Refrigeration system design help?!

[Bash1803]

Hi guys , I wonder if you can help me?

Apologies if something similar to this exists already.

Myself and one of my colleagues are very interested in the design side of the business but have had no training in relation to design and no-one within our team to show us. We have set out on trying to carry out a basic design for a packaged refrigeration plant to chill brine for an ice rink (this is not a real project, just an interest point for us).

We have worked out the size of the plant we require, used pressure enthalpy diagrams to work out which refrigerant is best to use and worked out our refrigerant mass flow rate and dimension our system. Problem is, we now have no idea how to progress. Do you know where we could find a walk through or a set of instructions on how to proceed with our design.

I have been referenceing the ASHRAE refrigeration guide, but this only seems to give advice on good practice for systems rather than a design process. Any information or time you take to reply would be most appreciated.

Many thanks, Bash

[aramis]

This is old literature with the correct design procedures: Try googling “copeland refrigeration manuals system design” if you drop the “system design” you will (probably) get 5 manuals that may shed some light.

Buying books on system design may also help, but if you are asking this here I suppose this won’t be your preferred choice.

[Magoo]

Hi Bash.
I enyoy your enthusium to progress within the industry at your age of 21 . You will be hard pushed to find anything relevent to your enquiry.
Rather you should be applying equipement suppliers info to your application, theoretical stuff is fine but actual installed equipement is slighty different. Unless of course you want a purpose built system which can be horrenously expensive by comparison.
Added is the installation of your ghost system project, labour costs, electrical costs , compliance cost, engineering and overhead costs, contingency forcasts and warranty costs. Best to write up a spread sheet and add all and sundry. To get a feel for project, don't forget the profit margin not mark up.
Good luck
Do a cash flow projection that suits your cash flow and dictates a deposit with confirmed order from client and cover everything with a project insurance, another overhead cost, once suppliers deliver you own ii. You are getting 40 years experience from me, lost my shirt on a few, and made a fortune on most.

[mbc]

best thing look for other project as same as we are planing to do and use there knowledge with own experience .

fist thing in establish project is phys ably study and it different because of area , and markets and transportation
and labor cost and....

also marketing is very . very important and it is telling us what we should do and given us light where we should put our money.

refrigerant for chill brine for an ice rink is a NH3 and you can give your layout to refrigeration's company to get
idea how much it cost for you.

[Bash1803]

Guys,

Thank you very muach for all your replies, all very useful and interesting.

Aramis, I've searched out the manual as suggested, at a quick glance, looks fantastic, only trouble is that it's in Imperial units, best get the calculator out :)

Magoo, Thanks for this. Originally we are intending to make a totally bespoke system rather than a packaged type system. We are aware that the cost would be substantially higher, but were hoping to sacrifice high initial cost for an efficient, sustainable and durable design to maximise plant life and keep running and maintenance costs down.
However, your points have given us a lot of food for thought as there is clearly a lot of commercial aspects to this "project" that we hadn't considered. I think it would be fun if we compiled this as suggested as part of the project, could be interesting: then we can laught at the final sell price and only wish we could do it for real :)

MBC, thanks for your input, good point well made of the feasibility study.

We are looking mainly to see whether we can acheive a workable design on a technical level mainly. We are finding that this is such a broad area and it is hard to find any one source where all the required data is collated.
As I say, we know that we need a 2.5MW evaporator, a 3.2MW condenser and the compressor work done is 644kW. We got this from using the pressure enthalpy diagram, now we are trying to suss out how to pick our components and design the pipe work. Once we have done this (which is proving a task in itself!), we want to look at maximising efficiency through part load control, hopefully, utilising variable speed motors, and condenser pressure control to maximise efficiency.

Maybe we are dreaming as I am starting to believe we may well be expecting too much of ourselves, but hey, we are still going to give it a go. If nothing else, the whiteboard in our office looks impressive with all our algebra and sketches for when the boss comes in :)

[mbc]

hi bash
I think it should too expensive for you to go for variable speed motors in compressor motors (644 KW)

and it is better you go to choose 2 or 3 compressors to cover that loads and in market you can find very easy screw compressor in that capacity with 3000 RPM and unloading system and you can design your system in high load they work together and then in low load comes one off and other one if needs run in part unload system.
the supplier give more detail about that .
second side of brine evaporator design is important in ice rink system ( ice builder side) {salty water(brine) or glycol or calcium chloride circulation system }

[Josip]

Hi, Bash1803 :)


Guys,

Thank you very muach for all your replies, all very useful and interesting.

Aramis, I've searched out the manual as suggested, at a quick glance, looks fantastic, only trouble is that it's in Imperial units, best get the calculator out :)

Magoo, Thanks for this. .......

MBC, thanks for your input, good point well made of the feasibility study.

We are looking mainly to see whether we can acheive a workable design on a technical level mainly. We are finding that this is such a broad area and it is hard to find any one source where all the required data is collated.

As I say, we know that we need a 2.5MW evaporator, a 3.2MW condenser and the compressor work done is 644kW.

We got this from using the pressure enthalpy diagram, now we are trying to suss out how to pick our components and design the pipe work. .

Maybe we are dreaming ......

Can you, please, put some more light on bold section ... evaporator 2,5 MW ... condenser 3,2 MW and compressor cooling capacity 0,644 MW ... not sure, but maybe I miss something ... what is your idea ....

.... standard ice rink 30m x 60m ... Plate HE Rxxx/glycol (CaCl2 is too aggressive and you not need to go below -14*C ;)) ... with/without glycol buffer tank and glycol pumps ... how many compressors, it is possible to use VFD not so expensive with small drive motors, maybe rotatune SAB 128, SAB 163 .... evaporative or S&T condenser for heat reclaim ... etc ... some RE members can help more with some hints, but you must come out with your idea and we can comment it .... hope to be helpful to you ;)

And, please, do not stop to dream, ever .... usually we need some time til our dreams became true ...

Best regards, Josip :)

[mad fridgie]

Designing a system at peak load is the easy bit, you need to study your application (ice rink) and understand the influences which effect load at this area, and how you can control your secondary refrigerant temps and flows based around these influences.
From there you can determine the minimum load, which where most refrigeration design problems occur.
You need to consider, reaction times, load shifting, redundancy. Energy cost verses energy efficiency. load diversity.

[mbc]

HI bash
as I said before best idea to go head for you is a visiting other smiler project and see how they done.
also check your calculation again sound of size of your equipment is not right . please

[Magoo]

Hi Bash.
You have received a truck load of old experience and advise, donnot be daunted. But to sell a bespoke system /plant usually requires a massive engineering support basis. To be cruel a large corporation support system with a history of successes. A good start would be Coolpak to support any design concepts. As Josip said "keep the dream going ", break problems down to managable steps and work your way through them.
all the best. magoo