Title: Natural Gas Heating Season Report
Author: Canadian Gas Association
Summarized by Mythili
- The total CGA member company active customer base
for natural gas is just over 7.1 million end use locations.
- Over 6.5 million households in Canada use
natural gas as their primary heating source. That is more than electricity, heating oil, or propane.
- Natural gas is often a more affordable and cleaner option
than heating oil, propane or grid electricity generated from coal-fired
facilities.
Title: A comprehensive review of Thermoelectric Generators:Technologies and common applications
Author(s): Nesrine Jaziri, Ayda Boughamoura, Jens Müller,Brahim Mezghani, Fares Tounsi, Mohammed Ismail
Summarized by Mythili
- Thermoelectric generators (TEGs) have demonstrated their ability to directly convert thermal energy into electrical via the Seebeck effect.
- They are environmentally friendly because they do not contain chemical products, they operate silently because they do not have mechanical structures and/or moving parts, and they can be fabricated on many types of substrates like silicon, polymers, and ceramics.
- TEGs have a long operating lifetime.
Title: Modeling and Application of a Thermoelectric Generator
Author(s): David Yan
Summarized by Mythili
- Waste heat is heat produced as a by product in power generation, industrial processes, and electrical machines, among others.
- Vast amounts of waste heat are produced by industry.
- Recovering this heat into usable electricity would save a significant amount of money through increasing efficiency and lowering fuel costs as well as being beneficial to the environment.
- However, since such a large amount of energy is freely available, the engineering problem then becomes one of economics, and choosing the technology and configuration which produces the best utilization of heat.
Title: Thermoelectric Device Wraps Around Hot Pipes to Generate Electricity
Author(s): Ben Coxworth
Summarized by Mythili
- A new wrap-around device, created via a collaboration between Pennsylvania State University and the National Renewable Energy Laboratory is made up of multiple flat, square modules known as couples.
- It consists of 12 rectangular strips of six couples each, with a flexible metal foil substrate electrically connecting those strips to one another.
- This design allows the 72-couple device to be wrapped around hot water pipes – or other types of pipes that get hot – in a home, factory, or anyplace else.
- When applied to a hot gas flue pipe the prototype is claimed to have exhibited the highest-ever reported output power and device power density from a single thermoelectric generator.
Title: Power Module Installation Notes
Author(s): TEC Solidstate Power Generations
Summarized by Mythili
- TEG power modules have large thermal expansion characteristics while in operation.
- Therefore, proper compression and mounting are paramount for long-life trouble-free operation.
- The hot side must be in excellent contact with a heat source and cold side must be thermally touching and compressed against a heat exchanger that can remove the heat effectively away from the cold side face of the module in order to create a large Delta T.
- It is imperative that the module be installed correctly with the hot side face attached to the heat generating device.
- Failure to do this procedure will result in the destruction of the module.
- The cold side should always be engaged when heat is being applied.
Title: Waste heat recovery from thermo-electric generators (TEGs)
Author(s): L.S. Hewawasam, A.S. Jayasena, M.M.M. Afnan, R.A.C.P. Ranasinghe, M.B. Wijewardane
Summarized by Mythili
- This study is conducted to understand the possibility of integrating the TEG to the muffler of an engine.
- The thermo-electric modules (TEMs) can be easily integrated to the muffler and electricity can be conveniently generated using the exhaust energy available in the hot exhaust gas.
- The power generation by the TEG coupled to the exhaust muffler increases when increasing the exhaust gas temperature.
- When the TEG integrates to the exhaust muffler, waste heat can be recovered without sacrificing additional back pressure in the engine exhaust system.
- Use of efficient Thermoelectric materials to fabricate the TEG and integrate it with the muffler, will result in designing efficient TEGs without adding extra back pressure to the engine.
Title: Evaluation of the Performance of the SP 1848-27145 Thermoelectric Generator Module
Author(s): Collins E. Ouserigha, Ayibapreye K. Benjamin
Summarized by Mythili
- A simple thermoelectric generator (TEG) has been designed and constructed using the Bismuth Telluride-based SP1848-27145 generator module.
- Measurements taken from the constructed generator show that as the temperature rises, the current and voltage output increases until the difference in temperature between the hot and cold side of the generator module reaches 70 degrees Celsius
- At this maximum temperature difference of 70 degrees Celsius, the maximum voltage output of 2.20 V was measured.
- The output voltage was stepped-up with a dc-to-dc voltage booster to 5.0 V, which can be used to power portable devices (such as ultra-bright LED lights, charging of cell phones) and other devices that runs on a 5 V supply.
Title: A primer on heating systems
Author(s): Alex Wilson
Summarized by Mythili
- Forced air heats the fastest.
- Forced air is the most common type of heating system in North America.
- Gas furnaces are among the most efficient.
- Because the flue gases are relatively cool, plastic pipe is sometimes used for side venting.
- Condensing-gas furnaces are the highest-efficiency gas furnaces and have such efficient heat exchangers that flue gases cool down enough for water vapor to condense into liquid.
- When the water vapor condenses, it releases its latent heat, which boosts energy performance.
- Annual fuel utilization efficiency (AFUE) for condensing furnaces typically can range from 90% to 97%.
