EMD water cooling system
Closed Recirculating System / Dry Cooling Tower:
In closed recirculating systems or dry cooling towers, heat absorbed by the cooling water is either transferred to a second coolant, or released into the atmosphere. The word dry is used because the water is never exposed to the air, and as a result, very little water is lost. An automobile engine is a good example of a closed cooling system.
Evaporation is not used in closed recirculating cooling towers. Instead, cool air rushes over a series of small tubes containing circulating coolant. Heat is transferred from the hot liquid inside the tubes to the cool air, resulting in cooling. The coolant is then returned back into the engine.
Average Temperature Change: 10-15° F (6-8° C)
Amount of Water Used: Negligible
Examples:
Automobile Radiator
Chilled Water Systems
Food Temperature Controllers
Liquid-to-Liquid Cooling Systems
The simplest of these systems is a liquid-to-liquid cooling system. In this type of system your plant has an abundance of some type of cooling liquid already available but you do not want to provide this coolant to the compressor. For example: you have well water available but you do not want to put the well water through your new compressor because the water quality is very poor (lots of dissolved solids like iron and calcium etc.), and you have had trouble with the well water fouling your heat exchanger/s in the past.
A liquid-to-liquid cooling system is an ideal fit for this situation. It uses the well water on one side of an intermediate heat exchanger and a coolant such as glycol and water on the other side of the intermediate heat exchanger in a closed loop to cool the compressor. The heat is exchanged through the intermediate heat exchanger without fouling the heat exchanger/s. Fouling of the intermediate heat exchanger will likely happen on the well-water side, however, if the intermediate heat exchanger is selected properly it can be taken apart easily and cleaned. The most common intermediate heat exchangers are either plate and frame or shell and tube type. Coolant temperatures of 5 degrees above the plant cooling “water” are possible with a liquid-to-liquid type system. In the well water example above if the well water is available at 55 F the liquid to liquid cooling system is capable of supplying 60 F coolant to the load.
The strength of a liquid-to-liquid cooling system is that it is relatively inexpensive to purchase and install. The components can be installed inside or outside. The system is inexpensive to operate with only the closed loop pump using any additional energy. Maintenance is relatively simple demanding only a periodic inspection, lubrication, and cleaning of the heat exchanger as necessary.
Closed-Loop Dry Cooling Systems
A closed-loop dry cooling system is very much like the radiator in your car. The system uses an air-cooled fluid cooler to transfer the heat from the closed-loop coolant fluid pumped through rows of finned tubes that have ambient air blown/drawn across them. The basic components to a closed-loop dry cooling system are the fluid cooler, which contains the air to liquid heat exchanger with the fan/s, the pump and control skid, the coolant, and the field installed system piping. The closed-loop dry cooling system fluid cooler will be located outside and use the ambient air to reject the heat. Coolant temperatures of 5 to 10 F above the ambient dry bulb temperature are possible with a closed-loop dry cooling system. The system is relatively inexpensive to operate with only the coolant pump and the fluid cooler fan/s using energy. The fan/s are thermostatically controlled to regulate the temperature of the cooling fluid so that the load is not over or under-cooled. Periodic cleaning of the fluid cooler may be necessary due to dirty atmospheric conditions at the site location. Fouling of the fluid cooler is typically caused by dirt, leaves, cotton-wood seeds, etc.
21 авг 2024
