“Making a Comfortable andBetter Way of Life”-From Residential Air Conditioners toDistrict Heating and Cooling SystemsHIROOKI SHIBANAI
GENJIRO KIMURAHISASHI HATTORITAKASHI KAWAKAMI

implement sophisticated marketing strategies, improvesales efficiency, and establish superlative, high-quality
production bases.

1.Introduction
Air conditioning has become essential to create comfortable spaces in residences and offices for human living,while refrigeration has become indispensable to frozen
food and cold storages for keeping food fresh. In order
to meet various customer needs, MHI produces an extensive range of products as an all-round manufacturerof air-conditioning and refrigeration equipment. These
products include such items as air-conditioners for residences, air-conditioners for offices and stores, automobile
air-conditioners, centrifugal chillers and absorption chillers for large scale buildings and district heating andcooling plants in the air-conditioning field, refrigeratorsfor cold storage, and truck and marine refrigeration units
in the freezing and cold storage field, amongst others.
MHI’s refrigerating equipment business has its origin
in the production of refrigerated cargo carriers and icemaking machines for ships before World War II. After
the War, MHI has developed and produced many products ever since it first made electric refrigerators andice cream freezers for the Occupation Forces, playing aleading role and advancing with the progress of the refrigeration and air-conditioning industry in Japan.
The Air-Conditioning & Refrigeration System Headquarters of MHI is continually striving to develop many
products that are high in efficiency, low in noise, andfriendly to the environment. The aim is to create ahealthy and comfortable living space for people while
protecting the global environment under the motto “Takepride in letting people around the world feel comfortable and rich through our air-conditioning andrefrigeration products.” Moreover, MHI is intent on fulfilling recently expanding customer needs concerning
reliability and service. In order to cope with rapidchanges in the business environment, such as the emergence of China and Korea, MHI is emphasizing its effort
to strengthen the business fundamentals that will enable the company to compete successfully in an
increasingly severe and competitive environment, by enhancing its ability to develop new products, prepare and2. PastThe past of the air-conditioning and refrigeration business of MHI can generally be said to reflect a history of
successful expansion of market, and the overcoming ofdifficulties such as oil shocks and cool summers throughthe development of new products, all the while matching or contributing to the pace of Japanese industrial
progress since the end of the War. The following is a
description of the major products developed by MHI, fromthe beginning of 1960s to the present, during which time
remarkable growth has been achieved in the air-conditioning and refrigeration business which started fromthe application of refrigeration and cold storage.
The authors will be most grateful if this article in somesmall way helps contribute to a better understanding of
the cooling and heating equipment business of MHI
through a review of the past and look at the future of
the business.
2.1 Room air-conditioners
During the ten-year period from 1955, air-conditioners were called coolers and used exclusively to cool rooms.
At that time, in advance of others, MHI advocated thatthe use of a heat pump would make air-conditioning more
comfortable and efficient, and as a result promoted the
spread of heat pump systems throughout the Japanese
domestic market. Heat pumps had been defined as lacking in any warming feeling because of its low air outlet
temperatures. However, the Warp 60 put on the market
by MHI in 1987 demonstrated that a warming feeling
could also be attained by heat pump systems if they produce a breeze with an outlet temperature as high as 60oC.
As heat pump systems became leading products in the
air-conditioner market and the number of hours that they
were used increased each year, the major concern of users shifted to realizing ever-better energy-savings in
air-conditioners. Accordingly, MHI developed a DD scroll
compressor that was characterized by high efficiency and
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1960

1970

1980

1990

2000

Era of air-conditioners used exclusively for cooling

Era of air-conditioners used for both heating and cooling

CoolerHeat pump inverter type air- conditioner(high efficiency air- conditioner)

Silent operation, low vibration, clean outlet air, bacteria resistance, deodorization, power-saving, use of new refrigerants
Window type room coolers

Split type air conditioners

Window type heatpump air-conditioners

Compact typeair-conditioners

Ventilation type
Fuzzy control
Inverter typeair-conditioners
air-conditioners
Internet-based"Warp 60," high in
air-conditioners
PMV control
blowout air temp.
DD scroll energy-saving
type air-conditioners

Wall type heat pump
air-conditioners
More than 70% ofhouseholds in Japan had
room air-conditioners

Hottest summer in 40 years
Intensely hot summer(million sets)
Overall8
demand of room
air-conditioners
in Japan
6
Very hot summer
4

