design

Georgian interior design and efficient radiators

My lecture last week, to first year students studying thermodynamics, was about energy flows and, in particular, heat transfer.  I mentioned that, despite being called radiators, radiation from a typical central heating radiator represents less than a quarter of its heat output with rest arising from convection [see post entitled ‘On the beach‘ on July 24th, 2013 for an explanation of types of heat transfer].  This led one student to ask whether black radiators, with an emissivity of close to one, would be more efficient.  The question arises because the rate of radiative heat transfer is proportionate to the difference in the fourth power of the temperature of the radiator and its surroundings, and to the surface emissivity of the surface of the radiator.  This implies that heat will transfer more quickly from a hot radiator but also more slowly from a white radiator that has an emissivity of 0.05 compared to 1 for black surface.

Thus, a black radiator will radiator heat more quickly than a white one; but does that mean it’s more efficient?  The first law of thermodynamics demands that the nett energy input to a radiator is the same as the energy input required to raise the temperature of the space in which it is located.  Hence, the usual thermodynamic definition of efficiency, i.e. what we want divided by what we must supply, does not apply.  Instead, we usually mean the rate at which a radiator warms up a room or the size of the radiator required to heat the room.  In other words, a radiator that warms a room quickly is considered more efficient and a small radiator that achieves the same as large one is also considered efficient.  So, on this basis a black radiator will be more efficient.

Recent research by a team, at my alma mater, has shown that a rough black wall behind the radiator also increases its efficiency, especially when the radiator is located slightly away from the wall.  Perhaps, it is time for interior designers to develop a retro-Georgian look with dark walls, perhaps with sand mixed into the paint to increase surface roughness.

Sources:

Beck SMB, Grinsted SC, Blakey SG & Worden K, A novel design for panel radiators, Applied Thermal Engineering, 24:1291-1300, 2004.

Shati AKA, Blakey SG & Beck SBM, The effect of surface roughness and emissivity on radiator output, Energy and Buildings, 43:400-406, 2011.

Image details:

Verplank 2 002<br />
Working Title/Artist: Woodwork of a Room from the Colden HouseDepartment: Am. Decorative ArtsCulture/Period/Location: HB/TOA Date Code: Working Date: 1767<br />
Digital Photo File Name: DP210660.tif<br />
Online Publications Edited By Steven Paneccasio for TOAH 1/3/14

https://www.metmuseum.org/toah/works-of-art/40.127/

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Airborne urban mobility

Pop.Up_copyright Italdesign 2

At the Airbus PhD workshop that I attended a couple of weeks ago [see my post entitled Making Engineering Work for Society on September 13th 2017], Axel Flaig, Head of Airbus Research and Technology, gave us an excellent opening presentation describing their vision for the future.  Besides their vision for the next generation of passenger aircraft with reductions in CO2, NOx and noise emissions of 75%, 90% and 65% respectively against 2000 levels by 2050, they are also looking at urban air mobility.  We have 55 megacities [cities with a population of more than 10 million] and it is expected that this will increase to 93 by 2035 [see my post entitled ‘Hurrying Feet in Crowded Camps’ on August 16th, 2017].  These megacities are characterized by congestion and time-wasted moving around them; so, Airbus is working on designs for intra-city transport that takes us off the roads and into the air.  Perhaps the most exciting is the electric Pop.up concept that is being developed with Italdesign.  But, Airbus are beyond concepts: they have a demonstrator single-seater, self-pilot vehicle, the Vahana that will fly in 2017 and a multi-passenger demonstrator scheduled to fly in 2018.

Soon, we will have to look left, right and up before we cross the road, or maybe nobody will walk anywhere – though that would be bad news for creative thinking [see my post on ‘Gone Walking’ on 19th April 2017], amongst other things!

 

Image from http://www.airbus.com/newsroom/press-releases/en/2017/03/ITALDESIGN-AND-AIRBUS-UNVEIL-POPUP.html where there is also a video.

Making engineering work for society

Last week I attended a one-day workshop for PhD students sponsored by Airbus.  Most of the students produced a poster describing their research; and a dozen brave ones gave a three-minute presentation on their PhD thesis.  It’s a challenge to describe three years of research in three minutes to an audience that are not experts in your specialist field.  However, the result was an exciting and stimulating morning covering subjects as diverse as multidisciplinary design optimization and cognitive sources of ethical behaviour in business.  The latter was presented by Solenne Avet who was the only woman amongst the twelve three-minute thesis presenters.  The gender diversity was better for the other, longer talks with two women out of six presenters.  Interestingly, the female PhD students were the only ones tackling the interaction between engineering and human behaviour, including system-human communication, collective engineering work and innovation processes, which I have suggested is essential for viable engineering solutions to our global and societal challenges [see my post ‘Re-engineering engineering’ on August 30th, 2017].  This population sample is too small to make a reliable generalization; however, it suggests that a gender-balanced engineering profession would be more likely to succeed in making substantial contributions to our current challenges [see UN Global Issues Overview].

