Various ODS-free products have been developed by several manufacturers for cooling applications, such as testing heat sensitive avionics, deicing equipment, electrical, and computer components.

ODSs have seen use in many different applications, including that of cooling agents. However, this direct application of chlorofluorocarbons (CFCs) does not lend itself to CFC recovery, and given the production ban, alternatives need to be substituted.

In compressed gas form, CFCs are effective cooling agents. For example, they are effective for heat sensitive electronics or for testing anti-icing instruments like the probe on F-16 aircraft engine intakes. When the pressurized CFC is directed at the component or point of desired cooling and let down to atmospheric pressure, a cooling effect takes place due to the isoenthalpic expansion of the compressed gas. Recovery of the spent gas is difficult; therefore, alternatives must increasingly be substituted. The alternatives that are readily available and also environmentally innocuous are the following:

1. Compressed air-vortex cooling involves use of a vortex tube powered by compressed air. This typically small, hand-held device uses shop air (8 to 15 SCFM @ 80-125 psig) passed through a vortex chamber to produce a cooling effect. Outlet temperatures of approximately -40^o F are produced. However, the supply air must be both clean and dry for proper operation of the vortex tube.



2. Liquid nitrogen from a dispenser flask can be used to spray at the component; however, care must be taken when using the nitrogen gun, as component temperatures can reach -270^o F. Cost is approximately $500.



3. The refrigerant, HFC-134a, can also be used as a freeze spray in place of CFC-12 and HCFC-22, if compressed air and nitrogen are unavailable. However, HFC-134a sprays have been shown to produce higher levels of electrostatic discharge than either CFC-12 or HCFC-22. Be sure to check with the manufacturer before using.



4. The CO₂ component cooler consists of a CO₂ cylinder, a cart to make it portable, and a hand-held dispenser. The CO₂ cylinders are typically procured in 20-lb containers, although other sizes are available. CO₂ is stored as a liquid under about 850 psig of pressure. As it vaporizes, its temperature can drop to less than -100^o F allowing for the formation of tiny dry ice particles. The CO₂ component cooler is not only "ozone-safe" but is also considered a low-cost, effective option for electronic component cooling.

• Reduces the amount of ODSs going into the environment.
• Many alternatives are inexpensive, lower cost than the CFC alternative.

• Some of the alternatives are slightly less efficient in cooling.
• An electrostatic discharge exists with some of the alternatives.

Note: Each alternative has its own unique set of benefits and disadvantages. See the individual Pollution Prevention Opportunity Data Sheets for more specific information about each alternative.

The capital cost of the CO2 component cooler (COMP-CO2LD) system includes the control unit, a 20-lb. cylinder, and a cart that is used to make the system portable. The following economic analysis was obtained from a case study on "Eliminating CFC-113 and Methyl Chloroform in Aircraft Maintenance Procedures" for the government of Thailand by the U.S. EPA Solvent Elimination Project.

Assumptions:

• Number of CC-1 units needed to replace CFC-12: 50
• Cost of CO₂ system: $340.00
• Labor requirements for both systems are approximately equal.
• Number of CFC-12 cylinders used/year: 300
• Number of CO₂ cylinders needed to replace CFC-12 cylinders are equal.
• Cost per CFC-12 cylinder: $105.00
• Cost to refill CO₂ cylinder: $6.00

Annual Operating Cost Comparison for CO₂ and CFC-12 Component Cooling

Click Here to view an Active Spreadsheet for this Economic Analysis and Enter Your Own Values.