- Flue gases are usually vented out through plastic piping. Condensate is piped to a floor drain.
Title: How does a gas furnace work?
Author(s): Robert Maxwell
Summarized by Mythili
- Cold air from your house enters the furnace, where the burning gas warms it within the heat exchanger.
- Exhaust from the combustion is piped out of the furnace through the vent and exits the home via an exhaust pipe.
- The warm air is directed into various parts of your house by the blower fan, depending on where thermostats detect the need for heat.
- Parts of a gas furnace:
- Thermostat
- Burners: Small outlets where gas emits within the furnace and is ignited into even, controlled flames.
- Igniter: The device responsible for lighting the gas emitted from the burners. Furnace igniters work by creating a spark to cause ignition, or by producing an extremely hot surface that ignites the gas as it passes.
- Blower fan: A small electric fan and motor that directs warm air from the furnace to various parts of the home according to heat demands.
- Heat exchanger: A series of thin-walled metal tubes that keep the combustion process separate from the air entering the home via the blower fan. Cold air is blown over the outside of the heat exchanger, warming it before it is redirected into the home.
Title: The Development of a Thermoelectric Generator (TEG) Concept for Recycling Waste Heat into Electricity
Author(s): Justin J. Riggio
Summarized by Mythili
- The Seebeck effect is an electromotive force or voltage that can be generated when a temperature gradient is imposed between the junctions of two dissimilar electrical conductors.
- The Seebeck and Peltier effects are reversible.
- Thermoelectric modules (TEMs) are practical devices that are fabricated using thermoelectric materials with the purpose of converting significantly more heat into electricity.
- In such a device, n-type and p-type materials are connected electrically in series and thermally in parallel, and joined together by interconnects, all between two substrates.
- There are issues that reduce the performance of thermoelectric modules, but some promising techniques/approaches to overcome them.
- The semi-conductor/metal junction exhibits a greater electrical resistance that a metal-metal junction, with greatly affects the performance of the device.
- Heat loss, especially thermal contact resistance is another major factor.
- Thermal expansion also needs to be considered
- Mechanical stresses due to a mismatch between the n- and p- elements can lead to failure from crack initiation and propagation.
- Using waste heat as a source reduces the cost by eliminating the need for fuel.
Title: Engineering Scoping Study of Thermoelectric Generator Systems for Industrial Waste Heat Recovery
Author(s): U.S. Department of Energy
Summarized by Mythili
- Roughly a third of the energy consumed by the U.S. manufacturing industry is discharged as thermal losses to the atmosphere or to cooling systems.
- This lost or waste energy (heat) is estimated to be equivalent to more than 1.72 billion barrels of oil or 127 days worth of imported crude oil supply.
- Thermoelectric (TE) materials, discovered in 1821, are semiconductor solids that produce an electric current when joined together and subjected to a temperature difference across the junction.
- This property makes it possible to produce direct current electricity by applying waste heat on one side of a TE material, while exposing the other side to lower ambient temperature surroundings.
- Recovering waste heat is financially sound when practical and economic recovery technologies are available and an identifiable use for the recovered energy is readily available.
- A large portion of industrial waste heat is contained in gases which are discharged at ~300 degrees Fahrenheit.
- This temperature range represents very low quality heat and currently no commercially viable means to recover this energy is available.
- There are several significant opportunities for thermoelectric recovery of waste heat. TEG application in glass furnaces alone, which represent about 1% of industrial waste heat losses, would generate over $25,000,000 in annual sales, assuming higher efficiency TEGs.
Title: Thermoelectric Generator (TEG) Technologies and Applications
Author(s): Hussam Jouhara, Alina Zabnienska-Gora, Navid Khordehgah, Qusay Doraghi, Lujean Ahmad, Les Norman, Brian Axcell, Luiz Wrobel, Sheng Dai
Summarized by Mythili
- When generating electricity in power stations, around two thirds of the energy is lost in the form of waste heat that it is discharged from cooling towers.
- As a result, only about 1/3 of the energy released from the fuel actually ends up in the transmission lines leaving the power plant.
- The ability to collect the heat wasted within these processes and convert it to usable electrical power would enormously increase the efficiency of power generation.
- The reduction of greenhouse emission from the reduced wastage would be beneficial for the environment as less fuel is burned for the same amount of electricity produced.
- Thermoelectric generator (TEG) systems have attracted great consideration in the recovery of waste heat due to their incomparable advantages.
- TEGs provide an opportunity to generate electrical energy from heat energy without the need for moving parts such as turbines, which eliminates extra costs resulting from maintenance and replacement.
- TEGs are also environmentally favourable as they operate with no sound pollution.
- Conversely, TEGs do have a low energy conversion efficiency and require a relatively constant heat source, which are disadvantages.
- Mostly, TEG systems consist of three key elements:
- A heat exchanger (HEX): This absorbs the heat and transfers it into the thermoelectric modules.
- Thermoelectric modules (TEMs): The TEMs generate electricity when a temperature difference exists between their ends.
- A heat sink: In order to dissipate the additional heat from the thermoelectric modules.
- Well-designed solutions can solve the low performance problem and offer substantial economic or environmental added benefit.