To be energyefficient,
precision air conditioning units must provide almost exclusively
sensible cooling, because in most cases the heat load is entirely
sensible. However, they must also be capable of latent cooling if
and when it is required.
A high airflow rate is a prerequisite for an efficient system and to
prevent temperature swings.
Uniflair engineers set out to achieve this objective, without sacrificing
the extremely compact dimensions or the low fan power consumption of
the units, by using state-of-the-art software and sophisticated mathematical
modelling techniques, followed by lab testing of the finished components.
The fluid dynamics at these high flow rates have then been finally
perfected in an extensive series of laboratory tests on complete Leonardo
units.
The Leonardo range gives building services engineers considerable design
freedom with a choice of two main fan types:
Centrifugal fans with forward curved blades
Centrifugal fans with backward curved blades.
Versions
Available.
Another important characteristic
of Leonardo units is that the dehumidification function operates
only when actually required. This is achieved without a reduction
in the air flow rate, ensuring continuous and uniform air distribution
in the space and avoiding any sudden variations in discharge air
temperature.
dxa series air-cooled direct expansion units.
Air-cooled direct expansion units extract heat from the room and
transfer it to the outside air using air-cooled refrigerant heat
exchangers (condensers).
Once installed, the room unit and external condenser form an autonomous
sealed circuit.
The Uniflair remote condensers used with Leonardo units include precise
electronic fan-speed condensing pressure control to ensure trouble-free
operation of the unit throughout the year under a very wide range
of external air temperatures.
Special attention has been paid to the acoustic design of the condensers
to minimise noise levels.
A wide range of combinations is available to meet different site
requirements.
dxw series water-cooled direct expansion units.
In water cooled units the heat extracted from the room is transferred
to water via stainless steel brazed-plate heat exchangers within
the unit. The cooling water may be fed from the mains supply (where
permitted), a cooling tower or a well (ie: open circuit), or circulated
in a closed loop cooled by external dry-coolers.
In the latter case an anti-freeze mixture of water and ethylene glycol
is normally used.
Water-cooled units have the advantage that the refrigerant circuits
are pre-charged and sealed in the factory.
This makes system installation extremely simple, eliminating the
need for any site-installed refrigerant pipework.
cw chilled water units.
cw units use the availability of chilled water to control room conditions.
This version of Leonardo has a relatively simple construction and
outstanding reliability.
The Uniguard microprocessor controls the modulating action of the
three-way (or optional 2-way) chilled water valve to give accurate
capacity control. Careful sizing of the heat exchanger coils yields
a high sensible-to-total cooling ratio under most operating conditions
at the appropriate chilled water temperatures.
Twin-Cool
units.
Leonardo
Twin-Cool units are fitted with two completely independent cooling
circuits:
- Chilled water
- Air-cooled or water-cooled direct expansion.
This unit is normally used where an installation has a chilled water
source which cannot be relied on to guarantee continuous service.
Function priority is given to the chilled water circuit, with the
microprocessor control automatically starting the direct expansion
circuit if the chilled water supply fails or if the water is not
cold enough to dissipate the entire heat load.
Twin-Cool units therefore provide a very high level of security and
ensure continuous system operation.
Energy-saving units.
Leonardo Energy-Saving units represent the ultimate energyefficient
solution in cool or temperate climates. The operating principle exploits
the “free cooling” effect available when the outside
air temperature is lower than that in the conditioned space: the
lower the outside temperature, the greater is the energy saving.
The sophisticated Uniguard microprocessor control manages operation
of the unit automatically in three different situations. In summer
the unit operates as a normal closed circuit glycol-cooled system
(diagram A). As the external temperature falls, the coolant can be
used directly for the free cooling of the air. In this case the coolant
is circulated in the coil inside the unit (diagram B) and both the
refrigerant circuit and the glycol circuit contribute to cooling,
thus reducing the energy used by the compressor. If the outside temperature
falls further to a level
where the coolant can dissipate the entire heat load from the room
then the refrigerant circuit is shut down completely and the unit
functions as a traditional chilled water unit with modulating valve
(diagram C).
With this technology Leonardo Energy-Saving units provide significant
reductions in operating costs and payback periods.
Constant temperature and humidity.
Modern electronic equipment may be able to operate under a relatively
wide range of conditions but its longevity and reliability are greatly
enhanced under constant conditions of temperature and humidity. All
the heat produced must be removed to prevent catastrophic increases
in temperature. Although electronic equipment produces only sensible
heat, humidity must be monitored to prevent possible system faults.
Leonardo air conditioning units are specifically designed to maintain
temperature and humidity conditions within extremely tight tolerances,
even when the heat load fluctuates.
.
High
energy efficiency
The minimising of operating
costs in high-tech installations is becoming evermore imperative
in a competitive marketplace.
Combined with the ever-greater emphasis on respect for the environment,
this means that high energy-efficiency is now a key factor in precision
air conditioning.
Leonardo units have been designed with this objective at the top
of the agenda.
