Marine Refrigeration

[suny]

Hi Guys

I am interested in fabricating a Blast Freezer & a Storage Cold Room temperature of -22 deg C for a fishing trawler. If u have any experience in this field pls share with me.

Best Regards
suny

[Samarjit Sen]

Good Morning Suny,

Although I do not have any practical experience on marine applications, but yes I had done some design work on the same.

Could you please let me know as to what is the capacity of the Blast Freezer and the Cold Storage Rooms.

[lana]

Hi suny and welcome.

For transport refrigeration you have to use special compressors which are known as "transport refrigeration compressors".
If you use ordinary compressor then it will fail on oil problems.
Regarding the cold room and the blast freezer, the design procedures are the same as normal rooms on the ground. On the ships however the major concern is the defrost. The air is moist and on the other hand the fish is completely wet when put in the rooms.

Cheers

[smpsmp45]

For Water cooled condesners you need to provide Liquid ref outlets at both the ends of the Condenser shell. This is to take care of pitching / rocking of the boats. Our normal condesners have outlets only at one side.

The freezer capacities are very small. I have seen No of Japanese equipments on such applications.

[Eeram]

Hi Suny

Marine Refrigeration is very similar to land applications, the only difference is that the units must be very compact due to space restrictions.

Normal semi hermetic compressors can be used, however make sure they have deep oil sumps. Bitzer and Copeland make provision for that. Mount the compressors parallel to the drive shaft of the main engine of the vessel, with the compresser sump facing the stern. Single outlet receivers are usually mounted with their liquid outlets towards the stern side, because when the vessel is loaded, the stern are deeper in the water.

Make sure every refrigerant line is securely clamped because rough sea conditions can break anything.

Evaporator coils are normally specially made with copper fins and has more reinforcing than standard stuff.

Hot gas defrost are used on vessels because they are most effective and they are normally manual start with automatic termination after 15 minutes or so.

The most popular in our region nowadays is plate freezers from Gunthela enterprices from Canada.

The best refrigerant to use is R-507.

If you need more information, send me a PM with your email address.

Eeram

[Samarjit Sen]

Hi Suny,

Eeram has given you the correct system design. For Condensers, there arespecial condensers available which are known as Marine Condensers and the best to get is the Standard refrigeration, USA or Bitzer.

Generally the compressors which are being used in our country for fishing trawlers are Open Type Reciprocating Type. You can use Bock or Bitzer. This is because in the fishing trawlers the refrigeration system is being generally operated by a seperate generator or an engine whose shaft is directly V belt driven to the Compressor.

[Samarjit Sen]

Hello Eeram,

It would be very much appreciated if you submit the details on the Forum, so that we the other members who are also interested to know may be aware of the details. That is why this Forum is very much liked.

[suny]

Thank you very much providing smoe tips. I will be touch with you for insulated pannels for the blast freezer
Best rgeards
suny

[Eeram]

Hi Samarjit Sen

I am happy to share with everybody, but I am still to stupid to add files, pictures or drawings to the forums. Can anybody help?

We have successfully equipped Tuna Boats with DWM Copeland 2 Stage compressors running on R-507 in a multiplex configuration. (6 X 25hp Compressors in 2 multplex systems) Multiplex refers to 2 or more compressors running in parallel.

The Tuna Boat runs at -67 Degree Celcius in the holds and Blast freezers! With temperatures so low, oil with a freezing capacity of below -85 degree Celsius must be used.

[Samarjit Sen]

Hi Eeram,

It would be nice if you can at least provide us with the system designs. I myself am not aware of how to or wether it is possible to upload the drawings. For this I am sure one of the moderators would be able to help.

From the details provided by you, it appears that the trawler must have been pretty big. General in the Southern part of our country and along the sea coast, the fishing trawlers are small in size. They use separate engines to drive the compressors either by V belt or direct drive system.

