Presentation of Refrigeration Simulation

A Presentation on

STUDY OF A REFRIGERATION UNIT

Prepared ByMuhammad Shafiul Munir

Student ID: 0902049A2 (Group 04)

Partner’s: 0902046090204709020480902050

Department of Chemical Engineering, BUETDate: 05.06.2013

Presentation at a Glance

What is Refrigeration

Vapour- Compression Refrigeration Cycle

Why we are so concerned about Refrigeration

Experimental Set-up

Schematic Diagram

Graphs

Result

Thermodynamic Significance of Refrigeration

Conclusion

What is Refrigeration ??

Transfer of heat from a Lower Temparature region from a higher one

The device that works cyclically to perform this job is Refrigerator

The working fluid used in refrigerator is called refrigerant.

Ideal Vapour Compression Cycle

1. (1-2) Isentropic Compression in a Compressor

2. (2-3) Constant Pressure Heat Rejection in a Condenser

3. (3-4) Throttling in an expansion device

4. (4-1) Constant Pressure Heat Absorption in an Evaporator

The Actual Vapour Comoression Cycle

Irreversibility

• Fluid Friction

(Pressure Drop)

• Heat Transfer

Why Study Refrigeration ??

Food Preservation

Gas Liquefaction

Used in Oil

Refineries

Chemical Plants

Petro-Chemical

Plants

Why Study Refrigeration (Continued) ??

Steel and Cutlury

Meats, Fish and

Poultry

Dairy Industry

Transporting

Temperature

Sensetive foodstuffs

or pharmaceuticals.

Experimental System

Schematic Diagram

Calculation Process

1. Rate of Heat Transfer in both Evaporator and Condenser-

Q= ṁCp(Δt)

2. Overall Heat Transfer Co-efficient for both Evaporator and

Condenser-

U= Q/ AΔt LMTD

3. Compressor Pressure Ratio-

P= Pc/Pe

Results

Observation

Number

Rate of Heat

Transfer to

Water in

Evaporator,

Qe (W)

Rate of

Heat

Transfer to

Water in

Condenser,

Qc (W)

Overall Heat

Transfer

Coefficient,

Ue(W/m2.0C)

Over all Heat

Transfer

Coefficient,

Uc(W/m2.0C)

Compressor

Pressure

Ratio,

( Pc / Pe)

01 20.5 41.8 52.25 375.8 10.77

02 167.2 41.8 435.78 529.7 10.49

03 12.54 83.6 31.75 1435.4 10.45

04 83.6 125.4 227.37 1810.9 11.41

05 41.8 125.4 104.5 1810.9 11.55

Graph 01: Saturation Pressure Vs. Saturation Temperature

0

50

100

150

200

250

300

0 20 40

Satu

rati

on

Pre

ssu

re

Saturation Temperature

Evaporator

Condenser

Actual Experimental

Graph 02: Heat Transfer Rate Vs. Condensing Temperature

0

20

40

60

80

100

120

140

160

180

20 25 30

He

at T

ran

sfe

r R

ate

Condensing Temperature

Heat Transfer Rate Vs. Condensing Temperature

Heat TransferRateEvaporator

Heat TransferRateCondenser

Actual Experimental

Graph 03: Heat Transfer Rate Vs. Compressor Pressure Ratio

0

20

40

60

80

100

120

140

160

180

10 11 12

He

at T

ran

sfe

r R

ate

Compressor Pressure Ratio

Heat Transfer Rate Vs. Compressor Pressure Ratio

HeatTransferRateEvaporator

HeatTransferRateCondenser

ExperimentalActual

Refrigeration- Thermodynamic Point of View

Refrigeration operates on a true Thermodynamic cycle

It Involves-

Nucleate Boiling and Filmwise Condensation

Steady Flow processes like throttling, compression and Heat Exchange.

Flow Control

Conclusion

In this experiment our main objective was to study

refrigeration unit.

After the Experiment it is quite clear that the

objectives were quite fulfilled.

Performance of refrigeration can be increased using-

Cascade Refrigeration System

Multistage Refrigeration System

Questions ???

Cascade Refrigeration

Reversed Carnot Cycle

Multistage Compression Refrigeration System