Heal generation

These deratings are meant only for non-magnetic enclostires. where the heal generated is only through induced electric currents (hR) and hence low. There are no hysteresis or eddy current lo.sses. 

If the heal generated by induced currents (there are no magnetic losses) on load on per phase basis is In the main conductor, due to I, = - I , ... 

At a certain depth, the current density reduces to Me = 0.368 of the value at the surface. This depth is termed the depth of penetration, 5p. Of the total heal generated in such conductors, alinosl 80% occurs within this depth (annulus). In other words, around 90% of the total cunenl heal generated 0.9 = 0.8 is concentrated in this area alone. This depth can be represented by... 

In recent years, proprietary catalysts lor advancement have been incorporated in precatalyzed liquid resins. Thus only the addition of bisphenol A is needed to produce solid epoxy resins. Use of the catalysis is claimed to provide resins free from branching which can occur in conventional fusion processes. Additionally, use of the catalysts results in rapid chain-extension reactions because of the high amount of heal generated in the processing. 

JOULE LAW. The quantity of heal generated by a steady electric current is proportional to live resistance of file conductor in which the heat is generated, to Ihe square of the current, and to the lime of its duration H = KRl t. If the resistance is in ohms, the current in amperes, the lime in seconds, and the heal in calorics, the constant K has the value 0,2390 calorics/joule. 

The function of the chelator is to complex the ferrous ion and thus limit the concentration of free iron. Redox systems appear very versatile, permitting polymerization at ambient temperatures and the possibility of control of the rate of radical initiation versus polymerization time. This would thus permit control of heal generation and the minimization of reaction time. The use of the redox system ammonium persulfate (2 mmol) together with sodium pyrosulfite (Na S Oj 2.5 mmol) together with copper sulfate (0.002 mmol) buffered with sodium bicarbonate in I liter of water form an effective redox system for vinyl acetate emulsion polymerization. The reaction was started at 25 C and run nonisothermally to 70 C. The time to almost complete conversion was 30 min (Warson, 1976 and Edelhauser, 1975). 

The late of metabolic heal generation may go up by six times the resting level during total body shivering it) cold weather. 

The rate of heal generation in a medium may vary with time as well as position within the medium. When the variation of heat generation with position is known, the total rale of heat generation in a medium of volume 1/can be determined from... 

The thermal conductivity is given to be constant, and there is no heal generation in the billet. Therefore, the differential equation that governs the variation... 

Starting with an energy balance on a spherical shell volume clement, derive the one-dimensional transient heat conduction equation for a sphere with constant thermal conductivity and no heal generation. 

Z-Xl Water flows through a pipe at an average temperature of VO C. The inner and outer radii of the pipe are rf = 6 cm and rj = 6.5 cm. respectively. The outer surface of the pipe is wrapped with a thin electric heater that consumes 300 W pet m length of the pipe. The exposed surface of the heater is heavily insulated so that the entire heal generated in the heater is transferred to the pipe. Heat is transferred from the inner surface of the pipe to the water by convection with a heat transfer coefficient of h = 85 W/m K. Assuming constant thermal conductivity and one-dimensionat heat transfer, express the mathematical formulation (the differential equation and the boundary conditions) of the heal conduction in the pipe during steady operation. Do not solve. 

C What is heal generation Give some examples. 

C An iron is left unattended and its base temperature rises as a result of resistance healing inside. When will the rate of heal generation inside the iron be equal to the rate of heat loss from the iron ... 

Analysis Heat is generated in the wire and its temperature rises as a result of resistance heating. We assume heal Is generated uniformly throughout the wire and is transferred to the surrounding medium in the radial direction. In steady operation, the rate of heat transfer becomes equal to the heal generated within the wire, which is determined to be... 

Heat is generated steadily in a 3-cm-diaineter spherical ball. The ball is exposed to ambient air at 26°C with a heat transfer coefficient of 7.5 V/m °C. The ball is to be covered with a mateiial of thermal conductivity 0.15 W/m C. The thickness of the covering material that will maximize heal generation within the ball while maintaining ball surface temperature constant is... 

Consider transient one-dimensional heat conduction in a plane wall of thickness /. with heal generation e(x, l) that may vary with time and position and... 

Noie that in the case of no heal generation and t = 0.5, the explicit finite difference formulation for a general interior node reduces to T , = (T/,-1 +, )/2, which has the interesting interpretation that the temperature... 

Consider steady heat conduction in a plane wall whose left. surface (node 0) is maintained at 30°C while the right surface (node 8) is subjected to a heat flux of 1200 W/mT Express the finite difference formulation of the boundary nodes 0 and 8 for the case of no heal generation. Also obtain the finite dif-... 

S-S2 Consider steady two-dimensional heat transfer in two long solid bars whose cross sections are given in the figure. The measured temperatures at selected points on the outer surfaces are as shown. The thermal conductivity of the body is k = 20 W/m C, and there is no heal generation, Using the finite difference method with a mesh size of A.ic = Ay = 1.0 cm,... 

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