Intensely hot summer

Coolestsummer in
40 years

Generation of El Nino

Cool summer

20Fig. 1 Progressive history of room air-conditioners

low noise in order to realize the compatibility of comfort
and low energy consumption. As a result, the excellent
energy-saving capabilities of the unit were highly regarded and recognized in the awarding to MHI of prizes
by the Director of the Agency of Natural Resources andEnergy at the Energy Conservation Center Japan in both1996 and 1997. Fig. 1 shows an overview of the progressof development of air-conditioners at MHI.
2.2 Packaged air-conditioners
Packaged air-conditioners began to spread into restaurants and department stores in the ten years from1955. Demand for the units soon also expanded to offices and stores, as coolers became indispensable in thesummer. In order to reduce the space occupied by a packaged air-conditioning unit, MHI developed newspace-saving types of units, such as ceiling pendant andceiling recessed types of units. This resulted in the affixing of the nickname “MHI of ceiling types” to thesetypes of units that have become the main stream inpresent-day packaged air-conditioners.
Because the spread of air-conditioners raised the peaklevels of electric power demand in the summer, MHI undertook research into ice thermal storage typeair-conditioner that utilized electric power at night during off-peak time periods in an attempt to level off electric
power loads throughout the day. MHI successfully commercialized packaged air-conditioners that were
equipped with an ice thermal storage for peak cut andpeak shift based on the results of joint research by

Tohoku Electric Power Co., Inc., Tokyo Electric Power
Co., Chubu Electric Power Co., Inc., The Kansai ElectricPower Co., Inc., Chugoku Electric Power Co., Inc., andKyushu Electric Power Co. This new type of unit madeit possible to realize large reductions in peak electric
power consumption. Owing to this development, MHI
received a prize from the President of the Japan Machinery Federation in the 1996.
2.3 Large sized refrigerating machine
Large sized refrigerating machines equipped with centrifugal chillers have been successively delivered by MHI
not only for high rise buildings but also industrial plants
since the beginning half of 1960s. In fact, MHI came to be
the dominant player in the field of large sized refrigerating machines in Japan. In particular, MHI has beendeveloping large capacity chillers ever since the company
delivered chillers for the first district heating and coolingsystems for the first time ever in Japan at the site of theworld exposition fair in 1970 and at Senri New Town. As aresult, MHI delivered the world’s largest capacity steam
turbine driven centrifugal chiller with a capacity of 10 000
tons of refrigeration (RT) to the Makuhari Shintoshin District Heating and Cooling Plant of the Tokyo Gas Co., Ltd.
in 1990. This was followed by delivery of the world’s largest absorption chiller with a capacity of 5000 RT to the
Minato Mirai 21 District Heating and Cooling Service Co.,
Ltd. in 1999. The latter was highly evaluated and recognized for its highly efficient performance, resulting in MHI
being awarded the prize of the Director of Agency of NaMitsubishi Heavy Industries, Ltd.
Technical Review Vol.40 No.1 (Feb. 2003)2

tional Resources & Energy at the Japan Machinery Federation in the 2000 and the technology prize of Japan
Society of Refrigerating and Air Conditioning (JSRAE).
2.4 Automobile air-conditioners
The development of air-conditioners for use in cars andsimilar motor vehicles began in nearly 1957. However,
MHI’s full-scale advance into this market started in 1968,
when MHI passenger cars took a considerably high shareof the market and taxi air-coolers began to spread. During
the last half of the 1970s, MHI developed automatic airconditioners for cars that could automatically control thetemperature in the passenger cabin, so that comfortableair-conditioning became enjoyable throughout the four seasons of the year. From the beginning of the 1980s, MHI
developed scroll compressors for car air-conditioners thatwere characterized by their high efficiency and low noiselevels. In 1990, MHI developed the first scroll compressor
in the world capable of preventing excess cooling using
capacity control. This scroll was awarded the technology
prize of JSRAE.
2.5 Low temperature physical distribution system
Since about 1963, low temperature physical distributing systems began to spread and facilities for freezing andcold storage for retaining the freshness of food began to beinstalled in food producing districts, transportation systems, and in food consuming districts. Semi-hermetic
refrigerators for freezing and cold storage as well as refrigerating units for prefabricated freezing and cold storage
have also been developed by MHI. At present, these facilities are major products of MHI’s low temperature business.
Since 1968, MHI developed truck refrigeration units andcompleted a series of such units of various sizes and applications ranging from use in compact cars through to large
sized vehicles. In 1979, MHI developed under-mount typeunits driven by diesel sub-engines for large sized vehicles.
The low fuel consumption and excellent car body stability
features of these units made them a hit product and helped
position MHI as the top manufacturer in this field.
MHI began to produce marine refrigeration units in
1956. After that, as containerization progressed, flushmount type refrigeration units were developed in 1971 andsuper-thin end wall type units developed in 1973. The latter satisfied user demand for storage capacity to be madeas large as possible within a limited container volume.
These units have come to be the present foundation of themarine refrigeration unit business of MHI.

