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Product Temperature (product + temperature)
Selected AbstractsEnergy consideration for designing supercharged ram jet enginesINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 2 2008Amro M. Al-QutubArticle first published online: 20 JUN 200 Abstract The present work investigates the energy considerations and performance characteristics of a newly proposed supercharged ram jet engine. Thermodynamics and fluid mechanics analyses were developed to predict specific thrust, thrust-specific fuel consumption (TSFC), overall efficiency, and thrust-to-weight ratio of the engine. Compressor pressure ratio and efficiency, combustor temperature, and pressure losses in the burner and nozzle are considered as primary variables in the engine performance analysis. Performance characteristics are calculated to illustrate the effect of each parameter independently at different flight speeds. This is done while maintaining other parameters at given typical operating values. A computer program was developed to perform the iterative calculations. Results indicate that the compressor pressure ratio and the combustion product temperature are the most critical parameters in determining the performance of the engine. At compressor pressure ratio of 1.15,1.2, the typical static thrust-to-weight ratio is at maximum. Increasing combustion product temperature increases the thrust-to-weight ratio as well as TSFC. Finally, newly developed high power-to-weight ratio IC engine makes it possible for the supercharged ram jet engine to achieve high performance, in terms of thrust-to-weight ratio and TSFC. Copyright © 2007 John Wiley & Sons, Ltd. [source] Original article: Apparent thermal diffusivity estimation for the heat transfer modelling of pork loin under air/steam cooking treatmentsINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 9 2010Massimiliano Rinaldi Summary Apparent thermal diffusivity linear functions vs. product temperature were estimated for pork cooked under two different treatments (forced convection, FC and forced convection/steam combined, FC/S) at 100, 110, 120 and 140 °C by means of experimental time,temperature data and a developed finite-difference algorithm. Slope and intercept of each function were employed to calculate apparent thermal diffusivity at 40, 55 and 70 °C. Generally, FC/S treatments gave significantly higher apparent thermal diffusivities in comparison with FC conditions. Apparent thermal diffusivities were used to develop a model for cooking time and final core temperature prediction on the basis of oven setting. The model was validated by means of additional cooking tests performed at different temperatures of those employed for model development. Root mean square error values lower than 3.8 °C were obtained comparing predicted and experimental temperature profiles. Percentage errors lower than 3.1% and 3.5% were, respectively, obtained for cooking times and final core temperatures. [source] Prediction of cooling time in injection molding by means of a simplified semianalytical equationADVANCES IN POLYMER TECHNOLOGY, Issue 3 2003D. M. Zarkadas Abstract A simplified semianalytical equation, used successfully in food freezing/chilling time prediction, is proposed as a potential simple alternative for cooling time prediction in injection molding of polymer parts, amorphous or semicrystalline. This equation is based on a convective boundary condition for the mold-part interface and requires information on the thermal contact resistance (TCR) or thermal contact conductance (TCC) at this interface, as well as information on the initial and final product temperatures, the mold surface temperature, and the thermal properties of the part. Eighty-five data points for four polymers, Polystyrene (PS), Polycarbonate (PC), Polypropylene (PP), and Polyethylene (PE) were generated with C-MOLDŌ, a commercial injection molding design software, and the performance of the proposed equation was tested. The % mean error and its standard deviation (SD) in cooling time prediction were, respectively, ,11.61 and 2.27 for PS, ,6.04 and 2.13 for PC, ,7.27 and 6.55 for PP, and ,8.88 and 2.93 for PE. It was also shown that the accuracy of the proposed equation is not affected significantly by the exact knowledge of the TCC, provided that the latter is not smaller than 1000,2000 W m,2 K,1. Since in this comparison all necessary temperatures were obtained from C-MOLDŌ, methods of using the proposed equation independently were tested. The use of the inlet melt temperature as the initial product temperature increased the % mean error by mostly 1.5% while its SD remained practically the same. By incorporating a literature based heat balance method in the proposed equation, it was possible to use it as a stand-alone predictor of polymer cooling time. The % mean error and its SD calculated this way were, respectively, ,9.44 and 0.97 for PS, ,9.44 and 0.83 for PC, ,14.22 and 5 for PP, and ,20.12 and 1.38 for PE. The proposed equation, at least in a preliminary stage, can be used successfully to predict the cooling time of the selected semicrystalline or amorphous polymers with the accuracy being higher for amorphous polymers. © 2003 Wiley Periodicals, Inc. Adv Polym Techn 22: 188,208, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.10048 [source] NEW GENERATION OF HEALTHY SNACK FOOD BY SUPERCRITICAL FLUID EXTRUSIONJOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 2 2010K.Y. CHO ABSTRACT A supercritical fluid extrusion (SCFX) process has been successfully developed for the production of a novel healthy snack containing 40,60 wt% protein with unique porous structure and texture. Supercritical carbon dioxide (SC-CO2) injection rate and product temperature at the die were found to be critical to control the expansion and texture of the final product. Maximum cross-sectional expansion was obtained at 0.3 wt% added SC-CO2, whereas more uniform internal structure was achieved at 0.7 wt% SC-CO2 level. As whey protein concentrate (80 wt%) concentration was increased from 52.8 to 78.2 wt% in the formulation, the cross-sectional expansion of baked and fried products increased by 65.8 and 44.4%, respectively. It was observed that lower viscosity of whey protein compared with starch decreased expansion but helped enhance further expansion during post-extrusion drying. The finding showed that an extrusion process at the temperature below protein denaturation temperature using SC-CO2 can help to prevent hard texture due to the thermosetting property of whey protein and to create a uniformly expanded structure. The textural properties of SCFX chips were comparable to commercial extruded or fried chip products. PRACTICAL APPLICATIONS The American snack market is one of fast-growing markets in the world as snacking becomes more popular. Because of the increasing concerns about health, there is also an increasing demand for new healthy snacks as an alternative for fried starch-based snacks with low nutrient density. This study shows the potential of supercritical fluid extrusion (SCFX) technology for healthy snack food production containing whey protein. SCFX chips had uniform cellular microstructure that cannot be obtained using conventional steam-based extrusion. As supercritical carbon dioxide can deliver certain flavors, an expanded snack not only with high nutrient density and unique texture but also with encapsulated flavors can be produced using the SCFX process and can be marketed as a novel healthy snack. [source] EFFECT OF OSMOTIC TREATMENT WITH CONCENTRATED SUGAR AND SALT SOLUTIONS ON KINETICS AND COLOR IN VACUUM CONTACT DRYINGJOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 6 2007S.M.A. RAHMAN ABSTRACT An experimental study of osmotic dehydration (OD) of selected heat-sensitive products was carried out in a laboratory-scale vacuum contact dryer. Cubes of potato and apple were examined as model heat-sensitive objects. Experiments were conducted at different conduction heat input levels with wall temperatures in the range 35,45C under vacuum and also in pure vacuum without any external heat input. Detailed investigations were carried out of OD on drying performance, product temperature and color of the dried product. PRACTICAL APPLICATIONS Osmotic treatment of potato and apple samples using concentrated sugar solution shows better osmotic dehydration as well as drying rate in a vacuum contact drying system. This information may help to select the osmotic agent in any industrial application for faster drying rate in vacuum contact drying specially for food products. Moreover this work shows the analysis to find out the starting point of precipitation of osmotic agent inside the products in terms of drying time, temperature and moisture content. This information will be helpful for critical analysis in osmotic dehydration technique which in turns may help for optimum design. [source] EXTRUSION COOKING OF BLENDS OF SOY FLOUR AND SWEET POTATO FLOUR ON SPECIFIC MECHANICAL ENERGY (SME), EXTRUDATE TEMPERATURE AND TORQUEJOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 4 2001M. O. IWE Defatted soy flour and sweet potato flour containing 18% moisture were mixed in a pilot mixer, and extruded in an Almex-Bettenfeld single-screw extruder operated at varying rotational speed and die diameter. A central composite, rotatable nearly orthogonal design, which required 23 experiments for three factors (feed composition (fc), screw speed (ss) and die diameter (dd)) was developed and used for the generation of response surfaces. Effects of the extrusion variables on specific mechanical energy (SME), extrudate temperature (ET), and torque (T) were evaluated