Sizing Condenser to Evaporators for different Applications

[Peter_1]

Proper operation of the Blast Freezer is ALL that is needed to Save Energy in the Application for which it is to be utilised. Peter

This is not ALL what is needed to save energy. It's a wrong statement. It starts and depends almost solely with a proper design.

You can have more BTU's if you lower the HP (and even rise the LP), so a lower DT over the condenser and also designed that way. Because once designed and installed, you can't change it afterwards.

The air circulation doesn't say anything: the design of the whole concept, especially the room itselves is much more important.

You need a condensing unit who can give at 95,000 BTU at the desired evaporating and condensing pressures. That's all.
If the 95,00 is correct of course.
I'm not familiar wit IP units but did a conversion from your 95.000 BTU to tons which gave me completely different figures.
You need something around a 30 Hp unit, given that 95,000 is correct.

Do you need capacity control, partial load, is room stacked always full, is it a FIFO freezer, ....

DT: if outside conditions are 35°C then you're compressor must be able to condense at max 45°C or ....psi (you didn't gave the gas you will use)

Without having the intention to be rude....designing a blast-freezer is not that easy as it looks on the first sight.
I strongly recommend that you try to find someone experienced to figure out, eventually together with you what your client needs.

[PHENERGY]

Well, you did initially state that my outlook is gonna differ because I an an energy consultant, the fact of the matter is that the system that the blast Freezer is to REPLACE uses quite alot more energy. The Gas Iwill Use is R-404A. I do not use a blast Freezer simply to blast freeze but as part of a totally different concept, so from my perspective ALL I have to do is to get a proper operation at
-30 F and the minimum air circulation and presto I will have saved lots of energy ( will post results after completion of this design) the fact of the matter too is that I am in consultation with a Very experienced Contractor but I like to cross reference and have an idea of things before he makes his recomendations he is to give me his design tomorrow. For a previous blast freezer he designed and used two 15 HP condensing Units, but I did not know the evap size, this time arround I know the Evap size, so I guess he may design at or arround 30 HP as you have suggested.

Peter

[TXiceman]

Peter_1 is right. It is not hard to balance a unit cooler with a condensing unit. You simply plot the unit cooler at a couple of capacities and TD's (temperature diferences) and then cross plot the condensing unit against the unit cooler. Where ther cross is the balance point with no line losses. You need to offset the unit cooler by 2 dF to allow for suciton losses and that is you actual real world balance.

Also, designing a blast freezer is not all that hard, but does require some knowledge of air flow and product spacing/packing. Does your Larkin unit cooler have cast air foril fans or are they the stamped flat sheet metal baldes? You generally want to rate a unit cooler fan for 1/2" W.C. (water column) static pressure (SP) because you will have some static loss in a blast cell getting the air through and around. A flat sheet metal blade can not produce the static pressure and will not produce sufficient CFM (air flow).

If you want to balance a separate condenser with a compressor and them a unit cooler, you have a whole new ball game. It ican be balanced by hand, but takes a bit more work. Both of these are something that I do on a daily basis, bit not something to expalin over the net. If you post some model numbers, I can see if I have the literature on the equipment and could do a balance. If it is used equipment andyou are changing refrigerants, you need to watch out on the unit cooler. The distributor and nozzle may not work for te new application.

Sounds as though you need to hire a refrigeration engineer to keep you out of trouble.

Ken

[PHENERGY]

Hey Thanks a lot Txiceman for offering to help, Peter_1 too.

The Larkin Evaporator model # is ELT611704, the name plate says it is designed for use with R-12 or R-22 or R-502. but I will be using R-404A gas.
The fan blades are riveted to a central metal plate with a detachable 5/8 hub with Allen nuts to tighten onto the motor shaft, 27 degree pitch. the blades are curved inward.

There is a lesson for me to learn in all this. In the past I have used an experienced Refrigeration Contractor who has always delivered, he does not supply equipment but designs and installs and commissions. But this time around the refrigeration equipment supplier is new to me and he insisted that to maintain his warranties he would have to install and commission his systems, thereby forcing out my regular guy, and therein was the start of all these problems, basic errors has been made, the Texaco Capella oil instead of the POE with the R-404A a few weeks ago for example. Now he is offering a condenser driven by a coplamatic Compressor Model # 3DF3-090E-TFC-800 to work with the Larkin evap and I just do not believe it is properly matched to deliver a blast freezer, at the conditions previously stated in this thread
I have since contacted my regular contractor and he will pay a site Visit today and see what can be done but I am always grateful for other opinions. I anxiously await your replies.

It will be very difficult for any one to separate me from my regular guy in the future.

Peter

[Capt Steve]

Hello PHENERGY,
The best source for you to size that equipment, is typically the supplier of the evaporator and condenser. Larkin, is now owned by Heatcraft, and they have engineering that will help you size that specific evap coil to the needed condensing unit, with the energy efficienct condenser.
Just a thought.

Capt Steve

[TXiceman]

I'll look in my library tomorrow and see if I can identify the models. Are ou running 50 or 60 HZ power?

ANd Capt'n, if he can get a factory Lain engineer,he can get some help. A lot of the local reps would be stretched to make a proper equipment balance.

Ken

[Peter_1]

Isthis the one you're looking for?