Image from https://members.architecture.com/custom/bespoke/directory/view_images.asp?id=257460&type=O&dir=1&CaseRef=140776&imgName=43535_100017586_1.jpg

Re-engineering engineering

More than a decade ago, when I was a Department Head for Mechanical Engineering, people used to ask me ‘What is Mechanical Engineering?’.  My answer was that mechanical engineering is about utilising the material and energy resources available in nature to deliver goods and services demanded by society – that’s a broad definition.  And, mechanical engineering is perhaps the broadest engineering discipline, which has enable mechanical engineers to find employment in a wide spectrum areas from aerospace, through agricultural, automotive and biomedical to nuclear and solar energy engineering.  Many of these areas of engineering have become very specialised with their proponents believing that they have a unique set of constraints which demand the development of special techniques and accompanying language or terminology.  In some ways, these specialisms are like the historic guilds in Europe that jealously guarded their knowledge and skills; indeed there are more than 30 licensed engineering institutions in the UK.

In an age where information is readily available [see my post entitled ‘Wanted: user experience designers‘ on July 5th, 2017], the role of engineers is changing and they ‘are integrators who pull ideas together from multiple streams of knowledge’ [to quote Jim Plummer, former Dean of Engineering at Stanford University in ‘Think like an engineer‘ by Guru Madhaven].  This implies that engineers need to be able work with a wide spectrum of knowledge rather than being embedded in a single specialism; and, since many of the challenges facing our global society involve complex systems combining engineering, environmental and societal components, engineering education needs to include gaining an understanding of ecosystems and the subtleties of human behaviour as well as the fundamentals of engineering.  If we can shift our engineering degrees away from specialisms towards this type of systems thinking then engineering is likely to enormously boost its contribution to our society and at the same time the increased relevance of the degree programmes might attract a more diverse student population which will promote a better fit of engineering solutions to the needs of our whole of global society [see also ‘Where science meets society‘ on September 2nd 2015).

For information on the licensed engineering institutions in the UK see: https://www.engc.org.uk/about-us/our-partners/professional-engineering-institutions/

Getting smarter

A350 XWB passes Maximum Wing Bending test [from: http://www.airbus.com/galleries/photo-gallery%5D

Garbage in, garbage out (GIGO) is a perennial problem in computational simulations of engineering structures.  If the description of the geometry of the structure, the material behaviour, the loading conditions or the boundary conditions are incorrect (garbage in), then the simulation generates predictions that are wrong (garbage out), or least an unreliable representation of reality.  It is not easy to describe precisely the geometry, material, loading and environment of a complex structure, such as an aircraft or a powerstation; because, the complete description is either unavailable or too complicated.  Hence, modellers make assumptions about the unknown information and, or to simplify the description.  This means the predictions from the simulation have to be tested against reality in order to establish confidence in them – a process known as model validation [see my post entitled ‘Model validation‘ on September 18th, 2012].

It is good practice to design experiments specifically to generate data for model validation but it is expensive, especially when your structure is a huge passenger aircraft.  So naturally, you would like to extract as much information from each experiment as possible and to perform as few experiments as possible, whilst both ensuring predictions are reliable and providing confidence in them.  In other words, you have to be very smart about designing and conducting the experiments as well as performing the validation process.

Together with researchers at Empa in Zurich, the Industrial Systems Institute of the Athena Research Centre in Athens and Dantec Dynamics in Ulm, I am embarking on a new EU Horizon 2020 project to try and make us smarter about experiments and validation.  The project, known as MOTIVATE [Matrix Optimization for Testing by Interaction of Virtual and Test Environments (Grant Nr. 754660)], is funded through the Clean Sky 2 Joint Undertaking with Airbus acting as our topic manager to guide us towards an outcome that will be applicable in industry.  We held our kick-off meeting in Liverpool last week, which is why it is uppermost in my mind at the moment.  We have 36-months to get smarter on an industrial scale and demonstrate it in a full-scale test on an aircraft structure.  So, some sleepness nights ahead…

Bibliography:

ASME V&V 10-2006, Guide for verification & validation in computational solid mechanics, American Society of Mech. Engineers, New York, 2006.

European Committee for Standardisation (CEN), Validation of computational solid mechanics models, CEN Workshop Agreement, CWA 16799:2014 E.

Hack E & Lampeas G (Guest Editors) & Patterson EA (Editor), Special issue on advances in validation of computational mechanics models, J. Strain Analysis, 51 (1), 2016.

http://www.engineeringvalidation.org/