There are six fundamental sorts of cooling systems that you would be able to choose from to meet the cooling wants of your load. Each one has its strengths and weaknesses. This text was written to determine the different types of cooling methods and determine their strengths and weaknesses in order that you may make an informed selection based mostly in your wants.
There are six primary forms of liquid cooling methods:
The only of those methods is a liquid-to-liquid cooling system. In any such system your plant has an abundance of some kind of cooling liquid already obtainable but you don’t want to provide this coolant to the compressor. For instance: you might have well water accessible but you don’t want to put the effectively water via your new compressor because the water high quality could be very poor (plenty of dissolved solids like iron and calcium and so on.), and you have had bother with the effectively water fouling your heat exchanger/s up to now.
A liquid-to-liquid cooling system is a perfect fit for this case. It makes use of the properly water on one side of an intermediate heat exchanger and a coolant comparable to glycol and water on the other facet of the intermediate heat exchanger in a closed loop to cool the compressor. The heat is exchanged via the intermediate heat exchanger without fouling the heat exchanger/s. Fouling of the intermediate heat exchanger will likely occur on the properly-water facet, nevertheless, if the intermediate heat exchanger is chosen correctly it may be taken apart easily and cleaned. The most typical intermediate heat exchangers are either plate and frame or shell and tube kind. Coolant temperatures of 5 degrees above the plant cooling “waterare attainable with a liquid-to-liquid sort system. Within the nicely water example above if the properly water is offered at 55 F the liquid to liquid cooling system is able to supplying 60 F coolant to the load.
The strength of a liquid-to-liquid cooling system is that it is comparatively inexpensive to buy and set up. The elements can be installed inside or outside. The system is inexpensive to function with only the closed loop pump utilizing any further power. Upkeep is relatively easy demanding only a periodic inspection, lubrication, and cleansing of the heat exchanger as needed.
Liquid-to-Liquid Cooling Systems
Weaknesses of the liquid-to-liquid cooling system embrace periodic downtime of the cooling system for cleansing. This may be offset by putting in a standby intermediate heat exchanger that’s put into service whereas the primary intermediate heat exchanger is cleaned. A standby heat exchanger provides extra price but allows for steady operation of the cooled load whereas cleaning is achieved. This system requires a regulated provide of plant coolant like the properly water instance above for proper cooling of the load. There can be times that the cooled load doesn’t operate at maximum capacity and the plant major cooling “watershould be regulated to insure the load is just not over or beneath cooled.
A closed-loop dry cooling system is very a lot just like the radiator in your automobile. The system makes use of an air-cooled fluid cooler to transfer the heat from the closed-loop coolant fluid pumped by means of rows of finned tubes that have ambient air blown/drawn throughout them. The basic parts to a closed-loop dry cooling system are the fluid cooler, which comprises the air to liquid heat exchanger with the fan/s, the pump and management skid, the coolant, and the sector installed system piping. The closed-loop dry cooling system fluid cooler can be situated outdoors and use the ambient air to reject the heat. Coolant temperatures of 5 to 10 F above the ambient dry bulb temperature are potential with a closed-loop dry cooling system. The system is relatively inexpensive to function with only the coolant pump and the fluid cooler fan/s using vitality. The fan/s are thermostatically managed to regulate the temperature of the cooling fluid in order that the load will not be over or below-cooled. Periodic cleaning of the fluid cooler could also be crucial resulting from dirty atmospheric conditions at the location location. Fouling of the fluid cooler is typically caused by dirt, leaves, cotton-wood seeds, and so on.
Closed-loop Dry Cooling Programs
The strength of a closed-loop dry cooling system is that the unit is quite simple and comparatively simple to put in. The vitality necessities are relatively low and it is easily controlled. Upkeep is normally low requiring only periodic inspection, lubrication, and testing of the fluid.
The weakness of a closed-loop dry cooling system is that it depends on the atmospheric dry bulb. For example, if your location’s design dry bulb is one hundred F in the summer time and your tools requires ninety F coolant; at finest the system can only provide round 105 to 110 F coolant to the load. On this case you would need supplemental cooling to get the coolant temperatures down to ninety F.
