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2014 August No.176
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SPECIAL FEATURE: Creating COMFORTABLE Living. Advanced refrige ration technology keeps buildings comfortable. A device known as a centrifugal chiller takes air-conditioning performance to new heights.




As TOKYO SKYTREE TOWN® in Tokyo and ABENO HARUKAS in Osaka reach far into the sky, they stand as modern symbols of Japan, representing too, an apex in cooling technology.
In both landmark locations, MHI's centrifugal chillers are at work. These highly advanced devices generate efficient thermal energy needed to air condition the building complexes, creating dependable, consistent comfort for the large number of visitors and workers every day. Let's see how MHI's technology helps afford a comfortable living environment in facilities like these and other large enclosed structures such as airports, museums, factories and more.

Comfortable living for a large commerce and tourism hub. District cooling and heating system

At around four times the area of the Tokyo Dome, the TOKYO SKYTREE® buildings and campus have mammoth cooling and heating requirements best met with an efficient district cooling and heating system. MHI's centrifugal chillers are at the core of this comprehensive system.

Helping achieve the highest level of energy savings and smallest carbon footprint in Japan

From early in its development, TOKYO SKYTREE TOWN® has remained committed to realizing signicant energy savings and to protecting the environment. By adopting the ecient district cooling and heating system that included MHI's centrifugal chiller, this thermal source concentration method (Note) recorded the highest energy eciency in Japan. Compared with conventional systems in which heat is supplied individually by each building, this method also can reduce 50 percent of the carbon footprint. On the strength of its 60 percent domestic share and successful global track record in centrifugal chiller performance, MHI's technology was specied as the system's primary heat source component and is a key contributor to a comfortable environment for about 110,000 people enjoying recreational activities and shopping at TOKYO SKYTREE TOWN® every day and evening.

(Note) A method to manage the heat source of multiple buildings such as the district cooling and heating system.

Chilled water for the cooling process is delivered through an approximately 3000 meters long district service pipeline.
Photo: District service pipeline
Photo: Centrifugal chiller (main plant)

Centrifugal chiller
(main plant)

The capacity of this device is equivalent to approximately 1,350 residential use air conditioners. Making chilled water in large quantities during the night when electricity usage and costs are less than during peak day hours, the system effectively contributes to energy savings.

Photo: TOKYO SKYTREE TOWN® and its vicinity

TOKYO SKYTREE TOWN® and its vicinity, whose total area is about 182,000 square meters. Numerous offices and shopping centers are located in this complex where the demand for cooling exists, no matter the season.

Photo: TOKYO SKYTREE Station

The concourse for TOKYO SKYTREE's nearest train station is cooled by chilled water produced by the centrifugal chiller.

Photo: TOKYO Solamachi

TOKYO Solamachi
With more than 300 stores, variable speed drive centrifugal chillers efficiently adapt to variations in air-conditioning demand, assuring consistent comfort.

Photo: Solamachi Shotengai Shopping District

Solamachi Shotengai Shopping District
Tourists and locals gather in stores and coffee shops along the 120 meters long corridor. The system supports long hours of air-conditioning demand.


31-story building with offices and commercial facilities. Chilled water for cooling each room is delivered from underground.

Keeping it cool in skyscrapers. Elevating the science of air conditioning

ABENO HARUKAS, the tallest building in Japan, is an urban gathering place for many as they navigate its numerous department stores, offices, hotels, and its adjacent transportation terminal. MHI's centrifugal chiller helps create cooling comfort for busy people up and down the 300 meters tall structure.

Less power is needed to convey chilled water to high places with MHI's original advanced technology.

Air-conditioning demand at ABENO HARUKAS occurs around the clock -- department stores and offices during the day, hotels and art museums during the night. MHI's centrifugal chiller is hard at work helping create a comfortable environment for people throughout this multistory building.
Although significant power is required to pump water to such a high elevation, the centrifugal chiller offers some special advantages that enable the task to be accomplished with surprising energy efficiency. By using brine (anti-freeze liquid), the centrifugal chiller can create very cold water. The lower the temperature of the water, the less water that is needed to achieve the desired cooling effect to air condition the building. That means less energy is needed. The variable speed drive centrifugal chiller also achieves a high COP (Note) by managing energy use when air-conditioning demand is low during spring or fall seasons and at certain times of the day. It is in this fashion MHI's technology contributes to comfortable conditions even in the tallest of buildings.

(Note) The figure indicates the cooling capacity for 1 kilowatt of consumed electricity. For instance, 6 COP can generate six times the amount of heat for one unit of consumed electricity.

Photo: Central monitoring room

Central monitoring room
Here, delivery of chilled water to each floor is controlled 24/7. When weather or a major event such as a sale at a department store may affect the demand for air conditioning, the control system automatically adjusts for changes.

Chilled water made 26 meter underground conducts thermal exchange at the relay point. It is delivered about 270 meter above the ground.

Air conditioning the upper floors of Japan's tallest building requires a highly efficient device to generate chilled water cold enough to compensate for its loss of thermal energy during its upward journey. MHI's centrifugal chiller, a proven performer at many such installations, is up to the task.

