Department of Biomedical Engineering
Ryan Peters
Department of Biology
Malavika Kesavan
Department of Astronomy
Elizabeth Palmer
Industrial Design
Calvin Tabor
Scott Dailey
Clean Cool: The Next Iteration of Green Refrigeration
Overview
Clean Cool represents the next iteration of green refrigeration. Our project goals were to select a
greener insulation and develop an innovative design while maintaining the device's affordability in order
to promote consumer adoption.
Introduction
The unity of wants and needs are essential to the functionality and progression of society. Over
time food has evolved into a central component of modern cultures. With the invention of the modern
commercial refrigerator in 1911 by General Electric and its subsequent mass production in the decades
that followed, the way we store and consume food was revolutionized.1 The cultural norm of a daily trip
to the market or the daily delivery of milk to the doorstep no longer exists in modern America. While the
increasingly expanding population has experienced an explosion of new technologies over the past few
decades, the refrigerator remains a constant in the American home. 99.9% of the 130 million
households in the United States currently own a refrigerator, with 17% of these households owning two
or more.2 In this light, the refrigerator may symbolize the modernization of society and the vast increase
in our standard of living over the past century. However, like any developing technology there exist
flaws and negative, unintended consequences.
In particular, the modern refrigerator has had a harmful impact on the environment. The growth
of our population and advancements in technology over the past century has started to deplete the
ZRUOG¶VQDWXUDOUHVRXUFHVThere has been a recent effort to find advancements in technology that not
only expand function, but also minimize their effects on the environment. Refrigerators are the second
largest consumer of electricity in the average US home3, consuming between 450-850 kWh with a
yearly cost of $51.80-$97.84 (average cost of residential electricity in the US is $0.1151/ kWh).4 This
means that each refrigerator releases 1500 lbs of CO2, a greenhouse gas that has been attributed to
global warming and other harmful effects on the environment. All of the consumer refrigerators in the
United States alone release a combined 114 million tons of CO2 per year. Therefore, while the cost of
operating a modern refrigerator may seem minimal, the overall impact on the environment is significant.
Public opinion in the US strongly agrees with these sentiments, with 91% of respondents
believing that it is important to protect the environment from the effects of energy consumption.
However, 94% of respondents also believe it is important to keep energy costs low.5 The refrigerator is
a perfect device to address these concerns because of its wide reach. By increasing the efficiency of
the modern refrigerator, we provide the function we as a society have grown accustomed to
experiencing, DVZHOODVORZHULQJHQHUJ\FRVWVDQGWKHSURGXFW¶VRYHUDOOHQYLURQPHQWDOLPSDFWV
The need for energy conservation is not a new concern. The US government has recognized
the need to decrease our energy consumption and has enacted several recent pieces of legislation.
The Appliance and Equipment Energy Efficiency Standard Act of 2005 provided energy tax incentives
and updated the efficiency standards of the National Appliance Energy Conservation Act of 1987. 6
Energy Star is a government program that awards special certification to appliances that are 30% more
efficient than government standards. In addition, both the American Recovery and Reinvestment Act of
1
Auburn University; http://www.industrialdesignhistory.com/node/148
Department of Energy; http://www.eia.doe.gov/emeu/reps/enduse/er01_us.html
3
Department of Energy; http://www.eia.doe.gov/energyexplained/
4
Department of Energy; http://www.eia.gov/cneaf/electricity/epa/epaxlfile7_4.pdf
5
State of Virginia: Energy Division; http://www.dmme.virginia.gov/DE/RelatedProgs/energystar.shtml
6
State of New York; http://www.dec.ny.gov/environmentdec/19124.html
2
2009 and Cash for Appliances offered rebates to trade in old, inefficient appliances such as
refrigerators for newer, more energy efficient models.7
The average lifespan of a refrigerator is 13 years.8 The Department of Energy suggests buying
a new refrigerator once this time period has passed because the efficiency decreases significantly
afterwards.9 This decline in energy efficiency is strongly affected by the insulation. Insulation for
refrigerators is usually a loose-blow fill polystyrene derivative and over time this settles toward the
bottom, decreasing its effectiveness. In addition, a major problem with refrigerator insulation is water
leakage. Over time, moisture leaks into the compartment containing the insulation, causing a
degradation of the material. Finally, there is currently no standardized way to safely dispose of
insulation since many of them are treated with flame retardants and other chemicals that are harmful to
the environment.10
Many of these concerns such as carbon footprint, energy efficiency, and insulation can be
addressed with modifications to the overall design and selection of a new insulation material. Taking
RXULQWXLWLYHJUDVSRIZKHUHHQHUJ\HIILFLHQF\FRXOGEHLPSURYHGDQGEDVHGRQRXUJURXS¶VEDFNJURXQG
and interests, we developed a two-pronged approach for refrigerator innovation. First, we examined the
material used to insulate the refrigerator. In our research, we found that a common household sponge
can surprisingly act as an efficient and cost-effective insulator. Second, we re-examined the life cycle of
the refrigerator which led to an innovative design that incoUSRUDWHVWKH³W\SLFDO$PHULFDQOLIH´EXWFDQ
also be marketed globally.
