Experiment Report Process & Equipment In Food Technology Iii.pdf

Determine the relationship between the moisture content of the material and the drying time drying curve.. Determine the relationship between the moisture content of the material and the

HA NOI UNIVERSITY OF SCIENCE AND TECHNOLOGY SCHOOL OF BIOLOGY AND FOOD TECHNOLOGY

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EXPERIMENT REPORT

PROCESS & EQUIPMENT IN FOOD TECHNOLOGY III

Instructor: Dr Le Ngoc Cuong

Performed by students: Nguyen Hai Yen

Code ID: 20201334

Class: CTTT- Food Technology 01 – K65

Class code : 726609

Full name: Nguyen Hai Yen

MSSV: 20201334 Grade: 726609

BF2573E: EXPERIMENT HEAT PUMP DRYING

I PURPOSE OF EXPERIMENT

1 Be familiar with and master the process of operating the experimental heat pump drying equipment

2 Determine the relationship between the moisture content of the material and the drying time (drying curve)

3 Determine the relationship between the moisture content of the material and the drying rate (drying rate curve)

I DEVICE AND OPERATION PRINCIPLE

1 Describe a device 2 Air conditioner construction

compressing the vapor from the evaporator pressure to the condenser pressure, pushing it into the condenser

- Hot rig (condenser): is a heat exchange device between a condensing refrigerant

on one side, and a cooling medium on the other side (water or air) The job of the condenser is to release the heat of the condenser to the environment

- Throttle valve: change flow volume, flow velocity increases, pressure decreases

- The evaporator (evaporator): is a heat exchange device between the refrigerant on one side and the medium to be cooled on the other The job of the evaporator is to collect the heat of the cold environment to supply the refrigerant to boil at a low temperature

3 Draw a schematic diagram of the device

Heat pump drying equipment according to the above principle consists of the following components:

I – Calorife, in this calorife there are indoor units to separate moisture and outdoor units to heat TNS

II – Drying chamber 3

III, IV – Inlet and outlet air channels of the drying chamber

V – Technical box, where the compressor, expansion valves, outdoor unit and auxiliary indoor unit are stored

4 Working principle

- Refrigerant in the form of gas through the compressor is compressed to

condensing pressure, then passed through the outdoor heat exchanger for cooling

At that time, the refrigerant will be completely condensed into a liquid form

(exothermic process)

- Next, the liquid in liquid form passes through the throttle valve to regulate the flow

- After that, the refrigerant continues to pass through the evaporator evaporator

- That vapor continues to enter the compressor

The four-stage continuous circulating heat pump cycle:

Stage 1-2: adiabatic compression: the process of compressing refrigerant from low pressure, low temperature to input pressure, high temperature in the compressor

Stage 2 – 3: Isothermal condensate: the refrigerant state changes from superheated steam to boiling water or moisture through the process of discharging heat out by the condenser (outdoor unit)

Stage 3 – 4: Throttle, constant enthalpy: Refrigerant is depressurized as it passes through the throttle, this process does not change the enthalpy of the refrigerant Stage 4 – 1: Isothermal evaporation: Refrigerant state changes from moisture to dry saturated steam or superheated steam through heat recovery by evaporator (indoor unit)

 Advantage:

 The air temperature can only be maintained at ambient temperature or below, so the ability to retain colors, flavors and vitamins is good → suitable for drying materials with poor heat resistance

 It is possible to adjust the temperature of the drying agent depending on the requirements and heat resistance of each product by changing the heat capacity of the condenser

 Energy saving by using both outdoor and indoor unit energy to dry and dehumidify, high heat use efficiency

 The capacity is quite large

 Because the equipment is designed in a circular motion, the raw materials will be

in direct and continuous heat contact, avoiding the phenomenon that some materials are too dry and can become charcoal while others are not can't dry

 The device is designed sustainably and occupies a small area, the structure is simple and compact, so the cleaning and cleaning equipment is simple and convenient

 Environmental protection, safe operation

 Defect:

 The drying time is usually quite long because the difference in water vapor pressure between the drying material and the drying agent is not large

 There must be a solution to defrost after a period of work

II Practice drying vermicelli

TABLE OF EXPERIMENTAL

Time

(minutes

)

