A considerable portion of the electricity grid is consumed by refrigeration and air-conditioning (RAC) systems worldwide. In 2016, around 23.6% of the electricity production in Australia was used by RAC equipment 1.
Electricity use related to greenhouse gas emissions and direct emissions from RAC equipment produced around 61.3 Mt carbon dioxide equivalent (CO2e) of greenhouse gases or approximately 12% of Australian national greenhouse gas emissions in 2020 2.
This substantial emissions data presents an opportunity to take a closer look at how equipment manufacturers and owners can ensure their RAC equipment is running as efficiently as possible. Not only does this lower emissions, but it also reduces the running cost of refrigeration and air-conditioning systems and prolongs its lifespan.
As with any equipment, faults can cause the system to operate inefficiently or malfunction, which can lead to increased energy consumption. Typical RAC faults include:
heat exchanger blockages
refrigerant under/overcharge, and
refrigerant contamination
It is these faults that were the focus of our bench testing project for the Department of Climate Change, Energy, the Environment and Water.
SuperTest and the CSIRO worked with the Department of Climate Change, Energy, the Environment and Water (DCCEEW) to scientifically prove that HVAC&R system maintenance has a positive impact on energy use.
The test investigated the efficiency of a healthy and well-performing refrigeration system – the reference unit – and compared the effect of faults on the overall system and its energy consumption.
For this project, we performed NATA-accredited testing in accordance with ISO 23953-2 for integrated refrigerator display cabinets (specifically to provide determination aligning to the Greenhouse and energy minimum standards (GEMS) 2020).
SuperTest provided the facility, approved protocols, rigorous testing, and detailed reporting required to ensure integral refrigerated display cabinets used in the sale and display of food and beverages operate efficiently.
The first test used a typical 2 door vertical refrigerated display cabinet set up in a controlled environment, without a heat load.
A reference test was run, and results were recorded before running a selection of performance tests, with faults introduced and their results recorded.
A typical walk-in cool room was also set up under controlled conditions, with similar fault tests run in comparison to a reference test.
The faults introduced were a blocked condenser, blocked evaporator, refrigerant under and overcharge, and refrigerant contamination.
The tests and subsequent reports aimed to capture insights into the increases in energy consumption when single (and multiple) faults are simulated in equipment under a controlled environment.
SuperTest found that blocked filters, contaminated refrigerant and other common, preventable issues led to an increase in energy consumption.
The impact of contaminated refrigerant in the walk-in cool room setup had the greatest negative impact on system performance, with the energy consumption increasing by 70% more than that of the reference run.
The chart on the right shows the system’s energy consumption for each introduced fault in comparison to the refrigeration cabinet reference test. Numerous faults had substantial impacts on energy use, with the impact of 40% condenser blockage having the greatest negative impact on system performance, where the energy consumption increased by 15.7% more than that of the reference run.
Likewise, this chart reveals the changes in walk-in cold room energy consumption when common faults are introduced.
It’s clear that refrigerant contamination has a sizable effect on efficiency.
The below chart shows a comparative analysis of different test outcomes for the refrigerated cabinet test. The green bar represents average power consumption, while the yellow bar, the energy consumed. The red and black dotted lines represent the reference run for power and energy consumption, respectively.
As evidenced, condenser blockage (40%), refrigerant and air contamination had the greatest impacts, consuming the largest increase in power and reduction in performance efficiency.
The results differed for the walk-in cool room, with contaminated refrigerant having the biggest impact on energy consumption.
Both reports (available in full on the DCCEEW website) provided insights into the amount of energy consumed for individual faults – and a summary of how much worse it can get if multiple faults coincide.
When several faults or maintenance issues co-exist in a system, it is likely that energy use would increase substantially (approx. 36% in the cabinet test undertaken).
Based on the results, it was concluded that regularly scheduled system maintenance could significantly increase efficiency and reduce energy use.
Well-maintained and efficiently running equipment results in a reduced carbon footprint, lowering excess demand on the power grid and reducing the impact on the environment.
By staying on top of maintenance, it is possible to:
In many cases maintenance procedures are very simple, such as coil cleaning – however the financial outcome and environmental benefits are significant.
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14 Motorway Circuit
Ormeau QLD 4208
Australia
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