Apr 12, 2009
Heat exchangers sit at the core of every petrochemical facility, and represent a market segment projected to cross US$12.7 billion by 2012. Petrochemicals Middle East investigates the systems available, and how to find the model best suited to your budget.
Heat exchangers are devices specifically designed for the efficient transfer of heat from one fluid to another over a solid surface. This transfer of heat can either take the form of absorption or dissipation of heat. Heat exchangers can be found in everyday equipment from boilers, furnaces, refrigerators to air conditioning systems.
The exchangers used transfer heat from one liquid to another, without allowing them to mix. The exchange can be to alter the temperature, or state of liquids, either condensing or boiling as required.
Regardless of the function the heat exchanger fulfills, in order to transfer heat the fluids involved must be at different temperatures and they must come into thermal contact, as heat can flow only from the hot to cold, thus the heat is transferred via a metal plate isolating the two fluids.
Heat exchangers are found in most chemical, electrical or mechanical systems and they serve as the system’s means of gaining or rejecting heat. Some of the more common applications are found in heating, electronic equipment, ventilation and air conditioning (HVAC) systems, radiators or internal combustion engines, boilers, condensers and gas preheaters.
April 21, 2009
"The boundary inverse heat conduction problem (BIHCP) deals with the determination of the surface heat flux or the surface temperature from measured transient temperatures inside a conducting body where the initial temperature is known. This work addresses a BIHCP related to the spatiotemporal heat conduction in a large slab when a time-variable heat flux is prescribed at an exposed surface and the other surface is thermally insulated," investigators in the United States report.
"Two different heating waveforms are studied: a constant heat flux and a time-dependent triangular heat flux. The numerical temperature-time history at the insulated surface of the large slab provides the ''temperature-time measurement'' with one temperature sensor. Framed in the theory of the method of lines (MOL) first and employing rudimentary concepts of numerical differentiation later, the main objective of this paper is to develop a simple computational methodology to estimate the temporal evolution of temperature at the exposed surface of the large slab receiving the two distinct heat fluxes," wrote A. Campo and colleagues, University of Vermont.
The researchers concluded: "In the end, it is confirmed that excellent predictions of the surface temperatures versus time are achievable for the two cases tested while employing the smallest possible system of two heat conduction differential equations of first-order."
Campo and colleagues published their study in the Journal of Heat Transfer - Transactions of the ASME (Effortless Application of the Method of Lines for the Inverse Estimation of Temperatures in a Large Slab With Two Different Surface Heating Waveforms. Journal of Heat Transfer - Transactions of the ASME, 2009;131(2):24501).
For additional information, contact A. Campo, University of Vermont, Dept. of Mech Engineering, 33 Colchester Avenue, Burlington, VT 05405, USA.
The publisher of the Journal of Heat Transfer - Transactions of the ASME can be contacted at: ASME-American Society Mechanical Eng, Three Park Avenue, New York, NY 10016-5990, USA.
Sources from: http://www.controleng.com/articleXml/LN956740633.html
25th April 2009
A rusting, 130-year-old loco steam boiler rescued from under layers of dust at Malta Shipyards has become a popular attraction outside the Maritime Museum at the Vittoriosa Waterfront. It has also drawn the attention of historians of British industry since no similar example exists in the UK.
The loco boiler was one of three recovered from the shipyard and is being restored under the supervision of Heritage Malta.
It was a loco boiler such as this which powered the first football match ever held under floodlights. Coincidentally, the match involved Sheffield United, now under sponsorship by the Malta Tourism Authority.
Sources from: http://www.timesofmalta.com/articles/view/20090425/local/antique-steam-boil-becomes-attraction