Etiket Arşivleri: FE 480

Losses In Piping Systems ( M. Ali KARADAĞ )

FE 480 FOOD ENGINEERING OPRATION LABORATORY

LOSSES IN PIPING SYSTEMS

MEHMET ALİ KARADAĞ
HAKAN MAVİŞ
ALİ SÖNMEZ

INTRODUCTION

One of the most basic calculations performed by any process engineer, whether in design or in the plant, is line sizing and pipeline pressure loss.  Typically known are the flow rate, temperature and corresponding viscosity and specific gravity of the fluid that will flow
through the pipe.  These properties are spreadsheet along with some pipe physical data (pipe schedule and roughness factor) and out pops a series of line sizes with associated Reynolds Number, velocity, friction factor and pressure drop per linear dimension.  The pipe size is then selected based on a compromise between the velocity and the pressure drop.  With the line now sized and the pressure drop per linear dimension determined, the pressure loss from the inlet to the outlet of the pipe can be calculated

Discussion

Our aim was to measure frictional pressure losses in pipes valves fittings and simple flow measuring devices. To design or specify a piping system the pressure drop must be calculated very well.and the pressure drop is caused by head loss and also the pressure drop is affected by friction factor. At this point major losses and minor losses must be considered.because they affect the head loss.therefore they can affect the pressure drop

In summary major losses due to viscous resistance extending throught the total length of circuit.minor losses due to localized effects such as valves elbows sudden changes in area of flow bends and fittings of all types.so the overall heat loss is a combination of both this categorized.

The maximum water pressure avilable to supply each fixture depends on the water service pressure at the point where the building distrubution system begins.this pressure depends either on local pressure limits set by local codes pressure designed by the system designer or on a combination of this.In any case it soudnt higher than 80 psi

However the entire water service pressure is not available at each fixture due to pressure losses inherent to the system. The pressure losses include losses in flow through the water meter static losses in lifting water to higher elevations in the system and friction losses encountered in flow through piping fittings valves equipments. Due to that point, the calculations and graps were took place in order to understand losses in piping system.

Supercritical CO2 Extraction System Milk Fat Fractination ( Prof. Dr. Ahmet KAYA )

FE 480-Food Operations Laboratory
Dr. A. Kaya

SUPERCRITICAL CO 2 EXTRACTION SYSTEM MILK FAT FRACTIONATION

Introduction

Many technologies have been developed for the separation and fractionation of different food compounds in the food industry. Conventional processes such as crystallization, filtration, distillation or precipitation are being substituted by new processes that use membranes or supercritical fluids. Supercritical fluid extraction (SFE) is a separation process where the substances are dissolved in a fluid which is able to modify its dissolving power under specific conditions above their critical temperature and pressure (supercritical region). The properties of a supercritical fluid are used to extract selectively a specific compound or to fractionate mixtures by changing the temperature and pressure without any phase change. A supercritical fluid is a liquid or a gas at atmospheric conditions which is operational when compressed above its critical pressure (50–250 bar) and heated above its critical temperature (20–60 o C). The most important property of these fluids is the dissolving power in their supercritical region. In the phase diagram for a pure compound, it is possible to distinguish the three material states: solid, liquid and vapor. There are also two important points: the triple point and the critical point. The triple point is the point at which the three states coexist. The critical point lies at the end of vaporisation curve, where the gas and liquid phase merge to form a single homogeneous fluid phase, and beyond this point is the supercritical fluid region. A supercritical fluid exhibits physicochemical properties between those of a gas and a liquid, and has the capacity to dissolve compounds that may only dissolve poorly or not at all in the gas or liquid state. The dissolving power of a supercritical fluid varies with density, which can be as high as a liquid or as low as a gas depending on small changes in pressure and/or in temperature. These properties of supercritical fluids provide a good extraction of the compounds due to their high dissolving power at high densities, and consequently a good fractionation and separation of the compound from the fluid (at lower densities) by reducing the pressure or changing the temperature in a separator. Another important factor is the penetrating power based in the high mass transfer rate of the solutes into the fluid. The low viscosity and high diffusivity of the supercritical fluid enhance this property allowing an efficient extraction of the compounds from the raw material. Supercritical extraction is not widely used yet, but as new technologies are coming there are more and more viewpoints that could justify it, as high purity, residual solvent content
and environment protection. The basic principle of SFE is that when the feed material is contacted with a supercritical fluid than the volatile substances will partition into the supercritical phase. After the dissolution of soluble material the supercritical fluid (SCF) containing the dissolved substances is removed from the feed material. The extracted component is then completely separated from the SCF by means of a temperature and/or pressure change. The SCF is then  may be recompressed to the extraction conditions and
recycled. Some of the advantages and disadvantages of SCFs compared to conventional liquid solvents for separations:

Advantages

 Dissolving power of the SCF is controlled by pressure and/or temperature

 SCF is easily recoverable from the extract due to its volatility

 Non-toxic solvents leave no harmful residue

 High boiling are extracted at relatively low temperatures

 Separations not possible by more traditional processes can sometimes be effected

 Thermally labile compounds can be extracted with minimal damage as low temperatures can be employed by the extraction

Disadvantages

 Elevated pressure required

 Compression of solvent requires elaborate recycling measures to reduce energy costs

 High capital investment for equipment

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.