Research on Energy Saving Optimization of MVR Distilled Water Machine

Compared with the multi-effect distilled water machine,the mechanical vapor recompression(MVR)distilled water machine has many advantages,and has been a trend to replace the traditional distilled water machine.Based on the conservation equations of mass and energy,this paper designs an MVR distilled water production process and establishes the corresponding thermodynamic model.Effects of the produced water temperature,heat exchange temperature difference,compressor adiabatic efficiency,and pipeline loss to the produced water energy consumption,energy saving rate and coefficient of performance(COP)were studied.Research shows that the MVR distilled water machine is more suitable for occasions with low water production temperature.Appropriate heat exchangers and compressors should be selected to improve comprehensive performance through heat exchange temperature differences and improving adiabatic efficiency.

Analysis of an Evaporator-condenser-separated Mechanical Vapor Compression System

An evaporator-condenser-separated mechanical vapor compression (MVC) system was presented. The better effect of descaling and antiscaling was obtained by the new system. This study focused on the method of thermodynamic analysis, and the energy and exergy flow diagrams were established by using the first and second law of thermodynamics analysis. The results show that the energy utilization rate is very high and the specific power consumption is low. Exergy analysis indicates that the exergy efficiency is low, and the largest exergy loss occurs within the evaporator-condenser and the compressor.

Single-Walled Carbon Nanotube Growth with Non-Iron- Group “Catalysts” by Chemical Vapor Deposition

Various materials have been found to“catalyze”carbon nanotube growth in chemical vapor deposition(CVD)when they become nano-sized particles.These involve not only metals,such as Pd,Pt,Au,Ag,and Cu,but also semiconductors,such as Si,Ge,and SiC.Alumina and diamond nanoparticles also produce carbon nanotubes.These“catalysts”,which are better called“seeds”,can be categorized into two types:one type forms a eutectic liquid or highly-mobile alloy with carbon,and carbon atoms precipitate from the eutectic alloy;the other type remains as a solid phase and form a carbon surface layer during CVD growth.In this paper,we review recent studies of SWCNT growth with these non-iron-group materials and highlight the mechanisms involved.

Estimation of the minimum miscibility pressure for CO_(2)ecrude-oil systems by molecular dynamics simulation

CO_(2)injection is an effective enhanced oil recovery technique for energy security with the benefits of carbon neutrality.To reach the maximum oil recovery,the miscible condition between CO_(2)and oil needs to be maintained in the reservoir,which requires the operation pressure to be higher than the minimum miscibility pressure(MMP).There are two types of MMPs:the first-contact MMP(FC-MMP)and the multi-contact MMP(MC-MMP).In this study,molecular dynamics simulations were performed for the CO_(2)eoil interface system using two simplified digital oil models:a Bakken dead oil with four lumping components and a live-crude-oil model with 50 types of oil molecules but with no asphaltenes and heavy oil fractions.The vanishing interfacial tension method was used to predict the MMP.Different CO_(2)eoil volume ratios were considered to mimic the different degrees of vaporization.To estimate the MMP accurately and rapidly,the interfacial tension in the low-pressure regime was used for the prediction.Consequently,different MMPs were obtained,where the MMP value increased with increasing CO_(2)eoil volume ratio.FC-MMP can be predicted when the CO_(2)eoil volume ratio is sufficiently high.When the CO_(2)eoil volume ratio was approximately 9e10,MMP was closest to the actual MC-MMP value.The condensing and vaporizing mechanism was also studied at the molecular scale.Because pure CO_(2)was used,only the vaporizing effect on MMP occurred.It was found that the intermediate C2eC6 components have the main effect on the MMP calculation.This study can help to establish a computational protocol to estimate FC-MMP and MC-MMP,which are widely used in reservoir engineering.

Single-source precursor derived high-entropy metal–carbide nanowires:Microstructure and growth evolution

In recent years,high-entropy metal carbides(HECs)have attracted significant attention due to their exceptional physical and chemical properties.The combination of excellent performance exhibited by bulk HEC ceramics and distinctive geometric characteristics has paved the way for the emergence of one-dimensional(1D)HECs as novel materials with unique development potential.Herein,we successfully fabricated novel(Ti_(0.2)Zr_(0.2)Hf_(0.2)Nb_(0.2)Ta_(0.2))C nanowires derived via Fe-assisted single-sourced precursor pyrolysis.Prior to the synthesis of the nanowires,the composition and microstructure of(Ti,Zr,Hf,Nb,Ta)-containing precursor(PHECs)were analyzed,and divinylbenzene(DVB)was used to accelerate the conversion process of the precursor and contribute to the formation of HECs,which also provided a partial carbon source for the nanowire growth.Additionally,multi-branched,single-branched,and single-branched bending nanowires were synthesized by adjusting the ratio of PHECs to DVB.The obtained single-branched(Ti_(0.2)Zr_(0.2)Hf_(0.2)Nb_(0.2)Ta_(0.2))C nanowires possessed smooth surfaces with an average diameter of 130–150 nm and a length of several tens of micrometers,which were a single-crystal structure and typically grew along the[11¯1]direction.Also,the growth of the(Ti_(0.2)Zr_(0.2)Hf_(0.2)Nb_(0.2)Ta_(0.2))C nanowires was in agreement with top-type vapor–liquid–solid mechanism.This work not only successfully achieved the fabrication of HEC nanowires by a catalyst-assisted polymer pyrolysis,but also provided a comprehensive analysis of the factors affecting their yield and morphology,highlighting the potential application of these attractive nano-materials.