Дисертації з теми "Flat Evaporator"
Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями
Ознайомтеся з топ-28 дисертацій для дослідження на тему "Flat Evaporator".
Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.
Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.
Переглядайте дисертації для різних дисциплін та оформлюйте правильно вашу бібліографію.
Tanguy-Sai, Gaëlle. "Concentration de produits laitiers dans les évaporateurs à flot tombant : facteurs limitants et alternatives technologiques." Thesis, Rennes, Agrocampus Ouest, 2018. http://www.theses.fr/2018NSARB318/document.
Повний текст джерелаDairy powders are produced using a two-step process: concentration of the liquid product (membrane, concentration by vacuum evaporation) and drying of the concentrate. Contrary to spray-drying, vacuum concentration has been poorly investigated. However, a better understanding of this unit operation carried out in falling-film evaporators would lead to an improved control of the global process scheme for the production of powders. This PhD project aims to highlight how to enhance the performances of falling-film evaporators; it focuses on two limiting factors of the vacuum concentration: the fouling of the heating surfaces and the maximal viscosity at the outlet of the falling-film evaporators. The contribution of the different product components to the fouling was investigated using a methodology developed at pilot-scale.Our results showed which mineral elements favored the fouling of falling-film evaporators during the concentration of milk microlfiltrate and ultrafiltrate as well as hydrochloric and lactic acid wheys. Besides, two thin-film rotative evaporators of different designs were tested at pilot-scale in order to exceed the maximum dry matter achieved in falling-film evaporators. The feasibility studies were conducted up to the production of powders. The capabilities of the equipment were evaluated according to the functional properties of powders and the specific energy costs relative to the removal of water. In one case, the combination of two rotative evaporators replacing the spray drier constitutes a technological breakthrough in the production of permeate p
Caldas, Pereira Silveira Arlan. "Caractérisation expérimentale et comportement de constituants protéiques et minéraux laitiers en concentration sous vide." Thesis, Rennes, Agrocampus Ouest, 2015. http://www.theses.fr/2015NSARB269/document.
Повний текст джерелаFalling film evaporators (FFE) are widely used in the chemical, refrigeration, petroleum refining, desalination and food industries. In the dairy industry FFE is applied for the concentration of solutions prior to the drying step. Despite the economic importance of the vacuum evaporation process in the manufacture of dairy dried products, the knowledge about the process is mostly empirical. Research aiming to improve the efficiency of the process is therefore necessary. The objective of this PhD project was to characterize experimentally a FFE during the concentration of dairy products by means of thermodynamic and hydrodynamic approaches, in order to study the interactions between the products properties and the operating parameters. A pilot-scale, single-stage falling film evaporator that describes the same process as that of an industrial scale from a hydrodynamic point of view was instrumented and used to establish the mass and energy balances. The evaporation rate and the overall heat transfer coefficient were calculated from the experimental data to follow up the process. A methodology for the determination of the experimental residence time distribution (RTD) functions was developed. RTD functions provide global information about the flow of the products during concentration in a FFE. Increasing of the concentration of skim milk, mass flow rate and the distance covered by the product resulted in an increase in the dispersion of the products particles. The experimental RTD functions were modelled by a combination of two perfectly mixed reactor tanks in series. From the interpretation of this model, two different flows, a main and a minor flow, were identified. The RTD methodology developed on skim milk was applied to sweet whey and lactic acid whey and the study was extended to the formation of fouling during a 5-hour concentration. The mean residence time was more sensitive to identify fouling than the overall heat transfer coefficient and the evaporation rate. This study emphasized the crucial role of process characterization to improve the performance of FFE and product quality
Aza-Gnandji, Cocou Davis Ruben. "Salinity of irrigation water in the Philippi farming area of the cape flats, Cape Town, South Africa." University of the Western Cape, 2011. http://hdl.handle.net/11394/2921.