Average COP for bothheating and coolingStandard COP specified by
Revised Rationalization in Energy Use Law
5.89

6
4.90
4

3.05

4.55

3.53

2
0

1992

1996

Year

1999

2002

Fig. 2 Trend in average COP of heating and cooling for
MHI air-conditioners (2.8 kW class)of 2010 in Japan for the complete abolition of HCFC refrigerants used in new products. Bearing in mind that the
improvement of efficiency is one of the most important
points of concern in preventing global warming, MHI has
already cleared the standard heating and cooling average
COP (Coefficient of Performance) of 4.90 specified to beachieved in the 2004 stipulated in the revised Energy-Saving Law. As can be seen in Fig
Fig.. 2 , present day airconditioners have reached a level of efficiency that is about
twice what it was about ten years ago.
The SE series of high quality units was developed tomeet the need for superior air-conditioning performance,
especially for realizing true comfort in terms of temperature, humidity and cleanliness of the conditioned air.
In terms of comfort and excellent performance, the position of these units in the top class of this industry has
been achieved by the adoption of a JET air current thatapplies jet engine technology as well as high accuracy temperature control.
JET & warp
An ideal wind path design can make a room comfortable within a very short period of time. This isbecause a large amount of cool or warm air can be
spread into all corners of the room efficiently withless power consumption. For instance, such an approach would make it possible to heat a room from
10oC to 20oC in only three minutes at an outside temperature of 2oC. In addition, the operating sound of
the indoor unit has been reduced to 19 dB in the silent mode of operation thanks to a special design thataims to achieve operation which is so silent that nosound is noticeable even at night. Fig
Fig.. 3 shows an.

3. Present
3.1 Room air-conditioners
In developing room air-conditioners, MHI has always
striven to reduce loads on the global environment, such as
global warming and depletion of the ozone layer. Since
1997, MHI began to exchange HCFC for HFC refrigerants
as part of measures to protect the ozone layer. The exchange is scheduled to be completed before the target dateFig. 3 External view of indoor unit of air-conditioner(2.8 kW class, high-end machine)

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As a result, the COP reaches 4.40 in a 2.5 HP unit,
which is the top level in the air-conditioner industry,
and attains an energy-saving rate in which annual
electric power consumption is reduced by 47% compared with that of conventional 5 HP MHI units.
Low noise
Noise levels during operation have been remarkably reduced by 6 dB in an outdoor unit and 4 dB in
an indoor unit, in comparison with the noise levels of
conventional units.
Adoption of powerful enzyme-based disinfecting filters
Filters impregnated with special enzymes havebeen adopted in room air-conditioners to remove moldand bacteria in order to realize clean air-conditioning. This is the first unit of its type in Japan.
Remote controller equipped with weekly timer function
MHI has developed a remote air-conditioner controller with functions that can be set one week inadvance that is the first of its kind in Japan.
The figure in the headline shows external views ofboth an indoor and outdoor unit equipped with the“hyper inverter”.
3.2.2 Air-conditioning systems for larger buildings
Recent buildings are often built as integral structures,in which offices and stores are combined. As a result,the air-conditioning system for such buildings is divided
into small cell units and each cell unit works differently
in terms of operation time, settings, and the like, so that
individually distributed air-conditioning is required. The
adoption of intelligent systems increases the amount of
OA equipment used, so that both cooling and heating
functions are often operated simultaneously in the samebuilding. MHI has completed the multi-KX2 series system to accommodate such diverse operational conditions
in air-conditioning. These systems have been adopted
not only in Japan but also overseas in Korea, China, andEurope, and have become one of the main products of
MHI. The major features of the system are briefly summarized below.
Plenty of variation in indoor units
A very wide variety of indoor units are available,
including ceiling recessed type, ceiling recessed compact type, and duct type units. Individual units withcapacities ranging from 0.8 through 10 HP can be combined.
Large capacity outdoor units
In addition to integral type units that range from
5 to 16 HP, large capacities from 18 through 40 HP
have been realized by the combination of 8 and 10 HP
units.
Simultaneous heating and cooling operation
Heating and cooling functions can also be freely
selected and operated simultaneously with a single
outdoor unit such as multi-KXR.

.
.
Fig. 4 Air flow of indoor unit.

