Durban mall upgrades to highly-efficient air conditioning systemJason Siddall
The popular upmarket Pavilion Shopping Centre in Durban is currently in the process of upgrading its air conditioning system, by replacing its existing units with energy-efficient Carrier 19XRV centrifugal chillers.
DURBAN, South Africa, July 8, 2015 — Phase 1 of the air conditioning upgrade involves the installation of three Carrier19XRV centrifugal chillers, which boast a total cooling capacity of 10 050 kW.
Leading shopping Centre investor Pareto, which owns the Pavilion, procured the new air-conditioning system from an environmentally sustainable perspective. “As a company committed to the basic principles of water conservation and energy and operational efficiency in all our centres, we were satisfied that the system fulfilled our requirements,” says Mark MacKaizer, The Asset Manager at The Pavilion Shopping Centre.
“We were also happy with the price, and with the guarantee and maintenance support provided by the suppliers. We were advised by mechanical engineers that these chillers have been used at various sites, without any defects and with low operating costs. The system sounds technically promising and we look forward to seeing how this new technology delivers at the Pavilion,” he adds.
The advanced Carrier 19XRV chillers provide exceptional value, with energy efficiency ratio (EER) levels as high as 6.8, by utilising proven technology designed specifically for chlorine-free refrigerants (R134a). The 19XRV units consist of a single stage aerodynamic impeller, tunnel diffusers based on aircraft engine technology, and are motor-cooled by refrigerant gas injection.
The compressors are controlled using a unit-mounted variable frequency drive to maximise the chillers’ energy efficiency. This is used in conjunction with high-efficiency evaporator and condenser tubes, an expansion sub-cooler integrated into the condenser, and patented float valve technology for optimised sub-cooling and refrigerant level in the evaporator.
The single-stage hermetic compressor increases product reliability by eliminating the additional moving parts associated with multiple stage machines, such as additional guide vanes and complex economisers.
The Carrier 19XRV chillers are also equipped with a compressor variable frequency system. By changing the compressor operating mode, this system considerably reduces power consumption based on the motor’s rotational speed.
In addition, the variable frequency drive control box is cooled by refrigerant, thereby minimising size and ensuring optimal component cooling for an extended operating life. This concept makes water cooling unnecessary, and eliminates the associated maintenance cost and power consumption of the water pump.
Capacity control is achieved by means of variable inlet guide vanes located at the impeller inlet. Load modulation ranges from 100 percent to 15 percent of the full compressor load, under nominal ARI conditions.
The guide vanes are precisely positioned by a proportional integral derivative (PID) control algorithm to ensure precise and quick control of desired chilled water temperature, without hunting or overshooting the set point.
With the variable frequency drive, the compressor speed is regulated by the control of the voltage-frequency values applied to the motor. The voltage applied, generated by pulse width modulation, is proportional to the frequency.
The calculation of the water temperature parameter deviation measures results in an adjustment of the machine capacity through a simultaneous and co-ordinated action on guide vane opening and compressor speed.
The 19XRV centrifugal chillers were supplied to the mall upgrade project by AHI Carrier South Africa (Pty) Ltd, and were sourced from Carrier’s factory situated in Charlotte, USA.
Carrier is a part of UTC Building & Industrial Systems, a unit of United Technologies Corp. (NYSE: UTX).