Wick Material Research Articles

Unveiling the mythical candles

Candles were invented 5000 years ago and are still widely adopted in numberless occasions to illuminate the buildings and to create a romantic environment due to their warm and pleasant sensation giving emission, which helps people relax. Nevertheless, some myths remain unsolved regarding their color, color temperature, power efficiency, their effects on human health, and fire hazard. We have hence investigated these based on a paraffin wax candle. As learned experimentally, the flickering candle flame shows on average an orange-red color with Commission Internationale de l'Eclairage 1931 coordinates of (0.55, 0.41) and a 1819 K color temperature through observation behind a tracing paper. Although the luminous intensity may vary from 1.0 to 2.2 cd, the luminous efficacies of studied candles fall around 0.27 l m/W. From a retina protection perspective, candlelight is presumably 2 times safer than the typical incandescent bulb or warm-white compact fluorescent lamp (CFL), and 3 times safer than the warm-white light-emitting diode (LED). Correspondingly, if used at night, it is about 2 times better for melatonin secretion than the incandescent bulb or warm-white LED, and 3 times better than the warm-white CFL. However, surprisingly, candlelight-style organic light-emitting diode (OLED) is healthier than real candlelight: from retina protection and melatonin secretion perspective, the candlelight style OLED is about 3 times safer and 2 times better than candlelight, respectively. While the luminous intensity may sensitively vary with the variation of wax as well as wick material and size, the candle color and color temperature barely alter with different compositions.

Experimental Research on the Behaviour of Heat Pipe Using Graphene Oxide as Working Fluid

The liberation of heat from the electronic devices used in the industries, refrigeration and etc. is main concern today. The temperature of the planet earth is being increasing day by day, the generation of heat by the manufacturing industries should be reduced using innovative techniques. Generally a heat exchangers were used to reduce it. In this study, graphene oxide employed as as working fluid to determine the effective thermal conductivity. The working fluid graphene oxide plays vital role in dissipation of heat from the evaporation zone to condensed zone. The experiment setup was done with about 19.1 mm and 21 mm inner and outer diameter, respectively. The length of the heat pipe is 600 mm. The wick material was made up of brass. We observed that the graphene oxide improved thew efficieny by using as working fluid.

High efficient solar evaporation by airing multifunctional textile

Solar evaporation is important for many applications such as desalination, power generation and industrial drying. Recently, some studies on evaporation reported obtaining high energy efficiency and evaporation rate, which are based on floating evaporation setup (FES) with nanomaterials. Here, a new cheap and simple setup is proposed, named as airing evaporation setup (AES). Compared to FES, there are four advantages of AES: a better thermal design, a higher energy efficiency, a higher material utilization ratio, and multi-function. It shows that the energy efficiency of AES reaches up to 87% under 1 kW/m2 of solar irradiation, which is 14% higher than that of FES. Meanwhile, the total evaporation rate of AES is about 20% higher than that of FES. The theoretical analysis reveals that the main reason for a better performance of AES is the increasing evaporation area. More interestingly, AES could be used for designing portable systems due to its simplicity and flexibility. Furthermore, it is shown that AES and the corresponding wick material can be used in solar desalination, textile quick-drying and warm-keeping.

Electrically Driven Interfacial Evaporation for High-Efficiency Steam Generation and Sterilization.

Electrically driven steam generation is a critical process for many heating-related applications such as sterilization and food processing. Current systems, which rely on heating up the bulk water to generate steam, face the dilemma in achieving a large evaporation flux and fast thermal response. Herein, we report a self-floating electrically driven interfacial evaporator for fast high-efficiency steam generation independent of the amount of loaded bulk water in the system. Through localized heating of the wicked water at the air–water interface, the evaporator has achieved an electrical-to-steam energy conversion efficiency of ∼90% at a heating power density of 10 kW/m2 and a fast thermal response of 20 s. The interfacial evaporation design not only achieves a high evaporation efficiency within a broad range of heating power densities by using different wicking materials, but also enables attaining a high evaporation temperature under low heating power densities by tuning the ratio of the vapor outlet area and the evaporation surface area. By integrating an interfacial evaporator within a sanitizer, the resultant system has demonstrated a faster steam temperature rise and superior steam sterilization performance than the commercial bulk heating-based approach.

