What is a water-cooled chiller?
A water-cooled chiller is one of the types of chillers that removes heat from it to cool the water used in projects or industrial or domestic structures and re-enters the water into the operation cycle. In fact, chillers transfer heat from a space that needs temperature control and transfer it to another space. Therefore, the chiller is not a means of generating cold, but a means of dissipating heat, and its task is to facilitate the transfer of unwanted and undesirable heat caused by the activity to a place outside the system.
A cooling tower is specifically designed for the water-cooled chiller. Because condensers of water-cooled chillers use water as their stimulant and cooling material. Because wet surfaces are more successful at transferring heat and also do compression work at wetter bubble temperatures, the efficiency of water-cooled chillers increases.
How does a water-cooled chiller work?
The cycle of water-cooled chillers, like any other chiller, consists of four main members: evaporator, compressor, condenser and expansion valve, in each of which a thermodynamic process takes place. The way the chiller works is that the refrigerant is delivered to different phases of the material at different pressures and temperatures to cool the water instead and pump it out of the chiller. In fact, the main work of chillers is based on the phase change or physical state of the refrigerant or refrigerant. In the meantime, the work of water-cooled chillers is based on the condensation of steam or gas.
The first step in chiller operation:
The starting point of this cycle is where the water in the production process enters the evaporator to enter the chiller cycle.
In this part of the cycle, the heat absorbed by the refrigerant first shows itself in the form of a liquid-to-gas phase change. As the refrigerant absorbs the heat of the water, the environment in contact with this part drops in temperature, so the water leaves at a lower temperature. This water enters the fan coils and brings cold air to the desired spaces.
In fact, an evaporator is a place that, in addition to the current cycle, participates in another cycle, and that cycle is between the evaporator and the water outlet to the cooling devices. In fact, hot water enters the chiller evaporator and then cools it out to be pumped throughout the building to the desired location.
The gas refrigerant, which had reached the gas phase in the pre-liquid state, then enters the compressor. In the compressor, the gas condenses and the temperature and pressure increase so that it can enter the next stage with high pressure. This increase in pressure and temperature as it exits the compressor is important because the refrigerant needs to release heat from inside the condenser, so it must carry enough heat to the condenser.
Another key function of the compressor is to draw refrigerant into the evaporator at the appropriate time so that the pressure inside the evaporator remains high enough to absorb heat again.
The third step takes place inside the condenser. High-temperature gas enters the condenser. In the condenser, the gas refrigerant is converted to a high-pressure liquid that is saturated. This is a constant pressure process.
On the other hand, since the condenser is present in another cycle between the cooling towers, water enters the cooling tower after the temperature rises for the water. Because cooling towers in water-cooled chillers have the main task of cooling the consumed water and the condenser uses this water as its driving material.
This is where the unwanted heat of the water disappears and the water temperature is brought back to the desired low temperature. The heating process that we mentioned earlier takes place in the condenser to release the gas refrigerant from the heat itself, the heat source that is now being talked about and needs to be eliminated by the cooling tower. In this way, the water coming from the condenser to the chiller cooling tower is in contact with the airflow and transfers its heat to the air, then goes back to the condenser.
The fourth and final step:
The expansion valve is the last stage that the refrigerant goes through. This milk, as its name implies, expands and reduces the refrigerant. These processes that take place on the refrigerant in the expansion valve cause the refrigerant to become a mixture of liquid and gas. Eventually, the same compound re-enters the evaporator to resume the cycle with hot water re-entering the evaporator from another direction.
Advantages and disadvantages of water-cooled chiller
One of the advantages of water-cooled chillers over cold air chillers is that they take up less space and can be installed indoors. This can reduce the maintenance and repair costs of the chiller to some extent and increase its useful life. The next item goes back to the longer useful life of the water-cooled chiller. Water-cooled chillers are known for their high stability and useful life compared to other types of chillers.
One of the reasons why it is said that water-cooled chillers have better performance and higher efficiency than other types of chillers is their higher bubble temperature. Since the temperature of a wet bubble is always lower than that of a dry bubble, there is a large difference between the activity of a water-cooled chiller at a certain temperature and pressure and the activity of a cold air chiller at the same temperature and pressure; Therefore, the refrigerant is active with significant pressure and temperature difference, and this gives the chiller a more useful performance. Of course, it should not be forgotten that the positive performance of the chiller goes back to other criteria.
In terms of the mere use of water-cooled chillers, if we ignore the costs of water supply and the initial installation costs of water-cooled chillers, this chiller
They seem to be more economical, otherwise, it is better to use cool air chillers if the initial costs are important for the consumer and are limited for them.
One of the main disadvantages of water-cooled chillers is the need for a large amount of water. Also, despite the maintenance of water-cooled chillers in closed environments, these chillers still have many different parts in them, which increases the total cost of maintaining the chiller.
Applications and limitations
As mentioned earlier, water-cooled chillers are used for domestic and non-domestic purposes. Cooling water chillers can be found in large and medium-sized structures and buildings, such as hospitals, airports, manufacturing plants, industrial workshops, shopping malls and even residential buildings, but all of this is provided that there is sufficient water to meet the water-cooled chiller needs. . Finally, it can be concluded that water-cooled chillers are suitable for high or medium capacity installations that have sufficient access to water and do not face the problem of water shortage. Also, the use of these chillers is not recommended in wet cities.
In fact, one of the limitations of using water-cooled chillers is that they use very high amounts of water. As such, the water-cooled chiller is not suitable for areas struggling with water shortages and may not be responsive. Also, water supply has its own costs.