Aug 5, 2019
The task of a cooling device is to deliver coolant with a given temperature and a given flow rate into a cooling system.
Within each cooling channel there is a pressure drop. The pressure drop depends not only on the flow rate.
Furthermore length and geometry of the cooling system play an important role in the occurring pressure.
The pump curve shows the maximum flow rate at a given pressure rate.
If the pressure drop in the cooling channel is higher than suggested in the pump curve, the flow rate will drop.
As actual value the flow rate is shown, which is the maximal possible for the given pressure.
In this case the cooling channel needs to be adjusted or another cooling device should be used.
Nov 11, 2021
The flow pattern of a fluid can be defined by the dimensionless quantity called Reynoldszahl.
It is the ratio of inertial forces to viscous forces.
Calculating the Reynolds number of a fluid we need to multiply the velocity with a characteristic linear dimension and divide it by the kinematic viscosity.
The critical Reynolds number where the flow behaviour changes from laminar to turbulent flow is approximately for tubes 2300.
In the plastic industry the Reynolds number is important for the subject of the cooling system.
Temperature Control: Change from
laminar to turbular flow
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This glossary of plastic industry is provided by PLEXPERT Canada Inc.
Jul 4, 2019
The name compression chiller refers often to system cooler.
In the injection molding industry, they are used to draw the thermal energy from the coolant.
Cooling channels use the coolant with a lower temperature, for example, to regulate the flow temperature.
In a system cooler, the consumption water is actively cooled by compression.
The usual temperatures in industrial/plastic application are in between 5 °C to 25 °C.
System coolers are divided into:
1. Air cooled:
In the air-cooled version, the waste heat (condenser energy) is released into the ambient air. The advantage here is that the system cooler works independently, without on-site cooling network.
2. Water-based:
In the case of water-based chillers, the warm water is returned to an on-site water cycle (domestic water, well or river water).
Image 1: System cooler as small as tabletop unit type SC..K
Image 2: Temperature Control: Floor model type SC..S.
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This glossary of plastic industry is provided by PLEXPERT Canada Inc.
Aug 1, 2019
The flow behavior of a fluid is described by its movement.
A vortex forward movement is called turbulent flow.
A tube with a Reynolds number higher than approximately 4000 will have this kind of flow behavior.
Because of the turbulent flow new coolant is brought to the wall of the cooling channel to take on heat.
After that it will move to the center of the cooling channel and from there back to the wall.
Due to this movement more heat can be taken by the coolant and hence the cooling is more efficient.
Therefore turbulent flow is recommended for a coolant.
Nov 18, 2021
To process plastic, an injection mold must be brought to a certain temperature.
The thermal energy introduced by the melt must be dissipated to ensure that the temperature in the mold is as uniform as possible.
These tasks are performed by the temperature control system installed in the mold.
This is usually formed by bores, some of which are provided with plugs to guide the coolant (usually water).
The tightness of the individual channels in the cooling system is ideally carried out before the mold is set up.
For this purpose, water is pumped into a circuit via a pump and kept under pressure for a certain time.
If water does not leak at any point, the leak test of the sewer is complete and the next sewer can be tested.
