Cost Savings with Passive Dehumidifier Heat Pipes

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Puerto Rican-Based Pharmaceutical Facilities See Dramatic Energy Cost Savings with Passive Dehumidifier Heat Pipes

HPT - Puerto RicoPharmaceutical production is popular in many tropical locations because of regulatory, tax, and labor-cost benefits. Yet many of the benefits can be easily negated if a production facility doesn’t properly mitigate high humidity, an environmental feature that comes part and parcel with any tropical location.

Two Approaches to Controlling Humidity

  • Brute Force. The first approach to controlling humidity, uses so-called brute force – which means overcooling the air to reduce the humidity, and then (as counterproductive as it seems in tropical environments) reheating the air to achieve design temperatures.  Brute force is very costly and the overcool / reheat process is generally disallowed by ASHRAE Standard 90.1-2010
  • Green Approach. The second approach to humidity control – often called a green approach for the energy it saves – involves using a passive dehumidification system.  Passive dehumidification systems, such as dehumidifier heat pipes, are remarkably simple and easy to apply.   See related Blog post:   Wrap Around Heat Pipe | How Does A Wrap Around Heat Pipe Work?

Lets Look at the Numbers

HPT - Puerto Rico - AHUSystem:  10,000 CFM mixed-air system in San Juan, Puerto Rico. The system supplies constant 62°F dry bulb and 53°F dew point air

Brute Force Cost:  Annual cost of $53,900. (That figure is calculated in this way: Assuming 24/7, 50% OA, 75°F DB/50% RH Return Air, at .70 Kw/ton cooling and 70% heating system efficiencies, and $.15/Kwh, $1.50/therm.)

Green Approach:  For the same location, the passive dehumidifier heat pipe system had a cost of only $34,400, for a 36% annual savings.

Heat Pipe Technology – Two Comparison Cost Studies

Heat Pipe Technology has recently completed two retrofits in Puerto Rico using passive dehumidification heat pipe systems. One was for a pharmaceutical facility using 100% outside air, and one for a pharmaceutical facility using mixed air. In both cases, the green approach of passive dehumidifier heat pipes dramatically reduced energy costs over the brute force approach used in the facilities.  

Case 1:

Heat Pipe Technology System: Site Retrofit
HPT - Puerto Rico - HPTApplication: 100% Outside Air
Location: San Juan, Puerto Rico

• 50,000 CFM Total Air:
• 525 fpm Air Velocity
• Hot Water Reheat 10°F
• Energy Cost:
     o Natural Gas $1.78 per therm
     o Electric Rate $0.19/kwh
• 24/7 operation; 365 days/year

Summary Results
• Precool Savings: $28,000
• Reheat Savings: $70,000
• Fan Penalty: $7,500
• Net Savings: $91,000
• Installation Cost Estimate: $88,000
• Simple Payback: 11.5 months

Case 2:

Heat Pipe Technology System: Site Retrofit
Wrap Around Heat PipeApplication: Mixed Air
Location: San Juan, Puerto Rico

• 22,800 CFM of Total Air (1,800 CFM O/A, 21,000 CFM Re-circulated)
• 456 fpm Air Velocity
• Hot Water Reheat 8°F
• Energy Cost:
     o Natural Gas $2.0 per therm
     o Electric Rate $0.16/kwh
• 24/7 operation; 365 days/year
• Standard plant efficiencies

Summary Results:
• Precool Savings: $18,000
• Reheat Savings: $45,000
• Fan Penalty: $4,000
• Net Savings: $58,000
• Installation Cost Estimate: $50,000
• Simple Payback: 10.3 months

Related Blog Posts:   
5 Benefits Of Using Wrap Around Heat Pipes
Ask Rick: Wrap Around Heat Pipes | What Is A Typical Payback?

For More Information - askRick

 

 

 

 

 

 

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