1. Department of Mechanical and Energy Engineering
University of North Texas, Denton, TX
MEEN 4250
A SENIOR DESIGN PROJECT
PREPARED IN PARTIAL FULFILLMENT OF
THE REQUIREMENT FOR
THE DEGREE OF
BACHELOR OF SCIENCE
IN
MECHANICAL AND ENERGY ENGINEERING
Isolated Air Conditioning System
Submitted by:
Taylor Bontz
Josiah Bujanda
Chris Hubbard
Adam Mengestab
Edgar Vazquez
May 7, 2015
FACULTY ADVISOR
_________________________
Dr. Yong Tao
This report is written in partial fulfillment of the requirements in MEEN 4250. The contents
represent the opinion of the authors and not the Department of Mechanical and Energy
Engineering

2. 1
Team Signature Page
This report was prepared by the following team members:
___________________May 7, 2015
Taylor Bontz
___________________May 7, 2015
Josiah Bujanda
___________________May 7, 2015
Christopher Hubbard
___________________May 7, 2015
Adam Mengestab
___________________May 7, 2015
Edgar Vazquez

3. 2
Table of Contents
Team Signature Page .................................................................................................................. 1
Table of Contents......................................................................................................................... 2
List of Figures............................................................................................................................... 3
List of Tables ............................................................................................................................... 4
Ethical Design Statement:............................................................................................................ 5
Environmental Impact Statement:................................................................................................ 5
Background…………………………………………………………………………………………........6
Problem Statement…………………………………………………………………………………....…7
Goal Statement…………………………………………………………………………………………. 7
Objectives……………………………………………………………………………….……..... ……....7
Form and Functionality…………………………………………………………………………7
Constraints………………………………………………………………………………………8
Intended Clients…………………………………………………………………………….….. 8
Literature Review……………………………………………………………….....………………..…...9
Benchmarking……………………………………………………………………………………...…... 10
Design Specifications…………………………………………………………………………..……... 11
Function Means……………………………………………………………………………..…………. 12
Design Summary………………………………………………………………………..…………….. 16
Initial Design…………………………………….……………………………………………...16
Final Design…………………………………………………………………………….……....16
Mechanical Design……………………………………………………………….…...17
HVAC Design…………………………………………………………………………..19
Controls Design………………………………………………………………….…… 21
Bill of Materials………………………………………………………………………………………….25
Project Planning……………………………………………………………………………………..… 26
Gantt Chart………………………………………………………………………………….… 26
Failure Modes and Effects Analysis………………………………………………………….27
Engineering Analysis…………………………………………………………………………….……. 28
Minimized Volume Analysis…………………………………………………………………..24
Thermal Comfort……………………………………………………………………………….25
Heating Ventilation and Cooling…………………………………………..…………………..26
Testing and Results……………………………………………………………………………….……27
Testing Procedure………………………………………………………………………..……30
Results…………………………………………………………………………………….…… 31
Conclusion and Opportunities for Improvement……………………..…………………………..….32
References……………………………………………………………………………………………...33

4. 3
List of Figures
Figure 1: Chillipad Mattress……………………….…………………………………………………...10
Figure 2: Japanese Capsule Hotel……………………………….………………..………………….10
Figure 3: Guide Rail View 1………………………………………………………………………..……7
Figure 4: Guide Rail View 2……..………………………………………………………………….….11
Figure 5: Initial Design CAD……………………………………………………………………...……12
Figure 6: Final Design CAD……………………………………………………………………………17
Figure 7: The Skeleton (Left), Struts (Middle), and Neodymium Magnets (Right)…..….………17
Figure 8: Required Safety Netting…..…………………………………………………………………17
Figure 9: Thermal Comfort Tool….….……………………………………………………...…………19
Figure 10: AC Unit….…………………………………………………………………………………...20
Figure 11: Air Vent…..……………………………………………………………………………….…20
Figure 12: Temperature and Humidity Data….………………………………………………………21
Figure 13: Raspberry Pi Home Weather Chart……….……………………………….…………….23
Figure 14: Mechanical Relay...….……………………………………………………………..…...…24
Figure 15: Portable Interface….………………………………………………………..……………...23
Figure 16: Control System Display…..………………………………………..………………………22
Figure 17: Gantt Chart………………...….…………………………………………………………….28
Figure 18: Air Flow Diagram………..…………………………………………….……………………32

5. 4
List of Tables
Table 1: Customer Design Specifications..……………………………………………………….….12
Table 2: Function Means……………………………………………………………….…….……..….13
Table 3: Bill of Materials …………………………………………………….….……….……………..26
Table 4: FMEA………………………………………………………………...….……………………..28

6. 5
Ethical Design Statement
In accordance with the National Society of Professional Engineer’s Code of Ethics, as
reviewed in full by each team member, all designs and processes take into consideration the
safety of the public with highest regard.
Environmental Impact Statement
In the design presented, all materials selected have been assessed for their
environmental impact and any materials or combination therein deemed hazardous or toxic
have been eliminated.

