2.0 Executive Summary

View Executive Summary as PDF (sections 2.1-2.5) PDF (sections 2.6-2.7)

This Page Contains:

2.1 Product Description (Link to below)

This section is a description of the proposed product, its characteristics and operation that specifically describe the key features and justification as to why they are important and what was done to insure their effective integration into the design.

2.2 Design Relevance (Link to below)

The Design Relevance includes a description of how the product will fit a need and addresses the competition in this area. Evidence for the need of this project is included to justify InnovatioNDistillation's decisions.

2.3 Design Process (Link to below)

The Design Process is a description of the process used and key steps and decision points in the process. Information on how resources were allocated, schedules set, and engineering methods used in the decision making process are included.

2.4 Options Considered (Link to below)

Options Considered provides visually effective sketches, with appropriate features and competing designs. Technical challenges associated with each option are addressed in tabular format.

2.5. Solutions and Rationale (Link to below)

The Soluctions and Rationale is a concise description of the product that was selected for study with key components and features specified. The anticipated strengths and weaknesses of this system are considered.

2.6 Implementation Details (Link to below)

Implementation Details includes a description of the prototype, its operation, and the lessons learned throughout the process.

2.7 Conclusions (Link to below)

This Conclusion summarizes the final recommendations on the feasibility of InnovatioNDistilation's product.

2.1 Product Description (to top)

2.1.1 Physical Description

InnovatioNDistillation has developed an emergency water recovery system.  The product is a water distillation device, which runs solely off of human mechanical input.  Specifically, cycling charges a generator.  Acquired energy is transferred to heat through sequential operation of a heating cartridge and thermoelectric (TE) module.  This heat boils brackish water, which is condensed on the reverse side of the TE for drinking.  The entire system is comprised of three main segments: the frame, gearing and power transmission, and the boiling and distillation system.  These divisions are integrated to provide the structure, energy, and control needed to produce potable water through distillation.  These three systems are discussed briefly.

The frame was constructed through manipulation of a Huffy road cycle.  An indoor bicycle training stand was used to raise the rear tire and provide the needed stability.  An original bicycle frame was chosen for two reasons: first, for its proven mechanical integrity.  A Frame Trade Study was performed to analyze the forces and moments created on a cycling structure.  It was found that a collapsible fabricated frame could be constructed using steel or titanium tubing, but would be heavier and cause lower factors of safety than a purchasable cycle.  Secondly, a road bicycle creates an established geometric advantage in pedaling applications.  To seize the most energy out of the mechanical input through pedaling there is no better human position to be in than that achieved while on a bicycle.  This was discovered through collaboration with cycling specialists.

The power transmission assembly includes the sprocket system and generator.  The Wind Stream and Power 280 W generator was chosen based on its performance in several key areas.  Power output, torque input, and input rotations per minute were several of the essential categories researched (See Generator Trade Study).  The original bicycle sprocket and chain system was utilized.  Also, a large sprocket was attached to the rear wheel and a small sprocket to the generator shaft.  A second chain connected these two and provided the gearing ratio needed to spin the generator shaft at the desired rate.

The distillation system was comprised of the boiler, heating cartridge, thermoelectric (TE) module, condenser, and piping.  The heating cartridge was chosen based on its ability to transfer energy directly to the water within the boiler ( Heating Element Trade Study).  The TE is the crucial interface that assists in boiling the water on the top and condensing the water on the bottom.  With an electrical input the module creates a temperature gradient between its two faces by transferring energy from the cool side to the warm side.  Energy is dissipated as heat during operation which further assists in the boiling process.  The boiler consists of a small thermos and was selected based on its insulation and heat resistant characteristics.  It is also conducive to drilling fabrications necessary to integrate the heating cartridge and TE module.  The condenser was fabricated out of aluminum plating and implements a series of fins housed in a diffusive rectangular box.  The Condenser Trade Study highly influenced the integration of this component by analyzing a range of fin sizes, quantities, and arrangements.

2.1.2 Key Features

The main goal of InnovatioNDistillation was to distill as much water as possible with a provided amount of energy.  Striving to achieve a relative COP of greater than 1, such as that seen in a refrigeration cycle, was important.  This is why the product implements the joint TE module and heating element.  The key feature that controls this system is the sequential operation embedded intelligence.  In order for the TE to work in equilibrium, energy flowing out of the hot side (that in contact with the water) must equal the energy absorbed by the cool side (that in contact with the steam).  If energy is not dissipated at this critical rate than temperatures could become too low or too high and the performance of the TE would be compromised.  To prevent this from occurring, the sequential operation intelligence monitors the temperatures seen on the two sides of the TE.  If critical combinations of temperatures are reached than the input energy from the generator is reverted to the heating cartridge.  This is controlled through series transistors and, in the prototype, a manual switch and LED’s mimic this automation.  Because the TE is the key to maximizing performance, controlling it effectively has also become a key feature of the system.

