sticks and wrapper.. its in bulk cans..
thank you so much! rock on!!!\m/
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03-09-2006, 09:30 PM #142
Re: Liquid Overfeed Systems
Originally Posted by corineramer
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04-09-2006, 02:08 PM #143
Re: Liquid Overfeed Systems
hi us iceman,
ok tnx.. i'll just pm them...
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07-09-2006, 02:20 PM #144
Re: Liquid Overfeed Systems
hi us iceman,
do u know something that can help us in piping our ammonia system??
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07-09-2006, 02:47 PM #145
Re: Liquid Overfeed Systems
What is your question? I will try to answer them...
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09-09-2006, 12:26 PM #146
Re: Liquid Overfeed Systems
hi us iceman,
for the suction diameter of the compressor and outlet diameter of the low pressure receiver are different... we dont know how to size them? our equipments have different diameters.. how can we pipe them? by using the larger diameter or the smaller or you can calculate for it??
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09-09-2006, 04:40 PM #147
Re: Liquid Overfeed Systems
Always calculate the pipe size you need. The connections put on the equipment is the manufacturers attempt at balancing cost versus requirements.
When you are designing the system you have to know the operating conditions for each piece of equipment.
Let's look at an evaporator...
If the evaporator is selected for a specific evaporating temperature, then you will have some pressure loss (due to flow) to the next piece of equipment. The difference in pressure between these two components is determined by the mass flow and pipe size.
If the pipe is too small, you will have a higher pressure loss.
If the pipe is larger (for the same mass flow), the pressure loss will be reduced.
The pressure at the end of this pipe will affect the performance of that device.
I never recommend using the connection size as the required pipe size.
You do have to connect the pipe to the two components, so what you want to find is the required pipe size based on allowable pressure loss (this is what you use for your system design and equipment selections).
After you know the required pipe size, you will probably find that you will need some pipe reducer fittings to make the terminating connections.
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12-09-2006, 08:29 AM #148
Re: Liquid Overfeed Systems
hi us iceman,
how can we compute for the amount of ammonia in the system??? what im trying to do is get the volume of the low pressure receiver and then multiply it with the density of ammonia and try add them up.. is this right?
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12-09-2006, 05:33 PM #149
Re: Liquid Overfeed Systems
Volume of system X density = mass
You have to be careful if the volume you use is either gas or liquid (or both in a two phase line).
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25-09-2006, 10:16 PM #150
Re: Liquid Overfeed Systems
corineramer,
How is your project developing? Are you guys done yet?
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