7. 6
Background
The Isolated Air Conditioning System (IACS) team’s goal was to design, test and build a
prototype cooling system specifically designed for the Peterbilt sleeper cabs. The concept was
to create a system that not only cooled the operator faster than it would take to typically coo him
or her in an entire truck cab, but to also drastically reduce the energy usage via an interactive
monitoring system. It is to consist of a series of hollow aluminum rods as a skeleton base, along
with a thick polyethylene cell foam insulated tarp to trap the cold air inside. The sleeper system
was also intended to have an air conditioning system located underneath the bed that would
feed the air through a vent system directly into the canopy area. The system will also
incorporate a series of high powered, neodymium magnets in order to alleviate the opening and
closing process. Also, a series of pneumatic struts will be put in place to relieve the tension on
the skeletal structure while simultaneously assisting the user to open and close the canopy
system with ease. The entire cooling system is to be operated and controlled via a raspberry pi
microcomputer with micro controller inputs and output controller relays via a low voltage output.
This system is put in place to not only allow monitoring of comfort levels inside of the canopy
system, but also creates a user interface in which the operator is able to interact with the
functionality of IACS. This is in order to create not only a comfortable sleeping space, but a
comfortable living space as well. The design team hopes that IACS will help improve the
sleeping comfort levels of truck drivers throughout the country while also drastically reducing the
overall energy usage as well. Building automation is the automatic and centralized control of a
building’s heating, ventilation, air conditioning, lighting and other systems. Automation can
provide functionality, flexibility, real time monitoring, and data analysis. When building
automation is used to control mechanical building functions the system can improve comfort
levels while reducing energy loads. The reduction of energy and the intelligent control of
building functions forms two of the project objectives. The project is intended to develop a cost
effective method of providing optimized thermal comfort. The developed system should be
capable of creating a database of information, which will be used for processing, analyzing, and
improving system functions. In addition to developing an effective management system, the
system shall be capable of achieving a high level of compatibility with existing infrastructure,
such as, wireless connectivity, user developed applications, and other future technological
developments. Control systems take specified values and use them to change the physical
quantities of more complex systems. Typically a control system uses sensors to gather data, a
method of comparing incoming data with the existing state of the controlled system, and a
controller to pass signals that can be varied, in order to influence the system to perform the
desired output. The control system, that is used to manage temperature, humidity, data
collection and analysis, scheduling, and power switching, is based off of open source
technologies and user generated content, this provides a high level flexibility and adaptation

8. 7
Problem Statement
Goal Statement
The IACS team’s goal was to create an enclosed canopy system inside of a standard
Peterbilt sleeper cab that would alleviate some of the energy usage on the truck’s air
conditioning system by reducing the overall area that the system needs to cool. The goal is to
create a balance by increasing the time it takes to cool the operator while also reducing the
amount of energy used, but in a system that still keeps the driver comfortable in both space
used as well as rapidity of air cooling inside the system.
Objectives
The team’s primary objective for the project was to create a truck mattress canopy that
would do the following:
- Create an effective, nearly air-tight seal around the user using a polyethylene
insolated canopy in order to reduce the amount of area that would have to be
cooled while the truck driver sleeps.
- Utilize a portable cooling system to bring cool air into the attached canopy once
the seal is made.
- Implement an interactive user integrated system to automatically adjust cooling
temperatures while also maintaining energy efficiency to reduce waste.
- Minimize the weight of the material used
- Ensure that the interactive system does not utilize more energy than would
otherwise be saved through the interactive canopy system.
Form and Functionality
The basic design of the IACS will consist of a series of three lightweight aluminum rods
spread out evenly across the top of the mattress that the operator sleeps over. The “skeleton”
will be mounted onto the wall via a system of hinges in order to allow the canopy system to be
lifted out of the way so the operator can still perform the typical tasks necessary without
interference. A second set will be attached to another series of lightweight aluminum rods,
giving each series an “L” shape, but allowing them to bend inward to ensure they remain as low-
profile as possible. A thick, foam insolated canopy tarp will be attached to the top of the three
rails, utilized specifically to entrap all cool air while preventing the outside hot air from entering
the system. Three more rods are attached along the sides of the L shaped aluminum skeleton,
going from head to foot of the bed area. These are for the specific purpose of allowing the tarp
to remain upright and allow for the maximum amount of sleeping space to provide a comfortable
living/sleeping area.
To ensure that this product utilizes as little energy is possible, a small cooling system will
be installed underneath the bed in order to prevent turning on the entire truck’s electrical system
to cool the enclosed space. There will also be a duct system specifically built to transmit the
cool air directly from the air conditioning system to an in feed attached to one end of the canopy.
Also, in order to make this a more manageable and customizable experience for the customer,
an interactive user interface will be installed underneath the enclosure, just below the mattress

