The Setting Of The Range Of Temperatures
After necessary chilled water inlet is determined, the necessary temperature range must be set.
From Eq. 1.1, the required flow rate of the coolant dictated imposed cooling is required and the selected temperature range. The more variety, the lower the rate of flow and, consequently, the less energy is consumed for transportation of cooled water through the system. However, if the range is too large, heat exchanger and other heat exchangers systems require increasing the heat transfer surface and, in some cases, the opportunity to meet hidden cooling is reduced.
In the past 10F range was used for the systems of water cooling, which then requires the consumption 2.4gpm/ton imposed cooling load. For small systems with a relatively short pipeline passes the range and speed of flow are acceptable. However, as systems become more and pipelines is done to get more, to use higher ranges will reduce pumping energy needs. Moreover, the reduction in consumption can also result in economies in pipelines smaller installation costs since the pipeline can be used.
On 12F range, the flow rate is reduced to 2.0gpm/t, on 14F 1.7 gpm per ton. For very large campus systems range as high as 16F (1.5 gpm/t) to 20F (1.2 gpm/t) can be used...