Bk Dutta Mass Transfer Book Pdf

[Santi Dubrova]

Inconvective mass transfer, much like in convective heat transfer, systems are modeled by dint of correlations between dimensionless groups. Dimensional analysis reveals that there are three such parameters of interest in typical convection mass transfer problems. The first is the Sherwood number, which can be viewed as a ratio of the intensity of convective mass flux to the intensity of diffusive mass flux, and is mathematically expressed as

where and are parameters that depend on the geometry being modeled. The fact that implicitly implies that the mass transfer coefficient is proportional to the mass diffusivity taken to the 2/3 power, which is consistent with many experimental results. For some situations, 1/3 and we may write a general correlation of the form

The two foregoing correlations are analogous to the Dittus-Boelter correlation for heat transfer over a flat plate. Since the Dittus-Boelter heat transfer equations are valid for Prandtl numbers greater than 0.6, we may surmise that these analogous mass transfer equations should be valid for Sc > 0.6 only.

Air at 1 atm and 100C containing small particles of uranium dioxide is flowing at a velocity of 4 m/s inside a 0.15-m-diameter tube. Calculate the mass transfer coefficient for , given the kinematic viscosity of air = m/s and the mass diffusivity = m/s.

Consider a 5-m x 5-m wet concrete patio with an average water film thickness of 0.3 mm. Now wind at 50 km/h is blowing at the surface. If the air is at 1 atm, 15C, and 35 percent relative humidity, determine how long it will take for the patio to dry completely. The mass diffusivity of water vapor in air at 15C may be taken as m/s, and the saturation pressure of water at the temperature of interest is 1.71 kPa. The density and kinematic viscosity of air at the temperature of interest are 1.225 kg/m and m/s, respectively.

Observing that the air at the water surface will be saturated and that the saturation pressure of water at 15C is 1.71 kPa, the mass fraction of water vapor in the air at the surface and at the free stream conditions are respectively

A naphthalene ball of 1 cm diameter is suspended in a stream of air flowing at a velocity of 5 m/s at 50C and 1 atm total pressure. Calculate the time required for its diameter to be halved. The sublimation pressure of napthalene at the temperature of interest is 0.87 mmHg. The mass diffusivity of naphthalene in air at the temperature of interest is = m/s and the density of solid naphthalene at 50C is = 1130 kg/m. The density and viscosity of air at the temperature of interest are = 1.09 kg/m and = Pa-s, respectively.

Montogue also offers a free quiz on mass transfer by diffusion, which can be found here. Since convection mass transfer is analogous to convective heat transfer, students would do well to check out our free materials on internal convection, external convection, and natural convection. Enjoy!

Adsorption process is the fundamental principle for several advanced technologies like purification and separation technology, refrigeration and heat pumps, thermal and gas storage, desalination, and atmospheric water harvesting. In all these applications the adsorbent material cyclically adsorbs and desorbs the adsorbate for continuous operation. This rate of adsorption depends on several factors such as the properties of the adsorbent, the operating conditions, and the geometry of the adsorption bed. Most adsorption beds use a columnar packing design. Heat and mass transfer occurring within this packed adsorbent column plays a very crucial role in determining the overall throughput and efficiency of the adsorption process. By means of an order of magnitude analysis, also known as scaling analysis, one can simplify and theoretically investigate this complex heat and mass transfer. The scaling study reveals several interesting physical parameters affecting the overall adsorption phenomenon which can help identify the bottlenecks and thereby improve the adsorption bed design and operation. This chapter will provide a detailed insight into this novel approach. Large temperature jump and large pressure jump imitated adsorption phenomena have been discussed in this chapter. The study has been carried out for silica gel/water vapor pair which is one of the most popular adsorption pairs in the literature; however, the scaling principles introduced in this chapter can be readily extended to other adsorption pairs.