external view of a 2.8 kW class high quality unit, while
Fig. 4 shows the flow of air with such a unit.
The various following means are adopted in orderto improve the cleanliness of the air.
Powerful disinfection by enzymes
MHI has developed the first air filter in the world
for use in an air-conditioner. It disinfects mold andbacteria by enzymes in order to always keep the insides of the units and room clean.
Cleanliness by ventilation
Based on experience gained over a five-year period
as a pioneer in ventilation type air-conditioners, MHI
has developed a new ventilation type air-conditioner
that keeps the indoor environment healthy throughthe use of a ventilation fan that discharges CO2, formaldehyde, and other chemical vapors that are
impossible to remove by a filter.
Negative ions
MHI has developed a system for supplying negative ions that are thought to be effective in mental
therapy.
In addition, MHI has developed an air-conditioner
provided with advanced “e-@ir” technology that makes
it possible to control air-conditioners via a remote controller using IT or a portable telephone.
3.2 Packaged type air-conditioners
MHI produces a wide range of packaged type air-conditioners. These include store air-conditioners, building
air-conditioning units, ice thermal storage units, and gas
heat pump (GHP) type air- conditioners. All these units
use the HFC 407C refrigerant, which does not deplete
the ozone layer, as one means of protecting the global
environment.
3.2.1 Air-conditioner for stores
MHI has developed “Hyper Inverters” for store airconditioners that have the features described below.
Highly efficient and energy-saving operation
Highly efficient and energy-saving operation has
become possible in all operational ranges, thanks tothe adoption of a hybrid type controller, in which thecontrol range of the inverter driving the compressor
is divided into both low speed and high speed ranges.

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Fig. 5 External view of inverter type multi-KX2 outdoor unit (32 to40 HP)

Electric power consumed by
non ice-thermal storage type
unit with the same HP

22

Electric power consumed
by the HiCoP Ice 90

16
18
Time
Fig. 6 Illustration of ice thermal storage system (HiCoP Ice 90)
operation pattern (for cooling)

.

8

35%

Peak shift operation

Peak cut operation

90%

Peak shift operation.

35%

Ice thermal
storage

Electric power consumed

Fig. 5 shows an external view of an outdoor unit ofmulti-KX2 for buildings.
3.2.3 Ice thermal storage systems
Ice thermal storage system utilizes ice or hot waterproduced by less expensive electric power during thenight for air-conditioning during the daytime. MHI offers both series of large capacity Multi-HiCoP Ice 60 and
HiCoP Ice 90 systems. The major features of these systems are briefly summarized below.
High efficiency
The icethermal storage systems developed by MHI
have achieved a daily COP 2.2 or more in total of electric power consumption for ice thermal storage during
the night, and that for cooling rooms using ice thermal storage during the daytime. This high efficiency,
the highest level in Japan, has been obtained by improving the performance of both the ice making heatexchanger and the outdoor unit.
Peak cut and peak shift method
In the HiCoP Ice 90 series, the compressor of each
outdoor unit is stopped during the time zone from 1
pm through 4 pm in the summer, when power consumption peaks, so that 90% of the power consumption
is cut. During other time zones, 35% of the power
consumption is shifted by subcooling the refrigerant.
These cuts in power consumption and use of lower
rates make it possible to realize substantial savingsin the amount paid for power. Fig. 6 shows an operating pattern for peak cut and peak shift. In addition
to the HiCoP Ice 90 series, the HiCoP Ice 60 series
has also been commercialized. This series achieves
reductions in power consumption of as much as 60%
and 40% by peak cutting and peak shifting, respectively.
Heating by use of heat accumulator
Strong market needs have led to the addition of a
hot water type heat accumulating mode to the ice thermal storage system. Heat is accumulated by holding
hot water at about 35 oC in a heat accumulating tankusing less expensive electric power during the night.
The heat accumulated is then used for heating during the daytime. A “heating capability- raising mode”
has become applicable to increase the heating capability of the heat accumulator.

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3.2.4 Gas heat pump (GHP) type air-conditioners
The GHP type air-conditioner series ECO-5 using a
new refrigerant has been developed to satisfy the following customer needs.
Energy-savings
Efficiency has been increased by about 20% compared with conventional units by the improvement of
the efficiency of the engine, the application of electronic control, and the adoption of low-pressure loss
refrigerant circuitry originated by MHI. As a result,
the COP value for these units reaches 1.31 on average for cooling and heating, which places them in the
top class in Japan.
Reduction of environmental load
The emission concentration of NOx (nitrogen oxides) has been reduced by 40% through the applicationof electronic control and improvements to the EGR(Exhaust Gas Recirculation) system, in which a portion of the exhaust gas is recirculated.
Low noise
The operational noise level of each unit has been
reduced to 60dB through the application of a double
vibration-isolating system using a liquid seal typeengine mount originally developed by MHI, optimized
design of the engine suction and exhaust system, andimproved cabinet noise-isolating performance.
Improvement of serviceability
A maintenance interval of as long as 5 years or

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Vienna Agreement,
Montreal Protocol

