Page 17 - Climate Control News Aug-Sep 2020

Chiller Feature
HVAC gets a green makeover
POWERING UP ENERGY SAVINGS
Almost a quarter of all electricity generated in Australia is used to power HVACR systems, and around 80 per cent of this electricity is generated using fossil fuels.
Through its energy use, HVACR contributes significantly to the country’s emissions. HVAC systems use 65 per cent of a building’s energy use with 25-35 per cent consumed by chillers producing chilled water for air conditioning. As a result, chillers are a critically important part of any energy efficiency strategy.
According to the Department of Environment Fact Sheet, poor maintenance can increase chiller power consumption by as much as 20 per cent.
“They are ideal for space cooling and process cooling in commercial, residential, and industri- al applications as they are dependable, cost-ef- fective, and are available in water-cooled or air- cooled types ranging in size from 20 to 60 nominal tonnes each.
“Also, they are compact in format, energy-effi- cient, and flexible in function and can be con- nected to 12 units in parallel to increase the overall cooling capacity of the chiller systems.”
The most significant advantage of modular chillers is 'modularity' – which means when cooling requirements are low, operators can shut down any unit and switch to any number of units when the need is high. This also means re- duced downtime.
“ONE OF THE BIGGEST TRENDS TAKING PLACE IN THE MARKET TODAY IS THE GROWTH OF MODULAR CHILLERS, ESPECIALLY IN THE ASIA PACIFIC.” – REPORTS AND DATA RESEARCH REPORT.”
“In the HVAC industry, the demand for modu- lar chillers has gained momentum as it is lighter, more efficient, and lowers the required volume of refrigerant compared to other heat exchangers,” the Reports and Data research report said.
“Modular chillers are widely used for efficient heat transfer between the refrigerant and air in AC systems and heat pumps. Besides, modular chillers are used in residential and commercial refrigeration applications, due to compact de- sign, lightweight, and lower hold-up volume.”
HVAC IS AN outdated business that has changed very little over the last 50 years, ac- cording to Jack Alvarenga, research scientist at the Wyss Institute.
He said the global demand for cooling con- tinues to rise, which is why it is time to ad- dress the environmental impact of cooling via new technology.
Alvarenga is working with a team at Harvard University’s Wyss lab on an innovative solution. The vast majority of today's air conditioners still use mechanical vapour compression, which has not changed much since the 1920s,
despite mounting environmental concerns.
It is a system that uses potent refrigerants
and requires a lot of energy.
Indirect evaporative cooling (IEC) cools via
the evaporation of water but IEC systems con- tain a heat exchange unit that isolates the evaporating water from the air removing heat without adding humidity.
The good news is that IEC systems require very little energy to run but they are difficult to manufacture due to the complexity of the heat exchange unit, which makes them expensive and their performance difficult to optimise.
The technology being trialled at Wyss is called cold-SNAP (Superhydrophobic Nano- Architectured Process), which uses up to 75 per cent less energy than mechanical vapour compression air conditioners, and relies on wa- ter rather than refrigerants.
The cold-SNAP system achieves its high per- formance thanks to the integration of old and new: ceramic, one of the earliest, cheapest, and most widely available building materials; and a
novel surface coating developed recently in the lab of Wyss Core Faculty member Joanna Ai- zenberg, Ph.D. The coating's nanoscale rough- ness makes it super water-repellent and, when applied to a slab of highly water-absorbent ce- ramic, the result is a very efficient heating ex- change unit that can effectively isolate evapo- rating water from cooled air. Because ceramic is very malleable, an entire heating exchange unit can be produced via the extrusion or 3D printing of a single piece, and its shape can be adjusted to maximise the surface area availa- ble for heat transfer and evaporation.
‘IT’S TIME TO ADDRESS THE ENVIRONMENTAL IMPACT OF AIR CONDITIONING.’
– JACK ALVARENGA, SCIENTIST.
The hydrophobic coating is then selectively applied to the components that will manage the flow of dry air, coupled to a water pump, fan, and controls.
Preliminary studies have indicated that the cold-SNAP system can be up to four times more efficient than conventional air condition- ers as measured by the Coefficient of Perfor- mance (COP).
The team is currently exploring different manufacturing techniques through a pilot study to see how the system performs in real- world hot and humid conditions.
Air Conditioning today relies on a lot of energy and potent refrigerants.
CLIMATE CONTROL NEWS AUGUST-SEPTEMBER 2020
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