Modeling Energy Recovery Using Thermoelectric Conversion Integrated with an Organic Rankine Bottoming Cycle
Hot engine exhaust represents a resource that is often rejected to the environment without further utilization. This resource is most prevalent in the transportation sector, but stationary engine-generator systems also typically do not utilize this resource. Engine exhaust is a source of high grade thermal energy that can potentially be utilized by various approaches to produce electricity or to drive heating and cooling systems. This paper describes a model system that employs thermoelectric conversion as a topping cycle integrated with an organic Rankine bottoming cycle for waste heat utilization. This approach is being developed to fully utilize the thermal energy contained in hot exhaust streams. The model is composed of a high temperature heat exchanger which extracts thermal energy for driving the thermoelectric conversion elements. However, substantial sensible heat remains in the exhaust stream after emerging from the heat exchanger. The model incorporates a closely integrated bottoming cycle to utilize this remaining thermal energy in the exhaust stream. The model has many interacting parameters that define combined system quantities such as overall output power, efficiency, and total energy utilization factors. In addition, the model identifies a maximum power operating point for the system. That is, the model can identify the optimal amount of heat to remove from the exhaust flow to run through the thermoelectric elements. Removing too much or too little heat from the exhaust stream in this stage will reduce overall cycle performance. The model has been developed such that heat exchanger UAh values, thermal resistances, ZT values, and multiple thermoelectric elements can be investigated in the context of system operation. The model also has the ability to simultaneously determine the effect of each cycle design parameter on the performance of the overall system, thus giving the ability to utilize as much waste heat as possible. Key analysis results are presented showing the impact of critical design parameters on power output, system performance and inter-relationships between design parameters in governing performance.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 964224
- Report Number(s):
- PNNL-SA-61677; JECMA5; 400403209; TRN: US200922%%148
- Journal Information:
- Journal of Electronic Materials, 38(7):1206-1213, Vol. 38, Issue 7; ISSN 0361-5235
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
30 DIRECT ENERGY CONVERSION
BOTTOMING CYCLES
COOLING SYSTEMS
DESIGN
EFFICIENCY
ELECTRICITY
ENERGY RECOVERY
ENGINES
HEAT EXCHANGERS
HEATING
PERFORMANCE
THERMOELECTRIC CONVERSION
TOPPING CYCLES
TRANSPORTATION SECTOR
WASTE HEAT
WASTE HEAT UTILIZATION
NESDPS Office of Nuclear Energy Space and Defense Power Systems
Waster Heat Recovery
Thermoelectric Generator
Rankine Cycle