Comparison of Glycol Refrigeration Dehumidification to Desiccant Dehumidification (continued)  



Chart 2 shows the same rink condition of 60°F @ 40% RH. The total moisture removal of a desiccant unit rated at 10,000 SCFM is shown at 152.66 lbs/hr. this is a continuous per-hour capacity. The desiccant removes water in the vapor phase; no defrost is required. The unit is sized for 10,000 SCFM and will remove approximately three times the water vapor. Desiccant dehumidifiers are more effective and efficient at removing the water vapor at these low humidity levels.

The energy required to reactivate the desiccant load on the system is approximately 425,000 BTU/h. This energy input can be provided as natural gas, propane, electricity or a combination of those and

can incorporate waste heat. Energy recovery is available to reduce this energy requirement by an additional 20 to 30%.

To get an equal amount of dehumidification capacity, you need approximately three times the air flow through the glycol refrigeration system to handle a similar internal humidity load.*

To get a proper comparison for a refrigeration system to remove the same amount of water vapor from the air, we need to compare the energy required to remove 54.41 lbs/hr.

*Actual comparison based on water removal.

  Comparison of Desiccant Dehumidifier Capacity  



Chart 3 shows the desiccant unit only requires 3,305 SCFM to meet the moisture removal of the 10,000 SCFM refrigeration system. The actual BTU/h is now reduced to 155,762 BTU/h to reactivate the desiccant. The motors are now smaller and the ductwork is also smaller.

Energy Comparison

The energy comparison shows the desiccant system is the most costeffective way to control moisture loads in ice arenas. Actual moisture loads will vary from rink to rink, and ventilation standards to conform to outdoor air ventilation rates must be accommodated in the moisture-load calculations. This example does not include any outside air capacity; those loads must be added to conform to the International Mechanical Code.

A properly sized desiccant system is the most cost-effective way to condition an ice arena's ability to eliminate fog and condensation. Depending on fuel pricing and availability, it can also provide significant energy savings for the rink operator.

Comparison Points:

  1. When an equivalent sized desiccant unit is compared to the refrigeration coil, the cost of operation is lower for the desiccant system.
  2. Desiccant equipment is smaller and easier to maintain.
  3. There is no defrost cycle with the desiccant unit
  4. The airflow through the desiccant is constant, not reduced from ice formation
  5. The desiccant dehumidifier is independent of the ice refrigeration plant
  6. The cost to maintain the desiccant dehumidifier is lower than the associated cost to maintain the added capacity and run time on the refrigeration plant.

Todd Bradley
Certified Energy Manager
Application Specialist
Controlled Dehumidification IMS

  Refrigeration Capacity