Heating of air

The latent heats at 25 C are 7656 kcal/kmol for acetone and 10,490 kcal/kmol for water, and the differential heat of solution of acetone vapor in pure water is given as 2500 kcal/kmol. The specific heat of air is 7.0 kcal/(kmol-K). 

Cp a = specific heat of air at constant pressure AT jj = temperature rise for stoichiometric combustion D = surface average particle diameter Pa = air density Pf = fuel density

equivalence ratio B = mass transfer number... 

A similar argument can be used for a fuelled semi-closed cycle, assuming that it can be regarded as the addition of an open CBT plant and a closed CHT cycle with identical working gas mass flow rates (and small fuel air ratios). Suppose the latter receives its heat supply from the combustion chamber of the former in which the open cycle combustion takes place. If the specific heats of air and products are little different, then the work output is doubled when the two plants are added together, but the fuel supply is also approximately doubled. The efficiency of the combined semi-closed plant is, therefore, approximately the same as that of the original open cycle plant. 

Cps specific heat of air at constant pressure (0.24 approx.) ty = ambient air temp °F... 

Calculate the cubic contents of each room and, using the appropriate air change rate, the amount of heat required to warm the air to the desired temperature by multiplying the volume of air by the difference between the inside and outside temperatures and the specific heat of air. 

Refrigerant condenser coils of heat pump or heat reclaim systems Figure 24.1 shows the sensible heating of air. 

The calculation of Mayer was thrown into a different form by Rankine (1850), who showed that, instead of estimating the mechanical equivalent of heat from the difference of the specific heats of air, one could take Joule s value of the mechanical equivalent and the known ratio of the specific heats, and thence determine the specific heats themselves. 

Secondary air flow, from flow-sheet, 1754.8 kg/h Specific heat of air 1 kJ/kgK... 

The atmosphere itself also has a huge heat storage capacity. In this case, part of the thermal energy is stored in the heating of air, i.e., global warming. Subsequent increase in evaporation means that additional energy is stored in the atmosphere. 

The solar heat absorbed by the atmosphere and the earth s surface goes back into the atmosphere through the evaporation of water. Thermals are formed by the heating of air in contact with a warm surface and the upward emission of energy. 

He began by heating the air with the piston in a fixed position. Thus the volume of air heated was kept constant. The amount of heat (in Btu) needed to heat a fixed weight of air, under constant volume conditions, he called Cy. This is now called the specific heat of air at constant volume. 

Exit air usually is maintained far from saturated with moisture and at a high temperature in order to prevent recondensation of moisture in parallel current operation, with a consequent lowering of thermal efficiency. With steam heating of air the overall efficiency is about 40%. Direct fired dryers may have efficiencies of 80-85% with inlet temperatures of 500-550°C and outlet of 65-70°C. Steam consumption of spray dryers may be 1.2-1.81bsteam/lb evaporated, but the small unit of Table 9.19(b) is naturally less efficient. A 10% heat loss through the walls of the dryer often is taken for design purposes. Pressure drop in a dryer is 15-50 in. of water, depending on duct sizes and the kind of separation equipment used. 

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