Refrigeration for Dry Screw Vacuum Pumps

Refrigeration for Dry Screw Vacuum Pumps

Refrigeration has been a historically reliable method of preservation for millenia. By introducing and storing organic material in and to low temperatures, the growth and reproduction of certain detrimental microorganisms is discouraged and the decay rate of the material is drastically stunted. By introducing vacuum technology into this principle to create evaporative cooling, or vacuum refrigeration, the process becomes quicker, easier, and higher quality.

Applications of Dry Screw Vacuum Pumps

Vacuum refrigeration is the process by which vacuum is used to flash-cool products of organic origin, such as produce, processed foods, distributed dairy goods, and high-water content liquids for storage or further processing. A vacuum pump is connected to a condenser and cooling chamber where the product batch is loaded. Plantation and farm products retain moisture from their growth; this spans anywhere from cattle to cabbage. Once the load is in, the pump begins to evacuate the chamber. Lowering the pressure within the chamber lowers the boiling point of the water held within the products as the atmospheric pressure supports the liquid’s intermolecular forces to hold it in its phase. The result is that the water evaporates at a much lower temperature than that in atmospheric pressure conditions.

When the chamber is held at a constant temperature and the pressure is lowered by the vacuum pump, the latent heat held within the batch is used by the water to evaporate, resulting in a batch of products that is significantly lower temperature than it was at entry into the chamber. Water in particular has a relatively high boiling point compared to many other solvents. Thus, for large batches or operating for longer periods of time, utilizing a vacuum pump and manipulating the pressure and boiling point is more efficient than lowering the temperature of the chamber via a heat exchanger at atmospheric pressure.

Advantages of Dry Screw Vacuum Pumps

The dry screw vacuum pump is often used for vacuum refrigeration applications in many industries. This particular kind of vacuum pump is able to reach up to  Torr for most models, so reaching the approximate 2 Torr for more extreme cooling applications is quite easy. This means that the dry screw vacuum pump does not need to operate at its maximum RPM, which is needed to reach its ultimate vacuum level. In comparison to other vacuum pumps which need the same maximum RPM to generate sufficient levels of vacuum for vacuum refrigeration, the dry screw vacuum pump wears down at a reduced rate and cuts back on energy costs from operation.

This is due to the lack of a working fluid in the dry screw vacuum pump hindering performance by limitations of vapor pressure. Without a working fluid, the dry screw vacuum pump does not need oil maintenance and changing, nor does it need post-filtration and disposal treatment because the lack of a working fluid like pump oil completely disposes of the risk of process gas contamination of working fluid. This also means that there is no need for any working fluid circulation system, which brings costs back a bit as well.

The dry screw vacuum pump provides for easy gas purging and easy access to the pump chamber for cleaning and maintenance. The design can be configured with variable pitch, which adjusts the energy consumed depending on the required suction of the vacuum pump over time. Even without the variable pitch, the dry screw vacuum pump design is inherently efficient with a high CFM-to-HP ratio compared to other vacuum pumps. In total, the dry screw vacuum pump is energy efficient at the required vacuum level and is simple to maintain.

NES Company Inc. is proud to offer our NSP Series dry twin screw vacuum pumps. Offered with the pumps are optional kits, such as gas ballast kits and exhaust silencer kits, so that each industry and application can have an NES dry screw vacuum pump that is tailor-made and specialized for its intended function. NES Company Inc. also offer spare parts kits so that DIY simple repairs can be even smoother of a process, cutting downtime and boosting efficiency, all at our competitive pricing. We at NES Company Inc. place importance on timing and efficiency, and we are more than happy to prove this with our NSP Series dry screw vacuum pumps.