using response surface analysis. Results showed that product temperature increased with increases in die diameter, screw speed and feed composition. However, the effect of die diameter was greater than those of screw speed and feed composition. Decrease in die diameter with increase in sweet potato content increased torque. Screw speed exhibited a linear effect on torque. [source] Hydrodynamic Cavitation: Characterization of a Novel Design with Energy Considerations for the Inactivation of Saccharomyces cerevisiae in Apple JuiceJOURNAL OF FOOD SCIENCE, Issue 6 2008P.J. Milly ABSTRACT:, A Shockwave PowerŌ Reactor consisting of an annulus with a rotating pock-marked inner cylinder was used to induce hydrodynamic cavitation in calcium-fortified apple juice flowing in the annular space. Lethality on Saccharomyces cerevisiae was assessed at processing temperatures of 65 and 76.7 °C. Details of the novel equipment design were presented and energy consumption was compared to conventional and pulsed electric fields processing technologies. The mean log cycle reduction of S. cerevisiae was 6.27 CFU/mL and all treatments resulted in nonrecoverable viable cells. Induced lethality from hydrodynamic cavitation on S. cerevisiae exceeded the predicted values based on experimentally determined thermal resistance. Rotation of 3000 and 3600 rpm at flow rates greater than 1.0 L/min raised product temperature from 20 to 65.6 or 76.7 °C, respectively, and energy input was less than 220 kJ/kg. Conversion efficiency from electrical to thermal was 55% to 84%. Hydrodynamic cavitation enhanced lethality of spoilage microorganisms in minimally processed juices and reduced energy usage. [source] Improving Grape Quality Using Microwave Vacuum Drying Associated with Temperature ControlJOURNAL OF FOOD SCIENCE, Issue 1 2007C. D. Clary ABSTRACT:, Microwave (MW) vacuum dehydration using temperature to control the level of MW power demonstrated potential in improving the performance of the process. Product surface temperature measured by an infrared temperature sensor was used to control MW power at any level between 0 and 3 kW. Multiple linear regression analysis indicated an r2= 0.942 for prediction of final moisture content and r2= 0.985 for prediction of puffed character of grapes based on product temperature, time, specific energy, fresh fruit sugar, and fresh fruit moisture content. Temperature was found to be the most significant predictor. The elemental and compound contents of grapes dried using MW vacuum was compared to sun-dried raisins. The grapes dried using MW vacuum exhibited better preservation. Vitamin A was found in the MW-vacuum-dried grapes but none was detected in the raisins, and Vitamin C, thiamine, and riboflavin were also higher in the MW-vacuum-dried grapes than in the raisins. [source] Kinetics of Lysine and Other Amino Acids Loss During Extrusion Cooking of Maize GritsJOURNAL OF FOOD SCIENCE, Issue 2 2003S. Ilo ABSTRACT: Maize grits were extrusion-cooked in a conical, counter-rotating twin-screw extruder at different barrel temperatures, feed moistures, and screw speeds. Residence time distribution was measured by a dye tracer technique. Experiments with lysine-fortified maize grits showed a 1st order reaction for lysine loss. A detailed kinetic study has been performed for the losses during extrusion cooking of lysine, cystine, and arginine. The 1st-order rate constants were dependent mainly on product temperature and feed moisture, whereas screw speed had no influence. Activation energy of lysine, arginine, and cystine loss was 127, 68, and 76 kJ/mol, respectively. Shear stress significantly affected the rate constants of amino acids loss in extrusion cooking. [source] Mannitol,sucrose mixtures,versatile formulations for protein lyophilizationJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 4 2002Robert E. Johnson Abstract Mixtures of sucrose (a lyoprotectant) and mannitol (a bulking agent) have been investigated as excipients for the lyophilization of proteins. Four proteins under development have been successfully lyophilized in a formulation of 4% mannitol and 1% sucrose using a lyophilization cycle that produces a cake of crystalline mannitol and amorphous sucrose. The crystalline mannitol allows primary drying to be performed with a product temperature of ,10°C even though the sucrose is amorphous and, by itself, would have required primary drying below ,35°C to avoid cake collapse. Formation of an unstable mannitol hydrate is avoided by conducting secondary drying at 40°C or higher. © 2002 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 91: 914,922, 2002 [source] Prediction of cooling time in injection molding by means of a simplified semianalytical equationADVANCES IN POLYMER TECHNOLOGY, Issue 3 2003D. M. Zarkadas Abstract A simplified semianalytical equation, used successfully