6.5
6.0

Newly
developed
unit

Kyoto Conference
on the Preventionof Global Warming

20%
increase inefficiency

COP

5.5
Second oil shock

5.0
4.5

HFC 134 a

4.0

HCFC 123

3.5

CFC 11

3.0
1970

1975

1980

1985

1990

1995

2000

2005

Fiscal year
Fig. 8 Trend of COP of electric motor driven turbo chillers

Fig. 7 External view of outdoor unitof gas engine heat pump typeair-conditioner

10 000 hours has been realized with the use of improved engine oil.
Fig. 7 shows an external view of an outdoor ECO-5
unit.
3.3 Large sized refrigerating machine
Typical large sized refrigerating machine products include electric motor driven turbo chillers, steam
absorption chillers, and district heating and coolingplants. The electric motor-driven turbo chillers are used
for the cooling of large-scale buildings, clean rooms in
IT plants, and district heating and cooling plants. The
NART series of electric driven turbo chillers realizes a
COP of 6.1, the highest efficiency rating in the world,
through the use of HFC134a refrigerant. As a result,the series contributes not only to reductions in CO2 emissions at electric power stations, but also to reductions inrunning costs. This machine was highly praised for its
high efficiency and was awarded the prize of the President of the Japan Machinery Federation in 2001. Fig. 8
shows the trend of COP levels for electric motor driven
turbo chillers. Fig. 9 shows an external view of a NART
turbo chiller.
In an effort to increase the capacity and efficiency of
steam absorption chillers, MHI has realized the world’s
largest absorption chiller with a capacity of 5000 RT anda steam consumption rate of 3.9 kg/h. RT. Using steam
generated by heat exhausted from a gas turbine used forcogeneration, the chiller in a district heating and cooling plant supplies chilled water to buildings in the area
served by the plant.
These chillers are controlled by a microcomputer control panel with a color liquid crystal display developed
originally by MHI. The microcomputer control panel isapplicable to various building systems such as
LonWorks (R), as an option, and can be used to control
the number of operating units so as to support the daily
operations of the customer. Furthermore, it can also beconnected to a “Hot Support” remote control system, sothat the chiller can be monitored 24 hours a day so thatMHI can offer suggestions on preventive methods andFig. 9 External view of turbo chiller (NART series)

prompt measures that can be taken to address any
troubles or difficulties in addition to advice on energysaving operation and planned maintenance.
MHI is currently constructing a district heating andcooling plant at the east entrance area of the Shinagawa
station. The plant will use a combination of an electricmotor driven turbo chiller and a steam absorption chillerthat fully utilize the advantages of MHI. An ice thermal
storage system using night electric power and gas turbine for cogeneration are to provide a stable supply ofchilled water at low cost to buildings such as offices andhotels in the area.
3.4 Automobile Air-conditioners
Automobile air-conditioners must be compact, because
the space in a car is limited due to the increase of onboard
devices such as audio sets and car navigators. At thesame time, the car air-conditioner must satisfy a variety of needs for improving comfort, saving power,
reducing fuel consumption, protecting the environment
through reduced use of refrigerants, and ensuring usersof further higher reliability and safety.
Accordingly, MHI is striving to improve the performance of the major components that constitute a car
air-conditioner in the following ways.
MHI has adopted scroll compressors from the past because they have the advantages of high efficiency, low
noise, low vibration, and high speed. As a result of various improvements, a new profile (stepped profile) has
been adopted, so that the performance and reliability of
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(a) Conventional
inner fin type tubes

Fig. 10 Profile of new scroll(stepped profile)(b) Dimple type tubes

Fig. 11 External view of evaporator plates

the scroll has been greatly increased as a result. Fig. 10shows an external view of the stepped profile of a scroll.
The excellent heat transfer performance and remarkable weight reductions in heat exchangers have beenrealized by providing numerous dimples on the surfaceof the refrigerant side of the tubes, instead of attaching
inner fins as has been the case until now, as well as by
optimizing the air side fins. In addition, in order to reduce the required space and amount of refrigerant
needed, the performance of the heat exchanger has been
improved (increased in density) and reduced in thick1 shows an external view of evaporator plates.
ness. Fig. 1
11
In the case of HVAC air-conditioning units, MHI intends to enhance the performance, reduce noise,minimize the size, prevent reheating due to the hot water heater, and optimize the arrangement of the heatexchangers, air paths, and damper to reduce pressure
loss. Power savings have been achieved by improving
the performance of the controller, without losing comfort in the cabin room.
MHI has also been successful in producing blowers ofhigh performance, high reliability, and low noise throughthe adoption of advanced blade profiles and rear edge
serration of the fan, and by optimizing the three-dimensional profile and operation points of blades by CFD and
FEM.
3.5 Refrigerating physical distribution systemequipment
3.5.1 Truck refrigeration units
The truck refrigeration units are divided into the direct-coupled type and sub-engine type, depending on themethod used to drive the compressor. The direct-coupled
type is used for compact and medium sized cars, while
the sub-engine type is often used for medium and large
sized vehicles. MHI provides a wide lineup covering allunits for light cars through large sized vehicles.
MHI takes great care to ensure observance with allenvironmental regulations such as those dealing withthe use of CFCs (chlorofluorocarbon), noise, and gas
emissions. With regards to the ban on the use of the
CFC family of refrigerants, for example, MHI has alreadyfinished replacing all CFCs and HCFCs with HFCs.
The improvement of the quality control of transported
food, changes in national dietary habits from home torestaurant, an increase in dependence on ready-madefoods, and the increase in the number of convenience
stores are accelerating the need for ever more effective
temperature controlled transport and storage environments. These include expansion of the light car market,
and the simultaneous transport of products in different
temperatures using multiple evaporator systems. MHI
has been very active in developing new products to meetthese needs.
MHI has developed the TUJ80D which is a combined
evaporator and condenser refrigeration unit using the subengine method, the first of its type in Japan. In this unit,
the evaporator and condenser are both contained together
in a single container, so that engine noise is reduced by
8dB compared with the noise level of conventional machines. The reduced noise reaches a level that permits
conversation in front of the power unit; that is, the TUJ80D
is a silent refrigeration unit that is also friendly to the environment. The refrigerant used for this unit is HFC404A,
which does not deplete the ozone layer. In addition, therefrigeration capacity of the unit has been increased by
10% over conventional units in order to accommodate theincrease in the size of car and truck bodies. Fig. 12 shows
an external view of the unit carried on a refrigeration truck.

