Flue Gas Energy Recovery

The University of Idaho Steam plant switched to a biomass fired boiler in the 1980's which increased steam capacity and replace the existing coal and natural gas boilers. These boilers produce a large amount of waste flue gas heat that our team is tasked with recovering and using to produce electricity.

Background
The Steam Plant:
 * The University of Idaho Steam plant is full of hot surfaces that constantly put out heat. Our teams goal is to capture this waste heat by a device that utilizes Thermoelectric Generators (TEGs) to produce an output voltage via a Temperature difference.

What is a Thermoelectric Generator(TEG):

 * A device that utilizes heat flux to produce electricity
 * Constructed of n-type and p-type semiconductors formed into thermocouples
 * Common efficiency between 5% to 9%
 * For max efficiency ΔT must be around 518 F

How a TEG works:

 * Operate according to the Seebeck Effect.
 * Temperature difference across thermoelectric material can be converted directly into electrical power



Heat Transfer equations

 * Conduction: q=-k(ΔT/Δz)
 * k=thermal conductivity, T=temperature (°C or K), z=thickness


 * Free convection: q=hA(T_surf-T_ambient)
 * h=heat transfer coefficient, A=area, T=temperature


 * Radiation: q=σ*ξ*A*(((T_1)^4)-((T_2)^4))
 * σ=5.67e-8(W/(m^2 K^4)), ξ=emissivity (unitless), A=area, T=temperature(Kelvin)

Circuit Equations

 * OHMS Law: V = I*R
 * Power: P = V*I = (I^2)*(R) = (V^2)/R
 * V=voltage(Volts)
 * I=current(Amps)
 * R=resistance(Ohms)
 * P=power(Watts)

Proof of Concept

 * For our teams initial testing we where able to get some TEGs from a past senior design project, some old heatsinks, and a hotplate from the chemistry department here at the University of Idaho.


 * For test 1 we used a heat gun, heatsink and a thermal camera to get our hot and cold sides and to determine what the temperatures where on both. We felt as though there might be some error in the measurments because of the reflection on the thermal paper and using a heat sources that is radiation and not a hot surface.


 * For test 2 we where able to get a lot better test setup with a hot plate, thermocouples hooked up to multimeters and pressure applied to the TEGs. The results shown in each of the pictures to the right show a slightly better output with similar temperature differences.





Meeting Minutes

 * [[Media:Minutes 9-15-16.pdf| September 15th 2016 ]]
 * [[Media:Minutes 9-21-16.pdf| September 21th 2016 ]]
 * [[Media:Minutes 9-28-16.pdf| September 28th 2016 ]]
 * [[Media:Minutes 10-5-16.pdf| October 5th 2016 ]]
 * [[Media:Minutes 10-12-16.pdf| October 12st 2016 ]]
 * [[Media:Minutes 10-19-16.pdf| October 19th 2016 ]]
 * [[Media:Minutes 11-2-16.pdf| September 2nd 2016 ]]