Post-combustion ratio

In order to provide further insight into the post-combustion ratio and the heat transfer efficiency, the factors that affect the PCR and HTE will be delineated. The factors that affect the PCR and HTE will be discussed separately with the understanding that a complex relationship may exist between the two parameters. The factors that affect the PCR are shown in Table 4, and Fig. 3 demonstrates the primary conditions for postcombustion. The PCR should be kept relatively high, since the fuel consumption decreases with an increase in the PCR at the same HTE (Aukrust, 1993). However, as mentioned, high PCR may lead to problems due to increases in ... 

Selectivity for C02 it represents the C02 uptake ratio to the adsorption of any other gas (typically nitrogen for post-combustion capture, and methane for natural gas). It is an essential evaluation criterion, and affects the purity of the adsorbed gas, which will significantly influence the sequestration of C02. The simplest method to estimate the selectivity factor is to use single-component adsorption isotherms of C02 and nitrogen. 

The inlet velocity significantly modifies the Nu and Sh number profiles near the entrance, as shown in Figure 10.11. As the velocity increases, a lar r axial distance is required for the thermal boundary layer to develop fully. Hence Nu and Sh approach their asymptotic values more gradually. In contrast, other parameters, such as the wall conductivity (kg), heat loss coefficient (hj) to the environment and equivalence ratio (([)), do not have an effect on the Sh profile. While the Nu profile is also independent of these parameters, the location of the discontinuity in the Nu profile shifts due to a shift in the boundary between preheating/combustion and post-combustion zones. 

The identification of the minimal effective selectivity which enables the target separation performances to be attained is often one of the first problems to be solved in the design of membrane processes. For the post-combustion carbon capture challenge, the minimal selectivity can be determined for the set of process performances to be attained a capture ratio, R, of 0.8 (or more) and a permeate purity, j, of 0.8 (or more). Based on the assumptions detailed in the... 

The experimental setup for diode-laser sensing of combustion gases using extractive sampling techniques is shown in Fig. 24.8. The measurements were performed in the post-flame region of laminar methane-air flames at atmospheric conditions. A premixed, water-cooled, ducted flat-flame burner with a 6-centimeter diameter served as the combustion test-bed. Methane and air flows were metered with calibrated rotameters, premixed, and injected into the burner. The stoichiometry was varied between equivalence ratios of = 0.67 to... 

Another important dimensionless variable is the ratio of chamber-to-pintle diameters, djdp. Typical values for this quantity range from 3 to 5 [2]. Finally, the skip distance is defined as the length that the annular flow must travel before impacting the radial holes divided by the pintle diameter, LJd. A typical value for this parameter is around 1 larger skip distances are subject to substantial deceleration of the liquid due to friction against the pintle post whUe very short skip distances may lead to spray impingement on the head-end of the combustion chamber. 

The NO thus formed reacts with hydrocarbon radicals to form HCN or CN radicals which then convert to NHj, similarly as described above. Due to the high activation energy of the reaction 0 + N2 of = 335 kJ/mol, the NO (the NH2 precursor molecule) appears relatively slowly in the high-temperature, post-flame thermal NO . There also is a direct HCN production channel, CH + N2 HCN + N [28]. The fate of NH2 depends on the equivalence ratio. The reaction mechanisms in the different types of flames are more complicated than can be indicated here, since it is very important whether the radicals are present in the burning zone or in the burnt gases. The importance of a specific elementary reaction depends on the concentration of both reaction partners as much as on other kinetic parameters like temperature. The amount of NO produced in these flames is generally smaller than in combustion systems in which fuel nitrogen is present. 

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