Heating aluminum block

The Mel-Temp apparatus (Fig. 3) consists of an electrically heated aluminum block that accommodates three capillaries. The sample is illuminated through the lower port and observed with a 6-power lens through the upper port. The heating rate can be controlled, and with a special thermometer the apparatus can be used up to 500°C, far above the useful limit of silicone oil (about 350°C). It is also available with a digital thermometer. 

Small quantities placed in a heated aluminum block and exploded within 30 sec. 

Electrical heating is accomplished with resistance bauds or ribbons which must be electrically insulated from the machine body but in good thermal contact with it. The heaters must be carefully spaced to avoid a succession of hot and cold areas. Sometimes they are mounted in aluminum blocks shaped to conform to the container walls. Their effective temperature range is 150 to 500°C (about 300 to 930°F). Temperature control is precise, maintenance and supervision costs are low, and conversion of electrical energy to useful heat is almost 100 percent. The cost of electrical energy is usually large, however, and may be prohibitive. 

The reaction mixtures are cooled by placing the 96-well PGR plate on top of a 96-well aluminum block chilled on ice. Heat-shock of 42°C is accomplished by placing the plate in a water bath. Recooling on ice is done first by placing the plate in an ice-water bath and then by placing the plate on top of a 96-well aluminum block chilled on ice. 

The reactor was heated by resistance wires wound in massive aluminum blocks placed around the reactor. The reactor temperature was measured at every inch of the catalyst height by traversing a thermocouple in a thermowell placed along the reactor bed. The reactor was operated at nearly isothermal conditions (1.5C° radial differences). 

This group has further developed multitechnique cells, and designed a cell for SAXS/WAXS and XAFS, and SAXS/WAXS/XAFS and UV-vis spectroscopy (Beale et al., 2006 Grandjean et al., 2005). They reported use of this cell to investigate hydrothermal crystallization processes of inorganic catalysts such as CoAPO-5. The synthesis cell design was simple in concept essentially a mini-autoclave, with a usable volume of 2 mm3, and mica windows, heated by an insulated aluminum block. 

Weigh accurately about 200 mg of a dned, extracted wood meal (40-60 mesh) with known moisture and extractives contents or 50 mg of a dned, purified lignin preparation The specimen, 7ml of 2M NaOH, and 0 4ml of freshly distilled nitrobenzene are placed m a 10-ml stainless steel bomb (Note 1) The bomb is sealed tightly with a screw cap fitted with a Teflon gasket and heated at 170°C for 2 5h m an electrically preheated (170°C), thermostated aluminum block with six holes to accommodate the cylindrically shaped bombs or in a thermostated oil bath The bomb is shaken occasionally and, after the heating period, is removed from the heater and cooled with ice water The oxidation mixture is transferred to a liquid-liquid extractor, and extracted continuously with CHCI, for 4h to remove nitrobenzene reduction products and any excess nitrobenzene The oxidation mixture is acidified to pH 3-4 with cone HC1, and further extracted continuously with CHCI, for 48 h The solvent from the second CHCI, solution is removed at 40°C under reduced pressure to obtain the nitrobenzene oxidation mixture The mixture is then dissolved m 5 ml of CH2C12 and transferred to a 10-ml volumetric flask The solution is made up to 10 ml... 

SOLUTION A wood block is subjected to solar heat flux. The surface temperature of the block is to be determined, and to be compared to the value for an aluminum block. 

Discussion The temperature profiles for both the v/ood and aluminum blocks at f = 20 min are evaluated and plotted in Fig. 4-33 using EES. At a depth of X = 0,41 m, the temperature in both blocks Is 20.6 C. At a depth of 0.5 m, the temperatures become 20.rc for v/ood and 20.4X for aluminum block, which confirms that heat penetrates faster and further in metals compared to nonmetals. 

A thick aluminum block initially at 20 C is subjected to constant heat flux of 4000 W/in by an electric resistance heater whose top surface is insulated. Determine how much the surface temperature of the block will ri.se after 30 minutes. 

S Repeat Prob. 4-84 for the case where the aluminum block is inserted into the furnace on a low-conductivity material so that the heat transfer to or from the bottom surface of the block is negligible. 

For ordinary laboratory work, a modified Hickman still (Fig. 1-39) is convenient. Volatile impurities and gases present in the liquid to be distilled must first be removed so that frothing wiU not occur in the still. This is done by placing the liquid in an ordinary flask, which is then evacuated and gently warmed. After all of the volatile impurities have been removed, the liquid is transferred to the still. The latter is connected to the vacuum system by means of a large connector in order to minimize pressure drop in the system. The still is heated by an aluminum block which is bored to accommodate the bottom of the still to a depth of about 15 mm and which is wrapped with nichrome wire serving as a heater. The wire is best insulated from the block by asbestos paper, and a layer of asbestos paper should be placed between the still and the aluminum block. As the liquid is heated, it evaporates and collects on the condenser from which it drips... 

Activity tests were performed in a single-pass fixed bed reactor system containing two parallel reactors with 1 cm catalyst (20-40 mesh). The reactors werc placed in two cylindrical aluminum blocks heated electrically. The reaction temperature was controlled within l°C. An... 

Pyrolysis Procedure. The shale oil samples were stressed at conditions similar to the petroleum refining process known as delayed coking (6). These conditions are 450°C and about 90 psi pressure. Each Thermal stress was conducted in a 1/4 inch o.d. 316 stainless steel tube fitted with a stainless steel valve via a Swagelok connection. The tube, with a weighed amount of sample (approximately 0.1 g), was attached to a vacuum system, cooled to -78°C, and pumped to remove air. The tube was then thawed and the cooling/pumping process repeated. The tubes were heated by inserting them into 9/32-inch holes in a six-inch diameter aluminum block fitted with a temperature controller. 

Electric heating elements can be sealed within aluminum blocks to provide a more uniform heat distribution and a protective measure of safety in hazardous, explosive environments. Cooling channels can also be designed into the aluminum blocks to provide external cooling for the vessel. 

In the closed reflux spectrophotometric method (Standard Method 5220 D), a standardized colorimetric reagent, based on dichromate, is provided in a sealed vial. Test samples are added to the vial and heated to 150 °C for 2 h in an aluminum block with appropriate holes to accommodate the vials. After cooling, the... 

---