2.2 Design Relevance (to top)

InnovatioNDistillation has built its emergency water recovery system to assist in and alleviate the primary issues following natural disasters.  Through collaboration with professionals much information was gained:
Natural disasters, as well as some human-caused disasters, lead to human suffering and create needs that the victims cannot alleviate without assistance. Examples of disasters include hurricanes, tornadoes, floods, earthquakes, drought, blizzards, famine, war, fire, volcanic eruption, a building collapse, or a transportation wreck. When any such disaster strikes, a variety of international organizations offer relief to the affected country. Each organization has different objectives, expertise, and resources to offer, and several hundred may become involved in a single major disaster.
Of these many organizations it was found that over half of them assist in providing potable water to victims (Disaster Relief Organization Table).  This is due to the fact that dehydration, hunger, and lack of sanitation are the major causes for death post-disaster.  To give disaster victims more independence and ability to sustain health for longer periods of time InnovatioNDistillation has created the distillation device.  A product such as this could either be bought by those in high disaster-risk areas, or distributed by disaster relief organizations.

Competition in this market includes any product that alleviates dehydration issues in times of disaster.  This includes bottled water and advanced filtering and purification mechanisms, which are currently heavily distributed in times of disaster.  After discussing these issues with professionals from Red Cross it was found that a major problem with current distributions and relief is that supplies run out quickly.  InnovatioNDistillation’s product is suited for continued use and provides a means for unlimited clean water over time.  If distributed by disaster relief organizations than the device can be reused from one relief effort to the next, which would make this product extremely unique.

2.3 Design Process Used (to top)

Much emphasis was placed on achieving an efficient, high quality design process due to the strict budget and rigid time constraints.  Therefore, the design process was broken down into four stages—1) Project Definition and planning, 2) Specification Definition, 3) Conceptual Design, and 4) Prototype Development (See Ullman’s Mechanical Design Process).

2.3.1 Project Definition and Planning

Within this first section of the design process several crucial tasks were performed.  First of all, team positions were assigned such as prototype supervisor and group leader.  This provided responsibility and accountability for each member.  Next, research was performed in several areas of importance, such as distillation and human power generation, to provide the group with background information regarding the project (See Research).  The target market was defined early (Target Market/Goals) along with quantifiable goals to guide upcoming design decisions.  Most important within this phase was the development of a Gantt chart to monitor progress and create internal deadlines for the team (Gantt Chart).  Last of all, a preliminary budget was created to estimate the allocation of the funds provided.

2.3.2 Specification Definition

Still early in the design process was the specification definition section.  Here InnovatioNDistillation identified the customer and researched the prospective of the project.  These two tasks were performed in order to generate the engineering specifications that our product would potentially meet.  Identifying the customer included contacting several disaster relief organizations (Collaboration).  From here it was determined what type and style of product would be useful and for what specific situations it could be applied.  The ASME Design Competition gave a good background for this research (Competition).  Products such as filtration mechanisms, iodine tablets and even bottled water were explored.  This helped the team understand the need for the product.  For example, no product currently on the market could provide an unlimited source of potable water.  These realizations were made parallel with researching the potential of the project.  Issues such as the boiling and distillation processes were analyzed.  Human power production was investigated as well.  Grasping the physics behind each component of the product was necessary for creating realistic engineering specifications.  Following this, these quantifiable engineering specifications were defined (Design Requirements).  These results heavily influenced further design decisions.

2.3.3 Conceptual Design

This section accounts for a large portion of the time committed by team InnovatioNDistillation.  Although this was the third stage in the process, certain aspects were approached right from the beginning such as concept generation.  Each group member created a concept sketch to share during the initial team assembly phase (Initial Concepts).  When defining the market, ideas were continuously being brought up and reflected upon.  Finally, several options were being considered during the development of the engineering specifications that aided in visualizing and quantifying the goals of the project.  It was after this point, however, in which the critical concept evaluation was done.  This primarily involved four trade studies each pertaining to an imperative piece of the project (See Supporting Information – Technical Documentation).  For example, one trade study was done that analyzed the feasibility and applicability of several heating elements to be used within the boiler.  Key product components were continuously being analyzed at this point as well.  For instance, the ability of a thermoelectric module to be used simultaneously as a heating and cooling device was investigated.  Design decisions were continuously being made during this extensive period of formulation and evaluation.  Specific components were selected based on the facts gained from analysis, the updated budgeting information, and the performance speculations.

2.3.4 Prototype Development

The last stage of the design process was the prototype development.  Actual assembly, component integration, and testing and troubleshooting were performed in this phase.  The influence of early design decisions became evident in this stage of the development.  The more work that was done to ensure compatibility of elements early in the design, the more apt they were come together as intended.  In problem areas quick analysis, evaluation, and design decisions had to be made.  For example, the integration of the generator shaft and small sprocket deviated from the original design due to the large clearance and therefore a compatibility-filler was fabricated.  Finally, with a working prototype several performance tests were made. (Testing documentation will appear in the final draft)

2.4 Options Considered (to top)

While making final design decisions there were two major options being considered.  The main difference between the two options concerned the distillation system.  The first option implemented a transcritical refrigeration cycle to power the boiler and condenser, while the second alternative consisted of a thermoelectric module and heating element in its place.  The focus of each was reusing the energy given off by the steam when condensing.  The two competing schematics are seen in figures 1a and b below.

