???? https://goo.gl/images/NVx1hG Just a thought!
Tread Lightly! Dave Dave Stanley Holly House Camp Lane Grimley Worcester WR26LX 01905 641529 07966528564 www.tochallengethethinking.co.uk www.pastureforlife.org > On 27 Oct 2018, at 19:49, Renaud de RICHTER <renaud.derich...@gmail.com> > wrote: > > Climate change: Low cost, low energy cooling system shows promise > https://www.bbc.com/news/science-environment-45991225 > By Matt McGrath Environment correspondent > 26 October 2018 > <image.png> > Image copyright Yang Lab / University of Colorado Boulder Image caption The > roof array that can cool a house with little energy use > Researchers in the US have scaled up a new low-cost system that could provide > efficient cooling for homes while using very little electricity. > > The team has developed a roof-top sized array, built from a highly reflective > material made from glass and polymers. > > In tests, the system kept water around 10C cooler than the ambient air when > exposed to midday sunlight in summer. > > The approach could also be scaled up to cool power stations and data centres. > > The system is based around what's termed a cooling meta-material, which is > essentially an engineered film not found in nature. > > Last year, researchers at CU Boulder in the US published research on the > extraordinary properties of the new film, which reflects back almost all > incoming light from the Sun. > > But it also has another cooling trick that makes it quite special. If you use > the film to cover water, it allows any heat in the liquid to escape into the > air. > > So when the heat escapes and is not replaced because the material deflects > away sunlight, temperatures drop rapidly. > > Now the scientists have improved the system and and built and tested a > 13-sq-metre array of panels, that's small enough to fit on most rooftops. > > "You could place these panels on the roof of a single-family home and satisfy > its cooling requirements," said Dongliang Zhao, lead author of the study from > CU Boulder's Department of Mechanical Engineering. > > How effective is this material? > > > Image copyright Glenn J. Asakawa Image caption The new material looks like > aluminium foil but is slightly thicker > The system has been tested outdoors in a variety of weather conditions. In > experiments carried out in the summer of 2017, the reflective system kept a > container of water some 12C cooler than the surrounding air in the warmest > hours of the day. > > "We can now apply these materials on building rooftops, and even build > large-scale water cooling systems with significant advantages over the > conventional air-conditioning systems, which require high amounts of > electricity to function," said Associate Professor Gang Tan, another author > of the study from the University of Wyoming. > > What makes it work? > > The key material is made with glass microspheres embedded into a polymer > film, with a thin silver coating. > > At just 50 micrometres, it is slightly thicker than aluminium foil. > > Another big advantage of the material is that it can be manufactured on > rolls, making it easier to apply on residential and commercial applications. > > What is it likely to be used for? > > > Image copyright Glenn J. Asakawa Image caption The film can be manufactured > cheaply say the authors > The authors say that one of the most effective uses of the new material would > be to cool thermoelectric power generating plants. These installations use > large amounts of water and electricity to maintain the operating temperatures > of their machinery. Using the new material could make them more efficient. > > How much cooling does the world need? > > In 2016 around 10% of the world's energy use went to power air conditioning. > The International Energy Agency says that this rate is set to triple by 2050, > with air conditioning (AC) consuming as much electricity as is used in China > today. > > As well as all the CO2 that is produced as electricity is created to power > these devices, AC units also contain potent greenhouse gases in the form of > hydrofluorocarbons. > > HFCs were introduced to protect the ozone layer, because the previous > generation of the cooling chemicals exacerbated the hole over Antarctica that > had developed in the 1980s. > > While HFCs are less damaging, they have a large global warming potential. In > 2016, countries agreed that they would be phased out over the course of the > next 15-20 years. If this happens successfully it could have a significant > impact on limiting future temperature rises. > > The new study has been published in the journal Joule. > > Dongliang Zhao ; Ablimit Aili ; Yao Zhai ; Jiatao Lu ; Dillon Kidd ; Gang Tan > ; Xiaobo Yin ; Ronggui Yang > Subambient Cooling of Water: Toward Real-World Applications of Daytime > Radiative Cooling > Published:October 26, 2018. DOI: https://doi.org/10.1016/j.joule.2018.10.006 > Highlights > > 10.6°C subambient cooling of water around noon under direct sunlight > Subambient cool-water production at various constant temperatures > The effect of weather conditions on the performance of radiative sky cooling > kW-scale radiative sky cooling system to demonstrate scalability of the > technology > Summary > > Real-world applications of radiative sky cooling require thoughtful design of > the system, along with clear understanding of weather effects on system > performance. This work explores application of radiative sky cooling based > upon a low-cost radiative cooling metamaterial that can be scalably > manufactured. A radiative cooled-cold collection (RadiCold) module is > developed to cool water to 10.6°C below ambient at noon under stationary > conditions. The effects of different weather conditions (wind speed, > precipitable water, and cloud cover) on the performance of radiative cooling > have been investigated. A kilowatt (kW)-scale RadiCold system with 13.5 m 2 > radiative cooling surface area is then built and demonstrated to provide a > maximum cooling power of 1,296 W at night, and an average cooling power of > 607 W at noon (12–2 p.m.) under 952 W/m 2 average solar irradiance at 26.5 > L/(h⋅m 2) volumetric flow rate. A building-integrated RadiCold system is > proposed to provide continuous day-and-night cooling. > <image.png> > -- > You received this message because you are subscribed to the Google Groups > "geoengineering" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to geoengineering+unsubscr...@googlegroups.com. > To post to this group, send email to geoengineering@googlegroups.com. > Visit this group at https://groups.google.com/group/geoengineering. > For more options, visit https://groups.google.com/d/optout. -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To unsubscribe from this group and stop receiving emails from it, send an email to geoengineering+unsubscr...@googlegroups.com. To post to this group, send email to geoengineering@googlegroups.com. Visit this group at https://groups.google.com/group/geoengineering. For more options, visit https://groups.google.com/d/optout.
