Design the Best Possible Thermoelectric Generator System?
- Cold side will require a well designed liquid sink. Not just any liquid sink but a low flow design (under 2 liters per minute of flow). This low flow will reduce power requirements for the pump. The flow should be in parallel not serial to preserve DT to all the modules populated on the liquid sink. Parallel flow allows for all the modules to be exposed to the same thermal input temperature. This is a critical design consideration because if one module is exposed to elevated cold side temperatures and it is in series electrically with other modules that module will influence the power output for that array or bank of modules.
- Hot Side Requires the best possible heat absorber with lots of surface area if possible or an Anodized plate to accept and absorb maximum heat flow before it passes and goes into the environment. You will always have heat dissipating to atmosphere, the trick is to limit that loss as much as possible. A dense heat sink with lots of fins densely (anodized) is the best but not always possible. In a heat sink case heat is absorbed and concentrated close to the module array limiting heat flux travel to the modules hot side surfaces, the shorter the path the better. If the heat path is to long than the thermal resistance of the material will limit the ability for it to reach its target and dissipate to environment before it can be fully adsorbed.
- Module the correct module for the project must be selected. Don’t use a Peltier module is you want to produce large amounts of power (enough to charge a cell phone) as an example. They are not designed for Seebeck Power Generation. Use the TEG modules with specific characteristics TEG1 series for 320°C and below TEG1-PB series for application above 250°C to 320°C, CMO Cascade modules up to 600 °C and soon up to 750°C. And CMO Oxide alone up to 800°C.
- Choosing a TEG1 series module If you are designing an application that has a hot side maximum of 320°C than use a TEG1-12610-5.1, TEG1-4199-5.3, TEG1-1263-4.3, or TEG1-12611-6.0 for liquid cooling. This is because these modules move heat quicker because they are thinner. Less semiconductor thermally faster heat flow. And because liquid can remove large heat fluxes rapidly means more heat flow resulting in more power produced. If the design is using air cooling with a heat sink and fan use TEG1-12610-4.3, TEG1-1268-4.3, and TEG1- 12611-8.0.
- Choosing a TEG1 series TEG1B-12610-5.1 is a Boutique semi-conductor. Specifically, designed for very high hot side temperatures in the 260°C to 320°C range. These temperatures are easily reached when you have a large high heat source but are only using a few (4) at most modules in your design, AND are using a heat sink and fan. Two factors explain why the above statement is true. Firstly, the heat sink cannot move a lot of heat away therefore; the hot side stays hot because heat flow is limited by the method of removal. The second, because you are using a couple of modules they cannot transfer large amounts of heat by themselves thereby, the absorbing plate will not lose it’s temperature and the difference between the source temperature and the hot plate of the TEG system will be very close.
- Choosing a TEG1-PB series TEG1-PB-12611-6.0 these modules are optimized at temperatures in the 250°C to 340°C range and offer ideal performance when a sophisticated design is required with a large heat source and lots of power is required. This can be achieved using flowing water with a direct wood fire contacting the hot side. No Steel or Cast Iron barrier as these materials creates large resistances to heat flow.
- CMO based module are required when you have above average heat sources. Examples are Incinerators and flare gas from well sites or exhaust manifolds directly off of a gas engine of a car or truck. CMO Cascade or Oxide take advantage of these heat sources and are able to survive these ultra high temperatures where other modules would fail quickly.
- Smart MPPT Charger The power coming from the TEG system requires a method of regulation. Ideally the best efficiency from a TEG Thermoelectric generator is when the resistance of the modules array is less or equal to the resistance of the load. The load is either the battery bank or motors, lights, etc. This is critical for maximum power production. Without this Smart controller/ charger it is almost impossible to achieve the best possible efficiency from the TEG Generator. It is also critical to design the least amount of modules in series to reduce Ohm resistance to a minimum.
- Battery Condition If the batteries you are using are old and cannot accept a charge and have high resistance it does not matter how well you TEG system works, you will not be able to fully charge your batteries. It is critical to maintain your batteries to perform the best. TEG systems are ideal for battery life as they charge continually and batteries life spans are extended by 20 to 30%. Continually charging the battery extends the life. Unlike, solar that charges batteries for only a short period of time. The batteries are than drawn down and have to be recharged. This up and down process reduces the life of batteries. Reducing voltage draw down cycles reduces the buildup of sulfate in the battery, extending battery life.