Повний текст джерелаThis research investigated the nature, source and the spatial variation of the salinity of the water used for irrigation in the urban farming area of Philippi, which lies in the Cape Flats region of the Cape Town Metropolitan Area, South Africa. The irrigation water is mainly drawn from the Cape Flats aquifer, and pumped into ponds for eventual crop irrigation. Water samples were collected in summer and in winter from fifteen selected sites using standard water sampling procedures. Each site consisted of one borehole and one pond. The samples were routinely analyzed for salinity levels, and concentrations of major and minor ions. From the same boreholes and ponds, water was sampled in summer for isotope analysis to assess effects of evaporation on the water quality and salinity. Descriptive statistics were used to display the variation in range of specific ions in order to compare them with the recommended ranges. Geographical Information Systems analysis described the spatial distribution of the salinity across the study area, and hydrogeochemical analysis characterized the various waters and detected similarities between the water samples in the study area and other waters found in the Cape Flats region. In addition, the US salinity diagram classification of irrigation water developed by Richards (1954) was used to assess the current suitability of groundwater and pond water samples collected during the entire sampling period for irrigation activities. The research indicated that the concentrations of some ions such as chloride, nitrate, potassium and sodium exceeded in places in the study area, the target range values set by the Department of Water Affairs and Forestry (DWAF, 1996) and the Food and Agriculture Organization (Ayers and Westcot, 1985). It revealed that borehole and pond water were mostly brackish across the area regarding their total dissolved salts content, and fresh water was only found in the middle part of the study area. The research found that sea water does not intrude into the aquifer of the study area, and the accumulation of salts in groundwater and soil in the study area is mainly due to the agricultural activities and partially due to the natural movement of water through the geological formation of the Cape Flats region. The conceptual model of the occurrence of the salinization process supported these findings. From this investigation it is understood that the groundwater and pond water in the study area were generally suitable for irrigation purposes but they have to be used with caution as the vegetables are classified as sensitive and moderately sensitive to salt according to DWAF Irrigation water guidelines (1996). The quality of these waters was mainly affected by the land use activities.
South Africa
Ali-Adib, Tarif. "Estimation et lois de variation du coefficient de transfert de chaleur surface/ liquide en ébullition pour un liquide alimentaire dans un évaporateur à flot tombant." Phd thesis, AgroParisTech, 2008. http://pastel.archives-ouvertes.fr/pastel-00004544.
Повний текст джерелаWang, Yu-Hsuan, and 王御軒. "Preliminary Study of Dual Loops LHP with Flat Evaporator." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/87967754299842194091.
Повний текст джерела淡江大學
機械與機電工程學系碩士班
97
This paper presented an preliminary study on a copper- methanol based Loop Heat Pipes(LHP) with a 82 mm long, 42mm wide and 10 mm thick flat rectangular evaporator. A novel concept to have dual vapor lines and liquid lines loops design from evaporator to condenser was devised to achieve higher vapor flow rate and reduce the heat leakage to compensation chamber. Thermal performance of loop heat pipe was evaluated experimentally in a fan-heat sink CPU test apparatus with heating area of 31mm x 31mm. After the evaluation, the LHP with 40% filling rate showed the lowest evaporator-to-ambient resistance of 0.83 K/W , corresponding to a heater temperature of 80 ℃ at an input power of 60 watts.
Anand, A. R. "Investigations on Miniature Loop Heat Pipe with Flat Evaporator." Thesis, 2017. http://etd.iisc.ac.in/handle/2005/4308.
Повний текст джерелаChen, Chung-Wei, and 陳仲威. "Visualization and Evaporation Resistance Measurement for Groove-Wick Evaporator of Operating Flat-Plate Heat Pipes." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/56864342489570572865.
Повний текст джерелаWu, Cheng-Yu, and 吳昌瑀. "Effect of wick evaporation area on thermal performance for loop heat pipe with flat evaporator." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/09314070664185237929.