N2 - Adsorption process is the fundamental principle for several advanced technologies like purification and separation technology, refrigeration and heat pumps, thermal and gas storage, desalination, and atmospheric water harvesting. In all these applications the adsorbent material cyclically adsorbs and desorbs the adsorbate for continuous operation. This rate of adsorption depends on several factors such as the properties of the adsorbent, the operating conditions, and the geometry of the adsorption bed. Most adsorption beds use a columnar packing design. Heat and mass transfer occurring within this packed adsorbent column plays a very crucial role in determining the overall throughput and efficiency of the adsorption process. By means of an order of magnitude analysis, also known as scaling analysis, one can simplify and theoretically investigate this complex heat and mass transfer. The scaling study reveals several interesting physical parameters affecting the overall adsorption phenomenon which can help identify the bottlenecks and thereby improve the adsorption bed design and operation. This chapter will provide a detailed insight into this novel approach. Large temperature jump and large pressure jump imitated adsorption phenomena have been discussed in this chapter. The study has been carried out for silica gel/water vapor pair which is one of the most popular adsorption pairs in the literature; however, the scaling principles introduced in this chapter can be readily extended to other adsorption pairs.

AB - Adsorption process is the fundamental principle for several advanced technologies like purification and separation technology, refrigeration and heat pumps, thermal and gas storage, desalination, and atmospheric water harvesting. In all these applications the adsorbent material cyclically adsorbs and desorbs the adsorbate for continuous operation. This rate of adsorption depends on several factors such as the properties of the adsorbent, the operating conditions, and the geometry of the adsorption bed. Most adsorption beds use a columnar packing design. Heat and mass transfer occurring within this packed adsorbent column plays a very crucial role in determining the overall throughput and efficiency of the adsorption process. By means of an order of magnitude analysis, also known as scaling analysis, one can simplify and theoretically investigate this complex heat and mass transfer. The scaling study reveals several interesting physical parameters affecting the overall adsorption phenomenon which can help identify the bottlenecks and thereby improve the adsorption bed design and operation. This chapter will provide a detailed insight into this novel approach. Large temperature jump and large pressure jump imitated adsorption phenomena have been discussed in this chapter. The study has been carried out for silica gel/water vapor pair which is one of the most popular adsorption pairs in the literature; however, the scaling principles introduced in this chapter can be readily extended to other adsorption pairs.

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All around the world, food processing techniques make use of various kinds of treatments to improve the shelf-life of foods. The commonly used thermal treatments are likely to result in deteriorating the sensory as well as nutritional qualities of foods. However, consumers are now demanding for safer and cleaner food without needing to compromise on the quality. Owing to the evolving nature of consumer demands, food technologists and others in the agro-food chain have devised processes to meet these changing demands by considering new non-thermal food processing techniques, which achieve microbiological inactivation in food materials without the application of heat directly. This review provides an appraisal on certain non-thermal food processing technologies with a focus on their operational mechanisms and success in the preservation of numerous kinds of food and offers an outline on the developments in non-thermal food processing techniques used in the food industry to enhance mass transfers. Increase in mass transfer is of industrial interest owing to a reduction in operation time. Use of a faster mass transfer velocity in the process produces multiple benefits, such as an increase in productivity, the preservation of physiological and nutritional value of food components, and a reduction in economic costs. The review demonstrates that techniques such as Pulsed Electric Field, Ultrasonication and Supercritical technology are viable treatments for enhancing mass transfer in the food processing industries.

From early on, food processing technologies have focused on guaranteeing the safety of foodstuffs and prolonging their shelf-life. Recently, authors tempt to develop stainable food systems in optimal food availability, retention, and production (Gould 2011; Hendrickx & Knorr 2002; Bellisle 1998; Knorr 1983, 2003). A wide number of diverse changes have been made to food processing technologies since then, especially within the agro-food industry (Roobab et al. 2018; Pea et al. 2019; Troy et al. 2016; Hernndez-Hernndez et al. 2019). In the agro-food chain, consumers are key. Their demand for fresh and nutritious foods with longer shelf-lives has increased over the years. Owing to the evolving nature of consumer demands, food technologists and others in the agro-food chain have devised processes to meet these changing demands (Hernndez-Hernndez et al. 2019).

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