Acknowledgement This experiment was done as part of a week long undergraduate course on practical experimental methods, at the Copenhagen Conservation School. The heat flow from the hot plate is adjusted manually to hold the temperature exactly at ambient.
Kaisa left has just removed the damp cloth specimen from the warm plate and is putting it into a zip-lock PE bag for weighing. The temperature falls, as shown by the red temperature graph, so the cloth is behaving like an inefficient psychrometer, taking some heat by conduction from the metal plate which it rests on the experimental arrangement is shown in figures 4 and 5.
The full reportwith experimental details is in a pdf file. This is shown by the rise in temperature towards ambient, indicating a decreasing flow of energy needed to evaporate water, even though bound water requires more energy per molecule removed.
If the cloth temporarily loses water below this value, the cotton fibres will shrink temporarily. The second rectangle in the middle held the thermocouple to measure surface temperature and was also used to measure the change in length of the cloth during drying.
Energy has to be provided to change the water from liquid to vapour and an air stream is needed to remove the vapour. A pedantic note Psychrometry involves the properties of water and of air.
One need only drive a thermostat from a thin thermocouple lying just under the cloth, or ideally woven into it. One would expect the air flow rate to influence the drying rate. The cloth is placed on a metal surface designed to spread the heat flow from the underlying, smaller, laboratory hotplate.
It also turns out that the point of intersection of the arrow with the saturation vapour pressure line does not move as the air speed changes, over a wide range of speed.
This diagram is a portion of the vapour pressure diagram for water. At some temperature the heat loss through evaporation is exactly compensated by heat gain from the surroundings, by convection, conduction or radiation. We thank the staff of the school for lending various bits of equipment. A view from the top, showing the rectangle of cloth, about 5 x 10 cm, which was weighed to measure the drying rate, surrounded by the guard ring of cloth, which was also saturated at the beginning of each run.
The weighed portion of cloth is surrounded by a guard ring of cotton cloth which is also soaked at the beginning of each experimental run. The cloth moves to a lower temperature, expressed by the average molecular energy the dotted vertical line.
There is little convective air movement, because the temperature is the same as that of the room air though the acute reader will remark that the saturated air near the surface is slightly less dense than the dryer air in the Which fabric evaporates moisture the quickest essay.
Eventually the temperature will stabilise at some value below ambient which depends on the balance between the rate at which the water molecules emerge from the surface and the rate at which heat can reach the cloth to re-invigorate the remaining molecules in the liquid.
If they also slide past one another in the process, permanent shrinking or warping will occur. Only at the very end of each curve does drying of bound water within the fibre occur.
The drying rate of this cloth is shown by the lowest, steepest black curve in figure 3. The surface temperature then settled at The red curve shows the corresponding surface temperature attained by the cloth. Looking at the matter another way, the temperature dependent equilibrium between water at the cloth surface and vapour in the boundary layer of air is established very rapidly, compared with the rate at which the air stream can sweep the molecules away.
There is no chemical interaction between air molecules and water molecules. Only in the closing stages does the cotton release its internally bound water, at a decreasing rate.
Only molecules with a high kinetic energy, towards the right hand end of the graph, will escape from the liquid water surface, against the cohesive force that binds the molecules in liquid water. The effect of ventilation In the simplest drying arrangement, the cloth is flapping freely in the breeze, with only air to bring the heat.
The cloth may have left some water on the metal as it was removed for weighing during the first minutes of the experiment. In the experiment where the cloth is heated to ambient, the air is no longer tranferring heat, which is defined as energy transferred across a temperature gradient.
Figure 2 shows how the temperature and the water content of the air stream change as it passes over the cloth. This means that the rate of evaporation will be much lower, giving time for heat to migrate into the wet cloth from the surrounding air or other materials touching the cloth. The kinetic energy distribution of water molecules at two temperatures, shown with exaggerated separation to clarify the explanation.
Notice that the proportion of high energy molecules is much diminished, even though the temperature has only fallen five degrees. Henrietta notes the temperature of the cloth surface, using the two thermocouple digital thermometers in the foreground.
A more elaborate experiment, with a second thermocouple set on the metal surface, would define the practical limit to ventilation. In the experiments described below, the cloth was laid on a metal plate, which provided conductive heat from one side.Which Fabric Evaporates Moisture the Quickest?
Essay example. because I participate in many sports, and am always running around and I sweat a lot! I figured that if I could wear clothing that evaporates water the quickest, I could stay dry. There are many companies that make athletic apparel, such as Nike, UnderArmour, Adidas, and Reebok. Essay on Which Fabric Evaporates Moisture the Quickest?
- INTRODUCTION How fast do different fabrics evaporate moisture. There are many different types of fabrics that are used for clothing. Note that the air at C will be much more effective at removing moisture, because it can entrain water molecules at a concentration of nearly 17g/m 3, instead of less than 13g/m 3 at the lower temperature of the unheated plate.
Furthermore, as figure 1 indicates. Cotton fabric printing with reactive dye using guar gum A 3-per cent concentration of Guar Gum will be the better alternative for large-scale printing of cotton in home furnishing industries, find Priyanka Kesarwani and Archana Singh.
Cotton Biology essay: describe the. Wool is your top insulating fabric of anything available but, as many folks bemoan, it is a notoriously difficult fiber to wear against sensitive skin.
Base layers that wick moisture away from the skin are polyester and silk, ideal for thermal shirts, pants and socks.
Cotton is a clammy misery, absorbing any moisture and holding on to it for hours. This is because the new generation of technical fabrics are created to allow moisture through the weave and wick away from the body, where it can evaporate on the surface, keeping you cool.
Technical fabrics can also be waterproof.Download