{"title":"Design and modeling of area-enhanced, bi-porous, evaporative macrochannel for building facade cooling.","authors":"Gautier Rouaze, Zhengmao Lu","doi":"10.1038/s44435-026-00021-6","DOIUrl":"10.1038/s44435-026-00021-6","url":null,"abstract":"<p><p>Facade-integrated evaporative cooling offers a pathway to high heat rejection for buildings with limited rooftop area. However, it needs to operate under fixed footprint and parasitic power constraints, requiring surface enhancement strategies that enable more efficient heat removal. We develop a fan-power-constrained conjugate heat-mass transfer framework to evaluate facade-integrable evaporative macrochannels. We show that hydrogel-only pin fins enhance evaporation into channels but provide little increase in base heat removal due to high internal thermal conduction resistance. To overcome this bottleneck, we introduce a Hydrogel Overlayer on Metal Scaffold (HOMeS) architecture that separates heat spreading and capillary wetting across pore scales. Bayesian optimization identifies near-optimal pin-fin geometries, which, for a 200 × 200 mm panel at a fan power density of 125 Wm<sup>-2</sup>, deliver ~7 × higher base heat removal than a flat evaporating channel. We demonstrate that evaporative texturing provides significant performance improvement only when thermal coupling to the interface is preserved.</p>","PeriodicalId":524255,"journal":{"name":"Npj thermal science and engineering","volume":"1 1","pages":"19"},"PeriodicalIF":0.0,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13671269/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149218049","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Diana I Nikolova, Rachel Tuffin, Mengfan Guo, Neil D Mathur, Xavier Moya, Peter Tipping, Richard J Mandle, Helen F Gleeson
{"title":"Ferroelectric nematic liquid crystals: temperature-tunable electrocaloric fluids with large strength at low fields.","authors":"Diana I Nikolova, Rachel Tuffin, Mengfan Guo, Neil D Mathur, Xavier Moya, Peter Tipping, Richard J Mandle, Helen F Gleeson","doi":"10.1038/s44435-026-00019-0","DOIUrl":"10.1038/s44435-026-00019-0","url":null,"abstract":"<p><p>The electrocaloric (EC) effect offers a promising energy-efficient and clean cooling technology. We present the first direct measurements of EC temperature change in a new family of EC fluids, ferroelectric nematic liquid crystals (FNLCs), demonstrating in two such materials temperature jumps of <i>|</i>Δ<i>T</i> <sub><i>j</i></sub> <i>|</i> ~ 0.2 K for field changes as low as Δ<i>E</i> ~ 0.1 V μm<sup>-1</sup>. Indirect measurements of adiabatic temperature change <math><mrow><mi>|</mi> <mi>Δ</mi> <mi>T|</mi></mrow> </math> confirm that these direct measurements are an underestimate and that Δ<i>E</i> = 2 V μm<sup>-1</sup> can induce up to <i>|</i>Δ<i>T</i> <sub><i>j</i></sub> <i>|</i> ~ 1.6 K, yielding EC strengths <i>|</i>Δ<i>T/</i>Δ<i>E|</i> up to 100% higher than incumbent materials. For temperature spans of 5-10 K, we predict a coefficient of performance of ~21-40. We find |Δ<i>T|~1</i> K for >100 FNLCs that collectively span all temperatures between 0 ˚C and 100 ˚C. This, together with the new device concepts conceivable with fluid EC materials, offers huge potential for cooling applications.</p>","PeriodicalId":524255,"journal":{"name":"Npj thermal science and engineering","volume":"1 1","pages":"18"},"PeriodicalIF":0.0,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13671268/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149218083","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}