All considerations for thermal design should consider the four principle facets of thermal design.

Four principle facets of thermal design 1. Heat transfer analysis

2. Materials performance 3. Heating & cooling technology 4. Instrumentation & control

If important considerations are met, then the majority of thermal design problems do not occur. A review of the following few thermal design considerations, before or after a thermal design effort is encouraged. * Thermal specifications should be realistic. Thermal design specifications must be realistic, necessary, and achievable. If unrealistic specifications are established, then they should be probed to arrive at realistic specifications. * Physical property variations with temperature. The thermal conductivity and thermal expansion (linear, area, volumetric) of the materials should be considered.

Due to varying temperature, the physical properties may change. The viscosity of water and many other liquids is sensitive to temperature changes as is the effective thermal conductivity of insulation. During operating transients, thermal expansion effects have to be taken note of to avoid mechanical distortion and failure. * Physical property variations with age. Due to aging or performing at higher temperatures, many materials witness loss of mechanical strength and changes in surface properties. * Materials should be compatible.

At a given temperature, many materials may be compatible that may prove to be chemically incompatible at another temperature. * Limits of temperature. The temperature limits of all materials should be considered and should be adequate. * The properties of materials should be evaluated. Sometimes the actual physical properties of materials may differ from the values given in the handbook. Thus, design margins should be included or measurement of the properties of the materials should be considered to ensure desired performance. * Heat gains or losses from supporting systems or components. The heat balance may be dominated by such parasitic heat losses or gains. Thermal "shorts" or transferring heat via piping systems may be considered. * Application of the first law of thermodynamics. To maintain overall thermal balance, a control volume should be considered and defined.

* Ultimate heat sink/source. The capacity should be considered to evaluate whether over time, due to thermal load, the temperature of the heat sink/source will change or not. * Heat effects due to chemical reactions. Thermal requirements may be significantly affected due to small amounts of water being evaporated or condensed. * Heat generated due to structure or friction. Instrument and power measurement circuits generate heat and the effects of such heat gains should be considered. Compressors, bearings, fans contribute towards heat gain. * Startup and shutdown. To achieve the required startup and shutdown times, whether heating or cooling, the rate of thermal energy exchange may exceed the normal operating requirements. Sizing the thermal power supply accordingly should be considered. * Radiation, conduction, convection. The three modes of heat transfer should be considered. At near ambient temperatures, radiation should be considered. Techniques for efficient and improved convective heat transfers as well as two-dimensional conduction effects also deserve consideration. * Surface fouling. This is a potential problem of degrading heat-transfer performance due to corrosion, deposition, or precipitation. * Oversized systems. If the load is less or in part-load situations, will the oversized system provide efficient control? * Susceptibility to environmental changes. Internal and external surfaces that are exposed to air should be considered at operating temperatures below ambient for effects of humidity, sunlight, condensation, and frost. * Safety. Operator and equipment safety should be considered in the event of the failure of the thermal control system along with the burn potential of surfaces. References: Eric C. Guyer, David L. Brownell, "Handbook of Applied Thermal Design", pages 18-19, published by Taylor & Francis, 1999, ISBN 1560328118, 9781560328117. -o- Author: Rajen Jani Rajen Jani is a professional freelance writer with 18+ years of experience. http://rajenjani.wordpress.com/ http://www.rajenjani.com/ Article Source: http://EzineArticles.com/?expert=Rajen_Jani CalFinder Remodeling Blog CalFinder Q&A: Determining LEED Points … CalFinder Blog: CalFinder Q&A: Determining LEED Points for Solar Thermal Systems. Applying thermal compound best & easiest way ? – Overclock.net … I will be installing my hyper 212 tomorrow and have never applied any compound always used stock HSF. Iv’e been reading and so far its been suggested. Solar thermal plant eyed for Nevada | Cooler Planet News New solar energy resources may soon be developed in Nevada, including a 250-megawatt facility in Nye County. Tyco Thermal Controls Heat Tracing Snow Melting De Icing News 050309 Building design news Tyco Thermal Controls Heat Tracing Snow Melting De Icing Specialty Heating Floor Heating Cooling Temperature Measurement Leak Detection Fire and Perfomance Wiring 050309.

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The pioneering work on polyurethane polymers was conducted by Otto Bayer and his coworkers in 1937 at the laboratories of I.G. Farben in Leverkusen, Germany. They recognized that using the polyaddition principle to produce polyurethanes from liquid diisocyanates and liquid polyether or polyester diols seemed to point to special opportunities, especially when compared to already existing plastics that were madeby polymerizing olefins, or by polycondensation.

The new monomer combination also circumvented existing patents obtained by Wallace Carothers on polyesters.

Initially, work focused on the production of fibres and flexible foams.