Background: Refrigeration
Refrigeration is the process of transferring heat from a low-temperature environment to a hightemperature environment. This is against the thermodynamic gradient and therefore needs an energy
input to occur. Refrigerators require a working fluid called refrigerant which is used in the refrigeration
cycle. The most common refrigeration cycle is the vapor-compression refrigeration cycle. The
refrigerant enters as a vapor into the compressor and is compressed further, causing the compressor to
increase in temperature. As the compressor is cooled, the refrigerant condenses and flows down the
coils of the condenser into the capillary tube. In the capillary tube, the pressure and temperature drop
significantly, and the cold refrigerant enters the evaporator where it absorbs heat from the interior of the
refrigerator and turns back into a vapor, thus completing the cycle.11 It was decided to keep the basics
of this design because any modifications would have been beyond the scope of our project goals.
However, there are many components in this system that are already being targeted in other
development projects such as the cooling system and internal temperature control.
Insulation
7
Department of Energy; http://www.energysavers.gov/financial/70020.html
National Association of Home Builders; http://www.nahb.org/fileUpload_details.aspx?contentID=99359
9
Department of Energy; http://www.energysavers.gov/your_home/appliances/index.cfm/mytopic=10020
10
Jacob, James W.; Methods of insulating refrigerator cabinets and other insulting spaces; October 30, 1962; No.
234,085
11
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8
Background
:LWKWKHDLPWRDOOHYLDWHDUHIULJHUDWRU¶VLPSDFWRQWKHHQYLURQPHQWRQHRIRXUSULPDU\FRQFHUQV
is its insulation. This vital component is responsible for preventing heat from entering the colder interior
of the refrigeraWRU DQG WKXV GLFWDWHV LQ ODUJH SDUW D UHIULJHUDWRU¶V HQHUJ\ HIILFLHQF\ WKURXJKRXW LWV
lifespan. Among most common insulation currently used in a refrigerator are made of polyisocyanurate
or polystyrene foam (Dynblast).12 Both have a low specific heat capacity, low thermal conductivity
(defined as the inverse of thermal resistance), and a low density, all properties desired in an insulator.
However, these materials also have a high carbon footprint and can be damaging to the health of both
humans and animals, as well as the environment. Cellulose is an alternate material that has similar
properties, but does not have the same environmental damage and a reduced potential for adverse
health effects. Even so, there are still problems with cellulose insulation including flammability, the
potential for pests, and thermal resistance. To decrease the chance of flammability we can add
powdered borax in ratio of 1:3.13 It is unlikely that pests would be an issue in this situation considering
that the insulation will be placed in a vacuum tight area.
In order to help evaluate the selection of cellulose against other leading insulators, we contacted
material scientists Drs. Marsha Bischel and Amy Campbell from Armstrong, a manufacturer of flooring,
ceiling and cabinet products (as referred by Dr. James Cawley from the Department of Materials
Science and Engineering). They deal commonly with insulation used in walls and ceilings and provided
useful insight in a shared conversation. According to them, one of the strongest competitors among
³JUHHQ´ LQVXODWRUV are soy-based Spray Polyurethane Foams (SPF) which are often used with
environmentally harmful isocyanates. However, research indicates that only a maximum of 15% of the
foam is actually soy-based, and the rest is petroleum-based which leads to a large amount of marketing
hype.14 Perhaps their most pressing point however when considering environmental impact is the
toxicity of materials used to prevent flammability. Insulating materials are duly treated to prevent fires in
EXLOGLQJVDQGKRXVHVEXWDWWKHHQGRIDUHIULJHUDWRU¶VOLIHWKHFKHPLFDOVZLWKLQWKHLQVXODWLRQPDNHVIRU
dangerous and toxic disposal during the decomposition phase at a landfill.15
Because our overall product would also be concerned with energy efficiency throughout its
lifespan, Drs. Bischel and Campbell pointed out that our primary concerns ought to be with respect the
entire lifecycle of the refrigerator (from manufacture through its entire usage), rather than just
attempting to improve energy expenses solely at the manufacturing stage. The energy efficiency during
WKH UHIULJHUDWRU¶V ORQJ OLIH RI RSHUDWLRQ DQG XVDJH IDU RXWZHLJKs the small time and energy expended
during manufacture. With that focus in mind, a refrigerator insulation that, for example, starts with a
given resistivity to heat flow and holds that strength after 50 years is much more preferred than one that
starts with a stronger resistance but worsens greatly over that same time period. Energy consumption
therefore depends heavily on how well the refrigerator is insulated during its lifespan.
