Texas Utilities now recommends that its customers install the unit on all commercial air conditioning and refrigeration systems. That’s a strong reason for commercial hvacr contractors to consider recommending the unit, in turn, to their customers.

So how does it work?

The RMS is a modified liquid receiver with a fixed impeller located in the bottom. It’s installed in the liquid line of a system right after the condenser.

The refrigerant expands and cools as it enters the unit’s vessel. The vessel increases the heat-rejection space of the condenser coil. It generates a vortex flow, which creates a low-pressure area in the center of the liquid.

This low-pressure area allows the refrigerant to expand and subcool.

Through the Vortex

The phenomenon of vortex flow pulls the cooler mass to the center, the low-pressure area, and the warmer mass is pushed to the outside. In this way, the vortex flow allows for additional heat rejection through the surface area of the vessel.

At the bottom of the vessel is a fixed impeller that forces the liquid into a turbulent flow. This type of turbulent, uniform flow has less negative restriction than that associated with laminar flow.

Over time, oil collects on the surface area of the tubing, developing an insulation barrier that slows the transfer of heat. The turbulent flow caused by the impeller in the base of the RMS assists in removing this oil barrier, thus promoting better heat transfer and reducing the liquid temperature still more.

Since the refrigerant enters the metering device at a lower temperature, it can absorb more heat. This results in a colder evaporator coil, which will remove more moisture and latent heat from the supply air.

As the evaporator coil becomes colder and approaches freezing temperature, the compression ratio is reduced. Reduced compression ratio results in less compressor work, and thus reduced energy cost. And a colder evaporator coil results in increased system capacity and less running time for the compressor.

When the evaporator coil approaches freezing and the compression ratio lowers, the flow of liquid out of the condenser coil will slow down, allowing the refrigerant to back up in the condenser.

This causes the vortex to become shallow and cavitate, pulling warm gas vapor from the upper part of the vessel. The hot gas thaws any frost that may form on the evaporator coil.

This is like having hot gas defrost without additional controls or components, the company says.

Less Energy, Shorter Run Time

Lower evaporator coil temperatures additionally result in greater dehumidification and latent heat removal, a lower compression ratio, less energy required to run the compressor, and a shorter compressor run time.

The RMS has no moving parts and requires no maintenance, the company says. Construction is a modified liquid receiver with a fixed impeller pressed in the base and a powder-coat, baked-on enamel expected to last more than 50 years.

The unit is designed to outlast the equipment it is installed on, and can be removed and used again, the company claims.

The company notes that if the system on which the RMS is to be installed has a fixed-bore metering device, it should be changed to a TXV.

The unit is designed to achieve its maximum energy savings seven to 10 days after installation. Payback varies; it usually occurs, however, in less than two years, according to the company. And the user will continue to save for the life of the unit. For more information, contact Chiller Services at P.O. Box 71120, Tuscaloosa, AL 35407; 205-345-4520; scarter@greenthink.com (e-mail).