Повний текст джерела中華科技大學
飛機系統工程研究所在職專班
102
This study investigates the effects of increasing the evaporating area of wick in a Flat Loop Heat Pipe(FLHP). This work attempts to improve the performance of the FLHP by increasing the number of grooves and thereby the surface area of the wick. The number of grooves is increased from 0%(grooves 8) to 90%(grooves 16). Production results are limited that we cannot be successfully produced the wick structure of 16 grooves, so the thermal permormance of the test and wick parameters of testing only for grooves 8~14. Experimental results show that increasing the number of grooves not only increases the surface area of the wick but also enhances FLHP performance. When the evaporating surface area increases by 45%(grooves 12),which corresponds to increasing the number of grooves 8 to 14, We can get most of the heat transfer performance, also the heat transfer capacity increases to 260W and enhance the heat transfer performance about 30%. Wick permeability:13-20×〖10〗^(-13)(m^2)、pore size:3.1~3.7(μm)、porosity:60~66%. The rate of change of the wick is tiny,also good production within the range suggested in the literature. Produced by the simplicity and success rate, we recommend that the evaporation area is increased by 45%(grooves 12),thermal resistance is reduced to 0.2℃/W, The heat transfer raised to 260W, enhancethe heat transfer performance about 30%.
YU, YEN-YI, and 游晏宜. "Design and discuss of the flat tubes and parallel flow evaporator." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/t8c67v.
Повний текст джерела國立中央大學
機械工程研究所
94
This project will discuss the flat tubes and parallel flow heat exchangers air-conditioner. The traditional round tube evaporator and condenser in an air-conditioner will be replaced by flat tube parallel flow evaporator. In this project not only design the flat tube parallel flow evaporator but also test the flat tube evaporator. The compressor, expansion valve and other components in the air-conditioner will also be modified according to the changes of heat transfer and pressure loss of the heat exchangers. This project will be performed by the cooperation with the TECO Electric and Machinery Co., Ltd. The ME department will design and test the flat tube evaporator and condenser and the TECO will take charge of other components. A compact, low noise and high performance air-conditioner will be developed in this project.
GUN-NING, KUO, and 郭君寧. "Thermal Performance of a Loop Heat Pipe with a Flat Evaporator." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/38977099709502269606.
Повний текст джерела國立臺灣科技大學
機械工程系
92
The heat transfer characteristics of a loop heat pipe with flat-shaped evaporator was studied experimentally . Thermocouples were used to measure temperatures along the loop. Trends of steady-state operating temperature are presented and explained for two different tilt angles of the loop. Temperature hysteresis and low-power start-up problems were observed and discussed. The maximum heat transport capacity was up to 100W with a thermal resistance of 0.212℃/W and an operating temperature around 60℃.
Chen, Jia-Ruei, and 陳嘉瑞. "Investigates the application of PTFE wicks to Loop Heat Pipe with flat evaporator." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/28403727381712240959.
Повний текст джерелаChang, Chia-Wei, and 張家瑋. "Visualization and Measurement for Sintered-Wick Evaporator in an Operating Flat-Plate Heat Pipe." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/48869875797606783280.
Повний текст джерелаLai, Shih-Ru, and 賴世儒. "Investigation of the Effect of Heat Leak in Loop Heat Pipes with Flat Evaporator." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/48037703193312162536.
Повний текст джерела國立臺灣大學
機械工程學研究所
95
Loop heat pipes (LHPs), which are generally and widely used with cylindrical evaporators, have a great potential for applications of spacecrafts and electronic cooling due to the advantages of high transfer capacity, low thermal resistance and long transport distances. However, the cylindrical evaporators of loop heat pipes cannot work on a flat thermo-contact surface without saddle. The saddle not only creates an extra thermal resistance but also makes evaporators less isothermal. To avoid the above disadvantages, we adopt the flat evaporators of loop heat pipes. According to the literature, however, the heat leak problem is more serious in the flat evaporators than the cylindrical evaporators. This problem also makes the thermal resistance of flat evaporators higher. Hence this study tries to solve the difficulties and provides two solutions. The first method is to increase the thermal resistance of the wick by raising the wick thickness. The second method, we design a double-decked wick, which is composed of the primary wick sintered with metal powder and the secondary wick made of the low thermal conductivity polymer. The material wick generates higher capillary forces and the polymer has lower thermal conductivity. Such design can ease the heat leak problem. The results show that both methods can ease heat leak problem. When primary wick thickness of double-decked wick is 4 mm, the temperature of the evaporators is less than 100oC and the sink temperature is at 30oC. The maximum heat capacity increases from 40W to 180W. In addition, the thermal resistance decreases from 0.69 K/W to 0.38 K/W
Basha, Mulla Saleem. "Heat Transfer and Visualization Studies in the Evaporator of a Flat Loop Heat pipe." Thesis, 2020. https://etd.iisc.ac.in/handle/2005/4493.
