Steam Calorimeters

Measurements of cv at moderate temperatures were made by Joly in a steam calorimeter. The weight of water condensed from steam blown through a chamber containing a copper globe filled with gas was compared with the weight deposited on a similar but vacuous globe. 

A steam calorimeter was perfected by J. Joly (1886) and used for the accurate determination of specific heats of solids, liquids, and gases. In principle this apparatus consists of a balance, with the specimen hung from one pan and surrounded by an enclosure that can be flooded with steam. The mass of moisture condensing on the specimen, multiplied by the heat of vaporization of water, gives the quantity of heat imparted to the specimen. 

The Joly steam calorimeter ( 6.VIIE) has been used to determine the latent heat of steam 9 by measuring the amounts of steam condensed on the metal bulb first empty and then full of water, from which 4 can be calculated. 

Joly s steam calorimeter An apparatus invented by John Joly (1857-1933) to measure the specific heat capacity of a gas at constant volume. Two equal spherical containers are suspended from the opposite ends of a balance arm. One sphere is evacuated and the other contains the sample gas. The whole apparatus is enclosed in a steam bath, the specific heat capacity of the sample gas being calculated from the difference between the masses of the water that condenses on each sphere. 

Bunsen first developed the ice calorimeter into an accurate instrument, and a steam calorimeter, first used by Joly, was developed and used by Bunsen. ... 

NOTE The moisture content of steam can be measured by means of a throttling calorimeter or by analysis of the sodium content in a sample of condensed steam, using perhaps a specific ion electrode or flame photometer. 

The quality of steam can be measured by a permanently installed throttling calorimeter. 

Figure 2. Test of the flow mixing calorimeter on steam + nitrogen at x = 0.5 (measurements were made at 698 K and 12.3 MPa)...

Figure 14. Schematic picture of a whole body calorimeter with its ventilatory system, a, Fan b, steam c, saturator d, heater e, respiratory heater f, condenser g, respiratory condenser h, gradient layer. Adapted from J6quier et al. (1975).

Specific Heat—The specific heat of particles is determined by heating a given weight of a sample to nearly 100 deg C in a steam bath, and quickly stirring the hot particles into the water in a calorimeter. The temperature rise may thus be determined and the specific heat obtained from this observation and the known masses involved. Most soils, whether loams, sands, or clays, have specific heats ranging from 0.15 to 0.20 cal per g per deg C. 

A tube of mercury formed the inner tube of a Bunsen s ice calorimeter (Fig. l.VIII F see 8.IX M), and was in the centre of a larger tube containing mercury, heated above by a current of steam. The temperature of the central tube, of cross-section A, was uniform, and if / is the distance between two sections with temperatures ti and tz (ti>t2X and q the measured quantity of heat flowing into the calorimeter per sec. ... 

A comprehensive experimental research program to investigate the effects of pressure on the products of steam gasification of biomass is currently underway. A stainless steel, tubular microreactor similar to the quartz reactor described earlier has been fabricated for the experimental work. The pyrolysis furnace used with the quartz reactor system has been replaced in the pressurized steam system by a Setaram Differential Scanning Calorimeter (DSC). The DSC provides for quantitative determination of the effects of pressure on pyrolysis kinetics and heats of reaction. 

EXAMPLE 2.7-3. Energy Balance in Flow Calorimeter A flow calorimeter is being used to measure the enthalpy of steam. The calorimeter, which is a horizontal insulated pipe, consists of an electric heater immersed in a fluid flowing at steady state. Liquid water at 0°C at a rate of 0.3964 kg/min enters the calorimeter at point 1. The liquid is vaporized completely by the heater, where 19.63 kW is added and steam leaves point 2 at 250°C and 150 kPa absolute. Calculate the exit enthalpy of the steam if the liquid enthalpy at 0°C is set arbitrarily as 0. The... 

Surface polarity is of major concern with activated carbons particularly when used for adsorptions from aqueous solution. This can be assessed by water isotherms, but the process is tedious when compared to the use of an immersion calorimeter. The variation of enthalpies of immersion with coverage by surface oxygen complexes is as in Figure 5.47 which indicates the rapid increase in AHj from 32 J g , for a clean surface, to a maximum of 75J g for carbon surfaces possessing surface oxygen complexes, for steam activated olive stones (Section 4.7.4). 

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