heat exchanger

[knighty]

hi

long story short, I own a small frozen dog food factory, and with the hot weather coming back again freezing everything we need to freeze is becoming a problem (up to 4,000lb of meat needs to freeze overnight)

I'd like to help the condensers out a bit by cooling the hot liquid just before it enters the freezer room with cold water....

does anyone know where I can buy a heat exchanger to do this ?

I *think* the tubing is 15mil going in and 22mil coming out thanks

Alan.

[Brian_UK]

Hi Knighty, welcome back, how's the leg?

Before we start remodelling you system again, did you get it up and running as you wanted last year?

A quick fix right now would be to run a water hose with a spray head and point it at the condenser coils; don't spray at full force a gentle spray will suffice.

[not tamed]

Hi Knighty, welcome back, how's the leg?

Before we start remodelling you system again, did you get it up and running as you wanted last year?

A quick fix right now would be to run a water hose with a spray head and point it at the condenser coils; don't spray at full force a gentle spray will suffice.

leave it to the pros what you are conserding doing is just nonsence

[slingblade]

does anyone know where I can buy a heat exchanger to do this ?

Yes.

I *think* the tubing is 15mil going in and 22mil coming out thanks

Take it from me, it is not 15 and 22 mm.

leave it to the pros what you are conserding doing is just nonsence

Agreed.

[Brian_UK]

leave it to the pros what you are conserding doing is just nonsence

Hi not tamed and welcome to the forum, a little bit of history about yourself as way of introduction would be of interest to us all.

[Peter_1]

Not tamed, - what a name - seems your just in the business and missing some, no.. a lot of experience.
Done this hundred times, even today, 3 times with a very good result.

[Temprite]

A quick fix right now would be to run a water hose with a spray head and point it at the condenser coils; don't spray at full force a gentle spray will suffice.

Brian did only say a quick fix......

Not a long term solution.

I worked on a supermarket where the owner hooked up a sprinkler to every unit. When the weather got over 30 deg C he would turn on this system.

The gear serving the supermarket was in pretty poor condition(Probably due to water being sprayed on it).But without doing this on some hot days it would stop running.

BTW I am not recommending this practice.

[Brian_UK]

I don't recommend it long term but sometimes it's all you can do with the kit that has been installed.

Some customers will just NOT spend the money or, also relevant, they cannot afford the upgrade yet.

[old gas bottle]

the units obviously flat out,jet wash the condenser,[remove the fan assy first] thats your starting point !, is there a siting problem with venilation !, maybe look to getting hold of a remote condenser as a cheaper solution.

[knighty]

Hi Knighty, welcome back, how's the leg?
Before we start remodelling you system again, did you get it up and running as you wanted last year?
A quick fix right now would be to run a water hose with a spray head and point it at the condenser coils; don't spray at full force a gentle spray will suffice.

wow you must have a good memory !

my leg's much better now thanks, I'm pretty much back to normal

last year... I ended up buying an extra freezer room so I can leave stock flat packed on trays for longer before its packed into boxes.. it was a temporary fix and I was hoping to have something more permanent by now.... things are so busy at the moment that if it doesn't absolutely have to be done right away, then its not

I've steam cleaned through the condenser coils already and air flow is good, I thought about having a small spray of water over the condensor.... but I'm worried about the problems caused by the water (corrosion etc..)

[knighty]

and now for an update... after a check today, the freezer was still struggling to keep the temp down and get everything frozen... the high pressure (liquid) line coming out of the compressor was very hot, too hot to touch, but by the time the liquid was re-entering the fridge it was pretty well cooled down, so I'm thinking the water cooling might not be enough, and I'd rather go for a longer term system. (spreading products out around numerous freezers is a pain and time taking)

but.... I do have a couple of spare hardly used full system's that I picked up cheap when a local factory closed down... If I find the spec. of those compressors, and for the compressor I'm using for my main fridge would you guys be able to point me to an expansion valve and pro. heat exchanger to link the 2 up ? (having the smaller compressor cooling the liquid before it enters the fridge) ?

I'm friends with a local refrigeration engineer who could hook it all up for me, and I could wire it in myself no problems

[knighty]

p.s. the cheaper the better

edit:

the main freezer is running on 404a (I'll double check that tho)

what kind of temp can I go down to with 404a without any problems ? (oil freezing etc..)

I don't really need to be any colder, just need to keep the temp down and to bring it down quicker... the freezer normally runs at -18'C but I've set it to -23'C at the moment (as low as it will go)

I'm not sure if it will ever make it down to -23, but every degree helps in with this weather !

[The MG Pony]

What I would sujest is switching to a better gas then over sizing your condencer system a bit, that will assist in sub cooling and lower the head pressures and temps, providing there is a beter suited replacment, but in either case putting in a larger Condenser will help I do think.

