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Ice Slurry Generation Based on Sugar-Ethanol Aqueous Solution
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Ice Slurry Generation Based on Sugar-Ethanol Aqueous Solution

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Miguel León M., Rocío Rodríguez G., Juan J. Milón G., Sergio L. Braga...

Miguel León M., Rocío Rodríguez G., Juan J. Milón G., Sergio L. Braga
Technological Research Laboratory in Energy San Pablo Catholic University
Energy Institute, PUC-RIO Pontifical Catholic University of Rio de Janeiro

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Ice Slurry Generation Based on Sugar-Ethanol Aqueous Solution Ice Slurry Generation Based on Sugar-Ethanol Aqueous Solution Document Transcript

  • R005, Page 1 Ice Slurry Generation Based on Sugar-Ethanol Aqueous Solution Miguel León M.1, Rocío Rodríguez G.1, Juan J. Milón G.1, 3, Sergio L. Braga2 1 Technological Research Laboratory in Energy San Pablo Catholic University Av. Salaverry 301, Vallecito Tel (+51-54-285600), Fax (+51-54-281517), Email: milonjj@ucsp.edu.pe 2 Energy Institute, PUC-RIO Pontifical Catholic University of Rio de Janeiro Rua Marquês de Sao Vicente, 225, Gávea, Rio de Janeiro Tel.: (55 21) 3114-1535 Fax: (55 21) 3114-1543, Email: slbraga@mec.puc-rio.br 3 Corresponding Author ABSTRACT An experimental device was developed for the ice slurry generation with sugar-ethanol aqueous solution. Different concentrations were used for futures application in freezing for conservation and transports. Temperatures varying with time were measured in the ice slurry generator. The temperature sensors were type K thermocouples, a data acquisition is a multifunctional system with acquisition interval of 1 second. The results indicate that the ice slurry generation depends on the sugar and ethanol concentration. The ice slurries generation with sugar-ethanol aqueous solution, can be applied for the product cooling with low tolerance to ice slurry generated with high ethanol, sugar and sodium chloride concentrations. 1. INTRODUCTION Ice slurries are also known under the trade names of Flo-Ice, Binary Ice, or Pumpable Ice. At the moment, the ice slurry generation, is oriented to the use of components that are adapted to the product to be cooled, for example, with sodium chloride for marine products and ethanol for industrial processes. For the cooling of products like fruits and vegetables, no one of the previous types of ice slurry is adapted; this will cause the product contamination by the used components (sodium chloride, ethanol, etc.). The present paper studies the possibility of ice slurry generation with low contents of ethanol and sugar to the cooling of different products. Binary or ternary aqueous solutions containing soluble carbohydrates (e.g. sucrose, invert sugar, glucose (dextrose), fructose and other mono and disaccharides) with additions of ethanol, salts, glycerol, etc. can be made (Fikiin et al, 2003). . 2. EXPERIMENTAL MODEL In figure 1, we can observe the four elements in the experimental model: compressor, condenser (tube-fin with forced convection), expansion valve (thermostatic type) and evaporator (type submerged). In the evaporator the refrigerant absorbs heat of the mixture (water, alcohol, and sugar. International Refrigeration and Air Conditioning Conference at Purdue, July 17-20, 2006
  • R005, Page 2 Figure 1: Scheme of the experimental model (left) and the detail of the submerged evaporator (right) 2.1 Test Section The test section is formed by the evaporator as showed in the Fig. 2 (a). The scraper and the mixer in the evaporator are shown in detail (b, c in the Fig. 2), respectively. a b c Figure 2: Test section details. The evaporator is of a type submerged, the coolant is an R-410A refrigerant, two agitators and a helical scraper which is made of stainless steel. The aqueous solution (with methanol and sugar) is placed within the evaporator to diminish the temperature of the mixture and to obtain finally the ice slurries. 2.2 Data Acquisition System The measurements and storage of data are made by the data acquisition system and a personal computer (PC). The acquisition equipment which communicates with the PC by the RS232 communication port, receives, processes and transmits the temperature signals to PC, for storage and posterior analysis. The data acquisition system used was the OMEGA model Temp Scan 1100. For the temperature measurement were used four thermocouples type K with diameter 0.017 mm. International Refrigeration and Air Conditioning Conference at Purdue, July 17-20, 2006
