Why chilled water

Lack of a well-performing insulation system can interfere with limiting heat transfer and could lead to high operating and energy costs. Chilled water pipes are subject to moisture, which is one of the reasons why closed cell insulation is beneficial.

This helps prevent ingress of water or condensation into the insulation which could result in corrosion or the formation of mold.

As these lines are often located inside important and public buildings, the insulation should also be incombustible and should not give off toxic gases or fumes in case of fire. Its constant insulation efficiency can help prevent heat gain, possible dripping due to surface condensation and help limit formation of corrosion of the pipes. The information relating to the products and systems contained on this website is provided in good faith and for general information purpose only.

Any variable flow application CHW or CW increases the intricacy of the design, construction, and operation of a system, but at times of low load and corresponding reduced flow rate requirement, may offer significant pump energy savings. Selecting a CF versus a VF system requires many considerations during the design effort. As with any design, the designers of a CHW system should consider various options and equipment through discussions with the owner, and recommend one or more of these options to meet the project goals and performance requirements.

Among the many important items to consider regarding these system designs are any system constructability and budgetary constraints, system operability, operations and maintenance costs, and energy consumption costs. Or the building may have some combination of CHW distribution piping systems connected to a larger thermal utility network that serves several buildings simultaneously from a large, remote central plant arrangement.

The first step in designing any efficient, effective HVAC system for a building is to perform an accurate building load calculation and energy model. The type of CHW system designed and installed and the amount of the CHW required for these cooling loads will be a major component in the overall building energy usage.

An independent, stand-alone single chiller system type is relatively easy to design and operate, but even though the first cost is less, this system is typically the least energy-efficient design for buildings. This is because chillers are normally selected within a small percentage range of the calculated design process loads of the building or buildings they serve.

The chiller operates at full capacity for only a small percentage of time. Designers should select a chiller at a higher part load efficiency to maximize energy savings based on the larger run hours at part load. If a single chiller fails, or a related single pump or cooling tower associated with the chiller fails, the CHW system or all cooling capacity is lost.

Thus, many CHW systems have two or three redundant equipment components installed. This provides some level of backup and allows for more efficient operation at low-load time periods. Figure 2 is a schematic that shows a building single-chiller CHW system. In both single-chiller and multiple-chiller arrangements, the CHW loop can be either constant flow or variable flow which must remain above manufacturer required minimum flows. The use of two or more chillers with part load capacity will provide more opportunities to improve the CHW system part-load performance and help reduce energy consumption, and can greatly assist in providing redundancy in the design.

These chillers can be designed to operate in series or parallel modes. Figure 5 is a parallel chiller arrangement. Figure 6 shows a large ton chiller, which is one of three in a parallel arrangement. The parallel arrangement is more common with chillers that are typically the same type and size, but is not mandatory.

The chillers do not need to be sized individually to meet the building capacity but can be operated together to do so. In this case, the CHW will flow in parallel paths through both chillers and will generally experience similar pressure drops. In a series chiller arrangement, the CHW flow will go through both chillers in series and the water pressure drop is additive.

In both arrangements, one or both chillers may be on variable speed drives VSDs and the CHW, and even the condenser water, loop can be either constant flow or variable flow. Finally, the building or buildings may not have any chillers or cooling towers, but only CHW distribution piping systems connected to a larger thermal utility network from a remote CHW central plant CP arrangement.

Typically these central CHW plants serve multiple buildings of various types ranging in function or use, size, construction materials, age, and cooling loads. Some buildings may have more than one CHW loop inside its walls.

Another term for this type of arrangement that is becoming more common is a district cooling plant DCP that also serves a localized campus, whether in a college or university setting, an industrial complex, or large urban mixed-use site.

The design of these DCPs must take into account the diversity of all loads throughout the area they serve including when the different peak loads will occur. See Figures 3 and 4 for schematic arrangements of a larger central plant. Regardless of the CHW plant location, an overall campus thermal utility master plan can provide the design options for consideration and evaluation of pumping schemes for circulating CHW.

There are two common configurations for CHW plant pumping schemes that will work with the selected CHW equipment to deliver the CHW to a building or group of buildings:. In the PS scheme, the primary CHW loop is typically constant volume flow while the secondary loop is variable volume flow.

There are still some older systems where the secondary loop is also constant volume. The compressor is what drives the entire process and is also the component which uses the most energy. That is why it is important to have an efficient compressor. In the condenser of the chiller, then, the heat is transferred to the condenser water in case the chiller is a water-cooled, or directly to the outside air if it is an air-cooled. Since chilled water systems act as a centralized cooling system providing cooling for an entire building or multiple buildings, they are often a practical option to centralize Air Conditioning equipment in a single location rather than installing many different pieces of equipment in different places.

That, for instance, is a great way to simplify the access to the units for maintenance. Also, using a chilled water system provides better energy efficiency than smaller, individual systems. That is another important aspect. While chillers might be a more expensive initial investment, they allow have a more efficient system and save money on energy consumption. Therefore, they allow a good Return On The Investement in a relatively quick timeframe.

Other than efficiency, there is another important aspect to consider as a reason to choose a chiller system. For instance, large commercial buildings requiring a substantial amount of cooling, often use chillers because of their cost-effectivess.

So, since many types of air conditioners cool the air through direct contact with refrigerant lines, there are cases when chillers might be a better solution than air conditioners, which are also more difficult to install in large buildings.