The potential industrial applications of curved tubes for single- and two-phase flow are reviewed within the context of physics of flow, trends in the development of technology, and its laboratory to industrial-scale commercialization. Comparison of the performance of curved tube configurations demonstrates its edge over the conventional motionless mixers, heat exchangers, and reactors. Alongside, their respective advantages and limitations are also highlighted. Further, a compendium of the available correlations for single- and two-phase friction factor and heat- and mass-transfer coefficient in curved tubes has also been presented. Key issues regarding the design parameters governing the performance of the curved tubes for mixing and heat- and mass-transfer that impact the research, development, and scale-up or scale-down of such devices are also analyzed. Emerging trends for the development of a new class of curved tubes, namely, inverters and serpentine and chaotic devices are also presented.

A Review on the Potential Applications of Curved Geometries in Process Industry

The “no-slip” is a fundamental assumption and generally-accepted boundary condition in rheology, tribology, and fluid mechanics with strong experimental support. The violations of this condition, however, are widely recognized in many situations, especially in the flow of non-Newtonian fluids. Wall slip could lead to large errors and flow instabilities, such as sharkskin formation and spurt flow, and hence complicates the analysis of fluid systems and introduces serious practical difficulties. In this article, we discuss slip at fluid-solid interface in an attempt to highlight the main issues related to this diverse complex phenomenon and its implications.

Slip at Fluid-Solid Interface

The influence of green banana pulp (GBP) on rheological behaviour and chemical characteristics of emulsions (mayonnaises) was investigated in this work. Five formulations were developed, using an experimental design for constrained surfaces and mixtures, with the following proportions (water/soybean oil/GBP): F1 (0.10/0.20/0.70), F2 (0.20/0.20/0.60), F3 (0.10/0.25/0.65), F4 (0.20/0.25/0.55) and F5 (0.15/0.225/0.625). Rheological properties of the emulsions were obtained with a rotational Haake Rheostress 600 rheometer and a cone and plate geometry sensor (60 mm diameter, 2° cone angle), with a gap distance of 1 mm. The samples presented high values for mineral salts and low calories. The emulsions showed pseudoplastic behaviour at 10 and 25 °C and rheological data were well described by the Herschel-Bulkley model. Formulations with high GBP content (F1 and F3) presented higher yield stress and apparent viscosity values. The results obtained with the response surface methodology, which were adjusted by the quadratic model, showed that GBP had a significant influence on the increase of yield stress and apparent viscosity. The consistency coefficient increased with an increase in soybean oil concentration and water contributed to high values of flow behaviour index in all emulsions samples.

Influence of green banana pulp on the rheological behaviour and chemical characteristics of emulsions (mayonnaises)

The temperature effect on rheological behavior of whole araca pulp was investigated in this work. The pulp was processed in a depulper with a 1.5 mm screen to obtain a uniform consistency. The rheological measurements were carried out in a concentric cylinder Brookfield rheometer, with a small sample adapter and spindle SC4-27, in a shear rate range of 2.80–70 s−1. The whole pulp was properly described by the power law model and exhibited a shear thinning behavior. The viscosity decreased with an increase in temperature; however, the viscosity showed a tendency to increase at 60 °C. The Arrhenius model gave a good description of temperature effect on apparent viscosity of the pulp, where the activation energy (Ea) determined at a shear rate of 50 s−1 was 11.03 kJ mol−1.

Influence of temperature on the rheological behavior of whole araçá pulp (Psidium cattleianum sabine)