Повний текст джерелаWei, Kai-chin, and 魏愷進. "Experimental Investigation on the Thermal Performance of a Loop Heat Pipe with a Flat Evaporator." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/07098029413457812793.
Повний текст джерела國立臺灣科技大學
機械工程系
93
In this study, a two-phase closed loop cooling system aimed to be used in electronic system is designed and tested. The cooling system consists of a flat evaporator with wick structure inside, a tube-and-fin condenser, and two connecting tubes between evaporator and condenser. The connecting tubes are transparent silicon tubes which can be used for flow pattern observation. Water is used as the working fluid. The cooling system is charactered by a parametric study which determined the effect of charging capacity, the tilt angle of the system on the thermal performance of the closed loop. Experimental data show that the system has optimal performance under vertical operating condition with 22cc water charging capacity. The thermal resistance of the system is around 0.384℃/W under this configuration.
林宇中. "Visualization and Measurement for Evaporator in Operating Flat-Plate Heat Pipes-Different Working Fluids and Wettabilities." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/56220279196942776357.
Повний текст джерелаLu, Chien-Ming, and 盧建銘. "Effect of Sintering Rising Temperature Slope in Wick Manufactured for Loop Heat Pipe with Flat Evaporator." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/70701179540159460535.
Повний текст джерела中華科技大學
飛機系統工程研究所在職專班
102
Loop heat pipe (LHP), which are generally and widely used with cylindrical evaporators, have a great potential for applications of spacecrafts and electronic cooling due to the advantages of high transfer capacity, low thermal resistance and long transport distances. However, the cylindrical evaporators of loop heat pipes cannot work on a flat thermo-contact surface without saddle. The saddle not only creates an extra thermal resistance but also makes evaporators less isothermal. To avoid the above disadvantages, we adopt the flat evaporators of loop heat pipe. This investigation examines the effect of the effect of the sintering temperature curve in manufacturing nickel powder capillary structure (wick) for a loop heat pipe (LHP) with flat evaporator. The sintering temperature curve is composed of three regions: a region of increasing temperature, a region of constant temperature, and a region of decreasing temperature. The most important region is the increasing temperature region, as the rate of temperature increase directly affects the performance of the wick.When the slope of the region of increasing temperature is 0.8 (equivalent to 8℃/min), the structure of the manufactured wick is complete, with the best heat transfer performance result. Experimental resultsshowed that the optimal heat transfer performance is 160W, the minimal total thermal resistance is approximately 0.43℃/W, and the heat flux is 17W/cm2; the optimal wick manufactured has an effective pore radius of 5.2 μm, a permeability of 8.5×10-13m2, and a porosity of 64%.
Lo, Kuei-Chi, and 羅貴淇. "Effect of Sintering Temperature and Time in Nickel Wick for Loop Heat Pipe with Flat Evaporator." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/73084329970070502961.
Повний текст джерела中華科技大學
飛機系統工程研究所在職專班
102
This paper specifically addresses the effect of changing the constant temperature region of the sintering temperature curve in manufacturing nickel powder capillary structure (wick) on the performance of a flat loop heat pipe (FLHP). The sintering temperature curve is composed of three regions: a region of increasing temperature, a region of constant temperature, and a region of decreasing temperature, with the sintering time and temperature in the region of constant temperature having significant effect on the permeability of the wick. In this study, for wick manufacturing the temperatures in this region tested range from 550°C to 650°C and the time from 30 minutes to 60 minutes. The properties and internal parameters of the wick are measured, and the wick is placed into FLHP for performance testing. Experimental results show that at sintering temperature of 550°C and lasting about 45 minutes, maximum heat load is 200W, minimum thermal resistance is 0.32°C/W, permeability is 1.2×〖10〗^(-12) m^2, porosity is 66%, effective porosity is 3.8 μm, and heat flux is around 21W/cm2; related literatures have only reported maximum heat load increase of 25%.
