บทคัดย่องานวิจัย

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Increasing the energy efficiency of icemaking by continuous solidification and hydraulic harvesting.

Boyette, Michael Doyle.

Thesis (Ph. D.), Department of Biological and Agricultural Engineering. North Carolina State University. 1990. 147 p.

1990

บทคัดย่อ

INCREASING THE ENERGY EFFICIENCY OF ICEMAKING BY CONTINUOUS SOLIDIFICATION AND HYDRAULIC HARVESTING.

As much as a fifth of the fresh fruit and vegetables produced worldwide may be wasted due to inadequate postharvest cooling.  Ice is a useful and versatile cooling medium for many of these products.  In addition, ice may be utilized for thermal sink allowing the efficient use of equipment and energy resources.  Energy constitutes the largest portion of the variable cost of icemaking.  The removal of ice from the freezing surfaces of an icemaker can consume as much as a quarter of the total energy input.  This removal is normally effected by the intermittent warming of the freezing surfaces.

 This study was conducted to determine if ice could be produced continuously by passing water through a refrigerated tube and to determine if the ice could be removed or harvested from the refrigerated surfaces by the application of hydrostatic pressure alone.

 A cylindrical tube icemaker was designed, built and tested.  The device consisted of a finned aluminum circular tube enclosed in a refrigerating jacket.  The lower end of the tube was connected to a high pressure pump while the upper end remained open.  Water introduced into the lower end by the pump at a metered rate froze into a solid ice cylinder.  The hydrostatic pressure developed by the pump overcame the adhesive shear strength of the ice on the cylinder walls forcing the ice out the open upper end.  There are no moving refrigerated parts.

 --5 C.  The ratio of the power required to harvest the ice to the power required to freeze the ice was proportional to the process temperature and ranged from 3.5 to 1.5 percent, respectively.  The temperature of the ice exiting the icemaker is well below freezing allowing for convenient dry transportation, storage and use.  A cylindrical tube icemaker, operating continuously and relying only on hydrostatic pressure for harvesting has been shown possible.  The energy savings appear to be significant.