Photo: Hotel

Where cooling demand exists even overnight, guests enjoy constant comfort in rooms and facilities dependably supplied with air-conditioned air.

Photo: Cafe space (office area)

Cafe space (office area)
Business meetings and conversations are conducted in comfortable, refreshing environments.

Photo: Lobby

The system supports the ever-changing air-conditioning needs here and for all of the building's facilities.

Photo: Centrifugal chillers

Centrifugal chillers
Machine room located on the 5th floor underground. This is the core of the heat source generation that delivers chilled water to upper floors. To optimize the 24/7 operation, the variable speed drive centrifugal chillers and the brine centrifugal chiller are controlled in the central monitoring room to meet refrigerating capacity requirements.

Photo: Variable speed drive centrifugal chiller

Variable speed drive centrifugal chiller
The system intuitively manages production of chilled water not only during the hot summer season but also when air-conditioning requirements are lower, resulting in substantial energy savings in the operation of the entire building.

Demand for the centrifugal chiller grows worldwide

New and diverse applications for the centrifugal chiller here and overseas find it integrated with other high-efficiency products that together achieve greater performance and energy savings.

Industries laud technology's stability and reliability Becoming global leaders

It is not only office buildings and commercial facilities where MHI's centrifugal chillers are operating. This revolutionary technology also can be found at facilities that encompass huge areas like airports and factories, as well as hospitals, where safe, controllable environments are crucial.
When accurate temperature control is essential, as in the manufacture and warehousing of food products, air conditioning must operate dependably, 24/7, to maintain freshness and quality. The centrifugal chiller meets that challenge as well as other applications whose large load requirements demand an efficient heat source system.
As installations of the proven centrifugal chiller expand across the globe, people are finding them to be highly efficient, large capacity and energy-saving solutions for environments where comfort is important.

Prime examples of MHI's centrifugal chiller applications both in Japan and overseas Photo: Narita International Airport Photo: MEGMILK SNOW BRAND Co., Ltd. Ebina Plant Photo: Hotel Nikko Alivila Photo: Singapore Marina Bay Area
Photo: Centrifugal chiller applications: Image of Minato Mirai 21 District

Advancing the future of human- and environmentally conscious living as a leading energy manufacturer

The MHI centrifugal chiller enjoys the number one share of its market in Japan. The chiller's potential to integrate with other devices or as part of a distributed power supply carries the promise of a much more efficient global utilization of energy.
MHI will continue on its path of developing products that anticipate the changing needs of the world market, just as it will continue to contribute to the world community and environment while fostering cooperation with other progressive enterprises.

Study Page

"thermal energy" for cooling

What is the centrifugal chiller? How does it generate thermal energy for cooling? Let's explore how the centrifugal chiller generates thermal energy using the nature of heat.

Centrifugal chiller

Figure: How chilled water is created

Principle based on the relationship between heat and pressure

When a gas is compressed, it becomes hot; when expanded, it becomes cold. The centrifugal chiller employs this principle.
For example, when you continue to press the button on a spray can, you'll feel the can becoming cold. This is because as the gas in the spray can is released, it lowers the pressure, allowing the gas inside to expand. The centrifugal chiller creates chilled water for air conditioning by cooling a refrigerant -- applying this relationship between pressure and heat.

Using the nature of heat

The centrifugal chiller creates a large quantity of chilled water for air conditioning by utilizing the nature of heat. It can create a large quantity of chilled water with very little electricity, its capacity sometimes reaching 100 to 5000 RT (Note1).
Chilled water is created in the evaporator. When the refrigerant (Note2) becomes gaseous in the evaporator, heat is removed from water returned from the building, making the chilled water cold. The chilled water is then delivered to the building. On the other hand, the centrifugal compressor compresses the gaseous refrigerant to make it a hot and high-pressure gas. The gaseous refrigerant is cooled with cooling water and becomes liquid. Its pressure is further lowered in the expansion valve and returned to the evaporator. Chilled water is efficiently created using this cycle of refrigerant changing states.

(Note1) Unit to indicate performance. One RT is equivalent to approximately one residential air conditioner.
(Note2) That which carries heat. MHI's centrifugal chiller uses an environmentally conscious HFC-134a (chlorofluorocarbon alternative) with a zero-ozone depletion potential.

Figure: To use energy efficiently

Combining a centrifugal chiller with another machine, you can create a more efficient system. For example, MHI has developed the Heat Source Control System, which optimally controls high performance, and the air-to-water heat pump module chiller "Voxcel." By combining these, power consumption can be reduced by about 65 percent compared to an absorption chiller (Note).
Moreover, when this system is combined with a gas engine equipped cogeneration system (CGS), the efficiency of the CGS can be further improved, since chilled water is made with the centrifugal chiller in the summer and hot water is created with waste heat from the gas engine in the winter. Energy is fully used without waste for much higher efficiency of the operation.

(Note) A chiller (or a machine) that burns gas to make chilled water using a chemical reaction.

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