Fig. 12 External view of truck refrigeration unit

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3.5.2 Marine refrigeration units
A marine refrigeration unit consists of a chiller unit used
to refrigerate a marine container. Hence, it needs to behighly reliable and durable enough to withstand such severe conditions as tropical zone, frozen regions, seawater,
vibration, and impact.
In particular, it has been recently advocated by somethat the durability of such units be increased further andthat the maintenance that is normally carried out periodically is to be abolished or minimized in order to reduce
operating costs.
The most critical issues regarding durability are corrosion of the compressors and air-cooled condensers used inocean circumstances. Accordingly, MHI has developed anew, original painting method which is known for its excellent corrosion resistance. Applying this newly developed
painting method, the operating lives of these machines havebeen extended by up to three times of that of conventional
units.
Backup functions, such as making emergency manual
operation possible in the event of failure of the controller
or refrigerant-regulating valve and transmitting operational data stored in the controller during voyages, havebeen fully completed as part of measures to increase reliability. Fig.13 shows an external view of a marine
refrigeration unit.

Fig. 13 External view of marine refrigeration unit

global warming through the reduction of CO2 emissions
caused by power generation. Based on its top priority on
developing high efficiency products, MHI is always striving to improve the efficiency of the refrigeration cycle aswell as of all major components such as compressors, heatexchangers, blowers, and inverters.
In the field of large sized chillers, MHI is working todevelop a steam absorption chiller that utilizes the exhaust heat of a gas turbine as well as utilize exhaust
heat directly from gas engines, as products that effectively use exhaust heat.
A suction gas-cooling system, commercialized by MHI
as a new product, is to be spread to the market. The
output of a gas turbine decreases as the air temperature increases in the summer. In order to compensate
for this decrease in gas turbine output, a suction gascooling system is used to cool the suction gas of the gas
turbine. This system uses chilled water that is supplied from an absorption chiller driven by steam
produced by the exhaust heat emitted by the gas turbine. In the field of thermal storage, MHI is planningto spread a PCM thermal storage system. In this system, heat can be storaged in high density at atemperature level that is equivalent to the extent towhich the temperature of the chilled water is higher
than ice (0oC). Both the suction gas-cooling and PCM
thermal storage systems can not only be installed in
newly built plants, but in existing plants, as well. Fig
Fig.. 14shows an external view of the first PCM thermal storage tank in the world installed at New Tokyo
International Airport.
(2) Use of natural refrigerants
At the third session of the Conference of the Parties to the United Nations Framework Convention on
Climate Change (i.e. the Kyoto Conference), six kindsof gases including HFCs were defined as being greenhouse gases. Accordingly, MHI has moved toaccelerate the commercialization of products using
natural refrigerants that have little, if any, greenhouse effect.

4. Future
The subjects to be considered and products to be targeted in the future are described as follows:
4.1 Protection of global environment
It is the basic policy of MHI to place top priority on protection of the global environment. In this regard, converting
the CFC and HCFC family of refrigerants to HFC refrigerants, increasing efficiency, utilizing natural refrigerants
as a means of preventing global warming, and accelerating the recycling of waste materials including the recoveryof refrigerants upon the repair and scrapping of refrigeration equipment are all issues of vital importance to MHI.
4.1.1 Protection of the ozone layer
The depletion of the ozone layer has become an environmental problem of great international concern. This
led to the conclusion of the Montreal Protocol to protect
the ozone layer in 1987. As a result, the production anduse of CFC and HCFC refrigerants became restricted. MHI
intends to accelerate the conversion of conventional refrigerants to HFC refrigerants that do not deplete the ozone
layer, and to complete this conversion before the international deadline for scheduled complete restriction.
4.1.2 Prevention of global warming(1) Increasing efficiency and saving energy
It is the intent of MHI to further improve the energy
saving performance of room and packaged air-conditioners in order to reduce power consumption. One result of
these efforts is the contribution thus made to preventing