Drying chamber temperatur

e ( C)

Drying materia

l weight (g)

Amount of moisture evaporate

d W (g)

Moistu

e mass (g)

Humidi

y of materia

l W(%)

Drying speed (g/min)

1 Weight of moisture in material

In there:

- Weight of moisture at time I, g

- VLS volume at time i, g

- Dry weight, expressed as mass of material after drying (referred to as absolute dry weight), g

2 Amount of moisture evaporating

In there:

, -VLS mass at time i and i+1, g

3 Humidity of Drying material

In there:

- humidity of VLS at time i, %

4 Drying speed

In there:

- time interval between two VLS weighings, minutes

III Graphs and Comment

1 Graph of drying curve

0 5 10 15 20 25 30 35 40

graph shows the dependence material moisture at drying time

Time (minutes)

The moisture content of the material decreases over time

2 Graph of drying rate curve

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6

graph shows the dependence drying rate on drying material moisture

W (%)

The more moisture, the faster the drying speed and vice versa

Full name: Nguyen Hai Yen

MSSV: 20201334 Grade: 726609

BF2573E: EXPERIMENT

EXTRACTION

I Preamble

Extraction is the process of separating one or more solutes from a liquid or solid

by another liquid called a solvent In the content of this experiment, the solid-liquid extraction process will be performed

II Experiment purpose

1 Familiarize yourself with equipment used for extraction: soxhlet, rotary

vacuum evaporator

2 Determine the content of components to be extracted and compare the

efficiency when using different solvents

III Experimental diagram

IV Experimental steps

1 Check the experimental equipment system according to the diagram, install the equipment

2 Prepare measuring tools: Scales, measuring cups , solvents, samples to be extracted

3 Add the extract and solvent to the Soxhlet

4 For cooling water through the condenser tube, turn on the heating (depending on the solvent that has a reasonable heating value)

5 Start calculating extraction time

6 After completing the extraction process, the evaporator is rotated under vacuum to separate the solvent and components to be extracted

7 Record the data in the table

8 After taking all the data, turn off the machine, clean the experimental site, report the experimental results to the instructor

Table 1: Table of experimental results

Solvent is n-hexane

Dry sample mass: 50.1g Solvent amount 60g Extraction temperature 60 0

C

Extraction time 2 hours

Amount of extracted constituents

recovered 16.8g

V Compare test results

=> Result:

- Due to insufficient experimental conditions, only 1 experiment was performed with n-hexane as a solvent

- Based on the theory, it can be predicted that the extraction efficiency in experiment (1) with n-hexane as a solvent will be higher than in experiment (2) with water as a solvent, which means that the time for the experiment will be higher Experiment (2) will take longer

=> Discussion:

- Because the extracted product is oil (non-polar), the use of organic solvents (non-polar) will be easier to dissolve the product than water (polar)

- However, if water is used as a solvent, the oil and residual water will separate

in the recovered product -> easy for product separation

- n-hexane is a volatile compound (boiling point 68.7 degrees Celsius), so the

Full name: Nguyen Hai Yen

MSSV: 20201334 Grade: 726609

BF2573E: EXPERIMENT Exhaust gas recirculating convection drying

I Theory:

Drying is the process of removing some or most of the moisture present in a damp object The drying process is very complicated and unstable, in which many processes occur at the same time such as heat transfer from the drying agent to the drying object, heat conduction in the drying object, evaporation of moisture, and moisture conduction from the inside to the surface surface of the drying object, transferring moisture from the surface of the object to the drying medium The above processes all follow the process of moisture transfer

During the drying process, the moisture content of the dried object continuously changes in a decreasing direction and is divided into 3 stages:

- The first stage: the stage of heating the drying object to the evaporation temperature of the moisture

- The first stage (the stage with constant drying speed): mainly evaporates the free water in the drying object The vapor rising from the surface of the drying object is saturated steam, the heat of vaporization is exactly equal to the heat of vaporization

of free water

- The second stage (phase of drying speed is gradually decreasing): when the internal moisture transmitted to the surface of the drying object is less than the amount of moisture that can be evaporated on the surface of the material This period lasts until the drying material reaches equilibrium moisture content

