Heat rate

As an alternative to the thermal or cycle efficiency of Eq. (1.1), the cyclic heat rate (the ratio of heat supply rate to power output) is sometimes used  

This is the inverse of the closed cycle thermal efficiency, when and W are expressed in the same units. 

But a heat rate based on the energy supplied in the fuel is often used. It is then defined 

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The above illustration requires the value of A to be assumed. The assumption may be avoided by determing T for more than one heating rate. Thus E/R may be obtained... 

The temperature-programmed desorption of NO2 shows a maximum rate at 330 K using a heating rate of 7.53°C/sec. Take A to be lO sec , and assume that Eq. XVIII-1 applies. (Note Ref. 344.)... 

Figure Bl.25.11. Temperature progranuued reaetions of 0.15 ML of eoadsorbed with 0.24 ML of NO. Adsorption was done at 150 K and the heating rate was 5 K s (from [23]).

However, die atom will not cool indefinitely. At some point die Doppler cooling rate will be balanced by die heating rate coming from die iiiomentum fluctuations of die atom absorbing and re-emitting photons. Setting diese... 

Several other factors must also be considered with respect to heating conditions. At the front end of a vehicle, ie, at the nosetip, the heating rate is most severe, generally decreasing toward the aft end of the vehicle in instances of laminar flow. Because of this variation in heating conditions, the nosetip... 

The definition of polymer thermal stabiUty is not simple owing to the number of measurement techniques, desired properties, and factors that affect each (time, heating rate, atmosphere, etc). The easiest evaluation of thermal stabiUty is by the temperature at which a certain weight loss occurs as observed by thermogravimetric analysis (tga). Early work assigned a 7% loss as the point of stabiUty more recentiy a 10% value or the extrapolated break in the tga curve has been used. A more reaUstic view is to compare weight loss vs time at constant temperature, and better yet is to evaluate property retention time at temperature one set of criteria has been 177°C for 30,000 h, or 240°C for 1000 h, or 538°C for 1 h, or 816°C for 5 min (1). 

T and by dsc, (onset of decomposition) Thermogravimetric analysis ia argon at 10°C heating rate. 

Kerogen Decomposition. The thermal decomposition of oil shale, ie, pyrolysis or retorting, yields Hquid, gaseous, and soHd products. The amounts of oil, gas, and coke which ultimately are formed depend on the heating rate of the oil shale and the temperature—time history of the Hberated oil. There is Htde effect of shale richness on these relative product yields under fixed pyrolysis conditions, as is shown in Table 5 (10). 

LLDPE can present a certain health hazard when it bums, since smoke, fumes, and toxic decomposition products are sometimes formed in the process. Exposure to burning LLDPE can cause irritation of the skin, eyes, and mucous membranes of the nose and throat due to the presence of acrolein and formaldehyde (81). Toxicity of LLDPE pyrolysis products depends on temperature, heating rate, and the sample size (82—84). 

Fig. 3. Programmed dma scan of a resole phenoHc resin heating rate is 5°C/min.

A 165-MW-class gas turbine/generator has been introduced by another manufacturer. This machine, also developed by scaling up a proven design, features a simple-cycle efficiency of 37.5% a turbine inlet temperature of 1235°C a pressure ratio of 30 1, up from 16 1 on the previous generation and an output of 165 MW for gas fuel firing under International Standards Organization (ISO) conditions (101 kPa, 15°C (14.7 psia, 59°F)). A combined-cycle facihty based around this machine could achieve efficiencies up to 58% or a heat rate of about 6209 kj/kWh (5885 Btu/kWh). 

T. Suzuki, The Development of Coal Firing Power Unit with Ultra High Peformance in Japan, EPRI Eossil Heat Rate Improvement Workshop, Charlotte, N.C,1981. 

Fig. 13. Differential thermal analysis of wood and its components at a heating rate of 12°C pet minute and a gas flow rate of 30 cm pet minute. Sample...

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