Wu, Wei-Ting, and 吳韋廷. "Heat Transfer Enhancement of Loop Heat Pipe with Flat Plate Evaporator using 2-Butanol Aqueous Solution." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/r7gj95.
Повний текст джерела中華科技大學
飛機系統工程研究所
106
Under the rapid development of the electronics, consumer electronic product, the demand of cooling increases with the raises of power density. Loop Heat Pipe (LHP) system often characterized by high heat transfer capacity and long transport distancing. It shows great potential for electronic cooling. The objective of this study is the application of self-rewetting fluid as the working fluid on Loop Heat Pipe with flat evaporators (FLHP) to increases the heat transfer performance. Use the 2-butanol aqueous solution as the working fluid on FLHP, with nickel as the capillary structure material. Self-rewetting fluid shows better wettability compared with pure water. At a certain temperature, a self-rewetting fluid, contrary to common fluids, has the ability to reverse its surface tension’s trend, inducing colder fluid to flow to the heated surface and delaying the occurrence of dry-out in FLHP, it is advantageous to use self-rewetting fluid as working fluid on heat-transfer devices. Heat transfer performance test results shows that water and 2-Butanol(20wt%) aqueous solution in nickel wick FLHP, the maximum heat load from 150W to 425W, can improve heat transfer performance about 180%, the thermal resistance decreased from 1.2℃/W to 0.61℃/W, the heating area is 961mm2 and the maximum heat flux from 15W/cm2 to 41W/cm2.
YEN, SHIH-HSUAN, and 顏士軒. "Study of Self-Rewetting Fluid Applied to PTFE Wick structure of Loop Heat Pipe with flat evaporator." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/00634478782462936917.
Повний текст джерела中華科技大學
飛機系統工程研究所
104
This study investigated the application of self-rewetting fluid to Nickel and PTFE wick structure of Loop Heat Pipe with flat evaporators (FLHP) and its effect on the heat transfer performance of FLHP. PTFE wick structure can prevent FLHP heat leakage problem, however, PTFE material with strong hydrophobic nature, cannot use the water as the working fluid. Therefore, this study attempts to use Self-rewetting fluid's good wettability to overcome the PTFE wick's hydrophobicity. At a certain temperature, a self-rewetting fluid, contrary to common newtonian fluids, has the ability to reverse its surface tension's trend, inducing colder fluid to flow to the heated surface and delaying the occurrence of dry-out in FLHP during operation. Thus, this study focused on a few self-rewetting fluids; the surface tensions of these fluids were measured, and then it was applied to FLHP as working fluid to investigate its effect on the heat transfer performance. Heat transfer performance test results shows that DI water and 1-Butanol;1-Heptanol aqueous solution in nickel wick’s FLHP, the maximum heat load can be up to 280W,Compared to DI water's 140W can improve heat transfer performance about 70 to 100% . DI water and 1-Butanol;1-Heptanol aqueous solution in PTFE wick's FLHP, the maximum heat load can be up to 240W,Compared to DI water's 40W can improve heat transfer performance about 300 to 500% .
Liou, Jhan-Hong, and 劉展宏. "Visualization and Measurement for Evaporator of Different Sintered-Wicks and Working Fluids in Operating Flat-Plate Heat Pipes." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/50107468376505893258.
Повний текст джерелаDONG, HONG-WEI, and 董宏威. "Research on the Liquid-side Grooves of Wick in Loop Heat Pipe With Card-type of Flat Evaporator." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/9r38hn.
Повний текст джерела中華科技大學
飛機系統工程研究所在職專班
106
In this study, we tried to design and make liquid-side grooves on the surface of the wick next to the compensation chamber, which is in the card-type flat evaporator. By this, the absorbing surface area of working fluid increased and thereby decreased the flow resistance in loop heat pipe with card-type of flat evaporator. We used PTFE as material of wick, because of its low thermal conductivity, and acetone as working-fluid. Results indicated that heat transfer performance increases in the wick structure with liquid-side grooves , of which the critical heat load(dry-out heat load)reached 175W, the thermal resistance was 0.77℃/W and the heat flux reached 28W/cm². Comparing with the structure without liquid-side grooves under 100℃, the typical operating temperature of electronic devices, our design increased the heat load about 50%. As the reason, wick structure with liquid-side grooves has a great potential to improve the performance of loop heat pipe.