9. 8
strut box spring area in order for the user to adjust the system while still inside the enclosure.
The system will also monitor heat and cooling patterns, and will be attached to several other
potential systems inside the enclosure to make the experience inside the canopy as pleasant as
possible.
Constraints
In order for the Truck Mattress Cooling Canopy to be a success it must first and
foremost fit appropriately inside the dimensions of a standard Peterbilt truck’s mattress area.
The cabs in which the operator will be confined to will have to be the same space in which our
system operates, so space is a primary focus. The system must also be built so that it is easy
enough for one user to operate on their own without any additional support or guidance. This
means it must be easy to lift open, locked into the “closed”, out of the way position without
assistance, as well as have a user interface with the operating system that is easy enough for
anyone to operate.
The system must also properly cool the isolated area to a comfortable temperature in a
significantly shorter amount of time than would typically be required to cool an entire cab. The
structure of the system is also paramount to the project’s overall success. The skeletal structure
holding up the canopy must be large enough to ensure a comfortable sleeping space for the
user. The operating system must also potentially save enough energy to justify its energy usage
in the process. Overall, the project must ensure that the cooling canopy system utilizes as little
energy as possible, while still maintaining the desired comfortable sleeping environment for the
user.
Intended Clients
The Truck Mattress Cooling canopy is being developed specifically for Peterbilt Trucks,
a division of PACCAR, to be used by their customer base. Future possible clients might include
other PACCAR manufacturing companies, including Kenworth and DAF.

10. 9
Literature Review
The primary concepts that the IACS needed to focus on was fluids and thermodynamics.
It was important for us to first analyze what temperature would be necessary for a user to
achieve the ideal level of comfort inside the canopy system. In order to do that, we needed to
attain the ideal comfort temperature levels from the ASHRAE standard 55 [14]. The standard
also focuses on the importance of rising and lowering humidity as well as air speed to balance
with the consumer’s metabolic rates. In order to measure and understand the air speed
balances in the canopy system, we also had to use the fluids concept of dispersion [16].
Once the ideal temperatures and air speeds were obtained, the next step will be an
energy usage analysis. The basic calculations begin by calculating the amount of energy
required to cool the air in the canopy system using the Heat Equation [12]. Once the amount of
energy required is calculated, the sum of the loads will then be multiplied by the time to replace
the total energy used in the system, which calculates instantaneous temperature through heat
transfer.
To calculate the heating load coming from ambient air through the insulated tarp a heat
rate must be calculated. This heat rate is calculated by using the Equivalent Resistance Method
[2] which uses the properties and parameters determined from the ASHRAE standard 55.
The control system is designed by determining the system parameters that were
deemed necessary in order to control the thermal comfort levels of the space. Statistical data
shows that operating cost can be significantly reduced through occupancy control, ventilation
control, temperature and humidity measurement, or return air or CO2 level controls [5]. The
ability to monitor various aspects of system parameters are essential in determining the efficacy
of an automated system. The measurement of energy consumption and performance is key in
understanding the impact an automated management system will have when in use. BAS’s
require measurements at key points in the building system to monitor part-load operation and
adjust system set points to match system capacity to load demands. [1] Due to the majority of a
building’s consumption being accounted for by the HVAC system, it is apparent that large
amounts of energy use can be reduced by developing a system which meets the following
requirement set by the U.S. General Services Administration, The system shall consist of series
of direct digital controllers interconnected by a local area network. BAS system shall be
accessible through a web browser. System shall have a graphical user interface and must offer
trending, scheduling, downloading memory to field devices, real-time “live” graphic programs,
parameter changes of properties, set point adjustments, alarm/event information, confirmation
of operators, and execution of global commands. [1]

