New paper on energy engineering published today

Cheers!

I have just published a new article entitled “Optimization of Radiators, Underfloor and Ceiling Heater Towards the Definition of a Reference Ideal Heater for Energy Efficient Buildings”. We discuss analytical methods for optimization of heating systems in residential buildings, providing a formal efficiency analysis and some specific optimal configurations.
Here I am using a simple analytical method that I have developed some time ago for a different topic (predicting hot water consumption in residential buildings).
You can view the article (with open access) and download it for free at the following address:
https://www.mdpi.com/2076-3417/8/12/2477

Abstract:
Heat emitters, as the primary devices used in space heating, cover a fundamental role in the energy efficient use of buildings. In the search for an optimized design, heating devices should be compared with a benchmark emitter with maximum heat emission efficiency. However, such an ideal heater still needs to be defined. In this paper we perform an analysis of heat transfer in a European reference room, considering surface effects of thermal radiation and computing the induced operative temperature (op.t.) both analytically and numerically. Our ideal heater is the one determining the highest op.t. By means of functional optimization, we analyse trends such as the variation of operative temperature with radiator panel dimensions, finding optimal configurations. To make our definitions as general as possible, we address panel radiators, convectors, underfloor (UFH) and ceiling heater. We obtain analytical formulas for the operative temperature induced by panel radiators and identify the 10-type as our ideal radiator, while the UFH provides the best performance overall. Regarding specifically UFH and ceiling heaters, we find optimal sizes providing maximum op.t. The analytical method and qualitative results reported in this paper can be generalized and adopted in most studies concerning the efficiency of different heat emitter types in building enclosures.

Philosophy paper “Epistemological Explanation of Lean Construction” now published

Cheers!

You might already know that I’m very fond of philosophy. I loved it immediately, as soon as I started my studies in high school in Italy, back in the 90s. I certainly refer to it in my daily life, more or less explicitly; after all, my entire Quantum Prana concept is based on the interaction between Eastern and Western traditions.

Interestingly enough though, sometimes it happens that you don’t see a tangible outcome of your studies for a long period of time. Perhaps, even for over two decades.
And in fact, here it is! A paper entitled “Epistemological Explanation of Lean Construction” that I wrote together with my colleagues at Aalto University, Finland and at the University of Huddersfield, UK.

My contribution consists of a short review and comparison of the classical epistemology of Plato and Aristotle. I then explain how their differences got enhanced through the centuries, until the debate between the Rationalists (René Descartes, Baruch Spinoza, and Gottfried Wilhelm Leibniz) and the British Empiricists (John Locke, George Berkeley, and David Hume), commenting also on their role in cosmology.

I then move forward by shortly analyzing some features of the epistemology of Edmund Husserl and Martin Heidegger, in relation with tacit knowledge and Japanese philosophy.

At this webpage you can read our paper for free or download it in PDF:

https://ascelibrary.org/doi/10.1061/%28ASCE%29CO.1943-7862.0001597

Theoretical physics paper now published

My article on reheating and gravitino production in MSSM inflation is now published in The European Physical Journal C. It is a full access publication, if you are interested you can find it here:

https://link.springer.com/article/10.1140/epjc/s10052-017-5269-8

Abstract

In the framework of MSSM inflation, matter and gravitino production are here investigated through the decay of the fields which are coupled to the udd inflaton, a gauge-invariant combination of squarks. After the end of inflation, the flat direction oscillates about the minimum of its potential, losing at each oscillation about 56% of its energy into bursts of gauge/gaugino and scalar quanta when crossing the origin. These particles then acquire a large inflaton VEV-induced mass and decay perturbatively into the MSSM quanta and gravitinos, transferring the inflaton energy very efficiently via instant preheating. Regarding thermalization, we show that the MSSM degrees of freedom thermalize very quickly, yet not immediately by virtue of the large vacuum expectation value of the inflaton, which breaks the SU(3)C×U(1)YSU(3)C×U(1)Y symmetry into a residual U(1). The energy transfer to the MSSM quanta is very efficient, since full thermalization is achieved after only O(40)O(40) complete oscillations. The udd inflaton thus provides an extremely efficient reheating of the Universe, with a temperature Treh=O(108GeV)Treh=O(108GeV), which allows for instance several mechanisms of baryogenesis. We also compute the gravitino number density from the perturbative decay of the flat direction and of the SUSY multiplet. We find that the gravitinos are produced in negligible amount and satisfy cosmological bounds such as the Big Bang nucleosynthesis (BBN) and dark matter (DM) constraints.

My new article on materials science

Here is my newest paper!

“Thermomechanical generation of fissure patterns on the surface of heated circular wood samples”

https://arxiv.org/abs/1709.03546

We discuss the observation of primary crack patterns on the surface of heated medium density fiberboard (MDF) round samples in inert atmosphere. A constant heat flux irradiates the wood surface, and the primary cracks seem to appear instantaneously at a temperature below the pyrolysis point, \textit{before} any actual charring. Such fissures were originally believed to form mainly by the action of physicochemical processes; on the contrary, we show here that below the pyrolysis temperatures this occurs by means of thermomechanical surface instability. The crack patterns can indeed be explained qualitatively by the simultaneous thermal expansion and softening of the hot surface layer, which is restrained by the colder wood beneath. This generates membrane compressive stresses leading to surface instability. Physically, this is a consequence of the thermomechanical properties of wood, which is a natural thermoplastic. In this paper, the macro-crack topology is reproduced by a full 3D thermomechanical instability model. We obtain the patterns by solving the according eigenvalue problem numerically, by Finite Element Method (FEM). We also formulate the model in 2D, assuming a circular soft thin plate bonded to an elastic foundation, and solve it both analytically and numerically. Finally, we compare our results with analogous crack patterns appearing on the surface of square samples, which we discussed in a previous study. We conclude that very different pattern symmetries (orthotropic, isotropic and circular) might be explained by the same model of thermomechanical surface instability.