Preface. Contributors. 1 Introduction - Why the Interpretive Approach? (Niall W. G. Young). 1.1 Rheology - What is in it for me? 1.1.1 Case study. 2 Viscosity and Oscillatory Rheology (Taghi Miri). 2.1 Introduction. 2.2 Food rheology. 2.3 Directions of rheological research. 2.3.1 Phenomenological rheology or macrorheology. 2.3.2 Structural rheology or microrheology. 2.3.3 Rheometry. 2.3.4 Applied rheology. 2.4 Steady-state shear flow behaviour: viscosity. 2.4.1 Rheological models for shear flow. 2.4.2 Wall slip. 2.5 Viscoelasticity and oscillation. 2.5.1 Oscillatory testing. 2.6 Process, rheology and microstructural interactions. 2.7 Rheology of soft solids. 2.7.1 Capillary rheometer. 2.7.2 Squeeze flow rheometer. 2.8 Measuring instruments - practical aspects. 2.8.1 Choosing the right measuring system. 3 Doppler Ultrasound-Based Rheology (Beat Birkhofer). 3.1 Introduction. 3.1.1 Overview. 3.1.2 History of ultrasonic velocimetry. 3.1.3 Existing literature on UVP-based rheometry. 3.2 Ultrasound transducers. 3.3 Flow adapter. 3.3.1 Doppler angle. 3.4 Acoustic properties. 3.4.1 Propagation. 3.4.2 Attenuation. 3.4.3 Sound velocity. 3.4.4 Scattering. 3.4.5 Backscattering. 3.5 Electronics, signal processing and software. 3.5.1 Electronics. 3.5.2 Signal processing and profile estimation. 3.5.3 Software. 3.6 Pipe flow and fluid models. 3.6.1 Gradient method or point-wise rheological characterisation. 3.6.2 Power law fluid model. 3.6.3 Herschel-Bulkley fluid model. 3.6.4 Other models. 3.7 Rheometry. 3.7.1 Averaging effects at the pipe wall. 3.7.2 Fitting. 3.7.3 Gradient method. 3.8 Examples. 3.8.1 Carbopol solution. 3.8.2 Suspension of polyamide in rapeseed oil. 3.9 Summary. 4 Hydrocolloid Gums - Their Role and Interactions in Foods (Tim Foster and Bettina Wolf). 4.1 Introduction. 4.2 Behaviour of hydrocolloid gums in solution. 4.3 Hydrocolloid gelation and gel rheology. 4.4 Hydrocolloid-hydrocolloid interactions. 4.5 Hydrocolloids in foods - role and interactions. 5 Xanthan Gum - Functionality and Application (Graham Sworn). 5.1 Introduction. 5.2 Xanthan molecular structure and its influence on functionality. 5.3 The conformational states of xanthan gum. 5.4 Food ingredients and their effects on xanthan gum functionality. 5.4.1 Salts. 5.4.2 Acids (pH). 5.4.3 Xanthan and proteins. 5.4.4 Xanthan and starch. 5.5 Food processing and its impact on xanthan gum functionality. 5.5.1 Thermal treatment. 5.5.2 Homogenisation. 5.5.3 Freezing. 5.6 Food structures. 5.6.1 Emulsions. 5.6.2 Gels. 5.7 Applications. 5.8 Future trends. 6 Alginates in Foods (Alan M. Smith and Taghi Miri). 6.1 Alginate source and molecular structure. 6.2 Alginate hydrogels. 6.3 Alginic acid. 6.4 Alginate solutions. 6.5 Enzymatically tailored alginate. 6.6 Alginates as food additive. 6.6.1 Gelling agent. 6.6.2 Thickening agent. 6.6.3 Film-forming agent. 6.6.4 Encapsulation and immobilisation. 6.6.5 Texturisation of vegetative materials. 6.6.6 Stabiliser. 6.6.7 Appetite control. 6.6.8 Summary. 7 Dairy Systems (E. Allen Foegeding, Bongkosh Vardhanabhuti and Xin Yang). 7.1 Introduction. 7.2 Fluid milk. 7.2.1 Rheological properties of milk. 7.2.2 Measurements of the rheological properties of milk. 7.2.3 Factors influencing milk rheological properties. 7.2.4 Correlating rheological properties of milk to sensory perceptions. 7.2.5 Process engineering calculation. 7.3 Solid cheese. 7.3.1 Small amplitude oscillatory tests. 7.3.2 Large strain rheological analysis. 7.3.3 Creep and stress relaxation. 7.4 Rheological properties of semi-solid dairy foods. 7.4.1 Flow properties. 7.4.2 Yield stress. 7.4.3 Viscoelastic properties of semi-solid dairy products. 7.5 Effect of oral processing on interpretation of rheological measurement. 8 Relationship between Food Rheology and Perception (John R. Mitchell and Bettina Wolf). 8.1 Introduction. 8.2 Rheology and thickness perception. 8.3 Rheology and flavour perception. 8.4 Mixing, microstructure, gels and mouthfeel. 8.4.1 Mixing. 8.4.2 Microstructure. 8.4.3 Mouthfeel. 8.4.4 Gels. 8.5 Beyond shear rheology. 8.6 Conclusions. 9 Protein-Stabilised Emulsions and Rheological Aspects of Structure and Mouthfeel (Fotios Spyropoulos, Ernest Alexander K. Heuer, Tom B. Mills and Serafim Bakalis). 9.1 Introduction. 9.2 Processing and stability of emulsions. 9.2.1 Instabilities in emulsions. 9.2.2 Protein functionality at liquid interfaces. 9.2.3 Protein-stabilised oil-in-water emulsions - Effect of aqueous phase composition. 9.2.4 Effect of processing. 9.3 Oral processes. 9.3.1 Different stages and phenomena during oral processing. 9.3.2 Fluid dynamics during oral processing. 9.3.3 Interactions with saliva. 9.3.4 Interaction with oral surfaces. 9.4 In vitro measurements of sensory perception. 9.5 Future perspectives. 10 Rheological Control and Understanding Necessary to Formulate Healthy Everyday Foods (Ian T. Norton, Abigail B. Norton, Fotios Spyropoulos, Benjamin J. D. Le Reverend and Philip Cox). 10.1 Introduction. 10.2 Design and control of material properties of foods inside people. 10.2.1 Oral perception of foods. 10.2.2 Food in the stomach. 10.2.3 Food in the intestine. 10.3 Reconstructing foods to be healthy and control dietary intake. 10.3.1 Use of emulsions as partial fat replacement. 10.3.2 Duplex emulsions. 10.3.3 Fat replacement with air-filled emulsion. 10.3.4 Sheared gels (fluid gels). 10.3.5 Water-in-water emulsions. 10.3.6 Self-structuring systems. 10.4 Conclusions. References. Index.

Krittalak Chakrabandhu

Papers

Rheological properties of coarse food suspensions in tube flow at high temperatures

Wall slip determination for coarse food suspensions in tube flow at high temperatures

Determination of food particle residence time distributions in coiled tube and straight tube with bends at high temperature using correlation analysis