A new paper on the energy efficiency of buildings (here, ice hockey halls) is now published!
Energy analysis in ice hockey arenas and analytical formula for the temperature profile in the ice pad with transient boundary conditions
The energy efficiency of ice hockey arenas is a central concern for the administrations, as these buildings are well known to consume a large amount of energy. Since they are composite, complex systems, solutions to such a problem can be approached from many different areas, from managerial to technological to more strictly scientific. In this paper we consider heat transfer processes in an ice hockey hall, during operating conditions, with a bottom-up approach based upon on-site measurements. Detailed heat flux, relative humidity and temperature data for the ice pad and the indoor air are used for a heat balance calculation in the steady-state regime, which quantifies the impact of each single heat source. We also solve the heat conduction equation for the ice pad in transient regime, and obtain a general analytical formula for the temperature profile that is suitable to practical applications. When applied to the resurfacing process for validation, it shows good agreement with an analogous numerical solution. Since our formula is given with implicit initial condition and boundary conditions, it can be used not only in ice hockey halls, but in a large variety of engineering applications.
Our paper discussing the usage of geothermal energy for heating buildings is now published. You can download the full version from the publisher at the following webpage:
Our paper “A combined analytical model for increasing the accuracy of heat emission predictions in rooms heated by radiators” is now published on the Journal of Building Engineering. Here is the link to the pdf (free download for the next 50 days):
The efficiency of heat emitters plays an important role in the improvement of building energy performance, especially in the context of system and product comparison. In particular, it can be directly related to thermal comfort via the operative temperature that is effectively sensed by the users.
For the first time in the literature, in this paper we develop a combined analytical model for room and radiator that computes directly the heat output required to maintain a specific operative temperature. The total heat balance of the enclosure is used to accurately quantify and compare the heat emission losses of different radiator types via an analytical calculation of the operative temperature. This determines the efficiency of a selection of panel radiators with different surface temperature, radiation fraction and number of panels, which were tested in a chamber conforming to the EN 442-2 standard.
Additionally, we assess the related annual energy consumption in different climates by carrying out annual simulations in old (without heat recovery) and new (with heat recovery) building types located in Tallinn, Estonia and Strasbourg, France. In the new building we find a similar performance for all the radiators. In the old building however, one radiator outperforms the other two with up to 1.38% lower annual energy consumption, due to smaller rear losses and higher thermal comfort provided by the larger front panel surface.
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:
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.
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:
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:
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.