Efficiency enhancement on the solar steam generation by wick materials with wrapped graphene nanoparticles

Solar steam generation technology can utilize abundant and renewable solar energy for many applications. In this work, we proposed a low-cost high-efficiency solar steam generator by using wick materials with wrapped graphene nanoparticles, and the energy efficiency can reaches up to 80%. Instead of traditional smearing method, the chemical wrapping method was used for better coating the graphene nanoparticles on the wick materials. Through the SEM morphological results, the graphene nanoparticles are shown to be evenly wrapped across the fibres of the wick material, which have better dispersity and stability. The evaporation rate, instantaneous energy efficiency and the solar absorptivity of three wick materials with/without nanoparticles under different conditions were compared and analyzed. Among the three different wick materials, the fine fluffy cloth can provide more three-dimensional contact area for wrapping graphene nanoparticles and thus contribute to better evaporation. Additionally, the influence of two different reduction methods and different concentrations of graphene oxide solution on the energy efficiency was also analyzed. Our work offers a simple and effective way of using nanotechnology in practical application for better solar-to-heat conversion.

Experimental investigation of single slope solar still using different wick materials: a comparative study

Solar still play an important role in mitigating potable water scarcity mainly in developing countries because of its low-cost and easy design. One major concern regarding solar still is the low productivity. Using a wick in still basin decreases active water depth and increases the evaporation rate of basin water. In the present work, a comparative study of single slope solar still using different wick materials is performed. Bamboo cotton, jute, wool, and cotton are used as wick materials. To carry out experiments, two single slope solar stills of similar dimensions are designed and constructed. Wick is placed over the rectangular shaped fins installed in the still basin. The experiments are conducted for 25 days and data collected on the clearest sunshine days are presented in this work. Water depth is kept constant at 1 cm throughout the experiments. Experimental results showed that maximum still productivity and efficiency is obtained using bamboo cotton wick as 3.03 l/m2day and 34.5% respectively. This is 16.9%, 20.7%, 37.8% and 51.9% higher than jute, cotton and wool wick and conventional still. It is evident from the experimental results that bamboo cotton is the most suitable wick material in comparison to others.

Solar vapor generation under concentration illumination using carbon black

Begin Solar vapor age speaks to a promising and earth kind-hearted strategy for water cleaning and desalination. Ordinary sun oriented steam age methods normally have moderately low proficiency because of mass warming of the completely fluid volume. Here, a productive methodology dependent on the warmth confinement. Utilizing minimal effort materials, i.e., carbon dark (powder), A wick material was utilized to transport the water from the mass water to the dissipating surface extended polystyrene froth was utilized to warm protection between the surface fluid and the mass volume of the water. a record warm productivity of ≍78.3% is acquired under 7 sun comparing to the dissipation rate of 1.105 kg (m2 h)−1. As indicated by the outcomes, the carbon molecule fixation influences the proficiency. This framework can give a way to deal with people to cleanse water for individual needs, which is especially reasonable for areas with no entrance to power.

Oil stove modification to get optimum performance on jatropha oil usage

This research is based on the idea to combine efforts on promoting jatropha oil as one of renewable and green energy resources, and efforts to help “house hold oil stove industries” continuing their production even-though more people change kerosene to LPG as their main fuel for cooking. Regarding the idea, this research aims to modify oil stove which has been sold in the market, which was designed for kerosene fuel, to be able to use with jatropha oil and other oil as its fuel in the good performance. Two approach methods based on the physical oil characteristic has been done. They were modification of wick material, and “oil pre-heating system” implementation. The result shows that no wick material having good performance when implemented for jatropha oil usage due to its high viscosity. Original wick has best performance compare to modified wicks. By using original wick, implementation of oil pre heating system has been successfully increasing fuel rate combustion from 0.43 kg/h to 0.63 kg/h, and increasing the total system efficiency from 9.54% to 16.1%.

