Central Chillers for Plastics Processing
A chiller is a device that transfers heat. It removes heat from one place and transfers it to another using mechanical refrigeration. This removes heat from a process load and transfers it to the surrounding environment. Plastics processors will employ chillers if they need a lower process fluid temperature than a more straightforward solution, such as a cooling tower, can deliver.
The purpose of Central Chillers for Plastics Processing Portable is to provide a constant flow of coolant to the cold side of a process water system at a “leaving water temperature” (LWT) of around 50 degrees Fahrenheit (10 degrees Celsius) that the user predetermines. After that, the coolant is circulated through the process, removing heat from the moulds and equipment as it returns to the back of the process water system. The coolant flow, which is now at a higher “entry water temperature” or EWT (five to ten degrees warmer than LWT), then re-enters the chiller, which performs the following three functions:
It does this by extracting heat from the process coolant, then releasing the heat into the surrounding environment, and finally bringing the temperature of the coolant down to the LWT that is wanted, making it suitable for recirculation.
A chiller is a vapour compression mechanical refrigeration system that is connected to the process water system using a device known as an evaporator.
The evaporator is a heat exchanger that transfers the heat that was picked up by the flow of the process coolant to the flow of the fluid that is used in the refrigeration process. The temperature of the process coolant is brought down to the level of low-water-temperature that is needed while at the same time the refrigerant evaporates, transforming from a low-pressure liquid into vapour.
The refrigerant then goes through a compressor, which serves two purposes.
First, it eliminates the vapour of the refrigerant in the evaporator. It ensures that the pressure in the refrigerant line of the evaporator (the vapour pressure) stays low enough to absorb the heat from the process at the appropriate rate.
Second, it increases the pressure in the vapour of the refrigerant being released into the atmosphere. This is done to ensure that the vapour’s temperature is high enough to allow it to release its heat when it reaches the condenser, where the vapour condenses back into a liquid. A refrigerant transition from a vapour to a liquid state gives off latent heat. This heat is transferred to the surrounding environment in a cooling medium, such as water or air.
Because of this, most portable and central chillers have a condenser that is either cooled by air or water.