Experimental demonstration and model-based optimization of adsorption heat transformation for waste heat upgrading; 1. Auflage
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| Title: | Experimental demonstration and model-based optimization of adsorption heat transformation for waste heat upgrading; 1. Auflage |
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| Authors: | Engelpracht, Mirko |
| Publisher Information: | RWTH Aachen University, 2024. |
| Publication Year: | 2024 |
| Subject Terms: | adsorption heat transformer, demonstration of experimental feasibility, dynamic modeling with Modelica, model calibration and validation, multi-objective process design optimization, Hochschulschrift |
| Description: | Limiting climate change requires drastically reducing anthropogenic greenhouse gas emissions. About 20 % of global CO2 emissions are caused by industrial heat supply. Hence, research on technologies to decarbonize industrial heat supply is imperative. Adsorption heat transformers (AdHTs) that use a closed-loop cycle have been recently discussed for sustainable industrial heat supply. AdHTs provide useful heat by exploiting low-temperature waste heat as the main driving energy and transforming a fraction of this heat to a higher temperature level. However, the assessment of AdHTs has been based on basic thermodynamic equilibrium models, particularly lacking the following: (1) Neither have achievable power densities been investigated, (2) nor has the experimental feasibility been demonstrated. Hence, this thesis addresses both research gaps by combining experiments, dynamic modeling, and mathematical optimization. Thereby, the research focus is on heat upgrading around 100 °C. First, an ideal dynamic AdHT model was developed. It was shown that the adsorber heat exchanger design critically influences the performance indicators of the AdHT and must be carefully tailored to the operating temperatures. This tailoring allowed to achieve exergetic efficiencies of 0.64 J_th/J_th and power densities of 590 W/kg. Then, a one-bed AdHT prototype was developed and used to successfully demonstrate the experimental feasibility of heat upgrading: The exergetic efficiency was 0.23 J_th/J_th, the thermal efficiency was 0.18 J_th/J_th, and the power density was 168 W/kg. The prototype was systematically investigated for 57 operating points, showing avoiding condensation of adsorptive on the adsorber casing and heat losses to be imperative. For further investigations, a detailed model of the AdHT prototype was developed that includes all significant effects while being robust for design optimization. The model was successively calibrated, and a high model quality was demonstrated by validation with all experimentally investigated operating points: Predicted performance indicators deviated on average by 8.1 % from values calculated from measured data. Finally, various process design optimizations were performed. An improved prototype design achieved thermal efficiencies of 0.35 J_th/J_th and power densities of 304 W/kg. A two-bed AdHT with different recovery strategies further increased thermal efficiency to 0.40 J_th/J_th. Furthermore, modeling the main electrical consumers of AdHTs showed that an electrical efficiency of 40 J_th/J_el is achievable at a nominal heat flow of 500 kW.In summary, this thesis increases the technology readiness level of AdHTs upgrading heat around 100 °C from level 2 to 4. Dissertation, RWTH Aachen University, 2024; Aachen : Wissenschaftsverlag Mainz GmbH, Aachener Beiträge zur technischen Thermodynamik 51, 1 Online-Ressource : Illustrationen (2024). = Dissertation, RWTH Aachen University, 2024 Published by Wissenschaftsverlag Mainz GmbH, Aachen |
| Document Type: | Book |
| Language: | English |
| DOI: | 10.18154/rwth-2024-06878 |
| Accession Number: | edsair.doi...........87f085a572872133a9675a2c7487d0f2 |
| Database: | OpenAIRE |
Nájsť tento článok vo Web of Science | Abstract: | Limiting climate change requires drastically reducing anthropogenic greenhouse gas emissions. About 20 % of global CO2 emissions are caused by industrial heat supply. Hence, research on technologies to decarbonize industrial heat supply is imperative. Adsorption heat transformers (AdHTs) that use a closed-loop cycle have been recently discussed for sustainable industrial heat supply. AdHTs provide useful heat by exploiting low-temperature waste heat as the main driving energy and transforming a fraction of this heat to a higher temperature level. However, the assessment of AdHTs has been based on basic thermodynamic equilibrium models, particularly lacking the following: (1) Neither have achievable power densities been investigated, (2) nor has the experimental feasibility been demonstrated. Hence, this thesis addresses both research gaps by combining experiments, dynamic modeling, and mathematical optimization. Thereby, the research focus is on heat upgrading around 100 °C. First, an ideal dynamic AdHT model was developed. It was shown that the adsorber heat exchanger design critically influences the performance indicators of the AdHT and must be carefully tailored to the operating temperatures. This tailoring allowed to achieve exergetic efficiencies of 0.64 J_th/J_th and power densities of 590 W/kg. Then, a one-bed AdHT prototype was developed and used to successfully demonstrate the experimental feasibility of heat upgrading: The exergetic efficiency was 0.23 J_th/J_th, the thermal efficiency was 0.18 J_th/J_th, and the power density was 168 W/kg. The prototype was systematically investigated for 57 operating points, showing avoiding condensation of adsorptive on the adsorber casing and heat losses to be imperative. For further investigations, a detailed model of the AdHT prototype was developed that includes all significant effects while being robust for design optimization. The model was successively calibrated, and a high model quality was demonstrated by validation with all experimentally investigated operating points: Predicted performance indicators deviated on average by 8.1 % from values calculated from measured data. Finally, various process design optimizations were performed. An improved prototype design achieved thermal efficiencies of 0.35 J_th/J_th and power densities of 304 W/kg. A two-bed AdHT with different recovery strategies further increased thermal efficiency to 0.40 J_th/J_th. Furthermore, modeling the main electrical consumers of AdHTs showed that an electrical efficiency of 40 J_th/J_el is achievable at a nominal heat flow of 500 kW.In summary, this thesis increases the technology readiness level of AdHTs upgrading heat around 100 °C from level 2 to 4.<br />Dissertation, RWTH Aachen University, 2024; Aachen : Wissenschaftsverlag Mainz GmbH, Aachener Beiträge zur technischen Thermodynamik 51, 1 Online-Ressource : Illustrationen (2024). = Dissertation, RWTH Aachen University, 2024<br />Published by Wissenschaftsverlag Mainz GmbH, Aachen |
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| DOI: | 10.18154/rwth-2024-06878 |