12
American Chemistry Council; http://www.polyurethane.org/s_api/sec.asp?CID=903&DID=3616
(Cellulose Plant and Process)
14
Spray Foam; http://www.sprayfoam.com/npps/story.cfm?nppage=187
15
Environmental Protection Agency; http://www.epa.gov/dfe/spf_presentation_2009_epa_osha_niosh_cpsc.pdf
13
Next, we aimed to gain insight from a current refrigerator producer and were fortunate to speak
directly with Scott Shaver, a household appliances and refrigerator manufacturing manager from
General Electric (GE). Supporting our conversation with the scientists from Armstrong, he explained
that a selection of blowing agents exist that can be used in the process of inserting insulators into the
shell of a refrigerator (a standardized manufacturing procedure, which all use spray-in foam). The
blowing agents range from historically freon (CFCs, SKDVHG RXW LQ WKH ¶V due to environmental
concerns) to some use of hydrochlorofluorocarbons (HCFCs, also contain harmful effects to the ozone,
being phased out by 2020 per the Montreal Protocol implemented through the U.S. Clean Air Act) 16, to
the more modern use of cyclopentane (much more friendly for the atmosphere since he explains it is
heavier than air, however must be disposed of properly to avoid entering a landfill). GE currently has
partnered with the EPA to implement the Appliance Recycling Centers of America (ARCA) method to
recover 95% of insulating foam found in refrigerators, in order to capture these toxins and greenhouse
gases from leaking into the atmosphere.17 :KHQ DVNHG DERXW FRQVLGHULQJ ³JUHHQHU´ LQVXODWLRQ WKH
manager pointed out that with foam insulation, energy efficiency is very high. Given the same lifecycle
energy concerns as described by the scientists from Armstrong, he also prioritized the strength of the
insulator with its impact on energy usage during the lifespan of the refrigerator. According to GE
manager, any switch away from current insulators such as polyurethane must satisfy three main
parameters: (1) customer demand for as large amount of space within the refrigerator as possible (i.e.
the thinner the insulator can be to remain just as effective, the better), (2) federal and customer demand
IRUHQHUJ\HIILFLHQF\WREH³JUHHQHU´DQGFXVWRPHUGHPDQGIRUDIIRUGDELOLW\
Analytical Assessment
Following the notion of innovative use of preexisting materials, we further narrowed our
selection to cellulose sponge; LWVXSSRUWVRXU³JUHHQ´SULRULWLHVIRULWVKLJKUHF\FOHGFRQWHQWZKLOHDOVR
bearing pockets for air that would make it a good insulator. Prioritizing the major concerns about
refrigerator insulation described by Drs. Bischel and Campbell from Armstrong, as well as the insights
gained in our own research, we began an analysis of our selection. As previously described, the
desired characteristics for an insulator are to carry a low heat transfer, low specific heat capacity, low
conductivity and high R-value (thermal resistance), values not yet detailed for our material.
Initially, to test the feasibility of cellulose the sponge as an insulator, a qualitative experiment
was performed in order to demonstrate that our choice of material is comparable to commonly used
insulation. In order to test this, a wooden box with a removable lid was constructed with the dimensions
14.5cm x 14.5cm x 14.5cm, with the wood walls 1.8cm thick. A smaller box, composed entirely of the
selected insulation, was constructed with the dimensions 10cm x 10cm x10cm, with the insulation walls
1.7cm thick. The smaller insulation box was lined with plastic (Ziploc bags) which was then placed in
the larger wooden box. The large wooden box was sealed, ¾ cup boiling water (100º C) was poured
into the container, and a thermometer (with a stopper) was placed through a sealed hole in the top to
measure the temperature over time. This process was performed with cellulose sponge, Styrofoam
(polystyrene), pink housing insulation, and a control trial consisting of no insulation. Typical insulation
16
17
Penton Media; http://contractingbusiness.com/columnists/cb_imp_5837/
The Fast Company; http://www.fastcompany.com/1725706/ge-epa-team-up-to-slash-appliance-landfill-waste
used in refrigerators is the loose blow-in fill which is generally a form of polystyrene. Given that
Styrofoam consists of polystyrene and contains similar insulative properties, we took that material to be
a fair comparison to current refrigerator insulation.
Figure 1 shows the results of our experiment to compare insulation cooling rates.
Measurements for all of the trials were started at 75º C in order to produce standardized results that
can be effectively compared. The control trial (no insulation) cooled much faster than those with
insulation which is to be expected. However, the Cellulose sponge, Styrofoam, and Pink Insulation all
performed fairly closely, with the styrofoam performing the best (defined as the longest time to drop in
temperature) followed by the cellulose and then the pink insulation. Therefore, this proves in our
qualitative experiment that the cellulose sponge is on par with current insulators.
While we have proved qualitatively that the cellulose sponge is comparable to current insulation,
since cellulose sponge is not already used as an insulator, quantitative assessment has proved difficult.
Material specifications, as provided by the sponge manufacturer 3M, unfortunately did not detail its
thermal properties for this reason. Similarly, the materials database18 used by professionals on campus
also lacked information for a sponge form of cellulose. At the suggestion of Dr. David Schiraldi from the
Department of Macromolecular Science and Engineering, our next step was to contact the laboratory
on campus capable of performing such tests. Testing was available for late February and successfully
18
CES EduPack 2010 (Access granted by Dr. DeGuire)
scheduled, but due to unforeseeable complications within the laboratory group itself, at the last minute
this option became unavailable prior to early May.