LO, CHUN-CHENG, and 羅浚誠. "Study of Performance Enhancement with the Double-Side Grooves Wick Applied to Loop Heat Pipe with Card-Type of Flat Evaporator." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/6pcxa4.
Повний текст джерела中華科技大學
飛機系統工程研究所
107
This study is to manufacture more liquid groove on the wick structure and apply to the card-type flat loop heat pipe. The purpose is to enhance the heat transfer of performance. Besides the single side vapor groove and 5 liquid grooves designed on the wick structure before. In order to increase the liquid receiving surface absorption and in a limited space condition, we manufacture the 10 liquid grooves to make the working fluid easier to absorb. This design has the effect of reducing the flow resistance and increasing the liquid receiving surface absorption, and also helps to enhance the heat dissipation effect. In this study, we use a low thermal conductivity of Teflon (polytetrafluoroethylene, PTFE) as the material of the wick. Due to the hydrophobic nature of PTFE, this study uses acetone with a lower operating temperature and good compatibility as the working fluid, and make it simply absorbs to the wick. We also hope it can exert phase change effect when the system is operating, thereby improving the heat transfer performance in card-type flat loop heat pipe. The experimental results show that the maximum heat transfer capacity of the 10 liquid grooves of wick is about 300W, and the lowest thermal resistance value is about 0.598°C/W, which can reach the heat flux to 44.4W/cm2,and if the evaporator wall set about 100°C of limitation, the heat load is more than 92% to the single side vapor groove of wick, and it also more than 67% to the 5 liquid grooves of wick. It can be proved that the 10 liquid grooves of wick has the best heat transfer performance no matter to the single vapor groove or 5 liquid grooves of wick in the card-type flat loop heat pipe.
王維文. "Experimental investigation of R-22 evaporation inside aluminum flat tubes." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/88253181223435959898.
Повний текст джерелаChao, Chi, and 趙淇. "Evaporation Resistance of Flat Heat Pipe Having Metallic Mesh Wick." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/44230452291185835598.
Повний текст джерелаChu, Yi-Ming, and 褚伊銘. "Study on the Performance of flat Loop Heat Pipe in the Wick of Compensation Chamber and Evaporation Zone." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/59a75e.
Повний текст джерела國立臺北科技大學
機電整合研究所
98
Loop Heat Pipe is a kind of heat pipe with both vapor chamber based on the theory of two-phase change thermal conductivity of the passive cooling system. Compared to the conventional heat pipe, loop heat pipe has a high heat transfer capacity, transmission distance of a long and low thermal resistance performance in cooling, space technology or military technology and other thermal applications. The flat loop heat heating element can be placed on the heat source directly without using saddle. During the startup process, the working fluid in the system will be distributed and phase transition including evaporation, condensation and boiling will occur, leading to the thermal status for each component unstable. In addition, boiling bubbles and thermal leakage also influence the system stability. Therefore, the start up and stable operation for the loop heat pipe is the aim to investigate in various research fields. In this study, two different sizes, different material powder were used. The wick structure of flat loop heat pipe can be fabricated to green tape with sinter process by using doctor blade casting. The first part, the sintered 400 mesh copper powders have higher capillarity and the better the heat transfer rate. In secondary part, 150 mesh nickel powders, have good permeability and lower capillarity to resist heat leaking to compensation chamber. The green tape made by doctor blade casting can be sintered to chamber of flat loop heat pipe for single time. It can decrease the error during the manufacturing. In the experiment, various water contents of 6.2g, 8.6g and 10.6g were injected to measure the performance. According to the characterization, the flat loop heat pipe has no obvious thermal oscillation and performs freely during the operation. The results show that the 6.2g water content injection has the lowest heat resistance of 0.21 ℃ / W. In addition, the compensation chamber for additional cooling can increase the operation stability and decrease the system thermal resistance.
