PROJECT INFORMATION
LOCATION
This project focuses on energy saving applications and measures across the Navajo Nation Reservation in Northern Arizona and New Mexico. This region includes cities and towns such as Winslow, Holbrook, Page, and Tuba City, Arizona. At around 27,413 square miles, it is the largest area of land held by a Native American tribe currently in the United States. With a population of only around 350,000, it mostly consists of small towns and rural communities.
CONSTRAINTS
Due to the remote nature of many communities in the Navajo Nation and Hopi Reservations, many residents do not have access to a power grid or running water. Therefore, they are often forced to use coal and wood stoves for home heating. Additionally, many do not have access to substantial disposible income to spend on a state-of-the-art, off the grid renewable energy heating system. Therefore, the team must develop solutions that do not depend excessively on external utilities while remaining affordable to the client and beneficiaries.
TASKS - First Semester
The team was tasked with producing a design that heats a home on the reservation during the winter while minimizing the pollution and health and safety hazards of a wood or coal burning stove. The design must be easy to implement, affordable, and consistently reliable. The team will use energy modeling software to determine the eligibility of design components.
POTENTIAL DESIGNS - first semester
One potential design the team has considered includes a solar air furnace paired with Phase Change Materials. Phase Change Materials (PCMs) act as a thermal battery, storing latent heat from the sun during the day to be released at night when solar energy is not available. This allows the home to take advantage of large amounts of solar thermal energy available during the day and continue to heat the home at night without a need for burning fuel.
Another possible means of achieving safety improvements and pollution reduction includes insulating the structure. This reduces demand on the heat source, so it can work with either a standard coal or wood stove or a solar furnace with or without PCMs. The team must determine the cost effectiveness of an amount of insulation compared to the installation of a new heating system.
energy modeling
To conduct research regarding the viability of different heating concepts, the team elected to use energy modeling software to provide accurate models for different heat source arrangements and home constructions. Based on the current support available at NAU and its modeling capabilities, eQUEST was selected as the software for this project. eQUEST models accept input parameters, such as construction materials of the structure, insulation type and amount, window amounts and locations, and occupancy, and corroborate these values with local weather data to output monthly energy consumption values. The team initially conducted eQUEST models under scenarios systems including PCM to systems without.
Additional modeling in eQUEST considered a variety of different systems without PCM integration, focusing on parameters including insulation location and amount and integration of a solar furnace as a heating source.
first semester CONCLUSIONS
Based on the results from the initial round of eQUEST models, the team determined PCM to be too expensive and ineffective for applications in this project. Therefore, further options for different amounts of insulation and different heat sources were also considered. This further research concluded insulation on all surfaces inside the home to be most effective. Solar furnaces were also deemed to be effective at reducing fuel consumption, but require a high up front cost, so they must be paid for by sponsors or grants.
second semester project changes
Entering the project's second semester, the Red Feather Development Group underwent a change of management and consequentially, the project goals changed substantially. Over the summer, Red Feather had the chance to purchase, ship, and install solar furnaces produced by YourSolarHome, a Canadian manufacturer. The team was tasked with designing and constructing a solar furnace with comparable or superior effectiveness to the Canadian design. This design should be able to be manufactured by Red Feather to reduce the cost and logistic difficulty produced by shipping products from Canada.
proposed designs - second semester
To approximate the effectiveness of the YourSolarHome SolarSheat GS1500 solar furnace, the team elected to design and build a 4 ft. by 8 ft., wood framed furnace with air circulation powered by a fan. To test internal ducting solutions, the team built 4 different 1 ft. by 2 ft. prototypes.
The 4 designs consisted of a control with no ducting, a design with a single twisting aluminum duct, a design with multiple aluminum cans lined up as ducting, and a design with diagonally mounted steel slats.
TESTING PROCEDUREs
The testing procedure the team used consisted of setting up the furnaces in direct sunlight and measuring temperatures at different locations on the furnaces. Three thermocouples were mounted on each device to measure internal temperature, inlet temperature, and outlet temperature. They were attached to an Arduino UNO to translate thermocouple readings into readable data.
results and conclusions
The team concluded from testing that the steel slat design provided the greatest effectiveness as a heat exchanger as it has the highest outlet temperatures. It also makes the most practical sense because it is fairly cheap and easy to manufacture. This design provides a far better return on investment than the purchased model, so would possibly be a feasible option for Red Feather.
SCHEDULE AND BUDGETING
The team concluded both semesters' work on schedule and under the maximum budget. Due to budget constraints, the team was unable to build the full-scale solar furnace model. However, this model is detailed in the operations and assembly manual and calculations.
IMAGE CITATIONS
Figure 1: Map of Navajo Reservation in Arizona
The Navajo Reservation, Into America, 2013. [Online].
Figure 2: System Concept with PCM Battery and Solar Collector
Figure 3: Solar Collector Example
Heat Recovery Collectors, Trigo Energy, 2018. [Online].
Figure 4: eQUEST 3D Home Model
Figure 5: Solar Furnace Models
Figure 6: Solar Furnace CAD Model
Figure 7: Solar Furnace Testing Procedure