Portable Chillers

Portable chillers are self-contained chiller systems with all the necessary components of larger systems with the advantage of portability. The three types of portable chillers are air cooled, water cooled, and remote condensers. Each type is designed for small process loads where special process fluids, flows, pressures, and temperatures are necessary.

The portability of portable chillers makes them ideal for laboratory testing, research, and product testing. The cooling capacity of a portable chiller ranges from 500 lbs (227.8 kg) to 60 tons, with various applications that include cooling lasers to assist in food preparation and production.

All aspects of a portable chiller are the same as more dynamic and larger systems, modified to meet the demands of a smaller, more convenient system. As with larger chillers, the key component of portable chillers is their compressor that compresses refrigerant gasses to increase their pressure. The compact design of portable chillers makes it possible to easily move them from one location to another due to their ease of installation and low maintenance. Portable chillers are the ideal choice for locations where a central chilling system is too costly or does not fit an application's needs.

Components of a Portable Chiller

Although portable chillers can be air cooled or water cooled, air cooled portable chillers are more convenient and easier to move. Water cooled portable chillers require a connection to a cooling tower, necessitating additional cooling lines. With an air cooled chiller, the dissipated heat from the chilling process can be used to heat the surrounding air. The design of a portable chiller is based on a refrigeration cycle where heat is removed from the refrigerant such that it cycles to release cooled air.

Compressor

A portable chiller normally has a scroll-type compressor, also known as a spiral compressor or scroll pump. Scroll compressors are positive displacement compressors that operate using the internal compression of gasses. They have two spiral-shaped elements, with one spiral overlapping the other. The upper spiral disk remains stationary, while the lower inner spiral disk moves orbitally.

The two scrolls oscillate but do not make contact. The refrigerant gas is compressed into air pockets during the rotation and oscillation. The orbiting scroll draws in the refrigerant gas through the inlet. Once the gas is pressurized, it is discharged through the outlet to the condenser. The purpose of the compressor is to prepare the refrigerant gasses for the condenser. When the gasses enter the compressor, they are at low pressure and temperature. Therefore, the compressor increases the pressure and temperature of the gasses for processing by the condenser.

Condenser

The condenser is the heat ejector of a portable chiller. It consists of coils that contain the refrigerant and help the system lose its heat. For portable mobile chillers, the condenser is small and compact, capable of fitting within the unit's design. The coils are made of copper or aluminum, with aluminum being the better choice since heat can transfer faster from aluminum.

An essential part of the condenser is the fan or blower that cools the condenser coils and circulates air around them. The fan or blower increases the heat transfer rate and enhances the cooling process. As the refrigerant gasses cool in the condenser, they change from gas to liquid before moving to the evaporator.

Expansion Valve

When the refrigerant leaves the condenser, it enters the expansion valve between the condenser and evaporator. The expansion valve controls the refrigerant by reducing its pressure and increasing its volume, which makes it capable of picking up unwanted heat in the evaporator. There are several types of expansion valves, with thermal, capillary, and electronic expansion valves used in portable chillers.

Evaporator

The refrigerant is boiled back to a gas in the evaporator by the heat absorbed from the cooling fluid. The evaporator is a heat exchanger where the heat from the coolant is transferred to the flow of the refrigerant. In the process, the refrigerant evaporates and changes from a low-pressure liquid to a vapor as the coolant temperature lowers. Then, the refrigerant gas returns to the compressor to begin the next cycle of the cooling process.

Uses for Portable Chillers

Although many portable chillers are on wheels and easily moved, the term portable chillers refers to a set of chillers with all of the components of a chiller contained within a single footprint. Portable chillers are supplemental, backup, or emergency cooling systems ideal for various applications.

Medical Scanning Technology

CAT, PET, and MRI scanners generate a great deal of heat that can interfere with their primary function. For these medical devices to provide accurate data, they need to be cooled to protect the device, patients, and medical staff. Portable chillers are used to maintain proper temperature control.

Biodiesel Production

Breaking down biomass requires temperatures up to 1800 °F (982 °C), which is crucial to the success of the process. Portable chillers provide the necessary temperature control and regulation.

Anodizing

Anodizing is a process where a material is submerged into an electrically charged acid bath to create an anodic oxide coating. Proper temperature control is necessary to ensure the coating is equally applied and adheres to the material's surface. Portable chillers help maintain and regulate the temperature of the electrolyte liquid.

Extruded Plastics

In the extrusion process, a heated billet is forced through a die profile to create a specific cross-section. It is a highly productive and efficient process that produces high-quality parts. For the process to be successful, the billet must remain at a constant and consistent temperature, which is achieved with a portable chiller.