11. 10
Benchmarking
We are in a sort of unique market with our product, as there doesn’t seem to be a lot of
competitive designs to compare to the IACS project. However, there are several versions of
processes attempting to just cool the area in which a person sleeps; whether it’s cooling the
mattress material or the sheets they are sleeping on. In fact, the original project was initially
going to be similar to a product called the ChilliPad mattress. This was a thin, soft gel pad that
was placed over a typical mattress that had the ability to both heat and cool the top layer of a
mattress. The initial intention was to create a system similar to this, wherein the initial project
was to design a mattress that could cool itself. However, Peterbilt told the group that such an
item is already available for the sleeper cabs, so the group went with the isolated cooling
system.
This system was strongly influenced by the very popular concept of a portable, efficient
sleeping area that focused on limiting space and energy usage while remaining comfortable for
the customer. These designs are called “capsule hotels”, and are very popular in countries like
Japan and Singapore. The IACS system actually was heavily inspired by this concept, even
utilizing the exact same dimensions of living space to transfer over to the canopy skeleton. Both
systems are designed for comfort and space efficiency in mind, and as such, both systems are
designed to be a standard 4’1”x3’3”x7’.
Figure 1: Chillipad Mattress Figure 2: Japanese Capsule Hotel

12. 11
Design Specifications
Table 1: Customer Design Specifications
Engineering
Characteristics
Rank Units
Specifications
Marginal Value Ideal Value
Canopy temperature 1 °C 27 25
Desired A/C Temperature 2 °C 17 17
Dimensions/Sizing 2 m3
2 2
Heat Build Up 4 kW/h 5 0
Power Usage 5 kW/h 55 30
Air Velocity 6 m/s 0.1 0.1
Based on this table the most important characteristic is the canopy temperature because
the goal of the design is to adjust the air temperature within the canopy to a comfortable level.
The ranks of the characteristics, however, are not that significant in that other specifications are
important to make the canopy temperature possible. For example, air velocity affects canopy
temperature by moving the cold air into the canopy space.

13. 12
Function Means
Table 2 illustrates the means used to carry out each sub-function.
Table 2: Function Means
The following is the logic used to reduce the brainstorming function means table to a more
refined table:
● User input
○ Means removed: Thermostat, touch screen, voice activate, phone app, switches
○ Reason for removal: A touch screen is expensive and can lead to complications if
an attempt is made to integrate it into our design. The same was logic was used
to eliminate voice activated and phone app means. The thermostat and switches
would give the user a limited use of the system
● Cooling
○ Means removed: ice, heat exchanger, compressor
○ Reason for Removal: Low efficiencies
● Heat management
○ Means removed: Heat exchanger, nothing
○ Reason for Removal: There is no use for heat in our design and must be
removed efficiently. Venting the heated air is the simplest means.
● Power
○ Means removed: nuclear, alternator, solar, truck battery, rechargeable batteries,
auxiliary batteries
○ Reason for Removal: weight issues and complexity ruled these means out.
● Air Delivery

14. 13
○ Means removed: through mattress, through wall
○ Reason for Removal: user comfort eliminated air delivery though the mattress.
Air delivery through the wall would interfere with existing Peterbilt design
● Air Circulation
○ Means removed: natural, positive pressure
○ Reason for Removal: there are more efficient means to circulate air
● Support
○ Means removed: wood, retractable truss, solid piece
○ Reason for Removal: weight issues and fragility eliminated these means
● Air Seal
○ Means removed: snap buttons, Velcro, magnets, counterweights
○ Reason for Removal: there are more effective sealing means
● Canopy
○ Means removed: metal, leather, wood, hard plastic,
○ Reason for Removal: weight issues eliminated these means
● Power regulation
○ Means removed: recharging system
○ Reason for Removal: recharging the system complicates the system and does
not contribute greatly to the main function of the design
● Monitor comfort
○ Means removed: Psychrometer, infrared radiation
○ Reason for Removal: complexity and ease of integration to the monitoring
system eliminated these means
● Select Mode
○ Means removed: dial, fuzzy logic, computation AI model, equation based, table
based, fixed
○ Reason for Removal: The path chosen to fulfill this sub-function is the easiest to
learn.
● Control Mode
○ Means removed: microprocessor software, signal processor, programmable logic
controller, application specific integrated circuit, analogue, digital, cams and
gears
○ Reason for Removal: the current mean is cheaper and easier to access.
Effectiveness of the current means can be expanded beyond the other means.