With development constrained by World War II (when PU’s were applied on a limited scale as aircraft coating), it was not until 1952 that polyisocyanates became commercially available. Commercial production of flexible polyurethane foam began in 1954, based on toluene diisocyanate (TDI) and polyester polyols. The invention of these foams (initially called imitation swiss cheese by the inventors) was thanks to water accidentally introduced in the reaction mix. These materials were also used to produce rigid foams, gum rubber, and elastomers. Linear fibres were produced from hexamethylene diisocyanate (HDI) and 1,4-butanediol (BDO). The first commercially available polyether polyol, poly(tetramethylene ether) glycol), was introduced by DuPont in 1956 by polymerizing tetrahydrofuran. Less expensive polyalkylene glycols were introduced by BASF and Dow Chemical the following year, 1957. These polyether polyols offered technical and commercial advantages such as low cost, ease of handling, and better hydrolytic stability; and quickly supplanted polyester polyols in the manufacture of polyurethane goods. Another early pioneer in PU’s was the Mobay corporation. In 1960 more than 45,000 tons of flexible polyurethane foams were produced. As the decade progressed, the availability of chlorofluoroalkane blowing agents, inexpensive polyether polyols, and methylene diphenyl diisocyanate (MDI) heralded the development and use of polyurethane rigid foams as high performance insulation materials.Rigid foams based on polymeric MDI (PMDI) offered better thermal stability and combustion characteristics than those based on TDI. In 1967, urethane modified polyisocyanurate rigid foams were introduced, offering even better thermal stability and flammability resistance to low density insulation products.

Also during the 1960s, automotive interior safety components such as instrument and door panels were produced by back-filling thermoplastic skins with semi-rigid foam. In 1969, Bayer AG exhibited an all plastic car in Dusseldorf, Germany. Parts of this car were manufactured using a new process called RIM, Reaction Injection Molding. RIM technology uses high-pressure impingement of liquid components followed by the rapid flow of the reaction mixture into a mold cavity. Large parts, such as automotive fascia and body panels, can be molded in this manner.

Polyurethane RIM evolved into a number of different products and processes. Using diamine chain extenders and trimerization technology gave poly(urethane urea), poly(urethane isocyanurate), and polyurea RIM. The addition of fillers, such as milled glass, mica, and processed mineral fibres gave arise to RRIM, reinforced RIM, which provided improvements in flexural modulus (stiffness) and thermal stability. This technology allowed production of the first plastic-body automobile in the United Sates, the Pontiac Fiero, in 1983. Further improvements in flexural modulus were obtained by incorporating preplaced glass mats into the RIM mold cavity, also known as SRIM, or structural RIM. Starting in the early 1980s, water-blown microcellular flexible foam was used to mold gaskets for panel and radial seal air filters in the automotive industry. Since then, increasing energy prices and the desire to eliminate PVC plastisol from automotive applications have greatly increased market share. Costlier raw materials are offset by a significant decrease in part weight and in some cases, the elimination of metal end caps and filter housings.

Highly filled polyurethane elastomers, and more recently unfilled polyurethane foams are now used in high-temperature oil filter applications. Polyurethane foam (including foam rubber) is often made by adding small amounts of volatile materials, so-called blowing agents, to the reaction mixture. These simple volatile chemicals yield important performance characteristics, primarily thermal insulation. In the early 1990s, because of their impact on ozone depletion, the Montreal Protocol led to the greatly reduced use of many chlorine-containing blowing agents, such as trichlorofluoromethane (CFC-11). Other haloalkanes, such as the

hydrochlorofluorocarbon 1,1-dichloro-1-fluoroethane (HCFC-141b), were used as interim replacements until their phase out under the IPPC directive on greenhouse gases in 1994 and by the Volatile Organic Compounds (VOC) directive of the EU in 1997 (See: Haloalkanes). By the late 1990s, the use of blowing agents such as carbon dioxide, pentane, 1,1,1,2-tetrafluoroethane (HFC-134a) and 1,1,1,3,3-pentafluoropropane (HFC-245fa) became more widespread in North America and the EU, although chlorinated blowing agents remained in use in many developing countries. Building on existing polyurethane spray coating technology and polyetheramine chemistry, extensive development of two-component polyurea spray elastomers took place in the 1990s. Their fast reactivity and relative insensitivity to moisture make them useful coatings for large surface area projects, such as secondary containment, manhole and tunnel coatings, and tank liners. Excellent adhesion to concrete and steel is obtained with the proper primer and surface treatment.

