Comparison of bare and finned pipe coils in frozen fish storages

Abstract

One can successfully use forced air cooling units for short term bulk storage or in stores where products are processed and packed in special materials in order to reduce moisture losses, eg retail packets or consumer packages. Bare pipe evaporators are well suited to cold stores where the aim is to maintain a fairly flexible loading pattern in small or average size installations, in which the product weight on roof structures and the refrigerant charge are not critical factors. These evaporators are also suitable for stores in which one or more rooms are almost empty during certain seasons, such that thawing is facilitated. However, they are not suitable for rooms fitted with live racks with roller conveyors as the thaw water can drip on to the rollers, freeze and cause the conveyors to cease. Finned tube evaporators are better adapted to large cold rooms that use mainly rack storage where the siting of coils and racks can be so determined as to avoid the defrosting operation interfering with stacking and rack operations. They are suitable where the refrigerant charge for the system has become problematic and calls for careful design and where the hot gas supply is greater than normal.