15. 14
Design Summary
Initial Design
The first design process that was going to be used for the canopy system relied on the
skeleton structure being held in place by a rail system. This system would be pushed and pulled
open and closed back into place through two guide rails on a track. The concerns we had with
the guide rail system were that it would be difficult to line up two separate thin rails to a relatively
heavy skeleton and tarp structure. Also, the sliding rail system would interfere with the
functionality of the safety harness that is required to be inside every Peterbilt sleeper cab, so it
wouldn’t work because of that.
Figure 3: Guide Rail View 1
Figure 4: Guide Rail View 2

16. 15
It also included a canopy system that had two separate tarps on the same semicircular
skeleton. Some of the flaws with this design included the significant drop in overall living space
when compared to the “L” shaped skeleton, the difficulty with keeping two tarps consistently
spaced enough to allow cool air to flow into the system, how to create a porous tarp, and how to
create a strong, curved skeleton structure. As such, we decided to change our design during the
second semester of the project to improve the AICS.
Figure 5: Initial Design CAD

17. 16
Final Design
Mechanical Design
For the final design, the primary objective was to make the structure had to be
lightweight but strong, so the canopy skeleton was held in place using hollow 6061 aluminum
square rods. With a weight of about 1 lb. per square foot, and a yield strength of 55 Mpa as well
as the inexpensive cost, it was the most logical choice as far as skeleton material. As previously
mentioned, the “L” shaped skeleton was inspired by the Capsule hotel dimensions, which lead
to the lengths of the rods being cut into 4’1 wide and 3’3” long.
In order for the tarp to lift and lower as well as retract out of the way of the user,
inspirations were derived from both tanning bed doors as well as the pivot point systems of flat
screen TV mounts. To achieve this goal, a system of hinges were placed connecting the
aluminum rods to the wall in the horizontal position, and each rod to each other as well in the
vertical position. With the former set of hinges, the entire structure was able to lift itself up (with
the assistance of two 24-pound struts) to allow the user to get out of the structure. The two
struts were calculated to achieve a comfortable amount of assistance to lift the 32 pound
canopy, but also leaving little resistance to make closing the structure easy for the user as well,
with only 8 pounds of resistance.
In order for the structure to maintain its “L” shape while the first set of hinges lifts the
structure, a series of neodymium magnets are put on each end with brackets adjacent that
“snap” the structure into its “L” shape form, which also make it easier to open and close the
canopy without issue. Once the magnet connect is broken, the second set of hinges then allows
the vertical bars to fold back in on themselves, which helps minimize the total amount of space
that the AICS takes up while in the closed position.
A ½” thick, insulated tarp was used to function as the outer canopy built specifically to
entrap the cool air being fed in through the AC system, as well as prevent warm air from
entering the AICS. The tarp was made of a ½” cell foam insolation covered by a 12mm thick
polyethelene woven tarp fabric, which functioned as a relatively light weight cover with good
heat containing properties. In total, the combination of the skeleton and the canopy weighed in
at just around 32 pounds, which met the group’s goal of making the cooling system effective
while also maintaining a light weight. Also, an addition to the canopy was the integration of
Velcro to attach the tarp to the skeletal structure. This not only gives the added option of
removing the tarp for even more reduction in occupied space while in the “closed” position, but it
also allows the employees to use the required safety harnesses that come standard in every
Peterbilt sleeper without any interference.

18. 17
Figure 6: Final Design CAD
Figure 7: The Skeleton (Left), Struts (Middle), and Neodymium Magnets (Right)
Figure 8: Required Safety Netting in an Actual Sleeper(Left), Velcro system (Right)

19. 18

20. 19
HVAC Design
Thermal comfort is a particularly important aspect of this design. The user should feel
comfortable at all times enclosed within the cocoon. Berkeley offers a tool that models thermal
comfort, using AHRAE-55 as the standard. Variables that this tool takes into account are air
temperature, mean radiant temperature, air speed, humidity, metabolic rate, and clothing
insulation. By adjusting these values to our design specification we can ensure a comfortable
environment for our user. The following image illustrates our design values.
Figure 9: Thermal Comfort Tool
Due to limitations in cost and fabrication, the design of the HVAC system is very simple.
The cooling load is supplied by a window air conditioning unit that has a cooling capacity of
3516 W. The load that this system actually supplies is 500 W. This load works as a good
simulation for a Peterbilt compressor which supplies a 700 W cooling load – a small difference.
The cool air goes through ducting with a diameter of 6 inches and enters through the
cabin wall at and airspeed of 4.5m/s. This airspeed is considerably faster than the ideal 0.1m/s.
This system addresses this problem by having the air enter the sleeping space through a vent
that has upward facing blades. The blades direct the air towards the tarp ceiling, causing
dispersion and allowing for a more comfortable environment.