During the same period, new two-component polyurethane and hybrid polyurethane-polyurea elastomer technology was used to enter the marketplace of spray-in-place load bed liners. This technique for coating pickup truck beds and other cargo bays creates a durable, abrasion resistant composite with the metal substrate, and eliminates corrosion and brittleness associated with drop-in thermoplastic bed liners. The use of polyols derived from vegetable oils to make polyurethane products began garnishing attention beginning around 2004, partly due to the rising costs of petrochemical feedstocks and partially due to an enhanced public desire for environmentally friendly green products. One of the most vocal supporters of these polyurethanes made using natural oil polyols is the Ford Motor Company. Author: Waheed Hassan Gyproc adds power to vacuum sanding The Gyproc Power Sander Vacuum from the Gyproc Professional Tools range by Artex is designed for use with the company’s Power… Read more… London Builders Blackthorne – BladeRunner from Gyproc Tools Tool Recommendation | Fast Way to Cut Plasterboard Safley. BladeRunner from Gyproc Tools – Reduce the risk of accidents. Cutting time halved; Cuts shapes, corners and circles; neat professional finish. 30 minute-rated insulated roof lining … insulated dry internal lining, and can be jointed and decorated in the normal way to give smooth monolithic appearance. It is available to order from leading builders merchants and stock. Where can I find a wide selection of metal framing dry lining … British Gypsum web site will give you answers to not only the framing but the sheeting also. They should also be able to give you suppliers in your area. thierrysmum says:. March 5, 2009 at 8: Falling demand forces job cuts at British Gypsum – Building Materials producer says economic downturn means it must scale down production.

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One of the easiest and most cost-effective ways to save on heating costs is actually to insulate your attic.

 media these days about new energy-efficient furnaces,

but if you’re not planning on replacing your heating system any time soon, or simply can’t afford the big price tag on some of these eco-friendly appliances, insulation is relatively inexpensive and highly effective.

As everyone knows, hot air rises. So, if your attic is not properly insulated, the warm air in your home just keeps rising-right on out the roof! Adding insulation to your attic keeps that air from leaking out and actually reduces the amount of time your furnace has to run to maintain the temperature in your home. There are a number of different types of attic insulation available today, but here are three of the most common varieties. Fiberglass Batt Insulation Fiberglass batts are what most people think of when they hear the word "insulation": these are the long pink or yellow strips used in most modern houses. Batt insulation is simple to install and comes in an assortment of R-values.

It is available with or without vapor barrier backings. Many homeowners like the ease of installation, although fiberglass batt insulation is ideal for spaces without lots of wires, pipes, or other protrusions as slits/holes need to be cut to accommodate them. Improper installation can create gaps and reduce the effectiveness of this type of insulation, so you may want to consider using professional for optimal thermal efficiency. Cellulose Blown Insulation Available through professional insulation installers or at your local big box store, cellulose insulation costs substantially less than fiberglass batts. It is generally worth it to pay for professional installation, though, which does increase the total cost. Cellulose insulation is a loose fill material blown into your attic at a uniform depth, enabling it to completely blanket the space for a gap-free coating. A pro will be able to ensure that the insulation is evenly installed for ideal performance.

This type of insulation has the added benefit of being made from recycled newspapers, a "green" feature that appeals to many homeowners. Although the cellulose is treated with a fire retardant, it can be susceptible to insect infestation and mold, so you’ll want to confirm that it is appropriate for use in your home. Spray Foam Insulation Initially used almost exclusively in commercial applications, spray foam insulation has become quite popular in private homes over the last several years. This amazing material expands to many times its original volume, allowing it to squeeze into tight nooks and crannies and creating a complete cover of insulation.

Spray foam provides high R-values and draft free insulation. It can actually insulate too well in some cases: if you’re considering applying spray foam insulation to the underside of your roof, you need to make sure your shingles won’t accidentally overheat! Also, keep in mind that professional installation is practically a must for spray foam insulation: they have specialized tools to ensure even installation as well as the skills to reduce waste of this expensive material.

Whether you select batt, cellulose, or spray foam, ensuring that your attic is well insulated can help you reduce your energy costs as much as 30%. Just imagine all the good that will do for your wallet as well as the planet. Contact your local insulation installer today to learn more about which type of insulation is right for your attic. Author: Matt Gallo Matt Gallo is is a home improvement hobbyist and the Internet Marketing Manager for Prospect Genius, a leading provider of online local advertising . Article Source: http://EzineArticles.com/?expert=Matt_Gal Protect Your Home With Insulated Curtains Antique Rugs On Line One of the quickest and most affordable ways to insulate your home is to dress your windows with thermal. Insulated | Stainless Steel Water Bottle insulated. … NEW Double Insulated STAINLESS STEEL Sport WATER BOTTLE Paypal US $9.99, 24 Water Bottle Coolers Insulated Assorted With Clip Paypal US $9.95. Structural Insulated Panel Assn. Annual Conference April 20-23 … Structural Insulated Panel Assn. Annual Conference April 20-23, 2009 in Chicago. 03/04/2009. The Structural Insulated Panel Association will hold its Annual Meeting & Conference April Bali s property market insulated – Indonesia and World Tourism News Bali s property market insulated . February 27th, 2009. AAP. Australian villa owners say Bali s property market is more resilient than that in their own country.

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