in food freezing/chilling time prediction, is proposed as a potential simple alternative for cooling time prediction in injection molding of polymer parts, amorphous or semicrystalline. This equation is based on a convective boundary condition for the mold-part interface and requires information on the thermal contact resistance (TCR) or thermal contact conductance (TCC) at this interface, as well as information on the initial and final product temperatures, the mold surface temperature, and the thermal properties of the part. Eighty-five data points for four polymers, Polystyrene (PS), Polycarbonate (PC), Polypropylene (PP), and Polyethylene (PE) were generated with C-MOLDŌ, a commercial injection molding design software, and the performance of the proposed equation was tested. The % mean error and its standard deviation (SD) in cooling time prediction were, respectively, ,11.61 and 2.27 for PS, ,6.04 and 2.13 for PC, ,7.27 and 6.55 for PP, and ,8.88 and 2.93 for PE. It was also shown that the accuracy of the proposed equation is not affected significantly by the exact knowledge of the TCC, provided that the latter is not smaller than 1000,2000 W m,2 K,1. Since in this comparison all necessary temperatures were obtained from C-MOLDŌ, methods of using the proposed equation independently were tested. The use of the inlet melt temperature as the initial product temperature increased the % mean error by mostly 1.5% while its SD remained practically the same. By incorporating a literature based heat balance method in the proposed equation, it was possible to use it as a stand-alone predictor of polymer cooling time. The % mean error and its SD calculated this way were, respectively, ,9.44 and 0.97 for PS, ,9.44 and 0.83 for PC, ,14.22 and 5 for PP, and ,20.12 and 1.38 for PE. The proposed equation, at least in a preliminary stage, can be used successfully to predict the cooling time of the selected semicrystalline or amorphous polymers with the accuracy being higher for amorphous polymers. © 2003 Wiley Periodicals, Inc. Adv Polym Techn 22: 188,208, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.10048 [source] COFFEE DRYING IN A ROTARY CONDUCTION-TYPE HEATING UNITJOURNAL OF FOOD PROCESS ENGINEERING, Issue 2 2004GIKURU MWITHIGA ABSTRACT Parchment coffee (Arabica) was dried from an initial moisture content of about 90% to 10% dry basis (db) in a recirculating rotary conduction type heating unit at controlled plenum temperatures of 100, 120 and 140C or controlled product temperatures of 50, 60, and 70C. the temperature of the plenum or moving beans could be maintained at specified levels with small variations during coffee drying experiments. the color and specific gravity of coffee beans exhibited minimum changes as a result of drying operations. the susceptibility of coffee beans to breakage decreased with the lowering of moisture and attained minimum values in the moisture content range of 20 to 30% db. the breakage susceptibility increased sharply with further reduction in moisture content. A drying model, which considered product temperature-time history alone under different operating conditions, estimated the change in moisture content adequately. Such a model could be used for computer-based control of the coffee drying process. [source] USE OF EXTRUSION-TEXTURIZED WHEY PROTEIN ISOLATES IN PUFFED CORN MEALJOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 2010C.I. ONWULATA ABSTRACT Adding whey protein concentrates or isolates to expanded snack foods would boost their nutritional content; however, adding non-textured whey proteins in amounts larger than 5% interferes with expansion, making the products less crunchy. To counter this effect, whey protein isolate (WPI) was first extruded (texturized) at either 50C (WPI-50) or 90C (WPI-100) before adding to corn meal at 25% (WPI) level, and was extruded again to make the puffed product. Corn meal, corn meal with non-texturized WPI (25%), corn meal with WPI-50, or corn meal with WPI-100 were extruded at high shear conditions (300 rpm) and product temperatures of 125C. All extrudates containing texturized WPI were more expanded, firmer, crispier and easier to break than corn meal or corn meal with non-texturized WPI. Pre-texturizing whey proteins and using them in extruded snacks improves textural properties, making it possible to add large amounts of whey proteins directly into expanded snacks to fortify them. PRACTICAL APPLICATIONS This study determined that it is better to modify whey protein isolates (WPI) before adding them to the corn meal and extruding them to create crunchy products. The process described shows that modifying the structure of the whey proteins creates a form of WPI that is more compatible with corn meal. This knowledge allows the creation of nutritious high-protein expanded crunchy snacks. [source] | ||||||||||