Mitsubishi Heavy Industries, Ltd.
Technical Review Vol.40 No.1 (Feb. 2003)

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Fig. 15 External view of CO2 compressor
Fig. 14 PCM heat accumulator installed at New
Tokyo International
AirportFig. 16 Test car for CO2 system

environmentally oriented designs. This might include
extending product life, pursuing resource-saving effects
through reductions in product sizes and weights, finding ways to facilitate easy separation and disassembly,
reducing the numbers of kinds of plastics, and using recycled materials.
In the field of room air-conditioners, MHI has alreadyachieved a level that far exceeds the standard recycle
rate specified by Law for Recycling of Specified Kinds ofConsumer Electric Goods that came into force in April
2001. Even so, the company is continually seeking ways
to extend the recycling concept to all cooling and heating products that it produces.
4.2 Utilization of IT (Information Technology)
With the great progress in IT that has been seen inrecent years, the use of IT is accelerating ever more
quickly in both business and ordinary households as theinfrastructures for high-speed networks are built andcome on line. MHI is looking to be the first commercialize internet-based air-conditioners for households, andintends to apply intelligent system design to the management of buildings for business purposes. As a result,energy-savings and serviceability will be improved
through the use of remote monitoring, control and diagnosis of the states of the air-conditioning systems andequipment used by users.
4.2.1 Energy-savings
The internet-based air-conditioner known as “e-@ir”
can control a maximum of 255 sets of air-conditioners
through wireless communication between a personal
computer and the respective air-conditioners. As a result, multiple air-conditioners in houses, as well as indormitories, schools, and companies can be easily andconveniently controlled. The internet air-conditioner canbe switched on or off, and room temperature, humidity,
and external temperatures can also be monitored. Required temperatures can be set from a long distanceaway, so that forgetting to switch the system off or excessive cooling or heating can be prevented no matter
where the user is. Moreover, each air-conditioner in ahouse will be connected in the future to the internet via
a personal computer in the house. This will make on-

MHI’s experience with automobile air-conditioners
shows good prospects that efficiencies can be increased
and the weight of heat exchangers and compressors
can be decreased even when carbon dioxide is used asa refrigerant. As a result of practical car testing on
this prospect, it has been confirmed that a car airconditioner using carbon dioxide has a refrigerating
capability equivalent to a system using HFC134a.
Fig
Fig.. 15 shows an external view of CO2 compressor and
Fig
Fig.. 16 a test car for CO2 system.
In addition, MHI intends to develop an electric motor driven turbo chiller in which ammonia is adopted
as a refrigerant in large sized chillers. Current technology for improving efficiency will also be
incorporated in the system.
(3) Leveling of electric power demand
Another goal of MHI is to increase the performanceof a packaged air-conditioner provided with an ice
thermal storage and a chilling unit provided with an
ice thermal storage even further. This would solve
problems due to peak demand for cooling at midsummer by using electric power that is stored during thenight. In addition, MHI is planning to propose optimum air-conditioning systems with improved
efficiencies for a given requested condition for gas airconditioning systems (gas heat pump typeair-conditioners and gas absorption chillers) that do
not consume electric power.
Utilizing its advantage as an all-round air-conditioner manufacturer, MHI always strives to propose
the best choices to its customers and clients. For instance, a gas type air-conditioning system might be
the best choice for a school that has limited electric
power source capacity, while an ice thermal storage
air-conditioning system might be optimal for a factory that is ISO 14001 certified.
4.1.3 Recycling recovered waste material
In order to control the amount of waste and save limited global resources, MHI consistently strives to develop

Mitsubishi Heavy Industries, Ltd.
Technical Review Vol.40 No.1 (Feb. 2003)

9Building management computer

Communication device
corresponding to BACnet

Communication device
corresponding to Lon Works R

MHI's "Superlink" air-conditioning control network

Multi-packaged
air-conditioner

Gas heatpump typeair-conditioner

Ice thermal
storage typeair-conditioner

For store

For plant orother large facility

MHI packaged air-conditioner for buildings
Fig. 17 Scheme of MHI's plan for the opening its packaged air-conditioner system

Material,
structure,strength, etc.

