Document QMJOXYXyd2D9ZjeEw2YyzL125

608 CHAPTER 57 1962 Guide And Data Book inner lining. The furring acts as heat bridges and can in the container is always accessible and spare machines are crease the transmitted heat gain by as much as 35 percent available, replacement of the entire refrigerating mach}^ ^ over that of a homogeneous insnlat-inn more feasible. In marine service, the containers are subjected to frequent With efficiently insulated containers the movement of pre hogging stresses from fork-lift handling sagging stresses irom cooled or prefrozen produce between source and ship loading 4-comer hoisting at the ship, and tortiona! stresses in land may be classified as long-haul and short-haul operations. transport. While an effort is made to seal all joints of the con Short-haul may be defined as that in which the containers tainer shell, these stresses can quickly nullify the effort, and are loaded at the ship's ride, at nearby terminals or cold a permeable insulation is subject to heavy moisture gain storage plants, or at sources of moderate distance from the such as is experienced by the trucks. In truck service, sir infiltration through the insulation while under morion ha ship-loading berth. In such cases where the interval before resumption- of applied refrigeration is not extended, the been found to increase transmission heat loads by 10 to'27 attached refrigerating machine may be idled or absent. percent. Similar conditions should be anticipated for on-deck sea service. In long-haul operations some form of refrigeration must be provided, such as an attached refrigeration unit, dry-ice The ideal container would be one in which the boundaries, or, with frozen foods, by residual refrigeration through sub except the roof and floor, would be stiffened externally by cooling of tire product. metal shapes or corrugations. Internally mounted roof fram ing will not interfere with stacking, and the internal struc To meet these conditions three types of refrigerated con tainers have been developed or proposed. The first method ture in some cases is called upon to support hanging meat rails. utilizes the conventional arrangement of insulated con To clothe such internal structure additional thicknesses of tainer with an attached refrigerating machine, which may insulation are required. All framing should be of such scant ling that they will resist racking stresses under superimposed have two sources of power: (1) a butane internal-combustion engine for use on the highway, and (2) an alternating current loads of stacking, on-deck lashing, or tilting in a seaway. The motor which may be powered by the ship's electric plant external panelling must be of materials or coatings that will resist corrosion by salt air, sea spray, or trailing stack gaw*Tbe under-floor structure should be covered with automotive undercoating. Some schemes outfit the highway chassis with an electric, generator which supplies the single motor with current of the same characteristics of that of the ship. When t-H*^ - units are carried below deck, means must be provided to The insulation should be of such effectiveness that it can remove the rejected heat from the ship's compartment. This economically provide sub-zero temperatures in 100 F am has been accomplished by outfitting each machine with an bient. The ideal assembly will call for polyurethane resin air-cooled condenser for highway service and a water-cooled foams poured in place between shell and lining and without condenser for service on the ship. While in the ship, the benefit of furring. The insulation should be applied with water-cooled condenser is connected by hoses through which bonded joints between successive pours, as it will chafe under fresh water is succesively recirculated through condensers frictional movement. These foams have sufficient strength and heat exchangers. An alternate arrangement for a characteristics for the service and their high bond to the purging mechanical ventilation system. The refrigerating forms lends strength to the overall assembly. Properly ap machine is similar to the standard highway unit but is es plied, they will provide adequate moisture-vapor resistance. pecially fitted to resist the severe and corrosive conditions Internal linings of walls and overhead may be of ply- of sea service. The power demand of these units is high board, wood fiber hardboard, glass fiber sheet, or plastic With large shipments of cargo, the supervision main laminates. The walls must be fitted with the equivalent of tenance of multiple machinery becomes a matter of opera cargo battens to insure air circulation between the cargo and tional concern. the linings. The floor may be of square metal corrugations or ' A second method of transporting frozen foods has been extruded aluminum shapes to permit circulation of air under projected in which the product is deeply subcooled by liquid the cargo and to support all service loads during loading or nitrogen after loading into the container. The degree of sub- discharge. cooling varies with the length of voyage and is intended to There are fundamental differences in the bases which govern allow transmitted heat gain, delivering the product at a safe the design and operations of the marine refrigerated cargo temperature level. container from those which guide the design and operations The third method being developed places the loaded con of the ship's built-in cold storage plant. While the ship's plant tainer, without refrigerating nmehine in the ship's insulated is not called upon to freeze cargo, it covers all other refrigera compartment in the same manner as the traditional built*in tion demands including the arbitrary 72 hr (equivalent) pull plant having remote and centrally controlled refrigerating down load of unprecooled fresh produce. Furthermore, the machinery. The container is fitted with closeable low inlet ship's plant traditionally is designed with spare refrigerating openings at the door end, through which ambient sir is machinery and ample margins of heat removal capacity. The drawn by an exhaust fan located high in the front end of the possibility of failure in performance is extremely remote. container. The fan discharges the air back into the ambient It is the generally accepted concept that the sea-going space. The