Self-thermal insulation of containers by the precipitation and formation of a gas film at the walls for thermal energy storage
Passive thermal self-insulation of the inside walls of containers when they are deliberately coated by nucleation sites and the fluid is diluted with a certain gas. It is well known -in heat transfer engineering, the drastic thermal insulating effect produced when a film of vapour (film boiling) cov...
| Authors: | , |
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| Format: | article |
| Publication Date: | 2023 |
| Country: | España |
| Institution: | Universitat Politècnica de Catalunya (UPC) |
| Repository: | UPCommons. Portal del coneixement obert de la UPC |
| Language: | English |
| OAI Identifier: | oai:upcommons.upc.edu:2117/385253 |
| Online Access: | https://hdl.handle.net/2117/385253 https://dx.doi.org/10.1115/1.4056977 |
| Access Level: | Open access |
| Keyword: | Energy storage Energy transfer Thermodynamics Energy systems Heat and mass transfer Heat transfer enhancement Energia -- Emmagatzematge Transferència d'energia Termodinàmica Àrees temàtiques de la UPC::Energies::Tecnologia energètica Àrees temàtiques de la UPC::Física::Termodinàmica::Física de la transmissió de la calor |
| Summary: | Passive thermal self-insulation of the inside walls of containers when they are deliberately coated by nucleation sites and the fluid is diluted with a certain gas. It is well known -in heat transfer engineering, the drastic thermal insulating effect produced when a film of vapour (film boiling) covers the surface of the heater, and if measures are not taken the burnout of the heated surface occurs. This, until now, undesired phenomenon, however, may be harnessed for thermal storage. Here, it is proposed that a self-passive film-gas blanketing the inside surfaces of the container may be promoted by the dilution of a given gas in the fluid in which the heat is to be stored (e.g, molten salts, water, phase change materials, etc.) and deliberately covering the inside surface of the container with nucleation sites. The amazing achievements in last years in micro/nano surface modification allow the control in size, number and roughness of the nucleation sites making the idea of self-thermal insulation by a film-gas of potential interest for thermal storage. Utilizing a simplified geometrical and physical model an expression for the average thickness of the film-gas and the heat transfer coefficient was derived. It was shown that a stable film-gas with average thickness 50µm may be promoted and with an overall heat transfer coefficient reduced to 65 per cent compared to that without film-gas |
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