超声波对开水器内CaCO 3 结垢行为及其形态的影响

By using distilled water as solvent and microwave and ultrasonic as assistant methods,the nicotine extracting technology was studied with orthogonal experiments.The results showed that: the factors in order of their effects on nicotine yield were powerextraction timeratio of liquid to solid,and the effects of power in the two assistant methods were extremely significant.The optimal extracting conditions were: 1) microwave method: power 230W,extraction time 70 seconds and ratio of liquid to solid 40∶1;2) ultrasonic method: power 400w,extraction time 25 minutes and ratio of liquid to solid 80∶1.The extracting yield by microwave method was higher than that by ultrasonic method,and it was 11 times higher than that by distilled water alone under the same time,temperature and ratio of liquid to solid conditions.

In 2014, the first demineralization plant, using nanofiltration (NF) membrane coupled with renewable energies was realized at Al Annouar high school of Sidi Taibi, Kenitra, Morocco. This project has revealed difficulties related to the membrane performances loss (pressure increase, flux decline, poor water quality of the produced water and increase of energy consumption), as consequences of membrane fouling. To solve this problem, an autopsy of the membrane was done in order to determine the nature and origin of the fouling. The samples of membrane and fouling were then analyzed by scanning electron microscopy using a scanning electron microscope (SEM) connected with an energy dispersive X-ray (EDX) detection system and X-ray diffractometer (XRD). Moreover, three cleaning solutions (hydrochloric acid, nitric acid and sulfuric acid) were tested and assessed in a single cleaning step to find the suitable one for the fouled membrane to regain its initial permeability and performances. The analysis of the experimental results showed that the fouling layer is mainly composed of calcium carbonate (inorganic fouling). Results showed also that the permeability is improved by the hydrochloric acid cleaning (pH=3) with a cleaning efficiency of 93%. Cleaning efficiency did not exceed 75 % with nitric acid (pH=3) and 40 % with sulfuric acid (pH= 3).

Objective To fabricate an ultrasound/fluorescence bi-modal contrast agent by encapsulating fluorescent quantum dots into polymeric ultrasound contrast agent microbubbles.Methods Polylactic acid (PLA,500 mg),(1R)-(+)-camphor (50 mg) and CdSe/ZnS quantum dots (0.5 ml,2.3 μmol/L)were dissolved or dispersed in dichloromethane (10 ml) to form in an organic phase.Ammonium carbonate solution and poly (vinyl alcohol) solution were employed as the internal and external water phase,respectively.The fluorescent microbubbles were generated using double emulsion solvent evaporation and lyophilization methods.The morphology and illumination were characterized by scanning electron microscopy (SEM) and fluorescence spectrophotometry.Synchronized contrast-enhanced ultrasound and fluorescence imaging was acquired by injecting fluorescent microbubbles into the silicone tube coupled to a self-made ultrasound/fluorescence imaging device.Ultrasound/fluorescence bi-modal in vivo imaging was acquired on the kidney of New Zealand rabbits and suckling mice.Results The fluorescent microbubbles were hollow spheres with an averaged diameter of (1.62 ± 1.47) μm.More than 99％ of these microbubbles were less than 8 μm in diameter,which meeted the size criteria for ultrasound contrast agents.The fluorescence emission peak of the microbubbles appeared at 632 nm,indicating that good luminescence properties of quantum dots were maintained.In vitro ultrasound/fluorescence imaging showed no echoic signal when the silicone tube was filled with saline,but there was a strong echo when filled with fluorescent microbubbles.The liquid column with fluorescent microbubbles emitted red luminescence under ultraviolet irradiation.The kidney of the rabbit was remarkably enhanced after the administration of fluorescent microbubbles.Bright fluorescence could be observed at the injection site of the suckling mice via subcutaneous injection.Conclusions A bi-modal but single contrast agent based on polymeric microbubbles has been successfully fabricated for the use of ultrasound and fluorescence imaging.It retains the good characteristics of both echogenicity and fluorescence,which complement each other in case of limitations imposed by uni-modal,single agents. Key words: Ultrasonography; Fluorescence imaging; Microbubbles; Contrast media; Microscopy