Slides for my talk on analytical modelling of energy consumption

Domestic Hot Water (DHW) is an important source of energy consumption for any type of building. I attach here the slides of a short (20 mins) talk I gave on this topic yesterday, at the Energy7 conference in Manchester UK:

Analytical modelling and prediction formulas for domestic hot water consumption – slides

I briefly outline an analytical bottom-up method to model DHW consumption accurately. We

 1) derive the correlations between occupant groups and different seasons => MAIN TREND OF CONSUMPTION
 2) generate a PREDICTIVE FORMULA for the DHW consumption of unknown occupant groups.

The slides are in PDF format (just use the pgup/pgdn keys on your keyboard to scroll). The talk is based on a paper I published last Spring, described in this entry of my blog.

Greetings from Manchester!

ON EPISTEMOLOGY OF CONSTRUCTION ENGINEERING AND MANAGEMENT

Here is the short version (conference proceedings) of our epistemology paper, discussing how Plato’s and Aristotle’s methodologies affected engineering practice, research and education during the last two centuries.

Click to access iglc-f15a7a9d-3917-4eed-ac33-1549c1719305.pdf



As a polemical side note, this shows that, contrary to some well-established pedagogical practice, you should not study at school only what you’ll need for your day job (call it Anglo-saxon, or Nordic Pragmatism).
Let me thus praise my high school formation in Italy, where three years of demanding *compulsory* philosophical studies allowed me, 20 years later, to write this paper ).

 

Lyrics of 男儿当自强 (A Man Should Strengthen Himself)

Wonderful and deep lyrics from a Chinese folk song.

The Hesitant Prize Fighter

This is a song I guess many Chinese may have heard it in their life. Well. I notice it is found in many Kungfu Movies and even my Chinese friends who cannot converse in mandarin knows this song…

Actually I found many transalation of the title, They are “A Man Of Determination” , “A Man Should Better Himself”. t personnally I think the word 自强 should mean “To Strive To Stengthen Oneself” which I think is a more accurate translation of that.

In a time of crisis now, I guess its time for everyone to strive to become stronger, so I decided to try translating the meaning of the song to english so that everyone can understand what he is trying to say.

It is interesting to know that the tune of the song actually came from a chinese folk song called The General’s Mandate” 將軍令. It was also known to…

View original post 504 more words

First material science paper now published

My paper on thermomechanical processes of charring wood is now published in Combustion And Flame. Here you can download the pdf for free for 50 days, if you are interested 🙂

In our study we develop a model for explaining the crack patterns which are formed on the wood surface when this is exposed to intense heat. It was believed for decades that such cracks are created by physicochemical processes like shrinkage, with impossibility to obtain an analytical model predicting their topology. On the contrary, we show that if one assumes the origin to be thermomechanical, the according analytical model can produce formulas which can describe and predict the crack patterns with an excellent agreement with the observations.

Here is the abstract:


In the assessment of wood charring, it was believed for a long time that physicochemical processes were responsible for the creation of cracking patterns on the charring wood surface. This implied no possibility to rigorously explain the crack topology. In this paper we show instead that below the pyrolysis temperatures, a primary global macro-crack pattern is already completely established by means of a thermomechanical instability phenomenon. First we report experimental observations of the crack patterns on orthotropic (wood) and isotropic (Medium Density Fibreboard) materials in inert atmosphere. Then we solve the 3D thermomechanical buckling problem numerically by using the Finite Element Method, and show that the different crack topologies can be explained qualitatively by the simultaneous thermal expansion and softening, taking into account the directional dependence of the elastic properties. Finally, we formulate a 2D model for a soft layer bonded to an elastic substrate, and find an equation predicting the inter-crack distance in the main crack-pattern for the orthotropic case. We also derive a formula for the critical thermal stress above which the plane surface will wrinkle and buckle. The results can be used for finding new ways to prevent or delay the crack formation, leading to improved fire safety of wood-based products.


I am now working with my colleagues on some developments of the model.

Thermal greetings to everybody!
Andrea /QP

First paper on energy efficiency published

Greetings!

My paper on theoretical modelling of daily hot water consumption in residential buildings is now published in Energy And Buildings. Here follows the abstract:

We consider Domestic Hot Water (DHW) consumption hourly data for Finnish apartments in November and August. Using datasets obtained in a previous work, we formulate a bottom-up model to quantify correlations in the consumption patterns, which are discerned by a different number of occupants for both weekday (WD) and weekend (WE). The analytical formulas thus obtained describe accurately the hourly consumption of any specific dataset. In particular, we can generate the consumption curves for unknown datasets and derive quantitatively the correlations between occupant groups and different seasons. We explain this procedure into details, define the key variables of the model and validate it against the measurements. Our quantitative results are immediately applicable to simulation tools for energy investigations and sizing of heating systems in Finland or areas with similar occupant behavior. More generally, the analytical, inductive method here introduced could be adapted to DHW studies concerning other geographic areas as well. We also argue that this simple, yet effective formalism might also be extended to other engineering contexts that are not strictly related to energy consumption. For example, the main idea could be developed and adapted to those disciplines where understanding dataset correlations constitutes an important investigation tool.


Analytical modelling and prediction formulas for domestic hot water consumption in residential Finnish apartments. Available from: https://www.researchgate.net/publication/309672534_Analytical_modelling_and_prediction_formulas_for_domestic_hot_water_consumption_in_residential_Finnish_apartments.

I will present these results in August, at the 7th International Symposium on Energy in Manchester: http://energy7.nscj.co.uk/

Energetic cheers!
Andrea /QP