Аннотация и ключевые слова
Аннотация (русский):
Methods that simulate the fast refrigeration of foods on the basis of a model of adjustable heat sink according to the principle of programmed freezing are considered. In this case, a fast freezer is seen as a system of modules, each of which can independently ensure the necessary heat-sink conditions for the fast refrigeration process. The focus is made on the analysis of physicochemical processes that form the water crystallization front at the first freezing stage, taking into account the thermophysical specifics of organizing a multizone combined system of refrigeration supply. Test-bench studies were conducted to obtain the main regularities of fast freezing of single-piece packaged dairy products by the nitrogen + air combined method in a wide range of heat-exchange conditions. The fast freezer has two freezing zones with various temperatures, allowing an efficient distribution of energy costs and creating the optimal conditions for freezing and for the continuity of the technological cycle. A mathematical model has been developed on the basis of experimental data analysis to determine the main technological parameter, the duration of food refrigeration in a nitrogen + air combined two-zone fast freezer with adjustable heat sink. The integral characteristics of the mathematical model have been determined. The model´s adequacy to the real freezing process has been proved.

Ключевые слова:
combined method, refrigeration, dairy products, fast freezer, nitrogen, temperature, zone, duration, calcu-lations


The simulation of refrigeration processes used for various foodstuffs and raw materials with precise goal setting and results obtained has been conducted by many authors, such as I.G. Alyamovskii, A.M. Brazh-nikov, K.P. Venger, D.G. Ryutov, G.B. Chizhov,  I.G. Chumak, and A.P. Sheffer. These studies were based on the theories of Planck, Stefan, Lamé, and Clapeyron, and the solution of the problem was reduced to determining the duration of food freezing to a preset volume-averaged or final temperature in the middle of the body in a criterion, dimensionless, or classical form.

The simplest dependence for determining the duration of the refrigeration process was developed by Planck. This solution is considered classical, being notable for its simplicity and ease of use. It is built on the following assumptions:

  • a homogeneous moisture-containing body is cooled to the cryoscopic temperature before refrigeration;
  • ice formation occurs without overcooling and isothermally at the cryoscopic temperature, and the thermophysical properties of the frozen part of the body's total volume do not depend on temperature, the thermal capacity of the frozen part being equal to zero, and
  • refrigeration occurs by removing heat from the body surface, the heat transfer coefficient and the temperature of the heat-sinking media being constant.

The first analytical solution to the problem of the duration of freezing a flat plate from the initial temperature, which is higher than the cryoscopic one, to the final temperature of the middle, which is below the cryoscopic one, was obtained by D.G. Ryutov and was widely recognized in refrigeration technology [1].

In order to take into account the duration of the plate's temperature decline after the convergence of phase boundaries, a linear temperature change is admissible along the thickness of the frozen layer. Further heat exchange in the plate is analyzed on the basis of the regularities of simple cooling. The time during which the temperature of the plate center decreases from the cryoscopic to the finial preset temperature is summed to the duration calculated by the Planck formula.

In order to take into account the influence of the initial temperature of the product plate on the duration of refrigeration to the heat amount removed from the mass unit during freezing, a binomial multiplier was introduced (1 +  0.0053 ti).

Alyamovskii adjusted Ryutov's formula by assuming that the temperature distributed parabolically at the initial moment of freezing [2].

V.E. Kutsakova proposed a model for calculating the duration of refrigeration of an infinite plate, characterized by a simple mathematical formula and reduced to the Planck formula, taking into account the period of further freezing and the process of crystallization front movement. The model assumes a linear approximation of the temperature field of the material along the axis of temperature front distribution at the stages of refrigeration and the period of relaxation of the temperature field [3].


Список литературы

1. Ryutov, D.G. and Khristodulo, D.A., Bystroe zamorazhivanie myasa (Fast Freezing of Meat) (Pishchepromizdat, Moscow, 1956). 140 p.

2. Alyamovskii, I.G., Geints, R.G., Golovkin, N.A., et al., Analiticheskoe issledovanie tekhnologicheskikh protsessov obrabotki myasa kholodom (Analytical Study of Processing Meat with Cold) (TsNIITEImyasomolprom, Moscow, 1970). 183 p.

3. Kutsakova, V.E., Frolov, S.V., Yakovleva, M.I., et al., About freezing time of foods. Kholodil´naya tekh. (Refrigeration Equipment), 1997. № 2. P. 16-17.

4. Stefanovskii, V.M., A new method of calculating the duration of meat refrigeration, Kholodil´naya tekh. (Refrigeration Equipment), 1989. № 11. P.15-19.

5. Brazhnikov, A.M., Teoriya termicheskoi obrabotki myasoproduktov (Theory of Thermal Processing of Meat Products) (Agropromizdat, Moscow, 1987). 270 p.

6. Leibenzon, L.S., On the problem of solidification of the terrestrial globe from its molten state, Tr. Akad.Nauk SSSR, 1965. V. 4.

7. Venger, K.P. and Antonov, A.A., Azotnye sistemy khladosnabzheniya dlya proizvodstva bystrozamorozhennykh pishchevykh productov (Nitrogen Cold-Supply Systems for the Production of Fast-Frozen Foods). (Uzorech´e, Ryazan´, 2002). 207 p.

8. Lobanov, I.E., Babakin, B.S., Aitikeev, R.B., Voronin, M.I., and Babakin, S.B., Mathematical model of the ice buildup process on a spherical surface for cold accumulators, Vestn. Int. Acad. Refrigeration, 2013. № 4. p. 12-15.

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14. Buyanov, V.O., Larina, I.O., Buyanova, I.V., and Kriger, O.V., The role of low temperatures in assessing the microbiological condition of frozen cheeses, Syrodelie maslodelie (Cheesemaking Buttermaking), 2008. № 3. P. 25-26.

15. Li, Ruixia and Wang, Weicheng, Qinghua daxue xuebao. Ziran kexue ban, J. Tsinghua Univ. Sci. and Technol., 2006. V. 46. № 5.

16. Coulomb, D., World tendencies and priorities in development of low-temperature engineering, Vestn. Int. Acad. Refrigeration, 2012. № 4. P. 3-7.

17. Buyanov, O.N. and Buyanova, I.V., Current technologies of freezing and storing dairy products, Pererabotka moloka (Milk Processing), 2010. № 4. P.36-38.

18. Antonov, A.A. and Venger, K.P., Technical and economic assessment of the operation of fast freezers, Myasnaya industriya (Meat Industry), 2002. № 6. P. 40-42.

19. Buyanov, V.O., Development of a technology of the combined fast freezing of foods. Extended Abstract of Cand. Sci. (Eng.) Dissertation. (Kemerovo, 2009). 18 p.

20. Latyshev, V. and Tsiryul´nikova, N., Standardization of the properties of foods, Kholodil´naya tekh. (Refrigeration Equipment), 1990. № 2. P. 33-34.

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