Temperature control units with variable speed pumps
7 December 2017
Which is the correct pump specification for my temperature control unit? Until now it has not been an easy question to answer as the demands, especially on universal units for injection moulding can be so widely spread, that the exact pump specification never really existed.
Due to basic physics, if a pump runs at a constant speed and varying cooling channel dimensions are used on separate individual consumers (mould tools etc.) then an efficient solution is not possible. The answer to the question above therefore should be: Adapt the characteristic to the application by changing the pump speed to obtain the desired flow rate with minimum energy consumption.
Flow conditions in the tempering channel and thus, the quality of heat transfer from the heat transfer medium to the mould are defined by the flow rate, depending on the channel cross section. Very low flows demand only little drive power; however, the heat transfer and thus the temperature distribution in the mould are not at an optimal level. When increasing the flow beyond the optimal operating point, the heat transfer can only be increased minimally, but the necessary drive power increases disproportionally. Then comes the question: Which is the correct pump speed?
HB-Therm presents an efficient solution with its Thermo-5 temperature control units as they are now available with an optional variable speed controlled pump. They offer active support for the user to select the correct pump speed. In Eco-mode the unit determines the necessary flow rate automatically for the given application and thus enables energy saving without sacrificing process quality. When the unit is operating in an energy saving range it will display a green leaf on its screen.
The new Thermo-5 units can also be integrated via suitable interfaces into process installations, where the pump speed can be controlled by the supposed flow rate control. This control strategy is mainly recommended for parallel circuits with active flow rate control.