Both designs implement the same power generation system, shown simply in the schematic as a pedal-chain system, which drives a generator.  The key features of each option and the technical difficulties associated with each are shown in table 1.  Notice that while the transcritical refrigeration cycle is a well known technology it would be very expensive and demand the precise integration of multiple components.  The compact and durable thermoelectric solution became the best fit for the application despite the uncertainty of the technology.

Figure 2: Thermoelectric module and Heating element – Option 2

2.5. Solutions and Rationale (to top)

2.5.1 Key Components

After analyzing the feasibility of each option the thermoelectric module was selected.  The product would consist of a 4 x 4 cm TE module that would contact the bottom of the boiler and the top of the condenser to provide a temperature gradient benefiting the operation of both systems.

A cartridge heater will be used to assist the boiling of the water and will work in sequential operation with the TE module.  The heater will be two inches long and be fully submersed in the water to ensure all energy is transferred to the water (Heating Element Trade Study).  The condenser will consist of an array of aluminum fins that will be cooled such that the steam will readily condense after entering.  The precise arrangement was determined in the Condenser Trade Study.  Ten ¼” thick fins are aligned with ¼” gaps to maximize the condensation and ensure the water runs down the sides.  The piping in which the steam will travel from the boiler to the condenser will be well insulated so that no energy is lost through condensation before the condenser is reached.

2.5.2 Strengths and Weaknesses

The design option chosen will be very compact and rugged.  The boiler and condenser integration allows for the mobility of a single unit.  The critical components, including the TE module and heating element, will be tightly integrated to the system and will be resistant to being dropped from at least three feet high.  This option is much less complicated than the transcritical cycle, and therefore removes many unforeseen difficulties that could arise during development.

Although the system is much simpler the technology is relatively new.  There is a potential that essential steam flow rates will not be reached and the TE module will not assist in boiling and condensing as intended.  Although the goal of the sequential operation is to ensure the TE’s success, it is not guaranteed.

2.6 Implementation Details (to top)

As the prototype took form, it became clear that several design items previously assumed to be trivial had become show-stopping:
When welding the 52-tooth sprocket to the existing sprocket relay at the back of the bike, it was known that eccentricity would be critical, but it was not realized until the first test run how even 1 mm of eccentricity could affect the performance of the power generation.  Although a derailer was added to the prototype to compensate for the fluctuating chain tension, the systems performance was nonetheless irreversibly affected.  For future design, the 52-tooth sprocket would be optimally mounted directly to the rear shaft in order to enforce concentricity of the sprockets and constant tension of the chain.
Furthermore, the condenser design was realized to be non-optimal, as water collected in the flat entry diffusion region of the condenser housing.  Although increased insulation around the entry region could prevent most of the steam from condensing in this region, thereby allowing the water to run down to the exit once it condensed on the aluminum fins, all water which would inadvertently condense within the pipe and in the entry region would still collect in this flat entry, requiring the user to tip the condenser and “pour” out the pooled water.  The condenser housing could easily be redesigned to accommodate “downhill” flow of water in the entry region.  Also, the long and narrow exit of the condenser did not allow the water to be easily collected once it ran out of the condenser.  This could be easily remedied by adding a funneled exit.
Finally, the mounting of the small sprocket onto the shaft of the generator proved excessively challenging, as the shaft of the generator was roughly 2 mm smaller than the diameter of the hole in the sprocket.  Even with set screws, simple gap fillers such as shimmies or tape could not efficiently provide a rigid structure to concentrically mount the small sprocket onto the generator shaft.  Eventually, a small plastic ring was created using computer-aided machining, which would concentrically mount the small sprocket.  In the future, a perfectly-machined sprocket would either be purchased or cut in order to match the inner and outer diameters and avoid concentricity issues.

2.7 Conclusions (to top)

The final product was able to boil and condense a significant amount of water for the one hour of energy input to the system.  However, as a marketable product, the user of the bike might sweat more water out of the body than is actually distilled by the system.  Thus, its use as an emergency distillation device might prove the product to be infeasible for its originally stated purpose.  However, the heat-recycling technology developed throughout the design of the system has other implications in global markets.  Although the thermoelectric modules functioned well as raw heating elements for the system, they are meant to function on a temperature gradient to move heat from one side of the TE module to the other.  Because the condenser was designed for the worst case scenario, it was ultimately “too large” for the system capacity, the temperature of the aluminum fins did not increase enough to provide a benefit to the temperature gradient of the TE modules.  A smaller condenser would force the temperature of the fins to increase more, which would improve the performance of the TE modules.  Further research on this technology, specifically the use of TE modules as integrated heat pumps and heating elements, could benefit contemporary water distillation units.