Steel specific heat

With some materials, there are specific heat treatments that are known to reproduce the worst effects of the heat of welding. It is recommended, therefore, that in tests made to qualify a material for a particular service environment, in addition to the exposure of welded test specimens in order to observe effects of welding heat, specimens should be included that have been given a controlled abusive or sensitising heat treatment. As an illustration, austenitic stainless steels may be held at 650-700° forO-5-1 h, followed by testing for susceptibility to intercystalline attack as in ISO 3651-1 or -2 1976. 

J/g °C. This explains why swimming is not a popular pastime in northern Minnesota in May. Even if the air temperature rises to 90°F, the water temperature will remain below 60°F. Metals have a relatively low specific heat (Table 8.1). When you warm water in a stainless steel saucepan, for example, nearly all of the heat is absorbed by the water, very little by the steel. 

Stainless steel accessories in cars are usually plated with chromium to give them a shiny surface and to prevent rusting. When 5.00 g of chromium at 23.00°C absorbs 62.5 J of heat, the temperature increases to 50.8°C. What is the specific heat of chromium ... 

Self-Test 7.2B The temperature of 5.5 g of stainless steel is increased from 20.°C to 100.°C. What is the change in the entropy of the stainless steel The specific heat capacity of stainless steel is 0.51 J-(°C) -g 1. 

The quantity of heat (J/kg/K) required to raise the temperature of unit mass of the substance through 1 °C. The specific heat of rubber (around 2000) is much higher than that of metals (around 400 for steel) and it is therefore much more expensive to heat rubber than the mould, mandrel or last on which it is cured. 

A solution of 500 kg of Na2S04 in 2500 kg water is cooled from 333 K to 283 K in an agitated mild steel vessel of mass 750 kg. At 283 K, the solubility of the anhydrous salt is 8.9 kg/100 kg water and the stable crystalline phase is Na2SO4.10H2O. At 291 K, the heat of solution is —78.5 MJ/kmol and the specific heat capacities of the solution and mild steel are 3.6 and 0.5 kJ/kg deg K respectively. If, during cooling, 2 per cent of the water initially present is lost by evaporation, estimate the heat which must be removed. 

A large fraction of the iron and steel produced today is recycled scrap. Since scrap does not require reduction, it can be melted down directly in an electric arc furnace, in which the charge is heated through its own electrical resistance to arcs struck from graphite electrodes above it. The main problem with this process is the presence of tramps (i.e., copper from electrical wiring, chromium, nickel, and various other metals) that accompany scrap steel such as crushed automobile bodies and that lead to brittleness in the product. Tin in combination with sulfur is the most troublesome tramp. Only the highest quality recycled steel—specifically, steel with no more than 0.13% tramps—can be used for new automobile bodies, and usually reprocessed scrap has to be mixed with new steel to meet these requirements. 

A fermentation broth contained in a batch-operated stirred-tank fermentor, 2.4m in inside diameter D, is equipped with a paddle-type stirrer of diameter (L) of 0.8 m that rotates at a speed Af = 4s -. The broth temperature is maintained at 30 °C with cooling water at 15°C, which flows through a stainless steel helical coil that has a 50 mm outside diameter and is 5 mm thick. The maximum rate of heat evolution by biochemical reactions, plus dissipation of mechanical energy input by the stirrer, is 51000 kcal h , although the rate varies with time. The physical properties of the broth at 30 °C were density p = 1000 kg m " , viscosity p = 0.013 Pa s, specific heat Cp = 0.90 kcal kg °C , and thermal conductivity K = 0.49 kcal h m °C = 0.000136 kcals m °C . ... 

The specific heat capacity of stainless steel is 0.51 J-rCp-g . (a) Calculate the heat that must be supplied to a 500.0-g stainless steel vessel containing 450.0 g of water to raise its temperature from 25.0°C to the boiling point of water, 100.0°C. (b) What percentage of the heat is used to raise the temperature of the water (c) Compare these answers with those of Exercise 6.17. 

