GEA Grenco is a contracting company in the Netherlands. One of the important market segments of GEA Grenco is the installation of refrigeration plants on board of large fishing trawlers. At GEA Grenco CO2 is considered to be an excellent refrigerant for freezing fish in vertical plate freezers, because of the following advantages: (1) In comparison with ammonia CO2 is less toxic and is therefore allowed by shipping authorities to be used as a refrigerant for direct cooling of plate freezers, whereas the use of ammonia is only allowed in dedicated engine rooms. (2) In comparison with HFC refrigerants, CO2 has a minimal global warming potential. (3) In comparison to secondary refrigerants as glycol and calcium chloride brine, CO2 has a superior heat transfer. Before installing a CO2 refrigeration system on board of a fishing trawler, GEA Grenco considered it necessary to build a small CO2 plate freezer test plant. The test plant was used to gather experience about the following subjects: (1) Freezing speed, (2) influence of lubrication oil on heat transfer, and (3) optimum defrost method. A number of freezing tests and comparing the results with data of an alternative cooling media as refrigerant, R404A and secondary refrigerant calcium chloride brine show that the superior heat transfer of CO2 can be used to save energy while maintaining the same freezing speed. The results of the calculations are listed as follows: (1) Savings in comparison with NH3/CaCl2 brine: 15 % (including pumps) and (2) savings in comparison with R404A/R507: 20 %. On board of fishing trawlers CO2 is used in a NH3/CO2 cascade refrigerant plant. In a cascade plant the CO2 compressor will carry over oil to the refrigeration plant. From the tests it can be concluded that the presence of lubrication oil has a limited negative effect on the heat transfer. CO2 defrosting is done by a special CO2 screw compressor unit capable of operating with a discharge pressure of 45 bar. This pressure is high enough to use this compressor directly for hot gas defrost. The comparison of energy consumption of different types of freezing systems show that for all conditions the NH3/CO2 cascade installation has the lowest energy consumption. Technical data of the refrigeration plant are given for the fishing trawler Ocean VII and Dirk Dirk.


    Access

    Access via TIB

    Check availability in my library

    Order at Subito €


    Export, share and cite



    Title :

    CO2 as refrigerant on board of large fishing trawlers


    Additional title:

    Kohlendioxid als Kältemittel auf großen Fischereischiffen


    Contributors:


    Publication date :

    2005


    Size :

    6 Seiten, 11 Bilder, 1 Quelle



    Type of media :

    Conference paper


    Type of material :

    Print


    Language :

    English




    New deep-sea fishing trawlers

    Engineering Index Backfile | 1938


    New deep-sea fishing trawlers

    Engineering Index Backfile | 1938


    Two more converted fishing trawlers

    Engineering Index Backfile | 1933


    Two more converted fishing trawlers

    Engineering Index Backfile | 1933


    Large trawlers

    Jaeger, H.E. | Engineering Index Backfile | 1954