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Heat Transfer

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Chementator: A sound way to reuse low-temperature waste heat

In a so-called thermoacoustic engine, researchers from the Energy Research Center of the Netherlands (ECN; Petten, Netherlands; www.ecn.nl) have achieved a record efficiency in the conversion of heat to sound, improving the existing record of 41% to 48% of the…

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A primer on coal-to-liquids

As an energy resource, global coal reserves represent 2,000 billion barrels of oil equivalent. In 2007, global oil reserves were about 1,300 billion barrels of oil. World wide, oil demand will grow 40 to 50% by 2030. But coal offers…

Chementator: Pretreatment helps recover more coal from primary flotation step

Coal is typically cleaned by gravity separation to reduce ash and pyrite content, with flotation used to recover fines. Various methods have been applied to disperse fine clay particles from the surface of coal particles and thus improve coal flotation…

Chementator: This LNG vaporization process will reduce air emissions

A new method for vaporizing liquefied natural gas (LNG) that is more environmentally friendly than the traditional submerged combustion vaporization (SCV) process is being offered by Black & Veatch (B&V; Overland Park, Kan.; www.bv.com). In an SCV process, LNG is…

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Engineering Practice: Estimating Thermal Conductivity of Hydrocarbons

The thermal conductivity of hydrocarbons is an essential parameter that needs to be known when designing heat transfer equipment. Presented here is a simple-to-use correlation that was developed for predicting thermal conductivities of liquid paraffin hydrocarbons, petroleum fractions and atmospheric…

Chementator: Ceramic heat exchangers offer more than corrosion resistance

ESK Ceramics GmbH & Co. KG (Kempten, www.esk.com), together with Pfaudler Werke GmbH (Schwetzingen, both Germany; www.pfaudler.de), has launched a new plate heat exchanger made of silicon carbide. ESK is producing the ceramic heat exchangers on a large scale for…

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Cover Story Part 1: Heat Flux And Film Temperature In Fired, Thermal-Fluid Heaters

In a fired thermal fluid heater, a thermal fluid is heated by the metal surfaces of a fired heater or fluegas heat-recovery exchanger. Generally, the heat input rate is controlled to achieve some desired bulk-fluid temperature exiting the heater. However,…

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Heat Transfer Fluids: Maintaining the System

Organic-based thermal fluids provide relatively trouble-free service for significant periods of time. However, there comes a time when any fluid (either aromatic- or aliphatic-based) needs to be replaced. Since aromatic-based fluids generally cost more and are complicated to dispose of,…

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Engineering Practice: Get More From Vertical Thermosiphon Reboilers

A very common heat exchanger in the chemical process industries (CPI) is the vertical thermosiphon reboiler (VTR; Figure 1). Due to size and fluid-flow restrictions, however, its heat transfer rate is often quite low. The subcooled region formed at the…

October 2008: Letters, announcements, postscripts and corrections

Webinar: Heat Transfer Optimum Performance in Thermal Fluid Heating Systems: The importance of heat flux and film temperature Date: November 6, 2008 | Time: 11am EST In circulating thermal-fluid heating systems, the rate of heat transfer is typically controlled to…