Despite these setbacks, we were able to estimate the thermal properties of our cellulose sponge
to fall within a range of typical values for other cellulose-based insulators (see Table 1). Upholding our
SULPDU\ REMHFWLYH WR XVH D ³JUHHQHU´ LQVXODWLRQ LQ DGGLWLRQ WR DQ LQQRYDWLYH GHVLJQ WKH XVH RI D
cellulose-based product remains a key component for our refrigeration design. Perhaps one of the
strongest arguments against a sponge insulator is its natural tendency to attract moisture which can
significantly affect insulation effectiveness, so in response this necessitates the use of a vacuum seal
(namely a Mylar bag). Mylar is the common name for BoPET (Biaxially-oriented polythylene
terephthalate) and is known to have good barrier properties. It is readily available for ordering in a
variety of sizes as well as properties (some have aluminum coating to reflect heat). It is not currently
used in refrigerators, but is used in some housing situations, electrical insulation, and a variety of other
ways including fire resistant blankets.19
One point to note from Table 1 is the avoidance of using a vacuum seal for insulation even
though the R value is significantly higher than the other insulator options. This is due primarily to the
fact that it is impossible to get a perfect vacuum seal which would decrease the true effectiveness of
the insulator. When speaking with Scott Shaver of GE, he mentioned that the equipment involved would
be expensive as they would need to reach a pressure level of 10-5 Torr. In addition, the time to make
one seal would take 3-4 minutes which would slow down the entire mass production process. Though
this cost will be higher, the product will be viable for a longer period of time providing much higher
energy savings and a lower environmental impact due to life cycle.
Polyisocyanurate also appears to be at first glance a strong candidate for a material due to its
high recycled content. However, the main drawback is that polyisocyanurate is very flammable and
releases toxic elements into the environment. In addition, polyisocyanurate is more difficult to recycle
than other insulations such as polystyrene, reducing the green appeal for its entire life cycle.20
Table 1: Insulator Comparison18
Material
R-Value
(m^2*K/W*in)
% Recycled
Material
Commonly Used
Chemicals in
Manufacturing
Manufacturing
Carbon Footprint
Expanded
Polystyrene
Foam (XPS)
5.0
--
--
3.42-3.78 lb/lb
Cellulose Loose
Fill
3.7
75%-85%
Some Borate is
needed (flame
retardant)
1.25-1.35 lb/lb
Pink Housing
4.5-5.0
--
--
3.5-4 lb/lb
19
20
Plastics; http://www.grafixplastics.com/mylar_apps.asp
Air Quality Sciences; http://www.aerias.org/DesktopModules/ArticleDetail.aspx?articleId=95
Insulation
Fiberglass
2.5-3.7
Max 30%
Uses
formaldehyde
based glue
Cellulose wet
spray
3.4
75%-85%
Some Borate is
needed as a
flame retardant
Polyisocyanurate
4.3-8.3
Up to 100%21
trischloropropylphosphate
(TCPP)
Cellulose
Sponge
Estimated ~4.5
75%-85%
Consider using
Borate
1.25-1.35 lb/lb
Vacuum seal
30-50
--
< 1 lb/lb
1.25-1.35 lb/lb
DESIGN
The Development of the Concept
When considering how to redesign the refrigerator itself, we decided to focus on the aesthetic
appeal of a simple external shape. The design should appear sophisticated, visually agreeable with a
variety of kitchen styles and be easy to manufacture. Throughout the concept development stages, we
continued to prioritize simplicity and ease of use, rethinking unnecessary functions and adding features
that would enhance the performance to make it more user-friendly. In our first drawings of the designs,
we considered stackable units, a variety of orientations and sizes, and compartmentalization of the
refrigerator in order to increase energy efficiency and reduce wasted space. As these ideas matured,
we maintained concepts that were most central to our mission of increasing energy efficiency by
improving the way users interact with the refrigerator and how it operates. The refinement stage began
by combining these ideas into a single design.
Refining the Concept
7KH ILUVW VWDJH RI UHILQHPHQW FRQFHUQHGPRGXODULW\ DQG VSDFH FRQVHUYDWLRQ $ ³JURZ-with-PH´
concept was devHORSHG OHDGLQJ WR D PRGXODU ³PLQL-IULGJH´ GHVLJQ VWDQGLQJ WZHQW\-eight inches tall.
Ideally, young adults would purchase a single unit for dormitory style or other group living arrangement
early in life, and be able to add onto it with another unit or freezer later in life, rather than purchasing a
new full-size refrigerator. This would save the customer money, conserve resources by adding onto the
previous refrigerator rather than replacing it, and create repeat business for retailers who sell the unit.
21
American Chemistry Council; http://www.polyurethane.org/s_api/sec.asp?CID=903&DID=3616
Several additions were made to the initial concept. To help save energy beyond the insulation
choice, we integrated shelves that allow users to seal off unused areas of their refrigerator. More userfriendly additions included proposing a piggy-back power system allowing the top unit in a stack to plug
into the one below it, sourcing power from one cord plugged into a single outlet. We also added a light
to the inside of the handle to make the refrigerator easier to find for late night snackers.
