冰生成和传热传质现象将水引入到盐水冷水浴

The overall goal of this experiment is to investigate the formation of ice and heat, and mass transfer when water and high concentration cold brine are in direct contact. This method can help answer key questions in the heat and mass transfer field. For example, relating to ice protection and energy storage.

The main advantage of this techniques that it does not require low evaporative temperature and it is efficient. This experiment requires 35 to 40 liters of brine prepared in small quantities. In order to prepare a small batch, begin with four kilograms of water in a plastic five liter beaker and one kilogram of sodium chloride.

As measured by an electronic scale. Poor the salt into the beaker with water and then stir the mixture until the solution is clear. The next step is to test the density with a youtube density meter.

Use a 10 milliliter syringe and draw about 10 milliliters if the solution as a sample. Inject the sample into the youtube density meter and insure that there are no air bubbles before proceeding. At the density meter controls enter the temperature of 20 degrees celsius.

Then start the measurement. Compare the reading with the reference value and adjust the water and salt content as necessary. The collect brine should be stored in a freezer, held at minus 40 degrees celsius.

It should be kept there until it reaches it's freezing point, 48 to 72 hours. The freezer will hold other items prepared for the experiment. There are two blocks of ice that will be used for injecting water.

These are made by pouring one liter of water into a container and freezing them. There are also two ice shells in the freezer. One ice shell is in a five liter beaker and should be able to contain two liters of water.

The other ice shell is in a two liter container and should have a one liter capacity. There are three principle elements to the experiment set up. There is brine tank kept cool using heat exchangers in which has a window for observing the flow.

There is a tank in which secondary coolant is pumped through the brine tank heat exchangers. The secondary coolant is kept cool using three refrigeration units. The arrangement is depicted in this schematic.

The secondary coolant tank should be filled and cooled by refrigeration units for 10 to 16 hours until the coolant is a minus 25 degrees celsius. When the secondary coolant is ready transfer 30 liters of brine from the storage tank to the brine tank of the experiment. Once this is done start circulating the secondary coolant through the heat exchangers.

Regularly monitor the temperature of the secondary coolant. Maintain it between minus 17 and minus 19 degrees celsius by turning the refrigeration units on and off. Next, prepare for injecting water into the brine.

This requires working with the pre made blocks of ice, an insulated five meter beaker, about three liters of water, and a 100 milliliter glass syringe. Place the pre made block into the insulated beaker. Then pour approximately three liters of water into the beaker.

Monitor the water temperature and maintain it at two degrees celsius. Next, work with the 100 milliliter glass syringe. The syringe should have a silicon tube connected to inject water into the tank.

Use the tube to fill the syringe with two degrees celsius water from the beaker. Then place the open tube into the brine. Support the tube so its open end is held horizontally in the brine.

Observe the flow through the tanks window and inject the water at a constant rate. For ice collection, have a table with a scale near the set up. Obtain a container for sample collection.

Place it on the scale and tear the scale. At the brine tank, use shiv to collect a sample. For dry collection, scope out the ice and then shake the shiv to remove the brine.

Take the sample to the scale, put the ice in the container, and record its mass. Wait for the ice to melt, then use a ten milliliter syringe to take a sample of the water. Move to the density meter and inject the sample.

Measure the density at a temperature at 20 degrees celsius and record the value. For the wet collection procedure, have a table and scale near the set up and the freezer. In addition, start with a beaker about five liters of room temperature tap water.

Continuing by opening the freezer there. Find the prepared five liter beaker with and ice shell and add room temperature tap water to fill the beaker completely. Wait for the water in the beaker to cool to zero degrees celsius.

For the next step have more tap water ready. In the freezer make sure the previously prepared two liter beaker is accessible. When the water that was added to the five liter beaker reaches zero degrees celsius, titanic into the two liter beaker.

Then use room temperature water to fill the five liter beaker again. Close the freezer until the water in the two liter beaker is needed. To collect a sample.

First, tear a container on the scale. Next, go to the brine solution with a shiv. Scope out some of the ice without shaking it.

Then retrieve the two liter container from the freezer and pour 200 to 500 milliliters of the zero degrees celsius water over the collected ice. Shake of the fluid on the ice before proceeding. Then place the ice in a container on a scale and record its mass.

When the ice is melted, collect a sample to perform a density measurement. Move to the density meter and inject a sample. Measure a density at a temperature at 20 degrees celsius and record the value.

This data is for a water injection angle of zero degrees with respect to the horizon parallel to the floor. The fraction of water converted to ice is along the vertical axis. The brine temperature is along the horizontal axis.

The three upper sets of data are different brine concentrations and ice collected with the wet collection method. The line represent linear fits to the respected data sets. For the three studied concentrations, as the brine concentration increases the diversion ratio decreases.

The three lower sets of data are for the same brine concentrations using the dry collection method. In all data sets the trend is for a higher conversion ratio with lower temperature. Once mastered, this study can be done in three hours if it's preformed properly.

While attempting wet collection it's important to be consistent when applying force especially of the salt water to reduce these discrepancies in the results. After watching this video you should have a good understanding of how to maximize the water to ice conversion ratio by adjust brine temperature, concentration, and the radiology of the injected flow.