  • R005, Page 3 Three thermocouples were placed into the ice slurry evaporator (bottom, middle and top position); the other thermocouple was used to measure the external temperature. 3. EXPERIMENTAL PROCEDURE Stage I: The water-sugar-ethanol mixture is placed within the evaporator to 25 ºC Stage II: The data acquisition system and ice slurry generator were activated at the same time. Stage III: Is observed the agglomeration in the ice slurry (in each test). The duration of each test varies from 1 to 5 hours, depending of the test conditions. The data is acquired once a second. If the ice slurry were not generated in 5 hours, the test was stopped. Uncertainties of the measurements are presented in Table 1. Table 1: Uncertainties of measurements Parameter Uncertainty Temperature 0.1 ºC Time 0.01 s Length 0.01 mm 3.1 Investigated parameters Tests for ethanol concentrations were made of 1.43; 2.86; 5.0 y 7.14 (% per mass), and for the sugar were used concentrations of 4.0; 7.14; 10.0; y 12.9 (% per mass). For each ethanol concentration, the concentration of sugar was varied, maintaining constant the mixture mass (7 kg for each test). 4. RESULTS The variation of the temperature of the ice slurries with the sugar and ethanol concentration can be observed in Fig 3. It can be appreciate that as it is increased the concentration of sugar and ethanol, the temperature of the ice slurry decreases. 0 -1 Ice Slurry Temperature, ºC -2 -3 1.4 2.8 Ethanol Concentration, % 5 per mass 7.1 -4 2 4 6 8 10 12 Sugar Concentration, % per mass Figure 3: Ice Slurry Temperature and Sugar Concentration. International Refrigeration and Air Conditioning Conference at Purdue, July 17-20, 2006
  • R005, Page 4 In fig 4, the variation of the generation time of the ice slurries with the sugar and ethanol concentration can be observed. As it is increased the concentration of sugar and ethanol, the ice slurry generation time increases. Also it is possible to be observed that for the case of the ethanol concentration of 1.4 (% per mass), the time of generation remains considerably constant. This last test is considered the most optimal for the ice slurry generation with sugar and ethanol. 12000 11000 Time of Ice Slurry Generation, s 10000 9000 8000 1.4 7000 2.8 Ethanol Concentration, % 5 per mass 6000 7.1 5000 2 4 6 8 10 12 Sugar Concentration, % per mass Figure 3: Time of Ice Slurry Generation and Sugar Concentration. 5. CONCLUSIONS As it is increased to the concentration of sugar and ethanol, the temperature of the ice slurry decreases. As it is increased the concentration of sugar and ethanol, the ice slurry generation time increases. The minimum concentrations of sugar and ethanol to ice slurry generation were of 4.0 and 1.4%, respectively, this concentration is considered optimal to make future applications in the cooling process of different product. REFERENCES Fikiin, K., Tsvetkov, O., Yu. Laptev, Fikiin, A. and Kolodyaznaya, V., 2003, Immersion Freezing of Fruits in Ice Slurries Based on Sugar-Ethanol Aqueous Solution. Thermophysical and Engineering Issues. Ticona, E.M., 2003, Determinação Experimental do Coeficiente de Troca de Calor em um Gerador de Pasta de Gelo. Dissertação de mestrado. Pontificia Universidade Católica do Rio de Janeiro. Jimenez, H., 2003, Determinação Experimental dos Coeficientes de Transporte em um Intercambiador de Calor de Placas. Dissertação de Mestrado. Pontificia Universidade Católica do Rio de Janeiro. ACKNOWLEDGEMENT The authors also wish to thank the Agreement Pontificia Universidade Católica do Rio de Janeiro and Universidad Católica San Pablo for motivating this research work. International Refrigeration and Air Conditioning Conference at Purdue, July 17-20, 2006