WHOLE ORGAN FREEZING AND THAWING HEAT TRANSFER AND THERMAL PROPERTIES.
Annual rept. 1 Apr 67-31 Mar 68,
GEOSCIENCE LTD LA JOLLA CALIF
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Numerical freezing solutions were used to predict the transient freezing histories of thin slabs of biological specimens with varying percentages of water content and specimen thickness. From such analyses, freezing times and temperature-time gradients were determined as a function of water content. A number of freezing experiments were performed with bovine liver samples, using liquid nitrogen and dry ice-acetone as refrigerants. The experimental time-temperature results were compared to predicted values obtained from a numerical analysis for an idealized liver slab. Several improvements in the thermal conductivity apparatus were made. The systems involved were checked using water. Also, some preliminary thermal conductivity measurements for bovine kidney at room temperature and at -45F were obtained. A compilation is made of all the experimentally determined heat capacities of frozen bovine spleen, skin, kidney, heart muscle, liver, brain, suet and ice and pure protein powder. The heat capacities of bovine brain, heart and liver were predicted from the classical heat capacity equation for mixtures predicted values were lower than the experimental ones. An experiment was performed to measure the heat release rate in simulated tissue material in which carbonyl iron powder was suspended. A high frequency induction field generated volumetric heat sources which would appreciably increase frozen tissue thaw rates. Author
- Anatomy and Physiology
- Medicine and Medical Research