An exothermal reaction is to be performed in the semi-batch mode at 80 °C in a 16 m3 water cooled stainless steel reactor with heat transfer coefficient U = 300 Wm"2 K . The reaction is known to be a bimolecular reaction of second order and follows the scheme A + B —> P. The industrial process intends to initially charge 15 000 kg of A into the reactor, which is heated to 80 °C. Then 3000 kg of B are fed at constant rate during 2 hours. This represents a stoichiometric excess of 10%.The reaction was performed under these conditions in a reaction calorimeter. The maximum heat release rate of 30Wkg 1 was reached after 45 minutes, then the measured power depleted to reach asymptotically zero after 8 hours. The reaction is exothermal with an energy of 250 kj kg-1 of final reaction mass. The specific heat capacity is 1.7kJ kg 1 K 1. After 1.8 hours the conversion is 62% and 65% at end of the feed time. The thermal stability of the final reaction mass imposes a maximum allowed temperature of 125 °C The boiling point of the reaction mass (MTT) is 180 °C, its freezing point is 50 °C. 

A steam boiler is made of steel and weighs 900 kg. The boiler contains 400 kg of water. Assuming that 70% of the heat is delivered to the boiler and water, how much heat is required to raise the temperature of the whole from 10°C to 100°C The specific heat of steel is 0.11 kcal/kg K. 

Determine the condensate load. The first step in selecting a steam trap for any type of equipment is determination of the condensate load. Use the following general procedure. a. Solid materials in autoclaves, retorts, and sterilizers. How much condensate is formed when 2000 lb of solid material with a specific heat of 1.0 is processed in 15 min at 240°F by 25-psig steam from an initial temperature of 60°F in an insulated steel retort ... 

Determine the expansion factor and the meter area factor. Since steam is a compressible fluid, the expansion factor Y must be determined. For superheated steam, the ratio of the specific heat at constant pressure cp to the specific heat at constant volume cv is k = cp/cv = 1.3. Also, the ratio of the differential maximum pressure reading hw, in in of water, to the maximum pressure in the pipe, in psia, equals 120/246.7 = 0.454. Using the expansion-factor curve in the ASME Fluid Meters, Y = 0.994 for ft = 0.5999, and the pressure ratio = 0.454. And, from the same reference, the meter area factor Fa = 1.0084 for a steel meter operating at 640°F. 

As obtained in this manner, cementite is grey in colour and very brittle it can be powdered in the hand. Its hardness is 3 2 to 3 3 density4 at 21° C. 7 396 molecular volume 24 34. It crystallises in pseudo-hexagonal form.5 The specific heat of cementite, as calculated from data obtained with carbon steels, is 0 1581.6... 

In a method used by Thomsen the given liquid, e.g. a solution, was used as the calorimeter liquid and heat given to it by the combustion of hydrogen or by a chemical reaction (e.g. the dilution of sulphuric acid, in a vessel immersed in the liquid. A known mass of heated solid can also be immersed in the liquid in a calorimeter. Schiff enclosed the liquid in a platinum vessel of cross-shaped section, containing a thermometer. This was heated to a given temperature and then put into the calorimeter, and stirred round in the water. The liquid was in layers only 1 cm. thick and a rapid equalisation of temperature was thus ensured. Schlesinger heated the liquid electrically and deduced the rise in temperature from the measured increase in volume and the coefficient of expansion. Specific heats of liquids at low temperatures ca,n be determined by a modification of the Nernst calorimeter, in which the liquid in a small steel vessel contained in a... 

De Keen attempted to find the effect of pressure up to and above the critical point, on the specific heat. A steel cylinder enclosing the liquid was surrounded by a jacket of mercury vapour, and the time taken for heating through 50° compared with that when water was in the cylinder. The accuracy of this method is doubtful. He found that the specific heat decreased with increasing pressure near the critical point, and there was a sudden change of specific heat at the critical temperature. With ether ... 

Steel balls at 140 C with a specific heat of 0.50 kJ/kg - C are quenched in an oil bath to art average temperature of SS C at a rale of 35 balls per minute. If the average mass of steel balls is 1.2 kg, the rate of heal transfer from the balls to the oil is... 

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