Heat exchanger fluid outlet temperature determination
If the temperature of the cold and hot fluid in the heat exchanger is provided by the technological conditions, there is no problem of determining the temperature of the fluid. If one of the fluids is only known to import temperature, the outlet temperature should be determined by the designer. For example, with cold water cooling a hot fluid, cold water inlet temperature can be estimated according to the local temperature, and its outlet temperature can be determined according to economic accounting: in order to save the amount of cold water, but the heat transfer area is needed to increase; in order to reduce the heat transfer area, you need to increase the amount of cold water. They are contradictory. Generally speaking, the water source is rich in the region to choose a smaller temperature difference, the larger the temperature difference between water shortage region. However, the outlet temperature of industrial cooling water is generally unfavorable higher than 45, because the solubility of some salts (such as CaCO3, MgCO3, CaSO4 and MgSO4) in industrial water increases with the increase of temperature. If the heating medium is used to heat the cooling fluid, the outlet temperature of the medium can be selected according to the same principle.