Their low energy consumption is the result of an exhaustive analysis
covering everything from the choice of components to the constant
refinement of design solutions:
•
Scroll compressors are used throughout the range
•
High efficiency fans, whether with forward-curved or backward-curved
blades (higher airflow for the same power consumption)
•
Optimised air flow pattern to reduce pressure drops both internally
and at the discharge
•
Energy Saving versions which maximise free-cooling time and thus
minimise compressor operation.
•
Effective integration in mixed systems that use high capacity chillers
with free-cooling coils designed for these applications
•
Accurate heat-exchanger sizing
•
Extreme care in eliminating flow restrictions and minimising friction
losses in all fluid circuits
•
Control strategies ensure optimum operation of system components
under all operating conditions
•
Control software that operates energy-saving cycles to maximum effect.
Compact dimensions.
Uniflair has always paid special attention to the dimensions of its
equipment and to the logistics of its handling, installation and
accessibility.
Given the very high cost of space in high-tech environments, it is
vital not only to have precision air conditioning with the smallest
possible footprint but that the same equipment must also have full
frontal component access to enable units to be installed side by
side with each other, or with other equipment.
Leonardo units represent the industry benchmark in this respect -
particularly compact, low-weight, quick and simple to install, and
easy to manoeuvre even in confined spaces.
Handling
and installation.
Leonardo air conditioning units are
designed for maximum ease of on-site handling and installation.
Compact dimensions enable the units to be taken through standard
doorways and carried in most goods lifts. A set of wheels specially
designed for the Leonardo range enable units to be removed from the
pallet, moved easily and safely, and then accurately positioned.
Refrigerant and water connections to the unit do not require on-site
brazing or welding, and all components that need to be adjusted or
checked during commissioning are readily accessible.
Maintenance.
The ease of maintenance of Leonardo
units is a further fundamental factor in reducing operating costs
and avoiding downtime. All normal maintenance operations can be carried
out from the front of the unit and the front panels can be opened
without the need for special tools.
A push-button catch ensures easy access to the controls compartment
while the cover of the electrical panel inside is fitted with a safety
interlocked mains isolator in compliance with safety regulations.
Respect
for the environment.
Every aspect of the Leonardo series
has been evaluated for its environmental impact during the process
of design and development, a philosophy reflected across the whole
Uniflair product range. In addition to minimising the indirect global
warming potential by efficient use of energy, this also means the
use of recyclable materials and strictly eco-compatible refrigerants.
Leonardo units are also particularly quiet, thus contributing to
an environment suited not only to equipment but also to people.
The same applies to the range of air-cooled condensers and dry-coolers,
because low external noise levels can be equally important in many
applications, particularly for night-time operation.
Function
of Leonardo
1 Scroll compressor.
2 Brazed plate condenser.
3 Electrode boiler humidifier.
4 Modulating drive three ways valve for Energy Saving unit.
5 Backward
blades centrifugal fan.
6 Electric heaters with safety thermostat.
7 Refrigerant circuit liquid
receiver.
8 Condensing pressare
regulation valve.
9 Filter-dryer refrigerant circuit.
10Expansion valve.
11 Liquid sight glass.
12 Refrigerant circuit
high pressure switch.
13 Refrigerant circuit
low pressure switch.
14 Air filter with metallic
frame.
15 Temperature and humidity
sensor.
16 Microprocessor control board cabinet.
17 Command and control
panel.
18 Graphic user
terminal Uniguard UG10.
19 Electric cabinet door lock.
20 Cooling coil.
Accessories
Downflow units.
1 Hot water reheat coil.
2 Hot gas reheat coil (direct expansion units only).
3 Water flow regulation valve
(water cooled units only).
4 Electrode
boiler humidifier with cleanable electrodes.
5 Double skin panels.
6 Suction plenum with
standard insulation.
7 Suction plenum with
sound proof buffles.
8 Suction
plenum with air filters up to EU8 efficiency.
9 Suction plenum with
motorized damper.
10 Height adjustable baseframe.
11 Floor
stand with standard insulation and front discharge.
12 Floor stand with
air filters up to EU8 efficiency.
13 Floor stand with motorized
damper.
14 Baseframe with motorized
damper.
15 Baseframe with discharge
baffle.
16 Fire detector.
17 Smoke detector.
18 Water leak detector.
19 Fresh air filter.
20 Air temperature/humidity
external sensors.
Upflow
units.
1 Hot water reheat coil.
2 Hot gas reheat coil (direct expansion units only).
3 Water flow regulation valve
(water cooled units only).
4 Electrode
boiler humidifier with cleanable electrodes.
5 Double skin panels.
6 Discharge plenum with standard
insulation.
7 Front discharge
plenum with grille and standard insulation.
8 Discharge plenum with sound
proof buffles.
9 Discharge plenum
with air filters up to EU8 efficiency.
10 Discharge overpressure damper.
11 Height adjustable baseframe.
12 Floor stand with standard
insulation.
13 Floor stand with
air filters up to EU8 efficiency.
14 Fire detector.
15 Smoke detector.
16 Water leak detector.
17 Fresh air filter.
18 Air temperature/humidity
external sensors. |