The article contains the results of the experimental research of the air heat pump for the preparation of domestic hot water (DHW). An installation consisting of a modular heat pump for hot water connected to two storage tanks with a capacity of 130 dm3 each was the object of the research. The article presents the results of investigations on the influence of the supply air temperature in the evaporator cycle and the variable heat load of the condenser on the heating capacity of the heat pump and the coefficient of performance (COP). The tests were carried out for water heating cycles in the storage tank from room temperature to 50 °C. The research shows that heating water in a 130 dm3 storage tank with ventilation or external air at a temperature above 15 °C takes an average of 2 h, and the heat pump consumes approx. 2.2 kWh of energy per heating cycle. Pump operation in winter is possible with the use of ventilation air, but with the discharge of air cooled outside the building. In order to ensure conditions for effective compressor operation, it is advisable to gradate heat load of the heat pump. The optimal solution is to use a circulating pump with smooth regulation of performance. The air source heat pump for DHW heating is an ideal solution for heating systems equipped with solid fuel boilers. It is a maintenance-free and economical system for producing domestic hot water outside the heating season.

Purpose - The purpose of this study is to apply a cost effective ultrasonic odor reduction method that generated micro-bubbles using ejector to the Southeast Asian wastewater market. Research design, data, and methodology - A leather maker located in Ansan-city, Gyunggi-do, South Korea was sampled from the collection tank to select experimental materials. Experimental setup consisted of circulating water tank-air ejector-ultrasonic device, and circulating wastewater. Sample analysis was performed by CODcr, T-N, T-P, and turbidity by the National Environmental Science Institute. Results - Experimental results show that it is most effective in removing odors when the frequency range of ultrasonic wave is 60∼80 Khz and the output is 200 W. It showed that the concentration of complex odor dropped from a maximum of 14,422 times to a minimum of 120 times. Also, analysis of ammonia and hydrogen sulfide in specific odor substances has shown that they were reduced from 1.5 ppm to 0.4 ppm and from 0.6 ppm to 0.1 ppm, respectively. Conclusions - It is possible to shorten more than 12 hours in the treatment of micro-organisms. It can be seen that the processing time of odor after ultrasonic treatment in the pre-treatment facility is reduced by 25% when compared to the resultant micro-organisms after the chemical treatment, that is, the time of the bio-treatment of micro-organisms. Based on the results, it was confirmed that the pre-treatment method using the ultrasonic and the air ejector device of the experiment shows the effect of reducing the water pollutants and odor more effectively in a relatively short time than the conventional advanced oxidation method.

One of the main issues in incorporating weather dependent sustainable energy sources such as solar- and wind power, into the electrical grid, is the irregularity of power production. The peak hours of power consumption in society, rarely coincide with the peak hours of generation of sustainable energy. The full potential of sustainable energy sources is therefor seldom utilized. In this concern, solar thermal collectors are quite problematic. The need for heating and hot water is largest during the least radiant parts of the day – in the morning, evening and during the night. Most residential solar thermal collectors are connected to large water tanks, in which hot water is stored. These can however, rarely cover an entire households' heating needs, and are most often only used to cover hot water needs. The problem is even more obvious when observing the difference in the heat required and heat generated for an average danish house (built in the 1990's) during an average year, using 25 m2 of solar thermal collectors. Our hope is to prove, that it is possible create a system, which stores large quantities of surplus heat from daytime hours - and from periods with very varying weather conditions, which is more effective than systems using water as a heat storing medium. This is possible by utilizing phase changing materials, which can contain large amounts of latent heat energy, as mediums of heat storage. Using large tanks of for instance lauric acid (which is a naturally occurring lipid that melts at app. 44 oC) could potentially store approximately 2,5 times more usable thermal energy than equivalent water tanks. These tanks would be able to store some of the excess heat energy during peak hours, and provide heat energy when it is needed. In effect, a system such as this could be able to store more energy than water, thereby reducing the amount of wasted heat energy, available during peak hours, considerably. These systems could be effective in areas with large consumptions of residential hot water, such as Scandinavia, or in areas with very varying temperatures, such as deserts, mountain regions etc, ultimately making solar thermal collectors a more viable source of residential heating, reducing the amount of fossil fuels used for heating.

