Ground Source Heat Pump is heating up in Down Under

Significance 

Although the Australian domestic electricity market has witnessed a marginal decrease in recent years, the commercial and residential sectors still account for 13% of the country’s total energy consumption. The decline can be attributed to many factors, including improved housing design, increasing use of energy-efficient appliances and consumer reaction to high electricity tariffs. This suggests that Australian residents support adopting more energy-efficient practices that could further reduce domestic energy needs.

Adopting ground source heat pumps (GSHPs) is a promising strategy for reducing energy consumption. By using the constancy of subterranean temperature, GSHPs can enhance the performance of heating and cooling devices. They are also environmentally friendly and require less energy to operate. In the last few years, the application of GSHPs for domestic cooling and heating has gradually grown, especially in Australia. GSHP systems can either be open- or closed-loop configurations. Regardless of the type, it is important to conduct a geological survey that includes assessing water quality and quantity before designing any GSHP.

Despite the operation and environmental benefits of GSHPs, there are still several barriers to their widespread adoption, especially in the residential sector. These factors include inadequate knowledge and risk assessment, drilling and pumping limitations, high piping and operation expenses as well as derating of the heat exchangers. Thus, it is imperative to consider all the features when assessing GSHPs for potential application in the residential sector. In particular, there is a growing need to compare the performance of GSHPs with other alternatives like air source heat pumps (ASHPs) to find the best and most sustainable approach for the residential sector considering all the factors. Nevertheless, there has been little attempt to compare GSHPs and ASHPs through actual measurement.

Herein, a team of researchers from The University of Western Australia: Ms. Tine Aprianti, Mr. Evan Tan, Ms. Chan Diu, Mr. Ben Sprivulis, Mr. Greg Ryan, Adj/Prof. Kandadai Srinivasan and led by Professor Hui Tong Chua assessed the efficacy and practical feasibility of implementing GSHP and ASHP with the aim for determining a better approach for domestic applications. Two nearly identical and adjacent houses in Perth, Western Australia, were used for the study. In one house was installed a GSHP in an open-loop configuration while the other one was installed a conventional ASHP. The comparison outcomes of the performance of the two systems were based on actual data collected for two years covering all the seasons. The work is currently published in the International Journal of Energy Research.

The research team showed that for both heating and cooling operations, the coefficient of performance (COP) of the GSHP system was higher than that of the ASHP system. The cooling/heating capacities and COP were independent of the ambient conditions in GSHP but dependent on the same ambient conditions in ASHP. For cooling, the average COP of the GSHP system was 3.1, while that of the ASHP system varied between 1.3 – 2.8, dependent on the outdoor temperatures. Similarly, for heating, the average COP of ASHP ranged between 1.9 to 2.9, while that of GSHP was 3.9, independent of outdoor temperatures. It was worth noting that when borewells are part of the dwelling, GSHPs result in direct energy and operation costs savings as well as a reduction in greenhouse gases emissions.

In summary, the new Australian study compared GSHP and ASHP systems installed on adjacent near-identical houses in terms of their economic and environmental impacts. Overall, the GSHP exhibited superior performance to the ASHP in both cooling and heating. The GSHP was up to 100% and 60% more efficient than ASHP when used for cooling and heating, respectively. In a statement to Advances in Engineering, Professor Hui Tong Chua, corresponding author suggested that open-loop GSHPs show great potential for applications in the residential sector.

Ground Source Heat Pump is heating up in Down Under - Advances in Engineering
A two-year study shows that the Coefficient of Performance (COP) of a Ground Source Heat Pump (GSHP) can be up to 100% higher than an Air Source Heat Pump (ASHP) in cooling mode and up to 60% in heating mode.

About the author

Professor Dr Hui Tong Chua is the Head of Department of Chemical Engineering at The University of Western Australia. His research interest covers Heat and Mass Transfer, Thermodynamics, Process Engineering and Waste Heat Utilisation. Six of his international peer reviewed journal articles are among the top 1% percentile in the field of Engineering in terms of citation.

He is focussing on the applications of ground source heat pumps and Olympic sized geothermal swimming pools.  He is also a Non-Executive Director of Good Water Energy Ltd., which is focussing on baseload green electricity, hydrogen and ammonia productions.

Reference

Aprianti, T., Tan, E., Diu, C., Sprivulis, B., Ryan, G., Srinivasan, K., & Chua, H. (2021). Performance Comparison of Ground Source Heat Pump (GSHP) against Air Source Heat Pump (ASHP) for Domestic Applications: A case study in Perth, AustraliaInternational Journal of Energy Research, 4(2), 55-63.

Go To International Journal of Energy Research

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