All inlets at different temperatures

Efficiency of electricity-TD1 (Hydrogen only) Current density 

---

Figure VL4.Heat generation in fuel cell (All inlets) at different temperatures...

Fig. 4.33. Measured CO oxidation rate on EBL-fabricated model catalysts with different support materials and particle sizes (a) The inlet gas mixture represented by the parameter (3 = Pco/ Pco + P02) has been scanned up/down at a constant temperature of 450 K, and the rate of CO2 production has been monitored during the gas scan in j3. This has been made for three different samples (a) 750-nm Pt/Si02 (blue), (b) 750-nm Pt/CeOj, (black), and (c) Pt/CeOj, sample (200mn, red, disintegrated particles). Results both from experiments (filled circles) and simulations solid lines) are shown. The arrows indicate which reaction rate branch that has been observed while scanning up/down in (3. A bistable region (hysteresis) is observed for all samples, (b) The bistability diagrams determined from a series of measurements as those shown in (a) at different temperatures (Pt/Si02, blue and open squares) Pt/CeOj, black hatch marks and crosses and the 200-nm Pt/CeOj, red hatched area and open squares). The observed differences can be traced back to a pronounced O-spillover effect on ceria. Note the logarithmic scale for the /3-value (from [29])...

In these equations all of the physical properties ate taken at the mean bulk temperature of the fluid (T, + T0)/2, where 7) and T0 are the inlet and outlet temperatures. The difference in the value of the index for heating and cooling occurs because in the former case the film temperature will be greater than the bulk temperature and in the latter case less. Conditions in the film, particularly the viscosity of the fluid, exert an important effect on the heat transfer process. 

The differences in reactions at different reactor positions was studied by Springmann et al. who reported product compositions for ATR of model compounds as a function of reactor length in a metal monolith coated with a proprietary noble metal containing Rh. As expected, the oxidation reactions take place at the reactor inlet, followed by the SR, shift, and methanation reactions. Figure 32 shows the product concentration profiles for a 1-hexene feed, which are typical results for all the fuels tested. These results show that steam, formed from the oxidation reactions, reaches a maximum shortly after the reactor inlet, after which it is consumed in the shift and reforming reactions. H2, CO and CO2 concentrations increase with reactor length and temperature. In this reactor, shift equilibrium is not reached, and the increase in CO with distance from the inlet is the net result of the shift and SR reactions. Methane is... 

The Fluent code with the RSM turbulence model, predict very well the pressure drop in cyclones and can be used in cyclone design for any operational conditions (Figs. 3, 5, 7 and 8). In the CFD numerical calculations a very small pressme drop deviation were observed, with less than 3% of deviation at different inlet velocity which probably in the same magnitude of the experimental error. The CFD simulations with RNG k-e turbulence model still yield a reasonably good prediction (Figs. 3, 5, 7 and 8) with the deviation about 14-20% of an experimental data. It considerably tolerable since the RNG k-e model is much less on computational time required compared to the complicated RSM tmbulence model. In all cases of the simulation the RNG k-< model considerably underestimates the cyclone pressme drop as revealed by Griffiths and Boysan [8], However under extreme temperature (>850 K) there is no significant difference between RNG k-< and RSM model prediction. 

In this formula the average heat-transfer coefficient is based on the arithmetic average of the inlet and outlet temperature differences, and all fluid properties are evaluated at the mean bulk temperature of the fluid, except /j., which is evaluated at the wall temperature. Equation (6-10) obviously cannot be used for extremely long tubes since it would yield a zero heat-transfer coefficient. A comparison by Knudsen and Katz [9, p. 377] of Eq. (6-10) with other relationships indicates that it is valid for... 

Below are listed the radial profiles for two axial positions within the reactor. Notice that at Z = 0.2, there are significant radial gradients while by Z = 0.6 these gradients are all but eliminated. If the inlet and coolant temperatures are around 360°C, then the centerline and inner wall temperatures at Z = 0.2 are 417°C and 385°C, respectively, giving a radial temperature difference of 32°C. 

We will assume that the network is carrying liquid at constant temperature, so that the specific volume is the same all along the pipe. To retain p, zi, V and P2,zi as the boundary conditions, the pressures and heights downstream of each conductance have been labelled Pm.i,Zmj ( m for midway). We may expand the pressure and height differences between pipe inlet and outlet as follows ... 

Reaction rates were measured in the absence of MTBE in a thermostated packed-bed reactor. The reactor was fed with pure isobutene (IB) and methanol (MeOH), with a molar ratio IB/MeOH (Ri/a) between 0.5 and 2. It was operated isothermically in a differential regime, in the absence of mass transfer control. The experiments were carried out at four different temperatures in the range 318-363 K, and the pressure was kept at 1.6 MPa to assure that all the compounds involved in the reaction are in the liquid state. The sulfonic macroporous resin with a styrene-divinylbenzene matrix Bayer K2631 was used as the catalyst. The reactor inlet and outlet were analyzed by a gas chromatograph with a FID detector. Reaction rates were determined from these compositions at the steady state. 

---