Heated water is very essential for domestic, agricultural, commercial as well as industrial operations. Obtaining hot water usually comes with a cost. Though conventional water heating systems exist, however, the operational cost and environmental impact of this method is contributing seriously to the already worsened energy situation in Nigeria. Solar water heating system (SWHS) is a practical application to replace the conventional electrical water heater. The low efficiency of solar water heaters has been the main reason why many people still prefer the conventional methods. To improve on the performance characteristics of the existing solar water heater, a modified version was developed by re-shaping the solar collector and making it adjustable so that it could attract maximum solar radiation. The pipe was replaced with another pipe of smaller diameter to allow for more heating surface area using the same collector frame. The tank and the sides of the collector frame were lagged with a special polysterine material to reduce heat loss due to radiation and a unidirectional control valve was introduced to the tank so that the already heated water that can be preserved in the tank. Tests were carried out on the existing as well as the modified heaters. The results obtained show a significant improvement on the performance of the SWHS. The inlet average temperature increased form 24.64 oC to 35.14oC while the outlet temperature increased from 51.53oC to 60.73oC which corresponds to an improvement in the performance of the system’s inlet water temperature of 15.65% and outlet water temperature of 15.14%.

The substitution of CFC refrigerants in refrigeration systems, heat pumps and organic Rankine cycles, requests a good knowledge of the heat transfer and pressure drop properties of substitute fluids. A contribution to this international effort is proposed with the study of two hydrofluorocarbon refrigerants (HFC-134a and the zeotropic mixture HFC-407C) and the study of the natural refrigerant ammonia. The HFCs have been experimentally tested on the first test rig developed in the Laboratory of Industrial Energy Systems (LENI) which was substantially modified to cope with ammonia, both in terms of safety requirements and operational conditions. The experimental test section is composed of two concentric tubes, with in tube evaporation of the refrigerant inside the inner tube of counter-current Annular water heating. A new database of the local heat transfer coefficients for the refrigerants HFC-134a, HFC-407C and ammonia together with pressure drop measurements has been collected and used to define and calibrate a new and more general heat transfer model. The two HFC refrigerants have been tested on the test rig developed by Kattan [36]; due to the chemical and the thermophysical properties of ammonia, a new test rig has been designed for the ammonia tests and a new calculation procedure based on the mean temperature measurement on the tube wall has been used. The experimental database covers evaporation tests on plain and on microfin tubes, and with nominal oil concentrations varying from 0 to 5 [%] (by wt.). Detailed modeling is concentrated on the tests on plain tube without oil. Each of the three refrigerants has been evaporated at 4[°C]. The other experimental conditions for the HFCs refrigerants were an inside tube diameter of 10.92[mm], a heat flux range of 2 – 5 [kW/m2] and three mass velocities of G = 100, 200, 300 [kg/(m2s)] visualized as Stratified-Wavy flows (G = 100[kg/(m2s)]), and mainly Annular for the higher mass velocities (G = 200, 300[kg/(m2s)]). The other global conditions for ammonia were an internal tube diameter of 14.00 [mm], a heat flux range of 5 – 70[kW/m2] and eleven mass velocities of G = 10,20,30,40,45,50,55,60,80,120,140[kg/(m2s)], corresponding to Stratified, Stratified-Wavy, Intermittent and Annular flow patterns; complementary tests, varying the mass velocity at constant vapor qualities (x = 20,50,80[%]), have been made in particular to better characterize boundaries between flow patterns. The flow patterns are visualized through glass sections at both ends of the 3.1 [m] long test tube. An extensive review of void fraction models with sensitivity analysis on the actual available flow pattern map has been made. From the 17 correlations reviewed, the models of Taitel-Dukler [71] and Rouhani [79] have been used. Other improvements to the threshold criteria of the Stratified-Wavy to Annular transition, lead to an accurate diabatic map to predict the flow patterns and their transition for very different families of fluids like HFC's and ammonia. A new approach in the prediction of two-phase flow heat transfer has been proposed through the study of each flow pattern separately, according to a new criterion defining the onset of nucleate boiling as a function of the critical convective heat transfer coefficient representative of the location where nucleate boiling might occur. A function based on a pseudo Biot number allows, from the mean heat flux around the tube periphery, to base the model on two different mean heat fluxes applied respectively to the parts of the perimeter in contact with the liquid and the vapor in stratified types of flow. Considering pure convective heat transfer, or mixed convective and nucleate heat transfer, this division allows the use of a common criterion to be applied to each flow pattern. The two-phase flow heat transfer coefficient has finally been obtained as a weighted mean function of the vapor and the liquid heat transfer coefficient with respect to their contact surface with the heated tube. Based on the database of refrigerants HFC-134a and ammonia, the standard deviation of the new heat transfer model is of σ = 27.9[%]. Even if the database showed that the flow conditions were close to, or in the turbulent to laminar flow transition, and even if the major part of the experimental points were purposely obtained close to the various flow pattern transitions, the new model showed very good agreement with the experimental database. Due to the precision of the new flow pattern map and the effectiveness of the onset on nucleate boiling criterion, this new heat transfer model accurately predicts the heat transfer conditions during evaporation. Finally, a new method to model separated flows is proposed, based on partial hydraulic diameters and a mean interface velocity.