21. 20
Figure 10: The air conditioning unit is supplying air to the system through simple ducting.
Figure 11: Air enters the sleeping space at an upward angle determined by the vent blades.

22. 21
Controls Design
A summary of the control system is as follows, the control system uses a micro
processing controller to manage the input and output signals of the system. A web server is
used to generate the user interface, as well as provide connectivity for many devices. Data is
collected and analyzed in real time by temperature and humidity sensors, which is then used to
generate and display graphical representations. The microcontroller is also used to control a
custom built relay panel which can switch 6 225V circuits at 10Amps. The relay panel is used to
provide the user with an intuitive energy management system that is capable of learning user
habits and providing direct control over any device connected to the relay.
The control system is specified as follows:
Device Description Function
Raspberry
Pi
A micro computer and controller
with various I/O capabilities.
Controls the power relays with a 5V
coil activation signal
Mechanical
Relays
8 Channel 10A 250VAC relays
Custom
Webserver
A Javascript NodeJS based
webserver that is secure,
versatile, and modifiable
Handles data requests used for
scheduling, monitoring, and future
additions
Intuitive
user
interface
A TFT Touchscreen is used for
display, the Python scripting
language performs
Gathers user input through
touchscreen and webserver
The I/O from the user, providing
visual feedback as confirmation
of system functionality
AM2303
TH Sensor
A temperature and humidity
sensor with a sample rate of 2
seconds
Performs raw data collection
A central processing unit is a device that is used to perform calculations and carries out
the logical instructions necessary to perform various tasks through the input and output. The
Raspberry Pi is used as the central database and control hub for the system. An Adafruit DHT
library is used to communicate with the sensor and all data collection from the AM2303 sensor
is passed to the raspberry pi and compiled by a MySQL database.

23. 22
Figure 12: Shows preliminary temperature and humidity data. The comma separated value
database is then sent to an HTML page with NVD3 charts for d3.js is used together with a
node.js Javascript file that contains a node.js Express web server. The web server uses the
data to construct a graphical representation of the temperature and humidity data that is easy to
read and understand. The web server also handles the functions necessary for scheduling and
future additions. The remote functionality of our system ensures that our design is quick and
easy to deploy in the field, while remaining cost effective, and can interface with future
developments. Although the initial specifications of the design called for a TFT touchscreen
interface which would provide an intuitive user interface, it was determined, that the screen was
ineffective in providing an easy to use interface. In order to remedy this issue, the web server
was designed to accommodate any touchscreen device that is capable of using an HTML page.

24. 23
Figure 13: Shows the chart developed with the web server
This change provides our system with unlimited connectivity as any device that is
capable of running Javascript can be a host device. This means that most smart phones,
tablets, and laptops can be used with our control system without any additional software being
required. The web server is designed to work on a local area connection that can be broadcast
via wifi but that does not require connection to the internet. If so desired the web server can be
connected to the internet which will allow the system to be remotely accessible from anywhere
in the world, field adjustable, and will allow for further user customization. As designed the
system can be accessed and monitored from any location. Another benefit of the designed
system is that the software is constantly updating, this means that issues that are found in the
field, or software bugs, can be remedied quickly. In order to remain economically viable the
control system was specified to have extremely low power consumption, upon testing the
control system power consumption, a peak power of 22 watts was measured. The control
system is based off of an open source software known as Python. Python allows us to use the
data that is collected from a temperature and humidity sensor and import it into a myriad of user
defined functions. For our system we collect the raw sensor data and plot a real time graph the
shows the change in humidity and temperature over time. This data collection serves as the
building block for the intelligent management system. A predetermined schedule can be set,
which the system will adhere to using each new data entry. Essentially this functions like an
intelligent thermostat, but what sets our system apart from other products on the market is the
ability to control devices remotely, the ability to learn user patterns and preferences to adjust
comfort levels, regulate temperature, and humidity, connect with user developed applications on
the Apple Store and Google Play, interface with future technology.