Increased Production of Mustard (Brassica juncea L.) with Application Capillary-Irrigation System

Increased Production of Mustard (Brassica juncea L.) with Application Capillary-Irrigation System. Application of capillary irrigation system on mustard is expected to increase the crop productivity. The aims of this study was to calculate the use of water of mustard with application capillary irrigation using wick and flanneland to determine the best combination of irrigation capillary tools of capillarity system. The design of this study used two factors and three replications. The first factor was wick materials (S), consistings two level: the flannel wick (S1), and stove wick (S2). The second factor was the dosage sawdust (M), consists two level: 0 % of sawdust (M1), and 50 % of sawdust (M2).The research results showed that total water use of M1S1 is 169.7 ml and M1S2 is 107,91 ml, M2S1 is 198.4 ml, and M2S2 is 151.76 ml. The best combination of this research obtain on M2S1, the second cultivating media, the soil by using soil with silty clay loamtexture which mixed50 % of sawdust and the wick of flannel.

Design of an Area-Scalable Two-Layer Evaporator Wick for High-Heat-Flux Vapor Chambers

A hybrid two-layer evaporator wick is proposed for passive, high-heat-flux dissipation over large areas using a vapor chamber heat spreader. For such applications, the evaporator wick layer must be designed to simultaneously minimize the device temperature rise and minimize the flow resistance to a capillary feeding of the wick. This requires a strategy that exploits the benefits of a thin wick for reduced thermal resistance and a thick wick for liquid feeding. In the present design, a thick cap layer of wick material evenly routes liquid to a thin, low-thermal-resistance base layer through an array of vertical liquid-feeding posts. This two-layer structure decouples the functions of liquid resupply (cap layer) and capillary-fed boiling heat transfer (base layer), making the design scalable to heat input areas of ~1 cm2 for operation at 1 kW/cm2. A reduced-order model is developed to demonstrate the potential performance of a vapor chamber incorporating such a two-layer evaporator wick design. The model comprises simplified hydraulic and thermal resistance networks for predicting the capillary-limited maximum heat flux and the overall thermal resistance, respectively. The reduced-order model is validated against a higher fidelity numerical model and then used to analyze the performance of the vapor chamber with varying two-layer wick geometric feature sizes. The two-layer wick design is found to sustain liquid feeding at higher heat fluxes, without reaching the capillary limit, compared to single-layer evaporator wick designs.

Capillary Wicking in Hierarchically Textured Copper Nanowire Arrays.

Capillary wicking through homogeneous porous media remains challenging to simultaneously optimize due to the unique transport phenomena that occur at different length scales. This challenge may be overcome by introducing hierarchical porous media, which combine tailored morphologies across multiple length scales to design for the individual transport mechanisms. Here, we fabricate hierarchical nanowire arrays consisting of vertically aligned copper nanowires (∼100 to 1000 nm length scale) decorated with dense copper oxide nanostructures (∼10 to 100 nm length scale) to create unique property sets that include a large specific surface area, high rates of fluid delivery, and the structural flexibility of vertical arrays. These hierarchical nanowire arrays possess enhanced capillary wicking ( K/ Reff = 0.004-0.023 μm) by utilizing hemispreading and are advantageous as evaporation surfaces. With the advent and acceleration of flexible electronics technologies, we measure the capillary properties of our freestanding hierarchical nanowire arrays installed on curved surfaces and observe comparable fluid delivery to flat arrays, showing the difference of 10-20%. The degree of effective inter-nanowire pore and porosity is shown to govern the capillary performance parameters, thereby this study provides the design strategy for capillary wicking materials with unique and tailored combinations of thermofluidic properties.

