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61.
Hosain Darvishi Nasser Behroozi-Khazaei Mahmoud Koushesh Saba Zakaria Alimohammadi Himan Nourbakhsh 《International Journal of Food Science & Technology》2021,56(9):4789-4798
The antioxidant, phenol, ascorbic acid, electrode corrosion and engineering factors of concentration process of kiwifruit juice by ohmic heating-vacuum conditions (OHVC) were evaluated and compared with ohmic heating under atmospheric conditions (OHAC). Results showed that the total phenol content was decreased with an increasing voltage gradient for both heating modes. The OHVC can better save the antioxidant capacity and ascorbic acid of concentrated samples than the OHAC. The processing time of OHVC was significantly higher than the OHAC at the same voltage gradient (P < 0.05). The electrode corrosion rate at the vacuum mode was 7- to 40-fold higher than the atmospheric mode. The energy efficiency at OHAC was lower than the OHVC. The energy consumption was found in the range of 3.37 to 3.75 MJ kg−1 water for OHAC and 4.08 to 11.09 MJ kg−1 water for OHVC. The electrical conductivity under the vacuum mode was lower than the atmospheric mode. 相似文献
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This paper presents seasonal‐energy storage of solar energy for the heating of buildings. We distinguish several types of seasonal storage, such as latent, sensible, and chemical storage, among which the thermochemical storage is used and analysed in this research. In the first part, a laboratory heat‐storage tank, which was made in the laboratory for heating, sanitary, and solar technology and air conditioning from the Faculty of Mechanical Engineering, University of Ljubljana, Slovenia, was presented. The experimental model was tested for charging and discharging mode. Two types of numerical models for sorption thermal‐energy storage exist, which are microscale and macroscale (integral). For microscale analysis, the analysis system (ANSYS) model can be used to simulate the behaviour in the adsorption reactor. On macroscale or integral scale, TRaNsient SYStem (TRNSYS) model was used to perform the operation of the storages on the yearly basis. In the second part the simulation of the underfloor heating system operation with a built‐in storage tank was carried out for two locations, Ljubljana and Portoro?. Furthermore, the comparison between a thermochemical and sensible‐heat storage was performed with TRNSYS and Excel software. In this comparison, the focus was on the surface parameters of the SCs and volume of the thermal‐storage tank for the coverage of the energy demand for selected building. With this analysis, we would like to show the advantage of the thermochemical storage system, to provide greater coverage of the energy demand for the operation of the building, compared with the seasonal sensible‐heat storage (SSHS). Such a heat‐storage technology could, in the future, be a key contributor to the more environmentally friendly and more sustainable way of delivering energy needs for buildings. 相似文献
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65.
Md Faisal Md Basir Muhammad Bilal Rakesh Choudhary Joby Mackolil B. Mahanthesh Kottakkaran S. Nisar 《亚洲传热研究》2021,50(6):5439-5466
The impact of Stefan blowing on the MHD bioconvective slip flow of a nanofluid towards a sheet is explored using numerical and statistical tools. The governing partial differential equations are nondimensionalized and converted to similarity equations using apposite transformations. These transformed equations are solved using the Runge–Kutta–Fehlberg method with the shooting technique. Graphical visualizations are used to scrutinize the effect of the controlling parameters on the flow profiles, skin friction coefficient, local Nusselt, and Sherwood number. Moreover, the sensitivities of the reduced Sherwood and Nusselt number to the input variables of interest are explored by adopting the response surface methodology. The outcomes of the limiting cases are emphatically in corroboration with the outcomes from preceding research. It is found that the heat transfer rate has a positive sensitivity towards the haphazard motion of the nanoparticles and a negative sensitivity towards the thermomigration. The thermal field is enhanced by the Stefan blowing aspect. Moreover, the fluid velocity can be controlled by the applied magnetic field. 相似文献
66.
