Results in from major refrigeration and air-conditioning bench tests

by Sophie Berrill
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A significant portion of the electricity grid is consumed by refrigeration and air-conditioning (RAC) systems worldwide.

Combined, this industry is the largest user of synthetic greenhouse gases and ozone depleting substances in Australia, according to the Department of Climate Change, Energy, the Environment and Water (DCCEEW).

In 2022, the DCCEEW engaged independent testing facilities, including the CSIRO and SuperCool Asia, to bench test a selection of RAC equipment against common preventable faults to capture any impact on overall system performance and energy consumption. The goal was to determine the benefits of regular equipment maintenance.

The DCCEEW has published its findings across multiple reports. Overall, they clearly demonstrate that preventative maintenance minimises technology failure, reduces refrigerant leaks and increases the energy efficiency of properly installed equipment.

The tests

SuperCool tested a refrigeration display cabinet and a remote walk-in cool room. A number of common faults were investigated, including condenser and evaporator blockages, over and undercharged system, and air and refrigerant contaminations. 

Meanwhile, CSIRO tested the cooling capacity, heating capacity, electrical power consumption and operating efficiency of a 7kW reverse cycle, non-ducted variable speed split system air conditioner, and a 16kW reverse cycle fixed speed package air conditioner. Simulated faults were applied to the units to see the effects of common preventable faults on air conditioner capacity and power consumption.

Key findings

Refrigeration 

  • For walk-in cool rooms, the impact of refrigerant contamination reduced system performance the most. This was followed by the condenser and evaporator blockages, increasing energy consumption by around 69 percent, 16.6 percent, and 12.5 percent respectively. 
  • The tests on refrigerated display cabinets revealed the impact of 40 percent condenser blockage had the greatest negative effect on system performance, where the energy consumption increased by 15.7 percent more than that of the reference run.
  • Simple maintenance works such as cleaning the coil routinely can significantly contribute to reducing the system load and its energy consumption.

Air-conditioning

  • Minor improvements in system efficiency can be attained by ensuring airflow paths are free. 
  • Substantial improvements can be attained by ensuring the refrigerant charge is correct and the system has been purged of non-condensables such as nitrogen or air.

The full results, including reports undertaken independently by Cresstec, can be found on the DCCEEW website.

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