Cover Feature
DEEP DIVE An innovative cooling system has allowed young and old to appreciate a piece of Australian naval history, and serves as a fitting tribute to a woman who believed in learning through experience. Louise Belfield reports. Sitting proudly in the water and moored alongside the Australian National Maritime Museum (ANMM) in Sydney’s Darling Harbour is a relic of the American‑Soviet Cold War of 1947–1991 – Australia’s HMAS Onslow submarine.
The existing ventilation system, comprising an axial fan, delivered unfiltered and unconditioned air through the air intake shaft within the conning tower into the cabins and was totally unsatisfactory. Tours had to be cancelled.
Decommissioned in 1999, this sleek, black, “silent patroller of the deep” clocked up more than 358,000 nautical miles in service before being donated to the ANMM.
“We have a number of volunteers and visitors doing regular tours of the sub, but with limited airflow and high temperatures, we had to stop that,” White says. “We looked at modifying the sub at one point by piping chilled water to it, but that wasn’t going to be viable. It was going to be far more cost‑effective to install a DX system.”
The sub is now an exciting and informative experience for young and old alike as they explore the cramped conditions and imagine what life was like for the sailors whose lives were in constant danger.
The challenge, however, was getting a system to fit into the tight space and meet the capacity requirements at the same time.
According to one ex-Navy officer, it wasn’t just the threat of enemy vessels that weighed heavily – the air quality was also “disgusting”, and the crew would go well over 12 hours a day without fresh air. Sadly, conditions inside the submarine as a modern tourist attraction have also been far from ideal.
UNSAFE TEMPERATURES Summer temperatures regularly topped 25°C, and the submarine cabins were 4–5°C higher. Conditions simply became uncomfortable and unsafe for visitors, volunteers and staff, says ANMM building services manager Craig White. Unsurprising really, with a black solid metal hull and deck and very little space inside. 20
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in. His late wife Samim had been an early childhood development expert with double master’s degrees in this field, before she succumbed to motor neurone disease (MND) in November 2019 [see breakout]. She always said that “children learn through experience”. So, to ensure that children could have that experience, and as a tribute to his late wife, Nathwani offered to design and, with the help of his family, cover the costs of the installation of an air conditioning system to ensure year-round access.
TIME FOR A SEA CHANGE
“Because of the very limited space and having to also maintain the historical aspects of the sub, we couldn’t just hang a modern aircon unit on the wall,” White says.
Aware that no ordinary system would do the job, Nathwani turned to the team at Aerotherm, who had successfully installed an unusual system he designed at a Sydney University laboratory called the Indoor Environment Quality (IEQ) laboratory.
“Another challenge was getting a fan coil unit to fit into the conning tower [the periscope housing]. Where you would normally put a fan coil system in the ceiling space of a building, the available entry space through an access hatch into the conning tower was only 450w x 600h.”
“But that lab is not quite as cramped as the sub,” Nathwani says. “I asked if we could convert the lab idea into an aircon system for a submarine and how big a unit we could fit in. That took some working out because there was a size constraint. It clearly needed to be custom made.
On learning that the tours of the submarine were being cancelled during hot days, including during summer school holidays, Ashakali (Ashak) Nathwani AM, researcher and senior lecturer in HVAC at the University of Sydney stepped
“The final design involved provision of a custom-built split air conditioning system with the air handling unit located in the snorkel mast, replacing the fresh air fan, and the condensing unit located in the chamber below the main cabins.
April–May 2022