Nohemí Soto-Reyes María Elena Sosa-Morales Roberto Rojas-Laguna Aurelio López-Malo 《International Journal of Food Science & Technology》2022,57(6):3207-3222
Radiofrequency (RF) heating is an alternative emerging technology to conventional thermal methods; it has been employed for food pasteurisation, providing fast and volumetric heating. However, non-uniformity in the heating pattern has been reported. RF pasteurisation has been studied in different liquid foods. This review provides information about the RF heating mechanism and equipment used to pasteurise liquid food to control deteriorative or pathogen micro-organisms and the effect of the RF treatment on the quality of liquid foods. Developing an effective RF pasteurisation for liquid foods requires knowing the food dielectric properties, which determine the heating uniformity, temperature distribution and heating rate. The efficiency of continuous RF heating systems could depend on the fluid rate, resident time and absorbed power. RF heating can pasteurise liquid food, decrease microbial population and preserve the product's nutritional and physicochemical quality. 相似文献
67.
《International Journal of Hydrogen Energy》2022,47(85):36058-36072
The purpose of this study is to investigate the hydrogen generation characteristics of H2-reduced dimethyl ether (DME) steam reforming (SR) catalysts using different heating processes. The effects of the H2 reduction temperature and space velocity were investigated to identify an optimal reaction environment. Both the resistive and induction heating methods were used. The catalysts were prepared by impregnating copper over a γ-Al2O3 support. The Cu/Al2O3 catalysts with different loading amounts of 5–15 wt% Cu exhibited different characteristics when subjected to hydrogen reduction. The variation in acidity had a dominant effect on the DME-SR activity, and 15Cu/Al2O3 that underwent hydrogen reduction treatment at 500 °C attained improved performance at low temperatures and low formation of by-products, allowing for the achievement of its highest H2 concentration of 74.08% at 375 °C. The induction heating reactor had an energy consumption that was about 25% lower than that of the resistive heating reactor. 相似文献
68.
The present article investigates the influence of Joule heating and chemical reaction on magneto Casson nanofluid phenomena in the occurrence of thermal radiation through a porous inclined stretching sheet. Consideration is extended to heat absorption/generation and viscous dissipation. The governing partial differential equations were transformed into nonlinear ordinary differential equations and numerically solved using the Implicit Finite Difference technique. The article analyses the effect of various physical flow parameters on velocity, heat, and mass transfer distributions. For the various involved parameters, the graphical and numerical outcomes are established. The analysis reveals that the enhancement of the radiation parameter increases the temperature and the chemical reaction parameter decreases the concentration profile. The empirical data presented were compared with previously published findings. 相似文献
69.
《International Journal of Hydrogen Energy》2022,47(12):8048-8059
Heat transportation is a novel prospective in many thermal processes and presents dynamic applications in industrial and thermal polymer processing optimization. The importance of heat transportation is noted in heat exchangers, production of crude oils, combustion, petroleum reservoirs turbine systems, thermal systems, porous media, modeling of resin transfer nuclear reactions etc. In view of such thermal applications the main objective here is to examine entropy in unsteady magnetohydrodynamic of Casson fluid flow. Radiation in addition to dissipation and ohmic heating are analyzed. Entropy is scrutinized employing thermodynamic second law. Characteristics of Soret and Dufour are also examined. Main objective here is to examine irreversibility. Dimensionless version of differential system is obtained through suitable variables. The obtained partial differential system is solved through numerical scheme (Finite difference method). Physical features of fluid flow, temperature, entropy optimization and concentration have been explained. Variations of parameters on drag force, Nusselt number and solutal transfer rate are graphically discussed. Higher fluid parameter leads to improve in velocity and entropy rate. Larger values of radiation parameter boost up thermal field. Entropy rate and velocity have reverse trend for magnetic field. An intensification for concentration is found through Soret number. Higher approximation of Reynold number enhances skin friction and velocity. Thermal transfer rate is augmented versus radiation and magnetic variables. 相似文献
70.