Ice Rink Ammonia Refrigeration Plant

[Makinice]

Hello all,
I'm new to the forum as well as Ammonia refrigeration. We have an Ammonia refrigeration plant that makes ice for hockey. In the original design of the buiilding, the engineers put this plant on a common condenser header with the building cooling chillers. I have found that I can run our small chiller much more efficiently with 55 degree tower water in the early spring, late fall and winter, but what I don't know is if our ammonia plant condenser will like the 55 degree water. I understand the concern is stacking of liquid ammonia due to insufficient temperature/pressure differential. My question is... Is there a calculation I can perform to find out if the 55 degree water will work for this plant? The manufacturer has been less than helpful in providing this information, and I've scoured the internet to no avail.

Thank you in advance.

[Josip]

Hi, Makinice

welcome to RE forums ...

Hello all,
I'm new to the forum as well as Ammonia refrigeration. We have an Ammonia refrigeration plant that makes ice for hockey. In the original design of the buiilding, the engineers put this plant on a common condenser header with the building cooling chillers. I have found that I can run our small chiller much more efficiently with 55 degree tower water in the early spring, late fall and winter, but what I don't know is if our ammonia plant condenser will like the 55 degree water. I understand the concern is stacking of liquid ammonia due to insufficient temperature/pressure differential. My question is... Is there a calculation I can perform to find out if the 55 degree water will work for this plant? The manufacturer has been less than helpful in providing this information, and I've scoured the internet to no avail.

Thank you in advance.

To get a correct answer you need to give us as much as possible data .... anyhow ...

what degree F or C ... assume F what is about 12,7oC ...

your ammonia condenser will be very happy and your bill for electrical power will be lower ... the best will be to maintain your condensing pressure/temp about 11 bar i.e. 30oC or 86-90oF ... we do not know what system you have to control condensing pressure ...

don't worry, that difference in pressure is enough to feed your suction drum ... assume your evaporating temp/pressure is at least -7oC/19,4oF i.e. 2.28 bar for skating and for hockey you must go down to -15oC/5oF i.e. 1,36 bar or even lower ...

Hope this will be of some help to you ....

Best regards, Josip

[Makinice]

Hi, Makinice

welcome to RE forums ...




To get a correct answer you need to give us as much as possible data .... anyhow ...

what degree F or C ... assume F what is about 12,7oC ...

your ammonia condenser will be very happy and your bill for electrical power will be lower ... the best will be to maintain your condensing pressure/temp about 11 bar i.e. 30oC or 86-90oF ... we do not know what system you have to control condensing pressure ...

don't worry, that difference in pressure is enough to feed your suction drum ... assume your evaporating temp/pressure is at least -7oC/19,4oF i.e. 2.28 bar for skating and for hockey you must go down to -15oC/5oF i.e. 1,36 bar or even lower ...

Hope this will be of some help to you ....

Best regards, Josip

Thank you Josip. This does help quite a bit! I'm sorry I didn't specify the unit of measure. I was speaking of Farenheit. Our ammonia suction pressure normally runs anywhere from 10-30 psi, and our discharge runs at 125-150 psi, dependant on the load. This is with 70oF condenser water. The package has Direct Digital Controls that modulate a Danfoss metering valve. It has 3 compressors that cycle on and off depending on load, so I would like to run the least number of compressors and save energy. My hope is that the lower condenser water temperature will allow better heat transfer so we can stay on one or two compressors and never need to run three.

Thank you again for your response.

[Josip]

Hi, Makinice

Thank you Josip. This does help quite a bit! I'm sorry I didn't specify the unit of measure. I was speaking of Farenheit. Our ammonia suction pressure normally runs anywhere from 10-30 psi, and our discharge runs at 125-150 psi, dependant on the load. This is with 70oF condenser water. The package has Direct Digital Controls that modulate a Danfoss metering valve. It has 3 compressors that cycle on and off depending on load, so I would like to run the least number of compressors and save energy. My hope is that the lower condenser water temperature will allow better heat transfer so we can stay on one or two compressors and never need to run three.

Thank you again for your response.

If you have enough load to run all three compressors for some short time until load falls that is inevitable, but you can save a lot of energy if you have available "free" cold water to reduce condensing pressure as much as possible ... you can see your plant is running fine even with condensing pressure of 120 psi i.e. 8,3 bar ... if you can provide that all the time then after one month you'll see how much energy you save ...

maybe you can switch off one compressor and check behavior of your ice i.e. temperature and hardness good for hockey .... two compressors should run longer at higher capacity, but if your ice is OK you can cycle compressors every day manually .... it is a kind of game ...

try to find out what is your maximum evaporating temperature/pressure till you have a good ice and if you can obtain that with only two compressors running .... at least in spring, autumn and winter time ... long time to make some good savings

My suggestion is to make improvements in very small steps ... don't try to improve all at once, no way, believe me.

Hope this is of some help to you.

Best regards, Josip