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Puerto Rican-Based

Pharmaceutical Facilities

Puerto Rican-Based Pharmaceutical FacilitiesSee Dramatic Energy Cost Savings withPassive Dehumidifier Heat Pipes

Pharmaceutical 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.

How serious is the challenge of high humidity?

Plainly stated, tropical pharmaceutical production facilities need active humidity control or they risk a long list of potentially troublesome or hazardous events and conditions, including the growth of harmful bacteria, microbial contamination, non-sterile working condition, increased downtime (due to cleaning), and increased waste.

If that list looks long, there is more to add. High humidity can also negatively affect product packaging, the condition of coated pills, clogged powder feeders (due to moisture-laden powders), clogged tablet presses, and even the drying time in fluid bed driers.

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 / reheatprocess is generally disallowed by ASHRAE Standard 90.1-2010, Paragraph However, provision (d) of that Standard does allow overcool / reheat systems for process applications. That being said, even though it is allowable, brute force is grossly inefficient because it requires huge energy outlays and high costs.

To get an idea of the savings for using systems other than brute force, note this data from a brute force, 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 for an 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.) Let's compare these costs to an alternative approach.

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 elegant. They are designed tolower humidity levels, while avoiding the need to overcool and reheat air for use. Passive dehumidifier heat pipe systems are practically maintenance-free and have no moving parts, hence the passive designation in their name. They are so effective because they work on a simple theory of energy redistribution, not energy-intensive over-cooling. A wrap-around passive dehumidifier heat pipe system occupies a place on both sides of an HVAC cooling coil: the warm side, for pre-cooling incoming air, and the cool side, where air often has to be reheated before use in living/working areas, even in summer, because of the required over-cooling during dehumidification process. By distributing the heat around the HVAC cooling coil after extracting it from the incoming air, passive dehumidifier heat pipe systems allow facilities to avoid the energy cost required to reheat air.

The technology behind the heat pipe design was originally researched and developed by NASA, and Heat Pipe Technology (HPT) is one of the only companies globally to develop passive dehumidifier systems on an industrial scale.

One Obvious Solution

In our test case above, we know that the brute force solution has an annual energy cost of $53,900. But for the same location, the passive dehumidifier heat pipe system had a cost of only $34,400, for a 36% annual savings. Moreover, the savings from a passive dehumidifier heat pipe system will be ongoing, captured every year, and, moreover, heat pipes also have these additional benefits:
◦ Heat pipes have no moving parts, so no additional maintenance is required beyond normal coil cleaning.
◦ Heat pipes have exactly the same materials and methods of construction as the cooling coils for time-proven duty.
◦ Heat pipes allow either (a) downsizing of the cooling and heating central plants when heat pipes are installed in new AHUs, or (b) postponing capital expenditures of growing plants when heat pipes are installed in existing AHUs.
◦ Heat pipes can be used on both chilled water and direct expansion systems.
◦ Heat pipes use the same control sequence as the brute force method, but with today's Building Management Systems, it's easy to add some sensors and simple formulas that show and document real-time and "trending" energy savings.

AHU As a further note on costs, most AHUs can be site-fitted with wrap-around heat pipes as the most-cost-effective solution to a high humidity situation. If reheat coils are not used to control humidity, the life cycle costs are (a) the initial implementation cost and (b) the operating costs, which include maintenance and utilities cost.

With contemporary pricing, the incremental first cost of furnishing and installing wrap around heat pipes into a new 10,000 CFM AHU is about $13,000 total for a factory install, or about $21,000 for a site retrofit. The annual reduced utilities cost has already been determined to be $19,500.

So, the paybacks are 9 and 13 months for heat pipes installed in new or existing equipment respectively. (Since there are no moving parts associated with the heat pipes, and the materials of construction are the same as the other coil surfaces in the AHU, maintenance would only cost around $120 per year.)

Heat Pipe Technology - Two Comparison Cost Studies

HPT 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. For the 100% outside air system, the payback was 11.5 months after installation costs of $88,000, and net savings of $91,000 annually, which will continue for years to come. In the second case, with mixed air, the payback was just 10.3 months, after an installation that cost $50,000 and yielded $58,000 in annual savings, savings that will continue to compound in future years.

In both cases, there is clear and ample evidence that the green approach of passive dehumidifier heat pipes can have short paybacks and dramatic savings, year after year.

Case 1
HPT System: Site Retrofit
Pharmaceutical Manufacturer: 100% Outside Air
Location: San Juan, Puerto Rico


Summary Results

Case 2
HPT System: Site Retrofit
Pharmaceutical Manufacturer: Mixed Air
Location: San Juan, Puerto Rico

Summary Results:

[1]If rates are higher in your area, the return on investment will be higher and the payback more rapid.