HAWKES BAY REFRIGERATION Energy Efficiency And Reliable
Refrigeration Presented By Scott Klem
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INTRODUCTION Scott Klem Local Refrigeration Service Provider
Hawke's Bay Refrigeration (2005) Limited is a Hawke's Bay owned and
operated company specializing in all aspects of domestic,
commercial and industrial refrigeration. Hawkes Bay Refrigeration
has been in the Refrigeration, Heating Ventilation and Air
Conditioning (HVAC) industry since 1992. We design and install
refrigeration and air conditioning systems, and provide maintenance
and service contracts to suit our clients requirements. Our company
provides for a wide range of industries, from office and home air
conditioning, to orchard cool stores, controlled atmosphere rooms,
meat processing plants and winery refrigeration systems. Like
WorleyParsons we dont have any allegiance to any particular brand
Carried out Massey University Courses on Cost Effective
Refrigeration
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IMPROVE EFFICIENCY OF YOUR EXISTING SYSTEM Typically the
reasons for inefficient refrigeration system performance are: poor
design, poor control and poor maintenance. The latter two are
relatively easy to fix, while the first reason is likely to require
capital investment. To improve the efficiency of your existing
plant without spending large amounts of capital, we recommend:
Ensuring a whole system approach is used Regular preventative
maintenance Glycol as a cooling medium Staff are familiar and
trained with the operation of the plant Variable speed drives on
condensor, evaporator fan motors and pumps Electronic expansion
valves Optimize your suction and discharge pressures
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ENSURING A WHOLE SYSTEM APPROACH IS USED We recommend when
looking at your system that you take in consideration all aspects.
For many businesses, refrigeration systems consume large amounts of
electricity, thereby contributing greatly to operating costs.
Improvements to technical aspects of operations have the potential
to reduce energy use by up to 40%, whilst simple improvements in
operational practices can reduce energy use by 15%.
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SYSTEM CONSIDERATIONS Ensure a whole-system approach is used.
Design for year-round efficiency. Avoid heat gain in the system by
using ambient pre-cooling of product, adequate insulation, shading,
minimising air infiltration and so on. Design for part-load
performance using VSDs on compressors or efficient control of
multiple compressors. Use of refrigerant storage in the system to
meet demand peaks. Opportunities for heat recovery. Layout of
product within the cooled space to optimise exposure of product to
cooled air. Pipe layout to minimise run lengths and ensure product
flows are smooth.
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REGULAR PREVENTATIVE MAINTENANCE We recommend that you get your
system fully checked and cleaned at the start of each season and
then either quarterly or 6 monthly checks depending on your
equipment. These checks should include the following: Cleaning of
condensor coils Cleaning of evaporator coils Replacing noisy fan
motor bearings Refrigeration leaks Glycol percentage checks Glycol
is clean and free of air Door seals are in good condition with no
gaps Room insulation Check for moisture or ice forming on the
outside of cool store Clean Glycol strainers Compressor sets are
efficient and effective Check suction and discharge pressures are
set correctly
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STAFF ARE FAMILIAR AND TRAINED WITH THE OPERATION OF PLANT Your
onsite staff need to be trained and familiar with the operation of
your plant as this varies throughout the year. Small plant
adjustments to suction pressures, discharge pressures and defrost
setting can save up to 15% of your energy costs. This is especially
important during low peak loadings.
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VARIABLE SPEED DRIVES ON CONDENSOR, EVAPORATOR FAN MOTORS AND
PUMPS Variable speed drives should be considered when your plant is
not running at its full load. A general rule of thumb for fans is
that if you run your fan at 70% capacity you can save 20% of your
energy cost without affecting performance of the system when at
part load. IE if you run your fans at 35hz you can save 20% power
costs. Also VSDs on pumps can be a great energy saver when the
pumps are not at full load. We recently had a system were we had 4
x 11 kw Glycol pumps constantly running. We installed a pressure
transducer and VSD on the lead pump and cycled the other pumps on
and off as required. This controlled the system pressure accurately
and allowed the other 3 pumps to cycle off. The power savings were
approximately $70 per day.
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ELECTRONIC EXPANSION VALVES One of the main advantages in using
EXV technology is the energy saving achievable due to improved
efficiency of the refrigeration cycle. The possibility to operate
at low condensing pressures, as well as precise superheat control,
allow considerable energy saving: the advantages have been proven
and validated in the field, in both refrigeration and air-
conditioning applications, and guarantee extremely short payback
times compared to standard mechanical technology.
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GLYCOL AS A COOLING MEDIUM Glycol needs to be clean Free of air
and contaminants Correct percentage - Types of glycol - Mono
ethylene - Mono propylene - Specific heat capacity (The amount of
heat required to raise a kilogram of any substance by 1C) Correct
flow rates
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REMOVING AIR FROM GLYCOL SYSTEM IS A PRIORITY TO: Save Money:
lower energy bill less maintenance longer lifetime Optimum Water
Circulation Protect Valuable Components Improved Heat Transfer
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DEAERATION Free air (Automatic air vent) Microbubbles
(Microbubble Separator) Dissolved Air (Pressure step
deaerator)
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CONCLUSION In conclusion I believe the most important aspects
to make your plant more energy efficient are: Regular plant
maintenance Optimising your current temperature settings,
compressor suction and discharge setting Investing in VSD control
for part loads Ensuring your glycol system is clean and free of
air.