25. 24
Figure 14: Mechanical Relay
In order to control separate power circuits, a custom built mechanical relay is used to
individually switch up to six circuits. The relay bay is connected to a Raspberry Pi output signal
which can be controlled by the web server. This design provides the user with the ability to
access the HTML web page with a device of their choosing and manipulate any device that is
plugged into the power relays.
Figure 15: Shows the simple intuitive interface

26. 25
This can include but is not limited to AC units, TVs, radios, and computers. The system
then monitors power consumption and creates a log to be used for determining system
performance. Advanced functions can be programmed in order to provide the energy
management system with parameters to further reduce use and cost. An example of this could
be seen if the user has a laptop, night light, and a TV plugged into the relays; the light and the
laptop could be switched off automatically if the user forgets to turn them off or unplug them
while they watch TV. Again, this is just one example out of the many possibilities that exist
because of the high level of adaptability that our system presents.
Figure 16: Control System Display

27. 26
Bill of Materials
Table 3: Bill of Materials
It is important to note that Peterbilt has also provided a mattress, a bed frame, struts to
support the bed frame, and a locking device. These components have a total value of
approximately $500.

28. 27
Project Planning
Gantt Chart
The Gantt chart illustrates the progress that’s been made as well as the future
scheduling of the project.
Figure 17: Gantt Chart
Each member is assigned a task for the following semester. Edgar has been assigned
with modeling air through the holes of the canopy as well as calculating the optimal energy
loads the mini HVAC system will encounter. Adam is tasked with modeling the thermal comfort
of our designs envelope. Edgar and Adam will be working together to design and assemble the
HVAC component of the project. Taylor is in charge of the canopy and skeleton portion of the
design. Chris is tasked with designing and building the guide track. Taylor and Chris will be
working together to assemble the guide track and all its parts. Josiah was chosen to be the
purchaser. Josiah is tasked with designing and assembling the user interface. The group will
work together to complete a mock up of the design as well as completing any final testing
required for the design.

29. 28
Failure Modes and Effects Analysis
To ensure user safety and to predict any potential failures in the design, a Failure Modes
and Effects Analysis was performed on all major components of our current design. Table
5displays the results of the FMEA made for the project.
Table 4: FMEA
The Rail system, cover, and skeleton of the system are designed to ensure that no
leaking is taking place. Using the energy effectively is a high concern. To ensure safety towards
the user, pinch points and other harmful areas within the design are padded or made aware to
the user through warning labels. In the instance that the planned user interface malfunctions,
there is a backup on/off switch that will be implemented within the design.

30. 29
Engineering Analysis
Minimized Volume Analysis
Because the intention of this project was to save energy, it was necessary to calculate
the amount of energy that our design saves. The amount of energy required to change the
temperature (in this case from 100°F or 37°C to 75°F or 23°C) of a given material (in this case
air) of a given volume can be calculated using the equation:
𝑄 = 𝜌𝑉𝑐∆𝑇
Where:
𝑄=energy required
𝜌=density
𝑉=volume
𝑐=specific heat
∆𝑇=change in temperature
When comparing the theoretical amount of energy required to cool a larger volume (the
full cabin) versus a smaller volume (that of the inside of the tarp) of the same material and
temperature difference the only difference will come from the change in volume. So when
considering that the volume of air within the tarp is 2.41m3
and the larger is approximately 5
times larger, the amount of energy required to change the temperature of the full cabin (206kJ)
will be 5 times more than for just the inside of the tarp (41.2kJ). So the tarp causes an 80%
decrease in required energy.
To solve for instantaneous temperature the sum of the loads multiplied by time can
replace Q.
( 𝑞 + 𝑃) 𝑡 = 𝜌𝑉𝑐(𝑇𝑖0 − 𝑇𝑖)
The two loads are the cooling load (P=1758 W) and a heat rate through the tarp, q, which is
calculated by using the equivalent resistance method:
𝑞 =
𝑇∞ − 𝑇𝑖
𝑅 𝑡𝑜𝑡
𝑅 𝑡𝑜𝑡 =
1
ℎ1 𝐴
+
𝐿
𝑘𝐴
+
1
ℎ2 𝐴
Figure 18: Diagram of
EQR method variables

