Abstract
Supercritical CO2 (sCO2) power cycles are being developed due to their potential for high efficiency and reduced capital cost. It is necessary that these recuperators operate at high pressures and temperatures, up to 30 MPa and 900 K, with effectiveness values > 95% and pressure drops <1% to achieve high cycle efficiencies. Moreover, it is also necessary to have reasonable cost recuperators to control the capital costs of the sCO2 power cycles. In this study, a Plate Pin-Fin (PPF) heat exchanger has been proposed as an sCO2 recuperator. This preliminary recuperator design leverages capabilities enabled by additive manufacturing. Although the PPF design has characteristics similar to those of a plate heat exchanger, small diameter and relatively long fins are used to increase surface area, enhance heat transfer, and provide structural support for the partition plates that separate the fluid streams. Existing correlations for heat transfer and pressure drop were adapted for the PPF heat exchanger. These correlations were implemented in a 1D analytical model and used for the optimization of a 5-kWth high temperature recuperator for an indirect sCO2 cycle by varying the design parameters to minimize the quantity of material required. A 3D conjugate heat transfer numerical simulations were conducted to validate the heat transfer and pressure loss correlations. A steepest descent method was used to minimize heat exchanger mass for a 5-kW prototype recuperator subject to a maximum specified pressure drop. The design analysis indicated that an optimum PPF recuperator would be attained for the minimum allowable pin transverse spacing, minimum pin width, minimum pin height and near maximum cell aspect ratio. At a low material requirement of 0.216 kg/kW and a pressure drop, which is almost five times lower than the allowable pressure drop design target, the optimized PPF heat exchanger has the high potential to be an alternative to a printed circuit heat exchanger, which is a conservative design basis for the current state-of-the-art sCO2 recuperators.
| Original language | English |
|---|---|
| Article number | 123961 |
| Journal | Energy |
| Volume | 251 |
| DOIs | |
| State | Published - Jul 15 2022 |
Funding
This project was funded by the United States Department of Energy , National Energy Technology Laboratory , in part, through a site support contract. Neither the United States Government nor any agency thereof, nor any of their employees, nor the support contractor, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof. This work was performed in support of the U.S. Department of Energy's Fossil Energy Crosscutting Technology Research Program. The effort at UT-Battelle, LLC, was conducted under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy for the project “Novel Recuperator Concepts for Supercritical CO 2 based on Additive Manufacturing,” and has been funded by the DOE Office of Energy Efficiency and Renewable Energy, Office of Fossil Energy . The authors would also like to thank Keith Carver and Fred List III of ORNL for providing the size limits for AM fabrication. This project was funded by the United States Department of Energy, National Energy Technology Laboratory, in part, through a site support contract. Neither the United States Government nor any agency thereof, nor any of their employees, nor the support contractor, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.This work was performed in support of the U.S. Department of Energy's Fossil Energy Crosscutting Technology Research Program. The effort at UT-Battelle, LLC, was conducted under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy for the project ?Novel Recuperator Concepts for Supercritical CO2 based on Additive Manufacturing,? and has been funded by the DOE Office of Energy Efficiency and Renewable Energy, Office of Fossil Energy. The authors would also like to thank Keith Carver and Fred List III of ORNL for providing the size limits for AM fabrication.
| Funders | Funder number |
|---|---|
| U.S. Department of Energy | DE-AC05-00OR22725 |
| Office of Fossil Energy | |
| Office of Energy Efficiency and Renewable Energy | |
| Oak Ridge National Laboratory | |
| National Energy Technology Laboratory |
Keywords
- Additive manufacturing
- Analytical model
- Novel heat exchanger design
- Recuperators
- Supercritical carbon dioxide
- sCO2 power cycles