Pei, Shan-Yung, and 裴善永. "A Study of Convective Evaporation in a One-side Heated Flat Channel of a Liquid Cooling Device for Chips." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/7w9vw4.
Повний текст джерела國立臺北科技大學
能源與冷凍空調工程系碩士班
95
This study investigates the influence of the heat flux and mass velocity on convective heat transfer performance of two fluids (water and FC-72) in a rectangular channel subjected to one side heating. The fluid passes through a rectangular channel, having either a smooth surface or a pin fin surface, with a flow rate from 80ml/min to 960ml/min. The inlet fluid temperature is maintained at 30oC. The cross section of the test channel is 20mm wide and 2 mm high. The total length of the test channel is 113 mm, with a heated length of 25mm. The heat flux varies between 32 and 98 W/cm^2. A high speed camera system is used to record the phenomenon of flow boiling. The observation is compared with experimental data and found that the flow patterns depend on heat flux and flow rate. For water, single phase convection is the dominant heat transfer mechanism during the present tests except for the flow rate less than 160 ml/min and heat flux > 50 W/cm^2. At a fixed flow rate, the pin fin surface yields up to 40% higher heat transfer coefficient and greater critical heat flux than those of a smooth surface. The pin fin surfaces and the smooth surface yield similar performance in FC-72, where convective boiling is the main heat transfer mode. In the present FC-72 tests, bubbly flow is the dominant flow regime. Plug flow and churn flow occur at high heat fluxes. The convective heat transfer coefficient of FC-72 is greater than water at low flow rate (80~ 160 ml/min) and heat flux = 15 ~ 35 W/cm^2, where the thermal resistance is about 0.22 K/W. However, the convection performance of water is superior to FC-72 at high flow rates.
Ruben, Aza-Gnandji Cocou Davis. "Salinity of irrigation water in the Philippi farming area of the cape flats, Cape Town, South Africa." Thesis, 2011. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_8633_1365586459.
Повний текст джерелаThis research investigated the nature, source and the spatial variation of the salinity of the water used for irrigation in the urban farming area of Philippi, which lies in the Cape Flats region of the Cape Town Metropolitan Area, South Africa. The irrigation water is mainly drawn from the Cape Flats aquifer, and pumped into ponds for eventual crop irrigation. Water samples were collected in summer and in winter from fifteen selected sites using standard water sampling procedures. Each site consisted of one borehole and one pond. The samples were routinely analyzed for salinity levels, and concentrations of major and minor ions. From the same boreholes and ponds, water was sampled in summer for isotope analysis to assess effects of evaporation on the water quality and salinity. Descriptive statistics were used to display the variation in range of specific ions in order to compare them with the recommended ranges. Geographical Information Systems analysis described the spatial distribution of the salinity across the study area, and hydrogeochemical analysis characterized the various waters and detected similarities between the water samples in the study area and other waters found in the Cape Flats region. In addition, the US salinity diagram classification of irrigation water developed by Richards (1954) was used to assess the current suitability of groundwater and pond water samples collected during the entire sampling period for irrigation activities. The research indicated that the concentrations of some ions such as chloride, nitrate, potassium and sodium exceeded in places in the study area, the target range values set by the Department of Water Affairs and Forestry (DWAF, 1996) and the Food and Agriculture Organization (Ayers and Westcot, 1985). It revealed that borehole and pond water were mostly brackish across the area regarding their total dissolved salts content, and fresh water was only found in the middle part of the study area. The research found that sea water does not intrude into the aquifer of the study area, and the accumulation of salts in groundwater and soil in the study area is mainly due to the agricultural activities and partially due to the natural movement of water through the geological formation of the Cape Flats region. The conceptual model of the occurrence of the salinization process supported these findings. From this investigation it is understood that the groundwater and pond water in the study area were generally suitable for irrigation purposes but they have to be used with caution as the vegetables are classified as sensitive and moderately sensitive to salt according to DWAF Irrigation water guidelines (1996). The quality of these waters was mainly affected by the land use activities.