Consolidation of Ideas and Incorporation of User Input
In the semi-final round of the competition we were encouraged to investigate several changes
that would further improve how users interact with the product as well as suggestions to make our
product more feasible, sustainable, and energy efficient. Affordability, efficiency and the maximization
of interior space were put at highest priority. The following renderings show the model in its final form,
displaying the glass door concept, the sealing capability of the shelves, and the general interior.
Regarding the external design, the outer skin of each unit can differ depending on the tastes of
the market in which it is sold. The skins could possibly be produced locally in their respective markets,
using locally appropriate materials and processes. This means not all refrigerators will have a metal
skin. There are already many refrigerators on the market today that do not. Some high-end full-size
refrigerators have a wood covering to match the cabinets in kitchens, but this means families who use
their refrigerators as a message board would not be able to use magnets on it, and may be turned off.
Our solution to this problem is that any optional non-metal skins for our refrigerator will have magnets
embedded in the back of the skin to maintain this useful and expected feature.
From a design and engineering standpoint, we were encouraged to look at designing for
disassembly. In order to understand the issues associated with disassembling a refrigerator as they are
currently manufactured, we took one apart. From the process and our background research, traditional
refrigerators are not only difficult to take apart but very difficult to recycle. The metal shell for example,
was attached to the back of the machine with adhesive and the insulation had been reaction injection
molded into the void between it and the inner plastic shell. The insulation was fused to the outer metal
skin, and the condenser coils buried in the insulation foam, making this more difficult to separate
without appropriate machinery or chemicals. With this experience fresh in our minds, we set out to
make material separation in our refrigerator much easier at the end of its usable life. Our shell is made
entirely of one type of plastic for ease of recycling. Additionally, the condenser coils are separate from
the insulation making them easier to remove. Finally, a retractable cord, power supply, and circuitry are
all contained in a metal box on the rear of the unit for easy removal during disassembly, or
replacement.
Luckily, sticking with a simple, elegant, confident shape makes cleaning very easy. The smooth
straight sides and rounded edges of each unit leave very few crevices for built-up dirt and grease to
hide, and because the exterior is completely sealed off to keep the insulation dry, the entire unit can be
sprayed off if need be. The plastic interior is easy to clean, and even if a wood shell was selected, the
whole unit is no more difficult to maintain than a kitchen table. Furthermore, the shelves can be easily
removed and washed in a kitchen sink, and the interior is waterproof sealed as well.
We also considered a feasible solution to an earlier concept of using a glass door that allowed
XVHUVWR³EURZVH´WKHFRQWHQWVRIWKHLUUHIULJHUDWRUZLWKRXWOHWWLQJWKHFRRODLURXWDQGZDVWLQJHQHUJ\
The initial concern was that energy would be slowly lost through the glass itself, not a strong insulator.
The solution we came to is similar to a screen door. We simply integrated a glass door into the
insulated door, sharing a common hinge so that users can open one or both depending on their need.
For example, if the user is taking inventory of their refrigerator before a grocery run, they can browse
without letting cool air escape. Our innovation will help reduce the energy loss created by this habit.
Finding a home for the freezer was our next mission. We had played with the idea of making the
freezer another modular piece that could fit on top of the refrigerator, but decided instead to include one
in each of the units. This way, a two-unit system is comparable to a full size refrigerator in terms of
freezer capacity without the need to add another unit. Additionally, the full-size configuration will only
use two compressors, like their traditional full-size refrigerator counterparts, rather than the three that
would be needed to add a separate freezer. Finally, the individual units needed to be around thirty-two
inches in height to be compatible with European under-counter applications and comparable to U.S.
mini-fridges. If two of these units were stacked, a freezer would be above an acceptable use height.
Including a freezer section in each unit makes them a more complete product individually, and allows
them to fit common placements in both Europe and the United States.
Regarding modularity and spacing, stacking two units requires a way to secure them to one
another. Our solution uses four feet located at the corner of each unit that slide-lock into corresponding
spaces on the top of every unit. In a full-size scenario where the units would need to be stacked and
locked, the back would likely be facing a wall like most full-size refrigerators do. This means they would
have to be pulled away from the wall to be stacked and un-stacked, eliminating the possibility that they
unintentionally become unattached.
MARKETING
With such a versatile design, our final product could be easily adapted to many living situations
and tastes with little modification. The appeal of the Clean Cool refrigerator is that it gives more
consumer options in terms of look and size, saves consumers money on energy bills in the long term,
and does not compromise functionality when ready to upgrade to a larger refrigerator. A consumer
needs only to add another module.