[lana]

Hi Eeram,

You can attach your drawing. BUT I think there is post count for that. You have to have 15 posts so you can attach a file. (I think:confused:).

Try once. Click the button under the screen which you type the post named "Manage Attachments". And then attach your file. There is a 100KB file limit.

Cheers

[Eeram]

Hi Samarjit Sen

The fishing vessels that we worked on in South Africa range from 45' to 90' in length.

54 footers normally has 2 Blast freezers that can pulldown squid from about 19 degrees Celsius to -30 in about 12 Hours. The blast freezers takes 1000 kg a time.

The hold normally takes about 10000 kg of squid at -25 degrees celsius and is about 5 X 6 X 2.4m high.

Thera are 3 X 20 Hp DWM Copeland semi hermetic compressors, one for each system, running from generator sets on the vessel.

Evaporator coils are purpose build with copper fins and condensers are shell and tube for marine applications (can handle seawater)

Controls are standard and we stay with the normal mechanical stuff, pumpdown with hot gas defrost.

The only difference from land applications is the fact that everything is build very compact due to space (you sometimes need small technicians!) and everything must be secured properly because the sea can be rough at times.

Cooling load calculations are the same for land base equipment.

In some of the older vessels, open drive compressors were used, working from the main engine.

Newer vessels are using semihermetic screw compressors or 2 stage compressors for extra low temperatures.

Regards

[Eeram]

Hi lana

Unfortunately a 100kb is not much to send technical stuff. I do not want to jump the forums, but everybody is welcome to send an email for information.

Just remember that I am a normal guy with normal working hours and only have evenings and weekends to spare! So please be patient.

regards

[The MG Pony]

look up http://www.pacificwestrefrigeration.com/ and talk to them about design, they are a strong company in the field.

[Samarjit Sen]

Hi Suny,

What is the progress of your Blast Freezers and Cold Storages for the Fishing Trawlers. The Blast Freezers shall be at a temperature of - 40 Deg. C Te and the Cold Storage shall be at -30 Deg. C Te.

I would suggest that you go in for a double stage Compressor using R 22. What I understand from the Bitzer personal that the space is a constraint for you and there is no place to have two compressors. Otherwise I would have advised you to go in for the Cascade system.

[TXiceman]

Other than being more compact, you also have to make arrangements and consider the liquid sloshing in the vessels from roll and pitch. The vessels will require baffles and or over sized to allow for the sloshing. This can be especially in suction drums, flooded evaporators and compressor oil sumps.

Another requirement is any local marine codes. In the US, the ships and equipment have to be approved by the Coast Guard and the ABS (American Bureau of Shipping). Other countries have similar requirements. They often require the design to be review and approved by a licensed professional engineer.

Ken

[Samarjit Sen]

The main thing to be particular in marine refrigeration is that the oil sump of the compressor has to be extra large.
The refrigeration system shall remain the same as it is for stationary application.

Fishing trawlers has to have a blast freezers with high quality evaporators with excess surface area for suffecient air velocity and air volume and should be located such so that the air supply and flow is over all the products. The cold Room for storage shall be with low air volume and velocity just to maintain the temperature.

[Samarjit Sen]

This is an old thread. I would like to know a bit about the space that are generally available below the deck for installing a Cold Room for a Fishing Trawler. In case any body can provide a sketch or a drawing, it would be of help.

I know that all fishing trawlers will not be similar, but it is just a general idea that I am looking for.

Thank you.

[lloydjosang]

The company I work for has built many of these type of freezers for many years. Please PM me your particulars and I will see what our engineering staff has to say.

[australian tech]

having worked on many a prawn trawler in warm waters of darwin(australia) a trusty compressor i would recommend is the G.E.A. GRASSO RC69 (2 stage r22 ) or even the newer models (series 10) they are not the most compact units , but they are very service friendly and bloody tough.

[Samarjit Sen]

What about the Evaporator ? Would you suggest a coating over the coil fins and tubes for the prawn. What about the Humidity.