Transcript No Slide Title

A COMPUTER PACKAGE FOR
DAIRY PLANT REFRIGERATION
SYSTEMS
Q. Tuan Pham
University of New South Wales
Summary

Software has been developed at UNSW
under a DRDC-funded project to simulate
refrigeration systems

We report test results and potential uses
in design, operation and optimisation
Rationale

30 to 50% of electricity in dairy industry is
used in refrigeration

Staff are more concerned with production
than with energy efficiency

Most industrial refrigeration systems can
improve their energy efficiency by about 10 to
15% with negligible capital spending.

Software helps identify possible savings and
inefficiencies
A simple refrigeration system
Generating
cold
Using
cold
Generating
cold
A dairy plant
refrigeration
system
Using
cold
Energy saving 1: Generation of cold

Proper selection of compressors, condensers

Better operation of engineroom (compressor
schedule)

Maintenance of equipment, e.g.
– prevent condenser fouling
– remove noncondensables (air)

Improved control in engineroom, applications

Energy recovery
Energy saving 2: Use of cold

Improved chilling and freezing methods

Better chiller and freezer designs

Shifting loads to reduce peak loads

Eliminating wastages, e.g.
– door infiltration
– excessive fan heat
– poor insulation
Example: Effect of compressor loading on
energy efficiency
Example: non-optimal cooling regime
FAST COOLING:
High energy cost
Quality problems
OVER-DESIGN:
Capital cost $$$
Product
heat load
Optimum
UNDER-DESIGN:
Operational problem
SLOW COOLING
Quality/safety problems
Compliance problems
Cooling/freezing time
Example: Poor airflow distribution in a
chiller
Example: Air infiltration through doors
Simulation software

General purpose simulation software: Aspen
Plus, Hysim...

General purpose refrigeration software:
RADS

Industry-specific refrigeration software:
DRDC-UNSW suite
What software can do

Predicting changes to refrigeration
requirements with
– changes in processing operations
– changes in product type or throughput

Comparing predicted with actual power
consumption - identify wastage

Suggesting alternative schedules for freezers
and chillers to reduce peak power charges
Organisation of programs
User inputs
Outputs:
APPLIC . EXE
PLANT . EXE
ENGROOM . EXE
Spreadsheet
Application heat load
Plant heat load
Power consumption
Graphs, reports
Validation Tests: Objectives

Check that all applications can be modelled

Check that accuracy is acceptable

Check ease of use and robustness
Refrigeration system at a Sydney dairy plant
Compressors
Milk vats
Cold store
Glycol system
Milk intake chiller
Pasteurisers
Silos
UF plant
Heat transfer results for a milk pasteuriser
350
Heat transfer (kW)
300
250
200
Glycol heat transfer (kW)
Milk heat transfer (kW)
150
100
50
0
14:20
14:40
15:00
15:20
15:40
Time (hh:mm)
16:00
16:20
Heat transfer for cream pasteuriser
Site : Dairy Farmers, Lidcombe
Application : Pasteuriser # 7 - Cream, set point 4.0 deg C, data set 3, 22Jan97
T itle : H e a t tr a n s fe r , P a s te u r is e r # 7 - C r e a m
60
50
40
Glycol heat transfer (kW)
Cream heat transfer (kW)
30
20
Heat transfer (kW )
10
0
12:30 12:45 13:00 13:15 13:30 13:45 14:00 14:15 14:30 14:45
T im e (hh:m m )
Total compressor power consumption
Total Compressor Power Consumption for Tue11Feb
.
Measured power
UNDRS max load
UNDRS avg load
Power
0
0:00
2:00
4:00
6:00
8:00
10:00
12:00
Time
14:00
16:00
18:00
20:00
22:00
0:00
Using the Software in Optimisation

Design of new refrigeration plants

Upgrading of plants
–
–
–
–
–
replacement of old equipment
new products
changed flowrates
new processes
changes in schedules
Using the Software in Optimisation (cont)

Checking performance to pinpoint defects

Optimising design and operation
–
–
–
–
Reschedule applications to shift peak load?
Turn off fans and refrigerators temporarily?
One big compressor or several small ones?
One or two stage compression?
Acknowledgments
Dairy Research & Development Corporation
Dairy Process Engineering Center
Dairy Farmers
How about
a Software
Demonstration?
To describe an Application...
Clicking on 1 starts APDATA.EXE
Clicking on ”Help"
brings up...
Clicking on "Create a Chiller"
brings up...
Clicking on ”Page 8" brings up...
To describe a Plant...
Clicking on 3 starts
Double-clicking on a textbox
PLANT.EXE
Clicking
brings on
up “Applications”
the Application window
starts the Applications list
Enter name of file created by APPLIC.EXE here
To describe an Engineroom...
Clicking on p.1 brings up
the General LayoutClicking
windowon 5 starts
ENGROOM.EXE
Clicking “Details on level 1”
brings up...
To describe an Engineroom (cont)...
Clicking
on 5 starts
Clicking
Clicking
on “Compressor
on a textbox
tomodels”
enter
ENGROOM.EXE
brings
models
up the
details...
Compressors
window
To describe an Engineroom (cont)...
Clicking on 5 starts
Click on Operating conditions...
ENGROOM.EXE
Click on a textbox ...
To carry out routine refrigeration calculations ...
Clicking on 8 starts
basic compression cycle
Clicking on 7 starts Basic
Refrigeration Calculations
Clicking here gives results
This presentation can be downloaded from
www.ceic.unsw.edu.au/staff/Tuan_Pham/
(go to bottom of page)
That’s it
folks!
[email protected]