method has been designated as an ambient re . refrigerated container has inherited from the highway services frigeration system. It is intended that, for short-haul service, / the condition that the container is designed to carry only no attached refrigerating machine is required. For long-haul precooled or prefrozen cargo received at carrying tempera service, the portable attached refrigerating machine is sub tures, and that maximum capacities of the attached refrig stituted at the ship's side with an insulated aperture panel erating machinery may nearly match antieipat^d maximum upon which the exhaust fan is mounted. The fans are con heat removal loads. There are no spare machines and the nected to the ship's electric system by portable cords with . only safeguards against failure and malfunctioning of an remote gang circuit control. attached machine are the spare parts carried by the vessel The roll-on-roll-off method of sea transport in commercial and the alert supervision of crew members. On shore, where trade is economically suited to short voyage services. Trans- Marine and Air Transport 609 ^ by this method involves the use of highway trucks and LTyerg, complete with their running gear, and is not an efficient use of a ship's compartments. In military service jo not a prime factor. Refrigerated trucks and trailers discussed in Chapter 55. PART il: SHIP'S REFRIGERATED STORES Today, most vessels are equipped to carry provirions for . voyagts without provisioning en route. The refrigerating eooipment must operate under extreme ambient conditions, jbere is increasing use of frozen foods. Modern mechanical refrigeration and food technology make possible food pre- remng conditions for long periods for perishable stores at sea. Hence, the trend is toward lower temperatures with in creased attention given to other factors such as packaging, tumidity, and air circulation, and the increase of space re- marements in modern marine installations. Perishable foods go aboard fresh, dehydrated, canned, smoked, salted and frozen. For some of these, refrigeration is an absolute necessity; for others it is advisable but may be omitted if the storage period is not too long. Space is costly &boaid *hip And is always limited. Therefore, many rooms at different, temperatures cannot be practically provided- The befits of modem food technology can be obtained for all practical purposes by providing conditions outlined in Table 2 and as described below. ^ Commodities Meats and poultry. Substantial savings in space, labor of preparation, und better quality can now be obtained by mak ing use of pre-cut, boned, frozen meat and poultry packed in moisture-vapor-proof cartons and wrappers. For this reason, increased 0 F storage space should be anticipated. Fresh meats are less suitable because of their relatively short storage life. The space required for fresh meats will be from two to four tinwq that needed for prepackaged meats. Fish. Frozen fish is now readily available. Good quality fish properly prepared and packaged, will remain odorless and palatable for long periods of time. lee cream. Commercially prepared ice cream is nearly al ways available and used to a great extent for both passenger and freight vessels. Ice cream for immediate service should be kept at a slightly higher temperature in an ice cream cabinet in the galley or pantry. Ice cream making equipment may be desired, in which case provision must be made for hftjHonjng the mArhine-made ice cream, ices, and sherbets. Bread. Excellent results can be obtained by purchasing bread freshly baked, sealed in moisture-proof wrappers, and stored at 0 F. This supply may be supplemented by bread and other bakery items made on the ship. Frozen bread may be thawed in its wrapper in a few hours. Frozen fruits and vegetables. Packaged frozen fruits, fruit juices or concentrates, and vegetables may be stored in any freezer room. All of the packaged frozen products mentioned may be held in a common 0 F storage space. However, the increased usage, especially on large passenger vessels, may justify separate refrigerated spaces for some or all of the products. Fresh fruits and vegetables. There are some products not suitable for freezing or in some cases the fresh grown product is desired. These items may be stored in a common room, but some compromises with their optimum storage conditions must be expected. Growing use of frozen products is reducing the demand for fresh fruits and vegetables. Dairy products. All dairy products may be stored in a single room, following customary shore-ride practice. Strong cheeses with odors that might be adsorbed by other foods should be stored in a tightly enclosed chest or cabinet placed in the dairy refrigerator. Eggs may be processed by oil dipping or heat stabilization to them less sensitive to unfavorable humidity conditions or odors. Large passenger vessels should be fitted with a separate egg storage room. Butter for reserve supply should come aboard frozen and be kept in a freezer. Frozen homogenized milk has been perfected to a degree that it can be carried for reasonably long periods. Asepticaily whole milk is now available tmd may be stored without benefit of refrigeration, but this product has some limitations because of the faintly detectable cooked flavor. Ice. The making of block ice on any marine installation is of questionable practice because of operating.difficulties as- Table 2 .... Classifications for Ships' Refrigeration Services Service rop, r For Per center Vsel* For Freight Vtath . Freezer Rooms Meat*--poultry Frozen foods Ice cream Fish Ice Bread QXX 0XX 0XX 0XX 28 X ' 0X Chill Rooms Fresh fruit--vegetables. Dairy products--eggs Thaw rooms Wine rooms Bon voyage packages 34 32 40-45 48 40 X X X X X X X X Service Boxes Main galley Cooks' boxes Butchers' boxes Bakers' boxes Salad pantry refrig. Coffee pantry refrig. Ice cream cabinet Ice chest Mess Rooms or Pantries Deck pantries Wine stewards' box Bars--fountains 40 X 40 X 40 X 40 X 40 X 10 X See text 40 40 40 Various 'X X X X X X Miscellaneous Ice cube freezers Ice cream freezer Biologicals Drinking water systems Canned foods Dehydrated foods See text See text 40 See text See text See text X X X X X X X X Ventilated Stores Hardy root vegetables flour cereals See text X See text : X X X