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1. Introduction to the BICOLD WBA range
1.1 Description of the units
The WBA series constitutes a range of air-cooled water chillers designed to meet the
requirements of low and medium capacity air conditioning plants, operating with R410A, a
non-flammable and non-toxic high efficiency refrigerant for optimal energy saving in operation
of the unit.
The entire range is composed of 21 models characterised by the use of scroll compressors
connected in tandem for each circuit, with the exception of the first two sizes of the unit, which
are equipped with just one scroll compressor, by one or two separate refrigerant circuits, and
plate evaporators in brazed AISI stainless steel.
The fans installed are of the axial low-noise type.
The basic version is equipped with exclusively the plate evaporator. The equipment can
consist of a pump, pump with storage tank, dual pump, or dual pump with storage tank.
The pump and storage tank assembly is designated “hydronic unit”.
Control of the chillers is provided by an electronic microprocessor controller.
The refrigerant and hydraulic circuits comply with the PED directive.
Compressors
The compressors are of the hermetic scroll type with orbital scrolls. The rotating scroll is driven
by a two-pole motor cooled by the refrigerant on the suction line. All the compressors are
complete with a crankcase heater to prevent mixing of oil with the refrigerant during stoppages,
electronic thermal protection (if part of the equipment) and thermal overload protection.
All models in the WBA range feature a high pressure unloading function. When a high
condensing temperature is reached (as established by a pressure switch) due to abnormally
high ambient temperature, one compressor stops on each circuit. This results in oversizing of
the condensing coil surface area and dropping of the condensing temperature. Output in these
conditions is slightly higher than 50% of total output but it becomes unnecessary to stop the
unit so that cooling can continue throughout the critical period.
The compressors are filled with polyester oil, which is suitable for use in conjunction with
R410A.
Water-refrigerant plate evaporator
The evaporators are composed of AISI 316 stainless steel brazed plate exchangers. The
exchangers are clad externally with an anticondensation mat made of closed cell expanded
foam.
The exchanger is protected by a series of temperature probes installed on the refrigerant
discharge having an anti-freeze function, and by a pressure switch monitoring the pressure
differential between refrigerant suction and discharge sides.
Air-cooled condenser
The air-cooled condenser is composed of a finned core coil made with copper tubes and
high-efficiency corrugated aluminium fins adequately spaced in such a way as to ensure
optimal heat exchange efficiency. The copper tubes are of sufficient diameter and wall
thickness to withstand the highest R410A resign pressures.
