ABSTRACT A systematic procedure for testing the accuracy of freezing time prediction methods is discussed. It involves carrying out predictions by an accurate numerical method as well under test, and careful cross‐checking errors correlation with a number physical parameters. Criteria are given selection appropriate method. The need illustrated comparisons between four recent methods. show strengths weaknesses They also indicate general shortcomings in available data, so highlight those...

ABSTRACT The problem of onedimensional heat transfer in finite slabs freezing food materials cooled from both sides is considered. authors’ modification to Plank's equation compared with a numerical scheme. paper shows that the important slab simple formula, based on an approximate analytical solution, at least as accurate complex difference formulation, and has some substantial practical advantages.

ABSTRACT A series of experiments was carried out to determine the freezing time cylindrical and spherical blocks a widely used food analogue material. These results were assess accuracy calculation methods in literature, including both numerical (computer) modified analytical methods. three‐level implicit finite difference scheme developed which gave good accuracy, but no better than an extension method is therefore advocated on grounds ease use. It covers range, conditions most likely be...

ABSTRACT A previous study of methods for predicting the freezing times slabs, cylinders and spheres was extended to cover rectangular bricks food materials. Experimental measurements time were made over a wide range conditions using analogue material, these results compared calculated from various available prediction methods. The three‐dimensional version three time‐level finite difference scheme found be most accurate numerical solution. Simple formulae are geometric factors derived by...

Summary In this study we analysed the relationship between bacterial community structures and geochemistry of groundwater in a sandstone aquifer (SIReN site) impacted mainly by BTEX hydrocarbons (benzene, toluene, ethylbenzene xylenes), which benzene is most abundant. The long‐term presence reduced diversity: groundwaters contaminated with more than 1.8 × 10 4 µg l −1 benzene, diversity was half that clean groundwaters. Terminal restriction fragment length polymorphism (T‐RFLP) analysis 16S...

ABSTRACT A modification to an empirical food freezing time prediction formula is proposed that allows the be used for a range of final product temperatures. Over large data set (275 runs) percentage difference between experimentally measured times and predictions has mean 0.2% standard deviation 6.8% improved compared ‐2.4% 8.5%, respectively, prior modification. Ninety percent predicted by new method were within ± 11% 9% accurate finite scheme. This performance compares favorably with other...

Fifty-four bacterial strains were isolated from the Tongariro National Park activated sludge. Of these, only 4 capable of forming floc in proteose peptone-yeast extract (PPYE) but 6 Pseudomonas sp. produced synthetic sewage. The sludge was easily reconstructed by mixing bacteria at random. chemical oxygen demand (COD) removal activities these sludges twice as much that original pure cultures had almost same activity sludge.Sugar components, NH3-extracted fraction polymer, mainly glucose, and...

ABSTRACT Two simple methods for predicting the freezing times of rectangular bricks, slabs, cylinders, and spheres in situations where boundary conditions change with time are proposed. These based on numerical integration a differential equation derived from previously proposed modification to Plank's equation. The were tested against three time‐level finite difference scheme varying cooling medium temperatures surface heat transfer coefficients. Agreement was generally good (difference...