Two solar water heaters using a thermosiphon system and each one of them including an internal heat exchanger have been designed and realized at Yamoussoukro (city located at the latitude of 6.58° N and longitude 5.27° W). Each one is made of a solar collector of a 2 m 2 surface and of a storage tank of 95 liters capacity. A comparative study of both thermal performances is realized. The parameters taken into account in the same conditions for the two devices are: the total radiation received by the solar collectors, the ambient temperature, the storage tank hot water temperature, the hot water average temperature in the collector, the hot water average temperature in the heat exchanger, the hot water instantaneous mass flow rate and the instantaneous efficiency of the collector. The level of the average temperature in the storage tank, 45°C for the coconut coir insulation and 55°C for the glass wool insulation, added to the relative simplicity in the realization of these devices and the absence of pumps and other accessories, make them an interesting technological solution. Moreover, the results obtained with the solar water heater by using the coconut fiber as heat insulator show that this system is viable under the local climatic conditions and could be used as a basis for popularization of solar heating water by using local materials as heat insulator. An economic study shows that the solar water heater using coconut fiber makes possible in one year to be more competitive compared to the solar water heater using the glass wood whose gives two years when the imported solar water heater whose investment return ranges between fifteen and sixteen years.

در تحقیق حاضر، برای تأمین حرارت مورد نیاز گلخانه، یک سامانه ی گرمایش خورشیدی مجهز به متمرکزکننده ی سهموی خطی و جمع کننده ی خورشیدی تخت دو منظوره، پیشنهاد گردید. در این سامانه از یک مخزن برای ذخیره حرارت تولید شده استفاده شد. جریان سیال حامل حرارت در داخل متمرکزکننده به‌صورت اجباری و با استفاده از پمپ انجام گرفت. یک جمع کننده ی خورشیدی در داخل گلخانه نصب گردید که در طول روز، وظیفه گردآوری تابش خورشید و ذخیره حرارت در مخزن و در شب نقش مبدل حرارتی برای انتقال حرارت ذخیره شده در سامانه ی گرمایش، به محیط گلخانه را داشت. ارزیابی سامانه ی پیشنهادی در سه سطح دبی سیال عبوری در متمرکزکننده (0/44، 0/75 و 1/5 لیتر بر دقیقه) و دو حالت با و بدون استفاده از جمع کننده ی تخت خورشیدی انجام گرفت. نتایج تحقیق نشان داد که بیشترین بازده متمرکزکننده در بالاترین دبی سیال عبوری حدود 71 درصد به‌دست آمد. با بالا بردن دبی از 0/44 تا 1/5 لیتر بر دقیقه، به‌طور متوسط ذخیره حرارت در مخزن 32/14 درصد بهبود داشت. با استفاده از جمع کننده ی تخت خورشیدی، به طور متوسط 26/67 درصد و با بالا بردن دبی تا 1/5 لیتر بر دقیقه، 30 درصد در مصرف برق گرم کن کمکی، صرفه جویی گردید. در نهایت، بالاترین مقدار سهم خورشیدی سامانه پیشنهاد شده در تحقیق حاضر، 66 درصد بود که در بیشترین دبی سیال عبوری و با استفاده از جمع‌کننده‌ی تخت خورشیدی مشاهده شد.

