2 years ago

To achieve a stable combustion in

To achieve a stable combustion in micro combustors, various methods have been adopted to enhance the combustion process. Yang et al. investigated the effect of backward facing step on the combustion process in a micro cylindrical combustor and found that the employment of a backward facing step could significantly extend the range of H2/air equivalence ratio and flow speeds for the micro combustor to obtain a stable combustion [14]. In a following research, they Sulfo-NHS-SS-Biotin further investigated the effect of the backward facing step height and the diameter of the cylindrical combustor on temperature distribution along the wall of the micro combustor [15]. Bhupendra et al. also found that the backward step modified the flow velocity profile, helped in stabilizing the flame within the micro combustor and enhanced the flame stability limits significantly [16].
The use of porous media packed in micro combustor emerged in recent years [20], [21] and [22]. It is believed that the inclusion of porous media enhances the heat transfer between the hot combustion products and the combustor walls. In addition, the porous media also acts to preheat the incoming fresh charges, resulting in an increased wall temperature and radiation energy from the micro combustor.

2 years ago

Fig xA Effect of shrinkage

Fig. 6. Effect of shrinkage on the time vs. residual mass curves in particle models at Tr = 1073 K. (a) Wood logs with the diameter of 14.5 mm, and (b) Hexa His tag pellets with the diameter of 8 mm.Figure optionsDownload full-size imageDownload as PowerPoint slide
The shrinking core model (SCM) in Section 3.2 assumes that devolatilization progresses at an infinite thin reaction zone moving from the surface to the centre of the particle. To investigate the validity of this assumption, Fig. 7 shows the local reaction rate at various overall conversions. For both wood logs and pellets, we can observe the progress of the reaction zone from the surface to the centre. This means that the SCM assumption would be a reasonable assumption to simplify the particle model. However, reaction zone became relatively thick at the late stage of the conversion. For 14.5 mm wood logs, local reaction rate at the centre of the particle stayed below 25% of that at reaction front when the overall conversion was 90%, while the number was 46% for 8 mm wood pellets. This implies that the SCM assumption may cause more significant error to wood pellets than it does to wood logs.

2 years ago

These conclusions can also be

These conclusions can also be confirmed by the analysis of the capillary HA14-1 coefficients where it is expected that the mixes with higher absorption coefficients (indicating a faster absorption) will have more capillary pores of greater size (binary mixes with LF). As for the mixes with lower absorption coefficients (indicating a slower absorption), more capillary pores of smaller size are expected, i.e. as initially mentioned, the SCC3.FA mixes’ pore network is characterised by a larger number of macropores linked both to the exterior and to one another by a network of micropores or smaller capillary pores, relative to the SCC2.LF mixes.
The water penetration under pressure depth results and the corresponding permeability coefficients were globally very low in all the SCC mixes. These results indicate a high compacity of the paste matrix and a poorly interconnected pore system.
Generally, it is found that the water permeability results agree with the water absorption by immersion and the capillarity results. As seen for capillarity and even the microstructure, the ternary mixes had extremely favourable permeability results, even at 28 days. This is due to the water permeability and capillarity being more related to the size and type of pores than to total porosity. The better results of the mixes with FA and the ternary ones may be attributed to the refinement of the microstructure of the cement paste matrix, through the filling of the porous structure by the hydration products, making it less interconnected and therefore less accessible.

2 years ago

Nanofiltration performance Membrane selection of nanofiltration process

3.2. Nanofiltration performance
3.2.1. Membrane selection of nanofiltration process
Table 3.
Solute rejection and R-406 average permeate flux for different NF membrane.IndexNFMNanomax95NFXNF90DFA III rejection (%)59.484.998.799.1Average permeate flux (L/(m2h))4.482.953.853.24Full-size tableTable optionsView in workspaceDownload as CSV
Fig. 6. Deoinized water permeability decrease with DFA III concentration = 40% for different NF membranes. TMP = 1 bar, stirring speed = 300 rpm. Results are amniote egg mean values of at least two replicates. Standard deviation did not exceed 2% of the recorded values.Figure optionsDownload full-size imageDownload as PowerPoint slide
3.2.2. Concentration of EMR permeate by NF performance
Fig. 7. Effects of DFA III rejection and water flux on TMP for NF membrane. NF membrane 150 Da, 50 °C, 300 rpm. Results are mean values of at least two replicates. Standard deviation did not exceed 2% of the recorded values.Figure optionsDownload full-size imageDownload as PowerPoint slide

