Volume-2 - Delhi Metro Rail Corporation

2.2 MULTI PURPOSE CHILLER
TENDER NO. DMRC/ELECT./IT&PD/ILBS/HVAC-LV-FF-02
Chillers should be of High efficiency series with elevated total efficiency rates (TER). The chiller
should be capable of working at Cooling Mode to generate only cooling, Heating mode to
generate only heating and both cooling and Heating Mode to generate cooling and heating
simultaneously.
The chillers should have auto defrosting system that is able to optimize the defrosting time with
improvement of the total efficiency.
.
Multi-purpose units should work with automatic mode switch suitable for outdoor installation on
four-pipe plants with capability to work also with a 2 pipe system or with separate 4/2 pipe
cooling/heating , and separate 2 pipe heating system. The unit should be supplied with anti-freeze oil
and refrigerant and has been factory tested. On-site installation will just involve making connections
to the mains power and water supplies. Unit should be factory charged with R410a / 407c / 134a
refrigerant.
UNIT COMPOSITION
Supporting frame should have base and frame in thick hot-galvanised shaped sheet steel. All parts
should be polyesters-painted.
Compressor
Semi-hermetic screw compressors should be designed for high efficiency both at full and partial load. The
bearings should be provided along the rotor axis in a separate chamber isolated from the compression chamber
are made in carbon steel. Each compressor should have provided with an inlet for refrigerant injection (for the
extension of operating limits) and the use of the economiser (for the output capacity and efficiency´s
increase). Each compressor should be fitted with manual-reset motor thermal protection. A check valve should
be fitted on the refrigerant delivery line to prevent the rotors from reversing after stopping.
PRODUCTION OF JUST CHILLED WATER
The unit should work like a simple chiller and therefore discharges the excess heat from inside the
building (condensation heat) to the atmosphere through the Air finned tube heat exchanger.
The water is cooled in a water shell and tube heat exchanger. (Evaporator).
PRODUCTION OF JUST HOT WATER
In this case, the unit should work exactly like a heat pump which channels the heat of the external
atmosphere through an Air finned coil (evaporator) in order to heat the water sent to the inside of the
building through a water shell and tube heat exchanger (condenser). The hot water should be
produced in a heat exchanger ( called a heat recovery shell and tube exchanger) and not a shell and
tube evaporator. This is necessary in order to keep the hot and cold sections separate as required by a
four-tube systems.
COMBINED PRODUCTION OF HOT AND CHILLED WATER
The unit should be capable of providing Hot & Cold water SIMULTANEOUSLY in any proportion,
irrespective of the individual Heating & Cooling load at any given point of time. If the user’s
PAGE No 19 of 204 Nov.2011