Thermal power specific

Textile motors Crane motors Determining the size of motor Sugar centrifuge motors Motors for deep-well pumps Motors for agricultural application Surface-cooled motors Torque motors or actuator motors Vibration and noise level Service factors Motors for hazardous locations Specification of motors for Zone 0 locations Specification of motors for Zone I locations Motors for Zone 2 locations Motors for mines, collieries and quarries Intrinsically safe circuits, type Ex. f Testing and certifying authorities Additional requirements for ciritical installations Motors for thermal power station auxiliaries Selection of a special-purpose motor... 

In this Table, BSS refers to British Standard Specification 2468 1978. and ASME refers to the American Society of Mechanical Engineers Industrial Boiler Sub-Committee of the Research Committee on water in Thermal power stations. 1986 ND. not delectable NS. not specified. 

Y matrix of computed values to be compared with the experimental data yq computed value of the specific thermal power [J m-3 s 1]... 

Oq root mean squared errors for the specific thermal power... 

The computed specific thermal power, i.e., the heat released per unit volume and unit time by the chemical reactions (3.55) and (3.56), is given by... 

In Table 3.4, the comparison is performed in terms of phenol conversion and of the asymptotic values of phenol (Ca,0o) and trimethylolphenol (Cp>co) concentrations. Thus, whereas the data in Table 3.3 account for the accuracy in reconstructing the concentrations and the specific thermal power, the data in Table 3.4 are related to the accuracy in predicting the final values of concentration, which are of more practical interest. 

Moreover, the results are graphically shown in Figs. 3.3—3.6. In detail, Fig. 3.3 shows the results obtained with the kinetic model (3.57) with first-order kinetics. The fitting of concentrations (left) is rather poor in particular, the asymptotic values at the largest reaction times are not correctly estimated. This reduced model underestimates the Anal product concentration and overestimates the final conversion of phenol by more than 7 percent, which corresponds to an error of more than 43 percent on the phenol concentration and of about 13 percent on product concentration (Table 3.4). A better fitting is obtained for the specific thermal power (Fig. 3.3, right). 

Fig. 3.3 Concentrations and specific thermal power computed via model (3.57) with first-order kinetics...

On the contrary, the introduction of a second-order kinetics in this model produces the best results for all the measured variables, as shown in Fig. 3.6 in particular, the errors on concentrations of phenol and product are reduced to about 1.6 and 0.4 percent, respectively, while the errors on the specific thermal power are very small. 

Fig I shows the dependency of specific investment cost of wood chip boilers (top) and pellet boiler (bottom) on the thermal power. Investment cost for fuel feeding system fiom the main storage to the hopper is not included, if used additional cost of 1.800 to 2.200 EUR per boiler have to be considered. 

E. Schmidt [2.8] determined the fin shape, which for a specific thermal power, required the least material. The profile of these fins is a parabola, with its vertex at the tip of the fin. These types of pointed fins are difficult to produce, which is why fins used in practice have either rectangular, trapezoidal or triangular cross sections. 

Thus the constant of proportionality has decreased by about 30% over the life of the core. More accurate relationships between thermal power density and neutron density at different stages of the reactor run may be available from the design calculations or from plant-specific reactor physics data. 

Figure 1 l.I Radioactivity and thermal power of LWR uranium waste. Reprocessed, 150 days after discharge from reactor enrichment, 3% burnup, 30,000 MWd/MT heavy metal specific... 

Boiler controls have seen the most important improvements in recent years. In the past boiler controls were limited to adjust feed water temperatures and monitor flame operation by the implementation of specific safefy sensors like flame, temperature and pressure sensors. Today boiler controls integrate more and more functions three-way valve, pumps, external heat storage, solar panel controls, and so on. In more advanced utility boilers, thermal power is modulated through fan speed modulation. Air-fuel ratio is controlled by an ionization... 

The thermal efficiency of all the systems are falling, but at different rates. The smallest radiator drops from 27% efficiency at 200 kWth to 11% efficiency at 400 kWth. This means that in the process of doubling the thermal output of the reactor the conversion efficiency has dropped by more than half, causing a net loss in power output. On the other hand, the 200 m 2 radiator drops from an efficiency of 36% to 27%, a drop of a third, while the thermal power doubles, generating a net increase in power output (400. 27 > 200. 36). Finally, the weight of the system needs to be examined. One way of expressing this is the inverse specific power (expressed in estimated system kg /power output) vs. the thermal power of the system. This is shown in 6-4. The density per unit surface area of the radiator was fixed at 5 kg/m ... 

The successful operation of 500 MWe thermal power plants in India has enabled to fix PFBR reactor power as 500 MWe. Large sized FBR have not indicated any technologic d problems because of reactor size. Specific capital cost is lower for 500 MWe than for a lower power, say 250 MWe. The design and development efforts needed for 500 MWe and 250 MWe plants are comparable. Pressurised Heavy Water Reactors (PHWR) of 500 MWe are under construction in India. Constructability of 500 MWe PFBR components has been assessed and adequate industrial capability exists within the country. 

This shows that all these systems have already left the experimental R D stage and become an economic reality. They have already demonstrated lower consumption of natural fossil fuels per unit of power generated and lower emission of greenhouse gases and other harmful products. Other advantages over thermal power plants are associated with fuel cell-based power plants. They can be produced in modules, from which power plants of different size and output can be put together. This attribute, known as scalability, facilitates the design and construction of plants adapted to specific local requirements. 

ABSTRACT This study addresses the time-variaut reliability assessment in relation to systems exhibiting a non-stationary random process during their operation, such as thermal-hydrauhc passive systems for advanced reactors, relying on natural circulation. The reliability assessment efforts conducted so far don t deal with this specific aspect the dependence upon time is usually ignored, or at most the system unavaUabUity is intended to he assessed per mission time, during which the parameter values, as t-h parameters for instance, are assumed as constant quantities. The paper presents an effort for a consistent approach to model and evaluate the natural circulation passive systems, in terms of time-variant performance parameters, as for instance mass flow-rate and thermal power, to cite any. 

---