Seasonal heat storage has great potential to enable renewable heating and seasonal load shifting. Nevertheless, it remains an on going challenge today. The benefits of sorption heat storage are found in the potentially lossless storage, when not including charging and discharging processes, and the prospective of greater volumetric energy densities compared to water. In sorption heat storage not sensible heat is stored, but the potential to regain heat. In the framework of the EU funded project COMTES a closed sorption heat storage demonstrator based on sodium hydroxide as sorbent and water as sorbate was developed and built.<br /><br />The built demonstrator operates on a hybrid basis. Heat is stored in sensible hot water tanks for diurnal storage and in the sorption heat storage system for seasonal storage. This grants the possibility to utilise the benefits of both systems, namely low charging and discharging losses in sensible storage and low heat losses during storage time in sorption storage. The complete system is built into a 7 m long shipping container. A solar collector field with an active area of 18 m² mounted on the container serves to cover the total heat demand.<br /><br />The central component of the sorption system is the interconnected absorber and desorber (AD) and evaporator and condenser (EC) unit. Both units are built as tube bundle falling film heat and mass exchangers similar to a solar thermal chiller. In initial operation with water, 6 kW of water vapour equivalent could be transported from desorber to condenser with a temperature difference between desorber and condenser of approximately 30 K. Nevertheless, absorption tests with sodium hydroxide at a concentration of 50 wt% showed much lower power output below 1 kW. It was found that even though absorption occurred, the process of water vapour absorption is slower than expected. The sodium hydroxide flows over the tube bundle with little water gained, thus releasing little heat. Results from this work and further testing of the speed of absorption have shown that novel heat and mass exchangers are required for sorption heat storage applications.

The article analyses and describes the energy flows in a modern brewery, as planned to be realized in the southern part of Norway. Based on the heating and cooling demands a new concept is developed to enable an innovative and efficient surplus heat upgrade, applied to eliminate current fossil fuel burners. Initially focus is given to minimizing the necessary steam demand in the plant, since the energy efficiency can be increased by substituting this high-quality energy source by pressurised hot water, which can be directly produced by heat pumps. As a result of different system evaluations, the final recommendation is to install an energy storage tank and two heat pump systems with different supply temperature levels. Both heat pumps are utilising the residual heat generated in the tank farm (fermentation) and from the residual water. The first system should be an ammonia heat pump followed by a butane heat pump to produce steam, which also can be stored in a steam accumulator. The second unit should be a carbon dioxide heat pump applied to produce water at 100 ºC. The hot water is stored in a stratified tank with water at temperature levels above 85 ºC.

Removal and Recovery of Phosphonate Antiscalants

Microstructure and microhardness of SiC nanoparticles reinforced magnesium composites fabricated by ultrasonic method

Microstructure and microhardness of SiC nanoparticles reinforced magnesium composites fabricated by ultrasonic method