Many millions of visi­tors come to Macao not only for the many historic build­ings dating back to the Portuguese colo­nial period. More than 30 casinos also make the city in the Pearl River delta a popular desti­na­tion. So that the guests are not only well enter­tained but also feel thor­oughly comfort­able, the oper­ator of the casino contracted the company Saiver to plan the air-condi­tioning system of the complex, which is open for busi­ness around the clock. The heart of the complex is a half-scale replica of the Eiffel Tower complete with three visitor plat­forms.

Saiver’s AHUs are completely preassem­bled for plug & play instal­la­tion on-site, which saves time and money. (Photo | ebm-papst)

Saiver is a glob­ally oper­ating manu­fac­turer of air handling units (AHUs). The company has entered a joint venture for the Asian market with Welcome Air Tech Ltd., a HVAC equip­ment supplier based in Hong Kong. Together they designed and built a total of 350 AHUs for the large-scale project in Macao, which not only ensure the supply of fresh air to the building but also regu­late the temper­a­ture and humidity inside. For the air condi­tioning, 1,100 RadiPac EC fans from ebm-papst were installed; they circu­late more than 12,000,000 cubic meters of air per hour. ebm-papst specially designed the centrifugal fans of the RadiPac series for use in air condi­tioners and venti­lation units.

Custom-made solu­tions

The require­ments for air condi­tioning in this project are complex. From the hotel rooms and stores to the giant recep­tion hall and the theater, the require­ments for air condi­tioning vary from place to place. Tailor-made solu­tions were devel­oped and the units were adjusted to the specific condi­tions.

From the hotel rooms and stores to the giant recep­tion hall and the theater, the require­ments for air condi­tioning vary from place to place.

Three different RadiPac models are used for the venti­lation units: size 310 with an air flow rate of 5,000 m³/h, size 450 with an air flow rate of 10,000 m³/h and lastly size 630 with an air flow rate of 20,000 m³/h. The AHUs were completely prefab­ri­cated in China and there­fore easy to install on site. This saved time at the construc­tion site and meant lower costs for the builder. The RadiPac EC fans permitted lean produc­tion at the customer’s end; they are designed for plug & play instal­la­tion.

Compact design

It was impor­tant to the casino oper­ator to maxi­mize the usable space in the building, so space-consuming equip­ment rooms had to be avoided wher­ever possible. Thus, a lot of perfor­mance had to be accom­mo­dated on little space. The engi­neers designed the AHUs so that they can be mounted on plat­forms in the ceiling and docked directly onto air distri­b­u­tion ducts. For this type of appli­ca­tion, the other­wise commonly used belt-driven fans were unsuit­able, primarily because the design prin­ciple of this drive form requires a rela­tively large amount of space: vari­able frequency drive, motor, belt drive and fan are each installed indi­vid­u­ally and sepa­rately.

It was impor­tant to the casino oper­ator to maxi­mize the usable space in the building.

This is different with the RadiPac: elec­tronics and motor form one unit, which saves space and also enables easy instal­la­tion. An inte­grated control elec­tronics system replaces the external vari­able frequency drive and, as the elec­tronics and the motor are ideally matched to each other, addi­tional elec­tronic filters and shielded cables become super­fluous. This way, the length of the venti­lation units could be reduced.

The AHUs can be dimen­sioned smaller with the RadiPac EC fans. (Photo | ebm-papst)

Powerful, reli­able and effi­cient

In spite of their more compact design, the AHUs had to be powerful enough to move the air under suffi­ciently high pres­sure through the air-condi­tioning ducts, some of which extend over three stories. Depending on where the fans are used, air flows of up to 80,000 m³/h are required. Saiver there­fore relied on FanGrids with up to six RadiPac EC fans arranged in parallel.

Air flow through a heat exchanger with a FanGrid solu­tion and ...

an indi­vidual fan solu­tion. The latter exhibits non-uniform flow through the heat exchanger and thus poorer heat transfer values. (Photo | ebm-papst)

The parallel oper­a­tion of multiple small fans has huge advan­tages over large indi­vidual fans in venti­lation tech­nology. The even flow through the heat exchangers or filters leads to better heat transfer perfor­mance and more effi­cient filtering of the air [Figure 4]. In addi­tion, several small fans require much less space, which reduces the costs of the system.

Redun­dancy for more reli­able oper­a­tion

The fans use EC motors with an external rotor design, i.e. grid-fed, perma­nently ener­gized, synchro­nous motors with elec­tronic commu­ta­tion, also called BLDC (brush­less DC) motors, which boast effi­cien­cies that are far above effi­ciency class IE 4. They work much more effi­ciently than a fan driven by an asyn­chro­nous motor via belt.

Effi­ciency of a belt-driven fan compared to a RadiPac EC fan. (Photo | ebm-papst)

Belt-driven fans also have the draw­back that they are rela­tively high-main­te­nance and break down as soon as just one compo­nent fails. If the only fan breaks down, this in turn means a complete failure of the venti­lation system.

The fans use EC motors which work much more effi­ciently.

Not only can this be unpleasant for guests because of the rising temper­a­tures, it can also become dangerous quickly if the CO2 concen­tra­tion in the air increases in conse­quence. So that the required air volume is provided in the building at all times, the FanGrid was laid out redun­dantly. This para­meter spec­i­fies how many fans can be switched off without drop­ping below the required air flow. The most powerful unit manages to move 80,000 m³/h against 1,500 Pa – with great energy effi­ciency thanks to EC tech­nology.

Quiet and smart

Hotel guests as well as visi­tors to the theater and casino not only appre­ciate the good air quality, they also gladly do without the disturbing noises. The RadiPac EC fans score over the belt-driven fans in this aspect as well. They are much quieter, espe­cially at low speeds. This is due to the commu­ta­tion and the stator design in the EC motors, which ensure low-noise magne­ti­za­tion of the main field. Thanks to the MODBUS inter­face in the EC motors, they are ideal for inte­gra­tion in Building Manage­ment Systems (BMS). The oper­ator can also monitor the energy consump­tion and speed of the fans remotely.