Ergonomics

Design. Basic performance. Operation part,
External appearance. Modeling of feeling and sensibility. Environmental control,. Operability, controllability, human error

Design of productair-conditioner

Mechanism. Function. Performance. System

Grasping humancharacteristics

Indicator. Information element(meter, lamp, image,sound). Environmental element(vibration, noise, heat)

Receptors. Senses (five senses). Combined senses

Effectors
Operating parts
Product. Hand, foot, finger. Voice

Lever, switch, keyboard

Judgment. Recognition. Sensibility. Reaction

Human

Fig. 18 Position of ergonomics

demand control such as changing the set temperatureor temporarily stopping the system during power peaks
in midsummer possible by monitoring the extent of power
consumption from a great distance. Thus, the energysaving effect of utilizing IT is expected to be significant.
4.2.2 Improvement of serviceability
MHI was the first company to develop an air-conditioning control network known as “Superlink” for abuilding management system, which is capable of controlling several ten sets of indoor and outdoor units. In
addition, the opening of communication protocols, as
represented by LonWorks (R) and BACnet, for building
management has been spreading recently. This network
can communicate with building management systems
that are connected among different venders. In fact, thetrend now is towards achieving overall management of
not just the interior of a specific building, but also to
expanding such control to provide consistent management over several buildings at the same time. District

control based on this approach has even begun to app e a r r e c e n t l y. M H I h a s a l r e a d y d e v e l o p e dcommunication devices that correspond to both
LonWorks(R) and BACnet, in order to accommodate therealization of intelligent building management systems.
Fig. 17 shows a MHI plan for opening such a system
based on its packaged air-conditioning system.
Based on these experiences, MHI is striving to improve its services and solve defects and faults quickly
through the operation monitoring system known as QSSnet (Quickly Service Support System network). As an
all-round air-conditioner manufacturer, MHI is accelerating the pace of completion of networks for use in remotemonitoring systems, fault prevention systems, and thelike with the ultimate goal of achieving the complete satisfaction of its customers of both software and hardware
products and services.
4.3 Improvement of usability
ISO13407, “Human-Oriented Design of Interactive
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Technical Review Vol.40 No.1 (Feb. 2003)

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Subject of study
Understanding
human and its society
Understanding
interaction between
human and machine
Understanding
human itself

Feeling andconsciousness

Expanding the areaof human science

Recognition
and action
Senses andpsychology
Physiological characteristics
and various functions
Characteristics
of human body

Development of
human-oriented
technology

Needs

Relaxation
Self
Convenience
Healthandexpression
and comfort
andabundance
safetyFig. 19 Development of ergonomics

Clarificationof functions

Systems,” was established in June 1999 as an international standard. MHI has striven to improve the designof all new air-conditioners in keeping with the principlesof this standard, continuing its tradition of placing major emphasis on both performance and reliability. This
being said, however, usability will become an ever more
important subject of concern in the future, as well.
The marketability of MHI air-conditioner products has
continued to improve, as human technology is applied
more and more in their development and design fromFig
the perspective of comfort and ease of use (Fig
Fig.. 18
18). In
the future, as can be seen in Fig
Fig.. 19
19, MHI intends to extend such ergonomics even further from the viewpointof customer ’s needs. This will include contributing to
the progress of air-conditioning systems by introducing
new functions and further facilitating ease of use. Particular attention will be placed on the following points
in these efforts:
Usability will become an ever more important to customers as a selection factor, complaint factor, anddifferentiation factor from other competitive products.
Easy use is becoming ever more strongly expected byusers.
Consideration needs to be given to convenience, suitability, for and ease of use by aged and disabled
persons.

part of the social infrastructure, air-conditioning systems
will inevitably become more important as a means ofimproving the comfort of living spaces. Related systems
will also become increasingly essential to both freezing
and refrigerating storage that is closely related to food
distribution. Both these areas promise significant
growth as important markets in the future.
Protecting the irreplaceable global environment andgrasping customer’s needs exactly, MHI is continually
striving to provide equipment and services to the market that delight customers and satisfy their needs
completely. To this end, the company is actively conducting research and development and is always seeking
ways to improve the quality of its services ever further.
In the future, MHI will also strive to contribute to
the creation of an abundant and comfortable human life
throughout the world, with an extensive product mix
ranging from local air-conditioners through to district
heating and cooling systems. Understanding the intention of MHI, the authors would like to express theirappreciation to all interested parties for their further
guidance to and support of MHI in these activities.

.
.
.

AIR-CONDITIONING & REFRIGERATION SYSTEMS HEADQUARTERS

5. Conclusion

Managing Director,
General Manager,
Air-Conditioning &Refrigeration Systems Headquarters

This article presented a summary introduction to thepast, present, and future of heating and cooling products of the air-conditioning and refrigeration systembusiness of MHI.
The market of air-conditioning and refrigeration systems is extremely large. Moreover, the market is a field
in which future growth is expected. In particular, a highGDP (Gross Domestic Product) rate is expected in Asia
because its population is large and the economy is growing, overall. As houses and buildings are completed as

Hirooki Shibanai

Genjiro Kimura

Hisashi Hattori

Takashi Kawakami

Mitsubishi Heavy Industries, Ltd.
Technical Review Vol.40 No.1 (Feb. 2003)

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