The closed-loop dry cooling system also requires free clear air to work effectively. Because of this the fluid cooler should be placed in a location that isn’t affected by the prevailing winds, not too near a building that can permit the warm exhaust air from the fluid cooler to be recirculated again to the fluid cooler, and finally not in a location that has heavy concentrations of mud, dirt, leaves, seeds, etc.
Many times one of the best location for the fluid cooler is on the roof. For the reason that fluid cooler is located outdoors the coolant must also have a focus of some sort of glycol to stop freezing in case your location has a design dry bulb within the winter that dips beneath freezing. If the location may be very cold, the focus of glycol could should be significant to forestall freezing. Glycol concentrations as they improve start to reduce the speed of heat switch. For example, for those who need 50% ethylene glycol concentration with water the heat exchanger tools and the circulate/pressure of the coolant will want to increase to regulate for the glycol focus. Larger fluid coolers and pumps will increase the price of the system over these with lesser concentrations of Glycol/water. This can’t be prevented in colder climates.
Closed-loop Dry System with Trim Cooling
A closed-loop dry system with a trim cooler is similar as the closed-loop dry system but adds a supplemental fluid cooler. This system is often used in a location that has too high of a dry bulb in the summer time to provide the right coolant temperature to the load. With an added liquid-to-liquid trim cooler the customer can use a water source to trim the temperature to the specified set level. Many instances closed-loop dry system with a trim cooler are used to scale back the reliance on metropolis water as a coolant. Metropolis water is becoming expensive to purchase and to dispose of. These systems could also be employed to utterly eradicate the city water usage most months in a yr, thus reducing the plant’s working costs. The system will need to have a supply of free clear air and a regulated provide of plant coolant or city water as with a liquid-to-liquid cooling system.
The power of the closed-loop dry system with a trim cooler is that it may provide coolant temperatures under that of a closed-loop dry system alone. The system will reduce the quantity of plant/metropolis water utilization during the colder months.
The weaknesses of the closed-loop dry system with a trim cooler embody all of those listed for the closed-loop dry system. Additionally, it now requires some secondary coolant throughout hotter instances of the yr. Further piping will be required for the trim coolant to/from the skid. Both the trim cooler and the air cooled fluid cooler will require periodic upkeep and cleaning.
The following system, an open-loop evaporative cooling system is totally totally different than the primary three listed above. This system has the flexibility to make use of the design wet bulb as the idea for the outlet temperature of the cooling water. For instance if the design dry bulb for the situation is ninety five F and the design wet bulb is 75 F, the system can provide approximately eighty two F water to the load.
The open-loop evaporative cooling system cascades water through the honeycomb PVC fill material in the tower along with ambient air blown or drawn by way of the fill to evaporate the water. During the evaporation, the remaining water is cooled to as close as 7 F or increased above the wet bulb temperature. The evaporated water is changed with some type of make-up water system like a float valve. The remaining water and the make-up water are collected in a basin and then pumped to the load and the cycle repeats. On common an open-loop evaporative cooling system requires four GPM of make up and blow down water per 1,000,000 Btu/hr of heat rejected.
Open-loop Evaporative Cooling Programs
The advantage of this system is that the tools is typically cheap. The methods will be easy to make use of in warmer climates however could require extra controls in colder climates.
The weaknesses of any such system are that they normally require an extensive water therapy system. The water remedy system uses expendable chemicals to maintain the calcium and dissolved minerals in suspension. The chemical treatment is necessary to ensure that the cooling tower, piping, and heat exchangers do not become fouled. An inherent difficulty with the open tower evaporative system is that the water that flows via the tower can be the heat switch fluid that is pumped via the load. This water comes involved with the dirty atmosphere. It picks up pollutants such as dust, vegetation, etc. These contaminates find yourself within the heat exchangers and piping and can cause important upkeep issues.
