More than 60 per cent of primary energy use in Asia is consumed by the building sector, with the majority directed at air conditioning, heating, ventilation and lighting.
Regulations are being used to tackle the problem and new standards are also being set in the design and control of air conditioning systems.
Significant opportunities for greater efficiency also exist in the chiller market, where best in class technologies are increasingly being adopted. According to research from Emerson Climate Technologies, the Asia Pacific has the largest chiller market in the world, comprising 47 per cent of the world’s total.
For manufacturers seeking greater efficiency, the focus is on efficiency at full-load and part-load conditions, the equipment applied and maintenance costs, and the responsible use of refrigerant for environmental protection.
As a result, Emerson says, manufacturers are designing chillers for high efficiency, not only at nominal rating conditions but for operational conditions all year round.
The load of a central air conditioning system varies according to external air temperature, building activity level and solar radiation in relation to the building’s orientation and ventilation.
The chiller’s performance also depends on the building load requirements and it varies as a function of the ambient temperature.
Applied cost is another factor for chiller efficiency. Critical chiller components that affect efficiency and applied cost include heat exchangers and compressors.
Emerson says one key parameter that influences heat exchanger and compressor selection is the choice of refrigerant.
While R22 is still commonly used, the chiller industry is looking to HFC-based alternatives in accordance with the Montreal Protocol.
Many chiller manufacturers are looking to R410A to lower refrigerant charge. The refrigerant also allows manufacturers to reduce the size of the heat exchanger while still maintaining the same system efficiency. Another option is keeping the same size heat exchanger for increased system efficiency.
More efficient technologies available for compressors include reciprocating semi-hermetic compressors, scroll hermetic compressors, and screw semi-hermetic compressors.
Many manufacturers have selected R410A large commercial scroll compressors to strike a balance between seasonal efficiency, reliability, ease of design and applied cost.
Multiple scroll compressors used in parallel circuits can modulate the capacity following the load requirement by cycling compressors on and off.
For example, a scroll trio configuration in two parallel circuits with the capability of multiple start/stops of each compressor per hour allows precise water temperature control and offers flexibility to modulate chiller capacity to match the building load effectively.
Furthermore, this is an efficient way to modulate performance as losses associated with this operation are minimal relative to other technologies available.
Emerson Climate Technologies research shows that scroll technology can deliver high part-load efficiency compared to more conventional screw compressors.
On average, there is a 15 per cent increase in seasonal efficiency for common system designs.
Commercial systems equipped with hermetic scroll compressors need minimal maintenance and do not require regular oil analysis, bearing inspection and compressor service. They also offer a broad operating range enabling reliable system operation under the most demanding conditions, including low ambient heating.
Copeland scroll compressors have been leading the industry with a wide range for commercial systems up to 140kW cooling capacity in single compressor applications and up to 280/420kW cooling capacity in tandem/trio configuration in a single refrigerant circuit.
Emerson has extended its compressor range to 210kW cooling capacity in a single compressor application (equivalent to 60HP), enabling OEMs to design commercial scroll chillers up to 800-1000kW.
For more information, see www.emersonclimateasia.com