Etiket Arşivleri: FE 480

Cream Seperation and Homogenization ( Volkan ÖZÇELİK )

The main purpose of the experiment was to separate the cream of raw milk by using Disk-Bowl centrifuge. The main principle of separation depends on density differences between fat and liquid phases. Fat is found as emulsion in the milk. The diameter of the fat globules is significant. By increasing diameter of globules, separation of fat becomes easier. As well we introduced the homogenization that primarily causes disruptions of fat globules into much smaller ones. Consequently it diminishes creaming and may also diminish the tendency of globules to clump or coalesce.

Solid Liquid Extraction ( Yusuf KAYA )

Vegetable oils, sugar, instant coffee, medicines from medicinal plants, etc. are made by processing solid starting material using extraction with liquid solvent(s).

Its initial step is passing the extractant through bulk of the solid in a possibly intimate contact. The contact, however, may be inhibited by air present in interstices between and pores within the pieces to be contacted with the extractant. The air will block penetration of the extractant into some of such cavities. This results in slow and incomplete extraction.

It is therefore desirable to provide a method to remove air blocks in the material to be processed and/or increase the diffusion rates.

High pressure equipment is conventionally used to do this. However, it is expensive, energy-consuming and not always efficient.

The project is aimed at developing a rapid, effective, environmentally friendly and low-cost method to ensure complete extraction of valuable components from solid materials.

Texture and Rheology

ABSTRACT:

Food rheology is the material science of food. Rheology is the science of flow and deformation of matter and describes the interrelation between force, deformation and time. In this experiment, the rheological behavior of solid pekmez with different solid contents (75.4, 71.6 and 67.1 Brixes) was studied in the temperature range of 10, 20 and 30°C using a controlled stress rheometer. Solid pekmez was found to exibit non-Newtonian behavior. However, diluted samples were Newtonian.

THEORY:

Rheology is the study of the deformation and flow of matter. In practice, rheology is principally concerned with extending the "classical" disciplines of elasticity and (Newtonian) fluid mechanics to materials whose mechanical behaviour cannot be described with the classical theories. It is also concerned with establishing predictions for mechanical behaviour (on the continuum mechanical scale) based on the micro- or nanostructure of the material, e.g. the molecular size and architecture of polymers in solution or the particle size distribution in a solid suspension.

Tray Drier ( Kadir DAĞDEVİREN )

The aim of the this experiment was to learn working principles of batch type of tray dryer its application in drying of wet marrow to obtain information about falling rate period, constant rate period, equilibrium moisture content, free moisture content of drying periods, and total drying time was calculated according to results which measured during the experiment on the tray dryer.

Tray Drier ( Özcan NALBANT )

Tray dryers and their developed forms, tunnel dryers are equipments, which found many applications in food operation operations during dehydration of foods. All the drying characteristics of foods can be observed in these equipments.

A typical drying procedure was applied with tray dryer to investigate properties of tray dryers, its advantages or disadvantages, drying kinetics of foods that are dried in tray dryers. For these purposes, equilibrium moisture content, drying rate, mathematical and experimental drying time were calculated with some engineering formulas. Wet pepper was used as sample for this aim.

The result demonstrated that the most important parameters in drying of foods by tray dryer, which affect the time and the quality of food, are temperature and velocity of air, moisture content of food and surface area that is exposed to heated air.

Tubular Heat Exchanger

In the work of Chemical engineering, heat exchanger is an essential part of a unit operation. Double pipe heat exchanger is an excellent example to demonstrate the principle of heat transfer using a simple-structured equipment.

In this experiment we worked on concentric tube heat exchanger. The principle of this device is to cool a hot fluid or to heat a cold fluid by using countercurrent or cocurrent flow. The external surface of the exchanger is insulated to minimize losses in the system, hot water is fed through the iner pipe, with cooling water in the outer annulus.

We worked the concentric heat exchanger with different flow rates and different temperatures to measure the THout, TCin and Tcout values.

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Tubular Heat Exchanger ( Canan ÇİÇEK )

Shell and tube heat exchangers (STHE’s) are apparatuses in which the heat exchange between hotter and colder fluid is done. Fluid flowing through tubes is called – tube fluid, and fluid flowing around tube bundle is called – shell side fluid. Baffles, placed in shell side space, are providing the cross flow direction of shell side fluid and so the more intensive heat exchange between fluids could be realized. Besides, baffles are carriers of tube bundle, which helps them to decrease the deflection in horizontal and vibrations in horizontal and vertical units. STHE’s usually have combined fluid flow, which means that there is parallel in one, and counter flow in other part of the exchanger. These apparatuses are usually denoted as m-n STHE’s, where m is the number of fluid passes through the shell, and n is the number of fluid passes through the tube bundle [9, 14]. If the STHE is with so called “full tube bundle”, the shell side fluid flows through baffle cuts along the tubes. On the shell side, there is not just one stream, beside a main cross-flow stream the four leakage or bypass streams exist as a result of design type: baffle to tubes, baffle to shell and tube bundle to shell gaps (tube – to – baffle hole leakage stream, bundle bypass stream, pass – partition bypass stream and baffle – to – shell leakage stream).

One of STHE manufacturer’s main goals is to improve their exploitation reliability and efficiency. Two approaches in STHE design improving are possible: experimental investigation and numerical investigations. Experimental investigations are very expensive and long lasting, because of shell side complex geometry. Numerical simulations can be used to check the old design and to develop a new more efficient STHE design. Shell side flow is almost always turbulent since tube bundle and baffles are very nice turbulent promoters.

Character of flow around some tube rows in tube bundle is strongly influenced by tube layout (square, rotated square, triangular, rotated triangular, circular).

Character of flow around the tubes has a direct influence on heat exchange between fluids.

Problem is more complex if heat transfer is simultaneous with phase change. Since the detailed measurements of turbulent characteristics of shellside fluid flow are almost impossible, the calculated fields of pressure, velocity, temperature as well as turbulent characteristics are of great significance in explaining very complex thermal and flow processes in STHE’s.

Basically, one can conclude that heat transfer between fluids in STHE’s is highly influenced not only by thermal and flow quantities, such as inlet temperatures and velocities, but also with baffle cut size, baffle spacing, size of inlet and outlet zones and number of baffles.

To investigate influence of mentioned parameters, thermal, flow and geometric, or by other words, to find the “apparatus response” to thermal and fluid quantities and shell side geometry, in steady regime, by experimental and numerical methods, it was necessary to conceive of one compact experimental STHE.