31. 30
In this case:
Ambient temperature outside of the tarp, 𝑇∞ = 37°𝐶
Temperature inside of the tarp, 𝑇𝑖 = 23°𝐶
Initial ambient temperature inside of the tarp (equal to 𝑇∞), 𝑇𝑖0
Equivalent resistance throughout tarp boundaries 𝑅 𝑡𝑜𝑡 = 0.57322
𝐾
𝑊
Surface area of tarp, 𝐴 = 4.606 𝑚2
Convection coefficient outside of tarp,ℎ1 = 10.45
𝑊
𝑚2 𝐾
Convection coefficient inside of tarp, ℎ1 = 8.07
𝑊
𝑚2 𝐾
Tarp thermal conductivity, 𝑘 = 0.0039
𝑊
𝑚𝐾
Cooling air speed, 𝑣 = 4.5
𝑚
𝑠
When the previous equations are put together and variables are rearranged a function of
time to give instantaneous temperature inside the tarp can be made:
𝑇𝑖( 𝑡) =
𝑇∞ 𝑡/𝑅 𝑡𝑜𝑡
𝑡
𝑅 𝑡𝑜𝑡
− 𝑚𝑐
−
𝑃𝑡
𝑡
𝑅 𝑡𝑜𝑡
− 𝑚𝑐
−
𝑚𝑐𝑇𝑖0
𝑡
𝑅 𝑡𝑜𝑡
− 𝑚𝑐
After applying values:
𝑇𝑖( 𝑡) =
49.12𝑡
𝑡
0.57322
− 2966.76
+
1758𝑡
𝑡
0.57322
− 2966.76
−
109770
𝑡
0.57322
− 2966.76

32. 31
Testing and Results
Testing Procedure
According to the U.S. Green Building Council’s LEED requisite for thermal comfort
design, EQ6.1, the intent of designing a system that provides thermal comfort is to promote
occupants’ productivity, comfort, and well-being by providing quality. While the scope of our
project simply does not allow complete adherence to ASHRAE Standard 55-2004 the intent of
our design was based on such standards. By using industry standards, a realistic benchmark
was obtained for testing. The testing performed provided critical insight during the design
process, as well as a greater understanding of how different components of the system could be
improved.
The goal of initial testing was to develop an understanding of thermal comfort and its
properties. Thermal comfort is characterized by the individual’s personal experience. The major
components of thermal comfort that have been defined in ASHRAE’s Standard 55-2004, are the
temperature, thermal radiation, humidity, and air speed. These factors are addressed in
conjunction with a person’s metabolic rate and the insulation of their clothing. In order to
understand the relationships of these factors, it was necessary to first develop an understanding
for the defining characteristics of a thermal environment. In order to achieve this, two different
isolated thermal boundaries were made. We chose wood for the primary boundary material
because of its low cost and the relatively low thermal conductivity of wood, when compared to
other readily available materials such as water, glass, or metals. One chamber was heavily
insulated by a closed cell spray polyurethane foam in order to test for thermal radiation, vapor
leakage, and temperature differential with respect to time. Using a standard window mountable
air conditioner we were able to charge each chamber with cool air and measure the changes
over time.

33. 32
Results
The design is considerably comfortable and surprisingly spacious. The 3 ft. body radius
was enough to satisfy every individual that has been in the sleeping area (approximately 20
people have been inside of the sleeping area.) This was an important comfort parameter to
meet because the challenge was to minimize volume but still keep the design practical.
The upward facing vent blade design fulfils its function to disperse cooling air throughout
the cooled area without abrasively causing forced convection on the occupant’s body. The air
loses a considerable amount of speed when changing direction along the tarp ceiling and also
moves in a slow calm cycle through the sleeping area.
Figure 18: Air flows from the vent towards the tarp ceiling and cycles through the sleeping space
Testing was conducted with an ambient temperature was 23.5°C so the conditions were
not necessarily comparable to the intended use. However, we designed our test to drop the
temperature from 23.5°C to 19°C to simply test the rate of air temperature change
The system was capable of dropping the temperature from 23.5°C to 19°C (74.3°F to 66.2°F) in
13 minutes. This was significantly slower than expected. However this was an advantageous
outcome because of air conditioning comfort rules. The speed allows for a human body to
exchange energy with the surrounding air at a healthy rate.
In addition to cooling the space in good time, the canopy was also capable of retaining
heat extremely well. When the temperature finally made the drop, the system was turned off and
allowed to naturally reach ambient temperature. It took about 18 minutes to reach ambient
temperature.

34. 33
Conclusion and Opportunities for Improvement
This Isolated Air Conditioning System design was successful in creating a low energy
isolated cooling space. It was completed as intended by the use of light efficient materials and a
relatively small power source. An industry implementation of a similar design that uses the same
principles could save a significant amount of energy.
Several changes could be made to this design to improve its efficiency and
effectiveness. The first standout change would be to remove air leakage. Bulb seal could be
utilized to keep cold air from escaping the sleeping space and the space could be kept colder
for a longer period of time. A second change would be to make the skeleton out of molded
plastic to reduce weight. Weight reduction helps to make the design a more seamless
integration with the rest of a truck’s system, and it also becomes less of a hassle to handle for
the occupant.

35. 34
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