Performance of single-slope double-basin solar stills with small pile of wick materials

The performance of single-slope double-basin solar stills was evaluated with the use of small pile of wick materials in lower basin of stills. For the study, two similar single-slope double-basin solar stills were developed with the small pile of two different wick materials namely jute cloth and black cotton cloth. The experiments were conducted for the two different water depths such as 0.01 m and 0.02 m in lower basin under the environmental situation of Valsad, Gujarat (20.61°N, 72.91°E) India. From the results of experiments, the enhancement of 18.03% and 21.46% in yield was obtained at 0.01 m and 0.02 m water depth for the still with small pile of jute cloth compared to the still with small pile of black cotton cloth. From the experiment, it has been observed that the still with small pile of jute cloth achieved the overall higher productivity compared to the still with small pile of black cotton cloth.

Development of lotus-type porous material for heat pipe application using centrifugal slip casting process

Heat pipe is a heat conductor which has a large conduction capacity using a special fluid-filled pipe as a conductor of heat from the hot end (evaporator) to the cold end (condenser) used for thermal management. In the heat pipe, there is a sintered wick which transfers refrigerant fluid from condenser to evaporator. The objective of this research is to improve capillary performance by making a straight pore called as lotus-type porous material (LTP) using centrifugal slip casting technique. Copper powder is used as wick materials due to its high thermal conductivity. A starch solution is used as binder material to make the copper slurry. Nylon wire is applied as straight pore mold. Freeze drying is applied to curing and demolding. Vacuum sintering is conducted to increase metallurgical bonding between the particle. The results show that centrifugal casting machine is capable to make a wick with LTP structure. On the performance department, capillary pumping is affected by rotation speed, powder size, and powder loading. The optimum parameters were copper powder with 260.54 μm powder size, 50% Powder Loading with 688 rpm rotation speed. The LTP wick is proved to have a higher capillary pumping capacity compared to the conventional wick. Further work is necessary to verify the performance of LTP wick in the heat pipe.

Condensation Rate Enhancement of the Inclined Condenser in the Solar Still Connected With a Solar Water Heater

One method to increase the fresh water productivity of the basin type stills is to increase the condensation rate of their condensing surfaces. A basin type still with an aluminum condenser was fabricated and tested in the Department of Mechanical Engineering at Texas Tech University. To increase the condensation rate the outer surface of the condenser was cooled with cooling water at different flow rates with and without woven jute material above it. For the same reason, cotton wick material was installed inside the basin of the still. It was found that the higher the flow rates of the cooling water across the condenser, the greater the condensation rate. Installation of cotton wick material inside the basin of the still and using jute material above the outer side of the condenser also caused an increase in the condensation rate thereby an increase in fresh water productivity of the still. Further, it was found that the maximum fresh water productivity was achieved when both the jute and the wick materials were installed during the experiment and when the condenser was cooled by water at 10 L/hr flow rate.

Topology optimization of the wick geometry in a flat plate heat pipe

In the present study, a topology optimization approach is proposed to determine an optimal geometry of a wick sintered inside a flat plate heat pipe. Total thickness of the heat pipe is assumed as fixed, and thus the task involves redistributing the wick material and selecting the internal shape of the vapor core to provide a minimum power dissipation in the liquid flow and minimum total pressure drop in the entire heat pipe. Constraints are used for the maximum volume of the wick and maximum allowable temperature of the heat pipe wall. With respect to the preliminary assessments, the simulations are realized based on simplified 2D steady state thermal and hydrodynamic models assuming constant temperature and laminar flow in the vapor core and Darcy’s law for the liquid flow through the porous wick. Optimization results are presented for rectangular flat heat pipes with different lengths and thicknesses. Optimal placement of the wick columns and grooves are obtained by using the proposed topology optimization scheme. The results indicate that the use of the wicks of optimal shape increases the operating performance of flat heat pipes and especially increases their heat transfer capability up to twice that of heat pipes with flat wicks of constant thickness.