To further gain user input on the use of refrigerators, we conducted a brief survey consisting of
four columns, as quoted from the survey itself:
1. Just Getting (or restocking) ± ³you know what you want to take out (or put in) the fridge and
you spent no time browsing´
2. Just Looking ± ³well, you browsed the fridge but you didn't see what you wanted´
3. Looking and Getting ± ³success! you started browsing the fridge, and lo and behold, you
found something you wanted´
4. Date and Time ± ³pretty straightforward, MM/DD and HH:MM´ (allowing for averaging over
days)
It was found that in a sorority dorm, with 30 girls and two normal refrigerators, that each was
opened approximately 20 times a day over 5 days. More than half the time this action involved looking
around the refrigerator before grabbing food (if anything). When considering two typical non-collegestudent households, refrigerators were opened about 20-25 times a day during the days individuals
spent most often at home, with about 2 of those times spent looking, according to our sample group.
However, in speaking with other families it is apparent that looking to check the levels of groceries and
what leftovers are available are highly ranked on the list of reasons why their refrigerator is open. The
glass door design component would appease both such clientele then, for this reason.
From mini-fridge information and general understanding of college student life, if you have a
small refrigerator, you typically know exactly what goes in there since it is such a small personal space.
There is no need to "look around" because one usually remembers what little he keeps there. Hence
very little time and energy, if any, is spent browsing.
We also broadened our scope from the domestic market to the inclusion of international
markets. Our final design is of a height compatible with European under-counter applications,
comparable to traditional mini-fridge sizes in the U.S., and when stacked, comparable to U.S. full-size
refrigerators as well. The resulting universal core can serve international markets without modification.
Furthermore, the pURGXFW¶V GHVLJQ-for-GLVDVVHPEO\ FRQVLGHUDWLRQV ZLOO KHOS LW PHHW (XURSH¶V PRUH
rigorous recycling standards in addition to the upcoming Energy Star 2014 standards in the United
States.
Just as notable, there appears an equal opportunity for presence in the Asian market. While in
Europe a major constraint is space, rolling blackouts and unreliable power are more frequent in Asia.
More and more people are moving from pre-industrial to industrial lifestyles and with this comes with a
greater access to food and drink that needs to be stored. However, since infrastructure lags behind
population expansion and upward mobility, many times electricity is only available for a portion of the
day or unreliable. In places such as this (parts of Asia and even some European countries like
Armenia), it would be advantageous to have a refrigerator that better maintains temperature to prevent
spoilage, reducing costs as well as illness. This was apparent when we spoke with two different families
from India. Both were small business owners (one of textiles and another of a health clinic) and both
stated that this would benefit them on the condition that the refrigerator is on par with the cost of the
average refrigerator.
Further support for its global appeal is the customization of the units. In addition to size choice
because of its modularity, the outer skin can be tailored to the tastes of many customers. Changes in
color, texture, pattern, material, and general shape can be made quickly and inexpensively in
production to address trends and locations. For example, it carries the potential to offer a "local" feel ±
skins made of the product of the country, such as bamboo in the Chinese market.
Since our product is most tailored to the middle class, and consumers looking to lessen their
impact on the environment, this applies to a large subset of the population. Typical broad methods of
advertisement by popular media of billboards, magazines and newspapers would then be most
appropriate, with special emphasis on reaching out to college-aged students looking to purchase their
first mini-fridges (the beginning of the proposed life cycle of our modular refrigerators).
Scaling to Mass Production
Manufacturing Process
The standard manufacturing process for refrigeration is detailed below:22
1.
The exterior of the machine is made from coiled sheets of steel and the interiors are made
from rust-resistant aluminum lined with an acrylic shell
2. A shearing machine slices steel into pieces for the top, back, and sides
3. Each piece goes to a punch press to create holes for wiring
4. Break press forces the steel against a forming dye to form edges
5. Workers place the pieces of the refrigerator for the outer shell into an assembly apparatus
which holds them together
6. The interior is formed via a vacuum forming machine which heats a sheet of plastic and
shapes it against an aluminum mold
7. The excess plastic is carved off of the interior pieces
8. The freezer and fridge sides are slid into place
9. Copper tubes are laid along the outer edge which circulate gas to prevent moisture buildup
10. A precut face frame is placed into position
11. Foam is injected between the interior and exterior walls which insulates and gives the
refrigerator structural rigidity
22
Science Channel; http://www.youtube.com/watch?v=YE-TqX-FBeI
a. Blowing agents are inserted from the "doghouse" (bottom back part of the fridge), and
the foam is blown upward such that it splatters at the top of the fridge and grows
downwards.
b. Insulation is overpacked to 12% above baseline to avoid air pockets
c. Doors are insulated by using a nozzle spray similar to the shell method, or by spraying
onto the outer door and laying the inner door on top of it
12. The internal circuitry is installed including:
a. An evaporator
b. Electrical control panel connected to a microprocessor
c. Compressors
d. Radiator
13. Finally, the refrigerator doors are added
The goal of our refrigerator design is to maintain as much of this manufacturing process as
possible which will allow us to decrease initial manufacturing costs. While the internal circuitry and its
installation are going to remain largely the same in the manufacturing of our new product, the main
difference will be in the addition of the insulation. While current insulation in refrigerators are injected inbetween the walls, our cellulose sponge insulation needs to come in pre-cut sheets to maintain its
stability. In addition, we need to address the issue that plagues all insulation which is moisture which
can lead to mold and decreased effectiveness. Therefore, to accommodate these two requirements, we
will vacuum seal the insulation into the sides of the walls using a Mylar bag which adds a layer of
protection against moisture and creates a singular component that eliminates the need to insert
insulation after the refrigerator has already been assembled. In addition, vacuum sealing the insulation
will allow for a tight fit which negates the benefit of injecting the insulation to ensure total and complete
coverage of insulation.