Open towers can have control points in the winter months. They’re designed to run at full load. They do not at all times perform nicely underneath part-loading in very chilly climates. If the basin is part of the tower, a heater is required for chilly weather operation to maintain the basin water from freezing when the load shouldn’t be present. The piping will usually require insulation and heat hint in cold climates to prevent freezing. A drain can be required for blow-down of the water to maintain the conductivity in examine from the fixed evaporating and concentrating of the dissolved solids. Make-up water is frequently required from external source similar to city water or handled properly water, and so forth. Biological control of micro organism, slime, and mold are major considerations for correct operation of an open evaporative tower system.
A closed-loop evaporative system is a hybrid system. The closed loop evaporative system is an open tower with a closed-loop heat exchanger constructed into the tower. The tower water stays outside in the tower and does not circulate via the coolant piping. The coolant piping is a closed loop, with a glycol/water answer flowing from the tower to the load and again. The separate tower water is pumped from the basin to the top of the tower and sprays across the heat exchanger (normally an array of tubes) with air blown or drawn through the tower across the heat exchanger the place evaporation of the water transfers the heat from the closed coolant loop to the ambient air. The remaining tower water falls to the basin where it is again pumped as much as the top of the tower and repeats the process. The closed-loop evaporative system tower water requires make-up water, chemical remedy, a drain, cold weather basin heater, and blow-down simply like the open-loop evaporative system discussed above.
Closed-loop Evaporative Cooling Systems
The benefit of the closed-loop evaporative system is that it could actually ship closed loop coolant to the load at roughly 7 to 10 F above the wet bulb temperature. The closed-loop coolant remains freed from contaminates and permits the tools heat exchanger and piping to stay clear. Any contaminates from the environment will stay outside with the tower. Fewer water therapy chemicals will be used because they’re only treating the open water within the tower and never the coolant within the piping and system heat exchangers.
The drawbacks of a closed-loop evaporative system are that you will need water therapy, blow-down, and make-up water for the tower water side of the system. The system would require a drain and heat-traced and insulated piping for chilly weather applications. There is a basin heater required to prevent freezing of the basin in chilly weather off-time operation. The system requires an additional pump related to the tower which circulates the basin water.
The last type of cooling system we are going to focus on is the chilled water system. A chiller usually has a mechanical compression gadget that converts power into compressed refrigerant by utilizing some kind of compressor. The compressed refrigerant is piped to a condenser that rejects the heat from the refrigerant to the environment or some sort of liquid coolant. The compressed refrigerant adjustments state from a gasoline to a liquid within the condenser and is piped to an evaporator the place it’s metered or expanded within the evaporator. The enlargement of the excessive strain liquid refrigeration reduces the temperature of the evaporator. The liquid to be cooled is pumped by the evaporator heat exchanger and heat is transferred to the refrigerant. The low strain vapor is carried again to the compressor and the cycle begins once more for the refrigerant. The coolant flows from the evaporator heat exchanger to the load the place the heat is transferred to the coolant in the load heat exchanger and then returns back to the evaporator to repeat the cycle.
Chilled Water Cooling Systems
The strengths of a chiller are that it could possibly produce coolant temperatures far beneath the design wet bulb or dry bulb. It isn’t as dependant on the ambient temperature for the outlet coolant temperatures.
The weaknesses of a chiller are that it’s a reasonably advanced piece of equipment. Chillers price greater than all different forms of cooling equipment. They require specialized periodic upkeep and educated certified repair technicians for correct operations. Chillers themselves introduce additional heat loading from the compressors that should even be removed in the condenser. The facility required to operate a chiller is much increased than the opposite sorts of cooling systems discussed above. Chilly weather operation of chillers requires special additional components on the chiller. Load variations could require particular controls and/or multiple chiller circuits for efficient operation all adding to the general value of the equipment.
As you’ll be able to see there are many sorts of cooling techniques out there to satisfy your requirements. It’s best to contain your cooling system specialist early in your planning that can assist you choose the most effective system to suit your needs.