Productivity enhancement of solar still by PCM and Nanoparticles miscellaneous basin absorbing materials

Belongings of incorporating (Al2O3) Nanoparticles of wick materials in the solar still of a PCM charity in the basin for TES organization have been probed in this study. It is an innovative organization of techniques by a drip button to decant saline water drop by drop on absorbing materials in the basin. It (summer and winter) has been established with the dripping of saline water on altered absorbing materials like CW, FWCW, JW and FWJW as the basin liner. Diurnal variations of drip button temperature, Tg, Tb, Tw and mass of the output have been verified. Vitality equilibrium equations for the moist air inside the still, glass cover and wick material have been solved to get the analytical expressions for the instantaneous efficiency of the anticipated structure. The numerical calculations have been authenticated with the experimental annotations for a (S & W) few typical days from January 2016 to January 2017. With the heat extraction performance, the yield of wick materials with a single basin solar still by a PCM and Nanoparticles (S & W) as FWCW is 7.460 & 4.120kg/m2day, respectively. The theoretical and experimental results have been substantiated a good covenant structure with the tiniest inaccuracy.

Enhancing wicking microflows in metallic foams

Metallic foams with high pore density have the potential to be used as highly wicking materials due to the improved capillarity caused by the high porosity and interconnected microchannels. The challenge for using them in their original state lies in their relatively large contact angle. To overcome this, a chemical blackening process for creating a superhydrophilic surface on copper foams is developed. The treatment resulted in a reduction of contact angle from about 91° to almost 0°, indicating a significantly improved wettability. The wicking capacity is further enhanced by controlling the porosity. Rate-of-rise experiments on the treated metal foams with different porosity were conducted. A wicking height of 140 mm in the treated metal foams was achieved compared to no wicking before treatment. A 3-month stability test in a vacuum showed that the contact angle and the wicking performance of the treated copper samples remained unchanged.

A New Approach for Thermo-Fluid Behavior through Porous Layer of Heat Pipes

This paper developed a new mathematical model to investigate the heat transfer as well as wick thickness of a heat pipe. The model was set up by conservative equations of continuity, momentum and energy in the thermal boundary layer. Using the similarity variable, the governing equations have been changed to a set of ordinary differential equations and they were solved numerically by the forth order Runge-Kutta method. The flow variables such as velocity components, wick thickness and Nusselt number were obtained. The results show that the Nusselt number is proportional to the root square root of the Darcy-modified Rayleigh number and that the distance from the edge of the condenser surface. Furthermore, the thickness of the wick material depends on the Jakob number and proportional to the heat transfer between the wall and the liquid film.

The mass transfer coefficient assessment and productivity enhancement of a vertical tubular solar brackish water still

This paper presents an experimental investigation of a single-effect vertical tubular solar brackish water desalination device, with an aim to determine the mass transfer coefficient and its enhancement. The device consists of two closely spaced concentric pipes. The outside of the inner pipe is covered with a wicking material and wetted with hot brackish water. The water vapor evaporated from the wicking material condenses on the inside of the outer pipe. The measured productivity and temperatures at various points are given for different wicking materials thickness, water flow rates and chamber pressure under the condition of given heating power. Mass transfer coefficients are calculated from the experimental results and then applied in the prediction of water productivity. The maximum discrepancy between the calculation yield and measurement yield is relatively small compared with previous study. In addition, it was found that the yield of the solar still is 23.9% higher when the chamber pressure is lower by 25kPa due to the enhanced mass transfer. Similar, doubling the ambient air velocity can increase the water yield by about 17.0%.

Experimental investigation of tilted wick solar still using fabrics

Solar still is the device for solar distillation, in which water is stagnated in a basin and it is covered with glass cover. Water when exposed to solar radiation, gets evaporated and condenses under the tapered glass surface. This process removes the temporary hardness in the water, but doesn’t alter the water taste. In the present work, tilted wick solar still with flat plate absorber have been fabricated and an analysis was made to review the effect of various wick material such as terrycloth, jute cloth, fur fabric and polyester cloth over the absorber plate which was inclined at 30°. In this type of stills, a huge quantity of water is not stagnated hence the vapour temperature inside the still is higher when compared to conventional stills. The experimental results show that the yield is maximum for fur fabric. Cost involved in production of water per litre in the still with respect to investment and other costs involved also presented in this article.