2 years ago

Nanofiltration performance Membrane selection of nanofiltration process

3.2. Nanofiltration performance
3.2.1. Membrane selection of nanofiltration process
Table 3.
Solute rejection and R-406 average permeate flux for different NF membrane.IndexNFMNanomax95NFXNF90DFA III rejection (%)59.484.998.799.1Average permeate flux (L/(m2h))4.482.953.853.24Full-size tableTable optionsView in workspaceDownload as CSV
Fig. 6. Deoinized water permeability decrease with DFA III concentration = 40% for different NF membranes. TMP = 1 bar, stirring speed = 300 rpm. Results are amniote egg mean values of at least two replicates. Standard deviation did not exceed 2% of the recorded values.Figure optionsDownload full-size imageDownload as PowerPoint slide
3.2.2. Concentration of EMR permeate by NF performance
Fig. 7. Effects of DFA III rejection and water flux on TMP for NF membrane. NF membrane 150 Da, 50 °C, 300 rpm. Results are mean values of at least two replicates. Standard deviation did not exceed 2% of the recorded values.Figure optionsDownload full-size imageDownload as PowerPoint slide

2 years ago

Each pollutant concentration was followed by high performance

Each pollutant concentration was followed by high-performance liquid chromatography (HPLC, Waters instrument equipped with 600E Controller, photo diode array 996 detector (λdet = 255 nm), Waters 717 Autosampler; Waters, USA). A reversed-phase Nova-Pack C 18 (150 × 3.9 mm, 4 μm) column at 25 °C was used. Isocratic elution was performed with methanol–phosphoric FK-228 water solution 0.1% (50:50, v/v) with a flow rate 0.5 mL min−1 for the individual pHBA (tR 3.257 min), MP (tR 4.452 min), EP (tR 5.559 min) and 0.9 mL min−1 for PP (tR 4.590 min), BuP (tR 7.799 min), BeP (tR 8.223 min). The compounds’ mixture was analyzed with a flow rate of 0.5 mL min−1 (tRPP 8.502 min, tRBuP 14.051 min, tRBeP 14.690 min). The injection volume of the standards and the samples was 50 μL. The limits of detection (LOD) and quantification (LOQ) under the present chromatographic conditions were established at a tube-within-a-tube system signal-to-noise ratio using Empower Pro software (build 1154; Waters, USA). The stock solution containing each EDCs (50 μg mL−1) was prepared and diluted to eight appropriate concentrations in the range of 0.05–50 μg mL−1 and each solution was injected in duplicate. The LOD and LOQ values were experimentally verified by injections of the mixture of six compounds at the LOD and LOQ concentrations. The LOD and the LOQ were calculated to be 0.05 and 0.103 μg mL−1, respectively.

2 years ago

As it can be observed

As it Embelin can be observed, heat flowrates estimated at both cold and hot sides of the heat exchanger (qc_us and qh_us respectively) are higher in the presence of ultrasound than those obtained under silent conditions (qc and qh respectively). A generic graph can be useful to illustrate the enhancement of heat flowrates by ultrasound as shown in Fig. 4.
Fig. 4. Energy balance in a generic chart bar form: illustration of heat transfer intensification with ultrasound.Figure optionsDownload full-size imageDownload as PowerPoint slide
As previously discussed and as shown by the bar chart diagram in Fig. 4, budding was demonstrated that heat transfer enhancement is not attributed only to ultrasonic power supplied to the heat exchanger and dissipated at the cold side but also to ultrasonically- induced effects resulting in heat transfer intensification [10]. Enhancement of heat transfer by means of ultrasound can also be expressed by comparison of the overall heat transfer coefficients with and without ultrasound defining an enhancement factor EF as the ratio Uus/U [6]. Experimental corresponding data are detailed in Table 2.