The rest of the manufacturing process is common practice for the refrigeration industry so the
only excess costs incurred will be the costs for new casts for the individual parts. The rest of the
process has been proven for decades and we can qualitatively say that after these initial investments,
the product will be able to be effectively mass produced on a global scale. In addition, the dimensions
of our current refrigerator (´ ZLGH ´ GHHS DQG ´ WDOO) are similar to the dimensions of currently
manufactured mini-fridges which will allow us to use similar casts and electronic components.
Market Analysis
US Sales and Revenue
An initial examination of the overall consumer refrigeration market shows a saturated, slow
growth industry, however there still exists a great potential for revenue. As mentioned earlier, nearly
every household in the United States has a refrigerator, with 17% of households having two or more
refrigerators.2 According to the 2010 Census, there are 130 million housing units in the United States,
which represents an installed base of at least 150 million refrigerating units in operation. Approximately
12 million refrigerators were sold in the US in 2010. It is conservatively estimated that growth will
remain steady at the pre-recession 3% yearly growth, which accounts for natural population growth as
well as replacement of existing units.23 Our goal is 5% US market penetration in year 2020, which
would mean about 800,000 sales. At an estimated cost of $300 per stackable unit, this would result in
about $240 million / yr in revenue in 2020.
World Sales and Revenue
While the more affluent US market represents an initial marketing focus for the introduction of
our product and ramping up mass production, the real potential for revenue and profit margins exist in
our international sales. As discussed earlier, there are several issues in overseas countries that need to
be addressed, including inconsistent and unreliable access to electricity and the impoverished regions
of the country which lack an affordable refrigerating solution. The main growth in the expansion of the
global middle class has been in Asia, as demonstrated in Figure 2 below highlighting the explosion in
both the size and expenditures of the middle class:
Figure 2: Change in Size of Middle Class by Region24
This represents a new untapped market for future growth opportunities. Worldwide there were
about 90 million refrigeration units sold in 2010, with Asia (excluding Japan) accounting for more than a
third of those sales (approximately 31.5 million sales). Worldwide the growth is an average of 3%
annually, with higher growth of nearly 5% concentrated in the high economic growth developing Asian
countries including China, India, and Vietnam.25
With that being said, we believe the best use of resources would be to focus on this expanding
Asian market in conjunction with the introduction into the US market. With 5% annual growth as
23
Jarn; http://www.ejarn.jp/Type_news_inside.asp?id=11271&classid=4
Asian Development Bank; http://www.adb.org/Documents/Books/Key_Indicators/2010/pdf/Special-Chapter02.pdf
25
Jarn; http://www.ejarn.jp/Type_news_inside.asp?id=11271&classid=4
24
previously mentioned, in 2020 there will be approximately 51 million refrigerators sold per year. If we
assume a 10% market penetration in year 2020 for this relatively fast growth market, this would equate
to about 5 million sales per year. At an estimated $300 per stackable unit, this would result in about
$1.5 billion / yr in revenue in 2020.
Additional revenue could be gained from marketing the product to low-growth European
countries, however at this time it would be much harder to gain significant market penetration into this
saturated and stable market, so we believe the bulk of our international expansion should be focused
on the opportunity for high revenue and market penetration that exists with the rapidly expanding Asian
middle class.
Profitability
Due to the minimal changes in manufacturing processes and the huge potential for growth both
domestically and internationally, this product can overcome the initial investment costs for further
research and development as well as one-time manufacturing upgrade equipment costs by rapidly
moving to mass production. Most of the components, materials, and required labor will be the same
resulting in no significant deviation from current industry standard prices. The main increase in cost will
be due to the change in insulation. $VVXPLQJD´WKLFNQHVVRILQVXODWLRQZKLFKLVVWDQGDUGRQPRVW
small refrigerators, this would result in approximately 3 ft3 of insulation. The R value of expanded
polystyrene foam was found to be 5.0 m2*K/W*in whereas the R value of cellulose insulation is about
3.7 m2*K/W*in. While we could not locate the R value for cellulose sponge after an exhaustive technical
literature and internet search, we assume that the R value would be higher since we are introducing air
into the component which is a very strong insulator. Therefore, when comparing insulation we will use
3.7 as our very conservative estimate, keeping in mind that costs may be lower than we expect. Using
this 3.7 value, we would need approximately 35% more insulation to achieve the same thermal
properties, requiring 4 ft3 of cellulose sponge. Therefore, the original expanded polystyrene would cost
$42.78 / ft3 compared to the cellulose sponge cost of $46.89 / ft3, meaning an increase of 3% over a
standard refrigerator priced at $300. In a 2008 survey sponsored by DuPont and Mohawk Industries,
respondents replied that they would be willing on average 8.3% more for a product that uses renewable
resources.26 This means any increase in price over baseline for the insulation would be tolerated as it
falls within this value.