Drying curve:

The curve representing the change of the moisture content of the dried object with the drying time is called the drying curve: w = f(t) The function graph f(t) depends

on many factors such as the type of bond between the water and the drying material, the shape, size and characteristics of the drying object, the method and the drying mode, but they all have the same general form as illustrated in figure 1

Drying speed curve:

w wA

wc

A B

dw/dt

wB

B

w

f(w) is the line segment AB parallel to the horizontal axis The representation of the second stage of the drying process has a complex shape, depending on the structure of the drying material and the type of bond between the moisture and the dry matter in the dryer

II Experiment purpose:

- Be familiar with and master the operating process of convection drying experiment equipment with exhaust gas recirculation

- Determine the relationship between the moisture content of the material and the drying time (drying curve)

- Determine the relationship between the drying speed and the moisture content of the material (drying rate curve)

III Experimental diagram and working principle of experimental equipment: 11

   

On

12

10

7

6

5

4

1 Scales

2 Drying material

3 Drying chamber

4 Air intake door

5.Fan

6 TNS outlet

7 Caloriphe

8 Control cabinet

9 Flanges

10 Bracket

11 Total Atomat

12 Control switch

Rules of work:

The outside air is sucked in by fan 5 through door 4 and then heated in an electric caloriphe 7 Air temperature control thanks to the contact thermometer system The wet material is placed in trays placed in a frame of the drying chamber The frame is hung on the weighing pan 1 Observe the change in the mass of the dried material on the needle of the balance Adjust the amount of exhaust air thanks to the screened door 6

- Step 3 Observe and check the experimental system according to the diagram

- Step 4 Open the fan and close the heat transfer bridge to increase the caloriphe heat

- Step 5 Wait until the drying temperature (drying agent) is stable (dry at a certain temperature, then adjust the contact thermometer) before adding the material and reading the reading on the scale

- Step 6 Read and record the reading on the scale every 5 minutes for moisture evaporation Continue doing this until the reading on the balance does not change after 3 measurements, then stop the experiment

- Step 7 Turn off the calorific circuit breaker, wait 10 minutes and then turn off the fan Take out the dried material to observe and weigh the material Record the data obtained and report to the instructor

- Step 8 Clean up the experiment place before leaving

V Calculation

1 Initial amount of moisture in the material:

g = G - G k (g)

G k - Absolute mass of dry material, g

2 The amount of moisture evaporated:

W i = Gi - G i-1 , (g)

Gi , G i-1 :To bemass of material for time i and i-1

3 The amount of moisture contained in the material:

W' = g - (g)

4 Material moisture:

W = W'.100 / G , (%)

VI Table of experimental data and calculation results:

No

Experimental data table Calculation results

Time

t(min)

Drying chamber temperat ure ( 0 C)

Scale indicato

r G (g)

Amount of moisture evaporat ing

W i (g)

Amount of moisture

in the drying material W' (g)

Moisture

of drying material

W (%)

Drying speed



Fd dW

(g/min)

VII Report:

1 Graph of drying curve:

0 5 10 15 20 25 30 35 40

The drying curve graph shows the dependence

material moisture at drying time

t (minutes)

Comments :

- The moisture content of the drying material decreases with time.

- Towards the end of the drying period, the drying speed decreases due to the decrease in free moisture, increased binding moisture

- The final amount of moisture in the drying material is zero compared with the original dry material (relative only) In fact, the material is still moist after drying, especially the bonding moisture

- If drying continues for a long time, the amount of moisture will still decrease, but the quality of the material will be changed (possibly burning)

3 Graph of drying speed curve:

0 5 10 15 20 25 30 35 40 0

0 0 0 0 0.01 0.01

The drying curve graph shows the dependence drying rate and drying material moisture

W (%)

Comment:

- The higher the humidity, the faster the drying speed and vice versa

- The drying speed in the first stage increases rapidly and stabilizes in the middle, then gradually decreases at the end of the period Because in the early stage, the amount of free moisture is large and there is a large amount of surface moisture, so the moisture drainage is quick and easy, the moisture drainage rate is reduced due

to the decrease in free moisture, and the bonding moisture is increased