[knighty]

mm, can you point me to a better gas ?

I've searched these forums, but theres so much information, and a lot of it is gobildygook to me

the idea behind the heat exchanger is, I could add a lot of cooling capacity to the system for relativly little money... (with water all i need is the heat exchanger and pump, using a second compressor all i need is the heat exchanger and a expansion valve for it)

thanks

Alan.

[The MG Pony]

Hmmm Could get a 20 plat heat exchanger low profile and high performance.

Find a gas with the same low temp but with lower head pressures.

[US Iceman]

the high pressure (liquid) line coming out of the compressor was very hot, too hot to touch...

The hot line coming out of the compressor is the discharge gas line, not the liquid line. The liquid line is the pipe that comes out of the condenser.

If you want to pick up a lot of cooling capacity, install a small brazed plate heat exchanger (BPHE) in the liquid line (downstream of the receiver). Use a little refrigeration system to cool the BPHE. Now you have an instant mechanical subcooler.

Of course it all has to be sized correctly to operate properly.

Changing the gas is too much like playing around with the system until you get a favorable result. I would not recommend this.

This subcooling system should start when the main refrigeration system starts, and shut off when the main refrigeration system stops.

[chistine]

good idea,

[Renato RR]

Ad air cooled condenser in parallel with old one.Fit the solenoid valve on new condenser inlet.Dgust you need to fit the right size condenser.

Renato

[Samarjit Sen]

I fully agree with US Iceman. He has given a very effective solution, but you have to do the proper selection of the subcooling system. Even Brians idea of spraying a small amount of water over the condenser is good, but should be done for a short while till you adopt Icemans views. Why not try for a day and see the changes it brings. I have done it a number of times and the results were good. However finally you have to change your condenser to match the total heat rejection of the compressor. Both the ideas are good.

Samarjit Sen

[chistine]

does anyone know where I can buy a heat exchanger to do this ?

I *think* the tubing is 15mil going in and 22mil coming out thanks

Alan.[/quote]

You know, it is not just providing equipments, also a cooling solution, you can contact me

[Peter_1]

What I would sujest is switching to a better gas then over sizing your condencer system a bit, that will assist in sub cooling and lower the head pressures and temps, providing there is a beter suited replacment, but in either case putting in a larger Condenser will help I do think.

Changing to a gas with a much lower HP will give you a lot less cooling capacity.
This isn't the proper way to solve this.
There's basically something wrong and this must be changed/improved.

[Samarjit Sen]

Changing refrigerant would reduce the capacity as has been rightly said by Peter 1. Some years ago I had read in a Searle catalogue, that by installing a heat exchanger of the type suction/ liquid in the discharge pipe line before the condenser, and passing water through it so as to cool the discharge line, one can attain a much better condensation. I had done the same on a couple of plants and had found these to be very effective. Maybe you can try the same.

[knighty]

well... as a temporary meausure I added the most powerfull fan ever imagined hanghing infront of the condensor.. sounds like a jet engine and I can't run it during the day because its too noisy..... just waiting for the electric bill now

but... I'm in the middle of sourcing a heat exchanger I can run water through to use as a more permenant solution.... which should be cheaper than runing 2 units :-)

spending about £200 a week on electric as it is (about $370)

[US Iceman]

knighty,

You are spending a lot of money for questionable results.

spending about £200 a week

If you can afford several months of this additional cost, you can afford to pay a good refrigeration person to fix your problems.

Several months of this expenditure would probably pay for the separate subcooling system. Then you can concentrate on the condenser problem, maybe?

[knighty]

sorry, I should have said, that;s the total electric bill for the company, not just the extra fan !

tho most of that bill will be for the fridges/freezers... the rest will just be for lights, we have a few big machines but they don;t run for that long.

[cascade tech]

Hi
Heres the bush mechanic method of head pressure control for air cooled condensors.

Equipment needed:
1.) Automatic garden sprayers, associated piping, fittings and water solenoid valve.
2.) Automatic reset discharge pressure switch or suitable thermostat to monitor liquid line temprature.

Method :
1.)Mount the sprayers under the condensor, i hope the fan motors are waterproof.
2.)Use the pressure switch to switch the sprayers on when the head pressure gets to high and off when it gets too low.
Or use the thermostat to monitor the liquid line temprature.

This is not the way to do it, rather get a condensor thats properly sized for your maximum ambient conditions.

Hope you get it right.

[refteach]

Be careful about spraying water on condenser coils, depending on the hardness of the water you would not only have corrosion, but also calcium build up and it may end up lowering the efficiency of the coils in the long run. You are essentially making an evaporative condenser, but when you start to evaporate the water the residual minerals and salts that are present in the water are left behind. In evaporative condensers the water is recycled and it is monitered and treated to prevent the accumulation of mineral deposits and salts that are present in the water.