Since most companies group refrigeration devices in with other home appliances when they
report their finances to the SEC, the location of a profit margin figure was difficult. In other instances,
there is no clear separation on the financial documents between consumer and commercial
refrigeration revenue and profits. Therefore, we asked Scott Shaver, manufacturing manager from
General Electric, directly regarding the financial side of the business, in respect to just the consumer
refrigeration market. He replied that the average price of a refrigerator is between $700 and low $800's
and that the typical profit margin on just the fridge component is about 15%. Therefore, this confirms
our original assertion that this is a very profitable approach regardless of any increased costs that are
not passed onto the consumer for sake of competitiveness in the market.
26
HGTV; http://www.hgtvpro.com/hpro/nws_industry_news/article/0,2624,HPRO_26519_5847752,00.html
Prospects for Future Innovation
In our initial research, it was apparent that many components of the refrigerator have room for
innovation and progress. However, most of these considerations were out of the scope of our project.
One electrical component that was considered was the compression cooling unit. In the past decade,
Freon (CFC) has been phased out and replaced with hydrochlorofluorocarbons (HCFCs) and ultimately
hydrofluorocarbons (HFCs) which are less damaging to the environment. New technology has been
devised and tested by Cool Chips plc in which there is no need for any refrigerant. The device is
essentially a silicon chip where a low level of current is run through the chip to cool the surrounding
air27. The potential of this chip has already been demonstrated in commercial refrigeration. Since this is
a new technology that has only been developed in the last five years, it is not yet prevalent in the
market. It is our belief that this technology, if incorporated into our current design, would be an
additional improvement to making our product more "green." This technology is projected to cost only
$5-15 when mass production has been reached because the metal used in the product does not have
to be pure, driving down the cost considerably. Most refrigerator cooling units operate at 45% Carnot
efficiency. However, this new cooling chip is greatly improved, operating at 55% Carnot efficiency28.
While this is still in the patent phase, there has been a strong interest in the potential of this technology
as it would be greener, smaller, and more efficient when compared to current solutions.
Conclusion
There is a large demand among the American population for increased energy efficiency
accompanied by the advancements in technology. Refrigerators are an essential component of the
American lifestyle, from the mini-IULGJHLQWKHFROOHJHVWXGHQW¶VGRUPURRPWRWKHIXOO-scale refrigerators
that come along with moving out and starting a family. By focusing on two key aspects of the heavily
developed refrigerator, insulation and its overall design, we were able to take a large step toward our
ultimate goal of developing the next iteration of green refrigeration. While the design and engineering
are important aspects of a product, it is the market research and plan that help move ideas out into
society. The strength of our product lies in its versatility because it is able to cross borders. It is not like
DQ ³$PHULFDQ FDU´ WKDW LV WRR ZLGH IRU WKH QDUURZ URDGZD\V RI ,WDO\ ,W LV E\ GHVLJQ PRGXODU DQG
customizable, giving it the capacity to be sold in places such as Europe and Asia, where the latter has a
large growing market for refrigerators due to its growing middle class and expanding infrastructure.
With further developments to the product, greater environmental and economic benefits could
assuredly be yielded both domestically and internationally, but as any movement toward the
preservation of the environment, each iteration is a step forward in the right direction.
27
28
Cool Chips Inc; http://www.coolchips.gi/technology/index.shtml
Kanellos. Michael; http://news.cnet.com/2100-1008_3-5194349.html?tag=nefd.top
Acknowledgments
·
·
·
·
·
·
·
·
Dr. Malcolm Cooke, Case Western Reserve University
Dr. David Schiraldi, Case Western Reserve University
Dr. Marsha Bischel29, Armstrong Materials Scientist
Dr. Amy Campbell30, Armstrong Materials Scientist
Scott Shaver31, GE Appliances Engineering Manager
Saint-Gobain Representatives and Sponsors
Adrian Slattery, CIA
Matt Beckwith, CIA
Additional Resources
http://www.adb.org/Documents/Books/Key_Indicators/2010/pdf/Special-Chapter-02.pdf
http://buildingsdatabook.eren.doe.gov/TableView.aspx?table=5.1.3
http://www.energysavers.gov/your_home/designing_remodeling/index.cfm/mytopic=10170
http://www.energysavers.gov/your_home/insulation_airsealing/index.cfm/mytopic=11660
http://www.healthyhouseinstitute.com/a_681-Fiberglass_Insulation_Use_With_Care
http://www.polyurethane.org/s_api/sec.asp?CID=903&DID=3616
http://www.madehow.com/Volume-5/Sponge.html
http://news.cnet.com/2100-1008_3-5194349.html?tag=nefd.top
29
Bischel, Marsha. Personal Interview. 25 February 2011.
Campbell, Amy. Personal Interview. 25 February 2011.
31
Shaver, Scott. Personal Interview. 25 February 2011.
30